Sources and distribution of hydrocarbons in Bridgwater Bay (Severn Estuary, U.K.) intertidal surface sediments

Estuarine, Coastal and Shelf Science (1988) 21,237-261

Sources and Distribution of Hydrocarbons in Bridgwater Bay (Severn Estuary, U.K.) Intertidal Surface Sediments

Stephen

D. Killops

and Vanessa

J. Howell

Chemistry Department, Royal Holloway Q Bedford New College, London University, Egham Hill, Egham, Surrey, TW20 OEX, U.K. Received 4 June 1987 and in revised form 28 April

Keywords: sediments; intertidal environment; carbons; oil pollution; liquid chromatography; spectroscopy; Bristol Channel

I988

polycyclic aromatic gas chromatography;

hydromass

Hydrocarbon distributions in two intertidal, surface sediments from Bridgwater Bay were examined by high performance liquid chromatography (HPLC), gas chromatography (GC) and gas chromatography/mass spectrometry (GC-MS) to investigate distributions and sources of hydrocarbons. Two major hydrocarbon sources were identified, pyrogenic polycyclic aromatic hydrocarbons (PAHs) and a chronic petrogenic input. Other probable sources were algal, higher-plant and DDT-related pesticides. It was not possible to detect a contribution to the surfacesedimentsfromanearby Liassicshale. Petrogenic biomarkerdistributions were broadly similar in the sediment samples, possibly reflecting a degree of resuspension and mixing of sediments within Bridgwater Bay. However, the significance of some slight differences in steroidal hydrocarbon distributions could not be determined. A relatively greater contribution from the petrogenic source(s) than from the pyrogenic source was noted in the finer grained sediment sample. An extended range of PAHs was noted in both sediment samples, with molecular weights of up to 326 detected. A group of compounds, comprising terphenyls, cyclohexylbiphenyls and dicyclohexylbenzenes, was detected, which appeared to have a petrogenic origin. Introduction Although the Severn Estuary environment has been much studied (Glover, 1984 and references therein), relatively little attention has been paid to the molecular organic constituents of its sediments (Morris, 1984). Biological marker alkanes consistent with petrogenic pollution have been identified in intertidal mud sampled near Aust (ca. 10 miles up-stream from Bristol) (Thompson & Eglinton, 1978; Brassell & Eglinton, 1980). More recent examination of Stert Flats intertidal mud showed that superimposed on the background of petrogenic biomarker compounds was a contribution from a reworked, Lower Liassic ‘paper shale ‘, which outcrops in various parts of the Severn Estuary (Rowland & Maxwell, 1984). The relative proportions of components from each source was found to depend on sample depth, the ‘ paper shale ’ contribution only becoming discernible in deeper samples. In addition, the distribution of background, petrogenic, 0272-7714/88/090237+

12 $03.00/O

@ 1988 Academic Press Limited

238

S. D. Killops Q V..y. Howell

biomarker alkanesin the Stert Flats muds was found to be similar to that noted for Aust muds (Rowland & Maxwell, 1984). Polycyclic aromatic hydrocarbons (PAHs) in Severn Estuary sedimentshave generally been ascribed to the products of fossil-fuel combustion (Thompson & Eglinton, 1978), as they chiefly comprise non-alkylated species. However, alkylated PAHs have been identified from areasaffected by recent coal mining (John et al., 1979; Cooke et al., 1979). While PCB residues have been detected in sediments from the upper part of the Severn Estuary, no significant quantities of polychlorinated naphthalenes or DDT have been reported (Cooke et al., 1979). Bridgwater Bay is an extensive area of muddy, intertidal and subtidal sediments with areasof erosion, stability and deposition. Understanding the movement of sedimentscan be important, asit is likely that someorganic components are absorbed onto clay surfaces and transported as particulate matter rather than as free species in aqueous solution (Readman et al., 1984). Tides and sedimentation in the Severn Estuary have been reviewed recently (Dyer, 1984; Uncles, 1984). As a result of the large tidal currents in the Severn Estuary, it seemslikely that sediment up to sandgrade is mobile most of the time. Differentiation between sediments moving in suspensionor as bedload produces a fairly sharp division between rocky, sandy and muddy areas(Dyer, 1984and references therein; and cf. the sampling sitesin this study). The residual flow of water in the Severn Estuary is generally westerly, and there is probably very little input of material from the Welsh side of the channel. In addition, there appearsto be somecirculatory effect within Bridgwater Bay (Dyer, 1984 and references therein). The present study involved a detailed examination of total neutral extracts, particularly aromatic hydrocarbon fractions, of two intertidal surface sediments and a nearby Lower Liassic ‘paper shale’ in the Bridgwater Bay area of the Severn Estuary, in order to determine hydrocarbon sourcesin the sediments. Contribution of the ‘ paper shale’ to the sediments was sought using several compound classes.In addition, the homogeneity of surface sediments within Bridgwater Bay, resulting from resuspensionand mixing, was investigated by inspection of relative distributions of hydrocarbons in sediments at two sites. Experimental Samples

Samples were collected in April 1984 at three sites in Bridgwater Bay, Somerset, U.K. (Figure 1). A sampleof thinly laminated, organic-rich ‘ paper shale ’ (Lower Liassic) was obtained by excavation of cliff exposure near Kilve village (site a, Figure 1). The outer ca. 10 cm of shale was discarded to minimize the effects of weathering on biomarker distributions. An intertidal mud samplewas collected from Kilve beach, adjacent to the ‘ paper shale ’ sampling site (site b, Figure l), comprising a ca. 10 cm deep pocket of light grey, silty mud overlying bedrock. A second intertidal-mud samplewas taken from Stert Flats (site c, Figure 1) seawardof extensive salt flats, and comprised a ca. l&20 cm section of dark grey, thixotropic mud underlying a thin layer (ca. 10 cm) of sandy sediment (similar to that described by Rowland & Maxwell, 1984). At this site the mud layer was thick and bedrock was not exposed. A schemefor the analysis of these samplesis given in Figure 2. Extraction and isolation of hydrocarbons Mud samplesand pulverized ‘ paper shale ’ (ca. 50 g dry weight) were extracted by ultrasonication (10 min) with a propan-2-al/light petroleum (b.p. 40-60 “C) mixture (4:l v/v,

Sources

and distribution

of estuarine

hydrocarbons

239

'PlS'N

Figure

SEDIMENT AND "PAPER SHALE" SAMPLES

1. Location

of sampling

(ilultrasonication (ii)partifioning

sites in the Bridgwater

%wanoWf.

etiw)

(hexanelwater)

, ~LAL

Bay area of the Severn

Estuary.

TOTAL - ORGANIC EXTRACT

I
(pet. ether/water)

‘r’

EXTRACT

HPLC

INDIVIDUALDOUBLE ALIPHATICS

(ilGC-FID

(OV-1)

(ii)GC-MS-MIDIOV-I) (steranes and terpanesl

(i)GC-FID m-54) (ii)GC-MS-FDC (PAH identification quantification)

(SE-541 and

GC-MS-MID

(SE-54) (monoltriaromatic steroids, methylphenanthrenes and methyldibenzothiaphenes)

Figure 2. Scheme for the analysis of hydrocarbons samples (see Experimental section for details).

