مشخصات پژوهش

The remediation and sustainable management of metal-contaminated sediments in arid-region water reservoirs are increasingly critical. This study presents a comprehensive environmental assessment of sediment contamination in the Chahnimeh reservoirs, a vital water source in Iran’s drought-prone Sistan region. This research employs an integrated strategy that uniquely amalgamates multivariate statistical analysis, spatial distribution mapping, pollution and ecological risk indices, and life cycle assessment (LCA) to delineate contamination levels and assess sustainable sediment reuse alternatives. Results revealed substantial contamination, especially from Hg, Co, and Zn, with Chahnimeh 1, and the inlet intake identified as major hotspots. Elevated Hg levels were linked to anthropogenic inputs, particularly fertilizers and domestic wastewater. Although several metals exceeded the sediment quality thresholds, Hg exhibited the highest enrichment relative to the background values (pollution load index ≥ 1). The LCA results indicated notable environmental burdens, with 1 kg of sediment contributing 9–12.38 kg 1,4-DB eq. to human toxicity, 0.03–0.05 kg 1,4-DB eq. to aquatic ecotoxicity, and 0.6–0.76 kg CO2 eq. emissions, mainly attributed to Hg and Al. Evaluation of five reuse scenarios showed that using contaminated sediments in cement and plaster production yields significant environmental benefits, with net negative CO2 impacts (593 to 15,060 kg CO2 eq./t), while road construction presented higher impacts in some categories. Overall, this study provides essential insight into sediment-associated risks in water-scarce regions and proposes environmentally sound reuse options. It offers a replicable framework for mitigating contamination, reducing environmental burdens, and advancing sustainable resource recovery in reservoir sediment management.