A Pots Experimental Study On Remediation With Phosphate On Historical Pb-Zn Smelting Slag Polluted Soil In Northwestern Guizhou Province

The heavy metal contamination to the soil which induces the threat to the health of human beings is paid much attention to in recent years.The Northwestern Guizhou Province is a famous place for its long history in Pb-Zn smelting.Pb-Zn smelting discharges large amounts of lead,zinc,cadmium,copper,which has a potential risk to human beings and crops.Through field investigation,sampling,and analyses for heavy metals contents in contaminated soil,s and plants,results showed that the soils and plants in the historical zinc smelting areas were polluted seriously by heavy metals.Many specialists and scholars study the status which the soil enzymatic activities were affected by heavy metals in soil.The results indicated that the heavy metals inhibited the soil enzymatic activities.So the soil enzymatic activities mensurated were for knowing the status which the soil enzymatic activities and the quality of the soil were affected by heavy metals.On the basis of investigation and study for the polluted status of heavy metals in historical zinc smelting areas in northwestern guizhou province,based on previous pot experiments conducted by Li,the soil and slag were mixed in the ratio of 1:1 in pots,and the maize pots remediation experiment were followed to further constrain the ratios of phosphorus to soil.KH₂PO₄ were added to the mixed soils in the ratio of 8.61 mg/kgP,9.72 mg/kgP,10.83 mg/kgP,11.94 mg/kgP,13.05 mg/kgP,14.16 mg/kgP,15.27mg/kgP and 16.38 mg/kgP.According to the maize pots experiment results,the main results were summarized as follows:1.The content of heavy metals in smelting slag did not affected the maize germination rate too much,but greatly inhibited growth of the maize by lowering its height and weight.By a mult-iple linear regression analysis,the results showed that the content of available Cd inhibited growth of the maize by lowering its height and weight strong-lier than Zn,Pb and Cu.2.The results of the maize pots experimental showed KH₂PO₄ addition amounts to soil in the ratio of 13.5±0.5 is better to inhibite soils and plants contaminated by heavy metals.3.The Cu,Pb,Zn,Cd in Pb-Zn smelting slag could all inhibite the soil enzymatic activities including the phosphatase activities,the urease activities and the calatas(?) activities.By a multiple linear regression analysis,by combined pollution of heavy metals, the results showed that the soil enzymatic activities were significantly related to the combined content of available heavy metals.The content of available Cd inhibited the soil enzymatic activities stronglier than Zn,Pb and Cu.The content of heavy metals availability in smelting slag was high,so the soil enzymatic activities were not enhanced in the maize pots experimental.