ISSN 00978078, Water Resources, 2013, Vol. 40, No. 3, pp. 285–296. © Pleiades Publishing, Ltd., 2013. Original Russian Text © N.S. Safronova, E.S. Grishantseva, G.S. Korobeinik, 2013, published in Vodnye Resursy, 2013, Vol. 40, No. 3, pp. 274–286. WATER QUALITY AND PROTECTION: ENVIRONMENTAL ASPECTS

Hydrocarbon Gases (C1–C5) and Organic Matter in Bottom Sediments of the Ivankovo Reservoir on the River N. S. Safronovaa, E. S. Grishantsevaa, and G. S. Korobeinikb a Moscow State University, Moscow, 119991 Email: [email protected] b Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, ul. Kosygina 19, GSP1, Moscow, 119991 Russia Received June 21, 2011

Abstract—The results of studying the composition of hydrocarbon gases (C1–C5) and organic matter in bot tom sediments of the Ivankovo Reservoir in 1995, 2004, and 2005 are given. The methods used in the study include vaporphase gas chromatography, instrumental pyrolysis gas chromatography, and massspectrom 13 etry for determining organic carbon δ Corg. The gas field of bottom sediments in different regions of the res ervoir varies widely in terms of gas saturation and the spectrum of hydrocarbon gases. This suggests the het erogeneous composition of organic matter in the sediments and different conditions of its input and transfor mation processes. The gases were found to contain saturated hydrocarbons from methane to pentane C1–C5, including isomers iC4 and iC5 and unsaturated compounds C2–C4. A correlation was found to exist between methane distribution and the distribution of its more highmolecular homologues, which confirms their genetic relationship in bottom sediments. The obtained results show an increase in the rate of microbi ological processes and organic matter transformation for most regions in the Ivankovo Reservoir. The only exceptions are the zones of Moshkovichskii Bay and the sections at Gorodnya and Konakovo, where tech nogenic organic matter is being accumulated. The high information value of hydrocarbon gases as bio geochemical markers of the sources of organic matter and the rates of its transformation is demonstrated. The isotopic composition of organicmatter carbon in the bottom sediments of the Ivankovo Reservoir δ 13C var ies from –26.1 to –30.86‰.

Keywords: bottom sediments, organic matter, gas hydrocarbons, vaporphase gas chromatography, pyrolysis gas chromatography, mass spectrometry DOI: 10.1134/S0097807813020085

INTRODUCTION the end hydrocarbon product of OM mineralization, and can serve as an indicator of those processes. How The role of bottom sediments (BS) in the life of a ever, the concentration of methane, especially in top water body is extremely high. The composition and sampling horizons, can demonstrate the effect of both properties of BS reflect the totality of biological, methanogenesis processes and the properties of meth chemical, and physical processes taking place in the ane as a very mobile gas with low sorption capacity and water body. The rates of biochemical processes of comparatively low water solubility. Because of this, the organic matter (OM) transformation are evaluated by geochemical data on methane distribution in BS a wide range of characteristics. The reduction of low should be studied along with other gas characteristics. molecular OM in BS of freshwater bodies is accompa nied by the production of the majority of methane and Studies show that the distribution of gaseous other lowmolecular hydrocarbons, whose concentra hydrocarbons (HC) in natural features is a function of tions can be used to evaluate the ecological state of the original OM and its transformation processes. The water body [4, 5, 8–10, 13, 14]. The accumulation of specific features of the distribution of gaseous HC can gases in BS depends on OM composition and concen be used as typical organic–geochemical characteris tration. Informative biogeochemical markers of OM tics [7, 12]. sources and its transformation processes are gaseous To collect information about the sources of matter hydrocarbons. Gasometry methods are in wide use in containing compounds of natural and anthropogenic geochemical studies [2, 3, 11, 18]. The total rate of OM, the following tasks were formulated: OM biodegradation processes is mostly assessed by the measured methane content, because methane forms to determine the concentrations of hydrocarbon and occurs in the biosphere almost ubiquitously; it is gases (С1–С5) and to consider the regularities in their

285 286 SAFRONOVA et al.

N

Ivan’kovskii Pool Peretrusovskii Bay Soz R. 8 Omuntinskii Bay 10 Volzskii Babninskii Bay Peremerki Cr. Pool 9 Moshkovicheskii Bay 12 7 ГРЭС 13 Vidogoshchi 6 Konakovo 1 2 3 Donkhovka R. Melkovo Ploski Redkino 4 14 11

