Beijing Key Laboratory for Source Control Technology of Water Pollution, Beijing Forestry University, Beijing, 100083, China.
Water Research Center, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW, 2052, Australia; CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei, 230026, China.
Environ Res. 2022 Sep;212(Pt D):113567. doi: 10.1016/j.envres.2022.113567. Epub 2022 May 26.
The use of vivianite (Fe(PO)∙8HO) as a slow-release P fertilizer in agriculture could be a promising way for the utilization of the recovered vivianite products from sewage treatment systems but the efficiency of vivianite-P release in the rhizospheric soil was yet unclear. In this work the dissolution of vivianite was investigated under anoxic and aerobic conditions with the focus on the effects of citrate as a common organic matter in the rhizosphere by tracking the kinetics of P release and the variations of aqueous and solid phases. The results show that citrate effectively induced the dissolution of vivianite particles at pH 6 with simultaneous release of Fe and PO-P. The enhancement of vivianite dissolution was positively correlated to the concentrations of citrate with complete dissolution observed when citrate was above 6 mM. Compared with anoxic conditions, aerobic conditions further enhanced the dissolution of vivianite to some extent, which could be partially attributed to the oxidation and removal of aqueous Fe in the solution that drove the equilibrium towards dissolution. In the presence of 2 mM citrate, the decrease in pH from 6.0 to 4.0 enhanced the vivianite-P release by 56.1%, indicating the pH dependence of the citrate-induced vivianite dissolution. This study has shown that the efficiency of P release from vivianite products as a fertilizer varies largely under different physico-chemical conditions in the rhizospheric microenvironment, which is critical for determining the dosage of vivianite for a specific soil.
将蓝铁矿（Fe(PO)∙8HO）用作农业中的缓释 P 肥料，可能是利用污水处理系统中回收的蓝铁矿产品的一种有前途的方法，但蓝铁矿-P 在根际土壤中的释放效率尚不清楚。在这项工作中，研究了在缺氧和有氧条件下蓝铁矿的溶解情况，重点是研究柠檬酸作为根际中常见有机物的影响，通过跟踪 P 释放动力学和水相和固相的变化来研究。结果表明，柠檬酸在 pH 值为 6 时有效地诱导了蓝铁矿颗粒的溶解，同时释放出 Fe 和 PO-P。蓝铁矿溶解的增强与柠檬酸的浓度呈正相关，当柠檬酸浓度高于 6 mM 时，观察到蓝铁矿完全溶解。与缺氧条件相比，有氧条件在一定程度上进一步促进了蓝铁矿的溶解，这部分归因于溶液中 Fe 的氧化和去除，使平衡向溶解方向移动。在 2 mM 柠檬酸存在下，pH 值从 6.0 降低到 4.0 使蓝铁矿-P 的释放增加了 56.1%，这表明了柠檬酸诱导蓝铁矿溶解的 pH 值依赖性。这项研究表明，作为肥料的蓝铁矿产品在根际微环境中不同物理化学条件下的 P 释放效率差异很大，这对于确定特定土壤中蓝铁矿的用量至关重要。
