![Concentration-dependent NH"3 deposition processes for mixed moorland semi-natural vegetation [An article from: Atmospheric Environment]](https://www.ebooknetworking.net/books/B00/0PD/bigB000PDTDM8.jpg)
Concentration-dependent NH"3 deposition processes for mixed moorland semi-natural vegetation [An article from: Atmospheric Environment]
Description
This digital document is a journal article from Atmospheric Environment, published by Elsevier in 2007. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.
Description:
Dry deposition modelling typically assumes that canopy resistance (R"c) is independent of ammonia (NH"3) concentration. An innovative flux chamber system was used to provide accurate continuous measurements of NH"3 deposition to a moorland composed of a mixture of Calluna vulgaris (L.) Hull, Eriophorum vaginatum L. and Sphagnum spp. Ammonia was applied at a wide range of concentrations (1-100@mgm^-^3). The physical and environmental properties and the testing of the chamber are described, as well as results for the moorland vegetation using the 'canopy resistance' and 'canopy compensation point' interpretations of the data. Results for moorland plant species demonstrate that NH"3 concentration directly affects the rate of NH"3 deposition to the vegetation canopy, with R"c and cuticular resistance (R"w) increasing with increasing NH"3 concentrations. Differences in R"c were found between night and day: during the night R"c increases from 17sm^-^1 at 10@mgm^-^3 to 95sm^-^1 at 80@mgm^-^3, whereas during the day R"c increases from 17s m^-^1 at 10 @mg m^-^3 to 48s m^-^1 at 80 @mg m^-^3. The lower resistance during the day is caused by the stomata being open and available as a deposition route to the plant. R"w increased with increasing NH"3 concentrations and was not significantly different between day and night (at 80@mgm^-^3 NH"3 day R"w=88sm^-^1 and night R"w=95sm^-^1). The results demonstrate that assessments using fixed R"c will over-estimate NH"3 deposition at high concentrations (over ~15@mgm^-^3).
Description:
Dry deposition modelling typically assumes that canopy resistance (R"c) is independent of ammonia (NH"3) concentration. An innovative flux chamber system was used to provide accurate continuous measurements of NH"3 deposition to a moorland composed of a mixture of Calluna vulgaris (L.) Hull, Eriophorum vaginatum L. and Sphagnum spp. Ammonia was applied at a wide range of concentrations (1-100@mgm^-^3). The physical and environmental properties and the testing of the chamber are described, as well as results for the moorland vegetation using the 'canopy resistance' and 'canopy compensation point' interpretations of the data. Results for moorland plant species demonstrate that NH"3 concentration directly affects the rate of NH"3 deposition to the vegetation canopy, with R"c and cuticular resistance (R"w) increasing with increasing NH"3 concentrations. Differences in R"c were found between night and day: during the night R"c increases from 17sm^-^1 at 10@mgm^-^3 to 95sm^-^1 at 80@mgm^-^3, whereas during the day R"c increases from 17s m^-^1 at 10 @mg m^-^3 to 48s m^-^1 at 80 @mg m^-^3. The lower resistance during the day is caused by the stomata being open and available as a deposition route to the plant. R"w increased with increasing NH"3 concentrations and was not significantly different between day and night (at 80@mgm^-^3 NH"3 day R"w=88sm^-^1 and night R"w=95sm^-^1). The results demonstrate that assessments using fixed R"c will over-estimate NH"3 deposition at high concentrations (over ~15@mgm^-^3).