5 Gorodishche Shoshinskii Pool Novozavidovskii

Fig. 1. BS sampling scheme in the Ivankovo Reservoir. Sections: (1) Gorodnya, (2) Melkovo, (3) NizovkaVolga, (4) Nizovka , (5) Gorodishche, (6) Ploski, (7) Konakovo, (8) Korcheva, (9) Klintsy, (10) Dubna. Bays: (11) Vesna, (12) Fedorovskii, (13) Korovinskii; (14) Redkinskii Canal. distribution in the top BS layers of the Ivankovo Res generalized characteristics of OM have recently ervoir; gained in popularity in geochemical studies [6, 16, 19]. to determine the concentration of total OM com Vaporphase gas chromatography and instrumental ponents; pyrolysis gas chromatography is used for comprehen to study the isotopic composition of organic carbon sive study of the composition of OM in BS. Mass spec 13 Corg for BS. trometry was used to study the distribution of isotopes 13 of organic carbon δ Corg. METHODS OF STUDIES Gas Chromatography The object of study was the BS of the Ivankovo Res ervoir, for which very few data are available in the lit Gases in BS were studied by vaporphase chroma erature about the concentration and distribution of tography. The analytical procedure included the lowmolecular HC [11, 15]. Field studies were carried extraction of gases from BS by equilibrium vapor out in 1995, 2004, and 2005. The sampling was carried method under static conditions and the subsequent out at 13 sections and in 7 bays from Tver City to determination of the composition and concentration Dubna Town (Fig. 1). of components on gas chromatography [18]. The multicomponent analysis of the composition To extract gases from BS, 1 g of sample material of gaseous and solid phases of BS was carried out for was placed in 15ml glass flasks, distilled water was sediment samples taken in summer by GOIN tube added to 2/3 of flask volume, and the flasks were sealed from the upper horizon of BS (top 10–15 cm) in by selfsealing rubber plugs. After shaking, the flasks points in areas subject to different level of technogenic were placed in a thermostat and exposed at 70°С for impact. 30 min. Next, 1 ml of gas was taken and placed in the OM composition is very diverse. Because of this, flow of carrier gas in “Tsvet500" gas chromatograph the analytical methods for the separation and determi with a flameionization detector (Russia). Analysis of nation of individual compounds and OM classes are methane and other light HC was carried out on "Tsvet very complicated and, sometimes, practically unreal 500" gas chromatograph with a flameionization izable. The most widespread modern method for detector. HC were separated in a packed column with effective separation and analysis of complex multi modified aluminum oxide under isothermal regime of component organic mixture is chromatography [1, 2, column thermostat operation. The optimal conditions 17, 18]. Rapid instrumental methods for determining for the separation and quantitative determination of

WATER RESOURCES Vol. 40 No. 3 2013 HYDROCARBON GASES (C1–C5) AND ORGANIC MATTER 287 hydrocarbon components in gas phase were found The mass of the sample under study was 5–100 mg. [18]. Under optimal operation conditions of RE 2 analyzer Analysis procedure enable determining hydrocar in the specified pyrolysis cycle, the relative standard bons of the series С1–С5 with saturated, unsaturated, deviation for the characteristics to be evaluated varies and isomeric structure: СН4, С2Н6, С2Н4, С3Н8, from 1 to 8%. The lower concentration detection lim С3Н6, iС4Н10, С4Н10, С4Н8, ∑С5Н12 (the sum of its are 0.01–0.03 mg/g. pentanes and isopentanes). The quantitative analysis was made by absolute calibration method. The lower boundaries of the concentrations determined by the Method for Determining the Isotopic Composition of Corg method were 0.001–0.01 μL/kg, depending on the δ13 compound being analyzed. The relative standard devi The isotopic analysis of Corg was carried out on ation varies from 2 to 6% depending on the concentra mass spectrometers Delta S and Delta Plus. The sedi tion and mass of HC. ment samples were first crushed in a ball mill Reatsch HM 200. Carbonates were removed by 10% HCl solu tion. The samples were washed and dried at 60°С. A Pyrolysis Method of OM Studying weighed portion of the sample was used to determine The method of pyrolysis gas chromatography is in the isotopic composition with the use of a CHNsys wide use for obtaining rapid and adequate information tem of mass spectrometer. The instrumental accuracy about the qualitative composition and the amount of was ±0.1%. The reproducibility of the entire cycle, OM in ecological–geochemical objects. including sample preparation, is not higher than ±0.3‰ PDB [2, 3]. The method is highly sensitive and rapid; it enables one to treat small samples by standard equipment. Of wide use now are pyrolysis methods developed for DISCUSSION OF RESULTS automatic analyzers of ROCKEVAL type and operat ing in fully automated regime—from loading the sam The major sources of anthropogenic impact onto ples to the output of data on the concentration of com the reservoir are the industrial plants of the towns of ponents and the evaluated characteristics in the form Tver and Konakovo and the settlements of Redkino of tables and plots [6, 16, 19]. and Melkovo; motor and railway transport; the dis Used in this study was automated ROCKEVAL charges of municipal and domestic wastewaters; agri 2/TOC analyzer (FIN and BEICIPFRANLAB, culture and recreation. France) [16], coupled with a personal computer with software packages ROCKDAT AND ROCKINT and The results of gas chromatography studies of the used to control the process of pyrolysis and to calcu gas phase of BS over the periods of expedition studies late the primary data and carry out their processing. (1995, 2004, 2005) are given in Table 1. The gas field of BS varies widely in different parts of the reservoir in BS taken in the reservoir were predried at the terms of both the level of gas saturation (a quantitative room temperature, blended, and powdered. Under characteristic) and the spectrum of gases (a qualitative programmed heating of the sample (25°C/min) from characteristic). This suggests the heterogeneity of OM 300 to 600°С in a flow reactor in an inert helium composition in the sediments and the difference atmosphere, RE2 analyzer makes it possible to deter between its input conditions in different sampling mine the following OM characteristics: points. The heterogeneous character of OM deter S1—the amount of free HC (С1–С10) that are con mines the different resistance of its components to tained in the sample and that release at 300°С; decomposition and the different contributions of the S2—the amount of highmolecular HC and OM forming gaseous HC into the total composition of BS cracking HC (С12–С36) that release within tempera gas phase. Saturated HC from methane to pentane are ture interval of 300–600°С; identified in the gases: С1–С5, including isomers i S3—the amount of СО2 that forms at the decom С4–iС5, and unsaturated compounds С2–С4.. position of OM or OM cracking within temperature interval 300–400°С, which serves as an indicator of Methane is a dominating component among the the presence of oxygen structures in OM molecules; saturated HC; it was recorded in all examined samples with a share in the total concentration of gases С1–С5 TOC—total Corg concentration in the samples (СН4/ΣС1 – С5 satur) varying from 75 to 99%. Studies evaluated by hydrocarbon parameters; [7, 12] have shown that methane homologs—HC T —pyrolysis furnace temperature at which HC max fractions С2–С3 can form because of biochemical output in the peak of S2 is maximal (peak crest); transformation of terrigenous OM of freshwater river HI—hydrogen index, HI = S2/TOC, which is used basins, such as the ecosystem of the Ivankovo Reser as a characteristic of the presence of hydrogen struc voir. The genesis of HC fraction С4–С5 can be due to tures in OM molecules; either terrigenous OM and freshwater plankton or OI—oxygen index (OI = S3/TOC) shows the pres technogenic pollution, since pentane essentially is the ence of oxygen structures in OM molecules in BS. first in the gasoline series of liquid petroleum HC.

