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Krajobraz wyżyn lessowych Polski SE ulega intensywnym przekształceniom antropogenicznym od około 5 tys. lat. Polegały one przede wszystkim na zwiększaniu powierzchni użytkowanych rolniczo. W II połowie XX wieku pojawiła się nowa tendencja w użytkowaniu terenu - wyłączanie spod uprawy stoków o dużej dynamice procesów erozyjnych. Szczegółowymi badaniami objęto rolniczą gminę Wąwolnica, w części pokrytej osadami lessowymi. Intensywność erozji na zboczach określono na 2,0-7,4 mm·rok⁻¹. W ciągu ostatnich 35 lat lesistość na obszarze gminy wzrosła z 7,5 do 12%. Na podstawie analizy zmian pokrycia terenu oraz danych dotyczących dynamiki erozji (metoda wykorzystująca Cs-137) dokonano oceny zmian intensywności procesów erozyjnych. Szacuje się, że ilość materiału przemieszczanego co roku w skali gminy zmniejszyła się o 20-25% (w okresie 1962-1997).
The study presents the geomorphological effects of extreme hydroclimatic phenomena such as violent downpours, widespread rainfalls with a high sum of precipitation, and intensive snowmelt occurring in the eastern part of Polish Uplands between the Vistula and the Bug rivers. The intensity and impact of these phenomena on relief is exceptionally varied here due to the variety of natural conditions as well as the degree and type of land use. These conditions result in the various kinds, formation time and volume of surface runoff as well as the intensity and volume of erosion. The impact of extreme geomorphological processes is particularly pronounced in the case of agriculturally used loess-covered areas with strong relief that cover approx. 30% of the area. In morphological terms, the most effective are the processes of rill erosion in slopewash systems as well as gully erosion processes with the predominance of piping. These processes, along with tillage erosion, determine the development trends of contemporary slope relief in this part of the uplands. In slopewash systems, rainwater runoff causes the movement of material from slopes to valley bottoms that are dissected as a result of snowmelt runoff. In erosion systems (gully systems) during snowmelt, the edges of gullies are dissected (mainly through piping) and their bottoms are covered by sediments that, in turn, are dissected by rainwater runoff. In the valleys of rivers of a low hydrological order, extreme channel processes occur during torrential summer downpours. The bottoms of large valleys are intensively shaped primarily during high water stages caused by snowmelt and rainfall.
The physical and chemical parameters of soils play an important role in the binding and migration of trace elements in the environment. The study attempts to assess the correlation between the basic characteristics of colluvial and alluvial soils and the concentration of Cd, Cu, Pb and Zn. This will make it possible to indicate the key factors determining the binding of metals in soils. The studied soils were located in an agricultural region in Eastern Poland and subjected to generally low anthropogenic pollution. Sixteen profiles (160 samples) were analysed for total heavy metals content and selected soil properties: grain size distribution, soil organic matter (SOM) content, pH, Fe and Mn content. We used three statistical methods: principal component analysis, cluster analyses and Pearson`s correlations coefficient. Relations for colluvial and alluvial soils were different. SOM content was characteristic for the highest positive correlations with the heavy metals. The most distinct correlations with this parameter occur in the case of lead. No correlations with pH were found, the correlations with the particular fraction content were weak. Strong but diversified correlations occurred in the case of Fe and Mn. In general stronger correlations with soil characteristics were found for samples with the low heavy metals content; anthropogenic impact causing the disruption of natural correlations.
Fluvial sediments accumulated in the bottoms of river valleys downstream from large cities are characterised by higher levels of heavy metal content, which poses a threat to the environment and humans. This study presents a comprehensive assessment of the degree of pollution of four alluvial sediment profiles (80 samples), collected from the bottom of the Bystrzyca river valley downstream from Lublin, conducted with the use of five geochemical indices. Channel deposits and sediments (alluvial soils) sampled from the floodplain were analysed. The content levels of the six heavy metals under study were as follows: Cd: 10.6–291.2 mg/kg, Cr: 53.1–292.4 mg/kg, Cu: 20.4–223.1 mg/kg, Ni: 2.9–19.3, Pb: 39.3–280.3, Zn: 108.9–991.4 mg/kg. The horizontal and vertical variation of the pollution level was linked with the history of anthropogenic pressure on the one hand, and the geomorphological location of a given profile on the other. Heavy metal content in the samples did not show any correlation with grain size composition, organic matter content, and Fe and Mn content. Cadmium was the element whose concentration levels were comparable with those in alluvial sediments of rivers in industrialised areas while the indices for the other metals showed varied levels of pollution: from low to high. However, the ecological risk is high for all samples as indicated by the synthetic potential ecological risk index, which takes into account the toxicity of all the metals under study.
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