Indirect influence of eutrophication on air - water exchange fluxes, sinking fluxes, and occurrence of polycyclic aromatic hydrocarbons
Indirect influence of eutrophication on air - water exchange fluxes, sinking fluxes, and occurrence of polycyclic aromatic hydrocarbons
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富营养化对气水交换通量、下沉通量和多环芳烃发生的间接影响
DOI：
10.1016/j.watres.2017.06.026
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发表时间：
2017
期刊：
影响因子：
12.8
通讯作者：
Yao Shuchun
中科院分区：
文献类型：
--
作者：
Tao Yuqiang;Yu Jing;Lei Guoliang;Xue Bin;Zhang Fengju;Yao Shuchun
水体富营养化如何影响疏水性有机污染物（HOCs）的生态地球化学过程是一个亟待解决的问题。虽然富营养化对沃茨中HOCs的生态地球化学过程的直接影响已经得到了很好的解决，但富营养化对HOCs的生态地球化学过程的间接影响在很大程度上仍然未知。本文以我国大型浅水富营养化太湖和多环芳烃（PAHs）为例，就富营养化对大气-水交换通量、沉降通量和HOCs发生的间接影响提供了新的认识。不同地点的多环芳烃气-水交换通量在不同季节有很大差异.春、夏、冬三季的沉降通量分别为14 855.3 ± 1579.9、3548.9 ± 650.6和5588.4 ± 530.7 ng m−2d− 1。表层沉积物中的相应浓度分别为713.1 ± 78.6、339.7 ± 36.6和293.0 ± 35.2 ng g−1d.w。研究结果首次表明，春季蓝藻从表层沉积物中向水体的补充降低了表层沉积物中PAHs的浓度，但增加了水体中PAHs的浓度;冬季蓝藻的越冬增加了表层沉积物中PAHs的浓度。富营养化间接导致的高pH值降低了PAHs的季节性气水交换通量（增加净挥发），降低了表层沉积物的芳香性和浮游植物细胞表面的疏水性，从而减少了PAHs在表层沉积物和浮游植物中的积累。沉降通量和每日损失的多环芳烃从水柱浮游植物生物量下降，因为从水柱下沉的有机物的分数与浮游植物生物量下降。我们的研究为HOCs的生物泵提供了新的补充知识，对于了解亚热带浅水富营养化沃茨水体中富营养化与HOCs生物地球化学过程之间的耦合具有重要意义。
How eutrophication affects biogeochemical processes of hydrophobic organic contaminants (HOCs) in aquatic environments is a pending challenge. Although the direct influence of eutrophication on biogeochemical processes of HOCs in waters has been well addressed, the indirect influence of eutrophication on biogeochemical processes of HOCs remains largely unknown. Here we take the large shallow eutrophic Lake Taihu in China and polycyclic aromatic hydrocarbons (PAHs) as examples to provide novel knowledge on the indirect influence of eutrophication on air – water exchange fluxes, sinking fluxes, and occurrence of HOCs. The air – water exchange fluxes of individual PAHs varied dramatically at different sites in all studied seasons. The sinking flux of ΣPAH16was 14 855.3 ± 1579.9, 3548.9 ± 650.6, and 5588.4 ± 530.7 ng m−2d−1in spring, summer, and winter. The corresponding concentration of ΣPAH16in surface sediments was 713.1 ± 78.6, 339.7 ± 36.6, and 293.0 ± 35.2 ng g−1d.w. Our study for the first time suggested that recruitment of cyanobacteria from surface sediments to water column in spring reduced the concentrations of PAHs in surface sediments, but enhanced their concentrations in the bulk water column, and overwintering of cyanobacteria in winter enhanced the concentrations of PAHs in surface sediments. High pH induced indirectly by eutrophication decreased seasonal air – water exchange fluxes (enhanced net volatilization) of PAHs, reduced the aromaticity of surface sediments and the hydrophobicity of phytoplankton cell surface, and reduced the accumulation of PAHs in surface sediments and phytoplankton consequently. Sinking fluxes and daily loss of PAHs from the water column decreased with phytoplankton biomass because the fraction of organic matter sinking from the water column decreased with phytoplankton biomass. Our study provides novel complementary knowledge for the biological pump for HOCs, and has important implications for understanding the coupling between eutrophication and biogeochemical processes of HOCs in subtropical shallow eutrophic waters.