为测定水泥基河道底泥固化材料中4种重金属元素（Pb、Cu、Cr、Zn）的形态，作如下试验：将普通硅酸盐水泥与河道底泥按质量比2：8进行混合，并注装于模具中干燥成型后，于湿度>95%，温度为（20±0.5）℃条件下的养护箱内分别湿式养护3，7，14，28，45，60 d，制得一系列固化材料样品。作为分析用样品，须将固化块样破碎至通过75 μm孔径的网筛并充分混匀。测定上述样品中重金属元素总量时，取此经破碎的样品0.100 g，用硝酸3 mL，过氧化氢1 mL和氢氟酸1 mL进行微波消解。所得消解液于150℃加热蒸发赶酸，冷却后加水溶解并定容为50.0 mL。用电感耦合等离子体质谱法（ICP-MS）测定此溶液中4种重金属元素的含量。另取0.800 g样品，按改进的BCR连续提取法先后分离出上述4种重金属元素的4种结合形态，依次为酸可提取态（F1）、可还原态（F2）、可氧化态（F3）和残渣态（F4）。分离所得4种形态的样品溶液用ICP-MS分别测定其中重金属元素的含量。在ICP-MS分析中，用Sc、Ge、In和Bi作为内标，以校正响应信号的变化和消除仪器的漂移及基体效应。试验结果表明，所用方法具有较好的准确度和精密度。根据改进的BCR连续提取法分离后，ICP-MS的分析结果得到了固化过程中4种重金属元素迁移性变化的特征和规律。

For determination of combination state of 4 heavy metal elements (i.e., Pb, Cu, Cr, Zn) in solidified materials of cement-based river sediment, testing samples were prepared as follows:cement was mixed thoroughly with river sediment by the mass ratio of 2 to 8, and the mixture was dried and moulded into solid cubes, which were then wet-cured in curing boxes for 3, 7, 14, 28, 45 and 60 days at (20±0.5)℃ with relative humidity of >95%. For use as an analytical sample, the solid cube should be crashed to pass through sieve with pore of 75 μm. For determination of total content of the 4 heavy metal elements. 0.100 g of the crashed sample was taken and digested with 3 mL of HNO₃ and 1 mL each of H₂O₂ and HF in a microwave oven. The digested solution was then heated at 150℃ to expel acids, and after cooling the solution was diluted to 50.0 mL with water and used for ICP-MS determination. Another portion of 0.800 g of the sample was taken and treated by the modified BCR successive extractions to obtain 4 sample solutions containing the 4 heavy metal elements in 4 combination states, i.e., (F1) acid extractable state, (F2) reducible state, (F3) oxidizable state and (F4) residual state, and contents of the 4 heavy metals were determined by ICP-MS in the same way. In the MS analysis, Sc, Ge, In and Bi were chosen as internal standards to calibrate changes of response signals and to eliminate instrumental drifts and matrix effects. It was shown that the proposed method gave results satifactory in accuracy and precision, and that characteristics and regulations of migrations of the 4 elements during the course of solidification were found, based on data of ICP-MS analysis with separation by the modified BCR successive extraction method.