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BulletinTHE ROYAL SOCIETY OF CHEMISTRY

ENVIRONMENTAL CHEMISTRY GROUP

1

July 2005

Microbial immobilisationof Tc-99 ................................................................... 2

Meeting report: AirPollution 2005 ................................................... 4

Global warming and CO2 ...................... 5

BGS urban soil survey .............................. 8

Effect of compost on soilmetal content ................................................... 10

World Wetland DayConference 2005 .......................................... 12

2005 ECG DGL ............................................ 13

Meeting report: FaradayDiscussion 130 .............................................. 14

RSC AD Hilger Prize ............................. 15

Forthcoming meeting:2006 ECG DGL ............................................ 15

Meeting report: Outdoor andindoor air pollution research ........... 16

Comment: Fish stocks andendocrine disruptors ................................. 17

Meeting report: Pharmaceuticalsin the environment ..................................... 18

Recent acquisitions by theRSC library ...................................................... 20

Issues of the ECG Bulletin may beseen at:http://www.rsc.org/Membership/Networking/InterestGroups/Environmental/bulletin.asp

BULLETIN EDITORDr Rupert Purchase,38 Sergison Close,Haywards Heath,West Sussex RH16 1HU

ChairmanDr Brendan Keely,Department of Chemistry,University of York,Heslington,York YO10 5DDTel: 01904 [email protected]

Vice-Chairman &Honorary TreasurerDr Andrea Jackson,School of the Environment,University of Leeds,Leeds LS2 9JTTel: 0113 233 [email protected]

Honorary SecretaryJo Barnes,The Air Quality Unit,Cornwall College Camborne,Opie Building,Trevenson Road,Pool, Redruth,Cornwall TR15 3RDTel: 01209 [email protected]

CONTENTS

ECG Bulletin – July 2005

RSC ENVIRONMENTAL CHEMISTRY GROUP OFFICERS(from March 2005)

A massive tabular iceberg adrift in the Weddell Sea off the Antarctic Peninsula.(Photo: British Antarctic Survey/C. Gilbert, PA). The disintegration of the 200-metre thick, 3,250 square kilometre Larsen B ice shelf into the Weddell sea in2002 has been attributed to global warming. An understanding of the infra-red spectroscopy of carbon dioxide and water illuminates their relative rolesas a greenhouse gases and in the causes of global warming (p. 5).

Environmental Chemistry Group Bulletin July 2005

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How microbial processes in estuarine sediments can control themobility of technetium-99

Results from anoxic micro-cosm experimentsIn anoxic microcosms experiments, over99% of Tc was removed from porewaters within approximately 20 days(Fig. 3). In sterile controls, however, Tcremained in solution as TcO4

- indicatingthat Tc removal to sediments is abiologically mediated process. A classiccascade of terminal electron acceptingprocesses (TEAPs) was observed and Tcremoval occurred at the same time asactive ingrowth of sediment boundFe(II). At the concentrations used inthese experiments, microbes areprobably not able to directly utilise Tcas a TEAP (4), and Tc removal mostlikely occurs indirectly as a result ofreaction with reduced species in

Ian Burke, Robert Mortimerand Katherine Morris at theSchool of Earth andEnvironment, University ofLeeds, together with ChrisBoothman, Francis Livensand Jon Lloyd, at the Schoolof Earth and Atmospheric andEnvironmental Sciences,University of Manchester,discuss how indigenousmicrobial processes insediments can lead totechnetium-99, a radionuclidepresent in radioactive wastes,being removed from solutionand retained in sediments ashydrous TcO2.

Introduction

Technetium-99 is a long lived (half-life,2.13 x 105 years), β-emitting radionuclidethat is significant in radioactive wastes.Under oxic conditions technetium ispresent as the pertechnetate ion (TcO4

-),which is weakly sorbed to mineralsurfaces and is one of the most mobileradionuclide species in the environment(1). By contrast, in reducingenvironments the lower valence forms oftechnetium (predominantly Tc4+) formsolid phases, and strong surfacecomplexes with Al and Fe oxides andclays (2). Because of the long half-lifeof Tc, and its high environmentalmobility, understanding the controls onhow Tc is reduced and scavenged bysediments is essential to informing policyon how best to manage this contaminant.Within the natural environment, Tc ispresent at ultra-trace concentrations.This, combined with difficulties in itsanalysis, means that there is a paucity ofenvironmental data for the radionuclideand little is understood of the solid phaseinteractions of technetium in theenvironment (3).

We used sediment microcosmexperiments (Fig. 1) containing

Fig. 1: Anaerobic microcosm experimentscontaining Humber Estuary sediments with;(from left to right) three Tc-amendedexperiments, an unsealed control, a non Tc-amended control and a sterilised Tc-amendedcontrol. All have been incubated at 10˚C for40 days in the dark.

sediments uncontaminated with Tc fromthree different Humber Estuary sites.Sampling occurred with minimaldisturbance so that the full indigenousmicrobial populations within thesediment remained in experiments (e.g.Fig 2). Microcosms were spiked with 1-5 µM TcO4

-, and the behaviour of Tc andother redox indicator species wereobserved as progressive anoxiadeveloped. By determining a range ofredox indicator species, characterisingthe resident microbial community, andinvestigating the fate of Tc in thesesediments, we were able to significantlyincrease understanding of thebiogeochemical processes that have thegreatest effect on Tc solubility in thenatural environment.

Fig. 2: Ian Burke shortly after sampling surfacesediment from Humber Estuary mudflats atBoothferry. Care was taken to sample only thetop few millimetres of the sediment surface.Face masks, gloves and sterile containerswere used to protect samples (butunfortunately not Ian) from potentialcontamination.

sediments. Although sulfate reductionwas observed in some experiments, itoccurred after Tc removal was >99%complete. This indicates that microbialsulfate reduction was not an importantfactor in controlling Tc removal in thesesediments (e.g. through the productionof sulfide which can reduce andprecipitate Tc). As Tc-solubility is notaffected in experiments where nitrate ormanganese reduction is the sole terminalelectron accepting process (5,6), abioticreduction of Tc(VII) onto solid Fe(II)containing-phases, formed as a result ofbacterially mediated Fe(III) reduction, istherefore the most likely controllingmechanism for Tc-solubility in theseexperiments. This was confirmed inexperiments where sterilised Humber


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Estuary sediments were inoculated withpure microbial cultures capable of eithernitrate, iron or sulphate reduction. Inthese experiments Tc reduction onlyoccurred in those sediments where theactive accumulation of Fe(II) wasdetected in sediments as a result ofmicrobial Fe(III) reduction.

microbial incubations,species were presentthat were able toswitch to each TEAPin turn as it becamethe most energeticallyfavourable mode ofrespiration. In anattempt to isolate themicrobes capable ofFe(III) reduction,potentially the most important inmediating Tc reduction, 10% sedimentinoculums were incubated in Fe(III)containing media and repeatedly sub-cultured. 16S rDNA analysis of thisextracted culture produced a clone librarydominated by Shewanella sp. Thisspecies when reintroduced to sterilisedsediments was found to be able tomediated Fe(III) and Tc reduction inthose sediments.

Fate of Tc in sedimentsThe Tc-phase that sorbed to sedimentswas investigated using extended X-rayabsorption spectroscopy fine edgestructure analysis (EXAFS) at theDaresbury synchrotron light source. Thedetection limit constraints of EXAFSrequired a much higher Tc concentrationthan our previous experiments.Sediments undergoing Fe(III)- andsulfate-reduction, respectively, wereamended with 1000 µM TcO4

-. Understrictly anaerobic conditions, Tc removaloccurred within 2 days due to abioticreaction with reduced phases in thosesediments. In addition, oxic sedimentswere also incubated anaerobically with1000 µM TcO4

-. Here, microbiallymediated ingrowth of extractable Fe(II)was observed over a 6 month incubationperiod, and >99% Tc was removed fromsolution, representing one of the highestTc concentrations known to have beenreduced by naturally occurring microbialprocesses. The main features in theEXAFS spectra and Fourier transformsfor all three samples are very similar (Fig.4), and modeling produced good fits forall of the samples with an inner shell ofsix oxygen backscatterers at ca. 2.00 Å.This is consistent with the formation ofhydrous Tc(IV)O2-like phases (8),previously reported as microbialreduction products by other workers(6,9), and confirms that the removal ofTcO4

- from solution was accompanied bythe formation of hydrous TcO2.

Implications for Tc behaviorin the natural environmentIn our anoxic incubation experiments,indigenous Fe(III)-reducing bacteriawere stimulated when the reduction ofmetals represented the most energeticallyfavorable TEAP, and Tc reduction wasassociated with the active accumulationof microbially generated Fe(II) insediments. EXAFS demonstrated that Tcformed a hydrous TcO2 phase withinthese sediments under both Fe(III)- andsulfate-reducing conditions. This impliesthat TcO4

- released to the environmentwill be scavenged to sediments byreductive precipitation to hydrous TcO2when active Fe(III) reduction isoccurring or when it is exposed toFe(III)- or sulfate-reducing sediments.Therefore, when TcO4

- is discharged intooxic environments, Tc reduction isapparently mediated by a potentiallywide variety of microbes, and reducingsediments may preferentially accumulateTc(IV) rather than diluting anddispersing it as TcO4

-. This may be usedto advantage in understanding thebiogeochemistry of technetium inestuarine environments as well as inremediation of Tc contamination in arange of environments.

AcknowledgementsThis work was funded by NERC grants,NER/A/S/2001/00652 and NER/A/S/2001/00960, and a CCLRC beamtimeaward at Daresbury SRS.

Fig. 3: Time series of Tc-removal during anincubation of Humber Estuary sediments (•)amended with 5 µM Tc. Tc-removal does notoccur in sterile controls (+) indicating abiologically controlled process

Microbial communityanalysisA combination of culture and DNAdependent techniques was used todetermine the microbial communitypresent during Tc removal and to assesshow that community changed with timeduring anoxic incubation. Intergenicspacer analysis has been successfullyused in other sediments (7) to‘fingerprint’ changes in microbialcommunities, but in Humber Estuarysediments this technique showed that themicrobial communities present at all siteswere complex and closely related. Inaddition even though nitrate-,manganese-, iron- and sulfate-reductionwere observed in a classic redox cascadeorder, no changes in community structureoccurred over the same timescales.Analysis of a 500 b. p. region of extractedmicrobial 16S rDNA amplified usingbroad specificity PCR primers, typed byRFLP and sequenced, revealed a verycomplex clone library dominated by g-Proteobacteria. Bacteria related toorganisms capable of a wide diversity ofaerobic and anaerobic processesincluding known nitrate-reducing(Rhodobacter sp.), metal/sulfur-(Pelobacter sp.) and sulfate-reducingbacteria (Desulfovibrio sp.) were present.Therefore, even though the microbialpopulation remained constant during

Fig. 4: (a) k3-weighted Tc K-edge EXAFSspectra and (b) Fourier transforms of the Tc-labeled sediments used in the microcosmexperiments of the following (bottom to top):solid pertechnetate standard (8); sulfate-reducing sediment amended with 1000 µM Tc;Fe(III)-reducing sediment amended with 1000µM Tc; progressive anoxia, biotic sedimentamended with 1000 µM Tc. The black linesrepresent experimental data and the gray linesrepresent the best model fit using EXCURV98.All three reduced samples were most closelymodeled by hydrous Tc(IV)O2-like phases.

