基质诱导硝化测定的土壤中锌的毒性阈值、主控因子及预测模型研究

Toxicity Threshold of Zn and Its Predictable Models as Determined by Induced Nitrification in Soils

选取我国有代表性的16种土壤,通过基质诱导硝化(SIN)的方法,研究了淋洗与未淋洗处理后,土壤中外源Zn对不同土壤潜在硝化速率(PNR)的影响。结果表明:在未淋洗处理土壤中Zn毒性的EC50(使PNR降低至对照一半土壤中Zn的浓度)值的范围为197～1874mg·kg-1,相差近9.51倍;总体而言,土壤pH、有机碳及粘粒含量的提高可以降低土壤中Zn的毒性。偏相关分析结果表明,影响土壤中Zn对潜在硝化速率抑制作用的主要因子依次为土壤pH、有机碳含量及粘粒含量;淋洗处理明显提高了土壤中外源Zn的毒性阈值浓度,在不同土壤中,淋洗因子(定义为淋洗后的土壤Zn毒性的EC50与非淋洗EC50的比值)范围为1.16～1.43;基于土壤主要性质的多元回归预测模型结果表明,利用土壤性状(pH、有机碳和粘粒含量)可以很好地预测土壤中Zn对硝化速率抑制的毒性阈值。

Sixteen different soils, representative of the soils in China, were selected for an experiment on measuring the toxicity of added Zn to potential nitrification rate （PNR） based on induced nitrification （SIN）. The resuits showed that the toxicity threshold of ECs0（as defined as effective concentration of added Zn causing 50% inhibition） ranged from 197 to 1 874 mg ·kg-1 in unleached soils as determined by SIN test, with nearly 9.51-fold variation among the EC50. In general, the toxicity of Zn in soils could be decreased with increment of pH, organic carbon, and clay minerals of soils. The result of partial correlation analysis indicated that the main factors affecting the toxicity threshold of Zn in soils follow the order ofpH 〉organic carbon 〉clay content in soils as determined by SIN test. Leaching treatment can significantly increase the ECs0 in soils with the leaching factors （LF, defined as ratio of EC50 after leaching to the ECs0 ofunleached soils） ranged from 1.16 to 1.43. The developed regression model based on the main soil properties （i.e. pH, organic carbon, and clay mineral contents） can accurately predict the Zn toxicity in the soils as determined by SIN test in this study.