extractable organic matter in municipal wastewaters. 2. hydrocarbons: molecular characterization

Extractable Organic Matter in Municipal Wastewaters. 2. Hydrocarbons: Molecular Characterizationt

Robert P. Eganhouse* and Isaac R. Kaplan

Department of Earth and Space Sciences and Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California 90024

Hydrocarbons isolated from southern California municipal wastewaters were analyzed by high-resolution gas chromatography and computer-assisted gas chromatography-mass spectrometry. Most of the hydrocarbons (56-77%) are not chromatographically resolvable and probably derive from petroleum products such as lubricating oils. Normal, iso-, and acyclic isoprenoid alkanes along with alkylcyclohexanes and numerous series of substituted benzenes and polycyclic aromatic hydrocarbons compose the major fraction of the resolvable hydrocarbons. Polycyclic terpenoids occur as trace constituents and appear also to be of ancient, not recent biosynthetic, origin. However, the virtual absence of 17a(H),lsa(H),2lp(H)- 28,30-dinorhopane, a specific marker of California oils, indicates that locally produced petroleum is, a t most, a minor contributor to these wastewaters. A homologous series of long-chain alkylbenzenes presumably derived from the LAS-type detergents was identified. These compounds seem to be abundant and ubiquitous domestic wastewater constituents that might be exploited as anthropogenic waste tracers in the marine environment.

Introduction Municipal wastes are widely recognized as an important

source of petroleum hydrocarbons to the ocean (1-4). More specifically, a number of recent studies have im- plicated local sewage discharges as the cause of hydrocarbon pollution in both river and marine waters and sediments (4-10). Often the connection between source and sedimentary sink has been established by gas chromatography (GC) alone or by GC in conjunction with an- cillary fingerprinting techniques such as infrared and UV-visible absorption and fluorescence spectroscopy.

Even though these techniques can provide a means of correlation for a complex organic mixture such as petroleum, they are generally incapable of elucidating detailed structural information without considerable effort. Com- puter-assisted gas chromatography-mass spectrometry (GC-MS), on the other hand, has been successfully used to verify precise structures of individual sewage tracers such as coprostanol (11, 12). Furthermore, computer manipulation of spectral data (e.g., mass fragmentography), allows rapid examination and tentative identification of important series of marker compounds, typically present only at trace levels (13, 14).

+Publication No. 2218, Institute of Geophysics and Planetary Physics, University of California at Los Angeles.

Several studies in recent years have, in fact, used GC- MS in the examination of municipal wastewaters (10, 15-19). However, most of them have focused either on the major components of the total extractable organic matter, most of which are polar nonhydrocarbons (20,21), or on specific environmentally significant compounds such as the chlorinated hydrocarbons. A notable exception is the recent study made by Barrick (10) in the Seattle-Puget Sound area. This report differs from those previous in that it presents an extensive and detailed molecular inventory of the hydrocarbon compositions of five effluents from southern California. Because of the multiple inputs of petroleum to the ocean in this region (5, 22), we were mainly interested in establishing a comprehensive de- scription of wastewater hydrocarbons for later use in organic source differentiation in marine sediments. There- fore, a large number of samples were analyzed to monitor both temporal and plant-to-plant variability. One highly important aspect of this study was to identify compounds that originate from sewage. These will be essential in future studies of the environmental distribution and fate of wastewater organics.

Experimental Section Sampling and Extraction. Samples of final effluent

were collected from the four major treatment plants in southern California according to methods outlined earlier (2,20); locations of these plants and general characteristics of their effluents are described therein.

For a brief summarization, duplicate 3-L 24-h composite samples of final effluent were obtained at various intervals during 1979. One of the two samples was immediately preserved at pH 1 (HC1) with hexane and refrigerated at 10 OC; the other was filtered with a Whatman GF/A filter, and 2 L of the filtrate was preserved and stored in the same fashion. All samples were extracted with chloroform (CHCl,). The combined hexane/CHCl, extracts were concentrated, dehydrated, treated for sulfur removal, and esterified (BF,-MeOH).

Separation of the esterified extracts into general compound classes was achieved by chromatography on silica gel coated thin-layer plates (CH2C12). Five bands including the total hydrocarbons (THC) were removed and eluted with appropriate solvents. Following high-resolution GC analysis, selected THC fractions were rechromatographed by pentane elution and separated into two or more subfractions. In most cases only two subfractions were isolated: (1) total aliphatics (Al, R, 0.92-1.0); (2) total aro-

0013-936X/82/0916-0541$01.25/0 0 1982 Amerlcan Chemical Society Environ. Sci. Technol., Vol. 16, No. 9, 1982 541

matics (Ar, Rf 0-0.92). One sample (Hyp-7 mi, October 15,1979) was separated into three subfractions: (1) Al (Rf 0.92-1.0); (2) Arl (R, 0.86-0.92); (3) Ar2 (Ef 0.05-0.86). The A1 subfraction contained normal, branched, and cyclic hydrocarbons, whereas the Arl and Ar2 subfractions were isolated on the basis of their UV fluorescence/absorption and chromatographic properties. For example, the Arl band absorbs UV strongly and contains many of the alkyl-substituted benzenes in addition to a portion of the >C20 cyclics. The Ar2 subfraction includes a broad fluorescent band (Rf 0.05-0.35) corresponding to the polycyclic aromatic hydrocarbons (PAH).