(a) (b)


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References(1) Morris, K.; Butterworth, J. C.;

Livens, F. R., Est. Coast. ShelfSci., 2000, 51, 613-625.

(2) Keith-Roach, M.; Morris, K.;Dahlgaard, H., Mar. Chem.,2003, 81, 149-162.

(3) Standring, W. J. F.; Oughton,D. H.; Salbu, B., Environ. Sci.Technol., 2002, 36, 2330-2337.

(4) Lloyd, J. R.; Ridley, J.;Khizniak, T.; Lyalikova, N.N.; Macaskie, L. E., Appl.Environ. Microbiol., 1999, 65,2691-2696.

(5) Abdelouas, A.; Fattahi, M.;Grambow, B.; Vichot, L.;

Gautier, E., Radiochim. Acta,2002, 90, 773-777.

(6) Fredrickson, J. K.; Zachara, J.M.; Kennedy, D. W.;Kukkadapu, R. K.; McKinley,J. P.; Heald, S. M.; Liu, C. X.;Plymale, A. E., Geochim.,Cosmochim. Acta, 2004, 68,3171-3187.

(7) Islam, F. S.; Gault, A. G.;Boothman, C.; Polya, D. A.;Charnock, J. M.; Chatterjee,D.; Lloyd, J. R., Nature, 2004,430, 68-71.

(8) Wharton, M. J.; Atkins, B.;Charnock, J. M.; Livens, F.R.; Pattrick, R. A. D.;Collison, D., Appl. Geochem.,

2000, 15, 347-354.(9) Lloyd, J. R.; Solé, V. A.; Van

Praagh, C. V. G.; Lovley, D.R., Appl. Environ. Microbiol.,2000, 66, 3743-3749.

A full report of this work − Effects ofprogressive anoxia on the solubility oftechnetium in sediments − appears inEnvironmental Science and Technology,2005, 39, 4109-4116.

IAN BURKE([email protected]),School of Earth and Environment,University of Leeds,May 2005

Meeting reportAir Quality Management sessionsexamined the provision of air quality datafor local government and the public (e.g.Barnes and co-workers: “GIS mappingof NO2 diffusion tube monitoring inCornwall, UK”). Other topics included:urban air pollution, modelling andmonitoring; cross channel pollution; andbiogenic volatile organic compounds.

Other noteworthy contributions at theconference included:

• Elmi and co-workers (Bologna): “Alow-cost transportable instrumentbased on microsystem technologiesfor benzene monitoring in outdoorair”. The instrument is planned forproduction in 2006 at a cost ofaround £7K. The apparatus has adetection limit of 0.2 ppb withhourly reporting, self-calibrationand an in-field unattended lifetimeof 6 months. It would be a welcomesimplification of the cumbersomeand complex array currently used forbenzene monitoring.

• Al-Rashidi (Loughborough): “Airquality modelling of sulphur dioxideemission from power plants inKuwait”. The conclusion of thispaper was a clear recommendationfor the optimum sulphur content ofthe fuel used in the power plants. Butit was the successful use of the US-EPA approved ISCST3 model(industrial source complex modelfor short-term prediction) to

quantify the impact of SO2 releasewhich was of interest. The relativelyuncomplicated terrain andmeteorology together with well-defined emission sources made thisa good case study for the applicationof the ISCST3 AQM.

• Stewart and Andino (Florida):“Studies of the uptake of gaseousethyl 3-ethoxypropionate ontoammonium sulfate and ammoniumnitrate aerosol particles”. Work onthe uptake, loss, and transport, oforganic species by atmosphericaerosols that highlighted theimportance of such heterogeneousinteractions in the troposphere.

• Kretzschmar (Flemish Institute forTechnological Research):“Greenhouse gas emissions in theEU: are we reaching the Kyotoobjectives?” An update of Kyotoprotocol compliance by the 15 EUmember states, which suggested thatthe set targets may be difficult –though not impossible – to achieveby the 2008-2012 deadline.

JO BARNES,Air Quality Unit, Cornwall College

* Brebbia, C. A. (Ed.), Air Pollution XIII,WIT Press, Southampton, 2005.ISBN 1-84564-014-4. Volume 82, WITTransactions on Ecology and theEnvironment. http://library.witpress.com/pages/listBooks.asp?tID=4

Air Pollution 2005:Modelling, Monitoring andManagement of Air Pollution

XIII International Conference on AirPollution, Cordoba, Spain, May 2005

Based in the New Forest, the WessexInstitute of Technology (WIT) is acommercial enterprise focusing onpublishing, conference organisation andsoftware services for academia andindustry. On May 16-18 2005, WITorganised the 13th International AirPollution Conference at the HotelHesperia Cordoba, Spain. Presentationsat this conference described themodelling, monitoring and managementof air pollution, and the proceedings havenow been published.*

The presence of 100+ delegates from 30countries (ranging from the US, Chile,Brazil, and Canada to Europe, Korea,Japan, and Kuwait) reflected the interestof planners and legislators in air qualitydata and related legislation.

The opening paper “Micromixing effectsin air pollution modelling” (Richardson,Cambridge) described methods by whichair quality models (AQMs) can beimproved to predict more accurately anysignificant variations in theconcentrations of pollutant species thatmay occur over small distances. Relatedpapers discussed modelling air qualityemissions in cities (Santiago) and fromindustry (refineries and power plants).


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Global warming: the physical chemistryAbout 30% of this radiation is reflected,mainly by clouds, and the rest warmsEarth so that it too radiates,approximately as a black body. Theincoming and outgoing energy reach anequilibrium position, determined by ourdistance from the sun. (Partial black bodycurves for various temperatures areshown in Figures 1 and 2). (Note 1).

In the absence of any absorption of theoutgoing energy, the average equilibriumtemperature of our planet would be255K. Thus nearly all the surface of theplanet would be expected to be wellbelow the melting point of ice, so that itis at least questionable whether or notlife, dependent on liquid water, couldhave followed the path we know (Note2), without the additional warming whichgives us the current average temperatureof about 288 K.

Much of this additional warming comesfrom absorption of the outgoing radiationby atmospheric water vapour. Althoughwater has strong IR absorption in the“group vibration” region, the mostsignificant energy absorption is from thevery strong and complex rotationalstructure between ca. 1 cm-1 and ca. 700cm-1. The upper part of this regionoverlaps with the lower frequency regionof the outgoing 288K black bodyspectrum, so that much of this energy isabsorbed in the atmosphere, and then re-radiated (Note 3). Because some of thisre-radiated energy is returned to earth,the net radiation reaching the surface isgreater than it would be with noatmospheric absorption, and the surfacetemperature rises. However, obtainingquantitative estimates of the warmingdue to this is far from trivial. The firstpoint to make is that there is a positivefeedback effect – as the temperaturerises, so does the saturation vapourpressure of water, so more water entersthe atmosphere, and this produces morewarming. However, not all theatmosphere is saturated (Note 4) withrespect to water, so quantifying this iscomplex; solar reflection by clouds, thevariation of cloud cover with watercontent, and atmospheric convection,also have to be included. Currentestimates give a warming contributiondue to water alone of about 20K, andabout half of this comes from the“feedback” effect (Note 5).

This only accounts for two-thirds of thetotal warming (about 30K). Therotational absorption intensity of waterfalls off rapidly above about 500 cm-1,as the population of rotational levelsdecreases following the Boltzmanndistribution. Thus the higher frequenciesof the black body emission aretransmitted – there is a “water window”in the atmospheric absorption whichreaches up to about 1200 cm-1, where thefirst of the water vibration-rotationbands, associated with the bendingvibration, begins. The lowest (bending)vibrational band of carbon dioxide fitsinto the lower frequency region of thiswindow, and this accounts for most ofthe rest of the warming. Thus the“natural” or “primary” greenhouse effectis a sum of the effects of water and thenatural background of about 280 ppm ofCO2, with some smaller contributionsfrom other sources (including ozone,which absorbs close to the centre of thewindow). For many centuries the levelof CO2 was constant, as can be seen inice-core measurements, but since about1800 it has been increasing, and the rateof increase has also increased, giving acurrent (2003) level of about 375 ppm.It is the additional warming above thenatural level, due to emissions fromhuman activities, which is commonlyreferred to as the “greenhouse effect”.

Figures 1 and 2 illustrate some of thesepoints (Note 6). Figure 1 is the IRemission from Earth, measured above theatmosphere at a particularly dry position– the Sahara. The Earth black body curvecan be seen in the atmospheric (“ATM”)window at position C; this is beingemitted from ground level. Most of therest of the rest of the spectrum is thatemitted by molecules within theatmosphere. Even in this “dry” spectrumthere is a lot of water emission below 700cm-1 and above 1300 cm-1, but since theemission is not saturated, individualcomponents (Note 7) show as sharppeaks. This radiation comes from severalkm high in the atmosphere (see the right-hand graph in Fig. 1), where thetemperature is much lower. The mostprominent feature in the spectrum is thevery strong CO2 feature from about 550cm-1 to 800 cm-1. The broad “flat-topped”nature of the centre portion of this

Despite the widespreadscientific consensus, and thepartial political agreement thatglobal warming is a seriousproblem which is largely man-made, there are doubters. Theserange from newspapercolumnists who make a virtueof scientific ignorance, webpundits and even novelists, to(a few) serious climatologistswho dispute subtle aspects ofthe modelling. In between,there seem to be some puzzledchemists, and even a fewsceptical ones. ProfessorRobert Lloyd, formerly ofTrinity College, Dublin,describes how the infra-redabsorption spectra of carbondioxide and water explain theirrelative importance as green-house gases and as contributorsto global warming.

This article is an attempt to clear up somecommon misconceptions which arise atthe relatively low level of the basicphysical chemistry/physics of the infra-red (IR). In this area, we chemists maybe at something of a disadvantagebecause of our training. We are veryfamiliar with a part of the total IRspectrum, but the “group vibration”region, about 4000 - 1000 cm-1 (2.5 - 10 µ),is not the region of greatest importanceto global warming effects. Furthermore,we have all been taught not to put toomuch material into our mulls orsolutions; if we do, the beautiful sharppeaks turn into ugly flat-topped objects,since saturation is occurring. Suchsaturation is very important inunderstanding what is going on in globalwarming.

Much of the radiant energy from the sun,which approximates to a black body at5780K, is transmitted well by theatmosphere, which is almost transparentin the visible and near-visible regions.


