Abstract
This work was devoted to investigating the long-term cumulative effect of municipal sewage treatment plant (STP) effluents on the sediments, near the plant outlet, in Yunliang River in Nanjing, China. Laboratory experiments were performed to assess the effect of different aeration modes on the migration and distribution of phosphorus (P) in the sediments. The field investigation showed that the concentrations of organic matter, different P fractions, dehydrogenase activity and alkaline phosphatase activity in sediments near the STP outlet were higher than those in the upstream site. The results of laboratory studies documented that the retention of P in sediments mainly depended on the characteristics of sediments. Collectively, long-term intermittent aeration accelerated the conversion of parts of organic phosphorus to occluded Fe–P due to that Fe2+ were oxidized to Fe3+ gradually, inactivating the sediments P, which preventing P release completely even in the case of anoxic conditions. Compared with aerating to water, aerating to sediments was more effective on transferring total phosphorus and dissolved inorganic phosphorus (DIP) in overlying water to sediments. Additionally, microbial enzymes activity was directly related to the concentrations of DIP, indicating that enzymes activity could serve as sensitive indicators of nutrient dynamics in water ecosystems.
Published Version
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