TY - JOUR
T1 - The chemistry of intercepted clouds in Northern Arizona during the North American monsoon season
AU - Hutchings, James W.
AU - Robinson, Marin S.
AU - McIlwraith, Heide
AU - Triplett Kingston, Jennifer
AU - Herckes, Pierre
N1 - Funding Information:
Acknowledgments We are grateful to James Jones, Olivier Delhomme and Minae Tanaka for assistance with sample collection and Panjai Prapaipong for metal analysis. We are also grateful to Sheila Sandusky of the National Forest Service for providing access to the sampling site. The authors gratefully acknowledge the NOAA Air Resources Laboratory (ARL) for the provision of the HYSPLIT transport and dispersion model and/or READY website (http://www.arl.noaa.gov/ready.html) used in this publication. Partial funding for this work was provided by the National Science Foundation grant (ATM0530718)
PY - 2009/5
Y1 - 2009/5
N2 - Cloudwater samples have been collected for the first time at a high-elevation site in the US interior Southwest. Cloud samples were collected at the summit of Mt. Elden near Flagstaff, Arizona. The samples were analyzed for pH, ionic composition, trace metals, organic carbon content, and volatile organic compounds. All of the samples showed high pH values (5.12-6.66), which appear to be the result of soil/crustal acid-neutralizing components. Ammonium and nitrate were the dominant ionic species. Organic carbon concentrations ranged from 3 to 18 mg/l. Volatile aromatic compounds (toluene, ethylbenzene, and xylenes) were detected, although they did not contribute significantly to the dissolved organic matter (<1% of dissolved organic carbon). Still, their aqueous-phase concentrations were substantially higher than equilibrium partitioning from the gas phase would suggest. Metal concentrations were high when compared to other cloud studies in remote areas. Overall, with the exception of pH, the cloud chemistry showed marked inter-event variability. The source of the variability was investigated using NOAA HYSPLIT dispersion calculations. Like the cloud composition, the air mass back trajectories differed widely from event to event, and consistently, air masses that passed over highly urbanized areas had higher trace metal, organic, and ion concentrations than more pristine air masses.
AB - Cloudwater samples have been collected for the first time at a high-elevation site in the US interior Southwest. Cloud samples were collected at the summit of Mt. Elden near Flagstaff, Arizona. The samples were analyzed for pH, ionic composition, trace metals, organic carbon content, and volatile organic compounds. All of the samples showed high pH values (5.12-6.66), which appear to be the result of soil/crustal acid-neutralizing components. Ammonium and nitrate were the dominant ionic species. Organic carbon concentrations ranged from 3 to 18 mg/l. Volatile aromatic compounds (toluene, ethylbenzene, and xylenes) were detected, although they did not contribute significantly to the dissolved organic matter (<1% of dissolved organic carbon). Still, their aqueous-phase concentrations were substantially higher than equilibrium partitioning from the gas phase would suggest. Metal concentrations were high when compared to other cloud studies in remote areas. Overall, with the exception of pH, the cloud chemistry showed marked inter-event variability. The source of the variability was investigated using NOAA HYSPLIT dispersion calculations. Like the cloud composition, the air mass back trajectories differed widely from event to event, and consistently, air masses that passed over highly urbanized areas had higher trace metal, organic, and ion concentrations than more pristine air masses.
KW - Acid rain
KW - Cloud
KW - Cloud chemistry
KW - Secondary organic aerosol formation
KW - Volatile organic compounds
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U2 - 10.1007/s11270-008-9871-0
DO - 10.1007/s11270-008-9871-0
M3 - Article
AN - SCOPUS:65849266187
SN - 0049-6979
VL - 199
SP - 191
EP - 202
JO - Water, Air, and Soil Pollution
JF - Water, Air, and Soil Pollution
IS - 1-4
ER -