Gas Chromatography. Following gravimetric analysis (cf. ref 2,2O), the hydrocarbons were chromatographed on high-resolution glass capillary columns (SE-54,15 m X 0.25 mm) with Carlo Erba FTV 2150 and 2350 instruments equipped with flame ionization detectors and "Grab"-type split/splitless injectors (23). The analyses were performed by splitless injection of hexane solutions according to the following protocol: 40-260 "Cis,, a t 4 "C/min, injector/ detector temperature 275 "C, linear carrier (He) velocity 30 cm/s. Hydrocarbon concentrations reported here were cbmputed by using response factors determined from an n-alkane standard that was run the same day (20). In order to test the efficiency of hydrocarbon recovery, known amounts of two standards, triisopropylbenzene (RS,) and deuterated tetracosane (RS,), were added to each effluent sample prior to preservation. On the basis of the gas chromatographic analyses, recoveries of these compounds were 59 f 7% and 64 f 8%, respectively. No attempt has been made to correct the hydrocarbon concentrations reported here for recovery.

Selected THC fractions submitted to GC-MS analysis and subsequently separated into A1 and Ar subfractions were also analyzed by GC using a Hewlett-Packard 5830A instrument equipped with a split/splitless injector and flame ionization detector. In these cases, a fused silica capillary column (SE-54,30 m X 0.25 mm) was employed under conditions similar to those described above except that the column upper temperature limit was 275 "C.

Gas Chromatography-Mass Spectrometry. GC-MS analysis of selected representative hydrocarbon fractions was performed on a Finnigan 4000 quadrupole mass spectrometer interfaced with a Finnigan 9610 gas chro- matograph. Chromatographic separation was achieved with a fused silica capillary column (30 m X 0.25 mm, J & W; wall coated with SE-54) under the following conditions: injector temperature, 275 "C; column temperature, 35-280 OC at 4 "C/min; linear carrier (He) velocity, 30 cm/s. Mass spectrometric conditions were as follows: ion-source temperature, 240 OC; electron-beam energy, 70 eV. Electron impact mass spectral data were acquired and processed with a Finnigan INCOS 2300 data system.

The identifications presented here are based upon one or combinations of the following: (1) comparison of sample spectra with those of authentic reference compounds, computer library spectra and/or published spectra; (2) coinjection with authentic standards; (3) gas chromatographic retention times (SE-54). As used here, the term "mass fragmentography" refers to the computer-assisted extraction and display of a specific ion from the total ion current.

Results and Discussion General Characteristics. General features of the

wastewater hydrocarbons are given in Table I, and an inventory of prominent constituents identified by GC/MS is provided in Table 11. Representative gas chromatograms of the total hydrocarbon fractions for each effluent

542 Environ. Sci. Technoi., Vol. 16, No. 9, 1982

can be found in Figure 1; for reference, Figure 2 provides greater detail on individual aliphatic and aromatic components of the Hyperion 7-mile (Hyp-7 mi) effluent.

Based upon our analyses, the outstanding characteristic of the hydrocarbons in southern California's wastewaters is the consistency in their composition. Although a few specific compounds (e.g., benzothiophenes) were found in only one or several of the effluents, the vast majority of the identifiable constituents were common to all. Varia- tions between effluents and with time for any one effluent appear only in the relative abundances of the major compound groups. Even in the case of specific trace constituents such as the pentacyclic triterpanes, mass fragmentography reveals nearly identical distributions for all of the effluents (Figure 3). A most striking example of this compositional uniformity is the JWPCP effluent (Joint Water Pollution Control Plant, Los Angeles County; cf. ref 2), which was sampled 24 times during 1979. Gas chromatograms of the total hydrocarbons from these samples are virtually superimposable.

In agreement with recent work (9,10,15) the predominant resolvable hydrocarbons are the normal alkanes. Total n-alkanes recovered from unfiltered samples range from 0.066 to 6.29 mg/L, and their concentrations are linearly correlated with that of the total hydrocarbons (r = 0.97, Table I). By comparison, Seattle's Metro waste effluent contains approximately 0.05-0.15 mg of n-alkanes/L (particulates only; ref IO). The variation in total n-alkane contents we observed for unfiltered samples probably results from both the influent nature and, more importantly, the waste treatments involved. For example, the high values found for the Hyp-7 mi samples reflect the fact that this effluent is a slightly diluted sludge. The other wastewaters sampled are either primary effluents or a combination of primary plus secondary effluents and, with respect to total solids and extractable organics, are much more dilute (2).

Whether filtered or not, all effluents we examined had roughly equivalent proportions of total aliphatic and aromatic hydrocarbons (2); however, filtered samples typically showed an enhancement in the relative concentrations of the lower and medium molecular weight aromatics (viz., alkylbenzenes, naphthalene, and biphenyl plus alkyl homologues). This may reflect some fractionation of the aromatics on the basis of water solubility (24).

Planimetric measurements of the gas chromatograms showed the majority (5677%) of wastewater hydrocarbons to exist as nonresolvable branched, cyclic, and aromatic constituents (cf. Table I and ref 3,9,1O) which appear as broad unimodal and bimodal humps (i.e., unresolved complex mixtures (UCM); cf. Figures 1 and 2). Such humps are frequently encountered in petroleum-polluted sediments (4, 7, 9, 25, 26) and are often attributed to weathered and/or microbially degraded petroleum residues. However, they are also characteristic of refined products such as lubricating and fuel oils (3,6, 7,27) and may occur as the microbial decomposition and resynthesis products of biogenic materials (28).

