Miao Shenyu, DeLaune R D, Jugsujinda A
School of Life Sciences, Guangzhou University, Guangzhou 510006, China.
Sci Total Environ. 2006 Dec 1;371(1-3):334-43. doi: 10.1016/j.scitotenv.2006.07.027. Epub 2006 Aug 24.
The influence of sediment redox conditions on solubility of selected metals and nutrients in sediment from a coastal Louisiana freshwater lake (Lake Cataouatche) receiving diverted Mississippi River water was quantified. Sediment redox was cycled step wise in 50 mV increments between oxidized (-200 to +500 mV) and reduced (+500 to -200 mV) conditions. Changes in sediment oxidation/reduction status and pH influenced solubility of both metals and nutrients. When redox potential (Eh) was increased from -200 to +500 mV, sediment pH decreased from 7.1 to 5.7. When the sediment Eh decreased from +500 to -200 mV, pH increased from 5.7 to 7.1. The increase in sediment acidity upon oxidation resulted in the release of the Pb, Ca, Mg, Al, and Zn into solution. The solution concentration of these elements was inversely proportional to Eh (P</=0.05). The concentration of Fe, Mn, and P in sediment suspension was strongly governed by changes in oxidation-reduction status of sediment. The oxidation of reduced sediment resulted in a decrease in amount of Fe and Mn in solution, a result of the conversion of soluble ferrous and manganous form to less soluble ferric and manganic form. Following reduction of oxidized sediment, Fe and Mn became more soluble because the ferric iron and manganic manganese form changed to ferrous and manganous form. Phosphorus behavior as influenced by oxidation/reduction status was closely related to Fe and Mn chemistry with an increase in phosphate following iron reduction. This study demonstrated that sediment redox potential is an important parameter affecting metal and nutrient solubility and mobility in Louisiana coastal freshwater lake sediment. Reduction or aeration status of sediment should be considered in predicting the release of these elements into the aquatic environment.
对路易斯安那州沿海一个接收密西西比河分流河水的淡水湖（卡塔奥atche湖）沉积物中选定金属和养分的溶解度受沉积物氧化还原条件的影响进行了量化。沉积物氧化还原在氧化（-200至+500 mV）和还原（+500至-200 mV）条件之间以50 mV的增量逐步循环。沉积物氧化/还原状态和pH值的变化影响了金属和养分的溶解度。当氧化还原电位（Eh）从-200 mV增加到+500 mV时，沉积物pH值从7.1降至5.7。当沉积物Eh从+500 mV降至-200 mV时，pH值从5.7升至7.1。氧化时沉积物酸度的增加导致铅、钙、镁、铝和锌释放到溶液中。这些元素的溶液浓度与Eh成反比（P≤0.05）。沉积物悬浮液中铁、锰和磷的浓度受沉积物氧化还原状态变化的强烈控制。还原沉积物的氧化导致溶液中铁和锰的量减少，这是由于可溶性亚铁和亚锰形式转化为溶解度较小的铁和锰形式。氧化沉积物还原后，铁和锰变得更易溶解，因为三价铁和三价锰形式转变为亚铁和亚锰形式。受氧化/还原状态影响的磷行为与铁和锰的化学性质密切相关，铁还原后磷酸盐增加。这项研究表明，沉积物氧化还原电位是影响路易斯安那州沿海淡水湖沉积物中金属和养分溶解度及迁移率的重要参数。在预测这些元素向水生环境的释放时，应考虑沉积物的还原或曝气状态。
