Combined Effects Of MTBE And Pb On Physical Indexes In Brassica Campestris And Soil Enzyme Activity

Methyl tertiary-butyl ether is a kind of gasoline additive which widely used in the early 1980 s, it can reduced the CO in automobile exhaust. It wills enther into the environment because of using and leaking in store. As one kind of heavy metal, Pb is widespread and cannot be degraded in soil. The main harmful effects of Pb on planrs are about physiological and biochemical effects and DNA damage. And the physiological and biochemical effects show that Pb blocked the process of photosynthesis and accelerated the oxidative damage. Combined pollution has become a hot research area, so there is a practical significance in the effect of physical indexes in rape seeding and soil enzyme activity under MTBE and Pb. Main research results are as follows:(1) Under the effect of low concentration of Pb, MTBE in low concentrations can increase the activity of SOD, POD, CAT, chlorophyll content and decrease MDA and praline content. With the concentration of MTBE increase, the activity of SOD, POD, CAT and chlorophyll content decrease and that MDA and praline content increase. When the concentration of MTBE was 0.5mg/L, it could increase the content of chorophyl-b, carotenoid and soluble protein. The treatment of 5 mg/L MTBE could increase POD activity and chorophyl-a. The concentration of 50 mg/L MTBE significantly increased the activity of SOD. Under the treatment of 100 mg/L MTBE activated CAT. Soluble protein and praline content were markedly increased after MTBE treatment of concentration of 50 mg/L, whereas SOD activity was significantly inhibited.(2) Under the effect of high concentration of Pb, the effect of the same concentration of MTBE showed more obvious effects on rapeseed indicator. The concentration of 5mg/L MTBE increased the content of chorophyl-a and the concentration of 5mg/L MTBE increased the content of chorophyl-b. When the concentration of MTBE was lower than 0.05 mg/L, carotinoid content was decreased. However, the MDA, praline and soluble protein content was increased and that POD activity was decreased when the concentration MTBE was higher than 200 mg/L.(3) Under the signal effect of MTBE, with the concentration of MTBE increasing, the activity of soil urease showed the increased trend and that the activity of soil saccharase was decreased at first and then increased. Combined effects between MTBE and Pb on soil catalase showed decrease and then increase and that soil catalase was increased after higher concentration of MTBE and Pb. When the concentration of MTBE was higher than 20 mg/L, the activity of urease and catalase in soil markedly increased. Soil sucrase was significantly inhibited after exposed to MTBE.(4) Combined effect between MTBE and Pb, with the concentration of MTBE increasing, soil urease activity increased at first and then decreased and increased. The combined effect on soil saccharase showed decrease and increase trend. Soil catalase activity decreased and then increased. When the concentration of MTBE was higher than 20mg/L, combined effect on soil urease displayed facilitation effect. When the concentration of MTBE was lower than 20mg/L, combined effect on soil catalase showed reducing effect. Combined effect markedly inhibited the activity of soil sucrase.。(5)The content of Pb in plants and soil markedly increased exposed to combined pollution than signal effect of MTBE. With the concentration of MTBE increasing, the content of heavy metal in rape increased after exposed to combined effect, which suggested that MTBE increased mobility of Pb and that Pb content in soil was decreased.