ISSN 00978078, Water Resources, 2015, Vol. 42, No. 3, pp. 331–339. © Pleiades Publishing, Ltd., 2015. Original Russian Text © D.N. Gar’kusha, Yu.A. Fedorov, 2015, published in Vodnye Resursy, 2015, Vol. 42, No. 3, pp. 288–297.
WATER QUALITY AND PROTECTION: ENVIRONMENTAL ASPECTS
Distribution of Methane Concentration in Coastal Areas of the Gulf of Petrozavodsk, Lake Onega D. N. Gar’kushaa, b and Yu. A. Fedorova a
Institute of Earth Sciences, Southern Federal University, ul. R. Zorge 40, RostovonDon, 344090 Russia b Hydrochemical Institute, prosp. Stachki 198, RostovonDon, 344090 Russia email:
[email protected],
[email protected] Received May 4, 2012
Abstract—The results of manyyear observations of methane concentration in the water and bottom sedi ments of coastal areas in the Gulf of Petrozavodsk are given. The effect of various natural and anthropogenic factors on the formation and distribution of methane. Keywords: methane, concentration, distribution, water, bottom sediments, coastal areas, pollution DOI: 10.1134/S0097807815030045
INTRODUCTION An urgent current problem is the global climate change, which, among others greenhouse gases, is influenced by methane [8]. Aquatic ecosystems, as a source of methane emission into the atmosphere, pro duce it mostly in the process of anaerobic biochemical decay of organic matter (OM). Methane in water objects can originate either from in situ processes or from municipal and industrial wastewaters or waters of tributaries [3, 6, 17–20]; also it can be washed out from soils by rainwater [3, 22], a process that mostly affect methane concentration in coastal waters [3, 20]. The results of experimental and mathematical modeling [16] show an increase in methane concen trations and fluxes in the system bottom sediment (BS)–water–atmosphere with increasing ambient temperature; this, along with organic pollution, can stimulate the generation and emission of methane at a global scale. The studies carried out in Lake Onega are of importance as they give new data on the formation and distribution of methane concentrations in water and BS as a possible characteristic of the extent of anthro pogenic impact on the coastal water areas of the lake. The obtained information can also contribute to the better understanding of methane cycle in freshwater ecosystems. THE OBJECT AND METHOD OF STUDIES The Gulf of Petrozavodsk is a major gulf in Lake Onega (1.3% of lake area). The length of the gulf is 19 km, its mean width is 7 km, water area is ~125 km2, and the mean depth is 18.2 m [12]. Coast outline is rel atively smooth, and the bed relief is slightly dissected. The Ivanovskie Islands and a shallow zone near
Petrozavodsk City coast, which separate the gulf from the open lake, serve as a natural threshold, which lim its water exchange with the central pool [13]. Nearly the entire area of the gulf coastal zone is composed of sands with different coarseness and sandy silts [14]. These deposits show low redox potential (Eh varies from –284 to +47, pH 6.7–7.1) and high OM content [15]. Boulder–pebble deposits occur in some areas, clayey silts are even rarer. Samples of water and BS were taken in the course of landbased survey in the summers (late June–early July) of 2007–2010 aimed to study methane concen trations. The samples were taken in the coastal areas both adjacent to Petrozavodsk City and remote from it (Fig. 1), as well as in tributaries flowing into the Gulf of Petrozavodsk. Observations of the daily dynamics of its concentrations in lake water were carried out with an interval of 4 h. To assess the effect of soils on meth ane concentrations in the water of lake coastal zone and its tributaries, samples were taken from soils, storm and drainage sewages, and those in areas adja cent to the city. Water and BS samples were commonly taken from the shore (at a depth of up to 1.0 m). In the course of study, water was taken from the surface horizon (0.1 m), BS samples were sands and silts (0–2, 2–5, and, at some stations, 5–10 cm). To determine meth ane concentration, peats were dug along a soil profile, and soil samples were taken from their walls at differ ent depths. The samples were taken, transported, stored, and used to determine methane concentration by vaporphase gas chromatography, in accordance with procedures described in detail in [6, 20, 21]. The lower methane detection limit was 0.1 µL/L in water and 0.01 µg/g of wet sediment (deposits, soil) in BS and soils; the total error of determination was 5–10%.
