Characteristics and Source of Polycyclic Aromatic Hydrocarbons In

Geochemical Journal, Vol. 46, pp. 31 to 43, 2012

Characteristics and source of polycyclic aromatic hydrocarbons in the surface hydrothermal sediments from two hydrothermal fields of the Central Indian and Mid-Atlantic Ridges

JIWEI LI,1,2 XIAOTONG PENG,3* HUAIYANG ZHOU,3 JIANGTAO LI,3 SHUN CHEN,3 ZIJUN WU3 and HUIQIANG YAO2

1Southwest Jiaotong University, Chengdu 610031, China 2Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China 3State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China

(Received March 24, 2011; Accepted November 2, 2011)

The analysis of major elements and polycyclic aromatic hydrocarbons (PAHs) were carried out on surface hydrothermal sediments collected from the Kairei hydrothermal field on the Central Indian Ridge (CIR) and the Logatchev hydrothermal field on the Mid Atlantic Ridge (MAR). The most characteristic PAHs in the samples were the low molecular weight (LMW) analogs present in a significantly high proportion. Values of the fluoranthene/pyrene (F/P) ratio indicated that PAHs originated from a pyrolytic process. The relative abundance of phenanthrene and its alkyl homologs character-

ized by the following order C0 > C1 > C2 > C3 > C4, and this result suggested that less biodegradation had occurred in the hydrothermal organic matter. However, a severe secondary oxidation or thermal loss of Benzo[a]pyrene (BaP) would have happened due to the presence of Benzo[e]pyrene (BeP) and absence of BaP in the PAHs. The hierarchical cluster analysis (HCA) showed that these samples could be grouped into four clusters, and all members in the same cluster had a similar inorganic geochemical characteristic. On the basis of canonical correspondence analysis (CCA), the PAH compositions were correlated well with those of inorganic elements. Among them, LMW PAHs such as biphenyl, naphthalene and fluorene were more related to the Talc formation environment, where the Si rich fluids meet the Mg rich seawater. These intermediate weight (IMW) PAHs such as phenanthrene, dibenzothiophene and retene showed a positively relation with metal elements (Fe, Cu and Zn), which may represent a plume fall-out environment. Lastly, the high molecular weights (HMW) PAHs including chrysene, fluoranthene and BeP showed a major positive correlation with environment of the chimney wall. These results suggest that the different molecular weight PAHs might be prone to distribute in different hydrothermal occurrence among the hydrothermal system.

Keywords: polycyclic aromatic hydrocarbons, inorganic geochemical characteristic, hydrothermal sediments, Kairei hydrothermal field, Logatchev hydrothermal field

carbon, and subsequently migrate to surficial sediments INTRODUCTION (Pikovskii et al., 1996; Rudenko and Kulakova, 1986; PAHs are believed to be formed under high-tempera- Chernova et al., 1999). For example, Konn and coworkers ture synthesis, incomplete burning of organic fuel or as a detected the aromatic compounds in the hydrothermal flu- result of thermal impact on organic matter (Simoneit, ids from the Rainbow and Lost city hydrothermal fields 1993, 1995; Rudenko and Kulakova, 1986; Gennadiyev in the MAR region (Konn et al., 2009), and after that, et al., 1996). They are not only the indicator of industrial through the simulation experiment, they proved that PAHs and municipal contamination (Budzinski et al., 1997), but could be formed by biomass degradation in the extremely also one of the major components of hydrotherma1 bitu- hydrothermal environment (Konn et al., 2011). Since the men (Simoneit, 1984; Kawka and Simoneit, 1990). Both first discovery of hydrothermal petroleum at the Guaymas field study and laboratory simulation indicated that these Basin in the Gulf of California in 1978 (Simoneit et al., thermogenic hydrocarbons were likely to form from the 1979), numerous studies devoted to investigation of PAHs deep in the high temperature zone within the earth crust in the hydrothermal field have been carried out. Espe- as a result of synthesis and polycondensation of simple cially, in the Escanaba Trough on the southern Gorda Ridge (Kvenvolden et al., 1986), the Middle Valley of the Juan de Fuca Ridge (Simoneit, 1994), the Red Sea *Corresponding author (e-mail: [email protected]) (Simoneit et al., 1987; Michaelis et al., 1990), the Copyright © 2012 by The Geochemical Society of Japan. Andaman Basin (Chernova et al., 2001; Venkatesan et al.,

31 Logatche

Edmond

Meters Meters –3000 –2800 TVG13 –3100 –3400 Legend MAR6 –3400 –3800 MAR1

Hydrothermal field

Sample site

CIR7

Fig. 1. Locations of sampling sites at the Kairei and Edmond hydrothermal fields in CIR and the Logatchev hydrothermal field in MAR.

2003), the Rainbow vent field (Simoneit et al., 2004; Konn By contrast, the PAHs profiles in the hydrothermal solid et al., 2009) and the Lost City hydrothermal field structures, such as sulfide deposits (Simoneit et al., 2004) (Delacour et al., 2008; Konn et al., 2009). and chimneys (Simoneit and Fetzer, 1996), are charac- These previous investigations have made a great ad- terized by high concentrations of heavy PAHs (e.g., vancement in the knowledge of modern marine hydro- coronene) and only traces of LMW PAHs. thermal organic matter and provided a large amount of Based on the analysis of sulfide deposit at the rain- useful information to compare with the ancient counter- bow hydrothermal field, Simoneit et al. (2004) suggested parts found on land. However, the spatial distribution of that the solubility of the LMW PAHs was high enough PAHs in the hydrothermal geological occurrence at mod- for them to dissolve in the fluids. This factor resulted in ern marine hydrothermal fields is still a hot topic. the HMW PAHs analogs were abundant and LMW PAHs Chernova et al. (1999) reported that sediments in the analogs were depleted in the chimney walls at the rain- tectonically active zones of central part of the Andaman bow hydrothermal field (Simoneit et al., 2004). There- basin contained 10–100 times more hydrocarbons than fore, we hypothesized that the LMW PAHs would be apt pelagic sediments of the deep water basins in Indian to dissolve in the venting fluid and be transported out of Ocean, and concluded that the high levels of LMW ana- the hydrothermal chimney to the hydrothermal sediment logs PAHs, including naphthalene, phenanthrene and bi- around the hydrothermal deposit, whereas the HMW com- phenyl, in the deformation zone were associated with the ponents would be entrapped or redeposited from high tem- hydrothermal process. Venkatesan et al. (2003) also found perature fluid to the bitumen in the chimneys. This hy- that hydrothermal surface sediments of the Andaman pothesis sounds reasonable, however, it need more evi- backarc basin in Indian Ocean were predominated by alkyl dences to prove it. Here, we examined the relative abun- naphthalenes and alkyl phenanthrenes. Thus, this suggests dance of PAHs and concentration of major elements in that the low molecular weight PAHs would be commonly the hydrothermal surface sediments of two hydrothermal present in the surface sediments of hydrothermal systems. fields from two distantly geographic locations (CIR and

32 J. Li et al. Table 1. Sample location and description

Sample Sample site Brief characteristics Main mineral Central Indian Ridge TVG 13 69.60°E, 23.88°S Fragment of sulfides chimney anhydrite Edmond hydrothermal field CIR7-1 70.04°E, 25.32°S Brown-yellow sediments with minor soft white sediment talc Kairei hydrothermal field CIR7-2 Gray-white soft sediment with some coarse grains talc, sphalerite CIR7-3 Gray-yellow sediments with some coarse grains talc CIR7-4 White and yellow sediment with dark-coffee coarse grains talc, chalcopyrite

Mid Atlantic Ridge MAR1-1 44.98°W, 14.75°N Gray-white soft muddy sediments calcite Logatchev hydrothermal field MAR1-2 Red-brown metalliferous sediment Fe-oxyhydroxide MAR1-3 Dark-brown metalliferous sediment Fe-oxyhydroxide MAR6-1 44.98°W, 14.75°N White muddy sediment calcite

MAR) to test the possibility of the occurrence of such ized by high contents of iron, silica, high H2S with high kind processes. chlorinity and low pH (Gallant and Von Damm, 2006).

