底泥生长基质中重金属的迁移特征及生物有效性

河道底泥中重金属含量较高，重金属的迁移性及生物有效性是限制疏浚底泥土地施用或用作废弃场地修复基质资源化利用途径的主要因素。以沈阳细河待疏浚底泥为材料，通过盆栽实验的方法研究了河道底泥与碱性粉煤灰、炉渣和锯木屑配比基质中重金属在紫花苜蓿体内累积、迁移及生物有效性的变化。结果发现，配比底泥基质上紫花苜蓿生物量、株高及株径均好于纯底泥处理，其中底泥、粉煤灰、炉渣、锯木屑以2：0．5：0．5：0．5配比的s2处理中紫花苜蓿生物量是纯底泥处理的11．7倍。与底泥对照相比，配比底泥基质上植株体内重金属含量极显著降低，而且地上部重金属含量显著低于根部含量；底泥基质中紫花苜蓿地上部和根部对Cd、Cu、Pb、Zn的富集系数（BCF）显著低于底泥处理，但转移系数（TF）无显著变化，富集系数（BCF）和转移系数（TF）均小于1．0。紫花苜蓿种植后底泥基质中重金属含量显著低于农用污泥重金属控制标准，除Cd含量略高外，Cu、Pb和Zn含量低于土壤环境质量三级标准。这些结果表明，城市重污染河道底泥经过合理处置后，重金属浓度、活性及生物有效性降低，在其土地施用或废弃地修复中可以用作一些耐性植物的生长基质。

Transport and bioavailability of Cd, Cu, Pb and Zn in sediment substrate

Polluted sediment of Xi River has high heavy metal content, and the transport and bioavailability of heavy metals in dredged sediment is the major limitation for its land application and resource utilization in spoil areas. A pot experiment was conducted to study the accumulation, transport and bioavailability of heavy metals in Alfalfa of sediment substrate. The results showed that plant height, stem diameter and dry biomass values of Alfalfa of sediment substrate treatments were higher than those of sediment alone treatment. Moreover, the bio- mass value of Alfalfa of $1 treatment （the mixture of sediment, fly ash, boiler slag and wood sawdust by 2：0.5 ： 0.5：0.5 ） was 11.7 times of sediment alone treatment. Concentrations of heavy metals and the bioconcentration factor （BCF） in Alfalfa were significantly decreased in sediment substrate treatments, campared with sediment a- lone treatment, and the contents of Cd, Pb, Cu, Zn in root of plant were significantly greater than those in over- ground part. Bioconcentration factor （BCF） and translocation factor （TF） of overground part and underground part in sediment substrates were all lower than 1. O. Additionaly, the heavy metals concentrations in sediment substrate treatments after planting Alfalfa were lower than the control standards for pollutants in sludges from agri- cultural use and environmental quality standard for soils （ III ） （except Cd）. These results indicated that the pol- luted sediment after mixing with alkaline materials could be used as planting substrate for tolerant plants in land application or mine areas remediation.