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Methane concentration varies within wide limits 0.003 to 0.49 (up to 0.08 in the majority of points), (from 96 × 10–4 to 2429 × 10–4 mL/kg), depending on which suggests a very active processes taking place in the sampling site and time (Table 1). BS of the Ivankovo Reservoir, though at different The composition of HC gas mixture in BS sampled rates. In 1995, the maximal value of K (0.12) was in 1995 at the sections of Vidogoshch, Konakovo, obtained for BS of Ploski section, situated a short dis Korcheva, and the mouth part of Moshkovichskii Bay tance downstream of Gorodishche section. In 2004– show relatively low concentrations of methane and 2005, ethylene concentration in the samples increased saturated HC and the presence of homologs only of significantly. In two areas, K increased by an order of the series С2–С3. Such BS composition corresponds magnitude, implying that the rate of microbiological to the transformation of OM mostly of natural genesis processes decreases. DS sampled in the sections of in unpolluted parts of the water body. The composi Gorodnya (downstream of Tver City) and Gorodish tion of hydrocarbon gases in BS sampled in 2005 at che (at the site of mixing of OMrich water of the sections and in bays has changed. Relatively low con Shoshinskii Pool and the polluted water of the Volga centrations of methane and saturated HC of С2–С3 R. downstream of Tver C.) show the values of K of fractions were recorded at sections of Gorodnya, Gor 0.49 and 0.2, respectively. Technogenic OM, entering odishche, Ploski, Klintsy, the channel part of Dubna with municipal, domestic, and industrial wastewaters, section and the bays of Vesna, Korovinskii, and Per whose transformation in nature is slow, accumulate in etrusovskii outlet. The results of studying BS gas com Gorodnya section. The Shoshinskii Pool drains a wet position show the transformation of OM of mostly land area rich in organic matter. Further downstream, natural genesis in unpolluted areas within the reser in Gorodishche section, the transformation of tech voir. nogenic OM is more intense, which is likely due to Specific features of BS gas composition in Moshk water, rich in natural OM, which enters from the ovichskii Bay are the high methane concentration and Shoshinskii Pool. the presence of its homologs С2–С5. In 1995, higher The comparison of K values obtained for sediments concentration of saturated HC of the series С2–С4 was samples taken in identical sections in 1995 and 2005 recorded in this section; in 2005, HC of С5 series were has shown that the value of K dropped on the average recorded here. Moshkovichskii Bay receives the 2.5 times in the majority of the examined areas municipal and domestic wastewaters, effluents from a (Vidogoshchi, Ploski, Babninskii bay, Korcheva). The State District Power Plant (SDPP) and other indus value of K near the Moshkovichskii Bay has not trial plants in Konakovo Town. The gases from sam changed. This suggests that the environmental condi ples taken from Shoshinskii Pool near a bridge on the tions near Moshkovichskii Bay have not improved. Moscow–St. Petersburg highway, in addition to high The only exceptions are the sections of Gorodnya and methane concentration, the presence of its homologs Konakovo, where the value of K increased 8 and 1.5 up to С5 were recorded. The BS in NizovkaShosha times, respectively. Thus, the concentration of tech section in 2004–2005 were also found to contain nogenic OM in Konakovo section is increasing insig hydrocarbons up to С5. This confirms that the techno nificantly, its accumulation in Gorodnya section is genic pollution from motor and railway transport still very rapid. This not only determines the level of OM has a negative effect on the ecological state of the res concentration, but also suggests the possibility of ervoir. changes in the occurrence form and the migration As can be seen from Table 1, most samples were capacity of heavy metals. also found to contain unsaturated HC. Unsaturated HC of the saturated series С4–С5 (butanes and HC С2–С4 (ethylene, propylene, and butylenes)— pentanes) were recorded in the study period in differ intermediate products of OM destruction—are very ent parts of the reservoir: reactive because of an unstable double bond. The pres in 1995, in areas of the Shoshinskii Pool and Ploski; ence of such compounds in gases in relatively high in 2004, in areas near Melkovo, NizovkaShosha, concentrations suggest the permanent input into BS of Ploski, and Klintsy; new bioavailable OM, which experiences intense transformation as the result of biodegradation pro in 2005, in sections NizovkaVolga, Nizovka cesses, resulting in constant replenishment of unsatur Shosha, Moshkovichskii Bay, and Dubna. ated HC and even their accumulation. Among the It is worth mentioning that no increase in the con unsaturated HC in the examined samples, methane centration or evident accumulation of petroleum HC shows the highest concentrations, which, in a wide was recorded in those areas. It is likely that the con range, are 2–2500 times greater than that of the near centrations of petroleum HC are determined by the est saturated HC—ethane. The rates of the processes environmental conditions in the period under study. taking place in such cases are characterized by coeffi In the lower part of the reservoir, the dam near cient K, i.e., the ratio of saturated to unsaturated HC: Dubna T. serves as a mechanical barrier, reducing river K = (С2 – С4)sat/(С2 – С4)unsat. The lesser K, the more flow rate and causing the sedimentation of debris, intense is the process of OM transformation. The accompanied by OM accumulation. In the same area, value of K, which is much less than unit, varies from gases can accumulate, whose origin can be due to ter