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spectrum contrasts with the sharp peak,due to the Q branch, which is shown inmost textbook (absorption) spectra. Thisis the result of saturation: not only is theQ branch saturated, but so are most ofthe wings of the adjacent P and Rbranches, and everything in between; inthis saturated region the emissionmatches the high-altitude black bodycurve at about 218K. This energy,originally emitted at the surface, has beenabsorbed and re-emitted several timesthrough successively cooler regions. The“missing energy” between the 218K and320K curves has been returned to thesurface. The spectrum also shows the re-emission of radiation absorbed by ozonein the upper atmosphere, about 2-3 kmaltitude, and by methane (see below).

Figure 2 shows the converse situation –a ground-based spectrometer is “lookingupwards” at the downward emittedradiation, but now with more normalhumidity, so most of the water emissionat wavenumbers below 550 cm-1 is atsaturation, and this comes from a lowaltitude, temperature about 275K. Againthe very intense emission between 650cm-1 and 750 cm-1 is due to atmosphericCO2. CO2 emission is therefore returningmuch of the radiation emitted from Earthover a fairly wide slice, close to themaximum of the spectrum of black bodyradiation (Note 8).

The effects of increasing the CO2 levelare not simple. It might be thought thatonce there is enough of any “greenhousegas” in the atmosphere for saturation to

have been reached, absorption ofradiation is complete, so there could beno more warming, but this is not so.Firstly, the saturation only applies to thecentre region. At the wings, increasingconcentration increases the number ofphotons absorbed, and returned to earth.Furthermore, there is still a warmingeffect at the surface due to the centre ofthe band, because the first absorptionnow takes place at a lower altitude, wherethe temperature is higher. This energy isre-emitted, and more energy is returnedto the surface. However, this is a verynon-linear effect – the warming is notdirectly proportional to the number ofmolecules added, but rises more slowly.It needs to be emphasised, in view ofcertain media comments, that thewarming effect from CO2, both naturaland anthropogenic, is amplified by thewater feedback mechanism, as the effectof water itself is (see above). Far from“ignoring water as a greenhouse gas” assome pundits proclaim, workers inclimate modelling build this effect in toall their models. This amplification of theCO2 warming effect by water isresponsible for the predicted substantialwarming over the next century or so, withall the very serious consequences.

Other “greenhouse gases”, thoughpresent in much smaller amounts, makeappreciable contributions because theyabsorb in the remaining window regionwhere neither CO2 nor H2O absorb verystrongly. Methane is significant now, butmay have been catastrophic in the past.A major change in the ancient history of

the Earth has been associated withwarming following the decomposition ofthe methane-water clathrate (Note 9), andlarge amounts of this are known to bepresent now. The methane absorptionband can be seen in Figure 1, though inFigure 2 it has been lost in theoverlapping of the traces of many waterlines. This absorption is currently wellshort of saturation, so warming effectsare approximately linear in the numberof molecules added, and per molecule,methane is about 50 times more effectivethan CO2, at least in the short term (upperatmosphere chemistry slowly destroysmethane). As a result, methane fromagriculture can be a large componentof total greenhouse emissions forcountries, even in the developed world,for example Ireland and New Zealand.Nitrous oxide and halocarbons alsocontribute to the total. As a result, despitethe small concentrations of theseminority species, their heating effectstaken together are more than one-thirdof the total effect from man-madegreenhouse gases (Note 10).

Clearly the “greenhouse effect” is a veryintricate subject, and this short note hasonly attempted to deal with the verybeginning of the complex process whichgenerates climate. I hope it has been ofsome help, and the further reading listedbelow should allow access to the vastamount of real data and explanationwhich is available.

Figure 1: Infra-red emission spectrum from Earth, taken at high altitudeover the Sahara (Copyright American Geophysical Union). The letters onthe spectrum indicate the approximate altitudes and temperatures forparticular emission features: see the curve in the right-hand section. Thedashed lines show the energy distributions for a black body at varioustemperatures.

Figure 2: As Figure 1, but now on a ground-basedspectrometer recording emission to Earth from the verticalcolumn of the atmosphere, with a higher water content thanin Figure 1. (Modified from a version provided on the ESPEREwebsite).

Wavenumber cm-1

CO2

200K

280K


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4.2.1.1.10 See IPCC: Climate Change 2001:

Working Group I: The ScientificBasis 6.3.4

Further information

This article has to some extent followedthe approach in A. P. Cox, “TheElements on Earth” (Oxford 1995), pp14-19, with some amplification. IRspectra of the various moleculesmentioned are available (at mediumresolution) at http://webbook.nist.gov/chemistry/

Various other websites give some detailson the stages by which the spectroscopicinformation is turned into models of theclimate of the earth; one of the mostdetailed, which nevertheless is well-organised into links, so that particularinterests can be followed through, is athttp://www.aip.org/history/climate/index.html

As an introduction to this, there is aspectacular demonstration of the way inwhich global temperature and CO2 levelshave tracked each other over 160,000years at http://www.aip.org/history/climate/xVostokCO2.htm

A site which attempts to answerindividual problems is www.realclimate.org/index.php?p=1

There is a large, somewhat indigestiblebut authoritative collection of documentsfrom the Intergovernmental Panel onClimate Change (IPCC) at http://www.gr ida .no/c l imate / ipcc_tar /index.htm

Within this the most directly relevantmaterial to this note is the discussion ofcarbon species athttp://www.grida.no/climate/ipcc_tar/wg1/095.htm and of the effects of theabsorbed radiation athttp://www.grida.no/climate/ipcc_tar/wg1/212.htm

Acknowledgements

I am particularly grateful to ProfessorNorman Sheppard, who provided adviceat an earlier stage of this manuscript, andto Dr. Rob Jones of the ChemistryDepartment, University of Cambridge,

Notes

1 These are plotted as energy densityper wavenumber on a horizontalscale linear in wavenumbers. Manyphysics texts show curves linear inwavelength, and on these themaxima occur at different positions.

2 It is also of great importance to lifethat one part of the solar emissionis absorbed significantly by theatmosphere, the hard UV radiation,which is removed by ozone.

3 In addition, there is a componentfrom the “water bend” vibration, butthere is not much of the total energyof the black body emission at thesehigher frequencies.

4 Unfortunately, the word“saturation” is used both for theSVP and for infrared absorption,though there is no necessaryconnection between these uses. Inthe rest of this note, the word refersto saturation of IR absorption.

5 See IPCC, referenced in “Furtherinformation”, Technical summary,D.1 Climate Processes andFeedbacks.

6 A more dramatic version of Figure2, in which the “window” isemphasised by colouring varioussections, can be found at:www.espere.net/Unitedkingdom/water/uk_watervapour.html#x3.Similar spectra, obtained underdifferent conditions can be found at:http://cimss.ssec.wisc.edu/aeri/science/aeriret/

7 The rotational structure is verycomplex, and many of the apparentpeaks in the figures consist ofseveral components.

8 Since the intensities at saturation arecontrolled by temperature, theemission envelope follows a blackbody curve, and information aboutatmospheric temperature profilescan be extracted from such spectra;see the links in note 6.

9 “However, these deposits areenormous, about 107 TgC, and thereis an indication of a catastrophicrelease of a gaseous carboncompound about 55 million yearsago, which has been attributed to alarge-scale perturbation of CH4hydrate deposits”; see IPCCClimate Change 2001: WorkingGroup I: The Scientific Basis

for a detailed discussion, and for makingFigure 1 available. Any remaining errorsare my responsibility. I would also liketo note the contributions of two SkepticalChymists, who in extensivecorrespondence have forced me to clarifymy own ideas on this topic.

Biographical note

In 2000, BOB LLOYD retired from theChair of General Chemistry at TrinityCollege, Dublin, where he had helped toset up a new course in EnvironmentalChemistry. His research, (after a start insolution kinetics) has been mainly inphotoelectron spectroscopy and alliedmethods, initially in the gas phase (at theUniversity of Birmingham, to 1978) andlater in angle-resolved form on surfaces,particularly with adsorbed molecules.


8

Advances in surveying the soil chemistry of UK urban environmentsBarry Rawlins and KirstenO’Donnell from the BritishGeological Survey (Keyworth,Nottingham) describe theirwork on urban soil analysis.

Introduction

The soil acts as both a sink (repository)and source for contaminants in urbanenvironments. Diffuse pollution iswidely perceived to account for asignificant component of thecontamination of urban soils in the UK.But just how significant is diffusepollution? How can its magnitude beassessed in a complex and ever-changingenvironment? How can we account forthe presence of hotspots ofcontamination? Does the contaminationwe measure in the soil agree with ourexpectations given the distribution ofhistorical land use in the urban area?

The British Geological Survey, as partof its GSUE (Geochemical Surveys inUrban Environments) project has begunto answer some of these questions. Thisis part of fulfilling BGS’s role: theacquisition of geoscience knowledge andinformation (via surveying, monitoringand research), its interpretation,management and dissemination. Since1993, more than 7000 individual soilsamples have been collected from around20 urban centres (see Figure 1). Thesamples have been analysed for theirinorganic chemical composition,including a range of trace metals that arealso persistent contaminants. These dataare frequently provided to consultants,local authorities and researchers for avariety of applications. The excesssample from each sample is archived andlinked via a unique sample number to anelectronic database, which retains usefulinformation about the sample, includingits location and land use.

Point and diffuse pollution

We recently undertook a study on the soilchemistry data from Sheffield consistingof 569 sample locations. We usedadvanced spatial statistics to identifythose sites, which represent sites ofhotspots of contamination. They have

geologists as the Coal Measures. Wealso have soil chemistry data for soilsamples developed from the CoalMeasures in rural areas. We firstremoved the hotspots from the urbandataset and then compared the medianvalues (a robust measure of the centre ofa distribution) from the urban and ruralsoils for three elements: lead, chromiumand nickel. We believe that a substantialdifference between the median valuesprovides an estimate of historical diffusepollution. The difference for lead wassubstantial; the urban median (203 mgkg-1) was twice the rural median (101 mgkg-1). At this stage we cannot commenton the relative magnitude of the differentsources, but historical use of leadedpetrol may be one of a number ofsignificant contributors. The differencesfor chromium and nickel were moremodest – increases of 14 and 25%respectively. To our knowledge this isthe first attempt to estimate diffusepollution in urban soil in the UK. Thiswork is presented in more detail in aforthcoming paper in Soil Use andManagement (Rawlins et al., in press).

unusually high concentrations in relationto neighbouring sample locations. Figure2a shows a smoothed map of Crconcentrations across the City; the siteshotspots of contamination are shown asblack dots. The smoothed map in Figure2b was created with these hotspotsremoved and gives a more accuraterepresentation of the background processcombining the natural soil chemistry plusa component of diffuse pollution. Thehighest soil Cr concentrations in bothmaps occur to the north-east of the City.This accords with its widespread use insteel manufacturing which hashistorically been sited in this part of theCity. Statistical analysis showed therewas an association between historicalland-use, based on Ordnance surveymaps, and Cr hotspots.

