Distribution Characteristics Of Organochlorine Pesticides In Vegetables From Traditional Planting And Greenhouse Planting

Organochlorine pesticides (OCPs) are a class of persistent organic pollutants and were widely used in our country. OCPs are persisent, highly toxic, and can bioaccumulate in crops and animals. They can enter human body through food chain and are of great concern to human health. Being a great agricultrural producer, greenhouse farming is widely applied in our country because of its heat retaining property and moisturizing effect. Therefore, in order to guarantee the quality of greenhouse vegetables and provide valuable suggestion for human health, it is necessary to learn the difference of OCPs concentration and distribution characteristics in vegetable tissues and its growing environment under traditional planting and greenhouse planting.In this study, we analysed the OCPs concentration and distribution characteristics in tomatoes and cucumbers’tissues and its growing environment under traditional planting and greenhouse planting. The total OCPs in outdoor and greenhouse soils ranged from26.41-46.19ng/g(with a mean of36.97ng/g)and37.39-50.65ng/g(with a mean of44.39ng/g), respectively. The total OCPs in the vegetable tissues were26.89-307.69ng/g(with a mean of102.88ng/g) and33.40-376.72ng/g(with a mean of114.17ng/g) for outdoor and greenhouse, respectively. Total OCPs concentration in the outdoor atmosphere was725.19-910.95pg/m3(with a mean of790.37pg/m3), and1010.90-1225.69pg/m3(with a mean of1084.86pg/m3) for greenhouse atmosphere. It can be seen that the total OCPs concentration in the greenhouse soils, vegetable tissues and atmosphere were all higher than that of outdoor.The rhizosphere OCPs concentrations were higher than that of bulk soil, except for greenhouse HCHs. And the BCFs of greenhouse roots were higher than outdoor. OCPs levels in the soil samples from mature period were higher than that of fruit-hanging period. DDTs were the predominant component in the soil, followed by Endosulfans and HCHs. p, p’-DDE was the main isomer of DDTs. The ratios of DDT/(DDE+DDD) ranged from0.22to0.36, indicating that DDTs in this field came from historical usage.β-Endosulfan concentration was the highest among Ensodulfans, and the source may be the migration and settlement of high level Endosulfans from Tai Lake region. y-HCH was the main component among HCHs isomers. It was found that Lindane was used in this field according to the α-/β-HCH ratios(far less than1). The OCPs levels in the vegetable tissues ranged in the following order:DDTs> HCHs> Endosulfans> Aldrin+Diedrin+Endrin> Chlordanes>Heptachlors. OCPs in the aerial tissues(stem, leaves, fruit) from greenhouse were higher that that from outdoor. The OCPs levels in the stems were always higher campared to roots and leaves. OCPs concentrations in the fruit were the highest among all the tissues. The likely explanation might be the OCPs can translocate among the tissues and accumulated greatly in the growing organs like fruit.OCPs levels in the greenhouse atmosphere were higher than that of outdoor. The OCPs concentrations in the air samples collected from the top, the middle of the vegetable and next to the soil surface in the greenhouse were ranged as follows:soil surface>the middle of the vegetable>the top of the vegetable, while in the outdoor, it ranged in another order:soil surface>the top of the vegetable> the middle of the vegetable. Furthermore, the OCPs concentrations in the air around tomatoes were a little higher than that around cucumbers.