For most samples examined here, the UCM was unimodal, centered in the range 1800-2300 (Kovats Index) and extended from 1000 to 3200; bimodal distributions centered at 2100-2200 and 2600-2700 were also observed. Qualitatively, the appearance of the UCM is quite similar to that reported in the Seattle study (IO). Whereas the presence of the UCM in these samples is strongly sug- gestive of a petroleum origin, the variable nature of the distributions is most likely to changing input of assorted degraded and refined petroleum residues and wastes. Van

Table I. General Characteristics of Total Hydrocarbon Fractions in Southern California Municipal Wastewaters, 1979

effluenta

JWPCP

Hyp-5 mi

Hyp-7 mi

OCSD

CSD

JWPCP

Hyp 5 mi

Hyp-I mi

OCSD

CSD

sampling date

1/15/79 2/15/79 3/14/79 4/4/79 5/15/79 6/15/79 7/16/79 8/15/79 9/13/79 101 1517 9 11 11 5 17 9d 12/13/79 1/15/79 4/18/79 7/16/79 10/16/79 1/15/79 4/18/79 7/16/79 10/15/79 1/15/79 4/12/79 7/16/79 10/16/79 1/16/79 4/17/79 1/11/79 10/16/79

1/15/79 2/15/79 3/14/79 4/4/79 5/15/79 6/15/79 7/16/79 811 5/79 9/13/79 10/15/79 111 15/79d 121 1317 9d 1/15/79 4/18/19 7/16/79 101 16/79 1/15/79 4/18/79 1/16/79 101 15/79 1/15/79 4/12/19 7/16/79 10/16/19d 1/16/79 4/17/79 7/17/79 10/16/79

THC, mg/L

10.6 14.2 14.3 16.6 13.0 15.6 15.9 20.9 18.2 16.1

14.0 5.1 6.9 5.7 6.5

397 314 297 297

5.7 10.9

7.0 7.8

11.8 8.2

10.4 18.7

2.18 1.78 2.36 1.53 1.29 2.13 2.18 3.29 1.61 2.19

1.92 3.04 2.90 3.10

17.6 13.2

9.42 7.08 1.23 1.63 1.73

1.22 1.78 2.21 2.66

c n-alkanes, max mean %res /.lg/L UCM maxb n-alkane OEPC HC's, % Pr/n-C,, Unfiltered Samples 405 1930 573 2100/2660 7 04 2120/2680 174 2130 592 2100/2700 679 220512700 580 213512730

1180 2285 719 214012625 49 1 2200

532 2175 113 1820

96 1890 66 1995

105 1980 6290 1890 5090 1870 3500 1960 4490 1950

97 1865 125 1860

98 1945 108 1910 781 17 7 512660 271 2285 305 1675

1710 1640 Filtered Samples 98.3 2160 50.5 2215

108 2255 60.1 2170 48.7 2255 78.9 2200 66.6 2280

155 2180 52.1 2175 55.2 1870

34.6 1850 47.2 1790 51.3 2035 43.9 2020

263 1860 203 1840 128 1930

97.4 1900 32.2 2230 25.0 1985 33.0 1895

85.7 1670 99.5 2130

108 2310/1530 253 1690

1.01 1.05 1.08 1.05 1.04 1.05 1.02 1.08 1.05 1.05

1.08 1.10 1.07 1.00 1.10 1.14 1.17 1.16 1.17 1.14 1.08 1.12 1.11 1.11 1.08 1.07 1.07

0.99 1.04 1.02 1.01 1.00 1.00 1.04 1.08 1.02 1.10

1.02 1.04 1.00 1.01 1.16 1.17 1.14 1.14 1.09 1.04 0.96

1.02 1.07 1.01 0.87

39.5

45.5

32.5

31.1

34.1 27.9 24.5 30.7 36.8 30.9 26.2 29.3 43.0 30.4 38.6 31.1 39.6 37.5 51.9 36.9

30.2

35.4

23.3

31.6

22.5 32.1 22.9 26.7 36.0 33.7 27.9 35.9 30.8 25.4 44.3

44.2 43.0 31.7 44.2

0.51 0.54 0.48 0.51 0.48 0.38 0.46 0.43 0.46 0.43

0.48 0.62 0.55 0.53 0.59 0.53 0.52 0.53 0.51 0.55 0.71 0.55 0.15 0.57 0.49 0.49 0.47

0.51 0 37 0.43 0.44 0.37 0.32 0 44 0.40 0.38 0.46

0.56 0.54 0.62 0.60 0.58 0.53 0.53 0.50 0.47 0.53 0.57

0.59 0.52 0.45 0.53

a JWPCP (Joint Water Pollution Control Plant, Los Angeles County), Hyp-5 mi (City of Los Angeles, 5-mile outfall), Hyp- Maxima

Mean OEP is the average of all running OEP values calculated for n-C,, to n-C,.

7 mi (City of Los Angeles, 7-mile outfall), OCSD (Orange County Sanitation District), CSD (City of San Diego). of the unresolved complex mixture given in Kovats indices; if bimodal, numerator refers to index of the dominant mode.

Sample lost,

Vleet and Quinn (9) found that 85% of the hydrocarbons in Providence, RI, effluents were contained in the UCM. However, their analyses were performed on (packed) columns of lower resolution than those used in this study. Thus, comparison of their results with ours is difficult.

