Ozone, abiotic production

Effect of UV on Productivity of the Southern Ocean. Has ozone depletion over Antarctica affected the productivity of the Southern Ocean There is no easy answer. First, one has to take into account the fact that the drastic decrease of ozone over Antarctica has been reported as recently as 1976, a relatively short time in the evolution of the organisms to develop mechanisms to cope with elevated UV. One of the most vexing problems in studying the effects of UV radiation on productivity, is a dearth of historical data on the level of UV. Without these baselines, normal fluctuations could easily be interpreted as decline in productivity. Second, there is a host of biotic and abiotic factors that play significant roles in governing the productivity of the Southern Ocean (40). Ultraviolet radiation is but one more complicating factor to be considered in an already stressful environment. 

In long-term evolutionary scales, humans now have the abilities to intervene rapidly in this interdependent relationship and alter the stability of the rates of metabolism of organic matter. For example, reduction of ozone in the stratosphere and associated increased UV-B could lead to accelerated photolytic degradation of macromolecules of DOM to CO2 by both abiotic and biotic pathways. In addition, the photolytic enhancement of substrates for bacterial metabolism by UV photolysis can result in accelerated rates of biogeochemical cycling of nutrients and stimulated productivity of the ecosystems. In addition to decreasing the metabolic stability of the lakes and streams, the enhanced microbial respiration will certainly lead to increased generation of CO2 and evasion to the atmosphere. 

Most abiotic elimination techniques, which are normally used in wastewater treatment plants (WWTP) such as ozonation or adsorption on granular activated carbon, are not very effective for MTBE or its main degradation product, TBA removal [36,43]. These hmitations may generate additional problems for water suppliers and regulators since TBA may be considered even more toxic than its parental compound [44]. 

Photochemistry is also important in present-day planetary atmospheres. The best-known abiotic example is the production of ozone (O3) in the Earth s stratosphere, initiated by the photodissociation of O2 by ultraviolet sunlight ... 

Figure 1.14 Comparison of the most relevant ecological factors involved in the production of PLLA and fossil-based derived polymers. PED = primary renewable energy PED non-ren = primary nonrenewable energy GWP = global warming potential AP = acidification potential EP = eutrophication potential POCP = photochemical ozone creation potential ADP = abiotic resource depletion potential ...

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