Geochemical Analysis and Biotesting of Natural and Anthropogenic Oilfield Substance Inputs into a Small River Within a Karst Region

Aim . To study the effects of substances entering a small river in a karst region from the secondary accumulation zone of technogenic hydrocarbons. Methodology . Technogenesis in a karst region was studied using a set of chemical-analytical methods for determining the composition of water and bottom sediments, and biotesting using a test object of chlorella algae culture ( Chlorella vulgaris Beijer). Spatial analysis and statistical processing of the obtained data were carried out. Results . Groups of substances by distribution of chemical elements in a cascade of manmade ponds of a small river in a karst region have been identified. Sr, As, Zn, Ni accumulate in ponds. Co, Fe, Cr, V, Ti accumulate in watercourses. Mn is uniformly distributed. Pb is abnormally concentrated in one area. The toxicity of the source of man-made pollution in the upper reaches of the river has been proven. It has been established that a cascade of ponds built on a small river can reduce toxic impact by 1.5 times. The dependence of the results of geochemical analysis and biotesting is complex, nonlinear, and inverse, indicating the correctness of using both methods to assess water toxicity. Chemical elements (As, Pb, Sr, V) for which it is necessary to organise monitoring as part of industrial control are recommended. Research implications . A comprehensive assessment of the influx of technogenic hydrocarbon substances on the state of the natural environment in a karst region is given. The nature of the dependence of the results of geochemical analysis and biotesting is revealed. Recommendations for further industrial control are proposed.