Ecotoxicology and Environmental Safety 42, 57—61 (1999)

Environmental Research, Section B

Article ID eesa.1998.1726, available online at http://www.idealibrary.com on

Comparison of Foliar and Stem Bioaccumulation of Heavy Metalsby Corsican Pines in the Mount Olympus Area of Cyprus

F. B. PyattDepartment of Life Sciences, The Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, United Kingdom

Received December 10, 1997

Early anthropogenic metalliferous activity on the island ofCyprus is outlined. Samples of Corsican pines, obtained fromboth a largely uncontaminated (control) and a metalliferous partof the Mount Olympus area of Cyprus, were analyzed by meansof X-ray microanalysis. A total of 21 ions were recorded from thesamples; in the contaminated site manganese, cobalt, nickel,copper, zinc, silver, and tin were bioaccumulated by the needles,while copper, zinc, and gold were bioaccumulated by the stems.Some elements, e.g., copper, were more positively bioac-cumulated than others. Some implications of the findings arediscussed. ( 1999 Academic Press

Key Words: Cyprus; bioaccumulation; heavy metals; pine.

INTRODUCTION

The island of Cyprus occupies an area of 9250 km2 and islocated in the eastern Mediterranean some 97 km to thewest of Syria. Civilization on Cyprus can be traced to theNeolithic Age (7000—3900 BC), but it was during the Chalco-lithic Age (3900—2500 BC) that the exploitation of the copperpresent on the island commenced. By the Bronze Age(2500—1050 BC) copper was being more systematically ex-ploited and this brought enhanced wealth to Cyprus; tradeat this time with the Near East, Egypt, and the Aegeancontinued to develop; after 1400 BC, Mycenaeans fromGreece reached the island, perhaps in the role of merchants.More recently, the importance of the copper deposits on theisland led, in 1912, (http://www.cyprusamax.com/about/his-tory.htm) to American investors forming a company knownas Cyprus Mines to explore for minerals on Cyprus; sub-sequently they located a large, rich copper deposit amongthe ancient Roman copper workings.

The current investigation was centered on the MountOlympus (altitude 1951 m) region in the Troodos area to thenorth-northwest of Lemesos (Limassol). The Troodosmountains were formed initially as an ocean ridge, at depthsof 2 to 4 km, beginning about 85 to 75 million years ago(Upper Cretaceous period). Further north is located the

57

Alphine chain of which the Girne range is a part which wascaused by the folding and fracturing of the sedimentaryrocks that formed on the Tethys ocean floor between Africaand Eurasia.

The amounts of copper present in Cyprus have recentlyattracted further attention. Thus, R. Gregoriades (personalcommunication) noted that copper mining has just recom-menced near the village of Skouriotissa (due north of thesampling sites, q.v., in the Troodos mountains) and theventure, it is anticipated, will yield copper to the value ofapproximately $20 million annually.

Bioaccumulation of substances, including heavy metals,has been reported by a number of workers. Thus, Bowelland Ansah (1994) carried out geochemical mapping of soilsand selected plants in Ghana and noted that the distributionof the essential nutrients Co, Cu, and Mn was largely con-trolled by bedrock geology, while the geochemical disper-sion of Ca, I, Fe, Mg, Mo, P, K, Se, Na, and Zn was modifiedby soil and hydromorphic processes. They noted that Fe,Mn, and Co were largely fixed in the soil mineral fraction,Co, Cu, and Mn were preferentially concentrated in grasses,and Mo and Se were concentrated in browse plants. Cuuptake was found to be antagonistic to Fe, Mo, and Znaccumulation in all the plants they sampled.

Samecka-Cymerman and Kempers (1996) noted that thehighest concentrations of Cd, Co, Cr, Hg, Ni, Pb, and Zn inaquatic macrophytes exceeded the average values found inplants collected from background reference sites. Similarly,Jonnalagadda and Nenzou (1997), working on abandonedmine dumps in eastern Zimbabwe, recorded enhanced con-centrations of arsenic in the leaves of Amaranthus hybridus.

EXPERIMENTAL PROCEDURE

Fresh material of needles (leaves) of identical size togetherwith samples of 4-year-old wood from the stems of pineswere collected from the two sites at a height of 2 m aboveground; the sites in the Mount Olympus region were locatedapproximately 3 km apart. All the young trees used were of

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58 F. B. PYATT

approximately the same height and exhibited comparablevitality. Soil samples were removed by means of a stainless-steel trowel after the superficial vegetation and plant debrishad been removed; samples from within the soil mass weresubsequently analyzed. The sites were (a) below Olympus(control site) and (b) below Olympus where copper contami-nation of the substratum was evident (contaminated site).

