Influence Of Irrigation With Treated Papermaking Wastewater On Wetland Soil Microbes And Enzyme Activities

The change processes, of reed wetland soil enzyme activities and soil microbial community structures, responsed to the stresses of treated papermaking wastewater were studied in our works. And then one artificial wetland was builded to test the wetland soil physical and chemical properties, organic chloride content and enzyme activity under stress by leaching wastewater. The PCR-DGGE technologies were used to analyse the influence of irrigation with papermaking bleaching wastewater on wetland soil microbes and enzyme activities.An extensive reed field survey was employed to assess the impacts of long-term irrigation with treated papermaking wastewater, as compared to river water irrigated fields, on soil physicochemical properties, soil enzyme activities, and soil microbial community metabolic profiles. The results revealed that long-term irrigation with the wastewater resulted in a slight increase of p H value, Na+ and electrical conductivity, while a remarkable increase was identified regarding to soil organic carbon, total nitrogen and total phosphorous. Irrigation caused a remarkable increase in soil electrical conductivity and resulted in soil salinization. Furthermore, soil enzymes displayed significantly increased activities(except for catalase) in the irrigated fields, while the microbial ability of utilizing carbon source was enhanced.A artificial wetland was builded to test the wetland soil physical and chemical properties, organic chloride content and enzyme activity under stress by leaching wastewater. The experimental results show that bleaching wastewater irrigation resulted in the increase of soil nutrient content and soil salinization. Organic chloride in bleaching wastewater result in the accumulation and the increase of AOX and TX in soil. In irrigated field, the activities of soil cellulose enzyme, polyphenol oxidase and invertase were significantly increased and urease activity was slight inhibited, and phosphatase activity was obvious inhibited.The diversities of microbial communities were analysed by soil bacterial 16 S and fungi 18 S r DNA sequences, by molecular manipulations, e.g., microbial total DNA extraction, PCR and DGGE electrophoresis. The experimental results showed that soil bacterial community structures had obvious evolution processes. Soil bacterial communities under the stress of papermaking wastewater were very different from the control. Bleaching wastewater significantly inhibited bacterial activity and reduced soil bacterial diversities. The main bands in bacterial DGGE profiles represented Lysinibacillus fusiformis, Paenisporosarcina quisquiliarum, Erythrobacter flavus and some uncultured bacterium. The wastewater irrigation caused decreasing in the number of soil fungi and their metabolic activities at the nitia l stage. With irrigation prolonged, the wastewater provides rich nutrients, so irrigation activated soil fungi activity and improved fungal diversities. The main bands in fungal DGGE profiles represented Scopulariopsis brevicaulis, Amyloporia xantha and some uncultured fungus.