State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences , Beijing 100012, China.
State Environmental Protection Key Laboratory for Lake Pollution Control, Research Center of Lake Eco-environment, Chinese Research Academy of Environmental Sciences , Beijing 100012, China.
Environ Sci Technol. 2016 Mar 15;50(6):2938-45. doi: 10.1021/acs.est.5b05450. Epub 2016 Feb 23.
Knowledge of the interfacial interactions between aspartate and minerals, especially its competition with phosphate, is critical to understanding the fate and transport of amino acids in the environment. Adsorption reactions play important roles in the mobility, bioavailability, and degradation of aspartate and phosphate. Attenuated total reflectance Fourier-transform infrared (ATR-FTIR) measurements and density functional theory (DFT) calculations were used to investigate the interfacial structures and their relative contributions in single-adsorbate and competition systems. Our results suggest three dominant mechanisms for aspartate: bidentate inner-sphere coordination involving both α- and γ-COO(-), outer-sphere complexation via electrostatic attraction and H-bonding between aspartate NH2 and goethite surface hydroxyls. The interfacial aspartate is mainly governed by pH and is less sensitive to changes of ionic strength and aspartate concentration. The phosphate competition significantly reduces the adsorption capacity of aspartate on goethite. Whereas phosphate adsorption is less affected by the presence of aspartate, including the relative contributions of diprotonated monodentate, monoprotonated bidentate, and nonprotonated bidentate structures. The adsorption process facilitates the removal of bioavailable aspartate and phosphate from the soil solution as well as from the sediment pore water and the overlying water.
了解天冬氨酸与矿物质之间的界面相互作用，特别是其与磷酸盐的竞争，对于理解环境中天冬氨酸的归宿和传输至关重要。吸附反应在天冬氨酸和磷酸盐的迁移性、生物有效性和降解中起着重要作用。利用衰减全反射傅里叶变换红外（ATR-FTIR）测量和密度泛函理论（DFT）计算研究了单吸附剂和竞争体系中的界面结构及其相对贡献。我们的结果表明，天冬氨酸有三种主要的吸附机制：涉及α-和γ-COO(-)的双齿内配位、通过静电吸引和天冬氨酸 NH2 与针铁矿表面羟基之间的氢键形成的外配位络合物。界面天冬氨酸主要受 pH 控制，对离子强度和天冬氨酸浓度变化的敏感性较低。磷酸盐的竞争显著降低了天冬氨酸在针铁矿上的吸附容量。而磷酸盐的吸附受天冬氨酸的存在影响较小，包括二质子化单齿、一质子化双齿和非质子化双齿结构的相对贡献。吸附过程有利于将生物有效性的天冬氨酸和磷酸盐从土壤溶液以及沉积物孔隙水和上覆水中去除。
