Agriculture ozone depletion

Ozone depletion has a number of consequences for human health and agriculture. These include increased rates of skin cancer and eye cataracts, weakening of immune systems, damage to crops, reductions in primary producers (plankton) in the ocean and increasing air pollution. 

Midpoint indicatois Climate change. Ozone depletion. Photochemical oxidant formation. Particulate matter formation. Ionising radiation. Terrestrial acidification. Human toxicity. Terrestrial ecotoxicity. Freshwater ecotoxicity. Marine ecotoxicity. Metal depletion. Fossil depletion. Water depletion. Freshwater eutrophication. Marine eutrophication. Agricultural land occupation. Urban land occupation and Natural land transformation. Endpoint indicators Human health. Ecosystem diversity and Resource availability. 

Resource availability Ecosystem diversity Human health Natural land transformation Urban land occupation Agricultural land occupation Marine eutrophication Freshwater eutrophication Water depletion Fossil depletion Metal depletion Marine ecotoxicity Freshwater ecotoxicity Terrestrial ecotoxicity Human toxicity Terrestrial acidification Ionising radiation Particulate matter formation Photochemical oxidant formation Ozone depletion Climate change L -10%... 

Although useful in agriculture as a soil fumigant, methyl bromide is an ozone-depleting chemical, and its production is being phased out. The industrial preparation of methyl bromide is from methanol, by reaction with hydrogen bromide. Write a mechanism for this reaction and classify it as S l or 8 2. 

The comparative environmental impacts of PLA and PE, PS, PP, and PET for other environmental impact categories can be estimated by applying an LCIA tool to the PLA data contained within the ecoinvent database. TRACI (Tool for the Reduction and Assessment of Chemical and Other Environmental Impacts), developed by the U.S. EPA, was used to calculate the environmental impacts related to eutrophication, ecotoxicity, acidification, ozone depletion, smog formation, and human health (Figure 26.6) [53]. The impacts for PLA from the ecoinvent database (PLArSP) and the modified agricultural stage (PLA SP + L) are calculated in the same manner as previously discussed. 

Reduction in stratospheric ozone and the concomitant increase in uv-B radiation would also stress natural ecosystems. As in agriculture, individual species of plants and animals differ considerably in their sensitivities to uv-B radiation. However, in natural ecosystems a direct effect on only one species may be propagated to a large number of species because of complex interdependences. For example, the food chain of the oceans is based on photosynthesis by phytoplankton, and these microscopic, green plants have been demonstrated to be quite sensitive to uv radiation [66]. It was estimated from uv-B irradiation experiments that a 16 % ozone reduction (the degree of ozone depletion projected by the NAS study for continued release of chlorolluoromethanes) could kiU up to 50 % of the anchovies in the top 10 m of the clearest ocean water or else require them to substantially deepen their usual water depth [66, 67]. Avoidance could provide protection for many animals, but it is thought that few species can sense uv-B light. 

Nitrous oxide contributes severely to global warming and the depletion of ozone in the stratosphere (Crutzen 1981, Bouwman 1996). Almost 90% of the global atmospheric N2O is formed during the microbial transformation of nitrate (NO ) and ammonia (NH ) in soils and water. In OECD countries the agricultural contribution to N2O emissions is estimated at 58% (IPCC 2001). Soils fertilised with inorganic fertilisers and manure stores are seen as the largest sources (Chadwick et al. 1999, Brown ef al. 2002). 

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