(i)GC-FID

IOV-73)

(ii)GC-MS-FiJC IPAH identification1

in sediment

and

‘paper

(SE-S&i

shale ’

240

S. D. Killops

&

V.3. Howell

100 ml). After centrifugation (1500 rpm, 10 min) the supernatant liquid was decanted and partitioned between pre-extracted water and hexane (2:3 v/v, 120 ml), and the organic layer was collected. The extraction was repeated, and the extracts combined to give a total organic extract (TOE). After evaporation to dryness, the TOE was dissolved in a minimum volume of methanol (ca. 1 ml), and hydrolysed by addition of aqueouspotassium hydroxide solution (ca. 0.1 ml, 60 “b w/v) and heating (ca. 40 “C for 24 h). Pre-extracted water (2 ml) was added and the resulting solution extracted with hexane (2 x 1 ml). Organic extracts were combined to yield a total neutral fraction. HPLCfractionation

of total neutralfractions

Conditions of HPLC fractionation have been described elsewhere (Killops, 1986a). Total aliphatic hydrocarbon, total aromatic hydrocarbon and mono/triaromatic steroidal hydrocarbon fractions were isolated (Killops 1986a; Killops & Readman, 1985). Selected aromatic hydrocarbon sub-fractions were also collected, corresponding to the individual fractions ‘ B ’ to ‘ P ’ in Figure 11. GC analysis

offractions

isolated by HPLC

Total aliphatic and total aromatic hydrocarbon fractions were analysed using a Carlo Erba Mega 5360 GC fitted with a flame ionisation detector (FID) and using cooled, ‘oncolumn ’ injection. For total aliphatic fractions a 25 m x 0.32 mm i.d. 0.17 pm WCOTbonded methylsilicone fused silica column (Hewlett-Packard) wasused. For total aromatic fractions a 25 m x 0.32 mm i.d. 0.17 urn WCOT bonded 54:-phenylmethylsilicone, fused silica column (Hewlett-Packard) wasused. Helium carrier gaswas employed (1.2 kg cme2), and all sampleswere injected in hexane solution (0.5 ~1). Selected aromatic hydrocarbon sub-fractions were analysed using a Carlo Erba 4130 GC with FID and splitlessinjection. A 25 m x 0.2 mm id. persilylated Pyrex glass0.2 urn WCOT OV-73 column was used with helium carrier gas (2-2 kg cm-*). Samples were injected in hexane solution (1 ~1). A temperature programme of 1 min at 60 “C, then 60 ’ to 300 “C at 5 ’ rnin~’ was used for all GC-FID analyses. GC-MS analysis of hydrocarbon fractions isolated by HPLC A Carlo Erba 4160 gaschromatograph with cooled, on-column injection wasused with the fused silica capillary column taken directly through to the ion source of a Finnigan 3200 quadrupole massspectrometer (INCOS 2015 data system). Typical MS conditions have been described elsewhere(Killops & Readman, 1985). All sampleswere injected in hexane solution (0.5 pl), and a temperature programme of 1 min at 60 “C, then 60 ’ to 300 “C at 6” min-’ wasused. Aliphatic and aromatic hydrocarbon fractions were analysed using the samefused silica columns employed in the respective GC-FID analysesabove. Sterane and terpane distributions were determined from total aliphatic hydrocarbon fractions using multiple ion detection (MID). Analysis of mono-/tri-aromatic steroidal hydrocarbon fractions also employed MID. Total aromatic hydrocarbon and selected aromatic hydrocarbon sub-fractions were analysed by full data collection (FDC, m/z 50-450).

Results and Discussion Sources of hydrocarbons

in surface sediments from Bridgwater

Bay

The hydrocarbon distributions in the samplestaken appear to be characteristic of these surface sediments (Thompson & Eglinton, 1978; Rowland & Maxwell, 1984). Total

Sources

and distribution

of estuarine

hydrocarbons

241

STERT FLATS

I I

KILVE BEACH SEDIMENT

Ph I

KILVE PAPER SHALE

L tbo’ InJ Figure 3. Gas chromatograms fractionation (numbers denote

200

1

1

300

I-7

isothermal

of aliphatic hydrocarbon fractions rr-alkanes; Pr, pristane; Ph, phytane).

isolated

by HPLC

aliphatic (Figure 3) and total aromatic (Figure 4) fraction gas chromatograms were similar to those observed in other Severn Estuary surface sediments, indicating two major hydrocarbon sources: a biodegraded petrogenic input and a fossil-fuel combustion product (pyrogenic) input (Thompson & Eglinton, 1978). The former was confirmed by characteristic distributions of terpanes (Figure 5), steranes (Figure 6) and aromatic steroidal hydrocarbons (Figure 7) obtained by GC-MS analysis (component identifications are given in Table 1 and Figure 8) (Thompson 8z Eglinton, 1978; Rowland & Maxwell,

242

S. D. Killops

Q

V.J.

Howell

I;

STERT FLATS

MN h

KILVE PAPER SHALE

Figure 4. Gas chromatograms of total aromatic hydrocarbon fractions fractionation (see Table 1 and Figure 8 for component identification).

isolated

by HPLC

1984). Biomarker distributions (Figures 5-7) indicated that the petrogenic components in the sediments were similar to each other, but significantly different from the ‘ paper shale ‘. The latter was considerably less mature, as demonstrated by the predominance of 5a(H), 14a(H), 17a(H), 20R isomers of the C2+& steranes in Figure 6 (e.g. see Mackenzie, 1984). These observations are illustrated by the biomarker ratios given in Table 2. The pyrogenic input was identified by characteristic distributions of non-alkylated PAHs (identified by GC-MS analysis) in the total aromatic gas chromatograms (Figure 4) (Thompson & Eglinton, 1978; LaFlamme 8zHites, 1978), which were very similar to those

Sources and distriburion

of estuarine hydrocarbons

243

STERT FLATS SEDIMENT

KILVE BEACH SEDIMENT

;5IA 3b” 3

KILVE PAPER SHALE

RETENTION TIME

Figure 5. Partial single-ion chromatograms (m/z = 191, MID mode) showing terpane distributions (see Table 1 and Figure 8 for component identification).

recorded for Recent lake sediments in Europe and the U.S.A. (Wakeham et al., 1980b). In addition, similar PAH distributions have been reported in marine and freshwater sediments and in soils (Wakeham et al., 1980band references therein). The ubiquity of this PAH distribution has led to the supposition of a common source-aeolian particulate matter containing adsorbed fossil-fuel combustion products (LaFlamme & Hites, 1978; Wakeham et al., 1980b; Gschwend & Hites, 1981). However, street dust and asphalt have been demonstrated to exhibit similar PAH distributions (Wakeham et al., 1980b), and so urban drainage water may be a significant source of these PAHs in certain environments (Wakeham et al., 1980b; Gschwend & Hites, 1981). The relative importance of these two PAH source/distribution mechanisms to Sevem Estuary sediments requires further examination. While aromatic hydrocarbon distributions for the two sediments were similar to each other, they were markedly different from those of the ‘paper shale’ (Figures 4 and 9). HPLC analysis (Figure 9) suggestedthat PAH aromaticity distributions maximized at ca. nine double-bond equivalents (Killops, 1986a) for both sediments, but for the ‘paper shale’ alkylnaphthalenes (containing five double-bond equivalents) were the dominant

