Institute of Soil, Water and Environmental Sciences, Volcani Center, ARO, P.O. Box 15159, Rishon LeZion, 7528809, Israel.
Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, 76100, Israel.
Environ Sci Pollut Res Int. 2023 Nov;30(53):113649-113659. doi: 10.1007/s11356-023-30313-1. Epub 2023 Oct 18.
Dissolved organic matter (DOM) from biosolids can alter the sorption of orthophosphate (inorganic phosphorus (IP)) to soils and, therefore, affect the bioavailability of IP. It is not clear how clay mineralogy and solution composition interfere with DOM effects on IP sorption by soils. Hence, we studied the effect of DOM on IP sorption to five semi-arid soils dominated by either illite/smectite (I/S) or kaolinite clays. IP sorption isotherms were constructed in either NaCl or CaCl background solution, with and without the addition of DOM. The IP sorption capacity maxima (S, Langmuir model) of the I/S soils were 33-102% higher in the presence of CaCl, as compared to NaCl. Although DOM had no effect on the IP-S in the presence of CaCl, it increased the IP-S by 35-59% in the presence of the NaCl solution. Surprisingly, DOM sorption to the I/S soils was 30-90% greater in the presence of a Na-dominated solution, as compared to a Ca-dominated solution. In contrast to the I/S soils, the S of the kaolinitic soil was not affected by the background electrolyte (Na, Ca) or the addition of DOM. Furthermore, the addition of IP reduced the sorption of DOM to the kaolinitic soil (by up to 50%) in both background electrolyte solutions. These results highlight the contrasting roles of divalent and monovalent cations in conjunction with DOM in IP sorption to semi-arid I/S soils. We propose a new approach based on two conceptual mechanisms to explain the DOM's enhancement of IP sorption to I/S soils. (1) Under dispersion conditions in the Na-dominated solutions, Ca-mediated DOM-IP complexes bind to the clay's negative planar surfaces. (2) Under flocculation conditions in the Ca-dominated solutions, the distance between adjacent platelets decreases, reducing both the electronegative charge spillover and Ca bridge-mediated DOM sorption. In contrast, the addition of DOM to kaolinite, a multi-platelet clay with a low isomorphic negative charge, reduces IP sorption due to competitive sorption on the clay's broken edges.
生物固体中的溶解有机质 (DOM) 可以改变正磷酸盐（无机磷 (IP)）在土壤中的吸附，从而影响 IP 的生物有效性。目前尚不清楚粘土矿物学和溶液成分如何干扰 DOM 对土壤中 IP 吸附的影响。因此，我们研究了 DOM 对五种以伊利石/蒙脱石 (I/S) 或高岭石粘土为主的半干旱土壤中 IP 吸附的影响。在 NaCl 或 CaCl2 背景溶液中，构建了添加和不添加 DOM 的 IP 吸附等温线。与 NaCl 相比，在 CaCl2 存在下，I/S 土壤的 IP 吸附容量最大值 (S，Langmuir 模型) 高 33-102%。尽管 DOM 对 CaCl2 存在下的 IP-S 没有影响，但它在 NaCl 溶液存在下增加了 35-59%的 IP-S。令人惊讶的是，与 Ca 为主的溶液相比，DOM 对 I/S 土壤的吸附增加了 30-90%。与 I/S 土壤相比，背景电解质 (Na、Ca) 或 DOM 的添加都不会影响高岭土土壤的 S。此外，在两种背景电解质溶液中，添加 IP 都会减少 DOM 对高岭土土壤的吸附（最多减少 50%）。这些结果突出了二价和一价阳离子与 DOM 一起在半干旱 I/S 土壤中对 IP 吸附的作用。我们提出了一种新方法，该方法基于两个概念性机制来解释 DOM 对 I/S 土壤中 IP 吸附的增强作用。(1) 在 Na 为主的溶液中分散条件下，Ca 介导的 DOM-IP 复合物结合到粘土的负平面表面上。(2) 在 Ca 为主的溶液中絮凝条件下，相邻薄片之间的距离减小，从而减少了负电涌和 Ca 桥介导的 DOM 吸附。相比之下，将 DOM 添加到高岭土中，高岭土是一种具有低同晶负电荷的多薄片粘土，由于在粘土的破碎边缘上竞争吸附，会减少 IP 的吸附。