The samples were transported to the laboratory in cleansterile tubes and the vegetation samples were thoroughlywashed by prolonged agitation in deionized water to re-move superficial deposits that may have been transportedvia the atmospheric environment. Four replicates were em-ployed and the maximum variation between the sampleswas $5%. The procedure of X-ray microanalysis for theanalysis of the samples has been described by Pyatt andLacy (1988). Essentially the technique can be summarized asfollows: Each sample was individually mounted on a 13-mm-diameter carbon stub and secured by means of conduc-tive carbon cement; Duron spray was applied to eliminateproblems caused by electrostatic charges. The samples werethen transferred to a Cambridge Stereoscan 600 and ana-lyzed by electron probe X-ray microanalysis with a LinkSystem 860 series 2 computer using a ZAF-4 program. Inthe process of X-ray microanalysis, an electron beam strikesthe solid specimen and a number of interactions occurincluding the production of X-rays, which are detected by

TABLElement Content (%) of Soil and Pine Tissues

Site a

Element Soil Needles Stems Mean

Na 4.4 2.4 5.7 4.05Mg 2.2 1.5 1.8 1.65Al 23.9 16.9 15.3 16.1Si 52.3 38.0 29.7 33.85P 0 0.3 0.2 0.25S 0.02 3.3 1.4 2.35Cl 0.07 6.0 5.9 5.95K 0.6 2.2 2.3 2.25Ca 9.5 23.1 33.0 28.05Ti 0.03 0.3 0.3 0.3V 0.03 0.01 0.1 0.055Cr 0.1 0 0 0Mn 0.1 0.2 0.2 0.2Fe 6.3 4.3 2.6 3.45Co 0.003 0.1 0.08 0.09Ni 0.2 0.4 0.7 0.55Cu 0.001 0.1 0.02 0.06Zn 0.03 0.2 0.2 0.2Ag 0.07 0 0.2 0.1Sn 0.05 0.05 0.1 0.075Au 0.1 0.6 0.2 0.4

aMean"vegetation mean. Site a"control site, site b"contaminated sit

a lithium drifted silicon detector and are passed on toa multichannel analyzer. Suitable areas on each sample(10,000 lm2) were selected for analysis using the microscopevisual display monitor and analyzed at a magnification of500] for 100 s of live time at 25 kV (electron beam energy).This procedure analyzes only material from sodium upwardin the Periodic Table but has proved particularly useful inside-by-side comparisons as was required in this particularinvestigation. Ten subsamples of each of the four replicateswere used in each case.

RESULTS

The results are presented in Table 1. A total of 21 ele-ments/ions were recorded; the elemental ranking variedwith the sample type:

Site a—control, soil:

Si'Al'Ca'Fe'Na'Mg'K'Ni'Cr/Mn/Au'Cl/Ag'Sn'Ti/V/Zn'S'Co'Cu.

Site a—pine needles:

Si'Ca'Al'Cl'Fe'S'Na'K'Mg'Au'Ni'P/Ti'Mn/Zn'Co/Cu'Sn'V.

E 1from the Mount Olympus Area of Cyprusa

Site b

Soil Needles Stem Mean

0.9 6.6 3.5 5.0518.6 3.4 5.0 4.20 3.4 9.3 6.35

66.0 14.9 39.4 27.150 0 0.04 0.020.1 1.8 1.3 1.550.2 11.0 2.8 6.90.07 6.0 1.2 3.60.02 44.3 32.0 38.150.03 0.4 0.2 0.30.001 0.05 0.04 0.0450.5 0.3 0.08 0.190.2 0.7 0.2 0.45

11.7 1.2 3.6 2.40.07 0.7 0.03 0.3651.2 1.4 0.4 0.90.005 0.9 0.1 0.50.02 0.5 0.05 0.2750.3 0.9 0.1 0.50.2 1.7 0.2 0.950.002 0 0.3 0.15

e.

BIOACCUMULATION BY CORSICAN PINES IN CYPRUS 59

Site a—pine stems:

Ca'Si'Al'Cl'Na'Fe'K'Mg'S'Ni'Ti'P/Mn/Zn/Ag/Au'V/Sn'Co'Cu.

Site b—contaminated, soil:

Si'Mg'Fe'Ni'Na'Cr'Ag'Cl/Mn/Sn'S'K/Co'Ti'Ca/Zn'Cu'Ag'V.