One way to estimate the amount ofdiffuse pollution in urban soil is tocompare them to a series of soils in ruralareas that developed from the sameparent material. Sheffield is well suitedfor this as it positioned in the middle ofa widespread rock type referred to by

Figure 1: Urban centres surveyed by BGS between 1993 and 2005.


9

Comparison between urbancentres

The BGS has soil data covering ruralareas, as well as seven urban centresacross the Humber-Trent region. This isa unique soil geochemical datasetenabling comparison of closelydistributed UK urban centres with theregional baseline. One of the mainapplications is improving ourunderstanding of the nature of urban soilgeochemistry, which may vary betweenurban areas as a result of differences inindustrial history, transportation andunderlying parent material types.

Figures 3a and 3b illustrate features ofthe distributions of arsenic (As) and lead(Pb) respectively in the seven Humber-Trent urban areas and in the non-urban

land (labelled Humber-Trent). The lowerand upper ends of the boxes represent the25th and 75th percentiles, the line is themedian and the cross is the mean of thedata. The dotted line in Figure 3arepresents the soil guideline value (SGV)for As in soils of residential land use (20mg/kg). The SGV for Pb (450 mg/kg) isoutside of the range shown in the boxand whisker plot (Figure 3b). Elevatedlevels of As in the urban soils ofScunthorpe and Sheffield, with respectto the regional distribution and the SGVcan be attributed to the location of theseurban areas over the FrodinghamIronstone and the Carboniferous CoalMeasures, respectively, which are bothenriched in a number of trace elements,including As. The exploitation of coalaround Sheffield may also havecontributed to elevated concentrations oftrace elements in the urban soils.

Elevated levels of As and Pb occur in thesoils of Kingston-upon-Hull relative tothe regional baseline. The latter may inpart be related to the former operation ofa metal smelter to the west of the city.Although the levels of As in the otherurban areas approach the SGV, exceedingit in some cases in the upper ranges, theyare fairly consistent with the regionaldistribution. This suggests that As isnaturally elevated in the soils of theHumber-Trent region as a whole.Although the concentrations of Pb in theHumber-Trent urban soils arepredominantly below the SGV forresidential areas involving plant uptake,the skewed distributions, with strongdeviations of the mean values from themedians, are indicative of anthropogenic,point contamination.

Acknowledgement: We would like tothank Dr Murray Lark (RothamstedResearch) for his contribution to thegeostatistical analysis of the Sheffielddata.

Reference

Rawlins, B. G.; Lark, R. M.; O’Donnell,K. E.; Tye, A. M.; and Lister, T. R. inpress. The assessment of point and diffusesoil pollution from an urban geochemicalsurvey of Sheffield, England. Soil Useand Management, (2005).

British Geological Survey http://www.bgs.ac.uk/

Figure 2: Contour map of Cr concentrations in the soils ofSheffield: a) including contaminant hotspots (•), and b) withoutcontaminant hotspots (•) used for interpolation

Figure 3: Box and whisker plots of soil a)arsenic (As) and b) lead (Pb) concentrationsin the topsoil (0-15 cm depth) in variousurban centres and the rural soils of theregion (Humber-Trent)


10

Changes in soil metal content after addition of compostAten, 1993; Bucher and Schenk, 2000;Keller and Hammer, 2004).

The power of the extracting methoddepends on the soil characteristics.DTPA was first developed for calcareoussoils (Lindsay and Norvell, 1978) and issuitable for neutral to alkaline soils(Hammer and Keller, 2002). Zhang andShan (2000) found that DTPAextractants represented a highly availablemetal ion fraction of the total metalcontent. Brun et al. (2001) showed agood correlation between the DTPAextractable fraction and metalaccumulation in root maize grown on Cucontaminated soils. Pinamonti et al.(1999), in a study on the use of compost inviticulture, pointed out that theconcentration of heavy metals in planttissues was positively correlated with theDTPA-extractable form of the metals inthe soil, but was not correlated with thetotal or the EDTA-extractable forms. Otherauthors use a sequential extraction methodto analyse the different fractions in whichthe element is found (Tessier, 1979).

In this study, changes in metal contentresulting from the application ofcomposted cattle manure to a calcareoussoil were evaluated. Copper and zinc, themetals in higher proportion in the appliedresidues, were analysed.

Material and methods

Soil sampling

Samples were taken from a vineyard soil,which had undergone alterations to itssoil profile before vineyardestablishment some 12 years ago. Thecharacteristics of the soil are shown inTable 1. In order to improve soilproperties, composted cattle manure wasapplied at a rate of 40 Mg ha-1 inalternated rows, and mixed in the 25-cmupper layer. Soil sampling was carriedout one year after compost applicationin areas with and without compost andat 4 positions in the plot slope. Soilsamples were dried and sieved using a2-mm mesh.

Extraction procedures

Copper and zinc were analyzed in each soilsample. A simple extraction method was

performed in order to evaluate total metalcontent in the soils (digestion with an acidmixture: 2.5 mL 65% HNO3, 7.5 mL 37%HCl, and 2.5 mL deionised water).

The extractable metal fraction wasevaluated using DTPA (0.005 Mdiethylenetriaminepentaacetic acid, 0.1M triethanolamine, and 0.01 Mammonium acetate at pH 7.3). Thesequential extraction procedure proposedby Tessier (1979) was used to analysethe different forms: exchangeable, thecarbonate fraction, the fraction bound toFe and Mn oxides, the fraction bound toorganic matter and the residual fraction.Blank samples were prepared accordingto each procedure and the concentrationof the extracts was corrected bysubtracting the corresponding blankconcentration. All material was cleanedby soaking in 10% HNO3 (v/v) and thenrinsed with purified water. Metalconcentrations were measured by atomicabsorption spectroscopy. Two replicatesof each analysis were carried out, and theaverage value is reported.

Results

The analysed soils have relatively highsilt (40-45%) and sand contents (43-51%), but low clay contents (8-12%).Calcium carbonate content is relativelyhigh ranging from 20 to 38%. The pH is8.5 on average. The electric conductivityshowed values between 0.17 and 0.19dSm-1, and the organic matter contentwas low (< 1%), changing significantlyafter compost application.

The average value of total Cu was 37 mgkg-1 in the untreated soils and about 43.6mg kg-1 in treated soils, withoutsignificant differences (Table 2). The CuDTPA-extractable fraction increasedafter compost application from 5.8 to 8.1mg/kg, which represented 15% and 18%respectively of the total metal content.From the sequential analysis, the fractionlinked to the organic matter increasedfrom 22.9% to 29.5%, decreasing theresidual faction, although the latter wasstill more than 64%. The DTPAextractable fraction correlated with thefraction linked to organic matter, but thecorrelation was not significant at 95%confidence level and there was nocorrelation with other fractions.

Dr Maria Concepcion Ramosfrom the Department of Environ-ment and Soil Science,University of Lleida, Spain,describes the potential environ-mental hazard of changes inmetal concentrations of avineyard soil from addingcomposted organic waste.

Introduction

The application of composted organicwastes to improve soil physicalcharacteristics is a common practice inagricultural land – although in somecases this is a means of recycling highquantities of waste generated fromintensive animal production. Theseresidues improve soil physical propertiesby increasing soil organic matter content,and producing an enrichment of soilnutrients in a readily utilizable form.However, the composts usually containtrace elements, which at moderate levelscan be beneficial for the soil, but mighthave a negative effect at higherconcentrations. Most of the elementsadded to soils with compost areimmobilized in the soil by chelation withorganic matter and by adsorption on clayminerals; they are precipitated asinsoluble compounds, and usuallyaccumulate in the upper soil layers(Yaron et al., 1996).

The determination of total metal contentin soils is important in order tounderstand how the levels could increaseas a result of agricultural practices.However, the toxicity of metals dependsnot only on the total concentration butalso on metal mobility and reactivity. Themost common way to analyze metalmobility is by using extractants.Although there has been much effort toharmonize and standardize analyticalmethods, there is no reference method atpresent for determining each fraction.Chelating extractants such as EDTA(ethylenediaminetetraacetic acid) andDTPA (diethylenetriaminepentaaceticacid) have been extensively used (Ure etal., 1993; Brun et al., 2001, Marcet etal., 2003). Other authors advocate the useof neutral salt extractants (Gupta and


11

The average total Zn content increasedfrom 59 to 69 mg kg-1 after theapplication of compost (Table 2),although individual values near 80 mgkg-1 were also observed. The Zn DTPA-extractable fraction increasedsignificantly from 1.3 to 4.9 mg/kg,which represents 2.1 and 7.1% of thetotal content, respectively. In soil, Zn inmainly bound as oxide (10.0%) and inthe residual fraction (80%). From thesequential analysis, the percentage of theoxide bound fraction increased up to 16%in treated soils and the zinc fractionlinked to organic matter increased intreated soils from 1.2% to 2.1%. Theresidual zinc fraction decreased. Thereis a significant linear correlation betweenthe DTPA-extractable fraction and the Znfraction linked to the organic matter (r2

= 0.68) and the oxide fraction (r2= 0.69).

movement of these elements in soil is ofconcern due to potential impacts on theenvironment through surface water byrunoff. There are a few examples in theliterature of increased concentrations ofmetals in surface waters resulting fromspreading organic wastes on farmland(Boy and Ramos, in press; Farsang et al.,2005).

Therefore, metals applied to soil withcompost or other wastes contribute notonly to an increase in the total metalcontent of the soil, but also to an increasein the amount of metals that can beutilized by crops or can leach into theenvironment. This represents a potentialhazard for the development ofsustainable agriculture practice.

determination of the toxicity level.Journal of American Society forHorticultural Science, 2000, 125, 765-770.

Brun, L.A.; Maillet, J.; Hinsiguer, P.;Pepin, M. Evaluation of copperavailability to plants in copper-contaminated vineyard soils.Environmental Pollution, 2001, 111,293-302.

Farsang, A.; Kitka, G.; Barta, K.Modelling of soil erosion and nutrienttransport to serve watershedmanagement: case study in asubwatershed of Leke Velence inHungary. Geophysical ResearchAbstracts, European Geosciences Union,2005, Vol. 7.

Gupta, S.K.; Aten, C. Comparison andevaluation of extraction media and theirsuitability in a simple-model to predictthe biological relevance of heavy metalconcentrations in contaminated soils.International Journal of EnvironmentalAnalytical Chemistry, 1993, 51, 25-46.

Hammer, D.; Keller, C. Changes in theRhizosphere of Metal-accumulating

Sample Silt Clay Sand pH O.M. EC(1:5 water extract) CaCO3Point (%) (%) (%) (%) dS m-1 (%)1 42 10 48 8.6 0.47 0.17 37.82 40 12 48 8.4 0.10 0.17 38.73 45 12 43 8.6 0.59 0.19 38.74 41 8 51 8.3 0.31 0.19 20.3

Table 1: Soil characteristics of the 0-20 cm surface soil for the four positions along the vineyardslope

Discussion and conclusions

The data show an increase of total metalcontent in the soil after compostapplication. The type of metal speciationis similar in treated and in untreated soils.Cu is mainly in the organic matterfraction and Zn is bound to oxides. Thepercentage of these fractions increasedafter compost application, and theresidual fraction decreased.

