State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.
State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.
Water Res. 2019 May 1;154:210-216. doi: 10.1016/j.watres.2019.01.060. Epub 2019 Feb 15.
Dissolved black carbon (DBC) involves in many biogeochemical processes in both terrestrial and aquatic environments. About 26.5 Tg of charcoal- or black carbon-derived DBC was released into aquatic environments annually, accounting to ∼10% of the global riverine flux of dissolved organic carbon (DOC). Yet the sorption behaviors of DBC and their effects on water quality in soil-water environment are poorly understood. Here we examined the molecular composition variations of DOC induced by the sorption of two biochar-derived DBCs (pyrolyzed at 300 °C and 500 °C) on three contrasting soils. The DBCs were adsorbed mainly through competitive displacement of soil surface functional groups and co-sorption with soil indigenous DOC, which varied with soil properties and the aromaticity of the DBCs. Ultrahigh resolution mass spectrometry analysis indicated that compounds with rich oxygen content or unsaturated structures such as tannins and unsaturated aromatics from both DBC and soil DOC, were preferentially adsorbed on the soils in the presence of DBC. In contrast, compounds with high aromatic structures including condensed aromatics and lignins were concentrated in the aquatic phase. Molecular fractionation also occurred to the heteroatomic compounds during the sorption, and the heteroatomic dissolved organic sulphur in the DBCs was easier to be adsorbed relative to dissolved organic nitrogen. Our results suggest that DBC sorption in soil-water environment could have important implications for water quality by altering DOC molecular composition and decreasing DOC molecular diversity at the soil-water interface. This study provides essential information for understanding the behavior of DBC in the environments.
溶解态黑碳（DBC）参与了陆地和水生环境中的许多生物地球化学过程。每年约有 26.5 太克的木炭或黑碳衍生的 DBC 释放到水生环境中，约占全球河流溶解有机碳（DOC）通量的 10%。然而，DBC 的吸附行为及其对土壤-水环境水质的影响仍知之甚少。在这里，我们研究了两种生物炭衍生的 DBC（在 300°C 和 500°C 下热解）在三种不同土壤上吸附对 DOC 分子组成变化的影响。DBC 主要通过与土壤表面官能团的竞争置换和与土壤固有 DOC 的共吸附而被吸附，这与土壤性质和 DBC 的芳香度有关。超高分辩质谱分析表明，来自 DBC 和土壤 DOC 的富氧含量或不饱和结构的化合物，如单宁和不饱和芳烃，优先在 DBC 存在的情况下被土壤吸附。相比之下，具有高芳香结构的化合物，包括缩合芳烃和木质素，则集中在水相中。在吸附过程中，杂原子化合物也发生了分馏，DBC 中的杂原子溶解有机硫比溶解有机氮更容易被吸附。我们的研究结果表明，DBC 在土壤-水环境中的吸附可以通过改变 DOC 的分子组成和降低土壤-水界面处 DOC 的分子多样性，对水质产生重要影响。本研究为理解 DBC 在环境中的行为提供了重要信息。
