Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
School of Resources and Environment, University of Jinan, Jinan 250022, China.
Int J Environ Res Public Health. 2019 Jan 18;16(2):264. doi: 10.3390/ijerph16020264.
Phytotoxicity thresholds for heavy metals are derived from dose⁻response curves, which show the relationships between exposure dose and toxicity response. However, the results of tests or observations are commonly based on total heavy metal concentration, not the exposure dose that causes phytotoxicity; additionally, the phytotoxicity response differs with plant species. In the present study, the ethylenediaminetetraacetic acid (EDTA)-extractable copper (Cu) concentration was determined in order to evaluate Cu extractability. As two important horticultural food crops in Asia, tomato ( 'Meifen No. 1') and bok choy ( var. 'Susheng 28') were used to investigate Cu phytotoxicity in a wide range of Chinese soils with and without leaching treatment, after which relationships between Cu phytotoxicity thresholds based on EDTA-extractions and soil properties were established. The phytotoxicity thresholds showed that biomass of bok choy was more sensitive to Cu than tomato. Multiple linear regression analyses showed that soil factors, including organic carbon (OC), citrate dithionate extractable manganese (CD-Mn), cation exchange capacity (CEC), and CaCO₃ explained over 85% of the variance in Cu phytotoxicity thresholds. The EDTA-extractable Cu dose⁻response relationships were further improved by incorporating soil properties. The new phytotoxicity predictive models indicated soil properties (soil pH, OC, CEC, and oxalate-extractable Mn) and EDTA-extractable Cu concentration explained more than 90% of the variance in the phytotoxicity response of tomato and bok choy biomass. The new phytotoxicity predictive models could be used to develop a reasonable remediation strategy for contaminated soils.
重金属的植物毒性阈值是通过剂量-反应曲线得出的，该曲线显示了暴露剂量与毒性反应之间的关系。然而，测试或观察的结果通常基于重金属的总浓度，而不是引起植物毒性的暴露剂量；此外，植物毒性反应因植物物种而异。本研究通过测定乙二胺四乙酸（EDTA）可提取铜（Cu）浓度来评估 Cu 的可提取性。番茄（‘美粉 1 号’）和菜心（var.‘苏生 28’）是亚洲两种重要的园艺食用作物，本研究通过测定无淋洗和淋洗处理的中国土壤中 EDTA 可提取铜浓度，评估了铜在不同土壤中的植物毒性，并建立了基于 EDTA 提取的铜毒性阈值与土壤性质之间的关系。铜毒性阈值表明，菜心的生物量对 Cu 的敏感性强于番茄。多元线性回归分析表明，土壤因子（有机碳（OC）、柠檬酸二硫代丁二酸盐可提取锰（CD-Mn）、阳离子交换量（CEC）和 CaCO₃）解释了铜毒性阈值变异的 85%以上。将土壤性质纳入 EDTA 可提取 Cu 的剂量-反应关系后，进一步提高了预测能力。新的植物毒性预测模型表明，土壤性质（土壤 pH 值、OC、CEC 和草酸盐可提取 Mn）和 EDTA 可提取 Cu 浓度解释了番茄和菜心生物量对植物毒性响应的 90%以上的变异。新的植物毒性预测模型可用于制定合理的污染土壤修复策略。