The DTPA-extractable fraction, which isequivalent to the metal fraction taken upby plants, also increased after compostapplication. This fraction correspondswith the organic matter fraction for Cuand with the organic matter and oxidesfractions for Zn. Metal distributiondepends on the element, and soilproperties such as pH and soil moistureconditions (Han et al., 2001). Theseauthors noted that in arid soils thereducible oxide fraction and theorganically-bound fraction increasesafter addition of compost, although thecarbonate fraction is the most abundantin the soils they analysed.

In this study, the high pH favours thefixation of these elements to soil. The

Soil sample Cu (mg kg-1) Zn (mg kg-1)Total Cu DTPA-Cu Total Zn DTPA-Zn

P1 38.2 7.48 54 0.82P1(+) 41.7 9.1* 60.8* 4.72*P2 34.0 3.2 59.70 0.96P2(+) 43.9 6.6* 73.7* 3.6*P3 33.2 5.5 57.80 2.2P3(+) 43.9 7.3* 65.9* 5.38*P4 42.7 6.9 65.0 1.16P4(+) 44.9 9.5* 77.9* 6*AveragePi 37.0±4.0 5.8±1.9 59 ± 4 1.3±0.6Pi(+) 43.6±1.4 8.1±1.4 69 ± 10* 4.9±1.0(* significant differences between treated and untreated soils, p<0.05)

Table 2: Total metal content and the DTPA-extractable fraction for treated (Pi(+)) and untreatedsoils (Pi)

References

Boy, S., Ramos, M.C. Metal enrichmentfactors in runoff and their relation torainfall characteristics in a SpanishMediterranean vineyard soil. In A. Faz,R.Ortiz, A.R. Mermut (eds). Sustainableuse and management of soils. Arid andSemiarid Regions. Advances inGeoecology, 36 (in press)

Bucher, A.S.; Schenk, M.K.Characterization of phytoavailablecopper in compost-peat substracts and

plants evidence by chemical extractants.J. Environmental Quality, 2002, 31,1561-1569.

Han, F.X.; Kingery, W.L.; Selim, H.M.Accumulation, redistribution, transportand bioavailability of heavy metals inwaste-amended soils. In Trace Elementsin Soils: Bioavailability, Flux andTransfer, I.K. Iskandar, M.B. Kirkham(eds.), Lewis Publishers, Boca Raton,Florida, 2001, pp 145-174.

Keller, C.; Hammer, D. Metal availability


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and soil toxicity after repeated croppingof Thcaspi caernieceus in metalcontaminated soils. EnvironmentalPollution, 2004, 131, 2004, 243-254.

Lindsay,W.L.; Norvell, W.A.Development of a DTPA soil test forzinc, manganese and copper. Soil ScienceSociety of American Journal, 1978, 42,421-428.

Marcet, P.; Andrade, L.; Amoedo, R.;Fernández, E. Limiting factors for vitisvinifera L., Albariño variety productionin soils dedicated to the vineyard single-crop system. J. Int. Sci. Vigne, 2003, 37,31-38.

Pinamonti, F.; Nicolini, G.; Dalpiaz, A.;

Stringari, G.; Zorzi, G. Compost use inviticulture: Effect on heavy metal levelsin soil and plants. Communications inSoil Science and Plant Analysis, 1999,30, 1531-1549.

Tessier, A.; Campbell, P.G.C.; Bisson,M. Sequential extraction procedure forthe speciation of trace metals. AnalChem., 1979, 51, 844-851.

Ure, A. M.; Quevauviller, P.; Muntau,H.; Griepink, B. Speciation of heavymetals in soils and sediments an accountof the improvement and harmonizationof extraction techniques undertaken theauspices of the BCR of the Commissionof the European Communities.International Journal of Environmental

Analytical Chemistry, 1993, 51, 135-151.

Yaron, B.; Calvet, R.; Prost, R. SoilPollution: Processes and Dynamics,Springer Verlag, Berlin, 1996.

Zhang, S.; Shan X. Is the bioavailabilityindex applicable for trace elements indifferent types of soil? ChemicalSpeciation and Bioavailability, 2000, 12,117-123.

Dr MARIA CONCEPCION RAMOSAssociate Professor,Department of Environment and SoilScience,University of Lleida,Spain

Meeting report

been designated a Site of SpecialScientific Interest (SSSI).

In the evening, a wine reception wasfollowed by a curiously poetic keynotepresentation from Professor Brian Moss,Liverpool University, entitled“Wetlands, wolves and the courtship ofhippopotami”. His talk focussed on thedependence and interdependence of allliving things on water, and he discussedthe deterioration of wetlands in the UKand abroad, the Water FrameworkDirective (WFD), and different wetlandmanagement techniques.

The second day of the conference washeld at SOAS and consisted of a seriesof workshops on wetland management.Underpinning the discussions was therecent introduction of the WFD 2000/60/

World Wetland DayConference 2005

Wetlands: Focus on Delivery

The World Wetland Day (WWD)Conference 2005 (Wetlands: Focus onDelivery), attended by over 150delegates, was held at the School ofOriental and African Studies (SOAS),London, on 31st January and 1stFebruary, 2005. This fourth UK WWDconference was organised by CoastalManagement for Sustainability (CMS)on behalf of the Chartered Institution ofWater and Environmental Management(CIWEM). The aims of the conferencewere to bring together key organisationsin the UK involved in managingwetlands, and to promote the many usesand the biodiversity of wetlands.

The first day was based at the LondonWetland Centre (LWC) with walks ledby Wildfowl and Wetlands Trust (WWT)staff and a discussion on “creating andmanaging wetlands for wildlife andpeople”. The 40 hectare LWC is apurpose built wetland environment builton the site of four redundant Victorianreservoirs in Barnes, London. Theproject was a collaboration between theWWT, the local London BoroughCouncil and a property developmentcompany. Following its opening in May2000, the Centre has attracted residentand migratory wildfowl, includingGadwall and Shoveler ducks, and has

EC, and there were agricultural,environmental, and recreationalperspectives on managing andconserving UK wetlands, with speakersfrom the RSPB, WWT, EnvironmentAgency, English Nature, EnglishHeritage, local authorities, andenvironmental consultancies.

Weblinks

London Wetland Centre http://www.wwt.org.uk/visit/wetlandcentre/

Royal Society for Protection of Birds(RSPB) http://www.rspb.org.uk/

Water Framework Directive http://www.defra.gov.uk/environment/water/wfd/

Jo BARNES,Air Quality Unit, Cornwall College

London Wetland Centre


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Meeting reportdetermination of arsenic species (withdetection limits of around 1ngmL-1), and the application of XAS (X-ray Absorption Spectroscopy) andXANES (X-ray Absorption Near EdgeSpectroscopy) for in situ speciation ofarsenic. These techniques were used toinvestigate the metabolism of arsenicsugar species in seaweed eaten by sheepin the Orkneys. Dr Feldmanncommented that the identification andquantitative analysis of the wide rangeof arsenic-sulphur species that exists inbiological systems will open a newchapter in arsenic speciation.

In the second presentation of theafternoon, Dr Andrew Smith (MRCToxicology Unit, University ofLeicester) spoke on “Toxicogenomicapproaches to determine consequencesof metal exposure”. The traditionalconcerns of toxicologists in relation todrug responses and occupationalexposures have been replaced byinterests in carcinogenicity andneurotoxicity. In particular, theidentification of neuronal effects andtheir influence on development wereespecially important for metals such asMn, Fe, Ni, As, Pb, Hg and Cd wherelow concentrations produced low levelsof neurotoxicity. For such effects theembryo and the very young were atgreatest risk. Although mechanisticstudies of such impacts had great intrinsicvalue, he pointed out that even if theidentification of exact mechanisms oftoxicity helped our understanding of thehazards of exposure to particular species,such investigations did not always assistin the quantification of risk.

New methodologies, includingtoxicogenomics, proteomics, andmetabonomics (see ECG Bulletin, July2004), provide new testing protocols forthe toxicologist. These methods have animmense range of possibilities, but alsoproduce large amounts of data with asyet no unified method of presentation.Examining how gene transcription, thenature and quantity of proteins, or theexpression of metabolites varied after atoxicological insult might give anindication of occupational orenvironmental exposure. But theinfluence of variables such as diet

(nutritional status), polymorphisms(individual genetic type) confounded theinterpretation of results from such work.Dr Smith thought that metaboliteexpression might be the way ahead tolink exposure to toxicity and genefunction.

The closing session celebrated the workof Professor Jane Plant CBE (currentlyat Imperial College and ex-ChiefScientist at the British Geological Survey(BGS)). Her presentation was entitled“Chemicals in the Environment”.Professor Plant began by exploring themanner in which the evolution of manwas linked to the increasinglysophisticated use of chemicals. Thisusage was changing with the introductionof new technologies that involve newmodes of transport, communications,nanotechnology and similar. As man’suse of chemicals changes (and increases)so does the risk of health effects increase.Although many of the chemicals that arein the environment naturally or as aconsequence of man’s activities areessential for life, the effects of metaldeficiencies are apparent only at very lowconcentrations and exposure to a smallexcess of an essential element can easilyproduce chronic toxicity.

Professor Plant explored the way inwhich high resolution mapping of multi-element distributions in the UK couldassist in estimates of metal bio-availability and subsequent health risks.She went on to argue that in the long termonly the sustainable use of chemicalresources could resolve the issuesassociated with the increasingredistribution of geologically ‘fixed’chemicals by anthropogenic activity, andthat the best way to address suchsustainability issues was via Life CycleAnalysis (LCA).

The interlinking of toxicity studies(speciation, analysis, mechanisms, risk)with mapping of chemicals (spatialdistribution, risk assessment) and effortsto mitigate hazards and risk (sustainableuse, LCA) needs to be internationallytargeted and prioritised.

The symposium ended with a series ofquestions, some of which reflected the

The 2005 EnvironmentalChemistry GroupDistinguished Guest Lectureand Symposium

The 2005 ECG Distinguished GuestLecture and accompanying Symposiumwere held in the Council Room of theRoyal Society of Chemistry, BurlingtonHouse on March 2nd. The theme for thiswell-attended meeting was “Metals in theenvironment: estimation, health impactsand toxicology.”

Dr Jörg Feldmann, from the TraceElement Speciation LaboratoryAberdeen, University of Aberdeen,opened the meeting with a review ofarsenic metabolism. Dr Feldmanndescribed the speciation of arsenic* andhow the toxic effects of arsenic wererelated to its speciation. Although theacute toxicity of arsenic is well known,in recent years the effects of chronictoxicity linked to exposures to lowconcentrations of arsenic species havebecome more apparent. More than 70million people worldwide are exposed toarsenic, and health effects such ashyperkeratosis and skin and bladdercancer have been observed in someregions. The precise mechanisms ofarsenic toxicity are as yet unknown. DrFeldmann contrasted arsenobetaine,which is present in fish and shellfish, butis not metabolised when ingested and isexcreted unchanged in urine with noacute toxicity and no chronic effects,with arsenic III/V, which is present inwater and vegetables, has a high acutetoxicity, severe chronic effects,accumulates in hair, nails and skin, andis metabolised to DMA(III) & DMA(V)and MMA(III) & MMA(V) beforeexcretion.