244

S. D. Killops

&

V. .7. Howell

STERT FLATS SEDIMENT

29

KILVE BEACH SEDIMENT

217

224Me

1

KILVE PAPER SHALE

m/z 217

27dia

224Me

Me

RETENTION

TIME

Figure 6. Partial single-ion chromatograms (m/z = 2 17, MID mode) distributions (see Table 1 and Figure 8 for component identification).

showing

sterane

PAHs (Figures 4 and 9). The relatively poor resolution in the HPLC chromatogram (Figure 9) of the ‘ paper shale ’ probably arises from the range of PAH alkylation. Also, methylphenanthrene (MP) and methyldibenzothiophene (MDBT) distributions for the ‘ paper shale ’ were found by GC-MS analysis to be significantly different from those of the sediments (Figure 10). MDBTs were present in lower quantities relative to MPs in the sediments (Table 5), and their distributions were again consistent with a biodegraded crude oil (J. Connan, pers. comm.). Because evidence for a contribution from the ‘ paper shale ’ to the sediments was not found in the data described above, it was sought among aromatic components by a detailed GC-MS-FDC analysis of total aromatic fractions. Major PAHs were approximately quantified in each sample (Table 3) relative to the amount of phenanthrene (chosen because it was readily identified in all samples). Again, however, a contribution to the sediments from the ‘ paper shale ’ could not be detected. Although carbazole, indole, and a compound identified by its mass spectrum as 2-methylthiobenzothiazole [PAH retention

RETENTION

TIME

KILVE PAPER SHALE

KILVE BEACH SEDIMENT

STERT FLATS SEDIMENT

mlz 231 (28)

m/z 231

265

2%7R

2bR +27S i

2bR 45

2?s 285

2bR+

I

2eR

28R I

Figure 7. Partial single-ion chromatograms (MID mode) showing distributions of monoaromatic (HZ/Z = 253) and triaromatic (nz/z= 231) steroidal hydrocarbons (see Table 1 and Figure 8 for component identification). Numbers in parentheses indicate relative peak height scaling factors based on a response of 100 for the largest monoaromaric peak in each sample.

m/z253 (100)

21aR+20aS +28pR:29PS

2hR+28uS +20PR+BPS

ZhR+28aS +2tlPR+29@

246

S. D. Killops

&

V.3.

1. Identification structures)

TABLE

Terpanes 23-3 24-3 25-3 26-3 I 24-4 Ts Tm 29ab 29pa SOa/? SOba 3la/?S/R 32a/IS/R 33aBS/R 34aBS,lR 35a/?S/R Steranes 21 22 3 22-4Me 29-4Me 30-4Me I 27diaS/R 27aaR 28aaR 29aaR/S 298BIS

Monoaromatic 21 22 27/B/R 27aS/R 28/%/R 28aS/R 29/B/R 29aS/R Triaromatic 20 21 26S/R 27S/R 2gS/R

of compounds

Identification

Abbreviation Isoprenoidal Pr Ph

Howell

alkanes pristane phytane

(see Figure

(2,6,10,14-tetramethylpentadecane) (2,6,10,14-tetramethylhexadecane)

1 R = H to n-C,H,

C, tetracyclic terpane 18a(H)-22,29,30-trisnorhopane 17a(H)-22,29,30&snorhopane 17a(H),21/3(H)-30-norhopane 17/I(H),21a(H)-30-norhopane 17a(H),ZlB(H)-hopane 17@(H),2la(H)-hopane 22s and 22R isomers 1WH),WW) GG, hopanes

II

of

5a(H),14a(H),17a(H) C,, and C,, steranes C,, to C, 4-methyl 5a(H),14a(H),17a(H)

steranes

20s and 20R isomers of C,, rearranged sterane (diasterane) 5a(H),14a(H),17a(H),ZOR-cholestane 5a(H),14a(H),17a(H),20R-24-methylcholestane 20R and 20s isomers of 5a(H),14a(H),17a(H)24-ethylcholestane 20R and 20s isomers of 5a(H),14B(H),17jI(H)24-ethylcholestane

2 3 4 5a,R=H Sb, R=H Sa, R = Sb, R = 5a, R = Sa, R = Sa, R = 5a, R = Sa, R =

CH, CH, C,H, n-&H, n-C,H, n-C,H, n-C,H,,

6a(i) 6a(ii) as for other steranes + CH, at C4 7,R=H 6a(iii), 6a(iii),

R = H R = CH,

6a(iii),

R = C,H,

6b(iii),

R = C,H,

hydrocarbons

C,, and C,, monoaromatics

20s and 20R, 5/3(H) and 5a(H) of C,,-C, monoaromatics

steroidal

to in text and figures

Structure

Cz,-Cz6 tricyclic terpanes

steroidal

referred

isomers

8(i) 8(ii) S(iii), S(iii), I(iii), 8(iii), 8(iii), 8(iii),

R = R = R = R= R = R =

9(i) 9(ii) 9(iii), S(iii), 9(iii),

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

H H CH, CH, C,H, C,H,

hydrocarbons

C,, and C,, triaromatics 20s and 20R isomers C&,-C, triaromatics

of

,

8 for

Sources

and distribution

of estuarine

247

hydrocarbons

TABLE 1 (Conzinued) Polycyclic LN,DMN F DBF DBT MDBT BiPh P MP MeeP A MA PhN Fa PY BA C TPn BFa BPY Pe IPY BPe CO

aromaric

hydrocarbons” naphthalene methyl/dimethylnaphthalenes fluorene dibenzofuran dibenzothiophene methyldibenzothiophenes biphenyl phenanthrene methylphenanthrenes 4,5-methylenephenanthrene anthracene methylanthracenes phenylnaphthalene fluoranthene pyrene benz[a]anthraceneb chrysene triphenylene benzofluoranthenes* benzo[e]/[a]pyrene’ perylene ideno[ 1 ,2,3-c,d]pyreneb benzo[g,h,i]perylen2 coronene

10, X = CH2 10,x=0 lO,X=S

11

12

13 14 15 16

17

18

“Ring numbering convention for substituents is given in Figure 8. bFor structure see that of the related, unsubstituted PAH and its ring numbering in Figure 8.

system

index 269.65 (Lee et al., 1979)], were all found in relatively high quantities in the ‘ paper shale ‘, their levels in the sediments were very low. It is probable that the ‘ paper shale ’ makes a minor contribution to Bridgwater Bay sediments, but this is masked in surface sediments by a biodegraded crude oil input (Rowland & Maxwell, 1984). The presence of 2-methylthiobenzothiazole in surface sediments has previously been cited as indicating a street drainage water input, as the compound is a degradation product of a common antioxidant used in tyre manufacturing (Jungclaus et al., 1976; Spies et al., 1987). However, the presenceof this compound in the shalesample,and presumably in other petrogenic sources, together with the very low levels of benzothiazole ( < 5”,, cf. 2-methylthiobenzothiazole) detected in the sediment samples, are probably more consistent with a petrogenic origin in the sedimentsexamined here. Two possible autochthonous inputs were observed in the total aliphatic gaschromatograms of the sediments: a bacterial or algal input may account for the relatively large amount of n-undecane which was observed in the Kilve beach sediment only (Figure 3), while the predominance of n-pentadecane and n-heptadecane in both sediment samples (Figure 3) is attributable to algal origins (Youngblood et al., 1971). An input from higher-plants is probably indicated by the pronounced odd/even predominance (OEP) in the n-alkane range C23-C33(Caldicott & Eglinton, 1973), as previously noted for Bristol Channel sediment sampled at Aust (Thompson & Eglinton, 1978). During GC-MS analysis, some quinoidal compounds were identified in the total aromatic fractions of both sediments but not the ‘paper shale‘. They comprised fluoren-9-one, anthracen-9-one, anthracene-9,10-dione and benzanthracen-9-one (each

248

S. D. Killops

&

V.

