Study On Effects Of DEP And DOP On The Enzyme Activities, Respiration And Microbial Biomass Carbon Of Soil

With the rapid development of industry and agriculture, plastic products have been produced and applied extensively. The pollution of phthalates on soil environment has become an increasingly serious problem. At present, study on effects of phthalates on soil environment has been seldom reported. Effects of different concentrations (10, 50, 100, 500, 1000mg/kg) of DEP and DOP on four kinds of soil enzyme activities (phosphatase, invertase, urease and catalase), soil respiration and microbial biomass carbon have been researched under laboratory condition in this article. A preliminary analysis of its mechanism has been made so as to provide a theoretical basis for the evaluation of its ecotoxicological effects of phthalates.The result indicated that:1. Application of DEP can chiefly stimulate catalase activity; The catalase activity was also stimulated by DOP, and the trend followed the regulation of"activation-fluctuation -stability"during the course of cultivation. However, compared with other indicators, influence of PAEs on catalase were not obvious.2. DEP has the following effects on invertase: soil invertase treated with concentration of 50,500,1000mg/kg DEP changed as"inhibition - activation - inhibition",however,10,100 mg/kg DEP inhibited the invertase activity during the whole course of cultivation; DOP chiefly inhibited soil invertase activity, in addition to 500mg/kg treatment at the sampling points on 3 days after cultivation and 1000mg/kg treatment at the sampling points on 3, 10 days after cultivation stimulated soil invertase, all the other treatments inhibited the activity of invertase.3.1000mg/kgDEP stimulated the activity of phosphatase, however, other concentrations affected the phosphatase as the regulation of"stimulus-inhibition-stability"; With the increasing of the concentration of DOP, the extent of inhibition had reduced, until it has stimulated the activity of phosphatase.4. In addition to 10mg/kg DEP treatment at the sampling points on 10 days after cultivation and 100mg/kg DEP treatment at the sampling points on 30 days after cultivation had slightly stimulated the activity of ureas, all the other concentrations of DEP treatment inhibited the activity of ureas; 10mg/kg DOP stimulated the activity of urease, however, other concentrations of DOP inhibited the activity of urease during the course of cultivation. 5. DEP had some fluctuation effects on soil respiration during the whole course of cultivation, and at the end of cultivation, 10, 50,100mg/kg DEP treatments have the same trend with the contrast, however, 500,1000mg/kg DEP treatments have a slight upward trend; DOP also had some fluctuation effects on soil respiration. After the 42 days of cultivation, 10, 500mg/kg treatments have the same trend with the contrast, and 50,100,1000mg/kg treatments still have a slight upward trend.6. With the extension of time, both DEP and DOP affected the microbial biomass carbon as the regulation of fluctuated at first and maintained stability eventually. But all the DEP treatments reduced the microbial biomass carbon obviously despite of the stability, and the extent of reduction increased with the increasing of concentration; the microbial biomass carbon under DOP treatment resumed to the level of the contrast after 42 days of cultivation.Compared completely the effects of DEP and DOP on the six indicators, invertase was suggested to be the biotoxical index of DEP and DOP pollution in soils.