Pollution Characteristics And Health Risk Assessment Of Polycyclic Aromatic Hydrocarbons And Phthalic Acid Esters In The Tobacco-soil System

In view of polycyclic aromatic hydrocarbons(PAHs) and phthalic acid esters(PAEs) widely distributed and serious harm to people in environment medium. Collecting the tobacco leaves and soils in the central of Guizhou province as a research object, the pollution characteristics, the source identification and the health risk assessment of PAHs and PAEs has been discussed in this study through determination the content of PAHs and PAEs in soils and tobacco leaves. The main findings showed as follows.(1) A method for determination of PAHs in soil and tobacco by gas chromatography-mass spectrometry(GC-MS) based on the soxhlet extraction and four-channel chromatographic separation purification was established. And the method for determination of PAEs by GC-MS with the ultrasonic extraction, the purification of four-channel chromatographic separation for soil samples and silica gel column chromatography for tobacco samples was developed. The recoveries are more than 80% and this method can determine the PAHs and PAEs in samples efficiency.(2) The results showed that the concentration of total 16 PAHs ranged from 72.94 ?g/kg to 941.77 ?g/kg with the average of 390.54 ?g/kg, it was in low pollution level, and the content of 2 ~ 3 rings of PAHs accounted by 66.64% in total PAHs. However, the PAHs content in tobacco was 130.02 ~ 1545.35 ?g/kg with the average of 779.37 ?g/kg and the 4 ~ 5 rings PAHs accounted high part. In tobacco samples, Ba P accounted by 54.86% with the average concentration of 422.64 ?g/kg. Principal component analysis(PCA) and ratio method analysis indicated the major source of PAHs in tobacco-soil system were the combustion of coal, straw and wood, also oil and oil combustion.(3) The contents of PAEs in soil and tobacco were decided by DBP and DEHP contents. PAEs concentration in soil ranged from 0.84 mg/kg to 25.68 mg/kg with the average of 5.4 mg/kg, and it was much higher than that in tobacco(0.74 ~ 4.79 mg/kg, average: 1.75 mg/kg). The concentration of DEHP in soil(4.64 mg/kg) was 4.4 times higher than that in tobacco(1.06 mg/kg). The tobacco planted area has been threatened by PAEs, DEP and DMP was 6.6 and 1 ~ 10 times more than the U.S. control standards, respectively. DBP exceed 2.2 ~ 27.7 times of the standard and accounted by 87.5% and DEHP accounted by 85.45%. Principal component analysis showed the major source of PAEs in tobacco-soil were the application of agricultural plastic films, fertilizers, pesticides and sewage irrigation in tobacco planted process.(4) The results found that PAHs and PAEs on farmers had a low level of non-cancer risk to farmers, but the carcinogenic risk was higher. The carcinogenic hazard index(CHI) was N.D ~ 3.24 × 10-4 and it was the low level risk above. Ba P and DBA had the big contribution of carcinogenicity with 37.5% and 16.7% of the sampling points in a moderate level of risk, respectively. The CHI of BBP was the low level risk varied from N.D to 1.17 × 10-5. However, the DEHP has high CHI with 1.82 × 10-4 ~ 1.08 × 10-2, 60.4% of the sampling points were in a moderate level of risk and 9.6% of the sampling points were in a high level of risk. PAHs and PAEs have high potential carcinogenic risk to farmers.