3. Howell

$fjgff

slk,;b) ‘

R (ii) Y = cH3

Figure 8. Representative structures for identifications; ring numbering

(i)Y=H

of biomarker conventions

hydrocarbons and PAHs for PAHs are shown).

(see Table

1

at levels of < 109, relative to phenanthrene), and are probably photo-oxidation products of PAHs (Bjorseth & Eklund, 1979 and references therein). Sediment hydrocarbon distributions did not suggest a significant contribution from coal, although coal has been reported as a major source of PAHs, chiefly alkylated species, in certain Severn Estuary sediments (John et al., 1979). The very low levels of alkylated (short-chain) PAHs detected, which were observed only upon examination of

Sources and distribution

TABLE 2. Biomarker Stert Flats and Kilve

of estuarine h.ydrocarbons

parameters of maturity beach sediments

and source

24’)

for Kilve

Ratio”

Terpanes 32aBS/(32ajlS + 32afl)” 23-3/(23-3 + 30& 3Oub/(3Oa/?+ 30@)’ Ts/(Ts + Tm)b Xterpanes/(Zterpanes + Zsteranes)

‘ paper

shale ‘, and

(“,)

Kilve paper shale

Kilve beach sediment

Stert Flats sediment

35.2 6.0 85.1 34.1 53.8

61.2 16.2 87.7 40.3 85-O

62.1 16.0 87.9 44.5 83.6

52.4 49.6 5.5 16-2 26:29:45

42.7 45.5 5.7 15.6 30:25:45

Steranes 29aaS/(29aaS + 29aaR)” 29~/J(S+R/[29@(S+R)+29aa(S+R)]b 30-4Me/(30-4Me + CC, steranes) 27dia( S +R)/[27dia( S + R) + ZC,,steranesy C17:C&z9 (aaS +uaR steranes) /

Mono-ltri-aromatic

13.6 19.4 16.2 13.1 32:29:39

steroidal hydrocarbons

28R(tri)/[28R(tri) + 29jlR(mono) 2l(~i)/[21(tri)+28R(tri)]*~

+ 29aR(mono)]*”

16.1 3.1

38.1 31.4

46.3 13.2

“Ratios calculated from GC-MS-MID peak-area from the following ion chromatograms: m/z = 19 1 for terpanes; m/z = 217 for steranes; and m/z = 253 and 23 1 for monoand tri-aromatic steroidal hydrocarbons, respectively. See Mackenzie (1984) and references therein for a general discussion. “Maturity indicator ratios (increase with increasing maturity). ‘Source-related parameters. Calculated according to Killops and Readman, (1985).

molecular-ion chromatograms, could derive from aminor coal input or the petrogenic input (Tripp et al., 1981), or possibly from the pyrogenic input (LaFlamme & Hites, 1978). In addition to the PAHs listed in Table 3, detailed GC-MS analysis of total aromatic fractions indicated trace amounts ( < 296 cj. phenanthrene) of the following compounds in the sediments only: acenaphthene, acenaphthylene, retene, dinaphthothiophene, benzocarbazole, di(4-chlorophenyl)methanone and 4-chloroazobenzene. The two chloro compounds probably derive from agricultural activity, asdi(4-chlorophenyl)methanone is a degradation product of DDT-type compounds. Previously, no significant levels of DDT and related species were detected in Severn Estuary sediments (Cooke et al., 1979), although the methods used in that study would not have permitted detection of degradation products. Anthropogenic

PAHs

detected by GC-MS

analysis of HPLC

sub-fractions

GC-MS analysis revealed that the total aromatic fractions from the sediments were extremely complex mixtures. To examine more fully the PAHs present, 14 fractions were isolated from Kilve beach sediment total neutrals by HPLC (A-P, Figure 11). GC-FID and GC-MS analysis was performed on each aromatic sub-fraction, and a number of previously unidentified components were observed, which were also detected in Stert Flats sediment but not in the ‘ paper shale‘. Of these components, the more abundant

250

S. D. Killops

t3 V.

3.

Howell

SEDIMENT

KILVE

1 Inj

5

Figure 9. HPLC chromatograms positions of aromatic hydrocarbons

10

1s

m'"

of total neutral fractions (numbers denote elution according to their double-bond equivalent content).

(I-XII, Figure 11) are listed in Table 4 and massspectra are given in Figure 12 (conclusive identifications were not attempted). Components I-IV are probably hexahydroterphenyls [i.e. I and II are cyclohexylbiphenyls, III and IV are diphenylcyclohexanes (Killops, 19866)]. The related compounds, dicyclohexylbenzenes (i.e. dodecahydroterphenyls) and terphenyls were also present in the sediments. The ratio dodecahydroterphenyls:hexahydroterphenyls:terphenyls was cu. 12:7: 1 for both sediments, suggesting a common source. Component V appeared to exhibit a molecular ion at m/z208 (Figure 12), and probably contains six or sevendouble-bond equivalents (from HPLC retention time). Components with a molecular weight of 208 have been found in coal liquids (Boduszynski et al., 19836). Components VI and VII exhibited virtually identical massspectra (Figure 12) and probably contain seven double-bond equivalents. A component with a molecular weight

Sources

and distribution

of estuarine

mlz190+192

hydrocarbons

m/z

4MDBT

(100)

251

198

(20)

9MP

KILVE PAPER SHALE RETENTION

Figure 10. nanthrenes and Figure peak height

TIME

Partial ion chromatograms showing relative distributions of methylphe(m/z = 192 + 190) and methyldibenzothiophenes (m/z = 198) (see Table 1 8 for component identification). Numbers in parentheses indicate relative scaling factors, based on a response of 100 for the largest MP in each sample.

of 218 and exhibiting a very similar massspectrum has previously been found in coalsand sediments (Chaffee & Johns, 1983 and references therein), with the proposed structure 16,17-dihydro-15H-cyclopenta[a]phenanthrene. If component VI is this compound, then VII may be the anthracene analogue, upon comparison of the GC-retention characteristics of VI and VII with those of phenanthrene and anthracene. Related monoaromatic anthrasteroidal hydrocarbons have been identified in other sediments (Hussler & Albrecht, 1983; Brassell et d., 1984). Components with molecular weights of 302 (X) and 326 (XII) have been detected in Recent and Ancient sediments (Giger & Blumer, 1974), airborne particulate matter (Romanowski et al., 1981), coal tar (Romanowski et al., 1983; Borwitzky & Schomburg, 1979), coal liquids (Boduszynski et al., 1983a,b)and carbon black (Peadenet al., 1980; Lee & Wright, 1980). Many possible structures exist, and it is probable that the 302 molecular weight components have an empirical formula of C&H,, and contain 12 double-bond equivalents (e.g. dibenzopyrenes), and the 326 molecular weight components probably have an empirical formula of C,,H,, and contain 13 double-bond equivalents (e.g. tribenzopyrenes). Components I-XII are probably all anthropogenic PAHs, and may be of pyrogenic origin. Components V-X and alsoXII exhibited significant M*+ ions in their massspectra (Figure 12), consistent with unsubstituted polycyclic structures that, for X and XII in

252

S. D. Killops

& V.

