电镀废水污染水稻田土壤中重金属的形态分析

Fractionations of Heavy Metals in Paddy Soils Contaminated by Electroplating Wastewater

通过连续提取法对电镀废水污染区和对照区水稻田土壤中重金属元素Cu、Cr、Ni、Pb和Mn的形态进行了分析研究。结果显示,污染区土壤中多种形态的Cu、Cr和Ni含量都显著高于对照区,尤其以它们的有机结合态的差异最为显著。在污染区土壤中,有机结合态的Cu、Cr和Ni分别占总量的28.0%、58.2%和17.4%,而对照区土壤有机结合态的Cu、Cr和Ni分别仅为总量的9.6%、35.2%和9.2%。污染区较对照区土壤中Mn的总量虽无显著差异,但可交换态Mn的含量显著增加。污染区与对照区土壤中Pb的交换态、碳酸盐结合态和Fe-Mn氧化物结合态均无显著差异。电镀废水的污染使得水稻田土壤中Cu、Cr和Ni含量及其有效性显著升高,同时可导致Mn的化学形态发生改变,提高了Mn的移动性和生物有效性。

The fractionations of Cu, Cr, Ni, Pb and Mn in soil collected from contaminated paddy soils and non-contaminated paddy soils near an electroplating plant were investigated using the five-stage sequential extraction procedure. The experimental results indicated that the various fractions of Cu, Cr and Ni in the contaminated soil, especially the organic matter fractions, were significantly higher than those in the non-contaminated soil. The organic matter fractions of Cu, Cr and Ni were determined to be 28.0%, 58.2% and 17.4% of their total amounts in the contaminated soils, and only 9.6%, 35.2% and 9.2% in the non-contaminated soils, respectively. There was no significant difference in the total concentration of Mn between the contaminated and the non-contaminated soils. However, the exchangeable fraction of Mn in the contaminated soil was obviously higher than that in the non-contaminated soil. Moreover, no significant differences existed between the contaminated and the non-contaminated soils for the exchangeable fraction, the carbonate fraction and the iron-manganese oxides fraction of Pb. The results show the contamination of the electroplaling wastewater could significantly increase the concentration and the hioavailahility of Cu, Cr and Ni in the paddy soil and could simultaneously promote the transformation of Mn, which would enhance the mobility and bioavailability of Mn.