Julita Tomkowiak

Kopanicha peatland is located in western part of the Rawka river valley, near Skierniewice. In order to reconstruct the main stages of sedimentation of organic deposits, taken from the central part of the Kopanicha peatlands, used stratigraphic variability of concentration marked lithogeochemistry elements (organic matter, mineral matter, macro- and microelements) and erosion index (Na+Mg+K/Ca), eutrophication index (Fe/Ca), type and rate of denudation in the catchment index (Na/K, Ca/Mg) and redox index (Cu/Zn, Fe/Mn).

Peat development in the oxbow lake complex occurred at the beginning of the Atlantic period, and peat growth lasted until the modern times, but with clear interruptions in the Atlantic and Subatlantic (Forysiak 2012).

As a result of the hierarchical cluster analysis seven geochemical zones (Kop1/I-VII ) were selected. These zones differ significantly of chemical composition. The main component of studied sediment is organic matter (84.6–95.5%), which indicates the relative changes in the primary of biological production in wetlands. The average content of the tested components have the low differentiation between all geochemical levels, constitute a record of stable environmental conditions (mainly hydrological and geomorphological). Sediments of geochemical level Kop-1/I are characterized by the high content of mineral matter and higher rates of mechanical denudation and erosion rate of the catchment. Geochemical levels Kop-1/II and Kop-1/III provide the record of sedentation autochtonous rock-forming matter of autogenic origin (increase content of organic matter to 95.5% and associated change of mechanical denudation and redox conditions (decrease of lithogenic elements and Fe/Mn ratio). Geochemical levels Kop1/IV represents the phase of alder swamp peat layer deposition in reduced conditions (increased Fe/Mn ratio to 80.8) and increased chemical denudation (Ca/Mg ratio ranges from 32.6 to 69.2). Geochemical level Kop-1/V records sedentation of autochtonous rock-forming matter of autogenic origin (organic matter ranges from 90.2% to 91.6%) and associated change of mechanical denudation (first increase catchment erosion indicator to 0.88 and then decrease to 0.78) and redox conditions (first increase conditions of oxidation-reduction indicator to 96.4 then decrease to 62.8). Their sedimentation took place both in stagnant ground waters, as well as during periodic floods. Geochemical level Kop-1/VI represents of peat layer, which sedentation occurred in periodic of drying bed. The content of organic matter decreased to about 90% and Fe/Mn ratio decreased to 39, indicates the change of reduced into oxidized conditions. Geochemical level Kop-1/VII is the record change type of sedentation of peat on muck, as is also indicated by abrupt decrease of organic matter (from 93.7 to 88.8%), decrease of Fe/Mn ratio (to 26.7) and increase in catchment erosion indicator (from 0.6 to 0.74).

The most important factors (distinguished on the basis of principal components analysis) that affect the chemical composition of sediments from the site Kopanicha are: sorption of organic deposits, oxygenation changes in sedimentary environment, which are mainly due to the flooding of the Rawka river

Bęczkowice peatland is located in central part of the river valley Luciąża, near Kamieńsk. In order to reconstruct the main stages of sedimentation of organic deposits, taken from the southern part of the Bęczkowice peatlands, used stratigraphic variability of concentration marked lithogeochemistry elements (organic matter, mineral matter, macro- and microelements) and changes in the proportions of the participation of selected elements, i.e., catchment erosion indicator (Na+Mg+K/Ca), eutrophication indicator (Fe/Ca), type and rate of denudation in the catchment indicator (Na/K, Ca/Mg) and conditions of oxidation-reduction indicator (Cu/Zn, Fe/Mn).

Peat sedentation was interrupted at the beginning of the Atlantic. The peatland developed again in the Subatlantic (Forysiak 2012).

As a results of the hierarchical cluster analysis was collected in the study profile of six geochemical level (B-1/I–VI), which differ significantly of chemical composition. The main lithogeochemistry component of studied sediment is organic matter (42.4–93.2%), which indicates the relative changes in the primary of biological production in wetlands. The average content of the several tested components (for example: mineral matter, lithophilic and sulfophilic elements) have the low differentiation between all geochemical levels, constitute a record stable of environmental conditions (mainly geomorphological and hydrological). Sediments of geochemical level B-1/I represents the phase of mineral and mineral with a small amount organic matter layer in reduced conditions (increase Fe/Mn ratio to 313) and increased mechanical denudation (catchment erosion indicator ranges from 2.58 to 3.1 and type of denudation in the catchment indicator – Na/K ranges from 0.07 to 0.10). Geochemical level B-1/II are characterized by gradual increase of organic matter content (from 18.3 to 66.2%) and slow increase type of denudation in the catchment indicator: Na/K (from 0.07 to 0.09) in the clay limnic deposits. Geochemical levels B-1/III are the record of sedentation autochthonous rock-forming matter of autogenic origin (average content of organic matter is 72.2%) and rapid change of redox conditions (decrease of Fe/Mn ratio from 1036 to 358). Geochemical levels B-1/IV represents the phase mainly of sedge-moss peat and reed peat layers deposition in oxygenated conditions in sedimentary environment (average Fe/Mn ratio is 63.1) and gradual increase rate of chemical denudation (Na/K ratio ranges from 0.6 to 1.95). Geochemical level B-1/V is record of sedentation of autochthonous rock-forming matter of autogenic origin (organic matter ranges from 69.3% to 91.9%) and significant increase of mechanical denudation in the catchment (average of
catchment erosion indicator increased to 0,36). Geochemical level B-1/VI is the record change type of sedentation of peat on muck, as is also indicated by abrupt decrease of organic matter (to 80%), decrease of Fe/Mn ratio (to 51) and increase catchment erosion indicator (from 0.14 to 0.67).

The most important factors (distinguished on the basis of principal components analysis) that affect the chemical composition of sediments from the site Bęczkowice are: biological productivity in wetland’s  ecosystem, mechanical and chemical denudation processes in the catchment (eg. the supply of allochtonous mineral matter), sorption of organic deposits, increase of the rainwater in the water balance and anthropogenic activity.