农药在蔬菜中的残留动态及降解规律

为了寻找有效降低蔬菜中农药残留的方法，促进蔬菜产业的健康发展，本研究选用百菌清、氰戊菊酯、乐果3种使用广泛、具有代表性的农药为试验材料，采用气相色谱法测定蔬菜上农药的残留动态。结果表明：施药当天氰戊菊酯、乐果、百菌清3种农药在生菜中的残留量要明显高于番茄，分别高出42.9%、44.9%、57.8%，第7天3种农药在番茄和生菜的残留量分别为154~285μg/kg、258~528μg/kg。施药当天乐果、百菌清、氰戊菊酯3种农药在大棚中芹菜上的残留量较露地分别高出2.9%、7.1%、6.0%。在5~20天期间露地芹菜的农药降解速度也明显高于大棚。氰戊菊酯的沉降试验表明：1天内沉降量为农药用量的8.77%~19.64%。农药在蔬菜上的起始浓度与蔬菜食用部分表面积比有关；大棚蔬菜的农药降解速度要明显慢于露地蔬菜农药的降解速度；农药的沉降现象是影响大棚农药残留量的重要因素。

Study on the Degradation of Pesticides Residues in a Closed Environment

The aims were to seek for the method of reduce pesticide residues of vegetables in greenhouse, and promote the healthy development of vegetable industry. Chlorothalonil, fenvalerate and dimethoate was selected as the test material. The degradation characteristics of pesticide residues were studied. The results showed that in the first day, fenvalerate, dimethoate, chlorothalonil residues in lettuce were higher than that of tomato respectively 42.9%, 44.9%, 57.8%. In seventh day, tomato and lettuce pesticide residues were 154-285μg/kg, 258-528μg/kg. The first day, dimethoate, chlorothalonil, fenvalerate residues in celery of greenhouse was higher than that of field respectively 2.9%, 7.1%, 6%. During 5-20 days, the pesticide degradation rate of field was also higher than that in greenhouse. The initial concentration related with edible part surface area ratio of vegetable. Pesticide degradation rate of greenhouse vegetables was obviously slower than the field vegetables. Subsidence phenomenon of pesticides was an important factor in the impact of pesticide residues.