| 泉州山美水库及入库河流沉积物中多溴二苯醚的时空分异和降解分析 |
| 摘要点击 1446 全文点击 721 投稿时间：2020-03-09 修订日期：2020-04-13 |
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| 中文关键词 多溴二苯醚 沉积物 时空分异 降解 山美水库 入库河流 水源水库 |
| 英文关键词 polybrominated diphenyl ethers (PBDEs) sediment spatiotemporal differentiation degradation Shanmei Reservoir inflowing river water-source reservoir |
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| 中文摘要 |
| 为了解城市水源水库中多溴二苯醚（PBDEs）的时空分异和同系物的降解来源及其贡献，分析了泉州山美水库及入库河流表层沉积物中PBDEs的含量、污染程度、空间分布、水文期变化、赋存量、同系物组成及其降解来源的贡献.结果表明，入库河流沉积物中∑PBDEs中值（1072.1 ng ·g-1）是山美水库（160.4 ng ·g-1）的6.7倍，山美水库单位面积沉积物中∑PBDEs的赋存量（80.3 kg ·km-2）是太湖的6.3倍，北美五大湖的188倍，其污染程度较国内外大多数湖库更严重，且以BDE-209为主（84.5%~99.2%）.水库大多数样点（r为0.564~0.994，P<0.034）及河流各点（r为0.953~1.0，P<0.000）间PBDEs组成相似度较高，入库区和入库河流样点间极显著正相关（r为0.779~0.964，P<0.005）且相关性强于其他功能区，显示入库河流是水库中PBDEs的主污染源.库尾区与入库河流相关性较低（r为0.454~0.915，P≤0.128），受九都镇影响较大.各样点∑PBDEs水文期变化较一致（r为0.617~0.714，P≤0.077），但水文期变化对∑PBDEs的影响统计不显著（P=0.178，Two-Way ANOVA），而点位变化则对∑PBDEs有极显著影响（P=0.0001），入库区和其他功能区有（近）显著差异（P为0.019~0.061），表明PBDEs在水库沉积物中的空间分布变异大于水文期变化.PBDEs自然降解从河流到入库区再到库中区逐渐增加，且各级还原脱溴速率不同，部分BDE因其继续降解速率较慢而累积.丰度比值法研究表明，低溴BDE主要源自十溴二苯醚的逐级还原脱溴自然降解.Deca-BDE降解产生的Nona-BDE约70%以上可较快降解生成Octa-BDE，BDE-208约85%源自BDE-209的降解，从Octa-BDE到Penta-BDE的降解过程中，部分Octa-BDE和Hexa-BDE同系物因降解较慢而累积，Penta-BDE到Tri-BDE降解率在70%以上. |
| 英文摘要 |
| To investigate the spatiotemporal differentiation of polybrominated diphenyl ethers (PBDEs) in urban water-source reservoirs and degradation sources of BDE homologues and their contributions, we analyzed the contents, pollution degrees, spatial distributions, hydrological period changes, inventories, profiles, and degradation source contributions of PBDEs in the surface sediments of Shanmei Reservoir and its inflowing river, Quanzhou, China. The results showed that the median ∑PBDEs (1072.1 ng ·g-1) in the inflowing river sediment was 6.7 times than that of the reservoir (160.4 ng ·g-1) and the total amount of ∑PBDEs in sediments per unit area (80.3 kg ·km-2) was 6.3 times than that of Taihu Lake and 188 times than that of the Great Lakes in North America. The pollution degrees of PBDEs in Shanmei Reservoir were more severe than those of most lakes and reservoirs at home and abroad, which was dominated by BDE-209 (84.5%-99.2%). Most of the sampling sites in the reservoir (r 0.564-0.994, P<0.034) and the inflowing river (r 0.953-1.0, P<0.000) had high similarity in the composition of PBDEs. Significantly positive correlations (r 0.779-0.964, P<0.005) were observed between the reservoir entry area and river sampling sites, which were stronger than the other functional areas, indicating that the inflowing river was a major pollution source of PBDEs in the Shanmei Reservoir. The tail region of the reservoir had low correlations with the inflowing river (r 0.454-0.915, P≤0.128), and was relatively much more affected by Jiudu Town. The changes in hydrological period of the ∑PBDEs were relatively consistent at each sampling site (r 0.617-0.714, P≤0.077), but the impact of the changes in the hydrological period on the ∑PBDEs was not statistically significant (P=0.178, Two-Way ANOVA). However, the site changes had a significant influence on the ∑PBDEs (P=0.0001), and significant or nearly differences were observed between the reservoir entry area and other functional areas (P 0.019-0.061), indicating that the spatial distribution variations of the PBDEs in reservoir sediments were greater than the changes in hydrological period. The natural degradation of the PBDEs gradually increased from the river to the reservoir entry area and then to the central reservoir area. The reductive debromination rates varied at different brominated levels, and some BDE homologues accumulated due to their slowly continued degradation velocities. Research on abundance ratios indicated that the lower brominated BDE homologues were mainly derived from the natural degradation of decabromodiphenyl ether by stepwise reductive debromination. Approximately 70% of Nona-BDE produced by Deca-BDE degradation could rapidly be degraded to form Octa-BDE. Approximately 85% of BDE-208 was derived from the degradation of BDE-209. During the degradation process from Octa-BDE to Penta-BDE, some Octa-BDE and Hexa-BDE homologues accumulated due to relatively slower degradation velocities, and the degradation rates of Penta-BDE to Tri-BDE were above 70%. |
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