Effects Of Sewage And Cd Combined Pollution On Soil And Plant System

Sewage irrigation has great worth in northern arid areas. Although it relieves the critical situation of water resources, it also brings agricultural pollution in irrigated area, among which heavy metal pollution problems are the severest. The accumulation of heavy metals will inevitably destroy natural soil microflora and soil enzyme activities, and lower soil quality. Survey and evaluate of soil enzyme activities assists in the identification of soil heavy metals pollution. Therefore soil enzyme is one of concerned topics at home and abroad.The survey results indicated that Taiyuan pollutied area has a long history and a large area, and cadmium pollution is serious. To investigate the effects of long-term sewage irrigation on the soil-plant systems, we studied the relative relationship between soil enzyme activities and heavy metals content in the sewage irrigation area, and the effect of sewage and Cd combined pollution on seed germination rate of maize,antioxidant enzyme system in maize and spinach.40 representative soil samples were selected according to the survey results of heavy metals content. Colorimetric and volumetric were used to measure urease, invertase, polyphenol oxidase and catalase activities. Colorimetric and volumetric were also used to analysis the relative relationship between soil enzymes activities and heavy metals content. The results showed that urease activity and Mn,As content were positively correlated; invertase activity and Cu, Cd content were positively correlated; catalase activity and Cu, As, Ni and Mn content were positively correlated; and polyphenol oxidase activity and Zn, Cd, Cu and Pb content was negatively correlated.Laboratory incubation methods, with different concentrations of sewage treatment series (0,25%,50%,75%,100%) and with different concentrations of Cd2+ and sewage treatment series (0,10,25,50,75,100 mg·L-1), were tested on maize seed processing, testing seed germination rate of maize. The results showed that the serum treatment inhibited the seed germination rate, and with the water concentration increases, the inhibition effect enhanced; different concentrations of Cd2+treatment on seed germination rate were that the inhibition effect was promoted at low concentration and was inhibitied at high concentration.Based on the previous trials, continue to test on the maize seed. Colorimetric and titration were used to measure maize seedlings polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL),β-1,3 glucanase (β-1,3 glucanase) and catalase (CAT) activity. The results showed that in both different concentrations of sewage and sewage and cadmium combined pollution treatment series, PPO, PAL and CAT activities were promoted in the low concentration and were inhibitied at high concentration, whileβ-1,3 glucanase activities had no significant change in different concentrations of sewage treatment series.Using greenhouse method, prepared with different concentrations (0,1,5,10,50 mg-L-1) Cd2+ solution with water and sewage, test on the spinach processing. The testing contents and methods as the previous ones. The results showed that the various of antioxidant enzyme activities of spinach is different in all treatment series. With the increasing concentration of Cd2+, PPO and PAL activities increased firstly and then decreased; while CAT activity was slightly higher in alone treatment, activity decreased in combined treatment;β-1,3 glucanase activity decreased with increasing concentration; with the same Cd2+ concentration, sewage and Cd combined treatments inhibited the PPO, PAL and CAT activities, while promotingβ-1,3 glucanase activity.