Chemical composition of natural waters on the atomic power station building site (Tomsk region, Russia)

Naymushina O.S.

Institute of natural resources, Tomsk Polytechnic University, Tomsk, Russia

olgnaim@mail.ru

In connection with the large atomic enterprise placing, planned in northern part of Tomsk, Russia, there exists a necessity of a problem-solving of its drinking and technical water delivery. Therefore data on a chemical composition of natural waters is one of evaluation stages of a geochemical condition of the territory.

The territory of Seversk’ atomic power station building is situated in the right-bank part of the Tom river undercurrent valley within the bounds of the second terrace above the flood-plain. Two relatively small swamps – Klyukvennoe and Tyomnoe - are located here, which are poorly drained. Four small rivers (Shishkoboika, Mostovka, Chernaya, and Kamyshka) flow in this area, but their discharge in the summer time is only 0.8 – 4.9 l/sec in the mouthpart. In those places where the swamps frequently occur these rivers get lost and are impossible to be found among hummocks and bushes, i.e. water exchange in these areas according to our data is negligible [1].

Deposits underlying swampy-lake sediments are represented by Oligocene-Quaternary argillo-arenaceous units with lavishly spread groundwater. Top of these deposits is built by thin (2 – 3 m) soft-permeable sandy clays, which serve as an underlying bed (though weak) for swamp waters, forming the perched water. Below sandy clays there mainly lie sand and gravel-pebble alluvial deposits with interbeds of clays and sandy clays, irregularly spread over the territory. Grittiness of the section is high, reaching in places 90 – 95%. Sand composition is quartz-feldspathic showing its weathering (authegene kaolinite). All this determines considerably high water abundance of these deposits: hydraulic conductivity values vary from 0.5 to 14 m/d, specific discharge of well runs up to 0.03-35 l/sec, transmissivity rate reaches 400 m²/d.

Gently hilly (horseback) relief, extensive atmospheric precipitates, insignificant evaporation, shallow bedding (4-6 m) of groundwater, and the presence of hydraulic connection between swampy and ground waters contribute to swampy areas. Specifically, bogginess is confined to the areas of occurrence of relatively soft-permeable sandy clays, occupying the lower parts. It is important to note, that there is hydraulic connection between swampy and ground waters.

Chemical components	Swamp waters			Small rivers			Lake water	Short holes
	min	max	av.	min	max	av.		min	max	av.
рH	4,7	5,9	5,2	7,5	7,8	7,7	5,5	3,9	7,2	5,4
HCO3-	6,1	67,2	24,2	160,0	215,0	194,4	3,7	<3	238,0	70,8
CO2 libre	24,9	123,2	65,8	1,8	7,0	4,8	2,6	17,6	57,2	33,5
NH3	1,2	5,0	2,9	0,3	0,6	0,5	0,96	5,1	13,4	8,7
NO2-	<0,01	0,2	0,1	<0,01	0,04	0,02	0,03	0,1	0,3	0,2
NO3-	0,6	1,4	1,2	<0,5	15,6	8,6	0,6	0,6	1,4	1,1
SO42-	<2	<2	<2	<2	7,4	4,7	<2	<2	3,4	2,7
Cl-	2,7	6,0	3,9	1,4	8,0	4,8	0,4	0,4	5,8	1,9
Ca2+	1,6	22,0	7,7	40,0	60,0	52,0	2,0	9,0	13,8	11,2
Mg2+	0,5	8,5	2,7	2,4	7,3	5,5	0,6	2,4	2,9	2,7
Na+	0,5	6,1	2,1	5,0	16,8	10,8	0,4	0,5	4,6	1,3
K+	1,3	5,2	2,6	0,3	2,1	1,3	0,2	0,2	6,8	2,1
Fe total	4,0	22,5	8,9	1,9	8,8	5,2	0,5	1,4	3,6	2,4
Si	3,0	10,2	7,5	6,3	9,8	8,2	1,3	6,0	11,6	7,5
TDS	17,0	101,0	43,2	214,0	296,0	272,3	7,0	18,0	414,0	105,6
Fulvic acids	0,0	126,0	65,0	25,0	69,5	47,8	15,3	82,4	129,3	103,5
Humic acids	6,3	178,5	54,0	3,0	8,4	5,2	1,1	6,0	18,6	11,7
Corg.	12,0	57,1	29,4	-	-	-	19,9	50,8	73,4	63,5

Table. Average chemical composition of natural waters of the investigated area, mg/l

The water samples were taken in August - November 2011. A total of 19 samples were taken including 9 samples directly from swamp, 5 – from various depths in boreholes drilled in peat deposits, 4 – from small rivers, and 1 – from lake.

The findings demonstrate (Table) that all waters (including groundwaters) are ultra-fresh and fresh (general TDS varies from 7 to 400 mg/l), subacid and perineutral, rarer - acidic (рН comes to 3,9-7,8), Ca-HCO₃ or Ca-Na-HCO₃, seldom Ca-Mg-HCO₃ and have a high content of Fe (up to 22,5 mg/l). The most fresh are lake and swampy waters, the average TDS of which is only 7 and 43,2 mg/l, respectively. The most mineralized are river waters, with an average salinity of 272 and a maximum exceeds groundwater - 400 mg/l. рН values act similarly: the most acid are the peat deposit waters (the minimum value of рН is 3,9), the less acid – river waters (рН 7,7).

The levels of chlorine- and sulphate-ions are low (less than 10 and 8 mg/l respectively). NO₃ and NH₃ content, on the contrary, is somewhat higher in relation to normal fresh waters [2]. Specific behavior of Fe consists in the fact that its levels are high in all type of waters starting from swampy ones apart from lake water. It is in the swamp water where they reach the value of 85 mg/l. This situation is accompanied by a low Eh value of the waters, and, as is shown below, by a very high content of organic matter in them.

Somewhat different behavior is typical of NH₃, which reflects the biogenic character of the element, as well as its close relation to biochemical processes. Its contents are higher in swamp waters and groundwater.

The greatest difference of investigated waters consists in the high content of organic matter in them, which exceeds the content of mineral salts.

References:

1. O.S. Naymushina, S.L. Shvartsev, M.A. Zdvizhkov, A. El-Shinawi. Chemical characteristics of swamp waters: a case study in the Tom River basin, Russia//Proceedings of the 13^th international conference on water-rock interaction, WRI-13, Guanajuato, Mexico, 16-20 August 2010.-CRC Press/Balkema, 2010. – p.955-958 (ISBN: 0-415-60426-0)

2. Shvartsev, S. L. 2008. Geochemistry of fresh groundwater in the main landscape zones of the Earth. Geochemistry International 46 (13): 1285-1398.