Site b—pine needles:

Ca'Si'Cl'Na'K'Mg/Al'S'Sn'Ni'Fe'Cu/Ag'Mn'Co'Zn'Ti'Cr'V.

Site b—pine stems:

Si'Ca'Al'Mg'Fe'Na'Cl'S'K'Ni'Au'Ti/Mn/Sn'Cu/Ag'Cr'Zn'P/V'Co.

These absorption sequences are somewhat different fromthat recorded for Silene armeria, Salix spp., and Populusnigra in Italy (Dinelli and Lombini, 1996) which wasZn'Co'Cu'Ni'Fe'Cr.

DISCUSSION

Dinelli and Lombini (1996) investigated plants growing ina copper spoil tip area in the northern Apennines of Italyand noted that such areas possess high concentrations ofiron, magnesium, copper, chromium, cobalt, and nickel,which were all also recorded from the sites used in Cyprus(Table 1). However, the observed absorption rankings weresomewhat different from that recorded for Silene armeria,Salix spp., and Populus nigra in Italy (Dinelli and Lombini,1996) which was Zn'Co'Cu'Ni'Fe'Cr.

In site a, which served as the control, there was noevidence of bioaccumulation of chromium by either theneedles or the woody tissue of the stem; the soil chromiumvalue amounted to 0.1%. However, in the case of the con-taminated site (b) there was enhanced bioaccumulation ofchromium by the needles (0.3%) and stems (0.08%) ascompared with the control site, but the soil concentrationwas enhanced with a value of 0.4% greater than that in thecontrol site. Thus, there is evidence of movement of chro-mium into the pine plants but the concentrations in theselected plant tissues did not exceed those in the soil. Raiet al. (1995) worked with two species of aquatic macro-phytes and found that they possessed an enhanced ability tobioaccumulate chromium (and cadmium) and noted thatthe toxicity was greater when both elements were present.

The concentration of manganese in the soils varied from0.1% in site a to 0.2% in site b. There was evidence of slightbiomagnification in the stems at both sites where the valuewas 0.2%. This was identical to the pine needle value in sitea, whereas in the contaminated site the value at 0.7%

indicated a significant amount of bioaccumulation by theneedles.

Cobalt (Table 1) displayed evidence of bioaccumulationby both the needles and the stems (latter applied to materialfrom the control site only) of Corsican pine; in both sites thehighest concentration occurred in the needles of the plantsand, in the case of plants growing in the contaminated area,a 10-fold increase in concentration as compared with thesoil value was evident. Palit et al. (1994) noted that thistransitional element is an essential component of severalenzymes and coenzymes and that its lower mobility inplants restricts its transport from stems to leaves. It is thusconceivable that the enhanced concentrations found in theneedles, in the current study, is largely a consequence ofatmospheric erosion of areas contaminated with cobalt.Palit et al. (1994) also indicated that a high level of cobaltwill induce iron deficiency in plants; this was found to be thecase in the current investigation (Table 1) where the needleswith the higher cobalt concentration (site b) had a markedlydiminished iron concentration as compared with needlesfrom plants with a lower cobalt concentration. However,a morphological and anatomical examination of the leavesfailed to detect any evidence of clearly defined chlorosis.

In the case of nickel from the less contaminated site therewas a slight degree of bioaccumulation by the needles (effec-tively resulting in a doubling of the soil concentration); thiswas more pronounced in the woody tissue of the stem. Theresults from the contaminated site are, however, more diffi-cult to interpret: the soil value is enhanced, but while bioac-cumulation has occurred in the needles this was not toa marked extent as compared with the soil value. However,in the case of material from the contaminated site, the stemvalue was considerably less than found in the uncon-taminated site; whether translocation to other tissues hasoccurred is currently uncertain.

The values obtained for copper provide a better fit: thesoil values varied from 0.001% (site a) to 0.005% at themore contaminated site (b). In site a the stems exhibiteda 20-fold increase in concentration whereas the needlesexhibited a 100-fold increase. In the case of material fromthe contaminated sites the values were a 20-fold increase inconcentration for stems and a massive 180-fold increase inconcentration for needles. Moustakas et al. (1997) similarlyobserved that the copper concentration of wheat plantsgrowing in a copper-contaminated area was 3.5 times higherthan that in the control. It is hence apparent that the pineplants of Cyprus have an enhanced ability to bioaccumulatecopper from the pedosphere and this is in agreement withthe findings of Arduini et al. (1996) who investigated copperand cadmium uptake by 2-week-old seedlings of Pinuspinea, P. pinaster, and Fraxinus angustifolia; they recordedmarked bioaccumulation of copper.

