Atmospheric dry deposition to leaf surfaces at a rural site of India

Dry deposition flux of major ions (Na+, K+, Ca2+, Mg2+, NH4+, F−, Cl−, NO3− and SO42−) to natural surfaces [guava (Psidium guyava) and peepal (Ficus religiosa) leaves] are determined at Rampur, a rural site of semi-arid region of India. Dry deposition flux is the highest for Ca2+ on guava leaves and for NH4+ on peepal leaves. Overall dry deposition flux is higher on guava leaves than of peepal leaves. The variation in deposition flux may be due to surface characteristics (surface roughness) and arrangement of leaves. Peepal leaves are arranged along the axis of the stem, whereas guava leaves are at right angles to the stem. The deposition flux of cations contributes 66% and 76% of dry deposition of all major ions on guava and peepal leaves, respectively as soil is major contributor towards dry deposition flux in tropical regions. ANOVA revealed no significant seasonal difference in deposition, although there is a trend for higher in winter. Deposition velocities of NH4+, NO3− and SO42− are greater on guava leaves than peepal leaves, which can be attributed to the rougher surface of the guava leaf. Importance of this Paper: Dry deposition of atmospheric particle plays significant role in transfer of pollutants from the atmosphere to the earth surface. Vegetation is an important sink as it provides larger surface area. No such study on dry deposition of major ions (F−, Cl−, NO3−, SO42−, Na+, K+, Ca2+, Mg2+ and NH4+) on natural surfaces has been reported from this region. This study will help in understanding the processes of dry deposition and it will provide a data set, which will be helpful in making atmospheric budget, deriving critical loads and in development of model.