School of Water Conservancy and Civil Engineering, Northeast Agricultural University, Harbin, 150030, China; Northeast Agricultural University/Heilongjiang Academy of Environmental Sciences Joint Postdoctoral Mobile Station, 150030, China.
School of Water Conservancy and Civil Engineering, Northeast Agricultural University, Harbin, 150030, China.
Chemosphere. 2023 Jul;329:138555. doi: 10.1016/j.chemosphere.2023.138555. Epub 2023 Apr 3.
Phenanthrene (Phe), a typical polycyclic aromatic hydrocarbon (PAH) pollutant, poses an enormous safety risk to rice-crab coculture (RC) paddy ecosystems. In this study, humic acid-modified purified attapulgite (HA-ATP) with a composite structure was successfully fabricated to adsorb PAHs released from paddy soil to overlying water in RC paddy ecosystems in Northeast China. The maximum crab bioturbation intensities for dissolved Phe and particulate Phe were 64.83nullng/L·(cm·d) and 214.29nullng/L·(cm·d), respectively. The highest concentration of dissolved Phe released from paddy soil to overlying water due to crab bioturbation reached 80.89nullng/L, while the corresponding concentration of particulate Phe reached 267.36nullng/L. The dissolved organic carbon (DOC) and total suspended solid (TSS) concentrations in overlying water increased correspondingly and were strongly correlated with dissolved Phe and particulate Phe concentrations, respectively (P < 0.05). When 6% HA-ATP was added to the surface layer of paddy soil, the efficiency of the adsorption of Phe release was 24.00%-36.38% for particulate Phe and 89.99%-91.91% for dissolved Phe. Because HA-ATP has a large adsorption pore size (11.33 nm) and surface area (82.41nullm/g) as well as many HA functional groups, it provided multiple hydrophobic adsorption sites for dissolved Phe, which was conducive to competitive adsorption with DOC in the overlying water. In contrast to that adsorbed by DOC, the average proportion of dissolved Phe adsorbed by HA-ATP reached 90.55%, which reduced the dissolved Phe concentration in the overlying water. Furthermore, even though the particulate Phe was resuspended by crab bioturbation, HA-ATP immobilized particulate Phe due to its capacity to inhibit desorption, which achieved the goal of reducing the Phe concentration in the overlying water. This result was confirmed by research on the adsorption-desorption characteristics of HA-ATP. This research provides an environmentally friendly in situ remediation method for reducing agricultural environmental risks and improving rice crop quality.
菲（Phe）是一种典型的多环芳烃（PAH）污染物，对中国东北稻蟹共作（RC）稻田生态系统构成巨大安全风险。本研究成功制备了具有复合结构的腐殖酸修饰纯化凹凸棒石（HA-ATP），以吸附 RC 稻田生态系统中稻田土壤释放到上覆水中的 PAHs。溶解态 Phe 和颗粒态 Phe 的最大蟹生物扰动强度分别为 64.83ng/L·(cm·d)和 214.29ng/L·(cm·d)。由于蟹生物扰动，稻田土壤释放到上覆水中的最大溶解态 Phe 浓度达到 80.89ng/L，相应的颗粒态 Phe 浓度达到 267.36ng/L。上覆水中溶解有机碳（DOC）和总悬浮固体（TSS）浓度相应增加，与溶解态 Phe 和颗粒态 Phe 浓度分别呈强相关性（P<0.05）。当 6%HA-ATP 添加到稻田表土层时，对颗粒态 Phe 释放的吸附效率为 24.00%-36.38%，对溶解态 Phe 的吸附效率为 89.99%-91.91%。由于 HA-ATP 具有较大的吸附孔径（11.33nm）和比表面积（82.41nm2/g）以及丰富的 HA 官能团，为溶解态 Phe 提供了多个疏水性吸附位点，有利于与上覆水中的 DOC 进行竞争吸附。与被 DOC 吸附的 Phe 相比，HA-ATP 吸附的溶解态 Phe 平均比例达到 90.55%，降低了上覆水中溶解态 Phe 的浓度。此外，即使颗粒态 Phe 被蟹生物扰动再悬浮，HA-ATP 也因其抑制解吸的能力而固定颗粒态 Phe，从而达到降低上覆水中 Phe 浓度的目的。这一结果得到了对 HA-ATP 吸附-解吸特性研究的证实。该研究为降低农业环境风险、提高水稻作物质量提供了一种环保型原位修复方法。
