摘要:
本论文采用污泥和土壤外源铜的活性差异系数法研究了农用污泥中铜的生态安全阈值。首先通过比较确定不同土壤条件下污泥中铜和水溶性铜的活性差异的系数,然后利用系数法得到相应土壤条件下污泥铜HC5值(即能够保护95% 物种的浓度),并建立了土壤理化性质参数与污泥铜HC5值的量化关系和预测模型。最后与我国现行污泥农用标准值进行了比较,提出了修改建议。结果表明,土壤中来源污泥的铜活性均值约为来源水溶性盐的40% 左右。土壤阳离子交换量(CEC)是影响土壤中污泥源铜的毒性的主控因子,可影响污泥铜HC5值变异的84.6%,而土壤pH值和有机碳含量(OC)分别可影响污泥铜HC5值变异的8.4% 和1.8%。基于土壤pH、OC和CEC的三因子模型进行预测优于基于土壤pH和CEC的两因子模型,其相关性达到94.8%。与模型预测值相比,我国现行污泥农用标准GB4284-84与CJ/T309-2009中对铜限值的规定均存在着不同程度的保护不足或保护过度问题。
Abstract:
The approach of the difference in availability between copper added as soluble salts and sewage sludge in the same soilswas used to study the ecological thresholds for copper in sewage sludge used for agricultural soils.Firstly,the availability coefficients representing the difference in availabihty between copper added as soluble salts and sewage sludge in the same soils were compared,then the HC5(protecting 95% of species in ecosystem) values of copper in soils amended with sewage sludge as well as a function of soil physicochemical properties were established using the availability coefficient approach.Finally,the predicted values by the models with the corresponding values derived from current national control standards for copper in sludge from agricultural use were compared,and recommendations on copper criteria values were given.The results showed that the mobility of copper in sewage sludge accounts for about 40% of the one in soluble salts.Cation exchange capacity(CEC) was found to be the main factor controlling 84.6% variation of HC5 values in soils amended with sewage sludge,while soil pH and organic carbon content(OQ could explain the variation of HC5 values by 8.4% and 1.8%,respectively.When soil properties are available,using three factor model(soil pH,OC and CEQ,the coefficient of determination(R2) reached up to 94.8%,which is able to predict more accurately than two factor model(soil pH and CEC).In comparison with predicted values,both inadequate and excessive protection problem might exist in current national control standards.
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