Geochemical features of ombrotrophic bogs and transitional mires under influence of drilling waste pits
Drilling waste pits are considerable environmental threat to oilfields in Ugra region (Western Siberia). Drilling wastes kept in the pits lead to chemical pollution of oilfields. In this research, we investigated adjacent areas to seven drilling waste pits. The concentrations of macro-, micro- and rare earth elements was investigated in pristine bog peat of middle taiga zone in Priobie region and the results were compared with the available reference data and clarkes for bogs. The concentrations of macro- and microelements in peat in pristine areas of oilfields in Surgutskoe Polesie is higher than in similar areas of Samotlor oilfield. Drilling waste pits lead to increase in content of all investigated macro- and microelements in peat. Amongst macroelements Cl, K, Mg and Fe most actively accumulate in peat of disturbed areas and Br, Sr, Ni, Rb are the most active amongst microelements. Microelements accumulate in upper peat layer while the accumulation of macroelements is more specific. Drilling waste pits lead to 1-3 unit increase of pH of peat water suspension, three times increase of ash content in peat, seven times increase of electrocondactivity of peat water suspension. The influence of drilling waste pits is stronger on Samotlor oilfield compared to Surgutskoe Polesie oilfields. The reason for that could be the differences in histories of oilfield development. Generally, drilling waste pits considerably change geochemical conditions of bogs and provide conditions for meso and eutrophic vegetation establishment.