| Abstract [eng] |
The amount of sewage sludge (SS) is continuously increasing, posing challenges for its utilization. SS is primarily applied in agriculture and landfilling, but its benefits for soil due to high organic matter and essential nutrients are countered by its pollutant content, including heavy metals (HM), organic pollutants and other toxic substances. Current SS application regulations only focus on HM and nutrient levels, overlooking risks to soil biota and ecosystem functions. Climate change alters the dynamics of pollutants, affecting their dispersion, bioavailability, and impact on soil organisms. Consequently, SS fertiliza tion rates must be adjusted with ongoing climate change. Earthworms are widely recognized as model organisms for assessing soil toxicity due to their ecological significance, sensitivity to contaminants and reliability as indicators of soil health. Adverse impacts of SS on earthworms can impair ecosystem functions, leading to diminished soil fertility and biodiversity. Understanding how increasing temperature and altered soil moisture will change SS impact on soil dwelling biota is critical for SS management and reuse in agriculture and forestry. This study aimed to analyze the single and combined effects of air temperature (21 and 25ºC) and soil water content (SWC optimal, reduced, and elevated) to earthworm Eisenia fetida in SS amended soil (0-50 t/ha). Growth and mortality were measured weekly, and oxidative stress was assessed at the end of the experiment using biochemical indicators such as superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA). The results showed that E. fetida is tolerant to low HM mixture pollution in SSamended soil under changing climate conditions. Lowest SS doses (12.5 and 25 t/ha) promoted growth at optimal SWC, while the highest SS dose (50 t/ha) caused the biggest mortality in all analyzed SWC levels. The earthworm s antioxidant system, crucial for metal detoxification, played a key role in mitigating toxic effects. Elevated temperature (25ºC) intensified the harmful impact of HM across all SWC levels. Controlling environmental conditions (temperature, substrate compatibility, etc.) and pollutant levels is crucial to soil organisms. This study provides insights into the interactions between climate factors, pollutant toxicity, and soil organisms, offering valuable implications for future bioremediation efforts and the use of SS as fertilizer. |