WATER RESOURCES Vol. 40 No. 3 2013 HYDROCARBON GASES (C1–C5) AND ORGANIC MATTER 289 –0.04 –0.037 –0.067 0.03 0.029 0.052 0.025 0.019 0.023 0.037 is normal butane, 10 –0.06 kn –0.085 –0.047 –0.055 H 4 0.071 0.046 0.043 0.059 0.038 0.016 0.0098 0.048 0.03 0.055 0.044 0.049 0.047 0.035 0.033 0.0458 C n 0.0316 0.057 0.046 0.031 , 4 H 12 2 1 1 1 1 1 1 1 1 1 H 5 –72 /C

WATER RESOURCES Vol. 40 No. 3 2013 290 SAFRONOVA et al. –0.03 –0.016 –0.07 –0.02 –0.031 –0.019 –0.029 –0.017 –0.029 0.02 0.01 0.02 0.03 0.007 0.016 0.014 0.018 0.025 0.014 0.017 0.02 0.007 0.009 0.012 0.0065 0.007 0.0004 –0.037 –0.04 kn –0.099 –0.032 –0.036 –0.047 –0.027 –0.037 –0.045 0.02 0.02 0.017 0.07 0.028 0.04 0.03 0.03 0.02 0.03 0.02 0.03 0.49 0.49 0.20.0120.031 0.15 0.018 0.0049 0.018 0.0069 0.0325 0.008 0.02 0.014 0.023 0.012 0.028 0.027 0.014 0.0026 12 0.027 0.031 0.02 0.02 1 1 1 1 1 1 1 1 1 1 1 1 1 1 H 16.7 19.4 23.9 5 1 1 1

