Quantitative characteristics of zooplankton in the rivers of the Upper Amur Basin, exposed to the effects of placer gold mining

Research conducted in June and September 2020 showed that the species composition of rotifers and lower crustaceans in 17 water courses of the Upper Amur Basin, exposed to the effects of placer gold mining, included 43 species. Most of the water courses were researched for the first time. Based on the environmental and geographic assessment, the prevalent species were widespread and eurytopic. Most parts of the rivers were characterised by low quantitative characteristics (0.01–3.77 × 103 ind. m-3 and 0.06–54.64 mg m-3), which was explained by the hygrological conditions and long-term effects of mining in the river beds. A better productivity (up to 39 × 103 ind. m-3 and 228 mg m-3) was registered in the areas of former excavations in the river beds, with slower water exchange and better conditions for the development of zooplankton.

The impact of the placer gold mining in Eastern Transbaikalia (Russia) on the environment components of river valleys in the Amur River basin

Based on the results of the analysis of satellite images and field observations, data on the length of the gold-bearing placers disturbed by the development along a number of main tributaries of the Shilka and Argun rivers are presented, the formed technogenic relief forms are indicated. Depending on the method of development, two types of technogenic landscapes have been identified - the excavation-dump with hydromonitor mining and belt trench-dump when washing with drags. The main directions of research on the assessment of placer gold mining in the natural complexes of river valleys are proposed.

Current state and main directions of innovative development of placer gold mining in Far East Federal District

Based on the assessment of the resource base of Far East region of Russia, the important role of the mining industry for most regions of Far East Federal District was noted. A decrease in the resource potential of geogenous placers has been established, therefore anthropogenic deposits of placer deposits become an important reserve of placer gold mining. Natural and technological factors that need to be taken into account when selecting and applying those technologies and mining equipment that can reduce their influence are as follows: permafrost rocks, high clayey sand deposits, large content of fine and fine fractions of gold, the presence of high content of heavy fractions of other valuable passing components, etc. A number of developed innovative technologies for development of alluvial deposits, as well as new technological equipment for use on dredges and drags, have been noted. The parameters of the technological processes of the jigging machine on the Alaska-35 washing device (USA) have been analyzed, the matrix of interacting factors (such as the shape of the particles of a mineral, particle size, particle density, height of the bed of the jigging machine, frequency of piston swings, stroke of piston, etc.), the purpose of the study is to obtain graph-analytical dependencies for calculating their rational parameters that ensure effective extraction of metals.