Contribution Of The Different Sources To The Formation Of Alluvial Sediments In The Selenga River Delta. (Eastern Siberia, Russia)

Abstract

Unraveling sources of sediment supply, their temporal and spatial variability is of key importance to determine origin of deposits and to explore the formation mechanism of Selenga Delta landscape units. From an environmental point of view this solution would help to identify the particle-bound pollution sources. We used geochemical fingerprinting (the FingerPro R package), which is a modern quantitative implementation of the method of sedimentary provenance analysis. The main aim was to recognize the main patterns of sediment and associated particle-bound pollutants transport and deposition within the delta. At the old floodplain from 55% to 90% of sediments were delivered from the eroded floodplain and terrace banks upstream and only about 10-15% originates from the remote basin sources. Sedimentary environment in the Khlystov Zaton reveals a greater variety than on the floodplains. 40% of sediments from the upper 5 cm-layer originated from the flood, taking place in 2013, and 30% were the product of floodplain and terraces banks erosion. Nevertheless, analysis of the fine-grained component of suspended sediment sets the material from eroded floodplain banks as the dominant source of accumulation within the delta. This means that the self-absorption is the leading process in the Selenga delta at the moment. Heavy metals and metalloids accumulates in the lower reaches of the Selenga on the floodplain surface, deltaic lakes and oxbows during high floods. Runoff decrease during floods can lead to the release of pollutants into the Lake Baikal.

Phthalates in Surface Waters of the Selenga River (Main Tributary of Lake Baikal) and Its Delta: Spatial-Temporal Distribution and Environmental Risk Assessment

“…To assess the quality of water and phthalate content in the Selenga River and its delta, samples of surface water (n = 118) were taken from a depth of 0.2-0.5 m at the following sampling sites: in the Selenga River [upstream of Ulan-Ude (1); downstream of Ulan-Ude, at the right (2) and left (3) banks of the Selenga River; at the beginning of the delta-a point downstream of Kabansk (4)], and in the estuarine areas of the Selenga River [Levoberezhnaya (5), Kharauz (6), Galutai (7), Srednyaya (8), Severnaya (9), Lobanovskaya (10)] (Figure 1).…”

“…The river water enters Lake Baikal with a significant amount of dissolved and suspended terrigenous material. This material is mostly deposited at the river mouth, forming a classic delta with an area of approximately 600 km 2 [7,8]. The floodplain and soils in the riverine areas, together with the associated aboveground and aquatic vegetation, serve as a geochemical barrier safeguarding the waters of Lake Baikal.…”

Large Rivers Hydrology And Sediment Transport

“…Therefore the knowledge of sediment origin can be crucial for sustainable management planning (Walling 2005). The research by Zaharova and Belyaev (2022) was conducted using the geochemical fingerprinting method, which uses a quantitative approach to determine sediment origin and associated pollution. Using this method, they found that the majority of sediment on the floodplains of the delta was sourced from floodplains and terraces slopes, and only a small amount originated from remote areas.…”