WATER RESOURCES Vol. 40 No. 3 2013 HYDROCARBON GASES (C1–C5) AND ORGANIC MATTER 291 rigenous OM and freshwater plankton; this process ation varied widely—from 0.02 to 29% (Table 1), determines the high concentrations of all HC in the which generate 0.2–9.9 mg of light HC per 1 g of rock gas phase of sediments. Higher concentrations of (S1). The highest concentrations of TOC (from 3 to heavy homologs of methane were recorded in the sam 29%) were obtained in the bays that are overgrowing ples from Shoshinskii Pool area and the Nizovka by aquatic plants. The concentrations of highmolec Shosha section located further downstream. The ular HC and cracking HC (S2) varies within a wide higher concentrations of butane and pentane com range of 0.1–42 mg/g of rock, and the concentration pounds in those points can be attributed to the impact of СО2 during the cracking of residual OM (S3) varies of motor and railway transport on the lines connecting from 0.3 to 23 mg/g of rock. The formation of free HC Moscow and St. Petersburg. This is in agreement with С1–С10 (S1/ТОС) consumes from 5 to 17% of TOC. the character of HC distribution in gas phase of BS. In The highest values of this characteristic (<10%) were the early diagenesis of OM, highmolecular HC may recorded in the sections of Vidogoshch and Nizovka form in the process of chemogenic generation. The Shosha and in Babninskii, Moshkovichevskii, and process of chemogenic generation commonly shows a Korovinskii bays. This suggests that the major portion general regularity in the distribution of components: of OM (more than 80%) is represented by heavy non С1 > С2 > С3 > С4 > С5. However, this regularity does volatile compounds. In the case of autochthonous not hold in this study because of higher concentrations HC, the ratio S1/ТОС correlates with the ratio S1/(S1 of HC of petroleum series and takes the form С3 < С5, + S2), which characterizes the degree of realization of С4 < С5. It is worth mentioning that the higher con the hydrocarbon potential of OM. It is worth men centration of the sum of saturated HC (С4, С5sat) in tioning that the high absolute values of parameter S1, the samples taken in Melkovo and NizovkaVolga sec which manifest themselves in the samples taken in the tions appears to be due to the effect of another seg sections mentioned above, are an indication of the ment of the same highway, which runs along Volga presence of oil HC in top BS layers. The highest con bank upstream of Melkovo section, and the effect of centrations of S1 were recorded in Moshkovichskii and polluted waters discharged in Tver City. Korovinskii bays and in the middle of Omutninskoe On the other hand, the concentrations of saturated shallow area behind the island. The relatively high val HC, i.e., С4, С5, has not changed in the areas of Kona ues of Т parameter at high concentrations of free HC, kovo T. and Moshkovichskii Bay, which are subject to including gaseous, suggest the possible migration of a significant environmental impact of the Konakovo HC, hence the hazard of appearance of hydrocarbon SDPP. Thus, an increase in the share of ecologically compounds in lower layers. This can be clearly seen in clearer gas fuel in SDPP fuel balance has led to the sta Moshkovichskii Bay at the water discharge site from bilization of the environmental state of the nearby treatment facilities, in Babinskii (in 1995, 2005) and areas, as can be seen from the fact that the concentra Korovinskii bays and in Omutninskoe shallow area tions of oil HC in reservoir BS did not changed in the behind the island. period under consideration. The characteristic НI/ОI, which determines the Correlation analysis and the comparison of the ratio S2/S3, can be used to determine the type of OM, character of the distribution curves of methane con its sources, and the transformation character. OM of centration in the samples under study in 1995, 2004, alga, planktonogenic, and terrigenic origin can be and 2005 (the total number of samples was 67), as well identified. Kerogen of alga origin (high S2 and low S3, as its higher molecular homologs showed them to be HI/OI > 1) was recorded in BS of the sections of Gor identical, thus confirming their genetic relationships odnya, Vidogoshch, Shoshinskii Pool, Dubna, near (Fig. 2). The results of correlation analysis show a sig the treatment facilities at Moshkovichskii Bay, nificant positive correlation between methane con Donkhovka mouth, plant overgrowths in Moshkov centration and the total concentration of its homologs ichskii, Peretrusovskii, Korovinskii, Omutninskii, and in BS rxy5% = 0.53 (the critical value of correlation Fedorovskii bays and NizovkaShosha, which is coefficient for 66 samples r5% = 0.25 at 5% significance clearly due to microbiological processes, which deter level). Since the entire data body shows a positive cor mine the degree of decomposition of the abundant relation between the above characteristics, the num aquatic vegetation in those sections and are deter bers of sampling points are not given in Fig. 2 because mined by physicochemical characteristics and the of the large number of samples. The concentrations of structure of BS. The degree of maturity of OM methane and its homologs in individual sample sec increases in the sections of Ploski, Konakovo (1995), tions are given in Table 2. Korcheva, Malye Peremerki Creek, at the outlet of BS samples for determining TOC concentration Moshkovichskii Bay, NizovkaVolga (high S3, low S2, were taken at the major sections of the reservoir (Table HI/OI < 1), kerogen of terrigenous origin appears in BS. 2). Moreover, BS samples were also taken in 2005 in We will use samples with different granulometric bays overgrowing with aquatic plants. BS samples were and lithological composition taken in 2004 in different taken from below the roots of aquatic plants. From sections of the reservoir to consider the effect of granulo 1995 to 2005 the total OM concentration in the solid metric composition on OM content of BS (Tables 2, 3). phase of BS (TOC) in the sections under consider Its low values (0.02–0.6%) are typical of sandy and

