College of Land Science and Technology, China Agricultural University, Beijing 100193, PR China.
College of Land Science and Technology, China Agricultural University, Beijing 100193, PR China; Key Laboratory of Arable Land Conservation (North China), MARA, Beijing 100193, PR China.
Environ Pollut. 2022 Aug 15;307:119501. doi: 10.1016/j.envpol.2022.119501. Epub 2022 May 27.
Field application of manure compost introduces a large quantity of dissolved organic matter (DOM), which can affect the migration of DOM-associated contaminants. In this study, the transport of humic acid (HA) and compost-derived dissolved organic matter (CDOM) in two porous media under various conditions, including ionic types, ionic strength, and influent concentrations, were investigated by column experiments and modeling analysis. Increasing Na concentration did not affect the transport of CDOM and HA in quartz sands, but inhibited CDOM transport in ferrihydrite (Fh)-coated sands. The retention recoveries of CDOM in Fh-coated sands were not changed with increasing NaCl concentration, suggesting that the adsorption of CDOM on Fh-coated sands caused by increasing NaCl concentration was a reversible process. Ca could reduce the mobility of CDOM and HA through bridge bonding and electrostatic interaction. CDOM had a higher mobility than HA in quartz sands under CaCl conditions because the aggregation stability of CDOM was stronger than that of HA. The ferrihydrite coating increased the roughness of sand surface, resulting in lower mobility of CDOM in the Fh-coated sands than in quartz sands. A part of CDOM adsorbed onto Fh-coated sand was strongly bound through ligand exchange-surface complexation. The pore volume of CDOM required to saturate adsorption sites onto the Fh-coated sand depends on the influent CDOM concentration. The influent CDOM with higher concentration required less pore volume to achieve adsorption equilibrium. Modeling analysis suggested that the types of deposition sites provided by Fh-coated sand are mainly irreversible sites. Our findings demonstrated that CDOM transport in the sand columns may change the porous medium's physicochemical properties and alter the hydrochemistry conditions. Therefore, these factors mentioned above should not be ignored when evaluating the environmental risks of CDOM.
粪肥堆肥的田间应用会引入大量的溶解有机物质（DOM），这可能会影响 DOM 相关污染物的迁移。在这项研究中，通过柱实验和模型分析，研究了在不同条件下（包括离子类型、离子强度和进水浓度），腐殖酸（HA）和堆肥衍生溶解有机物质（CDOM）在两种多孔介质中的传输。增加 Na 浓度不会影响 CDOM 和 HA 在石英砂中的传输，但会抑制 CDOM 在铁氢氧化物（Fh）涂覆砂中的传输。随着 NaCl 浓度的增加，CDOM 在 Fh 涂覆砂中的保留回收率没有变化，表明由于 NaCl 浓度的增加导致 CDOM 在 Fh 涂覆砂上的吸附是一个可逆过程。Ca 通过桥键合和静电相互作用可以降低 CDOM 和 HA 的迁移性。在 CaCl 条件下，CDOM 比 HA 在石英砂中具有更高的迁移性，因为 CDOM 的聚集稳定性比 HA 更强。Fh 涂层增加了砂表面的粗糙度，导致 CDOM 在 Fh 涂覆砂中的迁移性低于石英砂。一部分 CDOM 通过配体交换-表面络合被强烈吸附在 Fh 涂覆砂上。Fh 涂覆砂吸附位点达到饱和所需的 CDOM 孔隙体积取决于进水 CDOM 浓度。具有较高浓度的进水 CDOM 达到吸附平衡所需的孔隙体积更少。模型分析表明，Fh 涂覆砂提供的沉积位点类型主要是不可逆位点。我们的研究结果表明，CDOM 在砂柱中的传输可能会改变多孔介质的物理化学性质并改变水化学条件。因此，在评估 CDOM 的环境风险时，不应忽视上述因素。
