Recovery Of Aquatic Invertebrate Communities As A Result Of Oil Decontamination Of Bottom Sediments
Yu. A. Noskov, D. S. Vorobiev
Oil decontamination of water bodies is one of the most complex and time-consuming tasks in the field of liquidation of oil spills. The complexity of cleaning natural water bodies is associated with a dynamic water environment and a variety of oil transformation processes that occur in the water. The most advanced and developed are technologies and methods of collecting oil and oil products from the surface of water bodies. Economically acceptable and well-grounded technologies for oil decontamination of bottom sediments are presented in minimal quantities, and often are not applicable to natural water bodies. The technology for oil decontamination based on flotation has been developed and successfully applied on Lake Shchuch'ye in 2004–2005 and showed a positive result after two summer seasons of work. This article presents the results of aquatic ecosystems recoverу as a result of oil decontamination of bottom sediments. The issue of restoration of the aquatic ecosystem as a result of cleaning bottom sediments from oil after a considerable time interval has been studied. A comparison of the quantitative indices and species diversity of the zooplankton of Shchuch'ye Lake from 2004 to 2016 showed a clear tendency of increasing the abundance, biomass and species diversity of total zooplankton and Cladocera in particular. In 2016 the amount of zooplankton species of Shchuch’ye Lake reaches the number of species of the uncontaminated lake, using as a control. It was shown that the macrozoobenthic fauna of Shchuch'ye Lake is poorer in both the number of main ecological groups and in species diversity within certain groups characteristic than in the uncontaminated lake. Some groups were found in both lakes, but the species diversity of Lake Shchuchye was poorer. The exception was a group of leeches, which had a greater variety in Lake Shchuch'ye. The change in the oligochaetene complex to chironomid, both in numbers and in biomass, indicates an improvement in environmental conditions, since chironomids are more sensitive to the quality of the habitat. Chemical analysis of bottom sediments in 2016 revealed that the oil concentration did not exceed 0.9 mg / kg, which indicates the effectiveness of the oil decontamination technology of bottom sediments.