土壤化学模型可有效地计算和预测元素的化学形态和分布，但对常见的重金属元素铅，其模拟计算与实验结果相差较大。本项目采用国际腐殖质学会（IHSS）的标准方法，提取纯化了吉林通化棕壤和湖北九宫山山地草甸土中的胡敏酸和富里酸，制备了针铁矿、赤铁矿、不同氧化度的水钠锰矿，虹吸法获得钙质的高岭石、蒙脱石胶体样品。建立了Mütek滴定法测定腐殖酸表面绝对电荷量的方法；利用酸碱滴定法，明确了腐殖酸表面电荷特性，通过NICA-Donnan模型优化了腐殖酸吸附质子的相关参数；探讨了铅离子选择电极测定Pb2+活度的方法，阐明了不同离子强度和pH条件下腐殖酸对Pb2+的吸附，模型计算结果与实测值相吻合；利用红外光谱测定了水钠锰矿对Pb2+吸附的光谱学特征，初步建立了锰氧化物的化学吸附模型；明确了针铁矿、赤铁矿表面所带电荷及其对Pb2+的吸附特性。在该项目的资助下，先后邀请国外专家4人次来访；以此项目为纽带，加强了与国际同行的联系，促进了国内土壤化学模型的发展与应用；发表和待发表SCI论文3篇。由于本项目仅有2年时间，虽然按要求基本完成了研究内容，有关数据处理还需要进一步开展，文章撰写与发表后续加强。

Soil chemical adsorption models can be of great use to calculate and predict the elemental speciation and distribution. In literatures, good agreement between model prediction and measured values has been found for many heavy metals, whereas, Pb is an exception among the common heavy metals. There is a big discrepancy between the model prediction and measured distribution of Pb. The humic acid (HA) and fulvic acid (FA) (HAs) studied were extracted and purified from brown soil in Jilin and meadow soil in Hubei following the IHSS standard method. Goethite, hematite and birnessite with different average oxidation state (AOS) were obtained from chemical reaction. Colloidal kaolinite and montmorillonite were prepared using sedimentation method. Absolute charge measurement of HA with Mütek titration was established. The charging properties of HAs were determined with acid-base titration, and proton adsorption on HAs was calculated with NICA-Donnan model. Methodology of measuring the activity of Pb2+ with ion selective electrode was optimized. Pb2+ adsorption on HAs was studied for different ionic strength and pH condition, and the model prediction with NICA-Donnan agrees well with the experimental data. Fourier transform infrared spectroscopy (FTIR) of birnessites with different Mn AOS before and after Pb2+ adsorption provided fundamental knowledge regarding the amount of vacant sites and the interaction mechanisms between Pb2+ and birnessite. The adsorption modeling for Pb2+ to Mn oxides was explored. Within the context of this project, two foreign experts were invited to visit the host group; cooperation with several international colleagues has been established; the domestic development and application of soil chemical modeling has been promoted; and three papers are published or accepted for this project. Although the research contents of the project are mostly finished, the relevant data processing requires some extra time, and preparation and publication of the remaining papers need to be accomplished in the near future.

土壤化学模型可有效地计算和预测元素的化学形态和分布，但对常见的重金属元素铅，其模拟计算与实验结果相差较大。本项目采用国际腐殖质学会（IHSS）的标准方法，提取纯化了吉林通化棕壤和湖北九宫山山地草甸土中的胡敏酸和富里酸，制备了针铁矿、赤铁矿、不同氧化度的水钠锰矿，虹吸法获得钙质的高岭石、蒙脱石胶体样品。建立了Mütek滴定法测定腐殖酸表面绝对电荷量的方法；利用酸碱滴定法，明确了腐殖酸表面电荷特性，通过NICA-Donnan模型优化了腐殖酸吸附质子的相关参数；探讨了铅离子选择电极测定Pb2+活度的方法，阐明了不同离子强度和pH条件下腐殖酸对Pb2+的吸附，模型计算结果与实测值相吻合；利用红外光谱测定了水钠锰矿对Pb2+吸附的光谱学特征，初步建立了锰氧化物的化学吸附模型；明确了针铁矿、赤铁矿表面所带电荷及其对Pb2+的吸附特性。在该项目的资助下，先后邀请国外专家4人次来访；以此项目为纽带，加强了与国际同行的联系，促进了国内土壤化学模型的发展与应用；发表和待发表SCI论文3篇。由于本项目仅有2年时间，虽然按要求基本完成了研究内容，有关数据处理还需要进一步开展，文章撰写与发表后续加强。