In the past, the pristane/n-C1, ratio has been used to indicate the degree of microbial degradation because n- alkanes are metabolized more readily than branched species (15). The consistent ratios we observed, particularly in the case of the Hyp-5 mi and Hyp-7 mi effluents

(Table I), which represent the resultant products of different treatments to essentially the same influent, suggest but do not prove that waste treatment (e.g., anaerobic digestion) probably has little effect on the catabolism of hydrocarbons. This same conclusion was reached by Giger et al. (15), who examined primary and secondary wastewater effluents. In contrast, undisturbed surface sedimenb (0-1 cm) in the immediate vicinity of the JWPCP outfalls (29) as well as surface sediments in deeper portions of the adjacent San Pedro Basin (5,29) contain almost no normal

Envlron. Scl. Technol., Vol. 16, No. 9, 1982 543

Table 11. Selected Compounds Identified in Wastewater Effluents from Southern Californiau

peak no.

d

3 8

11 14 16 19

5 9

12 14 17 22 25 30

2 6

10 13 1 5 18 20 21 23 24 28 31 32 33

1 4 7

26 64 67 34 36

88 89,65 90,66 9 1 92 93,35 94

69 37 38 72 73 74 70 7 1 68

75 39 40 41 42 43 44 45 46

concn compound range,b pg/L means of identificationC

Alkanes n-alkanes, C,,-C,, 70-6300 SM, C, RT, STD isoal kanes 4-450 SM, RT

2-me thylundecane 2-me thyldodecane 2-methyltridecane 2-methyl te tradecane 2-methylpentadecane 2-methylhexadecane

acyclic isoprenoids: 2,6-dimethylundecane 2,6,1O-trimethylundecane 2,6,10-trimethyldodecane 2,6,10-trimethyltridecane 2,6,10-trimethylpentadecane 2,6,10,14-tetramethylheptadecane 2,6,10,14-tetramethylnonadecane

unknown branched C,,:,

n-alkylcyclohexanes pentylcyclohexane hexylcyclohexane hep tylcyclohexane oc tylcycl ohexane nonylcy clohexane decylcyclohexane undecylcyclohexane dodecylcy clohexane tridecylcyclohexane tetradecylcyclohexane pentadecylcyclohexane hexadecylcy clohexane hep tadecylcy cldhexane octadecylcyclohexane

Cyclics

7-650 SM, RT

4-450 SM, RT

alkyldecahydronaphthalenes 0.5-50 SM C, Decalins C, Decalins C, Decalins

5a -pregnane 5a-homopregnane Sa-cholestane (11) 13p,l7a-diacholestane (20R,S; I) 24-ethyl-l3p,17a -diacholestane ( 20R,S ; I)

C,, diterpane C,, diterpane C, diterpane C,, diterpane C, diterpanes (R ,S ) C,, diterpanes ( R , S ) C,, diterpanes (R ,S )

steranes <0.5-50 SM, RT

tricyclic diterpanes (V) <0.5-50 SM, RT

pentacyclic triterpanes 17a(H)-22,29,30-trinorhopane (VI) 17a(H),2l~(H)-30-norhopane (VI) 17a(H),21p( H)-hopane (VI) 1 7 4 H),21p( H)-homohopanes (R,S; VII) 17a(H),21~(H)-dihomohopanes (R ,S ; VII) 1701 (H), 2 l p (H)- trihomohopanes (R,S; VII) 17p( H) 2 l a ( H)-30-normoretane (IX) 17p(H),2la(H)-moretane (IX) 18a(H).22,29,30-trinorhopane (VIII)

Aromatics alkylbenzenes.

C, benzenes 5-phenyldecane (XI) 4-phenyldecane (XI) 3-phenyldecane (XI) 2-phenyldecane (XI) 6-phenylundecane (XI) 5 phenylundecane (XI) 4-phenylundecane (XI) 3-phenylundecane (XI)

< 0.5-50 SM, RT

25-2200 SM

544 Envlron. Scl. Technol., Vol. 16, No. 9, 1982

Table I1 (Continued)

peak no. 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63

76 77 78 79 81 82 80 84 86 87

compound 2-phenylundecane (XI) 6-phenyldodecane (XI) 5-phenyldodecane (XI) 4-phenyldodecane (XI) 3-phenyldodecane (XI) 2-phenyldodecane (XI) 7-phenyltridecane, 6-phenyltridecane (XI) 5-phenyltridecane (XI) 4-phenyltridecane (XI) 3-phenyltridecane (XI) 2-phenyltridecane (XI) 7-phenyltetradecane (XI) 6-phenyltetradecane (XI) 5-phenyltetradecane (XI) 4-phenyltetradecane (XI) 3-phenyltetradecane (XI) 2-phenyltetradecane (XI)

naphthalene 2-methylnaph thalene 1 -methylnaphthalene C, naphthalenes C, naphthalenes C, naphthalenes biphenyl phenanthrene C phenanthrenes fluoran thene

polycyclic aromatics :

he teroatomics: 83 dibenzothiophene 85 C, dibenzothiophenes

concn means of range,b kg/L identificationC

13-1250 SM, RT, STD

<0.5-50 SM, RT, STD

a Major components and significant constituents only are listed, Peak numbers refer to those shown in Figures 1-3. RO- man numerals refer to structures shown in Figure 5. Range of concentrations refers to entire compound class in unfiltered samples. with published and/or computer spectral matching, C, peak coincidence after coinjection with authentic standards; RT, comparison with retention data; STD, comparison of the unknown spectrum t o the mass spectrum of authentic reference material.