The Logatchev hydrothermal field GEOLOGICAL SETTING The hydrothermally active Logatchev field is located The Edmond and Kairei hydrothermal fields at 14°45′ N and 44°58′ W on a plateau immediately be- The Kairei vent field is located at 25°19′ S, 70°02′ E low a 350 m high cliff at a water depth of 3060–2900 m in segment S1 immediately north of the Rodriguez Triple (Fig. 1). Hydrothermal activity was first documented in Junction on the Central Indian Ridge (Gamo et al., 2001). 1994 along the eastern wall (Batuev et al., 1994). It ex- The hydrothermal activity was first reported by Herzig tends at least 800 m NW-SE and 400 m SW-NE and shows and Plüger (1988), and the hydrothermal vent site was a high diversity of vent sites and associated fauna. In this also first directly observed in 2000 (Hashimoto et al., area, tectonic accretion dominates the basaltic magma 2001). The main area of high temperature venting in this supply, resulting in a tectonic uplift of mantle and lower hydrothermal field occurs along a WNW trend, extends crustal rocks (peridotites and gabbros) to the sea-floor 80 m along the rift wall and is 30 m wide. The vent fluids (Cannat et al., 1997). Two main areas of high-tempera- of the Kairei hydrothermal field have a very high con- ture hydrothermal activity form the central part of the centration of hydrogen gas, a relatively high concentra- field, which is an area of at least three smoking craters, tion of silicon and a remarkably low CH4/H2 ratio. Large and a large mound with black smoker chimneys at its top. accumulations of weathered sulfides and peripheral rel- Black smoke is venting intensely at all three sites, either ict sulfide chimneys suggest the site has been active for a from the chimneys on the crater rim or from holes in the long time and there has been migration or focusing of sea-floor within the craters. Hydrothermal plumes and flow to the current configuration of three high-tempera- orange-brown iron oxyhydroxide sediments are common ture mounds (Van Dover et al., 2001). at this site. The Edmond hydrothermal field (Fig. 1), located at 23°53′ S, 69°36′ E at a depth of ~3300 m, is approxi- SAMPLES AND METHODS mately 160 km NNW of the Kairei vent field on the CIR. The vent field (100 m × 90 m) is on a small protrusion Samples that extends south from the eastern rift wall, which forms Samples were collected by TV-grab during the cruise the northeastern corner of a 60 m deep basin. High tem- of R/V DA YANG YI HAO conducted by China Ocean perature venting is manifested as discrete clusters of large Mineral Resource R&D Association (COMRA) in 2005 chimneys with vigorous black-smoker fluids emanating (Fig. 1). Sites, water depths and description of samples from multiple orifices and “beehive” structures (Van are summarized in Table 1. The CIR7 hydrothermal sedi- Dover et al., 2001). High temperature venting at this site ment was collected on the seafloor surface at the Kairei is focused along a NW-SE trend and is likely to be fault- hydrothermal field at 70.04°E, 25.32°S at a depth of 2450 controlled. Hydrothermal fluid in this field is character- meters. CIR7 was divided into four sub-samples (CIR7-

Characteristics and source of polycyclic aromatic hydrocarbons in the hydrothermal sediments 33 1, 2, 3 and 4) having different colors and composition. were separated on a fused silica capillary column (DB-5; MAR1 hydrothermal sediment was collected from the length, 30 m; i.d., 0.25 mm; film thickness, 0.25 mm) seafloor surface at the Logatchev hydrothermal field at and detected by flame ionization. The GC oven tempera- 44.978°E, 14.753°S at a depth of 3046 m in the MAR. ture were programmed from 80°C to 230°C at 3°C/min, The sample, which was composed of dark-brown and red- and from 230°C to 310°C at 2°C/min, then kept at 310°C brown metalliferous sediments as well as gray-white soft for 15 min. muddy sediments, was divided into three subsamples The GC-MS system (HP 6890 GC Plus trace-MS se- (MAR1-1, 2 and 3). MAR6-1 and TVG13 were used as lective detector) used a fused silica capillary column (HP- reference samples. MAR6-1 a surface sediments was col- 5; length, 30 m; i.d., 0.25 mm; film thickness, 0.25 mm) lected at 44.978°(E), 14.751°(S) outside the Logatchev in selected ion monitoring (SIM) and helium as the car- hydrothermal field at a depth of 2992 m. It consists mainly rier gas. The injection port, interface line, and ion source of calcites and exhibits little sign of hydrothermal altera- temperature were maintained at 250°C. The GC oven tem- tion. TVG13, a fragment of sulphide chimney that was perature was programmed from 50 to 300°C at 8°C/min, collected from the Edmond hydrothermal field on the CIR, with a final isothermal hold for 30 min at 300°C. PAH was used for comparison with the hydrothermal were identified by comparison of retention times and mass sediments. All samples were frozen (–20°C) in spectra with authentic standards (Supelco Inc.). The mass polyethylene bags immediately after collection and stored spectra were determined by electron impact at 70 eV. A 1 as such. µl volume of each sample was injected manually in the split-less mode. PAHs were identified by comparison of Analytical procedures retention times and mass spectra with authentic stand- Samples for inorganic analysis were rinsed three times ards. with deionized water, dried in the oven at 60°C, and then powdered in an agate mortar to 200 meshes. X-ray dif- Multivariable statistics analysis fraction (D/max-2550VB3, Rigaku, Cu radiation, 35 kV Hierarchical cluster analysis (HCA) is used for find- and 30 mA, scan rate 2°/min, 5°–75° 2θ) of bulk samples ing the similarity among the different samples. For HCA, was used to characterize the mineralogy of the sediments. each PAHs profile of relative concentration in the hydro- For elemental analysis, the sub-samples were burnt at thermal sediments was treated as a multiple variable, and 700°C about 2 hours. Sub-samples of 50 mg were accu- the nearest neighbor was used for clustering by calculat- rately weighed and digested with an HNO3–HCl–HF– ing the distance between variables. Clustering was made HClO mixture in air-tightly Teflon container. The digests by calculating the squared euclidean distance of variables. were evaporated to dryness, and then dissolved in 2% As was done for PAHs relative concentration, HCA was HNO3 and diluted the final volume up to 50 ml. The carried out on the sampling sites used the SPSS 11.5 for concentration of major elements was determined by in- windows software package (SPSS, USA). To perform a ductively coupled plasma/atomic emission spectrometry statistical analysis of the PAH composition versus the (ICP/AES, PerkinElmer Optima 2000 DV) with a preci- major inorganic elements, we chose canonical correspond- sion of 5%. ∑S and Si quantified by titration with a pre- ence analysis (CCA). It is a method combined with cor- cision of 5%. All the inorganic analyses were carried out respondence analysis and multiple regression analysis, at the Key Laboratory of Isotope Geochronology in the and every step of the calculations for the regression with Guangzhou Institute of Chinese Academy of Sciences environmental factor (ter Braak, 1986). Primarily it is used (CAS). to depicting the correspondence analysis between the Samples for organic analysis were freeze-dried and environmental factor and biological species (e.g., Dang then ground in a mortar to 100 meshes before extraction. et al., 2008). In this study, we define the inorganic major Bitumen was extracted from the dried sediments and one elements as the environmental factor and the PAH com- blank sample (no sediments) with benzene/methanol (3:1 position (the sum of parent PAH and its alkylated by vol.) using ultrasonication three times. The combined homologs) as the species. This analysis was carried out solvent extract was concentrated and treated with acti- using CANOCO 4.5 software package (Biometris, Neth- vated Cu to remove S, dried under a gentle flow of puri- erlands) and the ordination plots for species and environ- fied N2 and then weighed (Mettler AG285 analytical bal- mental variables were characterized by biplots. ance). After extraction, the bitumen was separated into aliphatic, aromatic, and asphaltic (NSO) compounds by RESULTS silica-gel column chromatography as described by Simoneit and Lonsdale (1982). Major elements The aromatic fractions were analyzed with gas chro- The concentrations of major elements were given in matograph (HP 6890) using helium as a gas carrier. They Table 2. All CIR7 sub-samples had high concentrations