3. Howell

3. Approximate quantification of aromatic and in Stert Flats and Kilve beach sediments

TABLE

components

in Kilve

CompositioW

Component LDicyclohexylbenzenes 2-Methylthiobenzothiazole Naphthalene ZMethylnaphthalenes Biphenyl ZMethylbiphenyls Dibenzofuran ZMethyldibenzofurans Fluorene ZMethylfluorenes Dibenzothiophene CMethyldibenzothiophenes Carbazole Phenanthrene Anthracene ZMethylphenanthrenes Phenylnapththalene Fluoranthene Pyrene LNaphthobenzothiophenes Z3 Component? ZTerphenyls Z2 Components< Benzo[a]anthracene Chrysene+ triphenylene ZBinaphthalenes ZBenzofluoranthenes Benzo[e]pyrene Benzo[a]pyrene Perylene CComponentsd Indeno[c,d-1,2,3]pyrene Benzo[g,h,i]perylene Coronene

No. doublebond equivs. 3 4 5 5 6 6 6 6 6 6 6 6 6 7 7 8 8 8 8 8 9 9 9 9 10 10 10 10 10 11 11 11 12

Mol. wt. 242 181 128 142 154 168 168 182 166 180 184 198 167 178 178 192 204 202 202 234 226 230 228 228 228 254 252 252 252 252 278 276 276 300

’ paper

shale ’

(1) ,,)

Kilve paper shale

Kilve beach sediment

Stert Flats sediment

nd. -214 113 2100 13 nd. 14 n.d. n.d. nd. 78 158 19 100 n.d. 111 2 14 12 n.d. n.d. n.d. n.d. n.d.

48 -25 34 46 12 21 19 19 19 12 9 8 4 100 34 32 10 127 103 16 -7 4 -7 38 54 4 54 22 25 9 -14 19 15

123 -25 17 25 9 23 21 22 20 13 11 12

n.d. n.d. nd. n.d. n.d. n.d.

100 26 32 12 122 78 16 -7 11 -7 39 35 45 24 24 9 - 14 19 17

n.d.

aQuantity relative to amount of phenanthrene in each sample, calculated from estimated total ion current peak heights (which could not be measured directly because of coelutions resulting from the complexity of mixtures). Molecular ion current peak heights were measured and then corrected by a factor, obtained from individual mass spectra, corresponding to the proportion of the total ion current carried by the molecular ion for each compound. Tomponents include benzo[g,h,i]fluoranthene and possibly cyclopenta[c,d]pyrene. cComponents probably include naphthacene and benzophenanthrene/benzo[b] anthracene. dComponents include dibenzanthracenes, and possibly benzochrysenes, picene and pentacene. MComponent identifications were based on mass spectra and PAH retention indices.

particular, do not readily undergo fragmentation under the conditions of electron impact (EI) GC-MS analysis employed. The majority of aromatic components (chiefly PAHs) in the sediment samples appeared to be of anthropogenic origin (Wakeham et al., 1980b and references therein). The

Sources and distribution

-

of

estuarine hydrocarbons

___-

HPLC FRACTIONATION

253

GLC ANALYSIS FRACTION D kelatrve

atten

~21

N _

I Inj

i

, 5

10

I

15’

ml”

I 150

100

I 200

-

~__

FRACTION E

FRACTION L ireiatlveatten

x21

FRACTION M (relative

atten

xl)

Figure 11. HPLC fractionation of Kilve beach sediment total neutrals and partial gas chromatograms of selected HPLC fractions. Roman numerals indicate components with mass spectra shown in Figure 12. See Table 1 and Figure 8 for component identifications. Letters in boxes show where known PAHs would elute as a comparison aid.

relatively small quantity of perylene present (Table 3) is consistent with an anthropogenie source rather than a diagenetic origin within the surface sediment (Wakeham et al., 1980~;Gschwend et al., 1983). While biogenic PAHs are known in Recent sediments (e.g. Wakeham et al., 1980a,c; Tan & Heit, 1981), no such contribution was detected in this study.

254

S. D. Killops 0 V. J. Howell

4. components

TABLE

Quantification in sediments

and

PAH

retention

indices

of

unidentified

Composition

Component

Mol. wt.

Retention index’

236 236 236 236 208 218 232 242 302 446 326

349.1 354.8 341.4 343.9 348.9 353,6/356.1 371.7d - 407’ > 500’ > 500’ > 500’

I II III IV V v1+v11 VIII IX X XI XII

No. doublebond equivs.b 6 6 6 6

617 7 7 718 12 11/12 13

aromatic

(‘I,>)

Kilve beach sediment

Stert Flats sediment

12 8 8 -1 4 16 -2 -2 -40 -20 -20

28 20 31 -2 7 17 -3 -2 -40 -20 -20

“For calculation of PAH retention index see Lee et al. (1979). bDouble-bond equivalent content based on HPLC retention time. ‘Amount relative to phenanthrene (loo”,). TAH retention index of major isomer. 400 are approximate, as picene (retention index 500) was not identified.

Composition and relative

contribution

to the sediments

of the petrogenic

source(s)

Despite the virtually identical terpane distributions (Figure 5) and the similarity of most maturity and sourceindicator ratios (Table 2) of the two sediments,there is someevidence for slight differences in the composition of the petrogenic input at the two sites. For example, maturity parameters basedon aromatic steroids differ (Table 2), and there are differences in steroid carbon-number distributions: 28R/27R for triaromatic steroidal hydrocarbons and C,,/C,, for regular steranes are, respectively, 25”,, and 23O,, higher in the Stert Flats sample. This suggeststhat the two sites have not received identical petrogenic contributions. The hopane maturity ratios based on isomerization at the C-l 7/21 and C-22 positions appear to have reached their end points, asisfrequently found at the maturity levels associatedwith crude oils (Mackenzie, 1984and references therein). Hence, these hopane maturity parameters would not be expected to reflect differing petrogenic inputs at these maturity levels. It is difficult to assessthe extent of variation in petrogenic inputs at the two sites; the similarity of terpane distributions may be fortuitous or reflect broadly similar petrogenic distributions. Nevertheless, it may be possibleto examine variation in the total amounts of petrogenic contribution at each site relative to the pyrogenic component. Table 5 lists some postulated source-related ratios, which exhibit values consistent with a greater relative petrogenic contribution in the Stert Flats sediment. The ratios LDMN/N, LTMN/MN and ZDMP/P are based on the observation that alkylphenanthrene and alkylnaphthalene distributions generally maximize at the C,/C, alkyl substituents for oils, but at the unsubstituted hydrocarbon for pyrogenic products (Van Vleet et al., 1984; see also Prahl & Carpenter, 1983) (trimethylphenanthrenes were not quantified because of their extremely low levels in both sediments). Becausethese ratios may be affected by: (i)