Compound identifications based on one or more criteria as follows: SM, comparisons of sample mass spectra

Peaks of n-alkanes designated as C, in Figures 1 and 2.

and branched alkanes. Thus, exposure of wastewater hydrocarbons in the marine environment leads to rapid breakdown of the simple alkanes prior to and during sedimentation.

Alkanes. Normal alkanes ranging from Clo to CS were found as the major hydrocarbons in all samples. For both unfiltered and filtered wastewaters, the dominant homologues were in the range C14+7 (cf. ref 10). As evidenced by values of mean odd-even predominance (OEP; ref 30) only slightly greater than unity, the majority of the n-alkanes are probably of petroleum or microbial origin (28, 31). Microbial hydrocarbons may derive from direct biosynthesis or as the result of the alteration of exogenous lipids (e.g., decarboxylation of fatty acids). Odd carbon compound preference occurs a t high molecular weight (>C,; cf. Figure 21, indicating that plant epicuticular waxes are present (32). In general the n-alkane distributions were similar for all of the effluents (Figure 4); however, the Hyp-7 mi samples showed a greater relative abundance of plant-wax hydrocarbons. This is explainable by the se- lective incorporation of large plant detritus into sludge during primary screening and settling. Macroscopic evi- dence of such remains (e.g., seeds, stems, and leaf parts) was obvious.

A suite of isoalkanes (Clo-CB, C16 maximum) and acyclic isoprenoids (c13-c23, C19 maximum) excluding C17,C22 homologues were also abundant (Figure 2, Table 11); however, no anteisoalkanes were identified. The presence of these homologies can be attributed to input of petroleum products, not recent biosynthesis (33,34), and the similarity in the distributions may signal a common source of

these compounds to the four treatment plants. Cyclics. The most abundant cyclic compounds were

the n-alkylcyclohexanes (monitored with m/z 82,83) that extend from C6-Cz2-substituted species (Figure 2, Table 11) and are probably of fossil origin (35). Trace quantities of alkyl-substituted methylcyclohexanes (C,-C,) were also found in most samples.

A group of bicyclic compounds (viz., alkyl-substituted decahydronaphthalenes) were present in those extracts examined by GC-MS (Figure 2, Table 11). Mass spectra of these compounds (formula CnHZn+ n = 11-13) exhibit a strong molecular ion and intense fragments at m / z = 55, 67, 81, and 95. The parent compound, Decalin, is commonly used as an industrial solvent, but i t was either present in minute quantities or not detected. The alkyl- substituted homologues are almost certainly products of the catalytic hydrocracking of petroleum (36).

Of particular interest regarding their potential for fingerprinting and source differentiation in the marine environment are the cyclic terpenoids. These trace compounds, which include steroids, tricyclic diterpanes, and pentacyclic triterpanes, have proven useful in studies of petroleum formation (37-40) and biodegradation (41), oil-oil and oil-source rock correlations (42-46), and petroleum pollution in the environment (13,25,47). Their use is based upon the fact that, geologically speaking, they are stable compounds, and the number of structural pos- sibilities of biogenic precursor molecules is relatively lim- ited. Upon deposition and during subsequent burial in sediments, they are systematically altered through ther- mocatalytic and microbial processes yielding a mixture of

Environ. Sci. Technol., Vol. 16, No. 9, 1982 545

I loon 15o0 200 250' 2+5~ lsot her mal w

Flgure 1. Gas chromatograms of the total hydrocarbon fractions from southern California wastewater effluents (unfiltered samples): JWPCP, 4/4/79; Hyp4 mi, 1/15/79; Hyp-7 mi, 10/15/79; OCSD, 1/16/79; CSD, 4f 17/79 (dashed line represents baseline).

new, but structurally similar, molecules. Thus, older modified terpenoids can be readily differentiated from those produced by recent biological activity. Distributions of the terpenoids are easily monitored by mass fragmentography using, for example, m/z 217 (regular steranes) and 191 (diterpanes and triterpanes; cf. Figure 3).

The steranes in these samples were complex and owing to their low abundance are identified only by general class. Complete structural assignments were not possible without further sample enrichment. The dominant compounds were the rearranged c27-czg steranes or "diasteranes" (structure I, Figure 5). Several isomers of either the 13/3,17a or the 13a,17@ stereochemistries were present for each carbon number. On the basis of retention data and the intensity of the m/z 232 fragment (41,48), the 13@,17a isomers are tentatively identified as the predominant species. Other important components included CZ1, CZ2, and Cz7-CZs 5a steranes (11) with small amounts of 5/3 isomers (111). Isosteranes (5a,14@,17@ stereochemistry, structure IV), characterized by a strong m/z 218, were also found (CZs, Czg) as were c27-c29 sterenes, although in the

546 Environ. Sci. Technol., Vol. 16, No. 9, 1982

latter case, the position of the double bond could not be determined. The remarkable similarity of the m/z mass fragmentogrm suggests a common origin for the steranes, and the dominance of the diasteranes may indicate that the fossil source of these steroids was biodegraded (41). If so, the normal and isoalkanes must have originated from an altogether different source because they are more subject to removal by microorganisms than are polycyclic hydrocarbons (41).

