农田土壤中有机磷酸酯和邻苯二甲酸酯的复合污染特征及风险评估

    Combined Pollution Characteristics and Ecological Risk Assessment of Organophosphate Esters and Phthalate Esters in Cropland

    • 摘要: 为调研农田土壤中有机磷酸酯(OPEs)和邻苯二甲酸酯(PAEs)的复合污染情况, 本研究以电缆生产园区附近的农田为样地, 调研了15种OPEs和5种PAEs在土壤水平方向(距园区5~100 m)和垂直方向(深度0~50 cm)的赋存浓度, 通过相关性分析进行污染溯源并探究土壤有机碳对其的影响, 评估OPEs和PAEs复合污染带来的生态风险。结果表明, 土壤中∑15OPEs浓度为77.6~349.4 ng·g-1, ∑5PAEs浓度为691.3~2 405.3 ng·g-1, 其中, ∑15OPEs浓度随着水平距离的增加有所降低, 而∑5PAEs则呈现先升高后降低的现象, 但∑15OPEs和∑5PAEs在土壤中纵向迁移的规律一致, 即浓度随着土层深度的增加呈先降低后升高再降低趋势; 土壤中不同类型OPEs和PAEs在空间分布上存在差异, OPEs浓度排序为氯代OPEs>烷基OPEs>芳基OPEs≈低聚OPEs, PAEs中污染最为严重的是邻苯二甲酸二甲酯(DMP), 其次为邻苯二甲酸二辛酯(DNOP)和邻苯二甲酸二乙酯(DEP); 部分OPEs与PAEs之间存在显著相关性, 污染来源可能受电缆生产产品的影响较大, 同时土壤有机碳影响某些OPEs和PAEs的赋存; 生态风险评估结果表明单一的OPEs或PAEs多为低生态风险(中位值RQ分别为0.02和0.09), 但OPEs和PAEs各自的混合风险熵(MRQ分别为0.58和0.44)可达中等级别, 并且OPEs和PAEs复合污染带来的生态风险(MRQ=1.04)更高。本研究结果表明OPEs和PAEs在电缆园区附近农田土壤中的复合污染需要引起高度关注, 后续需要深入探索OPEs和PAEs的农田健康风险和相关的土壤修复技术。

       

      Abstract: Aiming to investigate the combined pollution of organophosphate esters (OPEs) and phthalate esters (PAEs) in cropland, this study collected soil samples from a cropland near a cable production zone. The soil samples were taken at different distances (5-100 m) to the cable production zone and at each sampling site three soil columns (0-50 cm) were collected. The concentrations of 15 OPEs and 5 PAEs in the soil samples were determined. Through correlation analysis, the pollution sources of OPEs and PAEs were traced and the impacts of soil organic carbon were studied. Additionally, ecological risk assessment on OPEs and PAEs was conducted by using the risk quotient (RQ) method. This study found that the concentrations of ∑15OPEs and ∑5PAEs in soil were 77.6-349.4 and 691.3-2 405.3 ng·g-1, respectively. The concentrations of ∑15OPEs decreased to some extent along with the horizontal distance from the cable production zone, while the levels of ∑5PAEs increased first and then decreased. It might be attributable to the different routes of OPEs and PAEs entering the cropland. In the vertical profile of soil, both the concentrations of ∑15OPEs and ∑5PAEs decreased first, then increased, and finally decreased with the soil depth. Moreover, there existed a spatial difference on the distribution of different kinds of OPEs and PAEs. Among the OPEs, halogenate OPEs (35.9-236.4 ng·g-1) occupied the highest proportion, followed by alkyl OPEs (35.8-154.8 ng·g-1). The levels of aryl OPEs (2.9-15.6 ng·g-1) and oligomeric OPEs (1.2-30.7 ng·g-1) were much lower than those of halogenate OPEs and alkyl OPEs. As for the PAEs, the ones with relatively high concentrations were dimethyl phthalate (DMP, 293.4-1 822.5 ng·g-1), di-n-octyl phthalate (DNOP, 112.8-664.2 ng·g-1), and diethyl phthalate (DEP, 45.3-461.5 ng·g-1). Besides, it is interesting to find that certain OPEs and PAEs were significantly correlated, probably due to their similar sources from the cable factories. In addition, soil organic carbon affected the occurrence of some OPEs and PAEs. According to the results of ecological risk assessment, it indicates that most of the individual OPEs and PAEs (median, RQ=0.02, 0.09) had a low risk, but the combined risk of OPEs or PAEs (MRQ=0.58, 0.44) could reach a medium level and the ecological risk caused by the combined pollution of OPEs and PAEs (MRQ=1.04) was much higher. This study revealed that the combined pollution of OPEs and PAEs in cropland soil should be paid great attention, and further research are required to explore the health risk of OPEs and PAEs in cropland and also the related soil remediation technologies.

       

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