Ecological and geochemical analysis of surface water in the zone of influence of oil production on the territory of Khanty-Mansi autonomous district - Yugra

The study considers the environmental status of surface water bodies located on the territory of Ra-venna license area in the Khanty-Mansi Autono-mous district -Yugra. The research showed that the concentration of ammonium ions in the rivers Su-khmitingyagun and Inguyagun exceeded ACSf (al-lowable concentration of substances in water bodies used for fishing) and was 0.56 and 0.52 mg/dm3 re-spectively. It was found out that the concentration of total iron in all samples of water bodies exceed ACSf from 9.8 to 21.3 times, manganese was from 3 to 5 times, copper was up to 2 times. This situa-tion was characteristic of the West Siberian region and was caused by its climatic conditions; the in-creased maintenance of elements was natural fea-ture of the explored territory and was not consid-ered as pollution. The oil content was close to ACSf (0.05 mg/dm3) in all the water bodies under re-search. The sediments of water bodies were an indicator of water pollution, as substances that were excreted from water mass, accumulated and concentrated in the sediments. The values of oil products in ground sediments of the studied water bodies were 60.4-67.48 mg/kg, which correspond-ed to the characteristic state of benthic ecosystem, i.e. its threshold state, species replacement, a pro-nounced depletion of benthic ecosystems (50- 100 mg/kg).The correlation coefficient of depend-ency on the content of oil products in surface water to the content of oil products in ground deposits was r =0,404 that was direct link of the average closeness. Comparative evaluation showed that the oil content of the sediments was dozens of times higher than those in surface waters due to sorption ability of sediment, as well as self-cleaning ability of water bodies. The results of analysis of surface water samples of rivers Suhmitingyagun, Vo-loktayagun and Inguyagun may be classified as moderately polluted according to water pollution index (WPI = 1.51-1.84), river Yakkunyagun and lake Yakkunlor may be classified as polluted ac-cording to water pollution index (WPI = 2.44-2.49). According to BOD all studied water bodies belong to moderately polluted; according to level they belong to contaminated ones, except the lake Yakkunlor, which can be classified as moderately polluted.