中文摘要：

【目的】随着对污染土壤管理要求的不断提高,受污染土壤生态风险评价的内容也在不断深入。目前,污染土壤风险评价毒性测试逐渐由单物种测试为基础的生态风险评价发展为基于物种敏感性分布的区域种群毒性测试;毒性中除了要包含测试物种的整个生命周期,还需要增加不同敏感的测试终点。基于不同测试终点的毒理学数据对于评价污染土壤中Zn的环境风险具有重要意义。根系生态是基于生态效应法推导土壤中重金属生态风险阈值的重要组成部分,论文中以大麦根尖数、总根长、根表面积和根平均直径为评价终点,研究污染土壤中Zn对大麦根微形态的毒性阈值及其与土壤性质间的量化关系,以期为中国Zn污染土壤的环境风险评价提供科学依据。【方法】采集了8种不同性质的农田土壤,外源添加不同浓度Zn后进行盆栽试验,利用STD1600 Epson根系扫描仪测定不同根微形态指标,结合Log-logistic剂量-效应曲线测定基于不同根微形态为终点的毒性阈值（EC_（10）,EC_（50））,建立基于土壤性质的Zn毒性预测模型。【结果】土壤Zn污染对不同根微形态指标的毒性阈值存在较大差异,基于大麦根尖数、总根长、根表面积和根平均直径的有机碳（EC_（10））和阳离子交换量EC_（50）均值分别为228、295、335、261 mg·kg~（-1）及702、779、837、739 mg·kg~（-1）,以根尖数测定的EC值最低,根表面积的EC值最高,即根尖数指标对土壤Zn毒性最敏感。不同土壤中,EC_（10）值的变异系数（34.1%）大于EC_（50）（21.6%）,而4种不同测试指标中,基于大麦根表面积测定的变异系数最大,EC_（10）和EC_（50）的变异系数分别达到43.4%和23.2%。土壤pH、有机碳（OC）、阳离子交换量（CEC）与Zn的毒性阈值EC_x（x=10,50）呈正相关关系,其中pH的相关系数达到极显著水平（P〈0.01）。【结论】不同的根微形态?

英文摘要：

[ Objective ] With the continuous requirements for the management of contaminated soil, intensive studies on the ecological risk assessment of contaminated soil are increasingly important. At present, the toxicity test based on species sensitivity distribution for ecological risk assessment of regional contaminated soil has been becoming more and more important compared with the toxicity test based on single species. The toxicity assay should include not only the test for throughout the life cycle, but also the sensitivity of different test endpoints. Toxicity thresholds of Zn determined with different test endpoints are important for evaluation of the environmental risk of Zn in polluted soils. Root ecology plays an important role in the ecological risk assessments and the derivation of toxicity thresholds of heavy metals in polluted soils. The Zn toxicity thresholds （ECx, x= 10, 50） of barley as determined by total root length, number of root tips, root surface area and the average diameter of barley root and the quantitative relationships between the ECx and soil properties were studied with the aim to provide basic data for environmental risk evaluation of Zn polluted soils. [ Method] Eight kinds of field soils with various properties were collected around China, Zn （ZnC12） was applied and the treated soils were used in a pot experiment after 4 weeks of incubation. Different micro morphological endpoints of barley roots were measured with root scanner （STD1600 Epson）, the Zn toxicity thresholds （ECx, x=10, 50） of barley were determined based on the dose-responsive curve with Log-logistic model, the prediction models of Zn toxicity thresholds were developed based on the total Zn concentrations and soil properties （e.g. pH, CEC and org-C etc）. [ Result ] The results indicated that toxicity thresholds of Zn varied significantly among the different micro morphological endpoints of barley roots. The average EC10 and ECs0 determined with total root length, number of root tips, root surface area