Greenhouse atmosphere

Endosulfan is a popular pesticide with greenhouse chrysanthemum producers. Surveys of usage patterns and potential exposure were conducted in Ontario (Archibald et al. 1994b). Collection and analysis of a-and P-endosulfan and endosulfan sulfate in greenhouse air have been described (Vidal et al. 1997). Results indicate that 7.5% of the initial concentration of endosulfan remained in the greenhouse atmosphere 24 hours after application. 

Kasting J. F. (1988) Runaway and moist greenhouse atmospheres and the evolution of Earth and Venus. Icarus 74, 472-494. 

Hemphill, D.D. "Concentrations of Selected Agricultural Chemicals In the Greenhouse Atmosphere" NCRPIAP Project //105 (48-NC-MO-O), FY-1980. University of Missouri. Unpublished Final Research Report submitted to the NCRPIAP Regional Office, Columbus, Ohio and to USDA-CSRS-S E. 

Chlorofluorocarbons (CFCs). Prior to 1978 most aerosol products contained chlorofluorocarbon propeUants. Since that time, the use of chlorinated fluorocarbons for aerosols has been seriously curtailed. These compounds have been impHcated in the depeletion of the ozone (qv) layer and are considered to be greenhouse gases (see Airpollution Atmospheric modeling). 

Gas CAS Registry Number 1990 Concentrations Concentration increases, %/yr Greenhouse efficiency Atmospheric residence times, c yrs... 

Properties. The ideal substitute should have identical or better performance properties than the CFG it replaces. The ideal CFG substitute must not harm the o2one layer, and must have a short atmospheric lifetime to ensure a low greenhouse warming potential (GWP). It also must be nontoxic, nonflammable, thermally and chemically stable under normal use conditions, and manufacturable at a reasonable pnce. The chemical industry has found substitutes that match many but not all of these cntena. 

Atmospheric Toxicity. The only known atmospheric toxicity effect of phthalates is the phytotoxicity arising from the use of DBP plasticized glazing bars in greenhouses. However, the higher phthalates such as DEHP are not phytotoxic. General atmospheric concentrations of phthalates are extremely low and it is concluded that they pose no risk to plants or animals. 

Carbon. Most of the Earth s supply of carbon is stored in carbonate rocks in the Hthosphere. Normally the circulation rate for Hthospheric carbon is slow compared with that of carbon between the atmosphere and biosphere. The carbon cycle has received much attention in recent years as a result of research into the possible relation between increased atmospheric carbon dioxide concentration, most of which is produced by combustion of fossil fuel, and the "greenhouse effect," or global warming. Extensive research has been done on the rate at which carbon dioxide might be converted to cellulose and other photosyntheticaHy produced organic compounds by various forms of natural and cultivated plants. Estimates also have been made of the rate at which carbon dioxide is released to soil under optimum conditions by various kinds of plant cover, such as temperature-zone deciduous forests, cultivated farm crops, prairie grassland, and desert vegetation. 

The addition of small amounts of carbon dioxide to the atmosphere in greenhouses greatly improves the growth rate of vegetables and flowers. 

Issues related to gases such as CO2, which contribute to the global greenhouse effect, are also rising in importance (see Atmospheric models). 

Carbon dioxide is a major greenhouse gas within the atmosphere. Water vapour is a greater contributor to the natural greenhouse effect (55-70% of the total radiative absorption compared to COj s 25%). However, the large inherent variability in atmospheric water vapour compared to the anthropogenically... 

A product of the second pathway, NjO, is a significant greenhouse gas. About a quarter of the annual input of NjO to the atmosphere comes from the ocean. 

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