A method for evaluation of acidic sulfate and nitrate in precipitation

Abstract

A simple method is presented and used to estimate the portions of SO 2 -and NO3-that contribute to the strong acidity in weekly precipitation samples collected at three NADP sites in the eastern United States. The method assumes that, in general, the difference between SO ] -and NH 2 represents acidic sulfate and the difference between NO3-and soil-derived materials (the sum of Ca 2 +, Mg 2 +, and K ÷ ) represents acidic nitrate. Acidic sulfate and nitrate are considered to be the predominant source of H + (determined from laboratory pH) in the weekly precipitation samples. Most of the acidity for all three sites was attributed to acidic sulfate. The highest fraction of acidic SO 2-to H + wet deposition values was for the east-central Tennessee site (0.95) and the northeastern Illinois site (0.90), and the lowest fraction occurred at the central Pennsylvania site (0.75). The Tennessee site had the greatest acidic fraction of sulfate (0.84) and the Pennsylvania site had the greatest acidic fraction of nitrate (0.59).

Chemical characterization of ambient aerosol collected during the northeast monsoon season over the Arabian Sea: Anions and cations

“…This observation is in agreement with those made by other investigators [Berresheim et al, 1991;Huebert et al, 1996;Johansen et al, 2000;Naik et al, 1991;Savoie and Prospero, 1982;Sievering et al, 1990]. The reason is that in temperate regions and in the presence of H 2 SO 4 [Bassett and Seinfeld, 1984;Sisterson, 1989], HNO 3 evaporates from small particles and is subsequently deposited on large particles, which may be marine-or soil-derived. The PC analysis supports this phenomenon by demonstrating that NO 3 À in the coarse fraction correlates with the anthropogenic component.…”

Chemical composition of aerosols collected over the tropical North Atlantic Ocean

“…These values are in close agreement with observations by other investigators [Berresheim et al, 1991; Davison et al, 1996; Ellis et al, 1993; Galloway et al, 1993; Harrison et al, 1996; Huebert et al, 1996; Li-Jones and Prospero, 1998; Savoie et al, 1989b] carried out in the same region, where the low concentration corresponds to a clean marine atmospheric situation and the high concentration is typical for a somewhat polluted air mass.Slightly more than half of the total NO•-(53%) is typically associated with the coarse particle fraction. This is in agreement with observations made by a series of investigators [Bassett andSeinfeld, 1984;Berresheim et al, 1991;Huebert et al, 1996;Savoie and Prospero, 1982;Sievering et al, 1990;Sisterson, 1989] that demonstrated that most NO•-is found in the supermicron mode associated with Na + and CI-, while most of the NSS-SO42-is contained in the submicron mode. This is in strong contrast with the behavior of other anthropogenic tracers; their content is considerably higher in the fine than in the coarse fraction' almost 3 times as much NSS-SO42-is present in the fine fraction, while the corresponding value of Zn is 2.6 and for Pb 2.5.…”

Rainfall chemistry: long range transport versus below cloud scavenging. A two-year study at an inland station (Opme, France)

“…The three factors explain 99.7% of the total variance of all the data ( (Sisterson, 1989;Hov and Hjollo, 1994). The second factor (35.6% of the total variance) highlights the association of Na + , Cland Mg 2+ and then corresponds to the marine origin.…”