Evaluating the Ecological Impact of Wastewater Discharges on Microbial and Contaminant Dynamics in Rivers

Abstract

This study focused on assessing the impact of pollutants discharged from the Fuxin Meng Wastewater Treatment Plant (FMWWTP) on the microbial communities in the Xi River; specific comparison between upstream and downstream regions was made. Water samples were obtained by mixing morning, midday, and evening sampling at two points: one upstream and one downstream, each 500 m from the FMWWTP outfall. Utilizing metagenomic sequencing in conjunction with measured conventional physical and chemical properties, the research aimed to elucidate differences in microbial community structure, metabolic functions, potential biological contamination, and antibiotic resistance gene prevalence. The findings indicated a notable decrease in microbial diversity downstream compared to upstream; this was influenced primarily by the effluent from FMWWTP. This disparity in microbial diversity was evident at various taxonomic levels, with downstream samples showing higher diversity at the phylum level than at the genus level. Furthermore, downstream microbial populations demonstrated a broader range of metabolic and functional genetic diversity. Interestingly, the abundance of metabolic systems was generally greater downstream, with the notable exception of energy metabolism. This could be attributed to the stress imposed on downstream microorganisms by organic chemicals discharged from the treatment plant, and this prompts an enhanced metabolic decomposition function. The study also uncovered significant levels of potential biological contamination and antibiotic resistance gene pollution. This was more pronounced downstream of FMWWTP. In conclusion, discharge from FMWWTP has a substantial impact on the microbial communities of the Xi River, and this underscores the urgent need to optimize wastewater treatment processes to better comply with environmental quality standards.