Xu Gang, Li Fasheng, Wang Qunhui
Department of Soil Pollution Control, Chinese Research Academy of Environmental Sciences, Beijing, PR China.
Sci Total Environ. 2008 Apr 15;393(2-3):333-40. doi: 10.1016/j.scitotenv.2008.01.001. Epub 2008 Feb 7.
In this study, we analyze the pollution and degradation characteristics of two kinds of phthalate esters (PEs), dibutyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP), in two kinds of soils collected from non-cultivated, crop, greenhouse, and vegetable fields from the Harbin and Handan Districts, China. The results demonstrate that DBP has relatively high residual levels in the soils, ranging from 3.18 to 29.37 mg/kg in fluvo-aquic soils of the Handan District (average 14.06 mg/kg) and 2.75-14.62 mg/kg in black soils of the Harbin District (average 7.60 mg/kg). Residual levels of DEHP reach 1.15-7.99 mg/kg in fluvo-aquic soils of the Handan District (average 4.86 mg/kg) and 0.44-4.20 mg/kg in black soils of the Harbin District (average 2.35 mg/kg). All non-cultivated soils contain the lowest contents of PEs, suggesting that the kinds of pollutants are largely derived from human agricultural activities. Laboratory experiments verify that the degradations of two kinds of PEs are mainly via microbial processes. The microbial populations are higher and reduce more slowly in black soils than those in fluvo-aquic soils. These observations might partially explain the lower levels of residuals and higher degradation rates of PEs pollutants in black soils than those in fluvo-aquic soils. The detection of DBP metabolites indicates that DBP biodegradation might begin by ester hydrolysis to form monobutyl phthalate (MBP) and corresponding alcohol. The MBP then degrades to phthalic acid or butyl benzoate, which might be possibly caused by microbial decarboxylation. The two derivatives of MBP degrade to form protocatechuate through ring cleavage.
在本研究中，我们分析了从中国哈尔滨和邯郸地区的非耕地、农田、温室和菜地采集的两种土壤中两种邻苯二甲酸酯（PEs），即邻苯二甲酸二丁酯（DBP）和邻苯二甲酸二（2-乙基己基）酯（DEHP）的污染和降解特征。结果表明，DBP在土壤中的残留水平相对较高，在邯郸地区的潮土中为3.18至29.37mg/kg（平均14.06mg/kg），在哈尔滨地区的黑土中为2.75至14.62mg/kg（平均7.60mg/kg）。DEHP在邯郸地区潮土中的残留水平为1.15至7.99mg/kg（平均4.86mg/kg），在哈尔滨地区黑土中的残留水平为0.44至4.20mg/kg（平均2.35mg/kg）。所有非耕地土壤中PEs的含量最低，这表明这些污染物主要源自人类农业活动。实验室实验证实，两种PEs的降解主要通过微生物过程进行。黑土中的微生物种群数量比潮土中的更高，且减少速度更慢。这些观察结果可能部分解释了黑土中PEs污染物的残留水平低于潮土且降解率高于潮土的原因。DBP代谢产物的检测表明，DBP的生物降解可能首先通过酯水解形成邻苯二甲酸单丁酯（MBP）和相应的醇。然后，MBP降解为邻苯二甲酸或丁基苯甲酸，这可能是由微生物脱羧作用引起的。MBP的两种衍生物通过开环降解形成原儿茶酸。