34 J. Li et al. Table 2. Major element composition of the hydrothermal sediment samples from CIR and MAR

TVG13 CIR7-1 CIR7-2 CIR7-3 CIR7-4 MAR1-1 MAR1-2 MAR1-3 MAR6-1

∑S(%) 20.9 0.1 1.2 0.2 1.7 0.4 0.9 0.4 0.2 Fe(%) 3 1.7 1.3 1 2.5 5.5 31 29.2 0.7 Si(%) 0.1 26.2 26.6 27.7 24.6 8.1 0.3 10.1 2.2 Al(%) 0.1 0.7 0.4 0.1 0.1 1.6 0.1 0.9 0.7 Ca(%) 30.1 0.5 0.3 0.2 0.1 21.6 9.5 0.5 25.8 Zn(%) 0.1 0.2 1 0.1 0.2 0.6 0.8 0.2 0.01 Cu(%) 0.1 0.4 0.2 0.1 0.8 0.5 2.9 0.3 0.01 Mg(%) 0.1 17.3 14.1 7.6 7.7 0.9 0.3 0.6 0.4

of Si (24.6–27.7%) and Mg (7.6–17.3%), with lower con- dibenzofluoranthene, fluoranthenes and pyrene showed centrations of Fe (1.0–2.5%). Talc was the main mineral a similar trend (Table 3). in these samples. The presence of Zn (1%) in CIR7-2 and The ratio of fluoranthenes/pyrene (F/P) was also cal- Cu in CIR7-4 were related to the occurrence of minor culated, ranged from 1.85 to 2.86 in the CIR samples and sphalerite and chalcopyrite, respectively. MAR1 sub- 1.88 to 2.61 in the MAR samples, respectively (Table 3). samples had concentrations of Fe that were much higher Significant amounts of BeP were detected in all samples than those of other samples (5.5–31.0%, Table 2). MAR1- and were in a range of 0.5–1.12% (Table 3). However, 1 and MAR1-2 had high contents of Ca (21.6% and 9.5%, the Bap was absent. Retene was also observed in all sam- respectively). Except MAR1-2, the MAR1 sediments had ples and represented from 0.92% to 3.32% of the tPAHs significant amounts of Si. The main minerals were cal- with the highest value at MAR1-3 (Table 3). cites in MAR1-1 and amorphous Fe-oxyhydroxides in MAR1-2 and MAR1-3. MAR6-1 was collected near the Multivariable statistics analysis Logatchev hydrothermal field, Ca was the dominant ele- HCA showed that these samples could be grouped into ment and calcite was the main mineral. There were sig- four clusters as follow: (I) CIR7-1, CIR7-2 and CIR7-3; nificant amounts of S (20.9%) and Ca (30.1%) in TVG13 (II) MAR1-1 and MAR6-1; (III) MAR1-2, MAR1-3 and and its main mineral was anhydrite (Table 1), which was TVG13, and (IV) CIR7-4 (Fig. 5). typical of the exterior of a sulfide chimney. In our CCA analysis (Fig. 5), Si, Mg, S, Ca elements emerged as significant factors affecting the composition Polynuclear aromatic hydrocarbons of the PAHs in this study. Furthermore, the result revealed PAHs were detected in all these samples (except of that the PAHs in these hydrothermal sediments could be the blank one) and comprised both parent and their grouped into three major groups (Fig. 6). Fluorene, alkylated homologs as listed under Table 3 and Fig. 2. dibenzofuran, biphenyl and naphthalene, the four LMW The representative ion total current profile of PAH frac- PAHs (2 rings and 3 rings) displayed a major correlation tion was shown in Fig. 3. In this study, parent PAHs had with Si and Mg elements. Phenanthrene, a large proportion ranged from 52.12% to 59.94% in to- dibenzothiophene, and retene, the three IMW PAHs (3 tal PAHs (tPAHs; Table 3). Furthermore, the relative abun- rings and 4 rings) were positive influenced by the Fe, Cu dances of individual parent PAHs occurred generally fol- and Zn. The relative HMW PAHs such as BeP, chrysene, lowing this order: phenanthrene > fluoranthene > pyrene, fluoranthene, benzofluoranthene and pyrene (mainly 4 fluorene > retene > dibenzothiophene > dibenzofuran, BeP rings and 5 rings), showed a major positive correlation > benz[a]anthracene > naphthalene (Table 3). For the with S and Ca elements. In addition, benz[a]anthracene tPAHs, LMW PAHs (2 and 3 rings) such as naphthalene, was a special PAH, which showed minor negatively cor- phenanthrene, and fluorene, were the most abundant com- relation with the Fe, Cu and Zn elements. ponents, followed by the 4 rings PAHs (e.g., fluoranthene, pyrene), and HMW PAHs (5 rings, e.g., BeP) were the DISCUSSION least (Fig. 4). Among them, the triaromatic PAHs— phenanthrene and its alkyl homologs were the most domi- The hydrothermal environment indicated by the inorganic nant abundant suite of PAHs in all the samples, which elements constituted of 41.10% to 53.34% of the tPAHs. Addition- Si and Mg element are in a high concentration in the ally, the relative abundance of phenanthrene and its alkyl CIR7 sediments, where the talc is the mainly mineral. The homologs followed an order C0 > C1 > C2 > C3 > C4 in origin of talc in ocean-floor settings can be related to one mostly samples. The homologs of fluorene, of the following three main processes: (a) direct precipi-

