生物炭溶解性有机质与Cd、Cu的结合作用及其垂向共迁移机制

Biochar has now become a hot research subject in the field of environment protection, because it has shown a good potential for application in the remediation of contaminated soils. When applied to soil, biochar can release its dissolved organic matter (DOM). Due to its high reactivity and mobility, DOM may extensively affect the mobility of heavy metals. In this proposed study, DOM dissolved from ranges of different precursor materials derived biochar will be reacted with Cd and Cu as target heavy metals, respectively. Advanced techniques such as fluorescence excitation-emission matrix combined with parallel factor analysis (EEM-PARAFAC), two dimensional FTIR correlation spectroscopy, NICA-Donnan model, HYDRUS software are to be applied to: (1) characterize the biochar-derived DOM and identify the components of DOM; (2) interpret molecular binding character of the biochar-derived DOM with Cd, Cu; (3) analyze the effects of different aquatic factors (pH and iron intensity) on the leaching behavior of DOM and Cd, Cu; (4) establish a vertical co-transport model of DOM and Cd, Cu. These results will be help to reveal the binding and vertical co-transport mechanisms of biochar-derived DOM with Cd and Cu, thus provide the scientific basis for evaluating the environment risk of biochar application in the remediation of heavy metal contaminated soils.

生物炭是近年来环保研究领域的关注热点，在土壤修复方面表现出巨大的应用潜力。生物炭自身携带的溶解性有机质（DOM）会伴随着生物炭的施用进入土壤。由于这些DOM具有高度的反应性与迁移性，可对土壤中重金属的迁移行为起着十分重要的调控作用。本项目拟以生物炭DOM为切入点，选择土壤典型重金属Cd、Cu为目标污染物，应用三维荧光光谱-平行因子分析、二维相关红外光谱、NICA-Donnan模型、HYDRUS溶质运移模拟软件等方法技术，对不同前体材料制备的生物炭提取的DOM进行性质表征与组分鉴别，深入研究生物炭DOM与Cd、Cu的分子结合特征，分析不同pH、离子强度条件对生物炭DOM与Cd、Cu共迁移的影响，建立生物炭DOM与Cd、Cu的垂向共迁移模型。本研究旨在揭示生物炭DOM与Cd、Cu的结合作用及其垂向共迁移机制，并为科学评价生物炭用于重金属污染土壤修复的环境风险提供理论依据。

生物炭自身携带的溶解性有机质（DOM）具有高度的反应性与迁移性，可对土壤中重金属的迁移行为起到重要调控作用。本项目选择菜籽饼、菊芋秸秆、玉米秸秆这些纤维素类生物质前体材料，采用厌氧控温炭化法于300、500、700℃条件下制备生物炭，并分别提取DOM。通过三维荧光光谱-平行因子分析、傅里叶变换红外光谱、同步辐射软X射线近边吸收谱等多种光谱学技术的应用，在分子尺度上精细表征了不同种类生物炭释放DOM的性质特征，明确了不同种类生物炭DOM与目标重金属的结合特征，并阐明了热解温度对生物炭DOM性质及其与重金属（Cd、Cu）结合的影响作用。结合室内柱垂向淋溶实验与HYDRUS溶质运移模型模拟，明确了生物炭DOM与目标重金属的共迁移特征，揭示了生物炭DOM性质特征对重金属发生垂向共迁移行为的影响规律。研究成果可为科学评价生物炭材料用于重金属污染土壤稳定化修复的潜力及其潜在的环境风险提供理论依据。