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3500

3000

–4 2500

2000

1500

1000 Concentration, mL/kg 10 500

0 BS samples CH4 Total concentration of homologs

Fig. 2. Concentration distribution curves of methane and the total concentration of its higher molecular homologs in BS samples (67 samples). sandyloam samples, which is an order of magnitude BS with higher TOC concentration (from 3.8 to less than TOC values for clay and loam samples (1.0– 6.1%) in the sections of NizovkaShosha, Konakovo, 29.0%) (Tables 2, 3). The minimal values of TOC were and Klintsy are classified by their granulometric com recorded in the samples taken in the areas near the position as loams and silty clays. Maximal methane Peremerki Creek and the sections Melkovo and concentrations were recorded in BS in sections Ploski NizovkaVolga, which, by their granulometric compo and NizovkaShosha. The low value of K for those sition are identified as lightsandy loam, fine consoli sections suggests the intense OM transformation pro dated sand and coarse consolidated sand, respectively cess. (Table 3). In the sections of Peremerki and Nizovka In the BS of the sections of Melkovo and Nizovka Volga, the concentrations of methane and its saturated Volga (with sandy and sandy loam composition), the and unsaturated homologs were minimal (Table 1), value of S3 is, to a different extent, greater than S2 suggesting the insignificant input of fresh OM. The (Table 2). Therefore, OM in BS of those areas can be concentrations of methane and its homologs increase characterized as oxidized, containing mostly oxygen considerably in Melkovo section against the back structural groups (carbonyl, carboxyl, phenol, etc.). This is also confirmed by the values of and ground of low TOC concentration. This suggests an ОI НI (Table 2). The situation in NizovkaShosha section is increase in the share of technogenic component in the reverse. The value of S2 is greater than S3, suggesting composition of the incoming OM. The value of K the priority concentration in OM of highmolecular (Table 1) indicates to an intense process of OM trans HC, including those from the oil series (Table 2). This formation in those parts of the reservoir. The distribu also confirms the interpretation obtained with the use tion of total HC characteristics (S1, S2, S3) in the sam of vaporphase gas chromatography described above. ples is identical to the distribution of TOC (Fig. 3), as In this study, the authors for the first time examined can be seen, in particular, from the high positive corre the isotopic composition of organic carbon in BS of lation coefficient between S1, S2, S3 and TOC (Table 4). the Ivankovo Reservoir. However, the quantitative relationships between indi The isotopic composition of carbon in BS was ces НI and ОI in the samples under study are different. studied in the sections of the Malye Peremerki Creek, In BS in NizovkaVolga section, where oxygen index is Melkovo, NizovkaVolga, NizovkaShosha, Ploski, high, oxygen structures dominate in OM molecules. Konakovo, and Klintsy. The results of this study are Oxygen structures also dominate in BS at Melkovo, given in Table 5. The isotopic composition of carbon located near NizovkaVolga section. In the section at varies within wide limits. The least values (–29, – the Malye Peremerki creek, the hydrogen index is 30‰) characterize Corg in the sections of Konakovo, high; therefore, hydrogen structures dominate in OM NizovkaShosha, Melkovo, and NizovkaVolga. The molecules in BS. highest δ13C (from –26 to –28) are typical of the areas

WATER RESOURCES Vol. 40 No. 3 2013 HYDROCARBON GASES (C1–C5) AND ORGANIC MATTER 293 Table 2. Determination of total OM indices in BS of the Ivankovo Reservoir Sampling site , mg/g , mg/g , mg/g TOC, % / (the number of stations) S1 S2 S3 HI OI HI OI 1995 Gorodnya (1) 4.89 12.25 10.45 6.69 18.3 15.6 1.17 8.56–27.15 14.71–34.76 11.95–23.42 9.61–15.7 15.3–22.1 12.4–14.9 1.23–1.48 Vidgoshchi (2) 17.8 24.7 17.7 12.6 18.7 13.6 1.35 1.72–3.65 6.84–8.69 6.39–7.33 0.88–5.46 15.9–77.7 11.7–83.2 0.93–1.36 Shoshinskii Pool (3) 2.7 7.7 6.86 3.17 46.8 47.5 1.15 Pleski MOLGMI (1) 0.24 0.34 1.45 0.28 12.1 51.7 0.23 Konakovo (1) 0.21 0.59 2.06 0.28 21.0 73.5 0.28 6.11–9.89 15.21–18.81 14.72–14.90 2.10–7.04 26.7–72.4 20.9–70.9 1–1.28 Babninskii Bay (2) 8 17.01 14.8 4.57 49 45.9 1.14 0.3–5.38 0.8–11.88 1.76–10.07 0.74–4.71 10.8–25.5 21.3–23.7 0.45–1.18 Moshkovichskii Bay (2) 2.84 6.34 5.9 2.7 19.6 22.5 0.81 Korcheva (1) 0.37 1.27 3.85 0.87 14.5 44.2 0.33 2004 Malye Peremerki Cr. (1) 0.75 2.35 2.31 0.55 427 421 1.01 MelkovoVidgoshchi (1) 0.39 1.01 1.82 0.42 240 433 0.55 NizovkaVolga (1) 0.45 1.21 3.96 0.51 237 776 0.3 NizovkaShosha (1) 6.39 22.97 12.26 6.1 376 201 1.87 Ploski (1) 3.11 14.98 13.3 5.3 282 251 1.12 Konakovo (1) 2.00 8.83 11.16 3.81 231 293 0.79 Klintsy (1) 3.64 14.25 15.10 5.59 254 271 0.94 2005 Gorodnya (1) 0.08 1.89 0

