All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 142 22 5
PDF Downloads 23 16 1

Observations of Aerosols over Southern California Coastal Waters

G. M. HidyRockwell International Science Center, Thousand Oaks, Calif.
California Institute of Technology, Pasadena, Calif.

Search for other papers by G. M. Hidy in
Current site
Google Scholar
PubMed
Close
,
P. K. MuellerEnvironmental Protection Regency, Region IX.

Search for other papers by P. K. Mueller in
Current site
Google Scholar
PubMed
Close
,
H. H. WangRockwell International Science Center, Thousand Oaks, Calif.

Search for other papers by H. H. Wang in
Current site
Google Scholar
PubMed
Close
,
J. KarneyU. S. Naval Missile Center, Pt. Mugu, Calif.

Search for other papers by J. Karney in
Current site
Google Scholar
PubMed
Close
,
S. TwissAir & Industrial Hygiene Laboratory, California State Department of Public Health, Berkeley

Search for other papers by S. Twiss in
Current site
Google Scholar
PubMed
Close
,
M. ImadaAir & Industrial Hygiene Laboratory, California State Department of Public Health, Berkeley

Search for other papers by M. Imada in
Current site
Google Scholar
PubMed
Close
, and
A. AlcocerAir & Industrial Hygiene Laboratory, California State Department of Public Health, Berkeley

Search for other papers by A. Alcocer in
Current site
Google Scholar
PubMed
Close
Restricted access

Abstract

To characterize the background aerosol in air off the California coast, observations of suspended particles were made in the summer and fall of 1970 on San Nicolas Island (SNI), located about 130 km west-south-west of Los Angeles. Measurements of the physical and chemical properties of aerosols showed that the particles are a complex mixture of material from marine and continental origins. The Aitken nuclei population averaged 2400 cm−3, while the particles >0.5 μm diameter averaged 20–100 cm−3. The average total mass concentration of aerosol evaluated from 22 samples was 29.8 μg m−3, but the refined fraction defined as particles ≲3.5 μm diameter was 40% of this level

The averages of the chemical analysis of 13 samples revealed that 11% of the aerosol sampled at a 200 m height above the ocean was sea salt, while approximately 20% evidently was soil dust, as indicated by silicates. Over 25% of the suspended material was found to be sulfate, nitrate or ammonium, which are constituents believed to be produced primarily from gaseous transformation reactions in the atmosphere.

More than 20% of the sampled material was volatile in nature and is believed to be partly water. The ratio for the average chlorine to sodium concentrations from the analysis of 13 different samples was 2.4 compared with 1.8 for sea water. This high ratio supports other limited results for unpolluted air from offshore sources taken in this geographical region. The anomaly is believed to be linked with chemical reactions transforming gaseous chlorine compounds into condensed material.

Comparison was made between the aerosol sampled on San Nicolas Island and the “natural” background contribution of the Los Angeles smog aerosol, as estimated elsewhere assuming contributions solely from sea salt and soil dust. The calculated background and the composition of the SNI aerosol were qualitatively similar, with the principal differences showing in Ca, Zn, SO4 and NO3. Further comparison with aerosol analyzed from.Pasadena illustrated the major contribution of localized pollution to the chemical properties of the particles, particularly in the concentrations of Mu, Ca, Br, Fe, Pb, SO4 and NO3.

Abstract

To characterize the background aerosol in air off the California coast, observations of suspended particles were made in the summer and fall of 1970 on San Nicolas Island (SNI), located about 130 km west-south-west of Los Angeles. Measurements of the physical and chemical properties of aerosols showed that the particles are a complex mixture of material from marine and continental origins. The Aitken nuclei population averaged 2400 cm−3, while the particles >0.5 μm diameter averaged 20–100 cm−3. The average total mass concentration of aerosol evaluated from 22 samples was 29.8 μg m−3, but the refined fraction defined as particles ≲3.5 μm diameter was 40% of this level

The averages of the chemical analysis of 13 samples revealed that 11% of the aerosol sampled at a 200 m height above the ocean was sea salt, while approximately 20% evidently was soil dust, as indicated by silicates. Over 25% of the suspended material was found to be sulfate, nitrate or ammonium, which are constituents believed to be produced primarily from gaseous transformation reactions in the atmosphere.

More than 20% of the sampled material was volatile in nature and is believed to be partly water. The ratio for the average chlorine to sodium concentrations from the analysis of 13 different samples was 2.4 compared with 1.8 for sea water. This high ratio supports other limited results for unpolluted air from offshore sources taken in this geographical region. The anomaly is believed to be linked with chemical reactions transforming gaseous chlorine compounds into condensed material.

Comparison was made between the aerosol sampled on San Nicolas Island and the “natural” background contribution of the Los Angeles smog aerosol, as estimated elsewhere assuming contributions solely from sea salt and soil dust. The calculated background and the composition of the SNI aerosol were qualitatively similar, with the principal differences showing in Ca, Zn, SO4 and NO3. Further comparison with aerosol analyzed from.Pasadena illustrated the major contribution of localized pollution to the chemical properties of the particles, particularly in the concentrations of Mu, Ca, Br, Fe, Pb, SO4 and NO3.

Save