The Key Lab of Resource Environment and GIS, College of Resource Environment and Tourism, Capital Normal University, Beijing 100048, China.
The Key Lab of Resource Environment and GIS, College of Resource Environment and Tourism, Capital Normal University, Beijing 100048, China.
J Environ Sci (China). 2016 Apr;42:112-118. doi: 10.1016/j.jes.2015.06.019. Epub 2015 Nov 11.
Protons (H(+)) as well as different major and trace elements may inhibit cadmium (Cd) uptake in aquatic organisms and thus alleviate Cd toxicity. However, little is known about such interactions in soil organisms. In this study, the independent effects of the cations calcium (Ca(2+)), magnesium (Mg(2+)), potassium (K(+)), H(+) and zinc (Zn(2+)) on Cd toxicity were investigated with 5-day long barley root elongation tests in nutrient solutions. The tested concentrations of selected cations and trace metal ions were based on the ranges that occur naturally in soil pore water. The toxicity of Cd decreased with increasing activity of Ca(2+), Mg(2+), H(+) and Zn(2+), but not K(+). Accordingly, conditional binding constants were obtained for the binding of Cd(2+), Ca(2+), Mg(2+), H(+), and Zn(2+) with the binding ligand: logK(CdBL) 5.19, logK(CaBL) 2.87, logK(MgBL) 2.98, logK(HBL) 5.13 and logK(ZnBL) 5.42, respectively. Furthermore, it was calculated that on average 29% of the biotic ligand sites needed to be occupied by Cd to induce a 50% decrease in root elongation. Using the estimated constants, a biotic ligand model was successfully developed to predict the Cd toxicity to barley root elongation as a function of solution characteristics. The feasibility and accuracy of its application for predicting Cd toxicity in soils were discussed.
质子 (H(+)) 以及不同的主要和痕量元素可能会抑制水生生物对镉 (Cd) 的吸收，从而减轻 Cd 的毒性。然而，对于土壤生物中的这种相互作用，人们知之甚少。在这项研究中，我们通过在营养液中进行为期 5 天的大麦根伸长试验，研究了阳离子钙 (Ca(2+))、镁 (Mg(2+))、钾 (K(+))、H(+) 和锌 (Zn(2+)) 对 Cd 毒性的独立影响。所选阳离子和痕量金属离子的测试浓度基于土壤孔隙水中自然存在的浓度范围。随着 Ca(2+)、Mg(2+)、H(+) 和 Zn(2+) 的活性增加，Cd 的毒性降低，但 K(+) 没有。因此，获得了 Cd(2+)、Ca(2+)、Mg(2+)、H(+) 和 Zn(2+) 与配体结合的条件结合常数：logK(CdBL) 5.19、logK(CaBL) 2.87、logK(MgBL) 2.98、logK(HBL) 5.13 和 logK(ZnBL) 5.42。此外，据计算，平均需要 29% 的生物配体位点被 Cd 占据，才能导致根伸长减少 50%。使用估计的常数，成功地开发了一个生物配体模型，以预测 Cd 对大麦根伸长的毒性作为溶液特性的函数。讨论了其在预测土壤中 Cd 毒性方面的可行性和准确性。
