Ghent University, Faculty of Bioscience Engineering, Department of Applied Analytical and Physical Chemistry, Coupure Links 653, Ghent 9000, Belgium.
Ghent University, Faculty of Bioscience Engineering, Department of Applied Analytical and Physical Chemistry, Coupure Links 653, Ghent 9000, Belgium.
Sci Total Environ. 2018 Jun 1;626:195-202. doi: 10.1016/j.scitotenv.2018.01.054. Epub 2018 Feb 19.
To determine the long-term impact of organic amendments on metal (Cd and Zn) immobilization, soil from the Campine region was amended with holm oak-derived biochar, compost, and peat, and monitored over a 3-year period. Pot experiments were conducted by mixing the amendments independently at 2% and 4% (g/g) with the soil. The mobility and solubility of metals in the treatments were assessed by means of rhizon soil moisture samplers, sequential BCR extractions, and diffusive gradient in thin films (DGT). Over the three-year period, the 2% biochar addition resulted in an average decrease in pore water concentration of 40% for Cd and 48% for Zn whereas the 4% addition led to an average decrease of 66% for Cd and 77% for Zn. The immobilization effect in the biochar treatments was attributed to the consistently higher pH and lower concentrations of dissolved organic carbon (DOC) in the soil. The latter may have been caused by sorption of DOC onto the surface of biochar thereby increasing its negatively charged functional groups that are able to sorb cations. On the other hand, compost and peat had the unwanted effect of significantly increasing the concentrations of Cd and Zn in the soil pore water. This was partly due to the formation of soluble organo-metallic complexes as significantly higher DOC concentrations were found in the compost and peat treatments. Results from the DGT measurements, after a 24 h deployment time, revealed a low resupply (R ≤ 0.4) of Cd and Zn from the solid phase to the soil solution in both amended and unamended soil. This suggests a case of slow metal desorption kinetics in the soil that was relatively unchanged by the presence of organic amendments.
为了确定有机改良剂对金属（Cd 和 Zn）固定化的长期影响，用来自 Holm 橡树的生物炭、堆肥和泥炭对坎皮纳地区的土壤进行了改良，并在 3 年的时间里进行了监测。通过将改良剂分别以 2%和 4%（g/g）与土壤混合，进行了盆栽实验。通过 rhizon 土壤水分采样器、顺序 BCR 提取和薄膜扩散梯度（DGT）评估了处理中金属的迁移性和溶解度。在三年的时间里，2%生物炭的添加导致 Cd 的孔水浓度平均降低了 40%，Zn 的浓度平均降低了 48%，而 4%的添加导致 Cd 的浓度平均降低了 66%，Zn 的浓度平均降低了 77%。生物炭处理中的固定化效应归因于土壤中 pH 值始终较高和溶解有机碳（DOC）浓度较低。后者可能是由于 DOC 吸附在生物炭表面，从而增加了能够吸附阳离子的带负电荷的官能团。另一方面，堆肥和泥炭却产生了意想不到的效果，显著增加了土壤孔隙水中 Cd 和 Zn 的浓度。这部分是由于形成了可溶性有机金属络合物，因为在堆肥和泥炭处理中发现了更高的 DOC 浓度。在 24 小时部署时间后，DGT 测量结果表明，在添加和未添加有机改良剂的土壤中，从固相到土壤溶液中 Cd 和 Zn 的再供应（R≤0.4）较低。这表明土壤中金属解吸动力学较慢，而有机改良剂的存在并没有改变这种情况。
