Domínguez María T, Madrid Fernando, Marañón Teodoro, Murillo José M
Instituto de Recursos Naturales y Agrobiologia de Sevilla, CSIC, P.O. Box 1052, 41080 Seville, Spain.
Chemosphere. 2009 Jul;76(4):480-6. doi: 10.1016/j.chemosphere.2009.03.026. Epub 2009 Apr 17.
Afforestation of contaminated land by trees is considered as a feasible strategy for the extensive stabilization of contaminants. In this work, we studied the patterns of metal availability (Cd, Cu, Pb and Zn) in a contaminated and afforested area. Specifically, we observed the response of Holm oak (Quercus ilex subsp. ballota) leaves to changes in the availability of metals under field conditions, focusing on Cd. Under controlled conditions we studied the performance of oak seedlings exposed to high levels of Cd, with the aim of analyzing the patterns of translocation and tolerance of the seedlings. Cadmium was the most available metal, in relative terms; 15% of the total Cd in the soil was extracted with NH4NO3. The availabilities of Cd, Cu and Zn showed exponential relationships with soil pH (pH values ranged from 2.4 to 8.4). Cadmium accumulation in the leaves was not related to the changes in Cd availability. Greenhouse studies showed that seedlings had a high Cd retention capacity in fine roots (up to 7 gkg(-1)) and low rates of Cd translocation to the leaves (transfer coefficients below 0.03). Root biomass and thickness was altered by exposure to Cd. In spite of this, the chlorophyll fluorescence measurements (an indicator of plant stress) only differed slightly from the control treatment at a Cd dose of 200 mgL(-1). Due to the relatively high tolerance to Cd and the capacity of roots to retain this metal, Holm oak may be useful for the phytostabilization of soils contaminated by Cd.
通过树木对污染土地进行绿化被认为是广泛稳定污染物的一种可行策略。在这项工作中，我们研究了一个受污染且已绿化区域中金属（镉、铜、铅和锌）的有效性模式。具体而言，我们观察了地中海栓皮栎（Quercus ilex subsp. ballota）叶片在田间条件下对金属有效性变化的响应，重点关注镉。在可控条件下，我们研究了暴露于高浓度镉的栎树苗的生长情况，旨在分析树苗的转运和耐受模式。相对而言，镉是最易获取的金属；土壤中总镉的15%可被硝酸铵提取。镉、铜和锌的有效性与土壤pH值呈指数关系（pH值范围为2.4至8.4）。叶片中的镉积累与镉有效性的变化无关。温室研究表明，树苗在细根中具有较高的镉保留能力（高达7 gkg(-1)），且镉向叶片的转运速率较低（转运系数低于0.03）。根系生物量和厚度因镉暴露而改变。尽管如此，叶绿素荧光测量（植物胁迫的指标）在镉剂量为200 mgL(-1)时与对照处理仅略有不同。由于对镉具有相对较高的耐受性以及根系保留这种金属的能力，地中海栓皮栎可能有助于对镉污染土壤进行植物稳定修复。
