Ouyang Ying
Department of Water Resources, St. Johns River Water Management District, PO Box 1429, Palatka, Florida 32178-1429, USA.
J Contam Hydrol. 2008 Jan 7;95(1-2):17-29. doi: 10.1016/j.jconhyd.2007.07.010. Epub 2007 Aug 2.
Knowledge of mechanisms for uptake, translocation, and accumulation of soil contaminants in plants is essential to successful applications of the phytoremediation technique. Analysis and evaluation of these mechanisms would be greatly facilitated by the availability of a dynamic model that can predict soil contaminant uptake by roots, transport from roots through stems to leaves, and accumulation in plant during the transport process. In this study, a dynamic model for uptake and translocation of contaminants from a soil-plant ecosystem (UTCSP) was developed using the STELLA modeling tool. The structure of UTCSP consists of time-dependent simultaneous upward transport, accumulation, and transpiration of water and contaminants in the soil-plant-atmosphere continuum, which was driven by water potential gradients among soils, roots, stems, leaves, and atmosphere. The UTCSP model was calibrated using the experimental measurements and applied to predict phytoremediation of 1,4-dioxane from a sandy soil by a poplar tree. Simulation results showed that about 20% of 1,4-dioxane was removed from the soil by the poplar tree in 90 days. The simulations further revealed that while the mass of 1,4-dioxane in the poplar tree increased consecutively with time, the rates of water and 1,4-dioxane uptake and translocation in the roots, stems, and leaves have a typical diurnal distribution pattern: increasing during the day and decreasing during the night, resulting from daily variations of plant water potentials that were caused by leaf water transpiration. This study suggests that the UTCSP model is a useful tool for estimating phytoremediation of contaminants in the soil-plant ecosystems.
了解植物对土壤污染物的吸收、转运和积累机制对于植物修复技术的成功应用至关重要。如果有一个动态模型能够预测根系对土壤污染物的吸收、从根系经茎到叶的转运以及转运过程中在植物体内的积累，那么对这些机制的分析和评估将得到极大的促进。在本研究中，使用STELLA建模工具开发了一个土壤 - 植物生态系统中污染物吸收和转运的动态模型（UTCSP）。UTCSP的结构包括土壤 - 植物 - 大气连续体中水分和污染物随时间的同步向上运输、积累和蒸腾，这是由土壤、根系、茎、叶和大气之间的水势梯度驱动的。UTCSP模型通过实验测量进行了校准，并应用于预测杨树对沙质土壤中1,4 - 二氧六环的植物修复。模拟结果表明，在90天内，杨树从土壤中去除了约20%的1,4 - 二氧六环。模拟还进一步揭示，虽然杨树体内1,4 - 二氧六环的质量随时间连续增加，但根系、茎和叶中水分和1,4 - 二氧六环的吸收和转运速率具有典型的昼夜分布模式：白天增加，夜间减少，这是由叶片水分蒸腾引起的植物水势的每日变化所致。本研究表明，UTCSP模型是估算土壤 - 植物生态系统中污染物植物修复的有用工具。
