Influence of the precipitation interval on wet atmospheric deposition

Abstract

Atmospheric deposition (AD) is the transfer of soluble ions found in the atmosphere to the earth's surface by sedimentation (dry deposition) or by their inclusion or solution in raindrops (wet deposition, WAD). In this way, AD links the atmosphere with terrestrial ecosystems, being a key part of biogeochemical cycles. Although numerous investigations have quantified WAD, little is known about the temporal deposition patterns and the factors that control them. The objective of this work was to determine the relationship between the number of days without precipitation (DWP) between two rain events and the WAD magnitude. For this, we worked with AD data of soluble ions (Ca2+, Mg2+, K+, Na+, NH4+, NO3−, Cl− and SO42−) obtained from the National Atmospheric Deposition Program of the United States. This network contains more than 250 collections and measurement sites of WAD that provide information of quantities, trends and geographic distribution of ions contained in rainwater. 198 sites were selected to cover the environmental variability of the US. In addition, each site had atmospheric deposition records between 1994 and 2018. A positive relationship between WAD and DWP was observed in the region analyzed, however the effect of DWP was low. The model proposed achieved to explain much of the variability in wet depositions and demonstrated that, the amount of precipitation of the event and variability between sites strongly influence on WAD. We found that there is a short time interval in which the increase in WAD due to increases in the number of days without rain is greater and occurs between 0 and 5 days.