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Table 3. Granulometric composition of BS Concentrations of mechanical elements, %, vs. their size, mm Name by the granulom Sampling site 1–0.25 0.25–0.05 0.05–0.01 0.01–0.005 0.005–0.001 <0.001 etric composition mm Malye Pere 24.79 42.97 12.80 4.40 7.16 7.88 Loamy sand, light merki Cr. 80.56 19.44 Melkovo 34.55 51.09 7.76 2.80 1.36 2.44 Fine consolidated sand Vyogoshchi 93.40 6.60 NizovkaVolga 57.56 23.64 10.04 4.32 1.96 2.48 Coarse consolidated 91.24 8.76 sand Nizovka 17.81 22.95 28.20 10.40 10.84 9.80 Medium loam, coarse Shosha 68.96 31.04 dust Ploski 22.73 22.47 26.32 10.40 10.00 8.08 Sandy loam, coarsedust 71.52 28.48 Konakovo 29.50 4.82 21.56 10.00 13.36 20.76 Heavy loam, coarse dust 55.88 44.12 Klintsy 11.30 3.26 29.00 12.56 15.00 28.88 Light clay, silty 43.56 56.44 of Ploski, Klintsy, and Malye Peremerki. As men areas of Konakovo, Melkovo, and NizovkaVolga tioned before, parameter HI/OI is determined by the (HI/OI < 1, δ13С, –29 to –30‰). The main process ratio of oxygen to hydrogen atoms in OM. The terrig here is the input of terrigenous OM. In the areas near enous material contains many oxygen functional the sections of Ploski, Klintsy, and Malye Peremerki, groups. Therefore, it has low HI/OI ratio, and the ter highly oxidized OM (HI/OI > 1) with heavier isotopic rigenous OM shows lesser values of δ13С. These are the composition (HI/OI > 1, δ13С –26 to –28‰) accu

25

/L 20

g

m

,

n

o i

t 15

ra

t

n

e c

n 10

o C

5

ТОС 0 S3 S 1 2 2 3 S 4 5 1 6 7 Sample nos.

Fig. 3. Distribution of total characteristics S1, S2, S3, TOC in BS samples (for samples of 2004). Sampling sites: (1) Malye Pere merki Cr., (2) MelkovoVidogoshchi, (3) NizovkaVolga, (4) NizovkaShosha, (5) Ploski, (6) Konakovo, (7) Klintsy.

WATER RESOURCES Vol. 40 No. 3 2013 HYDROCARBON GASES (C1–C5) AND ORGANIC MATTER 295 mulates, indicating to the large contribution of plank Table 4. Coefficients of pair correlation between major tonogenic material. As mentioned in [3], a correlation characteristics of pyrolytic gas chromatography should exist between parameter HI/OI and δ13С. Such Character TOC relationship was really established for OM in BS of istics S1 S2 S3 most sections in the Ivankovo Reservoir. However, this regularity does not hold in NizovkaShosha sec S1 1 tion: here BS show high values of HI/OI (18.7), as it is S 0.984 1 typical of the case where planktonogenic plant mate 2 rial is delivered and accumulated under reduction S3 0.783 0.858 1 conditions. Additionally, they show lower values of TOC 0.905 0.957 0.967 1 δ13С ( –29.82‰), as was the case with the accumula tion of terrigenous detritus. This can be attributed to the input of specific OM in water of the Shosha R., Table 5. Isotopic composition of Corg in BS of the Ivankovo which drains swampy areas and empties into the reser Reservoir voir in this part. OM in BS of the Malye Peremerki Sampling site δC13, ‰ Creek also shows specific geochemical features— equal values of the hydrogen and oxygen indices Malye Peremerki Cr. –28.77 13 (HI/OI = 1) and a medium value of δ С among all Melkovo –29.86 examined samples (–28.77‰) because of the input of technogenic OM with wastewaters. NizovkaVolga –29.37 NizovkaShosha –29.82 Ploski –26.21 CONCLUSIONS Konakovo –30.86 The distribution of gas hydrocarbons C1–C5 in BS Klintsy –28.08 of the Ivankovo Reservoir is studied for the first time. The gas field of BS is different in different parts of the reservoir in terms of both the level of gas saturation Chemistry, Russian Academy of Sciences) for labora and the spectrum of hydrocarbon gases. This suggests 13 tory measurements of δ Corg in BS samples, and N.V. the heterogeneity of OM composition in the sedi Kirpichnikova (Water Problems Institute, Russian ments and the different conditions of its input and Academy of Sciences) for her help in expedition transformation processes. Saturated HC from meth works. ane to pentane C1–C5, including isomers iC4 and i C5 and unsaturated compounds C2–C4. The correlation that was found to exist between the REFERENCES distributions of methane and its higher molecular 1. Brodskii, E.S., Lukashenko, Yu.M., Kalinkevich, G.A., 1 homologs, confirms their genetic relationships in BS. and Savchuk, S.A., Identification of Petroleum Prod The dynamics of the processes was evaluated. The ucts in Environmental Samples Using Gas Chromatog obtained results show an increase in the rate of micro raphy and Gas Chromatography–Mass Spectrometry, biological processes and OM transformation in most Zhurn. Analiticheskoi Khimii, 2002, vol. 57, no. 6, 2 areas of the Ivankovo Reservoir. The only exceptions pp. 486–490. are the zones of Moshkovicheskii Bay and the sections 2. Galimov, E.M., and Kodina, L.A., Issledovanie organ 3 of Gorodnya and Konakovo, where technogenic OM icheskogo veshchestva i gazov v osadochnykh tolshchakh 4 was found to accumulate and the ecological situation dna mirovogo okeana (Studying Organic Matter and did not improve. Gases in Sedimentary Strata on World Ocean Bed), Moscow: Nauka, 1982. It is shown that the sources of OM have great infor mativity as biogeochemical markers and can be used 3. Galimov, E.M., Kodina, L.A., Stepanets, O.V., and 3 Korobeinik, G.S., Biogeochemistry of the Russian to assess the rate of transformation processes of hydro Arctic. Kara Sea: Research Results under the SIRRO carbon gases. The isotope composition of carbon of Project, 1995–2003, Geokhimiya, 2006, no. 11. OM in BS of the Ivankovo Reservoir δ13С is evaluated. 4. Dzyuban, A.N., Role of Methane Cycling in Organic This characteristic is shown to vary from –26.21 to – Matter Turnover in Different Types of Lakes, Water 30.86‰. Some difference in the isotopic composition Resour., 2003, vol. 30, no. 4, pp. 413–421. is due to the predominant input of OM of terrigenous, 5. Zhizhchenko, B.P., Uglevodorodnye gazy (Hydrocar planktonogenic, and technogenic origin in different bon Gases), Moscow: Nedra, 1984. parts of the reservoir. 6. Zhil’tsova, L.I., Primenenie piroliticheskoi gazovoi khromatografii dlya izucheniya organicheskogo vesh 4 ACKNOWLEDGMENTS chestva pri geokhimicheskikh issledovaniyakh (Applica tion of Pyrolytic Gas Chromatography for Studying The authors are grateful to V.S. Sevast’yanov (Ver Organic Matter in Geochemical Studies), Moscow: nadsky Institute of Geochemistry and Analytical VIMS, 1987.

