基于根伸长的典型叶类蔬菜 Se 生态风险

为探究硒(Se)对叶类蔬菜的毒性效应,文章通过水培实验,以18种典型叶类蔬菜萌发期的相对根伸长(relative root elongation, RRE)作为评测终点,采用Log-logistic、Hormesis模型确定典型叶类蔬菜的 $ EC_{20} $、 $ EC_{50} $,基于Burr-Ⅲ模型分析18种蔬菜Se敏感性差异并计算最大环境有害浓度(hazardous concentration for 5% of species, $ HC_{5} $)。结果表明:部分蔬菜无Se兴奋效应,部分蔬菜具有Se兴奋效应,兴奋效应质量浓度范围为0.1~5.0 mg/L,Se对蔬菜RRE的兴奋效应和毒害性与蔬菜种类密切相关;品种大白菜中白(DBCZ)、生菜孔雀菜(SCKQ)和空心菜竹叶(KXCZ)表现出较强的Se耐性,而品种茼蒿板叶(THBY)、茼蒿圆叶(THYY)和苋菜圆叶(XCYY)表现出较强的敏感性。不同蔬菜的Se毒性阈值差异明显, $ EC_{20} $和 $ EC_{50} $范围分别为0.48~10.59 mg/L和1.88~19.60 mg/L;兴奋效应显著影响蔬菜的剂量-效应关系,Se兴奋效应组的模型参数(最大与最小RRE差值a、毒害性变化速率b、 $ EC_{20} $和 $ EC_{50} $)平均值显著大于无兴奋效应组;保护95%蔬菜的20%效应毒性阈值( $ HC_{5}^{20} $)和50%效应毒性阈值( $ HC_{5}^{50} $)分别为0.29、1.20 mg/L,蔬菜种类对 $ HC_{5} $影响极大,敏感性品种缺失会导致 $ HC_{5} $显著提高,耐性品种缺失会一定程度上降低 $ HC_{5} $。

To explore the toxic effect of selenium(Se) on leafy vegetables, the toxicity thresholds $ EC_{20} $ and $ EC_{50} $ of 18 typical leafy vegetables were determined using Log-logistic and Hormesis models through a hydroponic experiment with their relative root elongation (RRE) during seed germination as test endpoint. Based on the Burr-III model, the sensitivity differences of the 18 vegetables to Se were analyzed and hazardous concentration for 5% of species ( $ HC_{5} $) was calculated. The results showed that some vegetables had no excitatory effect of Se, while some vegetables presented an excitatory effect of Se, with a concentration range of 0.1-5.0 mg/L. The excitatory effect and toxicity of Se on the RRE of vegetables were closely related to vegetable species. The cultivars DBCZ, SCKQ and KX-CZ were highly Se-tolerant, while THBY, THYY and XCYY were highly Se-sensitive. The Se toxicity thresholds of different vegetables were significantly different, with $ EC_{20} $ and $ EC_{50} $ ranging from 0.48 mg/L to 10.59 mg/L and 1.88 mg/L to 19.60 mg/L, respectively. The excitatory effect signifi