Characteristics and source of polycyclic aromatic hydrocarbons in the hydrothermal sediments 35 Table 3. Concentration of various PAHs in the hydrothermal sediment samples from CIR and MAR

CIR7-1 CIR7-2 CIR7-3 CIR7-4 MAR1-1 MAR1-2 MAR1-3 MAR6-1 TVG13 Biphenyl 0.13 0.03 0.04 0.06 0.05 0.05 0.06 0.06 0.05

C1-biphenyl 0.4 0.25 0.54 1.32 0.4 0.14 0.23 0.27 0.13 C2-biphenyl 2.21 1.5 1.75 2.29 1.32 0.76 0.86 1.04 0.83 Naphthalene 0.44 0.09 0.08 0.06 0.09 0.15 0.16 0.18 0.13

C1-naphthalene 0.78 0.14 0.12 0.1 0.15 0.27 0.26 0.32 0.24 C2-naphthalene 0.68 0.14 0.35 1.09 0.39 0.25 0.39 0.33 0.24 C3-naphthalene 3.45 2.83 5.32 9.53 3.04 1.41 1.83 1.83 1.14 a C4-naphthalene 3.19 2.96 3.55 3.85 2.98 2.37 2.29 1.84 1.14 Dibenzothiophene 1.83 1.87 1.88 1.71 1.76 1.54 1.38 1.51 1.2

C1-Dibenzothiophene 1.44 1.54 1.29 1.06 1.45 1.66 1.46 1.34 1.24

C2-Dibenzothiophene 1.73 2.03 1.66 1.24 2.13 2.66 2.53 1.89 2.03 Phenanthrene 31.18 32.22 31.73 25.67 28.2 25.26 21.83 27.78 21.42

C1-phenanthrene 9.1 9.25 8.07 6.19 9.43 11.06 9.84 9.42 9.99

C2-phenanthrene 7.12 7.83 6.56 5.17 8.08 11.31 11.36 8.06 10.51 C3-phenanthrene 3.65 4.04 3.37 4.07 4.01 5.43 6.14 4.16 5.86   C4-phenanthrene 2.31 0.61 0.94 Fluorene 3.36 3.38 4.76 5.95 2.75 1.19 1.5 2.12 1.09

C1-fluorene 2.68 2.3 2.35 2.4 1.99 1.42 1.31 1.83 1.27 C2-fluorene 1.86 2.17 2.06 1.65 2.39 2.43 2.12 2.33 2.09 phenylnaphthalene 0.98 1.07 0.93 0.73 1.28 1.36 1.19 1.42 1.49

C1-phenylnaphthalene 0.53 0.61 0.47 0.37 0.64 0.77 0.82 0.63 0.87 Fluoranthene 7.11 7.84 7.68 5.79 9.52 10.77 10.28 13.19 14.39

C1-fluoranthene 0.12 0.15 0.12 0.14 0.21 0.19 0.25 0.18 0.14 Pyrene 3.42 3.85 3.76 3.13 5.07 4.74 5.16 5.05 5.03

C1-pyrene 0.13 0.16 0.18 0.14 0.22 0.19 0.26 0.21 0.29 C1-pyrene/fluoranthene 0.57 0.61 0.54 0.66 0.94 0.82 0.96 0.78 0.8 Dibenzofuran 0.44 0.43 1.07 1.73 0.7 0.28 0.45 0.46 0.26

C1-dibenzofuran 2.59 2.45 3.01 3.21 2.24 1.38 1.42 2.05 1.61 Benzofluoranthene 1.62 1.09 0.83 1.26 1.06 1.15 1.87 1.1 1.88 Benzo[e]pyrene 0.78 0.63 0.5 1.09 0.57 0.58 1.12 0.85 1.26 Retene 2.25 2.25 1.77 0.92 1.67 2.87 3.32 1.21 2.03 11H-benzo[a]fluorene 0.21 0.23 0.21 0.19 0.28 0.33 0.39 0.35 0.45 11H-benzo[a]fluorene/MethylFluoranthene 0.2 0.29 0.26 0.27 0.35 0.32 0.47 0.35 0.41 Benz[a]anthracene 0.09 0.15 0.12 0.39 0.21 0.08 0.18 0.15 0.32 Chrysene 1.47 1.44 1.14 1.38 1.48 1.64 2.62 2.03 3.16

C1-chrysene 0.49 0.43 0.33 0.82 0.46 0.47 0.86 0.59 0.84 Parent PAHsb 57.07 58.32 58.09 52.12 57.18 54.71 54.35 59.94 57.38 Phenanthrene in tPAHsc 51.05 53.34 49.73 41.1 49.72 53.05 49.18 49.42 47.78 Fluoranthene/pyrene 2.08 2.03 2.04 1.85 1.88 2.27 1.99 2.61 2.86

—: not detect. a: “Cn-PAH” means the PAH alkyl homologs, n = the number of alkyls. e.g., C0-naphthalene: the parent naphthalene; C4-naphthalene: four methyls alkylated naphthalene. b: Parent PAHs in total PAHs(%). c: Phenanthrene and its alkyl homologs in total PAHs(%).

tation from seawater-type fluids enriched in Si and/or Mg thermal fluids (Peng et al., 2011). by interaction with sediments; (b) direct precipitation at Fe elements are significant high in MAR1-2 and hydrothermal vents upon mixing Mg-rich seawater with MAR1-3. Zn and Cu elements were present in all sam- silica-rich hydrothermal fluids; and (c) reactive replace- ples and its concentration in the hydrothermal sediments ment of primary igneous minerals (e.g., olivine and is much higher than the reference sample MAR6-1. The pyroxene) in mafic and ultramafic rocks, or reactive re- enrichment of these heavy metal elements is prevalent in placement of other metamorphic/hydrothermal minerals the hydrothermal sediments, as the hydrothermal fluid (D’Orazio et al., 2004). As the basalt base rock and silica- supplies these elements to the underlying sediments that rich hydrothermal fluids of the Kairei hydrothermal field, are either sourced hydrothermally directly or scavenged the talc formed in CIR7 sediments could be precipitated from seawater via the hydrothermal plume (Cave et al., by the mixing of seawater and silica-rich Kairei hydro- 2002). Combining Ce and Eu depletion REE pattern (Peng

36 J. Li et al. Relative abundance IR7-1 MAR1-1

IR7-2 MAR1-2

IR7-3 MAR1-3

IR7-4 MAR6-1

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 TVG13

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36

Fig. 2. Pattern of PAHs composition in the hydrothermal sediment samples from CIR and MAR. 1. Biphenyl; 2. C1-biphenyl; 3. C2-biphenyl; 4. Naphthalene; 5. C1-naphthalene; 6. C2-naphthalene; 7. C3-naphthalene; 8. C4-naphthalenea; 9. Dibenzothiophene; 10. C1-Dibenzothiophene; 11. C2-Dibenzothiophene; 12. Phenanthrene; 13. C1-phenanthrene; 14. C2-phenanthrene; 15. C3- phenanthrene; 16. C4-phenanthrene; 17. Fluorene; 18. C1-fluorene, 19. C2-fluorene, 20. phenylnaphthalene; 21. C1- phenylnaphthalene; 22. Fluoranthene; 23. C1-fluoranthene; 24. Pyrene; 25. C1-pyrene; 26. C1-pyrene/fluoranthene; 27. Dibenzofuran; 28. C1-dibenzofuran; 29. Benzofluoranthene; 30. Benzo[e]pyrene; 31. Retene; 32. 11H-benzo[a]fluorine; 33. 11H-benzo[a]fluorene/MethylFluoranthene; 34. Benz[a]anthracene; 35. Chrysene; 36. C1-chrysene.