Zinc bioaccumulated equally (6.6-fold increase in concen-tration from the soil value) by the needles and stems in site a;

60 F. B. PYATT

in site b there was a slight enhancement of zinc by the stemsas compared with the soil value but a 25-fold increase inconcentration by the needles was apparent. Luwe (1995),in work with beech stands, indicated that there was con-siderable translocation of Zn (and Cd) between below-and above-ground organs of Mercurialis perennis andPolygonatum multiflorum. Bioaccumulation of copper andzinc was investigated in Minuartia verna growing on heavymetal-polluted soils of medieval mine wastes by Neumannet al. (1997), who recorded bioaccumulation of copper andzinc by the leaves; this is in agreement with the currentfindings reported in this paper.

The silver values for the soils varied (0.07—0.3%) betweenthe soil in the two sites; the silver content of the soil in siteb was markedly enhanced, and whereas the needles in sitea exhibited no evidence of bioaccumulation of this cation,the needles from plants in site b illustrated a threefoldincrease in concentration as compared with the soil.

In the case of tin, there was little evidence of clearlydefined biomagnification with the exception of the needlesof pines collected from site b.

The gold concentration of the soil varied between the twosites (Table 1); in site a, with the higher gold soil concentra-tion, bioaccumulation was evident particularly in theneedles of the Corsican pines. However, in the case ofmaterial collected from site b, bioaccumulation was con-fined to the stems. Bioaccumulation of this valuable cationhas also been reported elsewhere: Rashed (1995) in a studynear the shores of the High Dam Lake and the adjacentdesert at Aswan (Egypt) observed that Glinus lotoides con-tained enhanced concentrations of Au, Ag, Co, Cu, Ni, Pb,Fe, and Sr.

Thus, in the case of material collected from the con-taminated site b, bioaccumulation of Mn, Co, Ni, Cu, Zn,Ag, and Sn was evident in needles and bioaccumulation ofCu, Zn, and Au in stems. However, Herr et al. (1996), in theirstudy of vegetation around disused copper and sulfur minesin southeastern Ireland, found that none of the analyzedvegetation has enhanced zinc (cadmium), iron, or copperconcentrations.

Hence, it may be considered that plants of Corsican pinegrowing in a metalliferous area of Cyprus provide, by theirability to bioaccumulate metals, an effective mechanism tomonitor environmental quality. Dmuchowski and By-tnerowicz (1995) mapped environmental pollution in Po-land by the chemical analysis of the needles of Pinussylvestris; they noted that enhanced zinc, cadmium, lead,and arsenic pollution could limit the growth of some sensi-tive species. Kozlov et al. (1995) determined concentrationsof metals in birch leaves around the Severonikel smelter innorthwestern Russia and found, as also indicated in thisinvestigation, that the concentrations of nickel and copperwere enhanced. In the current investigation, the needles arethe more effective of the two types of tissues analyzed which

is interesting as the needles are in place on the trees for onlya finite period. This marked bioaccumulation by the needlesis in agreement with the findings of Dinelli and Lombini(1996), who, working with Silene armeria and the trees Salixspp. and Populus nigra, found enhanced metal concentra-tions in the leaves. The route of such cations to the plants ofCorsican pine will include transport following the atmo-spheric erosion of metalliferous areas and uptake via therooting systems of the plants. In the latter case, the transferof the elements to the leaves and their subsequent bioac-cumulation there are interesting.

CONCLUSIONS

The ranking of elements in the stems and needles ofCorsican pines differed in samples obtained from controland metal-contaminated sites in the Mount Olympus areaof Cyprus. These plants were found to act as effective bioac-cumulators of heavy metals. In the contaminated site, Mn,Co, Ni, Cu, Zn, Ag, and Sn were bioaccumulated by theneedles, while Au was bioaccumulated by the stems; Cu andZn were bioaccumulated by both stems and needles of theCorsican pines and the tissue copper values were markedlyenhanced in material collected from the contaminated sitewhere a 20-fold increase occurred in the stem samples anda 180-fold increase in the samples of the needles. It is henceapparent that plants of Corsican pines can serve as aneffective biomonitor of environmental quality in areas sub-jected to metalliferous pollution.

ACKNOWLEDGMENT

The author thanks Mr. D. Lacy for technical assistance.

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