哒嗪硫磷水解与土壤降解研究

Hydrolysis of pyridaphenthione and its degradation in soils

采用室内模拟方法,研究了哒嗪硫磷在东北黑土、江西红壤和南京黄棕壤3种不同类型土壤中的降解特性及pH、温度和表面活性剂(SDS)浓度对水解的影响。结果表明,哒嗪硫磷水解速率随pH值与温度的升高而显著加快,在15℃、pH 5缓冲溶液中水解半衰期为216.56 d,在35℃、pH 9缓冲溶液中半衰期为3.47 d,平均温度效应系数为2.98。SDS能显著抑制哒嗪硫磷水解,且随着浓度的增大抑制作用增强。哒嗪硫磷在3种土壤中的降解速率依次为南京黄棕壤>东北黑土>江西红壤,半衰期分别为10.27、78.75、105.00 d,降解速率随土壤pH值的增大而增大。灭菌处理下,哒嗪硫磷在3种土壤中半衰期显著延长,其中在南京黄棕壤中半衰期延长近10倍,哒嗪硫磷在土壤中降解主要为微生物降解。

The degradation of pyridaphenthione in three different types of soils,black soil of Northeast China,red soil of Jiangxi and yellow-brown soil of Nanjing were investigated,and the effects of temperature,pH and concentrations of surfactant（SDS） on hydrolysis of pyridaphenthione in aqueous solutions were also studied in the laboratory.The results showed that the hydrolytic rate of pyridaphenthione obviously increased with the increasing temperature and pH value.The half life of pyridaphenthione was 216.56 days in pH 7 solution at 15 ℃,while 3.47 days in pH 9 solution at 35 ℃.The average temperature coefficient was 2.98.We also found that SDS could restrain the hydrolysis rates of pyridaphenthione and the restraining degree was enhanced with the increasing concentration of SDS.The degradation rates of pyridaphenthione in three kinds of soils showed the following sequence： yellow-brown soil of Nanjing black soil of northeast red soil of Jiangxi,and the half life was 10.27,78.75 and 105.00 days,respectively.The degradation rate was positively correlated with the pH values of soils.The half life of pyridaphenthione significantly extended under sterilization treatment.Among them,the half life increased by nearly 10 times in the yellow-brown soil of Nanjing,which indicated that pyridaphenthione was degraded mainly by biodegradation in soils.