Sources and distribution

Figure Figure

12. Mass 11.

spectra

of

255

estuarine hydrocarbons

of selected

components

shown

in gas chromatograms

in

evaporative lossesof volatile N and MNs during sample work-up, and (ii) the more rapid photo-oxidative decomposition of MI% than 2MA and MeeP (S. D. Killops & J. W. Readman, unpubl. results) ratios based on these compounds should be compared with other source indicators. In view of such possible errors and those associatedwith component quantification, only variations of > 20% between the two sediment samplesfor the ratios given in Tables 2,5 and 6 were considered significant. It has been suggestedthat the aromatic UCM from HPLC analysis of sediment extracts can be used to monitor petrogenic contamination in the same way as the aromatic UCM from gas chromatography (Killops, 1986~; Jones et al., 1983). Larger UCMs were visible in the HPLC chromatogram (Figure 9) and in the total aromatic fraction

256

S. D. Killops

&

TABLE 5. Possible

V. J. Howell

source

indicator

ratios for Stert Flats and Kilve

beach sediments Ratio* (“o)

Kilve beach sediment L’DMN/N ZTMN/N LDMP/P Meep/EMP 2MA/.ZMP ZMDBT/ZW Cdicyclohexylbenzenes/B[a]Py Ecyclohexylbiphenyls/B[a]F’y o-terphenyl/B[a]Py (ZCzs+, triarom steroids)/B[a]Py [17a(H),2lg(H)-30-norhopane]/B[a]Py [17a(H),21/3(H)-hopane]/B[a]Py (C,,-tricyclic terpane)/B[a]Py

80 50 13 25 6 17 13 17 4 4 27 21 5

Stert flats sediment 184 89 17 20 4 23 18 29 7 20 31 22 6

#Ratios calculated from GC-MS-MID peak-area data using m/z = 191 ion chromatograms for terpanes, m/z = 231 ion chromatograms for uiaromatic steroidal hydrocarbons and molecular-ion chromatograms for other aromatic hydrocarbons. bRatios appear to decrease with increasing relative petrogenic contribution, all other ratios increase. ‘Ratio for ‘ paper shale ’ = 80.80&. TMN, trimethylnapthalene; for other component identifications see Table 1.

gas chromatogram (Figure 4) for the Stert Flats sediment. Ratios based on the gas chromatograms of total aromatic fractions gave values of UCMjPy and UCM/B[a]Py cu. 60% greater for Stert Flats sediment (calculated from UCM area, and peak heights of pyrene and benzo[a]pyrene). As Py and B[a]Py can be assumed to have an almost entirely pyrogenic origin, while the aromatic UCM has a petrogenic origin, these ratios suggest a greater relative contribution from the petrogenic than the pyrogenic source in the Stert Flats sample. However, such calculations would be expected to depend on the degree of biodegradation if significantly different petrogenic inputs were involved. A lower MeeP/CMP ratio (Table 5) appears to correlate with a greater relative petrogenie contribution in the Stert Flats sediment. This ratio has been found to be cu. lo-fold greater for pyrogenic PAHs than for oils (Gschwend & Hites, 1981; Youngblood & Blumer, 1975). The general applicability of the ratios 2MA/.XMP and CMDBT/ZMP (Table 5) has not yet been established, but these ratios seem to correlate with those discussed above. The presumably related compounds dicyclohexylbenzenes, cyclohexylbiphenyls and terphenyls were all present at levels cu. 50yb greater (cf. B[a]Py) in the Stert Flats sediment (Table 5). This enrichment value is similar to those obtained for other source-related ratios (Table 5), and so appears to be consistent with a petrogenic source for these compounds. In contrast to the source indicator ratios discussed above, those based on terpenoidal compounds (Table 5), which are relatively resistant towards biodegradation, suggest similar relative levels of petrogenic contamination in the two sediment samples. As Lterpanes:Csteranes ratio (Table 2) for the two sediments were similar, the relative

Sources

and distribution

of estuarine

TABLE 6. Alkylphenanthrene-based seven double-bond equivalent

HPLC

hydrocarbons

ratios calculated sub-fractions)

257

from

GC-FID

peak areas (using

Ratio Kilve beach sediment ZDMP/P” 2MA/ZMP” MPI-1” ZMP/P (2MP+3MP)/(lMP+9MP) See Table 1 for “The values for on component (the proportion component). *Methylphenanthrene

0.53 0.21 0.65 4.06 0.60

Stert Flats sediment

Kilve paper shale

0.77 0.15 0.53 0.84 1.35

4.20 0.09 0.47 0.68 1.45

component identifications. these ratios differ from those in Table 5 because the latter are based quantification from molecular ion intensities and not total ion current of the total ion current carried by the molecular ion varies for each Index

(Radke

& Welte,

1983).

amounts of steranes were also similar. However, relative levels of petrogenic triaromatic steroidal hydrocarbons (Table 5) were greater in the Kilve beach sediment. These biomarker ratios probably reflect differences in composition of the petrogenic component at the two sites rather than the absolute level of this input. Because these biomarkers are present in such minor amounts, a small contribution from an oil rich in one or several biomarker groups could account for these inconsistencies. Table 6 lists some ratios based on alkylphenanthrenes obtained from GC analysis. While the values of CDMPjP and 2MA/CMP in Tables 5 and 6 are not identical because of differences in the methods used to quantify the components involved (see Table 6), a correlation exists in that the Stert Flats:Kilve beach ratios for CDMP/P from Tables 5 and 6 agree, as do the ratios for 2MA/ZMP. The values of MPI-1, a maturity indicator, differ slightly for the two sediments. This is probably due to the relatively greater pyrogenic contribution of phenanthrene in the Kilve beach sediment, as other maturity parameters, such as (2MP + 3MP)/( 1MP + 9MP) and those based on steroidal biomarkers (Table 21, gave quite similar values for the two petrogenic sources. Preferential association of PAHs with coarse-grained and of alkanes with fine-grained sedimentary material has been observed previously in Severn (Brassell & Eglinton, 1980) and other estuarine sediments (Readman et al., 1984). Similarly, in the present study the Kilve beach sediment contained a higher proportion of coarse-grained material and appeared to exhibit a relatively greater contribution from pyrogenic PAHs. However, it is unlikely that particulate associations are governed entirely by particle size/surface area absorption factors. Indeed, simple equilibrium models of PAH sorption/desorption from aqueous phase on to small particles of high surface area does not appear to account for the behaviour of PAHs (Prahl & Carpenter, 1983). The importance of particulate surface chemistry and initial input associations requires evaluation. Total alkane gas chromatograms for the two sediments (Figure 3) were similar to that previously reported for Severn Estuary sediment taken at Aust (Thompson & Eglinton, 1978). All three sediments exhibited a biomodal UCM (with maxima at cu. n-C,, and n-C,, alkane elution positions). This has been interpreted as evidence for at least two

258

S. D. Killops

&

V.