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7. Kodina, L.A., Tokarev, V.G., Korobeinik, G.S., et al., 14. Fedorov, Yu.A., Tambieva, N.S., Gar’kusha, D.N., Natural Background of Hydrocarbon Gases (C1–C5) in and Khoroshevskaya, O.V., Metan v vodnykh ekosiste Kara Sea Water Mass, Geokhimiya, 2008, no. 7, makh (Methane in Aquatic Ecosystems), Rostovon pp. 721–733. Don: Rostizdat, 2005. 8. Martynova, M.V., On the Chemical Composition of Water and Deposits in a Small Lake, Geokhimiya, 1995, 15. Shepeleva, E.S., Ecological–Geochemical Studies of no. 6, pp. 905–909. the Behavior of Heavy Metals in Aquatic and Terres trial Ecosystems of the Ivankovo Reservoir, Extended 9. Martynova, M.V., Gas Composition of Silts in Fresh Abstract of Cand. Sci. (Geol.–Min.) Dissertation, Mos water Lakes, Water Resour., 2000, vol. 27, no. 2, pp. 182–188. cow: MSU, 2004. 10. Martynova, M.V., Lomova, D.V., and Nezametdi 16. Espital’e, G., Drouet, S., and Markuis, F., Assessment nova, D.A., Spatial and Temporal Distribution of of Oil Content with the Use of RockEval Devise with Gases in the Mozhaisk Reservoir Silts, Water Resour., a Computer, Geol. Nefti Gaza, 1994, no. 1, pp. 23–32. 1999, vol. 26, no. 1, pp. 67–71. 11. Nemirovskaya, I.A., Brekhovskikh, V.F., and 17. Yashin, Ya.I., Major Achievements of Chromatogra Kazmiruk, T.N., Origin of Hydrocarbons in Bottom phy in the XX Century, Laboratornyi Zhurn, 2002, no. 1 2 Sediments of the Ivankovo Reservoir, Water Resour., (1), pp. 8–10. 2009, vol. 36, no. 3, pp. 337–344. 18. Korobeinik, G.S., Tokarev, V.G., and Waisman, T.I., 12. Orlov, D.S., Kasparov, S.V, Min’ko, O.I., et al., The Geochemistry of Hydrocarbon Gases in the Kara Sea Phenomenon of Formation of Dispersed Carbon in Sediments, Rep. Polar Mar. Res, 2002, vol. 419, Soils, Dokl. Akad. Nauk SSSR, 1987, vol. 294, no. 1, pp. 158–164. pp. 212–215. 13. Topolov, A.A., Donnoe gazoobrazovanie v ozerakh 19. Tung, J.W.T., and Tanner, P.A., Instrumental Deter Zabaikal’ya (Bottom Gas Formation in Transbaikalian mination of Organic Carbon in Marine Sediments, Lakes), Novosibirsk: Nauka, 1990. Mar. Chem., 2003, vol. 80, no. 2–3, pp. 161–170.

SPELL: 1. Brodskii, 2. Zhurn, 3. Galimov, 4. veshchestva

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