331
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GAR’KUSHA, FEDOROV Logmozero
N
33 32 31 512 511
513
514
510
Gu
59 58
P
E
24 25
T
R
23
O
57
21 22
Z
A
26
56 55 13 11 12 14
V
O
D
S
lf o fP
515
etr oz av o
ds k
54
K 53
La ke On ega
41 1–5 52
51
Fig. 1. Layout of water and BS sampling stations in the Gulf of Petrozavodsk, Lake Onega, and its tributaries in June– July 2007–2010.
RESULTS AND DISCUSSION Methane in Water The concentration of methane in water in coastal areas of the Gulf of Petrozavodsk varied within 2.6– 122.2 (on the average, 31.5) µL/L (n = 48) (Table 1). Minimal concentrations (2.6–10.0 (5.8) µL/L) in all observation periods were recorded at stations remote from Petrozavodsk and lying beyond the zones of strong anthropogenic impact (stations 51, 52, 514, 515). Maximal concentrations were recorded at sta tion 54 (84.0–122.2 (109.0) µL/L), adjacent to one of the largest industrial regions of the city, including Petrozavodsk BreadBaking Complex, distillery, Karelian FishWorks, Avangard Shipyard, and a dock yard. High concentrations (16.8–64.4 (42.6) µL/L) were recorded in Solomennyi Strait (stations 5–11 and 5–12), which connects the Gulf of Petrozavodsk and Logmozero, with the Petrozavodsk SawMill and Furniture Plant. High methane concentrations were also recorded in water samples from stations 53 and 59, located at a petroleum base and a woodworking enterprise, respectively.
The formation of zones of higher methane concen trations in the water and BS of aquatic ecosystems under the effect of domestic and industrial wastewa ters, rich in anthropogenic OM, were considered in detail in [3, 18–20]. Wastewaters often contain high concentrations of substrates, such as acetate, metha nol, formiate, methylamines, СО2, Н2, which serve as nutrients for methanogens, and, hence, can be imme diately consumed by them not only when contained in BS, but also in the water mass, as confirmed by the results of studies of domestic and industrial wastewa ters from various plants and households [20]. In such cases, methanogenesis becomes much more active, resulting in the formation of zones with aboveback ground methane concentrations in water and sedi ments. Methane concentration in water in zones sub ject to strong anthropogenic impact and eutrophica tion is generally four times as large as its concentration in water bodies and streams beyond such zones [4]. Higher methane concentrations (up to 39.5 µL/L) relative to its mean values were recorded in some peri ods in the zone of inflow of the rivers of Neglinka and Lososinka. Methane concentration in those tributaries WATER RESOURCES
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45 40 35 30 25 20 15 10 5 0
333
(а)
40 st. 14 (2007)
35 30 CH4, μL/L
CH4, μL/L
DISTRIBUTION OF METHANE CONCENTRATION IN COASTAL AREAS
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y = 4.4x – 55.3
15
r = 0.92(P < 0.01)
5
Fig. 2. Diurnal dynamics of methane concentration in water of the Gulf of Petrozavodsk near Lososinka R. mouth (st. 55) in July 2009.
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20 10
23:00 3:00 7:00 11:00 15:00 19:00 23:00 3:00 Time, h
0 12 140 120
13 14 15 16 17 18 t, °C (b)
19 20 21 22
st. 21 (2007) st. 21 (2008)
CH4, μL/L
100 80
st. 23 (2008)
y = 7.9x – 88.9
60
r = 0.66(P < 0.01)
40 20 0 10
11
12
140 st. 54 (2009)
120
13
14 t, °C (c)
15
16
17
st. 54 (2010)
st. 54 (2008)
100 CH4, μL/L
varies within 1.9–38.1 (14.9) µL/L (n = 17) and 1.5– 115.9 (34.5) µL/L (n = 19), respectively. At the same time, both rivers, as a rule, showed an increase in methane concentrations from zones beyond the city toward the mouth, which is due to the increasing tech nogenic load and accumulative properties of soils in this direction and, consequently, higher rate of meth ane generation in BS [20]. Studies showed that methane concentration in water in coastal zones of the Gulf of Petrozavodsk is 10 times as high as that in the open water area of Lake Onega; in some areas, this excess ratio was more than 100. Thus, in June 1987, methane concentration in surface and bottom water layers in an open water area of Lake Onega varied