Aerosol particle samples collected from Asia and the North Pacific were analyzed to investigate the relationships among atmospheric sea salt, mineral aerosol, biogenic emissions (methanesulfonate (MSA)), and several anthropogenic substances (sulfate, nitrate, and various trace elements). These studies specifically focused on the sources for aerosol SO• and on the long-range transport of continental materials to the North Pacific. Ground-based aerosol sampling was conducted at four coastal-continental sites: Hong Kong, Taiwan, Okinawa, and Cheju; and at three remote Pacific islands, Shemya, Midway, and Oahu. Non-sea-salt (riss) SO• and MSA were uncorrelated at the East Asian sites presumably because pollution sources overwhelm the biogenic emissions of nss SO•. At the coastal-continental sites, marine biogenic emissions accounted for only 10 to <5% of the total nss SOj. In contrast, over the ocean the concentrations of riss SO2 and MSA were correlated (Midway r -0.70; Oahu r = 0.59), and higher percentages of biogenic riss SO• occurred, 55 and 70% at Oahu and Midway, respectively. The concentrations of riss SO• and NO•-were correlated at Cheju, Hong Kong, Taiwan, Okinawa, Midway, and Oahu, indicating some similarities in their sources and the processes governing their transport; however, differences in the riss SO•/NO•-ratios among sites suggest regional differences in the pollution component of the aerosol. At Shemya the concentrations of MSA during the summer (100 ng m -3 or more) are about 2 orders of magnitude higher than those in winter. The dimethylsulfide-derived fraction of the riss SO2 is highest in the summer when the monthly median riss SO2/MSA ratios range from 2.7 to 4.5, i.e., comparable to the ratios observed over Antarctica and other high-latitude locations. However, the monthly median riss SO•/MSA ratios increase, reaching 50 to 200 in the winter as productivity nearly ceases, and the biogenic fraction of nss SO• at Shemya decreases dramatically; this suggests a strong seasonal pollution component to the sulfate aerosol. The meteorological conditions favoring the long-range transport of Asian dust to the North Pacific also lead to transport of anthropogenic materials. At Oahu the correlation between NO• and A1 (dust) was highly significant (r = 0.75; p < 0.001), while the correlations between nitrate and A1 at the continental sites were low. These differences indicate that the composition of the air sampled at the coastalcontinental stations may be quite different from the air transported to the remote ocean. This phenomenon also appeared to affect the relationship between riss SO• and antimony. The correlations between riss SO• and Sb were weak at the Asian sites but strong at the open ocean sites where the riss SO•/Sb ratios were higher than those over the continent. Introduction The rapid industrial development in Asia is responsible for the high and increasing concentrations of a variety of air pollutants in the region. While the atmosphere over the remote North Pacific Ocean is thought to be ...
The concentrations of trace elements in aerosol particles from the atmosphere over the North Atlantic Ocean were determined as part of a program designed to characterize the chemical climatology of the region. For these studies, which were part of the Atmosphere‐Ocean Chemistry Experiment (AEROCE), 2 years of samples were collected at Tudor Hill, Bermuda (BTT), and at Ragged Point, Barbados (BAT); and 1 year of samples was collected at Mace Head, Ireland (MHT) and at the Izaña Observatory, Tenerife, Canary Islands (IZT). One major component of the aerosol was atmospheric dust, and the ranking for the median mineral dust concentrations as represented by aluminum was BAT > IZT > BTT > MHT. The Al concentrations at BAT, IZT, and BTT ranged over 4 orders of magnitude, i.e., from 0.001 to 10 μg m−3. At MHT the maximum dust concentrations were about a factor of 10 lower than at the other sites, but the lower end of the range in dust concentrations was similar at all sites. The mineral dust concentrations generally were highest in summer, and the flux of atmospheric dust was dominated by sources in North Africa. The elements showing clear enrichments over the concentrations expected from sea salt or crustal sources were I, Sb, Se, V, and Zn. At Izaña, which is in the free troposphere (elevation ∼2360 m), the concentrations of Se and I were much lower than at the boundary layer sites; this difference between sites most likely results from the marine emissions of these elements. The impact of pollution sources on trace element concentrations was evident at all sites but varied with season and location. The concentrations of elements originating from pollution sources generally were low at Barbados. Analyses of trace element ratios indicate that there are large‐scale differences in the pollution emissions from North America versus those from Europe and Africa. Emissions from pyrometallurgical industries, steel and iron manufacturing, and possibly biomass burning are more evident in the atmospheric samples influenced by transport from Europe and Africa.
Environmental concerns in aquatic environments have increased and require new and cost-effective real-time monitoring systems. Furthermore the Water Framework Directive (WFD) across the European Union (EU) and the growing international emphasis on the management of water quality and its sustainability are giving rise to a market for intelligent underwater monitoring systems. The aim of this paper is to study the feasibility of using electromagnetic (EM) waves in an underwater communication system and to develop a Wireless Sensor Network (WSN) using cheap commodity motes in the unlicensed (ISM) frequency bands for applications including environmental monitoring.
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