Identification of the arsenic species isparticularly important when assessmentsof toxicity are made, and any analyticalprocedures need to have good speciationspecificity. The range of arsenicmetabolites (e.g. glutathione complexes,phytochelatins) demands access to avariety of species-discriminatoryanalytical methods. Dr Feldmanndiscussed the use of HPLC-ICP-MS andHPLC-ES(electrospray)-MS for the


14

concern of the delegates about thesignificant costs involved in accessingthe BGS mapping data and thedetrimental impact this has on educationand research.

More detailed accounts of the threepresentations from the ECG DGL 2005will appear in the January 2006 issue ofthe ECG Bulletin.

Dr LEO SALTER,Cornwall College,Pool, Redruth, Cornwall

*Examples of arsenic speciationName Abbreviation (Alternative Abbreviation†) Chemical formulaArsenite, Arsenous acid As(III) As(OH)3Arsenate, Arsenic acid As(V) AsO(OH)3Monomethylarsonic acid MMA(V) (MA) CH3AsO(OH)2Monomethylarsonous acid MMA(III) [MA(III)] CH3As(OH)2Dimethylarsinic acid DMA(V) (DMA) (CH3)2AsO(OH)Dimethylarsinous acid DMA(III) (CH3)2AsOHTrimethylarsine oxide TMAO (CH3)3AsOTrimethylarsine TMA(III) (CH3)3AsArsenobetaine AsB (AB) (CH3)3As+CH2COO-

Arsenocholine AsC (AC) (CH3)3As+CH2CH2OHTetramethylarsonium ion Me4As+ (CH3)4As+

Dimethylarsinoylethanol DMAE (CH3)2AsOCH2CH2OHArsenosugars X, XI, XII, XIII, XIV, XV

†Abbreviations for arsenic metabolites have not been standardised. See ‘Determination of arsenic species: A criticalreview of methods and applications, 2000–2003’, Kevin A. Francesconi, Doris Kuehnelt, Analyst, 2004, (5), 373-395.

Meeting reportPhotochemistry and reaction kinetics ofsmall molecules were the topics for thesecond session. Such data are importantfor chemical and dynamical simulationsof atmospheric chemistry, whichincreasingly require more accuratemechanisms, rate constants andArrhenius parameters. Seakins (Leeds)reviewed kinetic data on the photolysisof methyl ethyl ketone, diethyl ketone,and methyl vinyl ketone. Thesecompounds are formed from theoxidation of hydrocarbons and are alsoproduced in significant amountsbiologically. They have longatmospheric lifetimes and make asignificant contribution to the HOxbudget. Ingham (Leeds) presented theresults from a study of ClOOCl reactionswith Br, Cl and NO, which wasundertaken with Sander and Friedl fromthe California Institute of Technology.Current models over-predict ClOOCl by30% and new studies of ClOOClabsorption cross sections may benecessary. The final paper in this session(Hynes and co-workers, Miami) was akinetic and mechanistic study of therecombination of OH with NO2.

In the opening lecture on the second dayof the meeting, Platt and co-workers(Heidelberg) discussed the value of MultiAxis Differential Optical AbsorptionSpectroscopy (MAX-DOAS) foranalysing gas and aerosol distributions.This technique uses a set of slant columndensity measurements obtained with thesun as an ‘analytical light source’ tomeasure scattered light from severaldifferent elevation angles. From the data,a simple algorithm can be applied todetermine the atmospheric aerosolextinction and the absolute concentrationand mixing ratio of NO2 within theatmospheric boundary layer. Theapparatus seemed relatively simple

(miniature spectrometer, a smalltelescope, a pointing mechanism and aPC) and offers an opportunity to trackNO2 plumes at ground level which maywell be useful for statutory air monitoringpurposes.

Monks (Leicester) described plumemonitoring in the Leicester area. Jones(Cambridge) explained that thesimplified night-time chemistry of NOxis an opportunity to examine the smallscale structure of the chemistry whichoccurs in plumes. His work clearlyshowed the non-linear, non-homogenousdistribution of the chemistry in a plume,and his conclusion that one “cannotneglect the near source structure andmixing in local and regional NOx and O3budgets” may have implications forNational Air Quality Strategy monitoringprotocols. Tuck (NOAA) talked aboutsmall scale variation in atmosphericchemistry under conditions whenMaxwell-Boltzmann conditions did notapply, i.e. when there was a long tail ofhigh velocity molecules. He argued thatresearch into such phenomena wasessential for an understanding of howtropospheric warming effectedstratospheric cooling, and he used thelarge fluctuations in troposphericmethane concentrations on a smalltemporal and spatial scale as an example.

In the second morning session, George(Laboratoire d’Application de la Chimiea l’Environnement) discussed thephotoenhanced uptake of NO2 onto solidorganic compounds to give HONO (animportant source of OH), and this wasfollowed by a paper (Abbatt, Toronto)which examined the uptake of gas phasenitric acid onto ice with evidence forunsaturated surface coverage at lowpartial pressures. The interactions ofnitric acid, VOCs, ClONO2 etc. on cirrus

Faraday Discussion 130:Atmospheric Chemistry

Two-hundred delegates attended FaradayDiscussion 130 on AtmosphericChemistry at the University of Leeds heldon 11-13 April 2005.

The opening session of the meeting wasconcerned with modelling chemistry-climate interactions and the impacts ofclimate change (Pyle, Cambridge;Stevenson, Edinburgh). In a plenarylecture, “Chemistry-climate coupling:the importance of chemistry in climateissues”, Ravishankara (NOAA, Boulder)posed the questions “How does thechemical composition of the atmosphereinfluence climate and how does climateaffect chemical composition?” Severalissues arose from the papers by Pyle andStevenson, and a need was expressed fora greater understanding of:

• How stratospheric–troposphericozone exchange is affected byclimate change;

• How the behaviour of ozone in theLower Stratosphere and UpperTroposphere correlates with ElNino;

• How climate change inducedhumidity increases might influenceozone concentrations (via O(1D) +H2O → 2OH);

• The effects of convection andcirculation on tropospheric ozoneconcentrations;

• The effects of temperature ontropospheric ozone (for example viaincreased isoprene emissions fromtropical forests).


15

clouds were linked into the formation ofOH via HONO chemistry. Donaldson(Toronto) gave a paper on the uptake andreaction of atmospheric organic vapourson organic films. This topic is relevantto oxidation reactions that occur on‘urban surfaces’.

Secondary organic aerosols (SOA) wasthe subject for the afternoon sessions.Baltensperger (Paul Scherrer Institut,Switzerland) examined the dependenceof SOA growth rates on organiccompound oligomerisation processesusing α-pinene and trimethylbenzene inexperimental systems. Herrmann(Leibniz Institut) discussed SOAformation from terpenes, and indicatedthat SOA yields depended ontemperature, seed nuclei type, monomermolecular mass and monomer volatility.Using experimental and computationaltechniques, Donahue (Carnegie Mellon)examined the critical factors whichdetermine the variation in SOA yieldsfrom terpene ozonolysis. The final

session of the second day focused onNMVOC (non-methyl volatile organiccompounds) and their impact on oxidantand aerosol formation (Jenkin, ImperialCollege). Kolb (Aerodyne Research)described mobile ground levelmonitoring and the way in which it (asopposed to sparse fixed site air qualitymonitoring stations) could deal with thevariable (temporal and spatial) emissionsources which produce small areachemical gradients at ground level.McFiggans (Manchester) described theuse of a Master Chemical Mechanismwhich was a simplified representation ofthe organic component of atmosphericparticulates.

Burrows (Bremen), in the openingsession on the final day, reviewed theremote sensing of atmosphericcomposition from space and gave a clearexposition of the difficulties andapproximations involved. Jaegle(Washington) followed with a paperwhich illustrated how satellite

observations could be used to examinethe relative roles of fossil fuelcombustion, biomass burning and soilemissions as NOx sources. There is asurprisingly large contribution (22%)from soil emissions to global surface NOxemissions. Bloss (Leeds) examined theway in which the various measurementsof the oxidative capacity of thetroposphere (OH concentrations) couldbe reconciled. The final sessionexamined the hydrophilicity ofatmospheric particles (Seisel, Essen),calcium carbonate dust particles (Rudich,Weizmann) and a study of the products,mechanisms and kinetics of reactionsbetween ozone and oleic acid particles(Ziemann, Riverside).

The proceedings from FaradayDiscussion 130 will be published by theRoyal Society of Chemistry in late 2005.

Dr LEO SALTER,Cornwall College,Pool, Redruth, Cornwall

Royal Society of Chemistry Analytical DivisionAtomic Spectroscopy Group

Hilger Prize

Nominations for the 2006 HilgerSpectroscopy prize are invited. Theaward is judged on the basis of thecandidate’s contribution to analyticalatomic spectroscopy, which may be insuch fields as atomic absorption, atomicfluorescence, atomic emission, ICP-MSand X-ray fluorescence spectroscopy.The contribution need not be theoreticaland may include areas such asapplications, instrumental developmentor modification, improvement in data

handling, calibration procedures orsample preparation.

The prize is open to anyone under the ageof 35 on December 31st 2006 who is amember of the Analytical Division of theRSC and whose work involves the useof atomic spectroscopy. The applicantswill be required to submit a short summaryof their work (2 pages maximum), togetherwith a brief CV and a list of theirpublications by 31st March 2006.

The winner will receive a cash/bookprize and additionally an opportunity topresent their work at the 13th Biennial

Forthcoming meetingImpacts of climate change on air quality

National Atomic SpectroscopySymposium which will be held at theGlasgow Caledonian University from the10th to 12th July, 2006. Free registrationwill be provided to help attend this majorconference on atomic spectroscopy.

APPLICATIONS SHOULD BE SENT,PREFERABLY IN ELECTRONICFORM, BY 31st MARCH 2006, to theHonorary Secretary of the AtomicSpectroscopy Group, Dr. A. Fisher, Schoolof Earth, Ocean and EnvironmentalSciences, University of Plymouth, DrakeCircus, Plymouth, Devon, PL4 8AA.e-mail: [email protected]

The 2006 EnvironmentalChemistry GroupDistinguished Guest Lectureand SymposiumLondon, March 2006‘Clear science demands prompt actionon climate change say G8 scienceacademies’

In a united attempt to alert politicalleaders to the existence and

consequences of climate change, the G8Science Academies issued a jointstatement on June 7th 2005. Thestatement calls on the G8 nations to:“Identify cost-effective steps that can betaken now to contribute to substantial andlong-term reductions in net globalgreenhouse gas emissions.” And to,“recognise that delayed action willincrease the risk of adverseenvironmental effects and will likelyincur a greater cost.” The 2006 ECGDGL and Symposium will examine one

aspect of the consequences of climatechange - the impacts of climate changeon air quality. The 2006 DistinguishedGuest Lecturer will be Professor MikePilling from the University of Leeds.Further details of this event will be givenin the next issue of the ECG Bulletin.

