A Partition-Limited Model for the Plant Uptake of Organic Contaminants from Soil and Water
详细信息 查看全文
- 作者：Cary T. Chiou ; Guangyao Sheng ; and Milton Manes
- 刊名：Environmental Science & Technology
- 出版年：2001
- 出版时间：April 1, 2001
- 年：2001
- 卷：35
- 期：7
- 页码：1437 - 1444
- 全文大小：73K
- 年卷期：v.35,no.7(April 1, 2001)
- ISSN：1520-5851
文摘
In dealing with the passive transport of organic contaminantsfrom soils to plants (including crops), a partition-limitedmodel is proposed in which (i) the maximum (equilibrium)concentration of a contaminant in any location in theplant is determined by partition equilibrium with itsconcentration in the soil interstitial water, which in turn isdetermined essentially by the concentration in the soilorganic matter (SOM) and (ii) the extent of approach topartition equilibrium, as measured by the ratio of thecontaminant concentrations in plant water and soil interstitialwater, 
pt (
1), depends on the transport rate of thecontaminant in soil water into the plant and the volume ofsoil water solution that is required for the plant contaminantlevel to reach equilibrium with the external soil-water phase.Through reasonable estimates of plant organic-watercompositions and of contaminant partition coefficients withvarious plant components, the model accounts forcalculated values of pt in several published crop-contamination studies, including near-equilibrium values(i.e., pt 
1) for relatively water-soluble contaminants andlower values for much less soluble contaminants; thedifferences are attributed to the much higher partitioncoefficients of the less soluble compounds between plantlipids and plant water, which necessitates much largervolumes of the plant water transport for achievingthe equilibrium capacities. The model analysis indicatesthat for plants with high water contents the plant-waterphase acts as the major reservoir for highly water-solublecontaminants. By contrast, the lipid in a plant, even atsmall amounts, is usually the major reservoir for highly water-insoluble contaminants.
pt ( 1), depends on the transport rate of thecontaminant in soil water into the plant and the volume ofsoil water solution that is required for the plant contaminantlevel to reach equilibrium with the external soil-water phase.Through reasonable estimates of plant organic-watercompositions and of contaminant partition coefficients withvarious plant components, the model accounts forcalculated values of pt in several published crop-contamination studies, including near-equilibrium values(i.e., pt 1) for relatively water-soluble contaminants andlower values for much less soluble contaminants; thedifferences are attributed to the much higher partitioncoefficients of the less soluble compounds between plantlipids and plant water, which necessitates much largervolumes of the plant water transport for achievingthe equilibrium capacities. The model analysis indicatesthat for plants with high water contents the plant-waterphase acts as the major reservoir for highly water-solublecontaminants. By contrast, the lipid in a plant, even atsmall amounts, is usually the major reservoir for highly water-insoluble contaminants.