Аннотация:Urban settlements are often situated in river valleys. This applies to Moscow which is one of the World’s most urbanized areasThe valleys occupy about 40% of total city area and floodplains take up about 10% of this. These floodplains are partly submerged even though runoff is regulated, and riverbeds are enclosed behind barriers. Human impact has been considerable in these floodplain landscapes over many centuries and has involved ploughing, compaction, construction of embankments as well as acting as a repository for waste.
Soil features have changed with human impact. pH shifted from subacid to neutral or alkaline (8 or more) and the contents of major plant nutrients increased. In particular, available phosphorus is up to 20 mg /100g (citric acid extractable P2O5) and organic carbon is 2-6%. This has resulted from using fertilizers, peat compost, domestic animal excrement and other organic waste. In addition there is a noticeable amount of technogenic inclusions (urban & industrial products) in these floodplain soils and some of them produce carbonates, which are unusual for natural alluvial soils in this region. In particular, formerly waterlogged alluvial soils have changed considerably.
With urbanization the modified floodplain soils begin to assume feature of other soils especially those soils that are less well drained. This occurs via the input of new materials very different from natural materials as well as changes in soil thickness by aggradation and excavation. As a result, local conditions are conducive to the formation of specific mineral pedofeatures which can serve as a marker for new genetic horizons reflecting urbopedogenesis.