Institute of Coastal Environmental Pollution Control, Key Laboratory of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao, 266100, China; College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, China.
Institute of Coastal Environmental Pollution Control, Key Laboratory of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao, 266100, China; College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, China.
Aquat Toxicol. 2019 Jan;206:81-90. doi: 10.1016/j.aquatox.2018.11.010. Epub 2018 Nov 12.
Phthalate esters (PAEs), one class of the most frequently detected endocrine-disrupting chemicals (EDCs) in marine environment, have aroused wide public concerns because of their carcinogenicity, teratogenicity, and mutagenicity. However, the environmental fate of PAEs in the occurrence of harmful algal blooms remains unclear. In this research, four PAEs with different alkyl chains, i.e., dimethyl phthalate (DMP), diethyl phthalate (DEP), diallyl phthalate (DAP), and dipropyl phtalate (DPrP) were selected as models to investigate toxicity, uptake, and degradation of PAEs in seawater grown with K. brevis, one of the common harmful red tide species. The 96-h median effective concentration (96h-EC) values followed the order of DMP (over 0.257 mmol L) > DEP (0.178 mmol L) > DAP (0.136 mmol L) > DPrP (0.095 mmol L), and the bio-concentration factors (BCFs) were positively correlated to the alkyl chain length. These results indicate that the toxicity of PAEs and their accumulation in K. brevis increased with increasing alkyl chains, due to the higher lipophicity of the longer chain PAEs. With growth of K. brevis for 96 h, the content of DMP, DEP, DAP, and DPrP decreased by 93.3%, 68.2%, 57.4% and 46.7%, respectively, mainly attributed to their biodegradation by K. brevis, accounting for 87.1%, 61%, 46%, 40% of their initial contents, respectively. It was noticed that abiotic degradation had little contribution to the total reduction of PAEs in the algal cultivation systems. Moreover, five metabolites were detected in the K. brevis when exposed to DEP including dimethyl phthalate (DMP), monoethyl phthalate (MEP), mono-methyl phthalate (MMP), phthalic acid (PA), and protocatechuic acid (PrA). While when exposed with to DPrP, one additional intermediate compound diethyl phthalate (DEP) was detected in the cells of K. brevis in addition to the five metabolites mentioned above. These results confirm that the main biodegradation pathways of DEP and DPrP by K. brevis included de-esterification, demethylation or transesterification. These findings will provide valuable evidences for predicting the environmental fate and assessing potential risk of PAEs in the occurrence of harmful algal blooms in marine environment.
邻苯二甲酸酯（PAEs）是海洋环境中最常检测到的内分泌干扰化学物质（EDCs）之一，由于其致癌性、致畸性和致突变性，引起了广泛的公众关注。然而，PAEs 在有害藻华发生过程中的环境归宿仍不清楚。在这项研究中，选择了具有不同烷基链的四种 PAEs，即邻苯二甲酸二甲酯（DMP）、邻苯二甲酸二乙酯（DEP）、邻苯二甲酸二烯丙酯（DAP）和邻苯二甲酸二丙酯（DPrP），作为模型，以研究其在赤潮常见种之一的短凯伦藻（K. brevis）生长的海水中的毒性、摄取和降解。96 小时半数有效浓度（96h-EC）值的顺序为 DMP（> 0.257mmol L）>DEP（0.178mmol L）>DAP（0.136mmol L）>DPrP（0.095mmol L），生物浓缩因子（BCFs）与烷基链长度呈正相关。这些结果表明，由于较长链 PAEs 的疏脂性更高，PAEs 的毒性及其在 K. brevis 中的积累随烷基链的增加而增加。随着 K. brevis 生长 96 小时，DMP、DEP、DAP 和 DPrP 的含量分别下降了 93.3%、68.2%、57.4%和 46.7%，主要归因于 K. brevis 的生物降解，分别占其初始含量的 87.1%、61%、46%和 40%。值得注意的是，非生物降解对藻类培养系统中 PAEs 总量的减少贡献很小。此外，当暴露于 DEP 时，在 K. brevis 中检测到五种代谢物，包括邻苯二甲酸二甲酯（DMP）、邻苯二甲酸单乙酯（MEP）、邻苯二甲酸单甲酯（MMP）、邻苯二甲酸（PA）和原儿茶酸（PrA）。而当暴露于 DPrP 时，除了上述五种代谢物外，在 K. brevis 的细胞中还检测到一种额外的中间化合物邻苯二甲酸二乙酯（DEP）。这些结果证实了 K. brevis 对 DEP 和 DPrP 的主要生物降解途径包括去酯化、去甲基化或转酯化。这些发现将为预测 PAEs 在海洋环境中有害藻华发生过程中的环境归宿和评估其潜在风险提供有价值的证据。