within 0.6–6.2 (2.0) and 0.8– 7.6 (3.4) µL/L, respectively [20]. A decrease in meth ane concentration in the direction from the coastal zone into the open water is also typical of other water bodies and streams [3, 6, 17–20]. This is mostly due to a decrease in the amount and lability of OM of both nat ural and anthropogenic origin (resulting in a decrease in methane generation in BS), as well as greater warming of the shallow coastal zone. Daily observations (Fig. 2) showed a considerable variations of the series of methane concentration in water in the Gulf of Petrozavodsk (st. 55), where its concentrations within a day varied within 12.8–39.5 (19.5) µL/L (the variation coefficient of 34%). Maxi mal values were recorded in the daytime in the period of highest water warming, which enhances methane generation in BS; methane concentrations in water in the morning and evening were minimal. The tempera ture regime determines not only daily, but also sea sonal and yeartoyear variations in methane concen tration [20], as can be seen from plots constructed based on observational data of 2007–2010 for coastal areas of the Gulf of Petrozavodsk, as well as the Loso sinka and Neglinka rivers (Fig. 3). This is in agreement with the conclusions [23] that water temperature is a key factor governing the rate of methanogenesis in water bodies and streams. Considerable deviations from the lines on the plots in Fig. 3 that approximate those relationships are typical of points corresponding
st. 14 (2010)
25
st. 59 (2007)
80
st. 59 (2010)
st. 54 (2007)
60 y = 5.3x – 54.6
40
r = 0.64(P < 0.01)
20 0 9
10 11 12 13 14 15 16 17 18 19 t, °C
Fig. 3. Relationships between methane concentration and water temperature according to data of 2007–2010. (a) Lososinka R., (b) Neglinka R., (c) Gulf of Petrozavodsk.
to stations 14, 21, 23, 54, 59, which are subject to a strong anthropogenic impact; this may be due to additional methane inflow with domestic and indus trial wastewaters. Methane in Bottom Sediments The distribution of methane concentration in top horizons (down to 10 cm) of BS in the examined
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14.4 –
14.2
14.2 14.0
Neglinka R., near bridge, 61°47′28″/34° 20′59″ prosp. Pervomaiskii
Neglinka R., 1 km down 61°47′23″/34° stream of repair and engi 19′53″ neering works
Neglinka R., downstream 61°47′23″/34° of repair and engineering 18′58″ works
Neglinka R., upstream 61°47′11″/34° of repair and engineering 18′53″ works
Neglinka R. upper bound 61°46′16″/34° 17′41″ ary of Petrozavodsk
22
23
24
25
26
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32
31
Logmozero
Logmozero
Logmozero
Drainage ditch, Petroza Near station vodsk City, Drevlyanka 26 residential district
– –
61°51′25″/34° 19′45″ 61°51′35″/34° 18′41″
18.2
14.5
61°47′54″/34° 22′09″
Neglinka R., mouth
21
61°50′58″/34° 22′10″
16.1
Lososinka R., upper 61°45′27″/34° boundary of Petrozavodsk 20′44″
15
–
15.9
Lososinka R., 61°46′53″/34° upstream of tractor works 22′11″
14
61°45′30″/34° 18′25″
16.0
Lososinka R., downstream 61°47′07″/34° 22′51″ of tractor works
Lososinka R., dam
12
13
Lososinka R., mouth
11 21.0
T, °C
–
–
16.8
–
12.9
31.9
29.1
–
24.6
115.9
14.6
38.1
20.2
36.4
25.8
CH4, µL/L
July 3–7, 2007
61°47′07″/34° 23′12″
Coordinates, N/E 18.1
Station location 61°47′13″/34° 23′45″
Station no.
–
–
14.5
–
13.0
11.0
12.0
11.0
11.0
11.5
13.5
14.0
13.0
15.0
14.0
T, °C
–
–
7.6
–
–
17.0
–
14.0
2.2 0.2 1.5
14.0
–
15.0
5.6
8.3
69.2
16.0
16.0
109.1 1.5 11.8
14.0
15.0
15.0
–
16.0
T, °C
–
–
13.9
–
4.2 <0.1
1.5
–
47.0
11.3
18.4
18.6
18.4
–
14.3
–
15.9
–
–
16.5
15.0
3.8 0.1 45.1
15.2
–
–
18.5
T, °C
14.4
52.6
27.5
–
17.2
–
34.8
–
–
73.7
10.1
24.3
–
–
26.9
CH4, µL/L
July 3–7, 2010
1.9
2.6
–
9.0
CH4, mL/L
July 2–5, 2009
7.4
7.8
4.0
11.6
8.4
CH4, µL/L
June 15–20, 2008
Table 1. Methane concentration in surface water layer of Lake Onega and its tributaries (the top number is methane concentration in storm runoff)
334 GAR’KUSHA, FEDOROV
2015
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515
514
513
512
511
510
59
58
57
56
53
54
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52
51
41
Station no.
