Quality of Bottom Sediments of Sołtmany Lake (Masurian Lake District, Poland) in the Light of Geochemical and Ecotoxicological Criteria—Case Study

Abstract

The quality of bottom sediment is important for the condition of aquatic environments. High levels of potentially harmful components in sediments negatively affect the quality of surface water environments. Lake bottom sediments are commonly used to control the quality of the environment in terms of both heavy metals and harmful organic compounds. This paper presents new data on the compositions of bottom sediments from Sołtmany Lake, located in the Masurian Lake District (Poland). The aim of this study was to determine the physicochemical properties of bottom sediments and to assess their quality based on geochemical and ecotoxicological criteria. The field study was conducted in July 2021. Thirty sediment samples were collected for analysis from six study sites located in the upper central and lower part of the reservoir. Contamination of the bottom sediments with trace metals was determined on the basis of the geoaccumulation index (Igeo), while an ecological risk assessment was carried out on the basis of calculated values of TEC (Threshold Effect Concentration) and PEC (Probable Effect Concentration) indices. The study shows that the concentration of trace metals in sediments was characterised by slight variation and that the maximum values did not exceed: 1.1 mg·kg−1 for Cd, 8.7 mg·kg−1 for Cr, 10.9 mg·kg−1 for Cu, 7.7 mg·kg−1 for Ni, 12.9 mg·kg−1 for Pb and 52.3 mg·kg−1 for Zn. The analyses further showed that the concentration of trace elements in the sediment surface layer increased in the following order: Zn > Pb > Cu > Ni > Cr > Cd. The maximum pH value of H2O was 7.1, while that of KCl was 7.0. The maximum values of Corg, Ntot, P2O5, K2O and Mg were, respectively: 6.1 g·kg−1, 1.4 g·kg−1, 40.2 mg·100 g−1, 31.2 mg·100 g−1 and 35.1 mg·100 g−1. The assessment of the degree of lake pollution is essential for the conservation of biodiversity and the organisation of environmental management activities.

Pollution and Potential Ecological Risk Evaluation of Heavy Metals in the Bottom Sediments: A Case Study of Eutrophic Bukwałd Lake Located in an Agricultural Catchment

“…The differences in the content of individual trace metals in the studied bottom sediments are undoubtedly influenced by different hydrodynamic conditions of water flow in the reservoir, as well as by the intensity of runoff from the immediate catchment area of the reservoir (the southern part of the catchment area is predominantly farmland). According to many authors [8,[38][39][40], phosphorus and compound fertilizers used in agriculture can be a significant source of trace metals (Cd, Cu, Ni, Pb, and Zn) in soil sediments in agricultural and peri-urban areas. Such a relationship was observed in the case of the studied Bukwałd Lake, where higher concentrations of trace metals were observed in sediments collected on the side of the catchment used as farmland than on the side of the catchment used in other ways.…”

“…To assess the degree of contamination of bottom sediments with metals, many authors use geochemical criteria in relation to the geochemical background, i.e., the content of elements present in the sediments under natural conditions (geochemical index and contamination factor) [23,38,53]. The obtained values of the enrichment coefficient Igeo and CF for selected trace metals accumulated in the bottom sediments of the studied lake indicate natural (weathering of the rock material) and anthropogenic (inflow of pollutants from the agricultural catchment) sources of the identified elements [41,52,54].…”