Anthropogenic Pollution and Ecological Risk in Urban Sediments: Assessing Heavy Metal and Organic Contamination in the Saida Watershed, North-Western Algeria

In this study, an updated analysis of urban pollution in the Saida city watershed, located in North-Western Algeria, is conducted. Our study focused on the presence of heavy metals and organic pollution in urban drainage sediments. The description and quantification of the contaminants detected are presented, and the total levels of trace metals in the sediment samples are compared with standard reference values. The results show that rainfall events and sediment sampling periods have an influence on pollution generation and regeneration processes in the urban catchment. In this research, pollution indices and factors are used to assess the degree of pollution in the study area. Chromium, lead, cadmium, zinc, copper, nickel, and cobalt contents in sediment samples collected after rainfall episodes exceeded toxicity reference limits, indicating significant pollution of the investigated sediments. Cadmium exhibited very high contamination based on the contamination factor and geo-accumulation index values, while lead, copper, and chromium indicated moderate to high contamination. The geo-accumulation index values for zinc and nickel revealed modest contamination, while cobalt and iron contamination in the sediments was non-existent. The contamination levels, on the other hand, suggested that the sediments were heavily polluted. Our findings also indicated the presence of anthropogenic enrichment, since the enrichment factor values are above the threshold value. Furthermore, the results revealed that the sediments possessed a high to severe potential ecological risk rating. A comparison with other basins in Algeria and around the world validated the research site's contamination level.