The Promoting Effect and Mechanism of Nitrogen Conversion in the Sediments of Polluted Lake on the Degradation of Organic Pollutants

At present, the research on the nitrification kinetics and the degradation of organic pollutants by co-metabolism are mostly based on the pure culture system of microorganisms in laboratory, and few are derived from environmental samples in the field. The study took the sediments of No.1 Pond of Yanjia Lake as the research object. Through field drilling and sampling, different points are selected for nitrification experiments with adding ammonium. The results showed that the nitrification obvious occurred in the topsoil and the sediments at the depth of 50-100 cm of well 1. At the same time, the content of hexachlorobenzene in the organic pollutants decreased the most, by 36.6% and 49.4% respectively. It can be considered to screen nitrification and hexachlorobenzene co-metabolism microorganisms from these two sediments. No obvious nitrification process was detected in the sediments at the depth of 250-300 cm of well 1 and 150-200 cm of well 2, but there were processes such as ammonium adsorption and being used as nitrogen source to decrease ammonium concentration. The contents of r-HCH, heptachlor-epoxide and endrin Ketone at the depth of 250-300 cm of well 1 decreased by 48.8%, 90.2% and 63.3%, respectively, and those at the depth of 150-200 cm of well 2 decreased by 55.8%, 87.4% and 32.1%, respectively. It shows that adding ammonium to these sediments can promote the degradation of organic pollutants.