Station location
61°46′54″/34 °24′48″
Gulf of Petrozavodsk, industrial district
61°50′20″/34 °22′55″ 61°50′12″/34 °26′03″ 61°49′16″/34 °30′46″
Gulf of Petrozavodsk, botanic gardens
Gulf of Petrozavodsk, 2.5 km from Solomennoe V. Gulf of Petrozavodsk, 7 km from Solomennoe V.
Gulf of Petrozavodsk, zone 61°47′15″/34 near Lososinka R. mouth °23′55″ 61°47′35″/34 Gulf of Petrozavodsk, berth °23′42″ Gulf of Petrozavodsk, 61°47′57″/34 area near Neglinka R. °22′11″ mouth Gulf of Petrozavodsk, 61°48′16″/34 °21′02″ Varkausa embankment Gulf of Petrozavodsk, 61°48′49″/34 °19′44″ woodworking plant Gulf of Petrozavodsk, 61°49′45″/34 °18′19″ beach Gulf of Petrozavodsk, 61°50′36″/34 °21′09″ Solomennoe V. Strait between the Gulf 61°50′47″/34 of Petrozavodsk °21′28″ and Logmozero
16.9
61°44′26″/34 °29′55″
– 64.4
– 18.0
10.0 5.3
14.0
14.0
14.0
14.5
42.0
–
–
18.0
–
–
20.2
24.1
16.3 16.0
23.7
84.0
44.7
5.4
7.1
–
CH4, µL/L
17.5
17.0
18.3
18.5
–
T, °C
July 3–7, 2007
61°43′09″/34 °31′37″
61°43′52″/34 °30′33″ 61°40′46″/34 °33′37″
Coordinates, N/E
Gulf of Petrozavodsk, Derevyanskaya inlet Gulf of Petrozavodsk, 2 km from petroleum tank farm Gulf of Petrozavodsk, near petroleum tank farm
Sel’gskaya R., mouth
Table 1. (Contd.)
11.0
11.5
13.0
14.5
15.0
13.0
–
10.0
12.0
13.0
13.5
10.0
12.5
14.0
14.0
–
T, °C
2.6
–
–
17.0
10.9 0.4 8.2
15.0
16.0
15.0
17.0
17.0
16.0
14.0
16.0
12.0
–
–
–
–
T, °C
–
–
7.1
34.9
16.8
13.9
86.5
3.8
35.7
20.2
39.5
122.2 0.6
–
–
–
–
CH4, mL/L
July 2–5, 2009
37.2
33.1
25.5
–
7.4
10.5
24.0
29.8
109.5
28.8
4.2
3.5
–
CH4, µL/L
June 15–20, 2008
–
15.2
15.3
17.6
17.5
15.4
15.5
15.5
15.8
–
16.4
15.8
15.2
15.1
–
17.0
T, °C
–
10.6
18.3
49.1
63.6
26.9
74.3
8.9
20.1
–
17.9
120.2
24.3
7.5
–
21.7
CH4, µL/L
July 3–7, 2010
DISTRIBUTION OF METHANE CONCENTRATION IN COASTAL AREAS 335
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GAR’KUSHA, FEDOROV
water area of Lake Onega is extremely uneven, vary ing from <0.01 to 35.0 µg/g of wet sediment (with a median of 0.29 µg/g, n = 59). Coastal sand deposits beyond the zones of strong anthropogenic impact (stations 51, 52, 514, 515) show minimal gas concentrations—from <0.01 to 0.02 µg/g (Table 2). With an increase in the concentration of fine material in deposits, methane concentration appreciably increases, especially, in silty sediments of areas sub ject to strong technogenic load. Thus, methane con centration was maximal (27.7–32.5 µg/g) in clayey silts at station 54, adjacent to an industrial region of Petrozavodsk. Methane concentrations higher than in clean areas were recorded in deposits (fine silty sand) near the petroleum farm (st. 53) and near the woodworking enterprise (st. 59). The concentration of methane in the rivers of Lososinka and Neglinka varied from <0.01 to 14.0 and from <0.01 to 7.8 µg/g, respectively, with maximal concentrations in silty BS at river mouths and minimal concentrations in sandy BS. Analysis of methane distribution in coastal BS of the Gulf of Petrozavodsk and its tributaries showed that its concentrations in relatively clean areas (stations 51, 52, 510, 513, 514, 515, 15), its concentration in surface (0–2 cm) and subsurface (2–5 cm) layers were at the same (low) level or slightly decreased downward (Table 2), thus suggesting lower microbiological activity and methanogenesis limiting by the input of OM (pri marily, labile) into deposits [3, 20]. In the deposits sampled in areas near anthropo genic sources (stations 53, 54, 59, 41, all stations on the rivers of Neglinka and Lososinka, except for stations 15 and 26) methane concentration in the subsurface layer (2–5 cm) was higher than that in the surface layer (0–2 cm) because of a decrease in the redox potential down from the surface into