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An estimation of sedimentation rate of suspended matter was done in beaver (Castor fiber) ponds and oxbows of the River Khoper valley (State Nature Reserve «Privolzhskaya Lesostep'», Penza region, Russia). In beaver ponds the sedimentation rate varied from 7.33 g/m2 per day to 71.81 g/m2 per day, in oxbows – from 7.83 g/m2 per day to 10.69 g/m2 per day. The share of the mineral part was different in different water bodies. In beaver ponds organic matter formed 39.93–56.12%, in oxbows – 77.11–81.29%. The organic percentage showed that long existence and stability of oxbows lead to a higher biodiversity and biomass of flora and fauna. The rate values could depend on some factors that beavers influence on. We used six parameters for the estimations of the beaver impact: location of water body, abundance of animals, building activities, area of flooded valley, digging activities, input of woody material. Mainly, their building activities and area of flooded valleys increased sedimentations and decreased the share of organic matter. Also, we suggest that amounts of suspended matter could depend on vegetation (woody or grasslands), age of beaver settlements, and other zoogenic activities. Beaver ponds could accumulate less volume of sediments, because they are situated on small rivers and have less size and watershed area than oxbows, and existed not so long as natural water bodies. The chemical composition of sediment was studied with the X-ray fluorescence spectroscopy. The chemical compound of suspended matter was connected with the composition of watershed. So, maximum concentrations were observed for iron, silicon and calcium. Some concentrations indicated anthropogenic fertilisation (phosphorus, chlorine, potassium) and technogenic pollution (zinc, copper, lead, arsenic). Our results suggest a possible beaver impact on concentrations of phosphorus (inflow from burrows) and zinc (input with branches and twigs). The study confirms the importance of beaver ponds for accumulation of pollutants and ecosystem purification. |
