Almås Asgeir R, Lombnaes Peder, Sogn Trine A, Mulder Jan
Department of Plant- and Environmental Sciences, Norwegian University of Life Sciences, P.O. Box 5003, N-1432 As, Norway.
Chemosphere. 2006 Mar;62(10):1647-55. doi: 10.1016/j.chemosphere.2005.06.020. Epub 2005 Aug 9.
A pot experiment was carried out to investigate the impact of Cd and Zn extractability in soil and speciation in pore water of industrial contaminated soils, on metal concentration in a metal sensitive species like spinach (Spinacia oleracea) and a more metal tolerant species like Italian ryegrass (Lolium multiflorum). For chemical speciation of Cd and Zn in pore water, WHAM/Model VI version 6.0 was used. The DGT technique was used to determine the effective concentration, C(E), of Cd and Zn in soils. The free ion activity in pore water correlated well with the contents in plants, and there was a linear relationship between the C(E) values and the concentration of Cd and Zn in both spinach and ryegrass in the non-toxic range. However, the C(E) values usually overestimated the plant contents when plants, particularly the spinach plants, were subjected to toxic concentration in the pore water. Metal uptake decreased in plants affected by toxicity, whereas metal binding to the Chelex resin did not. Thus, we found no linear relationship between the C(E) and metal contents in spinach, whereas a linear relationship was found between C(E)-Zn and the Zn concentration in ryegrass (r2=0.96, p<0.001). For Cd in ryegrass this relationship was weak (r2=0.53, p=0.18). This study indicates that the transport of metals from labile metal pools to the DGT-resin is linearly related to plant uptake only when plants are growing well, and that the applicability of DGT as an indicator for plant uptake seems species dependent.
进行了一项盆栽试验，以研究工业污染土壤中镉（Cd）和锌（Zn）的土壤提取率及孔隙水中的形态，对菠菜（Spinacia oleracea）这种对金属敏感的物种和多花黑麦草（Lolium multiflorum）这种更耐金属的物种中金属浓度的影响。对于孔隙水中Cd和Zn的化学形态分析，使用了WHAM/Model VI 6.0版本。采用DGT技术测定土壤中Cd和Zn的有效浓度C(E)。孔隙水中的自由离子活性与植物中的含量相关性良好，在无毒范围内，C(E)值与菠菜和黑麦草中Cd和Zn的浓度之间存在线性关系。然而，当植物，尤其是菠菜植株，在孔隙水中受到有毒浓度影响时，C(E)值通常会高估植物中的含量。受毒性影响的植物中金属吸收量下降，而金属与螯合树脂的结合量则没有下降。因此，我们发现菠菜中C(E)与金属含量之间不存在线性关系，而在黑麦草中C(E)-Zn与Zn浓度之间存在线性关系（r2 = 0.96，p < 0.001）。对于黑麦草中的Cd，这种关系较弱（r2 = 0.53，p = 0.18）。本研究表明，只有当植物生长良好时，从不稳定金属库到DGT树脂的金属迁移才与植物吸收呈线性相关，并且DGT作为植物吸收指标的适用性似乎取决于物种。