3. Howell

sources of crude oil input (Thompson & Eglinton, 1978), which seems very probable. However, in the Aust sediment study (Thompson & Eglinton 1978), the UCM maximum at cu. n-C,, was more pronounced, and the relative quantities of pristane and phytane were lower than observed in Figure 3. These observations may well result from differences in the petrogenic sources at the various sites, but other explanations exist, and the UCM differences may also be attributable to the effects of sample fractionation techniques (Killops, 1986~). Nevertheless, continuing biodegradation and weathering would be anticipated to affect n-alkane and biomarker distributions from a single pollution event. Therefore, the similarity of biomarker distributions observed in this study (Figures 3,5, 6 and 7) to those reported in previous studies (Thompson & Eglinton, 1978; Brassell & Eglinton, 1980; Rowland & Maxwell, 1984) may reflect chronic petrogenic contamination. Conclusions Detailed analysis of biomarker hydrocarbons and total aromatic fractions by GC-MS failed to provide evidence for a reworked contribution from the Kilve ‘ paper shale ’ to two Bridgwater Bay, intertidal, surface (top 20 cm) sediments sampled on Stert Flats and Kilve beach. Two major sources of hydrocarbons in the sediments were recognized: (i) a biodegraded, petrogenic input, characterized by its biomarker distributions and aromatic UCM; and (ii) an input of pyrogenic, non-alkylated PAHs. In addition, evidence was also found of algal and higher plant hydrocarbon inputs to both sediments. While some differences were noted in biomarker distributions from the petrogenic source(s) between the two sediments, they were broadly similar to each other and to those described in previous studies on Severn Estuary sediments (Thompson & Eglinton, 1978; Brassell & Eglinton, 1980; Rowland & Maxwell, 1984). These observations may be consistent with chronic contamination from generally the same source(s), and could reflect seasonal resuspension and mixing of sedimentary material within Bridgwater Bay (Uncles, 1984; Dyer, 1984 and references therein), resulting in a broadly homogeneous distribution of petrogenic components throughout the Bay [and possibly over a wider area, upon comparison of biomarker data from Aust (Thompson & Eglinton, 1978; Brassell & Eglinton, 1980), cu. 50 km upstream from site c, Figure 11. On this basis, the slight differences noted in distributions of some steroidal biomarkers could result from an exclusive petrogenic input at one site that occurred since the last resuspension and mixing episode. However, this model must remain speculative without knowledge of the significance of the observed biomarker differences. A variety of source-related parameters suggested that the finer-grained Stert Flats sediment had a greater petrogenic input relative to the pyrogenic source of hydrocarbons (possibly as much as 50:/, greater than the Kilve beach sediment), if the samples studied can be considered typical. This may be accounted for by the disproportionate distribution of alkanes and PAHs between fine- and coarse-grained material previously observed in estuarine sediments (Brassell & Eglinton, 1980; Readman et al., 1984), although other studies (Prahl & Carpenter, 1983) suggest that speciation of PAHs is almost certainly more complex than suggested by a simple particle surface-area absorption model. Hydrodynamic sorting of sedimentary material according to density (Dyer, 1984 and references therein) could further increase differences in relative concentrations of alkanes and PAHs at various locations. Work is in hand to determine whether petrogenic inputs behave as discrete phases in their particle associations, or whether different adsorption processes

Sources and distribution

of

estuarine hydrocarbons

259

effect some fractionation, e.g. fractionation of aliphatic and aromatic components. The significance of initial input associationsalso requires attention. HPLC of total aromatic fractions from the Bridgwater Bay sediments indicated the presenceof an extended range of apparently anthropogenic PAHs, with molecular weights of up to 326 being detected by GC-MS analysis. A group of inter-related components was alsoobserved comprising terphenyls, cyclohexylbiphenyls and dicyclohexylbenzenes, all present in relatively greater quantities in the Stert Flats sediment, which suggeststhey originate from the petrogenic source(s). These hydroterphenyls may provide a useful indicator of relative levels of petrogenic contamination in other sediments,where they are present, asthey would be anticipated to be relatively resistant towards biodegradation. Acknowledgements Thanks are extended to Masspec Analytical for the use of facilities, and to James Readman, Alison Bradshaw and Alison Partridge for their help during this study. References Bjorseth, A. & Eklund, G. 1979 Analysis of polynuclear aromatic hydrocarbons by glass capillary gas chromatography using simultaneous flame ionisation and electron capture detection. 3ouwzaZ of High Resolution Chromatography & Chromatography Communications 22-26. Boduszynski, M. M., Hurtubise, R. J., Allen, T. W. & Silver, H. F. 1983a Liquid chromatography/field ionization mass spectrometry in the analysis of high-boiling and nondistillable coal liquids for hydrocarbons. Analytical Chemistry 55,225231. Boduszynski, M. M., Hurtubise, R. J., Allen, T. W. & Silver, H. F. 19836 Determination of hydrocarbon composition in high-boiling and nondistillable coal liquids by liquid chromatography/field ionization mass spectrometry. Analytical Chemistry 55,232-241. Borwitzky, H. & Schomburg, G. 1979 Separation and identification of polynuclear aromatic compounds in coal tar by using glass capillary chromatography including combined gas chromatography-mass spectrometry.JournalofChromatography 170,99-124. Brassell, S. C. & Eglinton, G. 1980 Environmental chemistry-an interdisciplinary subject. Natural and pollutant organic compounds in contemporary aquatic environments. In Enwironmenral Chemistry (Albaiges, J., ed.). Oxford: Pergamon Press, pp. l-22. Brassell, S. C., McEvoy, J., Hoffmann, C. F., Lamb, N. A., Peakman, T. M. & Maxwell, J. R. 1984 Isomerisation, rearrangement and aromatisation of steroids in distinguishing early stages of diagenesis. In Advances in Organic Geochemistry 1983 (Schenck, P. A., De Leeuw, J. W. & Lijmbach, G. W. M., eds). Oxford: Pergamon Press, pp. 1 l-23. Caldicott, A. B. & Eglinton, G. 1973 Surface waxes. In I’hytochemistry III, Inorganic Elements and Special Groups of Chemicals (Miller, L. P., ed.). New York: Van Nostrand Rheinhold, pp. 162-194. Chaffee, A. L. &Johns, R. B. 1983 Polycyclic aromatic hydrocarbons in Australian Coals. I. Angularly fused pentacyclic tri- and terra-aromatic components of Victorian brown coal. Geochimica ef Cosmochimica Acta 47,2141-2155. Cooke, M., Nickless, G., Povey, A. & Roberts, D. J. 1979 Poly-chlorinated biphenyls, poly-chlorinated naphthalenes and polynuclear aromatic hydrocarbons in Sevem Estuary (U.K.) sediments. Science of the Total Environment 13,17-26. Dyer, K. R. 1984 Sedimentation processes in the Bristol Channel/Sevem Estuary. Marine Poflurion Bulferin 15,53-57. Giger, W. & Blumer, M. 1974 Polycyclic aromatic hydrocarbons in the environment: isolation and characterisation by chromatography, visible, ultraviolet, and mass spectrometry. Analytical Chemistry 46,1663-1671. Glover, R. S. (ed.) 1984 The Bristol Channel and Sevem Estuary. Marine Pollution Bulletin 15,37-81. Gschwend, P. M. & Hites, R. A. 1981 Fluxes of polycyclic aromatic hydrocarbons to marine and lacustrine sediments in the northern United States. Geochimica et Cosmochimica Acta 45,2359-2367. Gschwend, P. M., Chen, P. H. and Hites, R. A. 1983 On the formation of perylene in recent sediments: kinetic models. Geochimica er Cosmochimica Acta 47,2115-2119. Hussler, G. & Albrecht, P. 1983 C,,-C, Monoaromatic anthrasteroidal hydrocarbons in Cretaceous black shales. Nature 304,262-263.