Weblink: Joint Science Academies’statement: ‘Global response to climatechange’ http://www.royalsoc.ac.uk/displaypagedoc.asp?id=13057


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Meeting reporta presentation on ‘Exposure measure-ments of indoor ultra fine particles: apilot study on the night-time patterns’.Elevated ultrafine particle concentrationswere observed during indoor activitiessuch as cooking and vacuum cleaning,but the particulate level decreased duringzero activity (sleep). Still indoors, IvanGee (Manchester) highlighted thatcarpets in houses with inhabitants whosmoke were a source of endotoxins.

Alex Ledbrooke (Cornwall College)reviewed the ‘Cornwall Air QualityStrategy: air quality issues in an isolatedrural area’. A poor road infrastructurewas of particular concern for its effecton localised air quality.

Session 3: Exposure measurement andmodelling (2)

The exposure measurement andmodelling session continued with AlisonTomlin (Leeds) who talked about‘Factors influencing exposure to trafficrelated pollutants in urban streets’. Bymonitoring traffic characteristics,correlations were found between CO

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and vehicle occupancy. The resultsshowed congestion to be a biggercontributing factor to elevated pollutionconcentrations than vehicle numbers.Tomlin also presented models ofpollution in streets, and described theeffects of topography, wind direction andtraffic emissions.

Susan Hodgson (Imperial College,London) and Richard Mohan (ChemicalHazard and Poisons Division, London)both described dispersion modellingaround a point source: a Chlor alkali plantin Runcorn and a landfill site respectively.

Session 3: Ultrafine seminar (1)

Roy Harrison (Birmingham): ‘Formationand dispersion of ultrafine particles:composition, lifetime, monitoring andmodelling’. Anthony Seaton (Institute ofOccupational Medicine, Edinburgh),‘The ultrafine hypothesis after ten years’.

Session 4: Ultrafine seminar (2)

Ken Donaldson (Edinburgh): ‘Reactionsof ultra fine particles and biological

systems’. Martin Meadows (DEFRA):‘Policy implications’.

Session 5: Mechanisms

Martin Wilson (Napier University,Edinburgh): ‘Nanoparticle and metalinteractions and their impact on lungtoxicology’. Michael Routledge Leeds):‘DNA damage and mutations induced byurban particulate matter’. Sarah Kemp(Imperial College, London): ‘Effects ofnanoparticles on mediator release byprimary human alveolar epithelial cellsand macrophages’.

Session 6 : Epidemiology and humanhealth (1)

Hazel Jones (Imperial College London)discussed the use of Position EmissionsTomography (PET) to assess the effectsof smoking on the lungs. This non-invasive technique allowed repeatedexamination of the lung tissue, whichrevealed that ‘inflammatory cell activityin the lungs of smokers is modulatedeven by a relatively modest acute insult’.Richard Atkinson (St Georges’ HospitalMedical School, London) of theAPHENA (Air Pollution and Health: aCombined European and NorthAmerican Approach) project presentedthe ‘results of analyses of hospitaladmissions’. The work highlighted aneed for sensitivity analysis in studies ofthe short-term health effects of particlesand ozone on respiratory hospitaladmissions. Ben Barrett (King’s College,London) then talked about the proposedinvestigation into the health impacts ofthe London Congestion ChargingScheme. This is to be a three-year studystarting in 2005.

Session 7: Epidemiology and humanhealth (2)

Stephen Bremner presented results of astudy linking hospital admissions andparticle species. This involved loggingadmissions, age, sex, diagnosis etc. withinformation downloaded daily from theinternet. The results were inconclusive,although sulphate and ozone weredeemed to be associated with anincreased risk of admissions across thebroad range of diagnostic and age subgroups.

9th Annual UK ReviewMeeting on Outdoor andIndoor Air Pollution Research

University of Leicester, 20-21 April 2005

Over the past nine years, UK air pollutionresearch groups have participated inannual meetings hosted by the MRCInstitute for Environment and Health(IEH), Leicester. This year’s meeting wasattended by 70 delegates with 22 speakersand 14 poster presentations. Somehighlights are summarised below. The fullproceedings of the 9th Annual UK ReviewMeeting on Outdoor and Indoor AirPollution Research are available at http://www.le.ac.uk/ieh/pdf/W22.pdf

Session 1: Atmospheric chemistry,exposure measurement and modelling

The first session was opened by MonicaPrice (Sunderland), who made a‘Comparison of black smoke and PM10measurements from co-located monitorsat three UK sites’. Price argued blacksmoke (BS) to be a better indicator ofhealth effects than particulate matter(PM). On a related theme, Fu-MengKhaw (Newcastle upon Tyne) presenteda study into the relationship betweenhistorical SO2 levels and black smokeexposure in North East England. Thestudy found SO2 could be used as apredictor for BS, and will be used as partof a larger project to estimate long-termexposure to air pollutants in a cohort of1142 babies born in Newcastle uponTyne, in May and June 1947 – theNewcastle Thousand Families Cohort.

Abhishek Tiwary described theUniversity of Nottingham’s research intohedgerow effects on aerosol filtration anddispersion. The work has applicationsfor mitigating pesticide drift fromfarmland to residential properties.Porous hedges such as the Holly bushproved to be more efficient at filteringparticles from air than the denserhedgerows such as Yew.

Session 2: Exposure measurement andmodelling (1)

Sirinath Jamieson (Imperial College,London) began the second session with


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Christina Yap reported an investigationinto long term exposure to air pollutionin Scotland. The study has lasted for 22years and has involved 22,000 subjectsin an area where detailed records of blacksmoke exist. The research found‘convincing evidence’ of a link betweenexposure and cancer. There were,

however, missing data, and variablessuch as house and traffic density werenot taken into consideration. Thisinformation will be added to the research,which will be reassessed to clarify thefindings.

The final presentation of the conference

was by Roseanne McNamee(Manchester) who described aninvestigation into whether or not‘cardiopulmonary patients are moresusceptible to pollutant-relatedmortality’.

A. LEDBROOKE, Air Quality Unit,Cornwall College

Comment: Fish stocks, endocrine disruptors, and global warmingFollowing an article onendocrine disruptors in theprevious issue of the ECGBulletin, Alan Wisemancomments on other environ-mental threats to fish stocks.

The laudable article in the January 2005issue of the Environmental ChemistryGroup Bulletin (pp 4-6) by E. M. Hilland C. M. Tyler, “Endocrine disruptionand UK river fish stocks”, emphasisedthe accumulation in the bile of oestrogensand mimics (104 – 105 fold). Using theYES bioassay (recombinant yeastcontaining oestrogen receptor) withreverse phase HPLC/MS techniques, arange of oestrogens were identified in theimmature rainbow trout.

Nevertheless, especially where stocks ofthe gudgeon (Gobio gobio) arethreatened by endocrine disruptors, other

. . . Elizabeth Hill replies:There are numerous stresses affectingfish population in UK rivers, andendocrine disrupting chemicals are oneof them. The finding that intersex fish ineffluent-contaminated waters havereduced fertility suggests the possibilityof deleterious population changes in anumber of UK fish species (Jobling etal., Biology of Reproduction, 2002, 67,515-524). In addition, the impact ofclimate change, resulting in less dilutionof effluents (some of which are barelydiluted in receiving waters in summer)are likely to exacerbate this type ofpollution unless additional wastewatertreatment technologies are deployed.

Wiseman makes an important point thatdepletion of oxygen levels in rivers due

to climate change and BOD may alsoaffect survival of sensitive fish species.In addition, the reports that sub-lethallevels of hypoxia can also impair fishreproduction and embryonicdevelopment raises further concern onthe future health of fish populations inrivers (Wu et al., Environmental Scienceand Technology, 2003, 37, 1137-1141;Shang and Wu, Environmental Scienceand Technology, 2004, 38, 4763-4767).These stresses combined with inputs ofan array of effluent-associatedxenobiotics – including somepharmaceuticals, the loss of habitatdiversity, and the effects of damming(weirs) – which inhibit fish movement,all suggest that river environments arestill amongst the most vulnerable

ecosystems in the world with regard toanthropogenic impacts.

E. M. HILL,University of Sussex,June 2005

factors may determine the survivaloutcome! These factors include theeffects of water temperature on dissolvedoxygen concentration (DOC). DOC islower at higher temperatures, andbiological oxygen demand (BOD) of theeffluent waters will modulate theoutcome (Lynch and Wiseman, 1998).

Furthermore, global warming,somewhere in the wide range of 2 – 11˚C in this century, has been predicted bya variety of models set up in computersworldwide (Stainforth, Alna,Christensen, Collins, Faull et al. 2005).Moreover, survival chances of individualspecies of fish, such as the river trout,should be extrapolated now toaccommodate the ongoing globalwarming (from an anthropogenic causeor otherwise) associated with the risingatmospheric level of greenhouse gases,such as carbon dioxide and methane. Inaddition, presently pertinent data will be

replaced very soon by updated findingsof further investigations of the pollutioncaused by endocrine disruptors such asoestrogens and mimics.

References

Lynch, J.M. and Wiseman, A. (eds.),Environmental Biomonitoring: TheBiotechnology Ecotoxicology Interface,Cambridge University Press, Cambridge,1998.

Stainforth, D.A., Alna, T., Christensen,C., Collins, M., Faull, N., et al.Uncertainty in predictions of climateresponse to rising levels of greenhousegases. Nature, 2005, 433, 403-406.

Dr ALAN WISEMANc/o School of Biomedical & MolecularSciences, University of Surrey,Guildford, GU2 [email protected]


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Meeting reporta low level of metabolism and relativepersistence. Seven otherpharmaceuticals were also found. Thestudy concluded that most sewage worksrelease pharmaceuticals in measurableamounts, with variations in individualsewage treatment works.

Alex Tait (Veterinary MedicinesDirectorate) outlined European Unionenvironmental legislation for human andveterinary pharmaceutical products,which are covered by Directives 2001/83/EC (amended 2004/27/EC) and 2001/82/EC (amended 2004/28/EC),respectively. Some veterinary medicineshave been refused MarketingAuthorisation on the basis ofenvironmental safety whereas manyhuman medicines have been approvedwithout an environmental assessmentdue to the absence, at present, ofappropriate guidelines.

