Distribution Characteristics And Health Risk Assessment Of Polycyclic Aromatic Hydrocarbons In Cucurbitacae Vegetables

Polycyclic Aromatic Hydrocarbons(PAHs)are a group of typical persistent organic pollutants with carcinogenic,teratogenic and mutagenic effects,which widely distributed in the environment.PAHs can be absorbed by vegetables through various ways,and then migrate,metabolism or accumulate in the vegetable body,thus affecting the normal growth of vegetables,and will be scaled up in the food chain,threatening human health.In this dissertation,Cucumis sativus L.,Momordica charantia L.,Luffa cylindrical L.Roem.and Benincasa hispida var.chieh-qua were used as examples to monitor 16 kinds of PAHs in different part,specified by the U.S.Environmental Protection Agency,analyzed their composition and sources of PAHs,and evaluate the health risks of each cucurbitacae vegetable to people in Nanning,to research the distribution characteristics of PAHs accumulation in vegetables.The aim is to explore the accumulation degree and distribution characteristics of PAHs in vegetables,and provide a theoretical basis for quantitative evaluation of ecological and health risks,on the other hand,it is great significance for the development of corresponding pollution control technology.The mainly results were as follows:1.Comparing the concent levels of ?PAHs in different parts of the same kind of cucurbitacae vegetable,the distribution characteristics as follows,Cucumis sativus L.:leaf>stem>root>peel>petious>flesh>pulp;Momordica charantia L.:leaf>pulp>root>stem>petious>pulp;Benincasa hispida Cogn.var.chieh-quaHow.:leaf>pulp>peel>flesh>root>stem>Petious;Luffa cylindrical L.Roem.:leaf>stem>root>peel>petious>pulp>flesh.2.Comparing the content levels of PAHs in the same parts of different cucurbitacae vegetable,the results showed that the samples of leaf and peel were:Benincasa hispida Cogn.var.chieh-quaHow.>Luffa cylindrical L.Roem>Cucumis sativus L>Momordica charantia L..The content of PAHs in the four kinds of cucurbitacae vegetable roots were no significant differences.3.From the compenent characteristecs of 16 PAHs monomer composition in cucurbitacae vegetable,the content of 5 and 6 ring PAHs was higher,followed by 2 rings,and the detection of 4 and 3 rings was lower.4.The characteristics of polycyclic aromatic hydrocarbons in the leaves of four kinds of melons were analyzed by characteristic ratio method and principal component analysis.The results showed that the polycyclic aromatic hydrocarbons in the leaves were mainly derived from biomass burning,vehicle exhaust emissions and petroleum sources.5.The health risks caused by eating melons in different populations in Nanning were evaluated by USEPA-recommended lifetime cancer risk.The result showed the cancer risk levels of diverse population groups in Nanning by ingesting fruit from cucurbitacae vegetables were in the range of 1.48×10-6 and 7.87×10-5.The cancer risk levels caused by ingesting only edible portions were in the range of 2.23×10-7 and 3.35×10-6.Under the current consumption amount of vegetables,potential carcinogenic risks or no carcinogenic risk exist for Nanning residents by ingesting fruits of cucurbitacae vegetables6.The cucumber leaves were treated with 5 kinds of PAHs mixture,the results showed that the distribution characteristics of PAHs in shed cucumbers was consistent with those of field cucumbers.The PAHs stress treatment showed a low concentration of cucumber growth and a moderate to high concentration inhibition.With PAHs treatment leaves,the SOD and CAT activity reduced,and POD activity and chlorophyll content obvious enhanced.It had negative impacts on fruit soluble sugar and soluble solids.