Characteristics of the macro - and microelements in benthic sediments of selected mid-field ponds

The agricultural landscape of Western Pomerania is characterised by frequent occurrence of small, post-glacial water ponds commonly called mid-field ponds. They serve numerous important functions, both with regard to agriculture and ecology. Due to their specific location in the agricultural landscape, they are exposed to permanent and strong anthropic pressure, which often translates into pollution of surface water and benthic sediments with macro-and microelements. This study attempts to assess and determine the level of macro – and microelements in benthic sediments, depending on the type of agricultural production, on the example of selected mid-field ponds. The assessed benthic sediments of both ponds were characterised by varied macro - and microelement levels, depending on the collection site and the depth of their deposition. Based on the performed chemical analyses it was found that both observation points in the pond Żelisławiec were characterised by the highest concentrations occurring in the top layer (0-5 cm), which is related to the fact that there are areas of agriculture in the pond basin with the use of mineral and organic fertilisation and occurrence of higher water erosion. And the other assessed mid-field pond (Stare Czarnowo) showed the highest concentration of microelements in the middle layer, 5-15 cm. Statistical analyses revealed that statistically significant differences were observed only for potassium levels, depending on the type of agricultural production in the basin of both assessed ponds. This may result from various types of agricultural crops (Brassica napus L. var. napus and ×Triticosecale Wittm. ex A.Camus) and intense fertilization of arable land in Stare Czarnowo. Statistically significant differences in particular layers of sediment confirm that depending on the type of agricultural activity, mid-field ponds are supplied with various mineral matter at different times, resulting in its accumulation in benthic sediments.