Soil and groundwater contamination with lead (Pb) poses serious challenges for the environment. Activated carbon (AC) and biochar have huge potential application in the in-situ remediation processes through permeable reactive barriers (PRB). Spectral induced polarization (SIP) technique recently showed promises in nondestructively monitoring the spatio-temporal characteristics of physical, chemical and biological processes in porous media. In this study SIP technique was used for monitoring Pb remediation by AC and biochar in column scale. The calculated characteristic grain/pore size evolutions from SIP signals on AC, agreed well with the size of precipitates measured by SEM and mercury intrusion porosimetry (MIP) methods. The content increment process of the retained Pb on AC was also recorded via the magnitude increment of the imaginary conductivity. The mechanisms of Pb–AC and Pb-biochar interactions were investigated using SEM-EDS, TEM, FTIR, XRD, and XPS measurements. It showed that AC immobilizes through physical adsorption and precipitation, whereas complexation with functional groups is the remediation mechanism for biochar. Furthermore, the observed SIP responses of both AC and biochar are two orders of magnitude higher than those of typical natural soils or silica materials. This distinct difference is an additional advantage for the field application of SIP technique in PRB scenarios.

铅对土壤和地下水的污染对环境构成了严峻挑战。活性炭（AC）和生物炭通过可渗透的反应性屏障（PRB）在原位修复过程中具有巨大的潜力。光谱诱导极化（SIP）技术最近在无损监测多孔介质中物理，化学和生物过程的时空特征方面显示出了希望。在这项研究中，SIP技术用于监测柱规模的AC和生物炭对Pb的修复。根据交流电上SIP信号计算出的特征晶粒/孔尺寸演变，与通过SEM和压汞法测量的沉淀物尺寸非常吻合。AC上残留的Pb的含量增加过程也通过假想电导率的幅度增加来记录。使用SEM-EDS，TEM，FTIR，XRD和XPS测量研究了Pb-AC和Pb-生物炭相互作用的机理。结果表明，AC通过物理吸附和沉淀来固定，而与官能团的络合是生物炭的修复机制。此外，观察到的AC和生物炭的SIP响应比典型的天然土壤或二氧化硅材料的响应高两个数量级。对于PRB场景中SIP技术的现场应用，这种明显的不同是另一个优势。结果表明，AC通过物理吸附和沉淀来固定，而与官能团的络合是生物炭的修复机制。此外，观察到的AC和生物炭的SIP响应比典型的天然土壤或二氧化硅材料的响应高两个数量级。对于PRB场景中SIP技术的现场应用，这种明显的不同是另一个优势。结果表明，AC通过物理吸附和沉淀来固定，而与官能团的络合是生物炭的修复机制。此外，观察到的AC和生物炭的SIP响应比典型的天然土壤或二氧化硅材料的响应高两个数量级。对于PRB场景中SIP技术的现场应用，这种明显的不同是另一个优势。