Len Levy (MRC Institute forEnvironment and Health, University ofLeicester) reviewed the indirect effectsof veterinary medicines on consumers.The main concerns are the long-term fateof these products in the environment andrisks to health, which result from indirectexposure. Around 90 compounds wereselected for their potential impact onhuman health using a priority scheme.Of these, 31 compounds were identifiedas being of particular concern. The rangeof compounds was expanded to 48 toinclude some that are not licensed forveterinary use but which find their wayinto the environment. Low or no effectlevels for significant endpoints (e.g.neurological, developmental, mutagenicand carcinogenic effects) were estimatedusing literature data relevant to low-level,long-term exposure. The overall aim isto assess the likely exposure of humansto the priority veterinary medicines.Combining the exposure data withhazard information will allow assessmentof risk. Refinements to the model willinclude additive effects of compoundswith similar health effects andconsideration of sensitive subgroups inthe population.

Kevin Thomas (CEFAS) gave a talk onthe occurrence of human pharm-aceuticals in the UK aquatic

environment. Measurements (HPLC-ESI MS) were carried out in wastewaterworks, rivers and estuaries for the 500most used pharmaceuticals. Of the fivesewage works monitored, ten of thetargeted pharmaceuticals were identified.Ibuprofen had the highest measuredenvironmental concentration (MEC) atca.3 mg L-1. Upstream samples wereclean whereas discharge and downstreamsamples showed similar relativeabundances. Eight of the targetedcompounds were identified in receivingwaters, with ibuprofen again at thehighest MEC (1 mg L-1). Analysis of sixstations along the Tyne estuary revealedthe presence of nine of the targetedcompounds and showed that Howdenwater treatment works accounts for 80%of the effluent that goes into the Tyne.

Katherine Fenner (EAWAG,Switzerland) outlined the challenges inexposure modelling for pharmaceuticals.The main focus of modelling studies forpharmaceuticals in the environment is thetransfer from soil/sediment/sludge togroundwater. There is little guidance onhow to estimate elimination from sewagetreatment plants and there is little detailedknowledge of the pathways ofbreakdown. The main uncertainty inexposure modelling is in the treatmentof pharmaceutical release and transportinto water systems from sludge ormanure that has been applied to soils.

Most exposure models assume thatsorption is dominated by adsorption toorganic matter. However,pharmaceuticals associated with sludgeand soil show little correlation betweenlog Koc and log Kow, indicating thatorganic carbon content is not a gooddescriptor to model sorption. Thus,sorption is dominated by polar andcharged interactions associated with thepolar nature of the pharmaceuticals.

Liz Wellington (University of Warwick)discussed the impacts of clinical and non-clinical usage of antibiotics and biocideson environmental reservoirs and mobilityof resistance genes. Bioavailability ofpharmaceuticals in the environment hasthe potential to affect natural microbialpopulations through the development ofresistance genes. The prevalence of

Pharmaceuticals in theEnvironment

Organised by the SCI BioActiveSciences group in association withJPAG, RSC and SETAC-UK, thismeeting was held in March 2005 at theSociety of Chemical Industry, BelgraveSquare, with an attendance of about 120.

The topic for the meeting was introducedby Mark Cronin, (Liverpool JohnMoores University), who noted thatalthough there are data on the presenceand distributions of some pharma-ceuticals in the environment, relativelylittle is known of their biological effectson ecosystems.

Emma Pemberton (EnvironmentAgency) explained how the types ofpharmaceuticals that do enter theenvironment are related to their overallusage. Among the 5,500 activepharmaceutical ingredients approved forhuman use, the top 50 pharmaceuticalsby usage include paracetamol, lactulose,ibuprofen, acetylsalicylic acid, andamoxycillin, which are all used at levelsof around 100 tonnes/annum. The nextlevel includes ranitidine, cimetidine,carbamazepine, and erythromycin whichare used at levels of between 10-100tonnes/annum. By contrast, only about450 veterinary medicines are authorised.Usage of antimicrobial medicines isaround 450 tonnes/annum (ca. 50% ofwhich is accounted for by tetracycline),organophosphorus sheep dip (50.2tonnes/annum), coccidiostats (214tonnes/annum) and growth promoters(13 tonnes/annum).

For human pharmaceuticals, the primaryroute into the environment is throughsewage treatment plants – the combinedeffect of excretion and improper disposalof unwanted drugs. Most sewagetreatment works are likely to dischargelow levels of pharmaceuticals, and inseveral cases measurable amounts arepresent in the receiving waters. In a UKstudy, twelve compounds weremonitored in sewage works at low flowconditions. Ibuprofen levels were verymuch greater in effluent and in receivingwaters than other compounds, reflecting


19

microbial resistance to pharmaceuticalsindicates that delivery of compounds viamanure and industrial effluent impactson resistance gene reservoirs. Theprevalence and spread within indigenousbacteria suggests the involvement ofplasmids. The differences in resistancequotients between natural soil bacteriaand bacteria in chicken litter are vast,indicating active development inantibiotic augmented situations.

Two sites, an arable field deliberatelypolluted with antibiotics and a heavilypolluted effluent treatment reed bed at atextiles works, were examined for thespread of antibiotic resistance. Pig slurryfrom tylosin-fed pigs was amended withsulfachloropyridazine and oxy-tetracycline before being spread on thearable field. Around 65% of bacterialisolates contained a knownsulphonamide resistance gene.Examination of bacterial isolatesrevealed a range of soil bacteria with amobile R plasmid. Further workconfirmed the transfer of genes to soilbacteria via plasmids and integrons.Only isolates from the reed bed itselfshowed the presence of a class 1 integronthat was disseminated widely among theaquatic bacteria. (Integrons are mobileDNA elements with the ability tocapture genes, notably those encodingantibiotic resistance, by site-specificrecombination).

The presence of qacE genes andantibiotic resistance genes indicates thatpollution from quaternary ammoniumcompounds such as detergents andsurfactants increases selection pressureand facilitates the spread and persistenceof antibiotic resistance among naturalbacterial populations.

In a talk on ecotoxicity tests forpharmaceuticals, Tim Williams(AstraZeneca) suggested that the focusshould be on the long-term environ-mental effects of pharmaceuticals.Evaluation of impacts based on acutedata is not appropriate. The base data setis the Phase II Tier A data involvingecotoxicological testing for algal growthinhibition (Organisation for EconomicCo-operation and Development; OECD201), Daphnia reproduction test (OECD211) and fish early life-stage test (OECD210). For Phase II Tier B assessment,log Kow values ≥ 4 are used as a criterion

for bioaccumulation and indicate arequirement for the analysis of terrestrialeffects. Given that the timescalesinvolved in order to achieve regulatorycompliance can be long, it is necessaryto include the testing during the drugdevelopment phase.

Early screening of candidate drugs canbe performed prior to seeking regulatorycompliance. This necessitates theselection of appropriate tools for theassessment, good speed and efficiency,and predictions of potential long-termeffects. The real question is “can weaccount for ecotoxicology in drugdesign?” Accordingly, the currentdirection of research is to:

• Understand the mode of action andmechanisms of effect;

• Determine differences betweendifferent classes of organism;

• Make better use of mammalian datato predict ecological responses, and

• Use “direct” testing strategies.

For example, the impact of tamoxifencitrate on life cycle of fathead minnow(Pimephales promelas) has beenexamined. The life cycle and size of thefathead minnow is such that it is possibleto test to maturity in about one year, andvarious different growth stages andindicators are examined. In particular,the presence of the female sex hormonevitellogenin in male fish is used as amechanistic signpost for estrogendisruptors and can contribute to overallbody of evidence required to identify asignificant impact.

Alistair Boxall (University of York/Central Science Laboratory) concludedthe scientific programme with a talk onthe fate of pharmaceuticals in theenvironment. Pharmaceuticals enter thewider environment through a variety ofroutes including biosolids (sludge, slurry,direct excreta) and irrigation. A keyconsideration is their fate with respect torelease into soils. Detailed studies havebeen carried out with three antibacterialcompounds representative ofsulfonamide, tetracycline and macrolideantibiotics, respectively.

Sulfachloropyridazine had a low sorptioncoefficient (Kd) in soil and soil/slurry,indicating it to be highly mobile.Oxytetracycline had a high Kd and hencewas moderately persistent. Tylosin wasnot detected in any of the soil samples.The nature of the matrix was also shownto be important. Thus, in sandy soilsulfachloropyridazine was found to havea half-life of about 6 days, indicating alower potential to leach to groundwater.A marked pH dependence of Kd wasnoted for oxytetracycline. The macrolidetylosin exhibited a half-life of less than2 days in slurry but was persistent insoils, having sorption characteristicsintermediate betweensulfachloropyridazine andoxytetracycline. In general, metaboliteswere found to be less sorptive than theparent compounds.

The test compounds were applied to thetest soils in pig slurry, and leachate wasmonitored over a period of four months.At the end of that time the soil was alsoanalysed. Only sulfachloropyridazinewas observed in the soil or the water,indicating that oxytetracycline andtylosin will not leach to groundwaterfollowing slurry application. The affinityof sulfachloropyridazine for the aqueousphase is important to its mobility.Although antibiotics are released to soilsand have the potential to persist for sometime, their transport to surface waters andgroundwater is variable and where thisdid occur, the environmentalconcentrations were lower than the effectconcentrations.

Dr BRENDAN KEELY,Department of Chemistry,University of York


Recent books on the environment and on toxicology at the RSClibrary

European Centre for Ecotoxicology andToxicology of Chemicals, Brussels 2004,ISBN/ISSN: 0773633946

Glyoxal(Concise International ChemicalAssessment Document No. 57)

World Health Organization, Geneva,2004, ISBN/ISSN: 924153057X

IARC Monographs on the Evaluationof Carcinogenic Risks to Humans(IARC Monographs Vol. 84)

World Health Organization, Geneva,2004, ISBN/ISSN: 9283212843

Introduction to EnvironmentalAnalysis

R. Reeve, J. Wiley, Chichester, 2002,ISBN/ISSN: 0471492957

Local Authority Health and SafetyEnforcement

C. N. Penn, Shaw & Sons Ltd., Crayford,2005, ISBN/ISSN: 0721916503

Soil and Sediment Risk Assessment of

The following books and monographs onenvironmental topics, toxicology, andhealth and safety have been acquired bythe Royal Society of Chemistry library,Burlington House, during the periodJanuary to May 2005.

Asphalt (Bitumen)(Concise International ChemicalAssessment Document No. 59)


Chemical Science Priorities forSustainable Energy Solutions

Royal Society of Chemistry, Cambridge,2005

Chloroform(Concise International ChemicalAssessment Document No. 58)


1-Chloro-1,2,2,2-Tetrafluoroethane(HCFC 124), 2nd edition(ECETOC Joint Assessment ofCommodity Chemicals (JACC) No. 46)

Organic Chemicals(ECETOC Technical Report No. 92)


Targeted Risk Assessment(ECETOC Technical Report No. 93)

European Centre for Ecotoxicology andToxicology of Chemicals, Brussels 2004,ISBN/ISSN:ISBN/ISSN: 0773807293

The Toxicology of Glycol ethers andits Relevance to Man(ECETOC Technical Report No. 95)


Whole Effluent Assessment(ECETOC Technical Report No. 94)


This issue of the ECG Bulletin was printed by SurePrint, Haywards Heath, West Sussex RH16 3NG Tel: 01444 456673

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