『Abstract
Ion concentrations in relatively low-intensity precipitation
were measured in southern Indiana, USA and are presented as a
function of their temporal evolution during individual precipitation
events with a specific focus on the first 30 min of those events.
These data indicate that during individual rain events potassium
concentrations in precipitation may decline by up to 70％-80％ in
the first 30 min of the event. The other ions exhibited less rapid
concentration declines during this event which are in rank order
(highest to lowest); sodium, chloride, magnesium, nitrate, calcium,
sulfate and ammonium. There is some evidence that the initial
declines for precipitation accumulations up to 2 mm in the concentration
of chloride, calcium and sulfate in precipitation more closely
approximate a power-law dependency on precipitation depth than
the commonly applied exponential form which, if confirmed, may
have implications for efforts to correct flux networks for under-sampling
due to delay in sample collection. Scavenging coefficients (b)
derived using an exponential relationship over entire events for
sodium, chloride, nitrate, calcium, sulfate and ammonium indicate
highest values for sodium and lowest for ammonium, but the uncertainty
bounds on ion-specific values of b are sufficiently large
that they are statistically indistinguishable.
Keywords: ion concentration; precipitation scavenging; scavenging
efficiencies; sequential sampling; wet deposition』
1. Introduction
2. Methodology
2.1. Sample collection
2.2. Sample analysis
3. Results
4. Concluding remarks
Acknowledgments
References