ABSTRACT
Rivers in mining areas were influenced by contaminants such as nitrogen, phosphorus and organic matter due to domestic and agricultural wastewater discharge in addition to pollutants caused by mining activities. In this study, surface sediment samples of rivers in Tongling city were collected to address the effect of season and pollution type on the abundance of nitrifiers and denitrifiers using quantitative polymerase chain reaction (QPCR) technique targeting at the ammonia monooxygenase (amoA) and nitrite reductase (nir) genes. The results showed that the average ahundance of ammonia oxidizing archaea (AGA) (ranging from 1.74 x 105 to 1.45 x 108 copies · g⻹) was 4.39 times that of ammonia oxidizing hacteria (AGH) (ranging from 1.39 x 105 to 3.39 x 107 copies · g⻹); and the average abundance of nirK gene (ranging from 4.45 x 106 to 1.51 x 108 copies · g) was almost a thirtieth part of nirS gene (ranging from 1.69 x 107 to 8.55 x 109 copies · g⻹). The abundance of AOA was higher in spring and autumn, and lower in summer and winter. And sediment AOB abundance was higher in spring and winter than in summer and autumn. Meanwhile, the abundance of nir genes was in the order of spring (nirS )/autumn (nirK) > summer > winter > autumn (nirS )/spring (nirK). Moreover, the abundance of bacterial and archaeal arnoA and nirS genes in sediments influenced by mine pollution was generally higher than that in sediments influenced by agricultural non-point pollution, whereas the abundance of nirK gene showed an opposite trend.
