Features Of Organic Pollutants In Vegetable Fields Of Dongguan And Their Concentration Control For Vegetable

Features of Organic Pollutants in Vegetable Fields of Dongguan and Their Concentration Control for VegetableZhang Maosheng(Department of Environmental Engineering, Ji Nan University, Guangzhou, 510632)Vegetables have been polluted by all kinds of toxic chemicals because vegetable fields are usually located in suburban or urban-rural interface which are affected by waste substance from cities and agricultural chemicals used widely. However, up to now few Semivolatile Organic Compounds such as polycyclic aromatic hydrocarbons(PAHs)which have harmful impact on human health have been included in control standards of pollutants in "pollution-free agricultural products".Ecology of organic pollution in agricultural system has become the hot issue and forward research field.In this study, seven kinds of organic pollutants including 44 compounds in various vegetable specie, soil and irrigation water samples from vegetable fields of Dongguan were systematically determined by Gas chromatography-mass spectrum(GC-MS), then taken cabbage and mustard as target vegetable,phthalic acid esters(PAEs) as objective compounds, pot experiments in glasshouse were conducted to study the ecological characteristics of organic pollution and remediation in vegetable system. The main results as follows:1. Seven kinds of organic pollutants were detected in different examined vegetables, soils or irrigation water from eight vegetable fields. The total contents of six PAEs comounds(∑PAEs)were the highest in the seven kinds of compounds, ranging from 0.412-7.979mg/kg for vegetables, 0.242~1.710mg/kg for soils and 0.29-2.73μg/L for irrigation water, respectively, followed by PAHs and nitrobenzenes, The total contents of sixteen PAHs comounds(∑PAHs) ranged from 0.176-3.261mg/kg for vegetables, 0.048-1.797mg/kg for soil, 0.19-1.72μg/L for irrigation water while those of chlorobenzenes(CBs), ethers, halogenated hydrocarbons, amines were lower. The compounds number detected was most in vegetable samples, and irrigation water was the least. In the same kind of compounds, one or several compounds predominated in most of samples.2. The distribution patterns of Semivolatile Organic Pollutants in vegetables were different which were related to vegetable species, different position and sampling field. In the PAHs compounds, Naphthalene,Phenanthrene,Anthracene,Fluoranthene and Pyrene predominated in most samples; In the PAEs compounds, DnBP and DEHP predominated. Some vegetables had been polluted by the same kinds of toxic chemical in various degree,for exmaple PAHs.and PAEs.3. Soils were detected 29 kind of compounds.In the soil samples, the highest total contents of∑PAHs,∑PAEs,∑CBs, were in the Chashan field; the highest total contents of∑NBs and ethers were in the Yiwu field;the highest total contents of halogenated hydrocarbons were in the Tangxia field; the highest total contents of amines were in the Shijie field DnBP and DEHP predominated in the soil. One or several compounds predominated in most of soil samples Contents of some organic pollutants in soils in this study were higher to some degree than those reported in other countries, and some of them exceeded the USA Control Standard of Soil.The contents of all kinds of compounds in Shanmei field were lower.4. Irrigation water were detected 10 kind of compounds As for irrigation water,the highest total contents PAEs and PAHs were in the Dongcheng field. Compared USA standard of underwater quality, all compounds below to Standard Value(50μg/L) 5. Cabbage and mustard were grown in pot with poddy soil under glasshouse conditions with 5 kinds of PAEs added.In the conditon of PAEI,The presence of manure,fowl dung,organic fertilizer and interplanting of another crop in vegetablel could significantly decreased6. In the conditon of PAEII,The presence of surfactant(Tween-80),fowl dung, in vegetablel could significantly decreased,but the presence of manure, organic fertilizer in vegetablel could significantly increased.