Metal/metalloid and phosphorus characteristics in porewater associated with manganese geochemistry: A case study in the Jiulong River Estuary, China.
Metal/metalloid and phosphorus characteristics in porewater associated with manganese geochemistry: A case study in the Jiulong River Estuary, China.
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DOI：
10.1016/j.envpol.2019.113134
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发表时间：
2019-12
影响因子：
8.9
通讯作者：
Feng Pan;Huatai Liu;Zhanrong Guo;Yu Cai;Y. Fu;Jinye Wu;Bo Wang;Aiguo Gao
中科院分区：
文献类型：
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作者：
Feng Pan;Huatai Liu;Zhanrong Guo;Yu Cai;Y. Fu;Jinye Wu;Bo Wang;Aiguo Gao
沉积物孔隙水是上覆水中污染物的重要来源，但其对金属和磷的再活化机制尚待研究。本研究采用高分辨率透析（HR-Peeper）和薄膜扩散梯度（DGT）采样器，测定了中国九龙江口沿岸沉积物中孔隙水溶解的铁（Fe）、锰（Mn）、钴（Co）、铬（Cr）、钒（V）、硒（Se）、砷（As）、P和DGT-Labile S。结果表明，上覆水体中溶解态Mn、Se和P含量较高，表明存在Mn、Se和P过量的潜在水体污染。孔隙水中溶解态Mn含量高于溶解态Fe含量，尤其是在淹没点，表明Mn（III/IV）还原是有机碳（OC）降解的主要成岩途径。其通过竞争性抑制Fe（III）还原和Fe（II）再氧化直接影响Fe循环。溶解态Co、Cr、V、Se、As和P与Mn呈显著正相关，与Fe无相关性，表明这些金属和P的迁移与Mn循环有关，而与Fe循环无关。此外，金属（loid）s，P和Mn的浓度在淹没网站的共同升高归因于加强锰还原加上缺氧燃料的OC降解。Mn、Se和P的正向扩散通量与上覆水中Mn、Se和P的过量浓度以及其他金属（loid）的近似正向扩散通量相一致，表明沉积物Mn（III/IV）的还原和伴随的金属（loid）和P的再活化可能是金属（loid）和P向上覆水迁移的重要途径。
Sediment porewater can be an important source of contaminants in the overlying water, but the mechanisms of metal(loid) and phosphorus (P) remobilization remain to be investigated. In this study, high-resolution dialysis (HR-Peeper) and diffusive gradients in thin films (DGT) samplers were used to determine the porewater dissolved iron (Fe), manganese (Mn), cobalt (Co), chromium (Cr), vanadium (V), selenium (Se), arsenic (As), P and DGT-Labile S in coastal sediments in the Jiulong River Estuary (JRE), China. The results showed that high concentrations of dissolved Mn, Se and P were present in the overlying water, indicating potential water pollution with excessive amounts of Mn, Se and P. The dissolved Mn concentrations in the porewater were higher than the dissolved Fe concentrations, especially at submerged sites, demonstrating that Mn(III/IV) reduction is the dominant diagenetic pathway for organic carbon (OC) degradation, which directly affects Fe cycling by the competitive inhibition of Fe(III) reduction and Fe(II) reoxidation. Dissolved Co, Cr, V, Se, As and P show significant positive correlations with Mn but nearly no correlations with Fe, suggesting that the mobility of these metal(loid)s and P is associated with Mn but not Fe cycling in this region. In addition, the coelevated concentrations of the metal(loid)s, P and Mn at the submerged sites are attributed to the strengthened Mn reduction coupled with OC degradation fueled by hypoxia. The higher positive diffusion fluxes of Mn, Se and P were consistent with the excess Mn, Se and P concentrations in the overlying water, together with the approximately positive fluxes of the other metal(loid)s, indicating that sediment Mn(III/IV) reduction and concomitant metal(loid) and P remobilization might be vital pathways for metal(loid) and P migration to the overlying water.