三种化肥对除草剂氯磺隆降解的影响

The effects of three kinds of fertilizers on degradation of chlorsulfuron

通过砂培实验探讨了Ca(H2PO4)2、NH4HCO3、(NH2)2CO对氯磺隆降解的影响.实验中用直接气相色谱检测氯磺隆.结果表明:Ca(H2PO4)2的加入使砂样呈酸性,促进氯磺隆的降解,降解曲线遵从抛物线方程;而NH4HCO3的加入使砂样呈碱性,阻碍氯磺隆的降解,降解曲线同样遵从抛物线方程.砂样添加尿素后,氯磺隆高浓度组中氯磺隆的降解曲线遵从抛物线方程,半衰期为30.5天;氯磺隆低浓度组中氯磺隆降解曲线先迅速下降,然后上升,在20天左右出现一顶峰,最后缓慢下降.理论分析认为,这是因为氯磺隆与尿素先形成结合态形式,使可测定氯磺隆浓度迅速下降,然后在微生物等原因的作用下又逐渐破坏其结合,使氯磺隆又释放出来;高浓度组形成的结合态浓度相对较低,不足以显现下凹趋势,只表现出降解曲线平缓.尿素与氯磺隆形成结合态,可能对后茬作物造成危害,应引起高度重视.

<Abstrcat> We investigated the effects of Ca(H_2PO_4)_2, NH_4HCO_3 and (NH_2)_2CO on degradation of chlorsulfuron in sand culture. Chlorsulfuron was directly measured by using gas chromatography with an electron capture detector. Because Ca(H_2PO_4)_2 decreases the pH of the sample solution, it facilitates the degradation. The rate of the degradation is subject to a parabolic equation. On the contrary, NH_4HCO_3 hinders the degradation because it makes the pH of the sample solution increase. The curve of the degradation also conforms to a parabolic equation. However, the curve of the degradation, when (NH_2)_2CO is used, is quite different from those of the former two cases. It descends sharply at first, then ascends and forms a peak around the 20th day, then it slowly descends. It indicates that the concentration of chlorsulfron quickly decreases at the beginning, then increases after 10 days. Twenty days later, the curve follows a pseudo-first order equation. It shows that chlorsulfuron combines with (NH_2)_2CO to form some kinds of compounds at first, then the compounds decompose into some other kinds of substances. The combining process progresses quickly. However, the decomposing process, fulfilled by microbes, goes slowly.