Characteristics and source of polycyclic aromatic hydrocarbons in the hydrothermal sediments 37 Fig. 3. Representative total ion current profile from hydrothermal sediment sample CIR7-1. Numbers refer to compound peak. 1: naphthalene; 2: dibenzofuran; 3: fluorine; 4: methyldibenzofuran; 5: 1,3,6,7-tetramethylnaphthalene; 6: dibenzothiophene; 7: phenanthrene; 8: 3-methylphenanthrene; 9: 9-methylphenanthrene; 10: 1-methylphenanthrene; 11: 2-phenylnaphthalene; 12: 2,10-dimethylphenanthrene; 13: fluoranthene; 14: pyrene; 15: trimethylphenanthrene; 16: retene; 17: benz[a]anthracene; 18: chrysene; 19: benzofluoranthene; 20: benzo[e]pyrene.

et al., 2011), the presence of Fe-oxyhydroxides suggest tures у389.8°C (Bischoff, 1991). Under such a high tem- that MAR1 samples might be from an environment of perature condition, the PAHs are formed as a result of plume fall-out, where hydrothermal components are synthesis and polycondensation of simple carbon contain- strongly diluted by pelagic sediments. ing compounds (Chernova et al., 1999). After that, the Ca element is detected in high amounts in the sam- metal elements and PAHs rich hydrothermal fluid is buoy- ples TVG13, MAR1-1 and MAR6-1, but it is from a dif- ant and rapidly ascends through ocean crust upflow zones ferent source between TVG13 and the two MAR sam- and is vented into the overlying seawater (e.g., Lupton, ples. In sample TVG13, Ca (and S) element is sourced 1995). from anhydrite, which is typical mineral in the exterior Here, together with the high content of metal elements, wall of a sulfide chimney. In MAR1-1 and MAR6-1, the the presence of PAHs in these hydrothermal sediments of presence of Ca element is related to the occurrence of this study reflected their rapid high temperature genesis calcite, which is from a normal pelagic sedimentary en- during the hydrothermal process in the marine hydrother- vironment. mal systems (Simoneit, 1984; Kawka and Simoneit, 1990; Simoneit and Fetzer, 1996). Parent PAHs and their The characteristics and source of polycyclic aromatic alkylated homolog are both detected and the Parent PAHs hydrocarbons in the hydrothermal sediments presenting in a high proportion showed a different char- Circulation of the seawater downward through the acteristic in this hydrothermal bitumen when compared ocean crust results in high-temperature chemical reactions to the crude oils, because the parent PAHs are rather un- between seawater and rocks. These heated fluids cause common in crude oils but ubiquitous in high temperature intensive leaching of host rock and generate a modified pyrolysates (Venkatesan et al., 2003). In addition, that high-temperature fluid enriched in some heavy metal el- the LMW PAHs were in a high proportion and the HMW ements (e.g., Fe, Mn, Cu, Zn, Si) in the high temperature PAHs (>6 rings) were absent were another two major char- “reaction zones”, where the critical point of hydrother- acteristics of the hydrothermal bitumens in present study. mal fluids would be reached and phase separated would This result is similar to the analysis of the bottom be happened (German and Von Damm, 2004). To phase sediments at the Central Indian Basin–deformation zone separate seawater at typical intermediate-to-fast spread- (Chernova et al., 1999, 2001; Venkatesan et al., 2003), ing Mid-ocean ridge, depths of 2500 m requires tempera- but contrast to those of the hydrothermal deposits

38 J. Li et al. 5rings 4rings 3rings 2rings 100%

90%

80%

70%

60%

50%

40%

30%

20%

10%

0% CIR7-1 CIR7-2 CIR7-3 CIR7-4 MAR1-1 MAR1-2 MAR1-3 MAR6-1 TVG13 Sample Fig. 4. Percentage of aromatic rings in PAHs in the hydrothermal sediment from CIR and MAR (2-rings PAHs include naphthalene, biphenyl; 3-rings PAHs include dibenzothiophene, dibenzofuran, phenanthrene, fluorene, phenylnaphthalene; 4-rings PAHs include fluoranthene, retene, pyrene, benzo[a]fluorene, benz[a]anthracene and chrysene; 5-rings PAHs include benzofluoranthene, benzo[e]pyrene).

(Simoneit et al., 2004) and chimney samples (Simoneit (Baumard et al., 1999; Serafim et al., 2008). In current and Fetzer, 1996). Similar to the explanation in Simoneit study, the ratio of F/P for all these samples suggested these et al. (2004), this difference is case of the LMW PAHs PAHs were from a pyrolytic products source. Moreover, have a greater solubility than the high molecular weight the presence of PAH analogs with 5-membered aromatic PAHs (Kawka and Simoneit, 1990), which led to the lower ring (e.g., benzopyrenes) further supported this conclu- components removed from the interior of the hydrother- sion (Blumer, 1976; Youngblood and Blumer, 1975). As mal system to the around sediments, then mixed with the the BaP is less stable than BeP in the oxidative atmos- endogenous organic matters. pheric environment (Nielsen, 1984), the ratio of BaP/BeP The distribution of phenanthrene and its alkyl have been used to gauge the extent of secondary oxida- homologs, which were the most dominant abundant suite tion of the PAHs once formed (Rushdi and Simoneit, of PAHs in this study, and some other PAH homologs (e.g., 2002). In this study, the absence of BaP could indicate fluoranthene and fluorene) in the present samples sug- that all of these samples experienced a severely oxida- gested that not much biodegradation had occurred, be- tion process or thermal loss at the surface sediments en- cause biodegradation would preferentially remove the vironments. The oxidation process would result in the parent and monosubstituted triaromatics (Rowland et al., LMW analogs loss as such kind of weathering would pref- 1986; Venkatesan et al., 2003). Therefore, primary and erentially degrade the LMW PAHs (Marynnowski et al., secondary migrations occurred as a rapid process and bio- 2011). However, the LMW compounds still were the degradation was thus assumed to have no significant ef- dominant components in these hydrothermal sediments. fect due to limited contact time between the microorgan- This phenomenon could be clarified by the following two isms and PAHs (Rushdi and Simoneit, 2002). This LMW explanations. First, BaP might be more sensitive to the PAHs profiles in our samples were also similar to those oxidation process than the LMW PAHs at the marine en- of the Andaman sediments, which suggested that the hy- vironments. Second, the thermal loss might play a larger drothermal petroleum have undergone probably a limited role in the decrease of BaP in the hydrothermal environ- post-depositional alteration (Venkatesan et al., 2003). ments, however its effects on the degradation of the LMW Fluoranthene and pyrene are often considered as typi- PAHs is not obvious. cal pyrogenic products generated from high temperature Retene, biomarker mostly associated with the condensation of LMW compounds (Serafim et al., 2008). diagenesis of vascular plant resins and conifer combus- Pyrolytic products are usually characterized by a predomi- tion products (Simoneit, 1986), was also observed in all nance of fluoranthene over pyrene (F/P ratio > 1) these samples. Generally, retene has been considered to

