Transpiration stream concentration factor

Estimating the Transpiration Stream Concentration Factor (TSCF) and Root Concentration Factor (RCF) for Some Typical Contaminants (8)... 

TSCF Transpiration stream concentration factor (dimensionless) u Air velocity (m/s)... 

Root uptake has been proven to be an important pathway for contaminants with intermediate octanol-water partitioning coefficients (Aiow)- Variable uptake of an organic compound by different plants has been observed. Plant species such as Daucus carota (carrot) and Pastinaca sativa (parsnip) with swollen storage roots did not translocate chemicals as well as expected from barley experiments. While the lipid content was considered a factor, plant structure, root types, and other properties may all play a role. The effect of the chemical itself was best illustrated by the increasing root concentration factor (RCF) and the bell-shaped transpiration stream concentration factors (TSCF) relative to logAiow- The physiochemical properties of compounds, including the Ko, solubility, and... 

HMX uptake was evaluated from 21-d hydroponic exposures using hybrid poplar trees (Populus deltoids x nigra) at concentrations of 4.70, 2.84, and 1.37 mg L 1 [80], After 21 d, 44.83% of the HMX in solution was sequestered by the trees. No toxic effects were evident at any of the exposures. The authors also calculated a transpirational stream concentration factor of 0.18 0.03 suggesting that HMX was moderately available for uptake by plant roots. Root concentration factors were also calculated at 5.55 1.78 [80], As with other studies, most HMX was... 

TABLE 5.4 Root Concentration Factors and Transpiration Stream Concentration Factors for Phenyl Ureas in Barley Seedlings... 

The efficiency with which a compound moves into the shoot is defined by the transpiration stream concentration factor, TSCF... 

Figure 8, Calculated transpiration stream concentration factor for soybeans for soil with 0% organic material (hydroponic), 1% organic material, and 5%...

However, at the endodermis, which is the cylindrical sheath of cells that surround the vascular tissues, the apoplastic pathway is blocked by the Casparian strip. If compounds are to enter the stele and reach the xylem vessels, they must pass through the plasmalemma membrane of the endo-dermal cells and so enter the symplasm. The transpiration stream concentration factor (TSCF) describes the efficiency of this process for compounds relative to that for water " ... 

Figure 9.5. Relationship between the translocation of chemicals to shoots following uptake by roots (expressed as the transpiration stream concentration factor) and the octan-l-ol/water partition coefficients (as log K y,) (a) in barley O, O-methylcarbamoyloximes x, substituted phenylureas (b) literature values for several herbicides and fungicides in different plant species. (Reproduced from Ref. 34.)...

The relative tendency of a chemical to move from root to shoot (above ground tissue) tissue is often described by the transpiration stream concentration factor (TSCF), the ratio of the chemical s concentration in the xylem sap to that in the solution to which the plant root is exposed. 

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