Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Current issues and uncertanties in the measurement and modelling of air-vegetation exchange and within-plant processing of POPs.
AU - Barber, Jonathan L.
AU - Thomas, Gareth O.
AU - Kerstiens, Gerhard
AU - Jones, Kevin C.
PY - 2004
Y1 - 2004
N2 - Air–vegetation exchange of POPs is an important process controlling the entry of POPs into terrestrial food chains, and may also have a significant effect on the global movement of these compounds. Many factors affect the air–vegetation transfer including: the physicochemical properties of the compounds of interest; environmental factors such as temperature, wind speed, humidity and light conditions; and plant characteristics such as functional type, leaf surface area, cuticular structure, and leaf longevity. The purpose of this review is to quantify the effects these differences might have on air/plant exchange of POPs, and to point out the major gaps in the knowledge of this subject that require further research. Uptake mechanisms are complicated, with the role of each factor in controlling partitioning, fate and behaviour process still not fully understood. Consequently, current models of air–vegetation exchange do not incorporate variability in these factors, with the exception of temperature. These models instead rely on using average values for a number of environmental factors (e.g. plant lipid content, surface area), ignoring the large variations in these values. The available models suggest that boundary layer conductance is of key importance in the uptake of POPs, although large uncertainties in the cuticular pathway prevents confirmation of this with any degree of certainty, and experimental data seems to show plant-side resistance to be important. Models are usually based on the assumption that POP uptake occurs through the lipophilic cuticle which covers aerial surfaces of plants. However, some authors have recently attached greater importance to the stomatal route of entry into the leaf for gas phase compounds. There is a need for greater mechanistic understanding of air–plant exchange and the ‘scaling’ of factors affecting it. The review also suggests a number of key variables that researchers should measure in their experiments to allow comparisons to be made between studies in order to improve our understanding of what causes any differences in measured data between sites.
AB - Air–vegetation exchange of POPs is an important process controlling the entry of POPs into terrestrial food chains, and may also have a significant effect on the global movement of these compounds. Many factors affect the air–vegetation transfer including: the physicochemical properties of the compounds of interest; environmental factors such as temperature, wind speed, humidity and light conditions; and plant characteristics such as functional type, leaf surface area, cuticular structure, and leaf longevity. The purpose of this review is to quantify the effects these differences might have on air/plant exchange of POPs, and to point out the major gaps in the knowledge of this subject that require further research. Uptake mechanisms are complicated, with the role of each factor in controlling partitioning, fate and behaviour process still not fully understood. Consequently, current models of air–vegetation exchange do not incorporate variability in these factors, with the exception of temperature. These models instead rely on using average values for a number of environmental factors (e.g. plant lipid content, surface area), ignoring the large variations in these values. The available models suggest that boundary layer conductance is of key importance in the uptake of POPs, although large uncertainties in the cuticular pathway prevents confirmation of this with any degree of certainty, and experimental data seems to show plant-side resistance to be important. Models are usually based on the assumption that POP uptake occurs through the lipophilic cuticle which covers aerial surfaces of plants. However, some authors have recently attached greater importance to the stomatal route of entry into the leaf for gas phase compounds. There is a need for greater mechanistic understanding of air–plant exchange and the ‘scaling’ of factors affecting it. The review also suggests a number of key variables that researchers should measure in their experiments to allow comparisons to be made between studies in order to improve our understanding of what causes any differences in measured data between sites.
KW - POPs
KW - air/plant exchange
KW - modelling
KW - leaf
KW - cuticle
KW - stomata
KW - food chain
KW - global cycling
KW - POLYCYCLIC AROMATIC-HYDROCARBONS
KW - SEMIVOLATILE ORGANIC-COMPOUNDS
KW - DIBENZO-P-DIOXINS
KW - LASER-SCANNING MICROSCOPY
KW - CUTICULAR WATER PERMEABILITY
KW - BOUNDARY-LAYER CONDUCTANCE
KW - FAGUS-SYLVATICA L
KW - WELSH RAY GRASS
KW - LEAF DRY-MATTER
KW - ABIES L KARST
U2 - 10.1016/j.envpol.2003.08.024
DO - 10.1016/j.envpol.2003.08.024
M3 - Journal article
VL - 128
SP - 99
EP - 138
JO - Environmental Pollution
JF - Environmental Pollution
SN - 0269-7491
IS - 1-2
ER -