Katoh Masahiko, Risky Elsya, Sato Takeshi
Department of Agricultural Chemistry, School of Agriculture, Meiji University, Kawasaki, Kanagawa 214-8571, Japan.
Department of Civil Engineering, Graduate School of Engineering, Gifu University, Gifu 501-1193, Japan.
Int J Environ Res Public Health. 2017 Oct 23;14(10):1273. doi: 10.3390/ijerph14101273.
This study conducted plant growth tests using a rhizobox system to quantitatively determine the distance of immobilization lead migrating from contaminated soil into uncontaminated rhizosphere soil, and to assess the lead phases accumulated in rhizosphere soil by sequential extraction. Without the hydroxyapatite, exchangeable lead fractions increased as the rhizosphere soil got closer to the contaminated soil. Exchangeable lead fractions were higher even in the rhizosphere soil that shares a boundary with the root surface than in the soil before being planted. Thus, plant growth of hairy vetch was lower in the soil without the hydroxyapatite than in the soil with the hydroxyapatite. The presence of hydroxyapatite may immobilize the majority of lead migrating from contaminated soil into the rhizosphere soil within 1 mm from the contaminated soil. The dominant lead fraction in the rhizosphere soil with the hydroxyapatite was residual. Thus, plant growth was not suppressed and the lead concentration of the plant shoot remained at the background level. These results indicate that the presence of hydroxyapatite in the rhizosphere soil at 5% wt may immobilize most of the lead migrating into the rhizosphere soil within 1 mm from the contaminated soil, resulting in the prevention of lead migration toward the root surface.
本研究使用根箱系统进行了植物生长试验，以定量测定固定化铅从污染土壤迁移到未污染根际土壤中的距离，并通过连续提取法评估根际土壤中积累的铅形态。在没有羟基磷灰石的情况下，随着根际土壤靠近污染土壤，可交换态铅含量增加。即使在与根表面相邻的根际土壤中，可交换态铅含量也高于种植前的土壤。因此，在没有羟基磷灰石的土壤中，毛苕子的植物生长低于有羟基磷灰石的土壤。羟基磷灰石的存在可能会固定大部分从污染土壤迁移到距污染土壤1毫米范围内根际土壤中的铅。有羟基磷灰石的根际土壤中主要的铅形态是残渣态。因此，植物生长没有受到抑制，植物地上部分的铅浓度保持在背景水平。这些结果表明，根际土壤中5%（重量）的羟基磷灰石可能会固定大部分迁移到距污染土壤1毫米范围内根际土壤中的铅，从而防止铅向根表面迁移。