Characteristics and source of polycyclic aromatic hydrocarbons in the hydrothermal sediments 39 Rescaled Distance Cluster Combine 0 5 1015 20 25 Label

CIR7-1 Group I CIR7-2 CIR7-3 MAR1-1 Group II MAR6-1 MAR1-2 Group III MAR1-3 TVG13 Group IV CIR7-4

Fig. 5. HCA cluster diagram of PAH data.

be derived from a diagenetic product of abietic acid, a common diterpenoid acid in conifer resins (Laflamme and Hites, 1978). However, abundant retene was also reported in a Chinese Precambrian and Lower Palaeozoic carbonate formation where there was presumed to be no higher plant input (Jiang et al., 1995; Zhou et al., 2000) and so potential microbial sources need to be kept in mind in Fig. 6. CCA ordination diagram of PAH concentrations with interpretation (Jiang et al., 1998). In this study, although inorganic major element factors as arrows. these hydrothermal sediments were collected from areas far from the land, we are apt to consider them as a biomarker for the terrestrial high plant source. This con- The close relationship between MAR1-1 and MAR6-1 in clusion was supported by the analysis of the aliphatic Cluster II was consistent with the elements and mineral components in these samples (Peng et al., 2011). Firstly, data, which suggested that both of the two samples had a the resolved n-alkanes in the MAR samples distributed significant amounts of calcite. This result could indicate in bimodal patterns, a small second mode between n-C25 that the two samples were influenced more by the normal and n-C38 (maximum C29 or C31) was been observed and marine sediment environments. The cluster III included the OEP31 (C27~C36) ranges from 2.42 to 2.85 in the two samples which have high content of Fe elements and MAR1 sediments (Peng et al., 2011). Secondly, the δ13C one sample from a fragment of hydrothermal chimney values of the n-alkanes and isoprenoid hydrocarbons (Pr wall. All of the three samples were more close to the hy- and Ph) are in the range –33.1‰ to –26.91‰ (vs. PDB) drothermal environments. in these samples, and they are comparable to the n-alkanes In our previous study (Peng et al., 2011), based on the from Holes 858A and 858C from ODP139 in the middle elements and mineralogical data we considered the CIR7 valley of the northeastern Pacific Ocean, which are typi- samples originated from an environment where the silica- cal of isotopic ratios for terrestrial organic matter mixed rich hydrothermal fluids mixing with the Mg-rich with some marine organic matter (Simoneit, 2002). There- seawater, and the MAR sediments were associated with fore, the presence of retene and analysis of aliphatic frac- pelagic carbonate oozes containing some precipitates de- tion, both of them suggested that there was a terrestrial rived from hydrothermal plume fall-out. As a whole of organic inputs in the two Ocean Ridge hydrothermal en- the hydrothermal system, it is expected that the distribu- vironments. tion of various inorganic matters are correlated to the changes of various types of organic matter. CCA analysis Multivariable statistics analysis could supply the chance to find the inherent relationship HCA is a suitable tool for differentiating samples in between the inorganic major elements and PAHs in the relation to sampling sites. As the result shows, members hydrothermal sediments. As the results of CCA analysis, of cluster I and cluster IV were sediments sampled from Si, Mg, S, Ca elements emerged as significant factors the same TVG and had a similar major elements pattern. which influenced the distribution of the PAHs in this However, their PAHs composition divided them into two study, and followed by Fe and Zn elements. The presence different groups. This result further confirmed the com- of biphenyl and fluorene homologues was speculated from plexity of the hydrothermal system, even in a small sam- a source of volcanic matter in some other previous stud- ple site area, the composition of PAHs could be different. ies (Chernova et al., 2001). However, from the above CCA

