| 珠江河口地表水锰氧化物对磷的“载-卸”作用 |
| 摘要点击 641 全文点击 272 投稿时间：2023-01-03 修订日期：2023-03-10 |
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| 中文关键词 咸-淡水交互区 盐度梯度 磷 赋存形态 迁移转化 |
| 英文关键词 freshwater-saltwater interaction zone salinity gradient phosphorus speciation migration and transformation |
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| 中文摘要 |
| 地表径流输送的磷在河口水环境营养结构平衡和初级生产力调节中起到了关键作用.通过测定不同季节珠江下游及河口地表水阴阳离子、总磷及其形态、颗粒态铁（PFe）、颗粒态锰（PMn）和颗粒态铝（PAl）等理化性质,探究咸-淡水交互区内磷的时空分布特征,并识别控制磷迁移转化的关键因素.结果表明,ρ（TP）（28.88~233.68 μg·L-1）受到沉降和稀释作用随盐度升高呈下降趋势,且占比大小为：溶解态无机磷（DIP,37.3%）>颗粒态无机磷（PIP,22.7%）>溶解态有机磷（DOP,21.0%）>颗粒态有机磷（POP,19.0%）.PIP与PFe、PMn和PAl有显著（P<0.05）的共迁移相关关系,水体盐度的升高促进了悬浮颗粒态无机磷的解吸,且该过程主要发生在咸-淡水界面附近.无机磷的固-液分配系数（Kd）与盐度间的显著正相关关系（P<0.001）表明,高盐度水域PIP主要以更稳定的结合形态存在.Kd与PMn的显著正相关关系（P<0.01）证明了Mn氧化物对磷的“载-卸”作用：从淡水环境中吸附携载无机磷,迁移至高盐度水体释放. |
| 英文摘要 |
| Phosphorus (P) conveyed by surface runoff plays an essential role in regulating nutrient balance and primary production in estuarine waters. In this study, basic physiochemical properties, total phosphorus (TP, including speciation), particulate iron (PFe), particulate manganese (PMn), and particulate aluminum (PAl) of the surface water in the Pearl River Estuary (PRE) in different seasons were determined to investigate the spatiotemporal distribution characteristics of P and to identify the crucial factor controlling P migration and transformation in the freshwater-saltwater interaction zone. TP concentrations (28.88-233.68 μg·L-1) decreased with increasing salinity gradient owing to deposition and dilution. The proportions of P speciation followed a decreasing order as dissolved inorganic phosphorus (DIP, 37.3%) > particulate inorganic phosphorus (PIP, 22.7%) > dissolved organic phosphorus (DOP, 21.0%) > particulate organic phosphorus (POP, 19.0%). PIP was positively related to PFe, PMn, and PAl (P < 0.05), confirming their concurrent migration behaviors. In addition, the increase in salinity promoted the desorption of phosphate on the suspended particulate matters, which mainly took place near the freshwater-saltwater interface. A significant positive correlation (P < 0.001) between the solid-liquid phase partitioning coefficient (Kd) of phosphate and salinity indicated that PIP was present mainly in more stable forms in the brackish water. Most importantly, a better relationship between Kd and PMn (P < 0.01) supported our scientific hypothesis of the "load-unload" effect of Mn oxides on P:particulate-carrying phosphates transported from the freshwater zone tend to be desorbed and released into the brackish water. |
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