the silt [1, 15] and, as a consequence, more active gas generation by methaneproducing bacteria [9, 20]. In a 15cm BS core column, sampled at the mouth of the Sel’gskaya River, methane concentration in the bottom part of the sample abruptly increased to 35.0 µg/g, which may be due to the strong polluting effect of the past discharges of the largest Petrozavodsk Poultry Plant in Karelia, as well as industrial enterprises of Onezhs kii Residential District of Petrozavodsk City. A reliable linear relationship between methane concentration in surface BS layer (0–2 cm) and water (r = 0.69; P < 0.01) was found to exist in the coastal areas of the Gulf of Petrozavodsk, Lake Onega. This, along with a decrease in its concentration in the direc tion BS–water (by an order of magnitude on the aver age), suggests the predominance of methane input into water from BS. Notwithstanding the excessive moistening throughout the year (the total annual precipitation is 550–750 mm), intense soil washing, and the high bogginess of Lake Onega drainage basin [12], the washout of methane from soils by rainwater and its
subsequent inflow into coastal waters of the Gulf of Petrozavodsk and its tributaries with rain (storm) and drainage runoff is insignificant. This can be seen from methane concentrations in the rain and drain waters in the study area, varying from <0.1 to 1.5 (with an average of 0.6) µL/L (n = 7) (Table 1), which is more than an order of magnitude less than methane concentration in water of the coastal zone of the gulf and its tributaries. Methane concentration in soils in the study area var ies from <0.01 to 4.02 µg/g wet soil (with a median of 0.10 µg/g; n = 36) (Table 3), which is somewhat higher than that in the soils of steppes [5] and tundra [2]. The soil profile generally shows a decrease in methane con centration from the surface humusaccumulation hori zon to subsurface heavily washed podzol horizon, com monly strawcolored. Below, in a darkbrown illuvial– humus horizon, methane concentration increases, often exceeding its concentration in the surface humus accumulation layer. Deeper into the section, methane concentration gradually decreases. Maximal methane concentrations were detected in the surface, heavily moistened humusaccumulation soil layer, where large amount of partially decayed forest litter is present. CONCLUSIONS The distribution of methane concentration in water and BS in the coastal areas of the Gulf of Petrozavodsk is uneven. Its concentrations in areas remote from anthropogenic pollution sources never exceed 10.0 µL/L and 0.02 µg/g in water and BS, respectively. The latter, in addition to a generally low methane concentration, shows a slow decrease in its concentration from bed surface or does not change. In zones of heavy anthropogenic pollution, the con centration of gas is generally >30.0 µL/L in water, >0.1 in sand deposits, and >1.0 µg/g in silts. BS of such areas, in addition to the high methane concen tration throughout the BS core column, shows an increase in its concentration deep into BS. Methane concentration in the surface water layer of coastal areas is an order of magnitude higher than in open water areas of Lake Onega, while near large sources of anthropogenic pollution, this ratio is more than 100. Methane concentration in water in the coastal zone of the Gulf of Petrozavodsk and its tributaries is deter mined mostly by BS, as can be seen from the close lin ear relationship between methane concentrations in the surface BS layer and water. Methane concentra tion in BS, in its turn, directly depends on the amount and lability of OM, which are determined by both the lithologic type of BS and the degree and character of anthropogenic impact. The temperature regime also has considerable effect on the time and space variations of methane concentra tion. Some methane enters the coastal zone of the gulf with domestic and industrial wastewaters or with water of tributaries. The effect of those sources causes the for WATER RESOURCES