A series of tricyclic diterpanes from C21-C29 (C23 maximum), sometimes excluding Czz and Cn homologues, were present (Figures 3 and 5; structure V). The lCZs homologues consisted of nearly equal amounts of R and S diasteromeric pairs due presumably to a branch in the alkyl side chain (49). The triterpanes were dominated by the degraded and extended 17a(H)-hopane series (Figure 3) and included 17a(H)-trinorhopane (VI, R = H), 17a- (H),21/3(H)-norbopane (VI, R = CzHB), 17a(H),21@(H)- hopane (VI, R = CH(CH3)2), and the C31-C35 homohopanes (VII) present in roughly equivalent amounts as S and R diasteromers (cf. Figures 2 and 3). 18a(H)-22,29,30-tri-

I ldo" 150° 206 Isothermal e

Flgure 2. Gas chromatograms of the total hydrocarbons and hydrocarbon subfractions of the Hyperion 7-mile effluent (unfiltered, 10115179). Numbers refer to compound indentifications listed in Table 11.

norhopane (VIII) was also found along with C29-C32 moretanes (17P(H),21a(H); IX); however, neither the 17P-(H),21P(H) compounds associated with recent biogenic activity nor any triterpenes were detected.

With the possible exception of the sterenes, which may occur as recent biological products, these distributions indicate an ancient (i.e., petroleum) origin for the cyclic terpenoids. Surprisingly, 17a(H),l8a(H),2l@(H)-28,30- dinorhopane (X) was absent or found in exceedingly small quantities. This compound was recently identified as a major component of the Monterey Shale (50) and of numerous southern California oils and seeps (42). Subse- quently, its presence was verified in southern California marine sediments (5, 49) as well as Los Angeles storm- waters (51) and California aerosols (52). Because this particular triterpane has only rarely been found in other crude oils, its occurrence in environmental samples is taken as an indication of contamination by southern California oils or weathered shale. Conversely, its absence or minimal presence in wastewaters indicates a major input of petroleum from other areas. In other respects, the terpane profiles we observed are very similar to those reported for San Pedro Basin surface sediments (5) and water column particulates collected in the San Pedro and Santa Monica Basins (53). This is not surprising as these basins serve as receiving areas for the wastewater effluents of the Hy- perion and JWPCP plants (2).

Cycloaromatics. The major identifiable member of this compound class was a series having the general formula CnH2n-8 (n = 9-13). The parent molecules of the assem- blage consisted of indan, tetrahydronaphthalene (Tetralin),

and possibly C,,.-substituted benzenes. Indan and Tetralin have been reported in primary and secondary effluents previously by Giger et al. (15). The higher alkyl-substituted homologues of these compounds could not be pos- itively differentiated on the basis of mass spectral data alone. However, the complex distributions observed by molecular ion mass fragmentography were very similar for all effluents, indicating a common source. It seems most likely that hydrocracking of petroleum is responsible for their presence in wastewaters. Whether this occurred naturally during the diagenetic alteration of organic matter or through industrial cracking is unclear. Because of their moderately stable cycloaromatic structure and ubiquitous presence in southern California municipal wastewaters, these molecules may be useful tracers for sewage hydrocarbons in coastal marine sediments, a t least in this area. This assumes they are not significant constituents of other source materials.

Aromatics. Heteroatomics. The aromatic hydrocarbons in wastewaters comprise a rather complex mixture of compounds as illustrated in Figure 2. Alkyl-substituted benzenes were abundant in all samples and formed two distinct groups : (1) C1-Ce-substituted benzenes; (2) Clo-CI4-substituted benzenes. The former consist of numerous isomeric assemblages that are commonly found in wastes (15, 16, 18). The latter occur strictly as (1- alky1,alkylJbenzenes with side chains ranging from Clo to C14 (structure XI; Figure 5) . Alkylbenzenes in this molecular weight range have been detected before in sewage extracts (17,18); however, their exact structure and possible origins were not reported. In these samples, the

Environ. Scl. Technol., Vol. 16, No. 9, 1982 547

Ditcrpanes , ,

WPCP

I

74 h j ,

Time- Figure 3. Mass fragmentograms ( m / r 191) for cyclic terpenoids in wastewater effluents showing major diterpane and trlterpane homologies. Numbers refer to compound identifications listed in Table 11.

distributions of structural isomers a t a given molecular weight were invariant, but the abundance of individual molecular weight groups fluctuated from sample to sample. At least two suggestions can be offered as to their origin: either (1) they are unreacted residues of the industrial synthesis of linear alkylbenzenesulfonate (LAS) detergents (i.e., alkylbenzenes prior to sulfonation); or (2) they are desulfonated LAS (54). In any event, the highly specific

and restricted isomer distributions found in these samples strongly indicate a synthetic origin (e.g., alkylation of benzene with long-chain alkenes). Detection by mass fragmentography (mlz M+, 91, 105) is enhanced by the absence of interfering background signals in this chromatographic region and by the intensity of the fragments formed by facile cleavage at the branch point in the side chain (Figure 6). Consequently, further purification be- yond isolation of the total hydrocarbons is usually un- necessary. Despite their reputed biodegradability, these compounds apparently emerge from wastewater treatment as major components (cf. Table 11).

Recently, Clo-C13-substituted benzenes of the same structures were reportedly observed in particulates trapped in the San Pedro Basin near the JWPCP outfall system (53). Thus, it seems the LAS residues may also survive aerobic attack in the water column and ultimately become deposited in nearby sediments. If they can be preserved in outfall-affected sediments (which are sometimes anaerobic due to high organic loading), these compounds may serve as model tracers for studies of sewage dispersal and degradation.