40 J. Li et al. analysis, we propose that these LMW PAHs were more thermal field. LMW PAHs would vent out by dissolving related to the Talc formation environment (Si and Mg el- in the hydrothermal fluids, while the heavier analogs ements), where the process of the Si-rich hydrothermal would be deposited in the chimney inside wall. fluids mixed with the Mg-rich seawater (Peng et al., 2011). The IMW analogs (3 rings and 4 rings, e.g., phen- Acknowledgments—We thank two anonymous reviewers and anthrene, dibenzothiophene and retene) were the most the associate editor Dr. Ken Sawada for helpful comments and significant components in these hydrothermal sediments suggestions to improve this manuscript. Special thanks also go samples. Based on the CCA analysis, these IMW PAHs to all the participants of the cruise of R/V DA YANG YI HAO have a positively relation with the metal elements (Fe, conducted by China Ocean Mineral Resource R&D Associa- tion (COMRA) in 2005. This research was supported by the Cu and Zn), which are mainly related to the Fe- National Natural Science Foundation of China (Grant No. oxyhydroxide and sulfide mineral in this hydrothermal 41172309) and the National Basic Research Program of China environment. This result indicated that IMW PAHs and (Grant No. 2012CB417300). the metal elements would have a similar origin, which were probably formed in the high temperature environment and subsequently vented out by partly dissolving in REFERENCES the hydrothermal fluid or adsorbing on the mineral parti- Batuev, B. N., Krotov, A. G. and Markov, V. F. (1994) Massive cles. The distribution of HMW PAHs (4 rings and 5 rings) sulfide deposits discovered at 14°45′ N, Mid-Atlantic Ridge. showed a primarily positive correlation with S and Ca BRIDGE Newsletter 6, 6–10. elements. Although there were also a high concentration Baumard, P., Budzinski, H., Garrigues, P., Dizer, H. and Hansen, of Ca in the normal marine sediments (MAR1-1 and P. D. (1999) Polycyclic aromatic hydrocarbons in recent MAR6-1), S and Ca elements were simultaneously present sediments and mussels (Mytilus edulis) from the Western in a high content only occurred in the fragment chimney Baltic Sea: occurrence, bioavailability and seasonal varia- wall (TVG13). Therefore, we could conclude that the tions. Mar. Environ. Res. 47, 17–47. Bischoff, J. L. (1991) Densities of liquids and vapors in boil- HMW PAHs were closely related to the exterior of chim- ° ing NaCl–H2O solutions: a PVTX summary from 300 C to ney (S and Ca elements). As the absence of the heavy 500°C. Am. J. Sci. 291, 309–338. PAHs (>5 rings) in this study, and combined with previ- Blumer, M. (1976) Polycyclic aromatic hydrocarbons in nature. ous studies (Simonet et al., 2004), we suggested that the Sci. Am. 234, 35–43. heavy components would stay in the interior of sulfide Budzinski, H., Jones, I., Bellocq, J., Piérard, C. and Garrigues, chimney (e.g., >5 rings) or exterior of the chimney wall P. (1997) Evaluation of sediment contamination by polycy- (4 rings and 5 rings) as their relative low solubility. clic aromatic hydrocarbons in the Gironde estuary. Mar. Chem. 58, 85–97. Cannat, M., Lagabrielle, Y., Bougault, H., Casey, J., De CONCLUSION Coutures, N., Dmitriev, L. and Fouquet, Y. (1997) Surface hydrothermal sediments collected from the Ultramafic and gabbroic exposures at the Mid-Atlantic Ridge: geological mapping in the 15°N region. Kairei hydrothermal field of the CIR and Logatchev hy- Tectonophysics 279, 193–213. drothermal field of MAR were analyzed for PAHs and Cave, R. R., German, C. R., Thomson, J. and Nesbitt, R. W. major elements concentration. The PAHs relative abun- (2002) Fluxes to sediments underlying the Rainbow hydro- dance data showed a much higher proportion of LMW thermal plume at 36°14′ N on the Mid-Atlantic Ridge. PAHs and the fluoranthene/pyrene ratio combined with Geochim. Cosmochim. Acta 66, 1905–1923. the presence of 5-membered alicyclic ring indicated all Chernova, T. G., Paropkari, A. L., Pikovskii, Yu. I. and the PAHs that recovered using our method had a pyrolytic Alekseeva, T. A. (1999) Hydrocarbons in the Bay of Ben- origin. In addition, the LMW PAHs profile suggested these gal and Central Indian Basin bottom sediments, indicators samples had experienced a severe oxidization process or of geochemical processes in the lithosphere. Mar. Chem. thermal loss but less biodegradation occurred. The emerg- 66, 231–243. ing pattern of PAHs in these surface hydrothermal Chernova, T. G., Rao, P. S., Pikovskii, Yu. I., Alekseeva, T. A., Nath, B. N., Rao, B. R. and Rao, C. M. (2001) The compo- sediments could be due to the high solubility of the smaller sition and the source of hydrocarbons in sediments taken PAHs in hot fluid and their consequent removal from in- from the tectonically active Andaman Backarc Basin, In- terior of the hydrothermal system to outside and mixed dian Ocean. Mar. Chem. 75, 1–15. with in situ organic matters around sediments. The pres- Dang, H., Zhang, X., Sun, J., Li, T., Zhang, Z. and Yang, G. ence of retene in these hydrothermal sediments indicated (2008) Diversity and spatial distribution of sediment that a source of terrestrial input should not be ignored. ammonia-oxidizing crenarchaeota in response to estuarine On the base of HCA and CCA analyses, we suggested and environmental gradients in the Changjiang Estuary and that the different molecular weight PAHs would occur in East China Sea. Microbiology 154, 2084–2095. different hydrothermal structures within a given hydro- Delacour, A., Früh-Green, G. L., Bernasconi, S. M., Schaeffer,

Characteristics and source of polycyclic aromatic hydrocarbons in the hydrothermal sediments 41 P. and Kelley, D. S. (2008) Carbon geochemistry of tion of polycyclic aromatic hydrocarbons in recent serpentinites in the Lost City Hydrothermal System (30°N, sediments. Geochim. Cosmochim. Acta 42, 289–303. MAR). Geochim. Cosmochim. Acta 72, 3681–3702. Lupton, J. E. (1995) Hydrothermal plumes: near and far field. D’Orazio, M., Boschi, C. and Brunelli, D. (2004) Talc-rich Seafloor Hydrothermal Systems: Physical, Chemical, Bio- hydrothermal rocks from the St. Paul and Conrad fracture logical, and Seological Interactions (Humphris, S., zones in the Atlantic Ocean. Eur. J. Mineral. 16, 73–83. Zierenberg, R., Mullineaux, L. and Thomson, R., eds.), 317– Gamo, T., Chiba, H., Yamanaka, T., Okudaira, T., Hashimoto, 346, Geophysical Monograph 91, AGU, Washington, D.C. J., Tsuchida, S., Ishibashi, J., Kataoka, S., Tsunogai, U., Marynnowski, L., Kurkiewicz, S., Rakocinski, M. and Simoneit, Okamura, K., Sano, Y. and Shinjo, R. (2001) Chemical char- B. R. T. (2011) Effects of weathering on organic matter: I. acteristics of newly discovered black smoker fluids and as- Changes in molecular composition of extractable organic sociated hydrothermal plumes at the Rodriguez Triple Junc- compounds caused by paleoweathering of a Lower Carbon- tion, Central Indian Ridge. Earth Planet Sci. Lett. 193, 371– iferous (Tournaisian) marine black shale. Chem. Geol. 285, 379. 144–156. Gallant, R. M. and Von Damm, K. L. (2006) Geochemical con- Michaelis, W., Jenisch, A. and Richnow, H. H. (1990) ‘Hydro- trols on hydrothermal fluids from the Kairei and Edmond thermal Petroleum Generation in Red Sea Sediments from Vent Fields, 23°–25°S, Central IR. Geochem. Geophys. the Kebrit and Shaban Deeps’, in Organic Matter Altera- Geosyst. 7, Q06018, doi:10.1029/2005GC_001067. tion in Hydrothermal Systems-Petroleum Generation, Mi- Gennadiyev, A. N., Pikovskii, Yu. I. and Florovskaya, V. N. gration and Biogeochemistry, Simoneit, B. R. T. (ed.). Appl. (1996) Geochemistry of Polycyclic Aromatic Hydrocarbons Geochem. 5, 103–114. in Rocks and Soils. Moscow Univ. Publ., Moscow, 192 pp. Nielsen, T. (1984) Reactivity of polycyclic hydrocarbons to- (in Russian). ward nitrating species. Environ. Sci. Technol. 18, 157–163. German, C. R. and Von Damm, K. L. (2004) Hydrothermal proc- Peng, X., Li, J., Zhou, H., Wu, Z., Li, J., Chen, S. and Yao, H. esses. Treatise on Geochemistry 6 (Holland, H. D., Turekian, (2011) Characteristics and source of inorganic and organic K. K. and Elderfield, H., eds.), 181–222, The Oceans and compounds in the sediments from two hydrothermal fields Marine Geochemistry, Oxford, U.K., Elsevier-Pergamon. of the Central Indian and Mid-Atlantic ridges. J. Asian Earth Hashimoto, J., Ohta, S., Gamo, T., Chiba, H., Yamaguchi, T., Sci. 41, 355–368. Tsuchida, S., Okudaira, T., Watabe, H., Yamanaka, T. and Pikovskii, Yu. I., Chernova, T. G., Alekseeva, T. A. and Kozin, Kitazawa, M. (2001) First hydrothermal vent communities I. S. (1996) New data on the composition of polycyclic aro- from the Indian Ocean discovered. Zool. Sci. 18, 717–721. matic hydrocarbons in sulfides and bottom sediments of the Herzig, P. and Plüger, W. (1988) Exploration for hydrothermal Guaymas Basin, Gulf of California. Geochem. Int. 34, 408– activity near the Rodriguez Tripile junction, Indian Ocean. 415. Can. Mineral. 26, 721–736. Rowland, S. J., Alexander, R., Kagi, R. I., Jones, D. M. and Jiang, C., Alexander, R., Kagi, R. I. and Murray, A. P. (1998) Douglas, A. G. (1986) Microbial degradation of aromatic Polycyclic aromatic hydrocarbons in ancient sediments and components of crude oils: a comparison of laboratory and their relationships to palaeoclimate. Org. Geochem. 29, field observations. Org. Geochem. 9, 153–161. 1721–1735. Rudenko, A. P. and Kulakova, I. I. (1986) A physicochemical Jiang, N., Tong, Z., Ren, D., Song, F., Yang, D., Zhu, C. and model of abiogenic synthesis of hydrocarbons in natural Gao, Y. (1995) The discovery of retene in Precambrian and conditions. Mendeleev Chem. J. 31, 56–69. Lower Paleozoic marine formations. Chin. J. Geochem. 14, Rushdi, A. I. and Simoneit, B. R. T. (2002) Hydrothermal al- 41–51. teration of organic matter in sediments of the Northeastern Kawka, O. E. and Simoneit, B. R. T. (1990) Polycyclic aro- Pacific Ocean: Part 1. Middle Valley, Juan de Fuca Ridge. matic hydrocarbons in hydrothermal petroleums from the Appl. Geochem. 17, 1467–1494. Guaymas Basin spreading center. Appl. Geochem. 5, 17– Serafim, A., Lopes, B., Company, R., Ferreira, A. M. and 27. Bebianno, M. J. (2008) Comparative petroleum hydrocar- Konn, C., Charlou, J. L., Donval, J. P., Holm, N. G., Dehairs, bons levels and biochemical responses in mussels from hy- F. and Bouillon, S. (2009) Hydrocarbons and oxidized or- drothermal vents (Bathymodiolus azoricus) and coastal en- ganic compounds in hydrothermal fluids from Rainbow and vironments (Mytilus galloprovincialis). Mar. Pollut. Bull. Lost City ultramafic-hosted vents. Chem. Geol. 258, 299– 57, 529–537. 314. Simoneit, B. R. T. (1984) Hydrothermal effects on organic Konn, C., Testemale, D., Querellou, J., Holm, N. G. and matter-high vs. low temperature components. Org. Charlou, J. L. (2011) New insight into the contributions of Geochem. 6, 857–864. thermogenic processes and biogenic sources to the genera- Simoneit, B. R. T. (1986) Organic matter alteration and petro- tion of organic compounds in hydrothermal fluids. leum generation: Hydrothermal aspect. Geochimiya 11, 236– Geobiology 9, 79–93. 254. Kvenvolden, K. A., Rapp, J. B., Hostettler, F. D., Morton, J. L., Simoneit, B. R. T. (1993) Aqueous high-temperature and high King, J. D. and Claypool, G. E. (1986) Petroleum associ- pressure organic geochemistry of hydrothermal vent sys- ated with polymetallic sulfide in sediment from Gorda tems. Geochim. Cosmochim. Acta 57, 3231–3243. Ridge. Science 234, 1231–1234. Simoneit, B. R. T. (1994) Lipid/bitumen maturation by hydro- Laflamme, R. E. and Hites, R. A. (1978) The global distribu- thermal activity in sediments of Middle Valley, Leg 139.