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Table 2. Methane concentration in the top BS horizon of Lake Onega and its tributaries, 2007–2009 Station no. 11
12
13
14 15 21 22
23 25 26 41
51 52 53 54 59 510 513 514 515
Sampling CH4, µg/g horizon, wet sediment cm 0–2 5–8 0–2 2–5 0–2 2–5 0–2 2–5 0–2 2–5 0–2 2–5 0–2 2–5 0–2 2–5 0–2 2–5 0–2 2–5 0–2 2–5 5–10 0–2 2–5 0–2 2–5 0–2 2–5 0–2 2–5 5–10 10–15 0–2 2–5 0–2 2–5 0–2 2–5 0–2 2–5 0–2 2–5 0–2 2–5 0–2 2–5 0–2 2–5 0–2 2–5
WATER RESOURCES
1.2–6.7 14.0 0.11 0.38 0.11 0.29 0.01 0.03 0.32 2.90 <0.01 0.02 0.14–0.30 0.45 0.12 0.08 3.2 7.8 <0.01 0.02 1.20 3.50 1.80 0.30 0.64 0.29 0.24 0.95 0.32 0.75 1.1 6.5 35.0 0.02 <0.01 0.01 <0.01 0.14 1.6 27.7 32.5 0.51 1.2 <0.01 <0.01 0.01 <0.01 0.02 0.01 0.01 <0.01 Vol. 42
Visual characteristic of BS Dark gray aleurite silt with admixture of fine sand The same Dark brown fine sand with admixture of aleurite material The same Dark gray fine silty sand The same Yellowbrown fine sand The same Coarse silty sand from brown to black color The same Yellowbrown medium sand with gravel The same Dark brown fine silty sand The same Yellowbrown fine silty sand with gravel The same Dark gray sand–aleurite silt The same Yellowbrown coarse sand with gravel The same Dark gray sand–aleurite silt The same The same, more dense Dark brown fine silty sand The same Black sand–aleurite silt Brown medium silty sand Graybrown fine silty sand The same Dark gray sand–aleurite silt The same Denser, dark gray up to black sand–aleurite silt with hydrotroilite leather coats The same Fine brown sand with gravel The same Medium yellowish–brown sand The same Fine yellowgray silty sand The same, no more dark Dark gray to black clayey silt with sand admixture and putrefactive smell The same Fine dark brown silty sand Fine dark gray silty sand Medium yellowishbrown sand The same Medium dark brown sand The same Medium brown sand The same Medium yellowbrown sand The same
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Table 3. Methane concentration in soils in the study area, 2007–2010 CH4, µg/g wet soil
Station no. and location
Horizon, cm
15, 3–5 m from the Lososinka R. channel
0–2
0.06
2–5 5–10 10–15 15–20 20–25 0–2
0.05 0.07 0.16 0.15 0.12 0.30
0–2
0.09
2–5 5–10
0.10 0.16
10–15 15–20 20–25 0–2
0.15 0.18 0.17 0.04
2–5 5–10
0.05 0.01
15, in the bank of the Lososinka R. 41, 3–5 m from the channel of the Sel’gskaya River
26, 3–5 m from the Neglinka R. channel
26, in the bank of the Neglinka R. Petrozavodsk C., ul. Promyshlennaya, the yard of a multistorey building
21, on the bank of the Neglinka R. 23, 3–5 m from the Neglinka R. channel 25, in the bank of the Neglinka R. 513a, botanic garden, 500 m from Lake Onega 513b, botanic garden, 500 m from Lake Onega 514, botanic garden, 200 m from Lake Onega Drainage ditch, Petrozavodsk C., Drevlyanka residential district
Visual characteristic of soils Dark brown to black humusaccumulation horizon under litter Lighter humus horizon Strongly washed strawcolored podzol horizon Dark brown illuvialhumus horizon The same The same Dark brown to black humusaccumulation horizon
0–2 0–2
0.29 2.4
0–2 2–5 0–2
0.42 1.6 4.02
0–2
0.05–0.10