A number of polycyclic aromatic hydrocarbons (PAH) were also found as prominent wastewater constituents (Figure 2, fraction Ar2). The major components, in order of abundance, were naphthalene plus Cl-C5 homologues, phenanthrene plus C1-CI homologues, and biphenyl plus C1-C3 homologues. Species present only in minute quantities included fluorene plus C1-C3, fluoranthene plus C1 and C2, anthracene, pyrene plus C1 and C2, acenaphthene, 2,3-benzofluroene, benz[a]anthracene, chrysene/tri- phenylene plus C1-C3, benzo[i]fluoranthene, benzo[e]- pyrene, benzo[a]pyrene, 9,10-diphenylanthracene, 1,2,5,6-dibenzanthracene, benzo[g,h,l]perylene, and an- thanthrene.

Alkyl homologue distribution plots for the dominant species (i.e., naphthalene and phenanthrenelanthracene homologies) based on the integrated currents of the parent ions were quite typical for all effluents (cf. Figure 7), suggesting a common or similar source for these compounds. In general, the abundance of alkyl-substituted homologues, particularly the C2 species, greatly exceeded that of the corresponding parent compounds. This pattern is commonly found for ancient sediments, fossil fuels, and polluted recent sediments (55,56). The input of significant

Unfiltered

u a Filtered

Carbon Number Figure 4. Distribution of normal alkanes in unfiltered and flltered samples of southern California wastewater effluents, 1979.


II.5a steranes III 58 steranes & & & I Rearranged steranes

IV 'h'steranes V: Tricyclic diterpanes VI 17a(H),2ls(H! hopanes

4

R = H,CH,,C,H, R= H,CH, ,C,H, R=H,CH,,C,H,

R

R=H,CH,,C,H, R=1-I,CH3-rClOH,,

13

J

YII. Extended 17a(H), Zls(H)- VIII. 18a(H)-22,29,30- trisnor- IX. 17~(H),21a(H) 'moretanei hopane

C8Hi7

X. 17~(M),18dH),21s(H)-28,30-bisnor- XI. Long chain alkyl benzenes hopane

e,,,, &R*

R, + R, = C9H20- C,,H,B

Figure 5. Structures of various identified wastewater components. Stars indicate asymmetric carbons that give rise to diasteromers.

12 m/z 11 e - ,I 105 f I

RQC

Figure 6. Mass fragmentograms ( m I r 91, 105) used to monitor long-chaln alkyl benzenes along w K reconstructed gas chromatogram (ROC) (JWPCP unfiltered, 4/4/79).

amounts of PAH derived from natural or anthropogenic combustion of organic matter a t high temperature is not indicated here because the nonalkylated parent compounds and (to an increasingly lesser extent) lower alkyl-substituted homologues should be favored in such a case. Moreover, southern California's storm runoff and waste systems are effectively decoupled, unlike those in other areas (9,lO). Thus, mixing in waste streams of industrial/ domestic effluents and materials derived by atmos- pheric deposition on pavement surfaces or erosion of tire

and asphalt is largely prevented. In concert, these facts point to petroleum and its products aa the major source of wastewater PAH in southern California. In the case of the OCSD effluent shown in Figure 7, an additional, perhaps industrial synthetic, source of naphthalene may be responsible for the alteration of the homologue distribution. Other OCSD samples analyzed by GC exhibited the pattern more typically seen (viz. maxima for the C2- substituted homologue).

Two groups of heteroatomics eluted with the total hydrocarbons and were present in measurable quantities: (1) benzothiophenes plus C1-Co homologues; (2) dibenzothiophenes plus C1-C4 homologues. The benzothiophenes were present in JWPCP and OCSD effluents in trace amounts, whereas dibenzothiophenes were relatively abundant in all effluents (Figure 2). These compounds, which are easily monitored by molecular ion mass fragmentography (m/z 184 + 14n, n = &4), were also recently found by Bates and Carpenter (57) in extracts of Seattle's Metro Wastewater effluent. On the basis of their complex homologies with dominant alkyl-substituted species (Fig- ure 7), they are most likely derived from petroleum products (58, 59).

Conclusions The origin of southern California's wastewater hydro-

carbons is undoubtedly related to the usage, production and refining of petroleum. At most, the biosynthetic sig- nature of the higher plant wax hydrocarbons represents

Environ. Scl. Technol., Vol. 16, No. 9, 1982 549

I

C 0 .- c z 4- c e, 0 C 0 0 e, > 0 .- c - B

0 JWPCP - Hyp-5mi -- Hyp-7mi OCSD CSD . . . . , . . . .

I I I I I I I I I I I I I I I L

Number of Alkyl Carbons 0 1 2 3 4 5 0 1 2 3 4 0 1 2 3 4

Flgure 7. Alkyl homologue distributions of C, H2n-12 (naphthalenes), CnH2,-,* (phenanthrenes and anthracenes), and C, H2n-,BS (dibenzothiophenes) in municipal wastewaters from southern California, 1979. Integrated currents are normalized to that of the parent compounds (not corrected for relative response).

a trace contribution. In view of the virtual absence of 17a(H),l8a(H),2lp(H)-28,30-dinorhopane, a specific marker of California oils, most of the petroleum must be derived from non-local sources. The remarkably consistent composition of five effluents which were sampled over a 12-month period indicates that the sources of petroleum being introduced into the waste treatment systems of this region are very similar. Whether these compositions are also typical of effluents from other areas of the world is not fully known at this time. The identification of the alkylbenzene residues of LAS detergents and substituted indans and tetralins in these and other municipal wastewater samples (17,18) may be particularly significant because it offers the possibility of tracing wastewater hydrocarbons into the environment. Future work should be aimed a t determining the preservation potential of the LAS residues and other naturally-occurring tracers such as coprostanol in marine waters and sediments. When taken with known sedimentation rates, such data can be used to estimate the relative input rates of wastewater hydrocarbons to coastal sediments.

