Martz Melanie, Heil Jannis, Marschner Bernd, Stumpe Britta
Department of Human & Environmental Research, Institute of Geography, Bergische Universität Wuppertal, Gaußstraße 20, 42119 Wuppertal, Germany.
Department of Human & Environmental Research, Institute of Geography, Bergische Universität Wuppertal, Gaußstraße 20, 42119 Wuppertal, Germany.
Sci Total Environ. 2019 Jul 1;672:162-173. doi: 10.1016/j.scitotenv.2019.03.369. Epub 2019 Mar 30.
Subsoils control the release of hydrophobic pollutants to groundwater systems, but the role of subsoil soil organic carbon (SOC) in sorption processes of hydrophobic organic pollutants remains unclear. Thus, this study aimed to understand the role of subsoil SOC in sorption processes of 4-n-nonylphenol (NP) and perfluorooctanoic acid (PFOA) as model pollutants. To characterize the sorption behavior of NP and PFOA, 42 sub- and 54 topsoil samples were used for batch experiments. Differences in NP and PFOA sorption between sub- and topsoil samples and its mechanisms were identified using multiple regression analysis. Generally, the sorption of NP and PFOA was linear in all samples. The sorption of NP to soil samples (log = 1.78-3.68) was significantly higher and less variable than that of PFOA (log = -0.97-1.44). In topsoils, SOC content had the highest influence on NP and PFOA sorption. For NP, hydrophobic interactions between NP and SOC were identified as the most important sorption mechanism. For PFOA, hydrophobic as well as electrostatic interactions were determined depending on soil pH. In subsoils, the relevance of SOC content for pollutant sorption decreased drastically. For NP, not SOC content but rather SOC quality was relevant in SOC poor subsoils. For PFOA, clay and iron oxide content were found to be relevant for pollutant interactions with the solid phase. Thus, especially in SOC depleted subsoils, the sorption potential for PFOA remained unpredictable.
底土控制着疏水性污染物向地下水系统的释放，但底土有机碳（SOC）在疏水性有机污染物吸附过程中的作用仍不清楚。因此，本研究旨在了解底土SOC在作为模型污染物的4-正壬基酚（NP）和全氟辛酸（PFOA）吸附过程中的作用。为了表征NP和PFOA的吸附行为，使用了42个底土样本和54个表土样本进行批量实验。使用多元回归分析确定了底土和表土样本之间NP和PFOA吸附的差异及其机制。一般来说，NP和PFOA在所有样本中的吸附都是线性的。NP在土壤样本上的吸附（log = 1.78 - 3.68）显著高于PFOA（log = -0.97 - 1.44），且变化较小。在表土中，SOC含量对NP和PFOA吸附的影响最大。对于NP，NP与SOC之间的疏水相互作用被确定为最重要的吸附机制。对于PFOA，根据土壤pH值确定疏水和静电相互作用。在底土中，SOC含量对污染物吸附的相关性急剧下降。对于NP，在SOC含量低的底土中，与SOC含量相比，SOC质量更为重要。对于PFOA，发现粘土和氧化铁含量与污染物与固相的相互作用有关。因此，特别是在SOC耗尽的底土中，PFOA的吸附潜力仍然无法预测。