Dark brown to black humusaccumulation horizon under litter The same Lighter humus horizon with dark brown and light gray spots Dark brown illuvial horizon The same The same Dark brown to black humusaccumulation horizon under litter Lighter humus horizon with brown and light gray spots Strongly washed grayish–strawcolored podzol hori zon The same Dark gray illuvialhumus horizon The same The same The same Dark brown humusaccumulative horizon Dark gray humus horizon The same Lighter humus horizon Strongly washed grayish–strawcolored podzol hori zon Dark brown humusaccumulative soil horizon Strongly wetted darkbrown humusaccumulative horizon with partially decomposed litter, mouldable Wet dark brown humusaccumulative soil horizon The same Strongly wetted dark brown humusaccumulative horizon with partially decayed litter, mouldableÿ Dark brown humusaccumulative horizon under litter
0–2
0.07
The same
0–2
<0.01
10–15 15–20 20–25 25–30 30–35 0–2 0– 2–5 5–10 10–15
0.01 0.08 0.04 0.02 <0.01 0.09–0.10 0.19 0.19 0.12 0.09
Dark brown soil inundated by drainage water
WATER RESOURCES
Vol. 42
No. 3
2015
DISTRIBUTION OF METHANE CONCENTRATION IN COASTAL AREAS
mation of zones with higher methane concentration sin water and BS, which are now of local occurrence and are confined mostly to industrial regions of the city. The effect of methane export from soils by rainwater on its concentration in water in the coastal zone of the Gulf of Petrozavodsk is insignificant. The established limits of methane concentration in relatively clean and anthropogenically polluted areas can be used to assess the pollution of coastal areas of Lake Onega. ACKNOWLEDGMENTS The authors are grateful to N.S. Tambieva (Hydro chemical Institute) for methane concentration deter minations and S.B. Potakhin (Karelian State Peda gogical Academy) for help in the studies. This study was supported by the program “Leading Scientific Schools” NSh5548.2014.5 of RF Presi dent; G/K 1334, and G/K 5.1848.2014.5/K. REFERENCES 1. Belkina, N.A., Pollution of bottom sediments in the Petrozavodsk Bay of Lake Onega with oil products, Water Resour., 2006, vol. 33, no. 2, pp. 163–169. 2. Gal’chenko, V.F., Dulov, L.E., Kramer, B., et al., Bio geochemical processes of methane cycle in the soils, bogs, and lakes of Western Siberia, Mikrobiology (Mos cow), 2001, vol. 70, no. 2, pp. 175–185. 3. Gar’kusha, D.N. and Fedorov, Yu.A., Metan v ust’evoi oblasti reki Don (Methane in the Don Mouth Area), RostovonDon: Rostizdat, 2010. 4. Gar’kusha, D.N. and Fedorov, Yu.A., Current estimate and a forecast of methane emission by aquatic ecosys tems in European Russia, in Sb. tr. VI Mezhdunar. nauchnoprakt. konf. “Ekologicheskie problemy. Vzglyad v budushchee” (Coll. Papers VI Intern. Sci.Pract. Conf. “Environmental Problems. Looking into the Future”), RostovonDon: Rostizdat, 2010, pp. 72–75. 5. Gar’kusha, D.N., Fedorov, Yu.A., and Tambieva, N.S., Methane emission from soils in Rostov oblast, Arid. Ekosis., vol. 17, no. 4(49), 2011, pp. 44–52. 6. Gar’kusha, D.N., Fedorov, Yu.A., and Khromov, M.I., Methane in the water and bottom sediments of the mouth area of the Severnaya Dvina River (White Sea), Okeanology (Engl. Transl.), 2010, vol. 50, no. 4, pp. 498– 512. 7. Dzyuban, A.N., Organic matter destruction and methane cycle in bottom sediments of inland water bodies, Extended Abstract of Doctoral (Biol.) Disserta tion, St. Petersburg, 2007. 8. Climate changes. A set of information cards on climate change, in United Nations Environmental Program (UNEP). Secretariat of United Nations Framework Con vention on Climate Change (UNFCCC), Moscow: Tsenef, 2003. 9. Kuznetsov, S.I., Saralov, A.E., and Nazina, T.N., Mik robiologicheskie protsessy krugovorota ugleroda i azota v ozerakh (Microbiological Processes of Carbon and Nitrogen Cycle in Lakes), Moscow: Nauka, 1985. WATER RESOURCES
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Translated by G. Krichevets