Ecological implications of boron and sulfur in sediments from a lake in the Nile Delta: Remote sensing, fractionation and ecotoxicity

Abstract

Abstract Purpose The study aimed to provide an overview of the behavior, fate and ecotoxicity of boron and sulfur in the sediments of Lake Burullus, Egypt, after the degradation of the lake area. Materials and methods Changes in the studied lake area due to human activities were estimated using Erdas Imagine v14 and ArcGIS. Sequential and non-sequential extraction techniques for boron and sulfur fractionation in sediments were evaluated. Results and discussion A remote-sensing tracking investigation revealed a decrease in area of about 19.4%. Boron geochemical fractions had the order of residual (BF5, 61.48 ± 3.84%) > bound oxide (BF3, 15.47 ± 9.64%) > specifically adsorbed (BF2, 13.34 ± 9.85%) > bound organic (BF4, 9.85 ± 12.40%) > water-soluble and exchangeable (BF1, 2.2 ± 2.66%). Sulfur gave the order of the fractions as residual (SF5, 70.52 ± 16.92%) > phosphate extractable (SF2, 15.47 ± 9.34%) > bound organic (SF4, 7.20 ± 5.35%) > CaCl2 -extractable (SF3, 9.85 ± 12.40%) > water-soluble sulfur (SF1, 1.34 ± 1.52%). A worst-case scenario involving boron and sulfur toxicity values was studied using mixture risk characterization ratios (RCRmix) based on the predicted no effect concentration (PNEC) and sum of toxic units (STU). Conclusions The RCRmix and STU of boron showed high long-term risks to aquatic organisms, while sulfur showed high short-term risks. Invertebrates were the most sensitive species to boron and sulfur. This study sheds light on the ecological impact of boron and sulfur in Lake Burullus sediments, highlighting potential risks to aquatic organisms. Further research could focus on developing mitigation strategies to address these concerns. Graphical Abstract