@article {10.3844/ajabssp.2009.24.31,
article_type = {journal},
title = {Hard Coal Fly Ash and Silica-Effect of Fine Particulate Matter Deposits on Brassica chinensis},
author = {Ulrichs, Christian and Schmidt, Uwe and Mucha-Pelzer, Tanja and Goswami, Arunava and Mewis, Inga},
volume = {4},
year = {2009},
month = {Mar},
pages = {24-31},
doi = {10.3844/ajabssp.2009.24.31},
url = {https://thescipub.com/abstract/ajabssp.2009.24.31},
abstract = {Problem statement: One focus in recent atmospheric pollution 
research is on fine Particle Matter (PM), especially as result of increasing traffic 
and anthropogenic activity in urban areas. Here, the impact on animal and human 
health has been in the center of many studies. Despite the fact that PM depositions 
can affect plants on the long term, there are only few studies about the impact 
on plants conducted. Approach: Therefore we studied the impact 
of PM on plants, using naturally occurring silica dusts (diatomaceous earth) and 
hard Coal Fly Ash (CFA) from burning processes. Dusts were applied onto Brassica 
chinensis L. using a simple duster (covering upper leaf surfaces) or electrostatically 
(covering leaf upper and -underside). Results: Main components 
of the tested CFA are SO42-, K, Ca and NH4+. The pH value of eluates was found 
to be around 9.5 in CFA and 5.7 in silica. B. chinensis was insensitive towards 
the high pH and showed no growth reduction when grown in silica or CFA substrate. 
PM deposition on leaf surfaces results through shading in a reduced photosynthetic 
activity. The reduction is relatively higher at higher light intensities. Photosynthesis 
stays reduced after removal of silica PM from leaf surfaces. We assume that stomata 
get cloaked by small particles and that silica absorbs lipids from the epicuticle 
resulting in a general stress reaction. Smaller sized silica particles resulted 
in a higher reduction of CO2-absorption. Next to particle size is the photosynthesis 
negatively correlated with exposure time for silica PM. The chlorophyll fluorescence 
data indicate that dust-covered leaves exhibited significantly lower quantum yield 
of PS II and a reduced quantum efficiency of PS II and therefore supported the 
gas exchange data. Conclusion: Reduced photosynthetic performance 
would be expected to reduce growth and productivity of B. chinensis. In contrast 
to silica hard coal fly ash showed only a reduction of photosynthesis through 
shading but did not have any long time effects after washing them off.},
journal = {American Journal of Agricultural and Biological Sciences},
publisher = {Science Publications}
}