Aerosol annual atmospheric

Atmospheric transport of atrazine-contaminated aerosol particulates, dusts, and soils may contribute significantly to atrazine burdens of terrestrial and aquatic ecosystems. The annual atmospheric input of atrazine in rainfall to the Rhode River, Maryland, as one example, was estimated at 1016 mg/surface ha in 1977, and 97 mg/ha in 1978 (Wu 1981). A similar situation exists with fog water. When fog forms, exposed plant surfaces become saturated with liquid for the duration of the fog (Glotfelty et al. 1987). 

It is our estimate that all pollutant sources result in about 300 X 10 tons per year of particulate material being introduced into the atmosphere and that pollutant and natural sources combined amount to about 3000 X 10 tons per year. Thus, on a global scale 30 X 10 tons per year of pollutant photochemical aerosols are about 10% of the total pollutant aerosols and about 1% of the total annual atmospheric aerosol production. The 200 X 10 tons of aerosol particles resulting from the photochemical scavenging reactions involving natural organic emissions is somewhat less than 10% of the total aerosols emitted to the global atmosphere. 

The major ions have two main escape routes from the ocean (1) incorporation into sediments or pore water and (2) ejection into the atmosphere as seasalt spray. This spray is caused by bursting bubbles that produce small particles, called aerosols, that range in diameter from 0.1 to 1000 pm. The annual production rate of seasalt aerosols is large, on the order of 5 x lO kg/y, but virtually all of it is quickly returned when the spray fells back onto the sea surfece. A small fraction (about 1%) is deposited on the coastal portions of land masses and carried back into the ocean by river runoff. As shown in Table 21.6, seasalts represent a significant fraction of dissolved solids in river runoff, especially for sodium and chloride. Due to the short timescale of this process, seasalt aerosol losses and inputs are considered by geochemists to be a short circuit in the crustal-ocean-atmosphere fectory. The solutes transported by this process are collectively referred to as the cyclic salts. ... 

The chlorofluorocarbon compounds of methane and ethane are collectively known as freons. They are extremely stable, unreactlve, non-toxic, non-corrosive and easily liquefiable gases. Freon 12 (CCI2F2) Is one of the most common freons In Industrial use. It Is manufactured from tetrachloromethane by Swarts reaction. These are usually produced for aerosol propellants, refrigeration and air conditioning purposes. By 1974, total freon production In the world was about 2 billion pounds annually. Most freon, even that used In refrigeration, eventually makes Its way Into the atmosphere where It diffuses unchanged Into the stratosphere. In stratosphere, freon Is able to Initiate radical chain reactions that can upset the natural ozone balance (Unit 14, Class XI). 

Dod, R.L. Rosen, H. Novakov, T. "Optico-thermal analysis of the carbonaceous fraction of aerosol particles", in "Atmospheric Aerosol Research Annual Report 1977-78", Lawrence Berkeley Laboratory, Berkeley, California LBL-8696, pp.2 10. 

The atmospheric concentration of natural and bomb-produced radionuclides has been measured at ground level for several years at three locations throughout the world. The manner in which the concentration decreased suggested a half-residence time for stratospheric aerosols of 11.8 months at 46°N latitude. The annual spring concentration maximum occurred one to four months earlier at 71°N than at 46°N. Cosmogenic 7Be attained a maximum concentration before the bomb-produced radionuclides at 71° N and later than the bomb-produced isotopes at 46°N. The rate of increase toward the annual peak concentration for most radionuclides could be approximated by an exponential in which the concentration doubled every 60 days likewise, the rate of decrease from the maximum concentration could be approximated by an exponential with a half-time of about 40 days for most radionuclides except 7Be at 46°N, which shows a half-time of about 60 days. 

Several European intensive short-term ( campaign-type ) projects have provided important information on the atmospheric aerosol properties in Europe, usually by concentrating on specific aerosol properties or interactions. However, these kinds of campaign-type measurements do not necessarily represent the seasonal or annual variations of the aerosol concentrations and can overestimate some properties of the aerosol populations. Long-term measurements, especially with intercalibrated instruments and common data handling and calibration protocols make the data comparison between stations much more reliable and provide the end users (e.g., atmospheric modelers) good datasets to compare with. 

