基于大麦根伸长测定土壤Pb毒性阈值、淋洗因子及其预测模型

选取了我国10个典型的不同性质农田土壤,外源添加8个不同Pb浓度，分别进行淋洗与非淋洗处理，根据ISO 11269-1根伸长毒性测试方法，测定了土壤外源Pb对大麦根伸长的毒性阈值(EC₁₀、EC₅₀)及Pb毒性的淋洗因子，同时建立了基于不同土壤性质的Pb毒性阈值预测模型. 结果表明: 不同性质土壤中Pb对大麦根伸长的毒性阈值有显著差异(P<0.01)，EC₅₀ 值在300～4130 mg·kg^-1，EC₁₀ 值在55～633 mg·kg^-1. 淋洗处理明显降低了土壤中外源Pb的毒性，基于EC₅₀和EC₁₀测定的不同土壤淋洗因子(LF_ECx)的变化范围分别为0.96～1.96(LF_EC50)和1.03～1.81(LF_EC10). 相比而言，在酸性(pH<6.81)土壤中，淋洗处理对降低土壤外源Pb的毒性作用更为明显. 基于主控因子(pH、有机碳含量OC、阳离子交换量CEC)的淋洗与非淋洗土壤中Pb的大麦根伸长毒性(EC_x,_x=10,50)预测模型表明，除了江西红壤外，淋洗与非淋洗土壤中Pb的EC₅₀实测值均落在模型预测值±2倍标准误差范围之内，说明基于上述土壤主要性质可以较好预测不同性质土壤中Pb的毒性阈值.

Toxicity thresholds and predicted model of Pb added to soils with various properties and its leaching factors as determined by barley root-elongation test.

Ten field soils with various properties were added with Pb at 8 levels, and treated with or without leaching using simulated rain to test the Pb toxicity threshold (EC_10, EC₅₀) according to the ISO 11269-1 root elongation toxicity testing method. The leaching factors of Pb toxicity to barley root elongation were determined and the predicted models of Pb toxicity thresholds in soils with various properties were developed. The results indicated that the determined toxicity threshold (EC₁₀, EC₅₀) of Pb varied significantly (P<0.01) among the soils, and the EC₁₀ and EC₅₀ of Pb to barley in the soils ranged from 300-4130 mg·kg^-1 and 55-633 mg·kg^-1, respectively. The Pb toxicity decreased sharply after leaching treatment. The determined leaching factors (LF) ranged from
0.96-1.96 (LF_EC50) and 1.03-1.81 (LF_EC10) respectively, and the obvious effect was observed for the Pb toxicity decreasing in the soils with pH<6.81. The predicted models for Pb toxicity thresholds in soils were developed based on main soil properties (soil pH, organic carbon content and cation exchange capacity), and the determined Pb toxicity thresholds (EC_x,x=10,50) in soils fell in the range of mean values with ± 2 standard error (SD) prediction interval for the leached and unleached soils except for the red soil of Jiangxi Province, which indicated that the models based on the main soil properties could well predict the Pb toxicity in soils with various soil properties.