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Decrease in the quantity of total-column ozone; tend to cause increased penetration of solar UV-B radiation (290-315nm) to the earth’s surface. UV-B radiation is the most energetic component of sunlight reaching the earth’s surface. It has profound effects on human health, animals, plants, micro-organisms, materials and on air quality.
Effects of human and animal health
♤ Potential risks include an increase in the incidence of and morbidity from eye diseases, skin cancer and infectious diseases.
♤ UV radiation has been shown in experimental systems to damage the cornea and lens of the eye. Experiments in animals show that UV exposure decreases the immune response to skin cancers, infectious agents and other antigens and can lead to unresponsiveness upon repeated challenges.
♤ In susceptible (light-skin coloured) populations, UV-B radiations is the key risk factor for development of nonmelanoma skin cancer (NMSC).
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All the chameleons have the ability to change color whenever they are subject to changes in stimuli, like a change in light, temperature or emotion. For example, when angered, they are likely to become darker in color.
Effects on terrestrial plants
♤ Psychological and developmental processes of plants are affected by UV-B radiation.
♤ Response to UV-B also varies considerably among species and also cultivars of the same species. In agriculture, this will necessitate using more UV-B tolerant cultivars and breeding new ones.
♤ In forests and grasslands, this is likely to result in changes in the composition of species; therefore there are implications for the biodiversity in different ecosystems.
♤ Indirect changes caused by UV-B such as changes in plant form, biomass allocation to parts of the plant, timing of developmental phases and second metabolism may be equally or sometimes more important that the damaging effects of UV-B.
Effects on aquatic ecosystems
♤ Exposure to solar UV-B radiation has been shown to affect both orientation mechanisms and motility in phytoplankton, resulting in reduced survival rates for these organisms.
♤ Solar UV-B radiation has been found to cause damage in the early developmental stages of fish, shrimp, crab, amphibians and other animals. The most severe effects are decreased reproductive capacity and impaired larval development.
Effects on bio-geochemical cycles
♤ Increases in solar UV radiation could affect terrestrial and aquatic bio-geochemical cycles, thus, altering both sources and sinks of greenhouse and chemically important trace gases.
♤ These potential changes would contribute to bio-sphere atmosphere feedbacks that reinforce the atmospheric build-up of these gases.
Effects on air quality
♤ Reduction in stratospheric ozone and the concomitant increase in UV-B radiation penetrating to the lower atmosphere result in higher photo dissociation rates of key trace gases that control the chemical reactivity of the troposphere.
♤ This can increase both production and destruction of ozone (O3) and related oxidants such as hydrogen peroxide (H2O2), which are known to have adverse effects on human health, terrestrial plants, and outdoor materials.
♤ Changes in the atmospheric concentrations of the hydroxyl radical (OH) may change the atmospheric lifetimes of climatically important gases such as methane (CH4) and the CFC substitutes.)
♤ Increased tropospheric reactivity could also lead to increased production of particulates such as cloud condensation nuclei, from the oxidation and subsequent nucleation of sulphur, of both antropogenic and natural origin (e.g. carbonyl sulphide and dimethylsulphide.
Effects on materials
♤ Synthetic polymers, naturally occurring bio-polymers, as well as some other materials of commercial interest are adversely affected by solar UV radiation.
♤ The application of these materials, particularly, plastics, in situations which demand routine exposure to sunlight is only possible through the use of light-stabilizers and / or surface treatment to protect them from sunlight.
♤ Any increase in solar UV-B content due to partial ozone depletion will therefore accelerate the photogradation rates of these materials, limiting their life outdoors.