Ongoing sea level rise will have a major impact on mobility and migration of contaminants by changing a number of natural phenomena that alter geochemistry and hydrology of subsurface environment. In-situ immobilization techniques may be a promising remediation strategy for mitigating contaminant mobility induced by sea level rise. This study investigated the reaction mechanisms of magnesium oxide (MgO) with aqueous Pb and As under freshwater and seawater using XAFS spectroscopy. Initial concentrations of Pb and As in freshwater strongly controlled the characteristics of the reaction product of MgO. Our study revealed that i) the removal of aqueous Pb and As by MgO was increased by the elevation of seawater concentration, and ii) the removal of As was attributed primarily to (inner-sphere) surface adsorption on MgO, independent on seawater concentrations, and iii) the retention mechanism of Pb was dependent on seawater concentrations where formations of Pb oxides and adsorption on the MgO surface were predominant in solutions with low and high salinity, respectively. The release of As fixed with MgO significantly increased in seawater compared to freshwater, although the amount of As desorbed accounted for <0.2% of total As.

持续的海平面上升将通过改变改变地下环境地球化学和水文学的许多自然现象，对污染物的迁移和迁移产生重大影响。原位固定技术可能是缓解海平面上升引起的污染物迁移的有前途的补救策略。本研究利用XAFS光谱技术研究了氧化镁（MgO）与Pb和As水溶液在淡水和海水中的反应机理。淡水中Pb和As的初始浓度强烈地控制了MgO反应产物的特性。我们的研究表明，i）MgO对Pb和As的去除随着海水浓度的升高而增加，并且ii）As的去除主要归因于MgO在（内层）表面的吸附，iii）铅的保留机理取决于海水浓度，在低盐度和高盐度溶液中，铅氧化物的形成和在MgO表面的吸附分别占主导地位。与MgO固定的As的释放量与淡水相比在海水中显着增加，尽管解吸的As量占总As的<0.2％。