Acknowledgments

quisition.

Literature Cited

We would like to thank Ed Ruth for GC-MS data ac-

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Received for review August 31, 1981. Accepted April 6, 1982. Financial assistance from the Department of Energy and Bureau of Land Management (Contract No. EY-76-3-03-0034) is ac- knowledged.

Deposition and Chemistry of Pollutant Metals in Lakes around the Smelters at Sudbury, Ontario

Jerome 0. Nriagu,” Henry K. T. Wong, and Robert D. Coker

National Water Research Institute, Burlington, Ontario L7R 4A6, Canada

Analyses of the suspended particulates in lakes within a 30-km radius of the smelting complex at Sudbury show average Ni, Cu, Zn, and P b concentrations of 1500,420, 540, and 360 pg g-l, respectively. Organic matter consti- tutes 35-60% of the suspended material in the lakes but plays a minor role in the transport of metals to the sediments. The rates of metal accumulation in the sediments have been estimated typically to be 100-600, 50-300, 10-60, and 5-30 mg m-2 year-’ for Ni, Cu, Zn, and Pb, respectively. The enrichment factors for metals in surficial sediments typically are 12-115 for Ni, 10-77 for Cu, 2-10 for Pb, and 2-8 for Zn. These enrichment factors and deposition rates for Ni and Cu are among the highest recorded anywhere in the world. Some of the lakes with pH values of 4.5 or less show no enrichment or accumulation of pollutant metals in their surface sediments, indicating that pollutant metals previously stored in the sediments have since been leached away. This documen- tation that the contaminated sediments can release sub- stantial quantities of toxic metals to the overlying water must have interesting ramifications with regard to the limnological impacts of acid rains.

Introduction Emissions from the mining and smelting activities in

Sudbury, Ontario have engendered extensive biogeochem- ical changes in the surrounding lakes. Numerous studies have focused on the impacts of smelter exhausts on the acidification, metal contamination, and community structure of lakes in the area (e.g., ref 1-11). None of these previous studies has addressed the flux rates for the pollutant metals into the lakes or the transfer of the metals from the surface waters into the sediments. This report deals with the particulate and dissolved trace metals in lakes around Sudbury. The chemical analysis of the suspended material has been linked with studies of the underlying sediments in order to examine the cycling and removal of the pollutant metals in the lake water.

Extensive studies have now documented the fact that lake sediments preserve a good historical record of the natural vs. anthropogenic fluxes of heavy metals into the lake basin (see ref 12-23, for instance). So that the historical record of metal pollution could be deciphered, the

ages and hence the accumulation rates of the recent sediments have been determined by the lead-210 technique. In this report, the changes in the metal profiles of dated sediment cores have then been used to reconstruct the history of anthropogenic metal influx into lakes around Sudbury.

The nickel deposit a t Sudbury was discovered in 1883. The roast yard and smelter were first set up in 1888 at Copper Hill, which could handle 80-100 tons of ore per day, yielding a matte containing 50% of copper and nickel (24). The uncontrolled open-air roasting process released significant quantities of pollutant metals to the air which would have impacted the local lakes; the fumigation of the surrounding areas with the SO2 has destroyed the surrounding vegetation. Metal production in Sudbury grew gradually and reached about 45 000 tons of Ni and 20 000 tons of Cu at the end of the First World War. Sharply increased metal output commenced during the early 1930s and early 1950s (25), and in 1977, the mines at Sudbury produced about 180 000 tons of Ni and 175 000 tons of Cu. The use of roasting beds was discontinued around 1923 when the 510-ft (170 m) stack and sulfur-recovery plant was completed at Copper Cliff. The 1250-ft (381 m) superstack was installed in 1972.

In 1977, the smelters in Sudbury daily emitted about 2.6 tons of Ni, 2.6 tons of Cu, 0.7 tons of Pb, and 6.3 tons of Fe (26); the daily outpouring of 2500 tons of SO2 from the 381-m superstack makes it the single largest point source of this pollutant in the world (26). It has been estimated (27) that about 40% of the Cu and 70% of the Ni emitted are deposited in the immediate vicinity of Sudbury. The area around Sudbury thus represents a unique “laboratory” for studying the long-term impacts of airborne pollutants on aquatic ecosystems.

Methodology The lakes studied are located within a radius of 30 km

from the metallurgical works in Sudbury, Ontario (Figure 1). These Precambrian shield lakes encompags a wide diversity of physical and chemical characteristics and show varying degrees of stress from the acid rains. The geo- logical settings and the general limnology of lakes in the region have been outlined in reports by Conroy et al. (4,

0013-936X/82/0916-0551$01.25/0 0 1982 American Chemical Society Environ. Sci. Technol., Vol. 16, No. 9, 1982 551

extractable organic matter in municipal wastewaters. 2. hydrocarbons: molecular characterization

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