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.

Quantifying the Impact of Future Climate Change on Runoff in the Amur River Basin Using a Distributed Hydrological Model and CMIP6 GCM Projections

The Amur River is one of the top ten longest rivers in the world, and its hydrological response to future climate change has been rarely investigated. In this study, the outputs of four GCMs in the Coupled Model Intercomparison Project Phase 6 (CMIP6) were corrected and downscaled to drive a distributed hydrological model. Then, the spatial variations of runoff changes under the future climate conditions in the Amur River Basin were quantified. The results suggest that runoffs will tend to increase in the future period (2021–2070) compared with the baseline period (1961–2010), particularly in August and September. Differences were also found among different GCMs and scenarios. The ensemble mean of the GCMs suggests that the basin-averaged annual precipitation will increase by 14.6% and 15.2% under the SSP2-4.5 and SSP5-8.5 scenarios, respectively. The increase in the annual runoff under the SSP2-4.5 scenario (22.5%) is projected to be larger than that under the SSP5-8.5 scenario (19.2%) at the lower reach of the main channel. Future climate changes also tend to enhance the flood peak and flood volume. The findings of this study bring new understandings of the hydrological response to future climate changes and are helpful for water resource management in Eurasia.

Individual tracking reveals first breeding of Oriental Storks at age 2 years in the wild

In this study, we report the first ever documented instances of attempted and successful reproduction (rearing two offspring) of Oriental Storks (Ciconia boyciana) at age 2 years in a wild population in the middle Heilongjiang-Amur River Basin in Russia, using a combination of GPS-GSM tracking, DNA sex identification and field verification.

Intraspecific structure of the Coregonus lavaretus complex in water bodies of Siberia: a case of postglacial allopatric origin of Yukagirian whitefish

The results of morphological and genetic analyses of forms/species of the Coregonus lavaretus pidschian (Gmelin, 1789) complex from the Indigirka and Kolyma river basins are presented in the context of there being recent postglacial speciation events. It has been found that the studied whitefishes belong to the sparsely rakered and low lateral-line forms and have previously been described as Coregonus lavaretus pidschian n. jucagiricus Drjagin (Berg), 1932. Based on these characters, this whitefish does not differ from most Arctic whitefish populations (in particular from Coregonus lavaretus glacialis Kirillov, 1972). Analysis of variability of the ND1 gene (mtDNA) showed that whitefishes from the Indigirka and Kolyma basins belong to a distant phylogenetic lineage, which is significantly different from all previously studied whitefish lineages from the Ob, Yenisei, Lena, Anadyr, and Amur river basins. Analysis of variability of the ITS1 fragment (nDNA) showed that all studied forms/species (from Ob River to Amur River basins), including C. l. pidschian n. jucagiricus, have a tandem arrangement of two identical nucleotide fragments and very similar nucleotide composition of the ITS1 region. Based on contemporary data, this phylogenetic lineage of the C. pidschian complex could be considered a young postglacial allopatric species.

Impact assessment of solid runoff on heavy metals migration during high floods on the Amur river

Inhomogeneity of the concentrations of chemical elements in the cross-section of the Amur River is considered as a function of the state of their soluble and suspended forms. Flooding of wetlands and urbanized areas contributes to the removal of pollutants into the river channel. The wide spread of fens on the left bank contributes to the concentration of organic matter along the left bank of the river. Terrigenous material mostly comes from the right bank, where agricultural fields are concentrated. The ratio of their concentrations is maintained by the duration of the flood. The mechanisms of redistribution of elements between their suspended and soluble forms have been studied. The mechanisms of sorption of chemical compounds on mineral and organic colloids are described. It was found that mineral colloids with a negative charge due to electrostatic attraction sorb electrically neutral compounds (hydroxoaqua complexes [Mn(OH)2(OH2]0, ammonia [Cu(NH3)4(OH)2]0. The role of organic material in the redistribution of chemical compounds between soluble and suspended forms is shown. Organic colloids with molecular mass > 5.0 kDa precipitate complex cations – [FeHSO4]+, [FeHSO4]2+, [CuHSO4]+. An organic substance with a molecular mass of <2.0 kDa has a greater complexing ability for Fe(2)3+, Cu2+, Zn2+, Mn2+ ions. They bind metals to organo-mineral complexes by chemical interaction and form mobile organo-mineral complexes and heteropolar salts.

Bioindication of mercury pollution of the Amur River during the ice-covered period

The results of the layer-by-layer research of a river ice cores by using spectral and microbiological methods were presented. The impact of the mercury on sulfate-reducing bacteria activity from different layers of ice that had been sampled in March 2016 in the lower Amur River in Khabarovsk city was found. It was found that mercury concentration range of 0.0005-0.001 mg/l stimulated the sulfate-reducing bacteria activity, which were into the ice throughout the study area of the Amur River. To a large extent, this effect was typical for the ice that was sampled in the right bank of the Amur River near Khabarovsk city, where mercury pollution of the aquatic environment had been detected repeatedly. The activity of biogeochemical processes into the ice determined by high concentrations of organic substances, by the pollution of the aquatic environment with mercury during the ice cover formation, and by the abundance of cultivated heterotrophic and sulfate-reducing bacteria. During the ice drift and ice melting, the secondary pollution with toxic substances of various genesis of the aquatic environment occurs, which can have a negative impact on a hydrobionts.