Table 1.10. Annual average values of the total content (mg m 2) in the atmosphere of different types of aerosol in the Northern and Southern Hemispheres and over the globe.

Since the World Ocean is the most inertial component of the global climate system, analyzing its variability is a top priority, especially as Levitus et al. (2001) detected annual increases in the heat content of the upper layer of all oceans over the last 45 years. With this in mind, Barnett et al. (2001) compared numerical modeling results of the heat content of the upper 3 km layer of various oceans with observational data. Calculations were made using the parallel climate model (PCM) for the atmosphere-ocean system without any flux adjustment. Calculations were made of five versions of the forecast growth in GHG concentration and sulfate aerosol content in the atmosphere. 

Systematic studies of the atmospheric aerosol in the Antarctic revealed a strong annual change in Mirny and at the South Pole, with summer-season values of aerosol concentrations exceeding tenfold those in winter, which points to a substantial effect of meteorological conditions on the values of Cgba. 

The biosphere is a major contributor to the atmosphere of heavier hydrocarbons. Fritz Went (8, 9), who first recognized the global extent of smog, pointed out the general importance of natural emissions from vegetation. He estimated that sources in the biosphere annually emit between 170 X 10 and 10 tons of hydrocarbon material to the atmosphere. Went also observed that these materials are mainly in the terpene class and that, because they are photochemically reactive, these materials are polymerized in atmospheric photochemical reactions to form an organic aerosol. He attributes the blue haze found in many forested areas to the optical effects of this aerosol. 

Methylene chloride is a widely used industrial chemical with reported atmospheric emissions of more than 126 million pounds annually in the United States. The principal route of exposure for the general population to methylene chloride is by inhalation. Occupational and consumer exposure to methylene chloride commonly occurs from spray painting and contact with consumer products such as paint strippers or aerosol cans, that contain methylene chloride. Exposures may occur as a result of breathing the vapors given off by the product or from direct dermal contact. Occupational exposure to methylene chloride by the inhalation route offers the most opportunity for exposure but it can also be absorbed through the skin. 

The total mass of particulate matter per unit volume of air is perhaps the simplest integral property, and it is on this quantity that U.S. federal standards for particulate pollution have been based. Until recently there was a single primary (health related) standard of 50 g/m (annual geometric mean) and 150 /rg/m- (maximum 24-hr concentration not to be exceeded more than once per year), with an upper cutoff in panicle size of 10 /ttm (PMio). However, epidemiological studies indicate an association between adverse health effects, including enhanced mortality, and submicron aerosol concentrations in many U.S. cities (Pope cl al.. 1995). This has led to the establishment of an additional mass ba.sed standard for particles smaller than 2.5 /im (PMj.j) (U.S. EPA, 1996). There is also a separate health-based standard for lead, one component of the atmospheric aerosol. 

Lacustrine Pertaining to development in lakes Mesic This term has a very broad meaning. In ecology, it refers to moderate conditions with respect to both temperature and moisture. In soil, specifically in soil taxonomy, mesic is used to represent a soil temperature (mean annual) that falls in the range 8-15° C Mole fraction The ratio of the moles of a substance to the total number of moles in the sample. In the atmosphere this is the same as the volume fraction Non-seasalt (nss) The amount of an element or compound in the bulk aerosol mass that is in excess of its seawater ratio with sodium or chloride. Often applied to sulfate Obligatory anaerobes Organisms restricted to life in anaerobic environments... 

The estimate for sea salt goes back to a detailed study of Eriksson (1959) of the geochemical cycles of chloride and sulfur. He calculated the rate of dry fallout of sea-salt particles from a vertical eddy diffusion model and then existing measurements of sea-salt concentrations over the ocean. This led to a global rate for dry deposition of 540 Tg/yr. Eriksson then argued that wet precipitation would remove a similar amount annually. It is now known, however, that wet precipitation is more effective than dry deposition in removing aerosol particles from the atmosphere, so that Eriksson s value must be an underestimate. The discussion in Section 10.3.5 suggests a flux rate for sea salt of about 5,000 Tg/yr. 

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