260

John,

S. D. Killops

t3 V. J. Howell

E. D., Cooke, M. & Nickless, G. 1979 Polycyclic aromatic hydrocarbons in sediments taken from the Severn Estuary drainage system. Bulletin of Environmental Contamination and Toxicology 22,65%659. Jones, D. M., Douglas, A. G., Parkes, R. J., Taylor, J., Giger, W. & Schaffner, C. 1983 The recognition of biodegraded petroleum-derived aromatic hydrocarbons in recent marine sediments. Marine Pollution Bulletin 14,103-108. Jungclaus, G. A., Games, L. M. & Hites, R. A. 1976 Identification of trace organic compounds in tire manufacturing plant wastewaters. Analytical Chemistry 4818941896. Killops, S. D. 1986a Identification of petrogenic contamination in Recent sediments by HPLC monitoring of aromatic components. A preliminary investigation. Chemosphere 15,229-241. Killops, S. D. 19866 Normal phase HPLC retention characteristics of polycyclic aromatic hydrocarbons on cyano/amino bonded silica. Journal of High Resolution Chromatography & Chromatography Communications 9,302-303. Killops, S. D. & Readman, J. W. 1985 HPLC fractionation and GC-MS determination of aromatic hydrocarbons from oils and sediments. Organic Geochemistry 8,247-257. LaFlamme, R. E. & Hites, R. A. 1978 The global distribution of polycyclic aromatic hydrocarbons in recent sediments. Geochimica et Cosmochimica Acta 42,289-303. Lee, M. L. &Wright, B. W. 1980 Capillary column gas chromatography of polycyclic aromatic compounds: a review. Journal of Chromatographic Science 18,345-358. Lee, M. L., Vassilaros, D. L., White, C. M. & Novotny, M. 1979 Retention indices from programmedtemperature capillary-column gas chromatography of polycyclic aromatic hydrocarbons. Analytical Chemistry 51,768-773. Mackenzie, A. S. 1984 Applications of biological markers in petroleum geochemistry. In Advances in Perroleum Geochemistry, Vol 1 (Brooks, J. & Welte, D., eds). London: Academic Press, pp. 115-214. Morris, A. W. 1984 The chemistry of the Severn Estuary and the Bristol Channel. Marine Pollution Bulletin l&57-61. Peaden, I’. A., Lee, M. L., Hirata, Y. & Novotny, M. 1980 Higher-performance liquid chromatographic separation of high-molecular-weight polycyclic aromatic compounds in carbon black. Analytical Chemistry 52,2268-2271. Prahl, F. G. & Carpenter, R. 1983 Polycyclic aromatic hydrocarbons @‘AH)-phase associations in Washington coastal sediment. Geochimica et Cosmochimica Acta 47, 10131023. Radke, M. & Welte, D. H. 1983 The methylphenanthrene index (MPI): a maturity parameter based on aromatic hydrocarbons. In Advances in Organic Geochemistry 1981 (Bjoroy, M. et al., eds). New York: Wiley, pp. 504-512. Readman, J. W., Mantoura, R. F. C. & Rhead, M. M. 1984 The physico-chemical speciation of polycyclic aromatic hydrocarbons (PAH) in aquatic systems. Fresenius 2. Analyt. Chem., 319,126-131. Romanowski, T., Funcke, W., KBnig, J. & Balfanz, E. 1981 Detection of PAH of molecular weight between 300 and 402 in airborne particulate matter by fused silica capillary GC and GC/MS. Journal of High Resolution Chromatography & Chromatography Communications 4,209214. Romanowski, T., Funcke, W., Grossmann, I., K&rig, J & Balfanz, E. 1983 Gas chromatographic/mass spectrometric determination of high-molecular-weight polycyclic aromatic hydrocarbons in coal tar. Analytical Chemistry .5.5,1030-1033. Rowland, S. J. & Maxwell, J. R. 1984 Reworked triterpenoid and steroid hydrocarbons in a recent sediment. Geochimica et Cosmochimica Acta 48,61’7-624. Spies, R. B., Andresen, B. D. &Rice, D. W. 1987 Benzthiazoles in estuarine sediments as indicators of street ntnoK Nature 327,697-699. Tan, Y. L. & Heit, M. 1981 Biogenic and abiogenic aromatic hydrocarbons in sediments from two remote Adirondack lakes. Geochimica et Cosmochimica Acta 45,2267-2279. Thompson, S. & Eglinton, G. 1978 Composition and sources of pollutant hydrocarbons in the Severn Estuary. Marine Pollution Bulletin 9,133136. Tripp, B. W., Farrington, J. W. & Teal, J. M. 1981 Unburned coal as a source of hydrocarbons in surface sediments. Marine Pollution Bulletin 12, 122-126. Uncles, R. J. 1984 Hydrodynamics of the Bristol Channel/Sevem Estuary, Marine Pollution Bulletin 15, 47-53. Van Vleet, E. S., Peirce, R. H., Brown, R. C. & Reinhardt, S. B. 1984 Sedimentary hydrocarbons from a subtropical marine estuary. In Advances in Organic Geochemistry 1983 (Schenck, P. A., De Leeuw, J. W. & Lijmbach, G. W. M., eds). Oxford: Pergamon Press, 249-257. Wakeham, S. G., Schaffner, C. & Giger, W. 1980a Diagenetic polycyclic aromatic hydrocarbons in recent sediments: structural information obtained by high performance liquid chromatography. In Advances in OrganicGeochemistry 1979(Douglas,A. G. &Maxwell, J. R.,eds). Oxford: PergamonPress,pp. 353-363. Wakeham, S. G., Schafhrer, C. St Giger, W. 19806 Polycyclic aromatic hydrocarbons in recent lake sediments-I. Compounds havinganthropogenicorigins. Geochimica et Cosmochimica Acta 44,403-413. Wakeham, S. G., Schaflirer, C. & Giger, W. 1980~ Polycyclic aromatic hydrocarbons in recent lake sediments-II. Compounds derived from biogenic precursors during early diagenesis. Geochimica et Cosmochimica Acta 44,415-429.

Sources

and distribution

of estuarine

hydrocarbons

261

Youngblood, W. W. & Blumer, M. 1975 Polycyclic aromatic hydrocarbons in the environment: homologous series in soils and recent marine sediments. Geochimica et Cosmochimica Acta 38, 1303-1314. Youngblood, W. W., Blumer, M., Guillard, R. R. L. & Fiore, F. 1971 Saturated hydrocarbons in marine benthic algae. Marine Biology 8, 190-201.