速灭威在枸杞土壤中的迁移及淋溶行为模拟研究

Simulation study of migiration and leaching of metolcarb in several soils in Lycium barbarum field

应用薄层层析法和柱淋洗法研究了速灭威在3种枸杞产区土壤——灌淤土、灰钙土和潮土中的迁移及淋溶特性,并探讨了土壤类型、pH值、淋溶量等因素对其淋溶的影响。结果表明:速灭威在三种枸杞产区土壤中的移动性由大到小依次为:灰钙土>潮土>灌淤土,比移值Rf分别为0.47、0.37和0.35,移动速率m/(cm·h^–1/2)分别为3.52、2.58和2.35。速灭威在三种土壤中的比移值Rf在0.35—0.64之间,属于中等移动农药。速灭威在三种土壤中的淋出率由大到小依次为:潮土>灰钙土>灌淤土,淋出率分别为63.1%、50.0%和28.3%。随着水量的增加,速灭威在三种土壤中的淋溶率也越来越大。当淋溶水量大于350 mL时,除潮土外,灌淤土和灰钙土中几乎无速灭威流出,进一步证明了速灭威可能在潮土中的吸附力较低,而在灌淤土和灰钙土中的吸附力较高。淋溶液pH值不同,淋溶率也有较大差异,在灌淤土和灰钙土中弱酸性条件利于速灭威淋出,在潮土中性条件易于淋出,这可能与土壤的pH及全盐量含量不同有关,在弱酸性条件下,潮土的全盐量含量高,增大了对速灭威的吸附力,导致速灭威的淋溶率降低。速灭威在土壤中属于中等移动农药,对地下水存在一定的危险。

TLC and soil column method were established for determing the characteristics of migiration and leaching of metolcard in several soils,and the most critical influences such as soil type,pH and amount of water were used to discuss the impact of leaching rate.The results indicated that the mobility of metolcard in different soils were as follows:sierozem>fluvo-aquic soil>irrigation silting soil with Rf 0.47,0.37 and 0.35,and the movement speeds were 3.52,2.58 and 2.35,individually.The Rf of metolcarb in several soils were in the scope of 0.35-0.64,therefore,metolcarb belonged to middle mobile pesticide.Meanwhile,the leaching rates of metolcarb in several soils were as follows:fluvo-aquic soil>sierozem>irrigation silting soil with the leaching rates were 63.1%,50.0%and 28.3%respectively.The leaching rate of metolcarb in the three soils were increased with the increasing amount of water applied.When the amount of water was more than 350 mL,there were hardly any metolcarb from the sierozem soil and irrigation silting soil column except fluvo-aquic soil.It was proved that metolcarb was adsorbed firmly in sierozem soil and irrigation silting soil.In the meantime,pH was anthor important fator to leaching rate;pH was low,which significantly increased metolcarb in sierozem soil and irrigation silting soil.It was possibly because different soils had different pH and total saline.For fluvo-aquic soil,it had high total saline;the adsorb capacity was enhanced in the weak acid condtion;as a result,the leaching rate of metolcarb from fluvo-aquic soil column was reduced.Metolcarb belonged to middle mobile pesticide,and could harm to groundwater.