42 J. Li et al. Proc. ODP, Sci. Results, 139 (Mottl, M., Davis, E., Fisher, leum and associated lipids in the sulfide deposits of the A. and Slack, J., eds.), 447–465, Ocean Drilling Program. Rainbow Field (Mid-Atlantic Ridge at 36°N). Geochim. Simoneit, B. R. T. (1995) Evidence for organic synthesis in high Cosmochim. Acta 68, 2275–2294. temperature aqueous media-facts and prognosis. Origins ter Braak, C. J. F. (1986) Canonical correspondence analysis: a Life Evol. Biosphere 25, 119–140. new eigenvector technique for multivariate direct gradient Simoneit, B. R. T. (2002) Carbon isotope systematic of indi- analysis. Ecology 67, 1167–1179. vidual hydrocarbons in hydrothermal petroleum from Mid- Van Dover, C. L., Humphris, S. E., Fornari, D., Cavanaugh, C. dle Valley, Northeastern Pacific Ocean. Appl. Geochem. 17, M., Collier, R., Goffredi, S. K., Hashimoto, J., Lilley, M. 1429–1433. D., Reysenbach, A. L., Shank, T. M., Von Damm, K. L., Simoneit, B. R. T. and Fetzer, J. C. (1996) High molecular Banta, A., Gallant, R. M., Gotz, D., Geen, D., Hall, J., weight polycyclic aromatic hydrocarbons in hydrothermal Harmer, T. L., Hurtado, L. A., Johnson, P., McKiness, Z. P. petroleums from the Gulf of California and Northeast Pa- and Meredi, C. (2001) Biogeography and ecological set- cific Ocean. Org. Geochem. 24, 1065–1077. ting of Indian Ocean hydrothermal vents. Science 294, 818– Simoneit, B. R. T. and Lonsdale, P. F. (1982) Hydrothermal 823. petroleum in mineralized mounds at the seabed of Guaymas Venkatesan, M. I., Ruth, E., Rao, P. S., Nath, B. N. and Rao, B. Basin. Nature 295, 300–303. R. (2003) Hydrothermal petroleum in the sediments of the Simoneit, B. R. T., Mazurek, M. A., Brenner, S., Crisp, P. T. Andaman Backarc Basin, Indian Ocean. Appl. Geochem. 18, and Kaplan, I. R. (1979) Organic geochemistry of recent 845–861. sediments from Guaymas Basin, Gulf of California. Deep- Youngblood, W. W. and Blumer, M. (1975) Polycyclic aromatic Sea Res. 26A, 879–891. hydrocarbons in the environment: homologues series in soils Simoneit, B. R. T., Grimalt, J. O., Hayes, J. M. and Hartman, and recent marine sediments. Geochim. Cosmochim. Acta H. (1987) Low Temperature Hydrothermal Maturation of 39, 1303–1314. Organic Matter in Sediments from the Atlantis II Deep, Red Zhou, W., Wang, R. Y. and Wu, Q. Y. (2000) Retene in Sea. Geochim. Cosmochim. Acta 51, 879–894. pyrolysates of algal and bacterial organic matter. Org. Simoneit, B. R. T., Alla, Y. L., Ptersypkin, V. I. and Osipov, G. Geochem. 31, 757–762. A. (2004) Composition and origin of hydrothermal petro-

Characteristics and source of polycyclic aromatic hydrocarbons in the hydrothermal sediments 43