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Late Pleis to cene and Ho lo cene en vi ron men tal evo lu tion of the Wkra River Val ley near Bielawy Go³uskie (cen tral Po land) re corded in palaeo-ox bow lake de pos its Monika This study aimed to re con struct en vi ron men tal changes in the Wkra River Val ley near Bielawy Go³uskie (cen tral Po land) based on geo chem i cal, palynological and subfossil Cladocera anal y sis of de pos its fill ing a palaeo-ox bow lake. Two sed iment bore holes col lected from the palaeochannel bend (BG-1) and neck (BG-2) in clude full se quences of or ganic de pos its ly ing on clastic de pos its. The lower part of the BG-1 bore hole con tains gyttja that ac cu mu lated dur ing the Youn ger Dryas and the Preboreal, which is cov ered by reed peat of Preboreal and Bo real age. On top of this is al der peat that ac cu mu lated during the At lan tic. The ages of the gyttja and peat were con firmed by both ra dio car bon dat ing and palynological anal y sis. The peats are char ac ter ized by a sig nif i cant con tent of or ganic mat ter, which is rel a tively sta ble over time. This in di cates a low inten sity of me chan i cal de nu da tion in the catch ment, which is sup ported by low con cen tra tions of alu mi num and po tas sium. Cal cium val ues greatly ex ceed these el e ments, sug gest ing that the lake was mainly fed by ground wa ter. Vari a tion in trophic con di tions over time is in di cated by a ver ti cal vari abil ity in the con tent of ni tro gen, as well as by the Cladocera pop u la tion. The strong de com po si tion of peat in the top layer of the mire, and in creased con cen tra tions of phos pho rus and heavy met als, testify to in creas ing hu man ac tiv ity dur ing the most re cent time pe ri ods.

Purpose The studies aimed to reconstruct major phases of litho-morpho-pedogenic processes and past environmental changes in the Baltic coastal zone near Poddąbie (54°37,070′ N, 16°57,897′ E) based on physical, chemical, pollen, and fossil Cladocera analysis of the polycyclic pedocomplex. Materials and methods The polycyclic pedocomplex under study included seven fossil soils developed from the Early Holocene until modern times from various materials. The soils were sampled and analyzed using standard procedures in soil science to determine their physical and chemical properties. Pollen and fossil Cladocera analysis was also carried out in the examined profile. Radiocarbon dates of selected samples were also specified. Results and discussion The studied polycyclic pedocomplex has been developed from materials of varied origin, including glaciofluvial, fluvial, aeolian, and biogenic deposits of the lake. According to the results of pollen and fossil Cladocera analysis and radiocarbon dating, this body of water has evolved from the beginning of Preboreal period to the half of Boreal. The studied soils represent various reference groups and advancement of development. They constitute relics of former geomorphological and soil-forming processes, which have taken place over the last 9500 years, including periglacial processes, wildfires, Baltic Sea shoreline changes, and aeolian activity. The last stage of the coastal relief dynamics was conditioned by the fire which took place about 1472-1637 AD. The lack of plant cover and intensive abrasion due to direct vicinity of the coastline has caused the deposition of aeolian material, which is the parent material of nutrient-poor initial soils. Conclusions The analysis of fossil soil development with the use of specialized research methods allowed for reconstructing the dynamics of past geomorphological processes and natural environment changes in the study area. The studied polycyclic pedocomplex constitutes a record of environmental changes taking place in the central part of the Polish Baltic coastal zone from the Early Holocene to the present day. The studied soil sequence is located within a land depression developed in place of the former water reservoir created as a result of permafrost degradation, and filled with Holocene deposits.