Abstract:The toxicity thresholds (ECx, x=10,50, the effective concentration causing 10% and half inhibition) of Zn in sixteen Chinese soils were determined using log-logistic distribution models with four different toxicity bioassay endpoints, i.e., the potential nitrification rate (PNR) test, the barley root elongation assay (BRE), tomato (TGT) and bok choy (BGT) phytotoxicity test respectively, the quantitative relationship between the ECx of Zn in soils and the main physic-chemical (e.g. pH, CEC and org-C etc) was also quantitatively measured, and the toxicity based predicted models of Zn in soils were developed. The results indicated that toxicity thresholds of Zn varied significantly among the different bioassay endpoints. The toxicity thresholds of EC10 of bok choy growth toxicity, barley root elongation, tomato growth toxicity and potential nitrification rate test were 322, 356, 336及297mg/kg, respectively, the lowest EC10 was observed with potential nitrification rate test while the highest with barley root elongation test. The determined EC50 of the same order of bioassay endpoints were 846, 1471, 1160 and 768mg/kg respectively. In general, the sensitivity of the bioassay endpoints followed the order of: the potential nitrification rate test> tomato phytotoxicity test > bok choy phytotoxicity test> the barley root elongation test, while the test stability reversed. The result implied that the microbe were the most sensitive organism responded to the Zn toxicity and the tomato was the most sensitive plant among the tested crops. In terms of the applicability, the EC50 values were more sensitive than that of EC10, while the larger variation coefficient was observed with EC10 test. The pH value was the most important factor affecting the bioavailability of Zn in soils; the environmental risk can be well predicted by the normalization models developed on the pH, CEC and organic carbon contents of the soils.
陈世宝, 林蕾, 魏威, 刘继芳, 马义兵 . 基于不同测试终点的土壤锌毒性阈值及预测模型[J]. 中国环境科学, 2013, 33(5): 922-930.
CHEN Shi-Bao, LIN Lei, WEI Wei, LIU Ji-Fang, MA Yi-Bing- . Comparative study of Zn-toxicity thresholds in 16 Chinese soils as determined by different bioassay endpoints and its predicted models. CHINA ENVIRONMENTAL SCIENCECE, 2013, 33(5): 922-930.