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Effects of UV-B radiation on photosynthesis and …

Such an experiment suggeststhe effect of UV-B radiation was mediated through changes in the host planttissues.

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UV-B RADIATION EFFECTS ON PHOTOSYNTHESIS, …

Without the layer of ozone in the stratosphere to protect us fromexcessive amounts of UV-B radiation, life as we know it would not exist. Scientific concern over ozone depletion in the upper atmosphere hasprompted extensive efforts to assess the potential damage to life onEarth due to increased levels of UV-B radiation. Some effects have beenstudied, but much remains to be learned.

T1 - Effects of UV-B radiation on terrestrial and aquatic primary producers

UV radiation from the sun has always played important roles in ourenvironment, and affects nearly all living organisms. Biologicalactions of many kinds have evolved to deal with it. Yet UV radiation atdifferent wavelengths differs in its effects, and we have to live withthe harmful effects as well as the helpful ones. Radiation at thelonger UV wavelengths of 320-400 nm, called UV-A, plays a helpfuland essential role in formation of Vitamin D by the skin, and plays aharmful role in that it causes sunburn on human skin and cataracts inour eyes. The incoming radiation at shorter wavelengths, 290-320 nm, falls within the UV-B part of the electromagnetic spectrum. (UV-B includes light with wavelengths down to 280 nm, but little to no radiation below 290 nm reaches the Earth’s surface). UV-B causes damage at the molecular level to the fundamental buildingblock of life— deoxyribonucleic acid (DNA).

Effects of UV-B Radiation on Photosynthesis - …

The effects of UV-B radiation on human skin are varied andwidespread. UV-B induces skin cancer by causing mutation in DNA andsuppressing certain activities of the immune system. The United NationsEnvironment Program estimates that a sustained 1 percent depletion of ozone will ultimately lead to a 2-3 percent increase in the incidence ofnon-melanoma skin cancer. UV-B may also suppress the body’s immuneresponse to Herpes simplex virus and to skin lesion development, and maysimilarly harm the spleen.

In the Antarctic, increased exposure to UV-B radiation due to theappearance of the ozone hole commonly results in at least a 6-12 percentreduction in photosynthesis by phytoplankton in surface waters. In astudy of California coastal waters, effects of current levels of UV-Bradiation compared to historical levels range from 40 percent reductionof photosynthesis by phytoplankton to a 10 percent increase. In fact,phytoplankton off the California coast sometimes turn out to be moresusceptible to UV-B radiation than phytoplankton in Antarctica, to thesurprise of biologists.

Effects of UV-B Radiation on Photosynthesis | …

Ozone depletion by anthropogenic gases has increased the atmospheric transmission of solar ultraviolet-B radiation (UV-B, 280-315 nm). Our understanding of the consequencences of enhanced UV-B levels on primary producers has grown dramatically over the past 20 years, but it has been hampered by how realistically experimental UV-B exposures mimic ozone-depletion scenarios. Overcoming these shortcomings will require sophisticated and creative approaches. Biological weighting functions and solar spectral irradiance estimates are critical in evaluating effects and require more attention. Whereas UV screening compounds in terrestrial and aquatic producers commonly increase with UV-B exposure, the implications, while potentially far reaching, are unclear. Photosynthesis is more sensitive to UV-B in phytoplankton than in terrestrial plants, probably owing to less effective screening in phytoplankton. Productivity of terrestrial plants is usually unaffected by enhanced UV-B, although reduced growth has been observed and may increase in magnitude over successive years. Aquatic productivity is often compromised by short-term exposures to enhanced UV-B, and long-term assessments are complicated by the dynamic nature of aquatic systems and by nonlinear responses. Recent work examining UV-B effects on multiple trophic levels suggests that outcomes will be diverse and difficult to predict. Such effects may lead to feedbacks on primary producers.

N2 - Ozone depletion by anthropogenic gases has increased the atmospheric transmission of solar ultraviolet-B radiation (UV-B, 280-315 nm). Our understanding of the consequencences of enhanced UV-B levels on primary producers has grown dramatically over the past 20 years, but it has been hampered by how realistically experimental UV-B exposures mimic ozone-depletion scenarios. Overcoming these shortcomings will require sophisticated and creative approaches. Biological weighting functions and solar spectral irradiance estimates are critical in evaluating effects and require more attention. Whereas UV screening compounds in terrestrial and aquatic producers commonly increase with UV-B exposure, the implications, while potentially far reaching, are unclear. Photosynthesis is more sensitive to UV-B in phytoplankton than in terrestrial plants, probably owing to less effective screening in phytoplankton. Productivity of terrestrial plants is usually unaffected by enhanced UV-B, although reduced growth has been observed and may increase in magnitude over successive years. Aquatic productivity is often compromised by short-term exposures to enhanced UV-B, and long-term assessments are complicated by the dynamic nature of aquatic systems and by nonlinear responses. Recent work examining UV-B effects on multiple trophic levels suggests that outcomes will be diverse and difficult to predict. Such effects may lead to feedbacks on primary producers.

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  • The effects of UV-B radiation on ..

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    These results indicate that the effects of UV-Bradiation on photosynthesis of W.

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Crop Science Abstract - Effects of UV-B Radiation on …

We know that increased exposure to UV-B radiation has specificeffects on human health, crops, terrestrial ecosystems, aquaticecosystems, and biogeochemical cycles. (“Biogeochemical cycles” refersto the cycling of chemicals such as carbon and energy throughout theEarth system.) This article will touch briefly on these effects, thenwill explain what determines how much UV we are getting and how weknow.

Long-term effects of elevated UV-B radiation on ..

AB - Ozone depletion by anthropogenic gases has increased the atmospheric transmission of solar ultraviolet-B radiation (UV-B, 280-315 nm). Our understanding of the consequencences of enhanced UV-B levels on primary producers has grown dramatically over the past 20 years, but it has been hampered by how realistically experimental UV-B exposures mimic ozone-depletion scenarios. Overcoming these shortcomings will require sophisticated and creative approaches. Biological weighting functions and solar spectral irradiance estimates are critical in evaluating effects and require more attention. Whereas UV screening compounds in terrestrial and aquatic producers commonly increase with UV-B exposure, the implications, while potentially far reaching, are unclear. Photosynthesis is more sensitive to UV-B in phytoplankton than in terrestrial plants, probably owing to less effective screening in phytoplankton. Productivity of terrestrial plants is usually unaffected by enhanced UV-B, although reduced growth has been observed and may increase in magnitude over successive years. Aquatic productivity is often compromised by short-term exposures to enhanced UV-B, and long-term assessments are complicated by the dynamic nature of aquatic systems and by nonlinear responses. Recent work examining UV-B effects on multiple trophic levels suggests that outcomes will be diverse and difficult to predict. Such effects may lead to feedbacks on primary producers.

Ecosystem-level UV-B Radiation Effects Involving Higher Plants

T1 - The effects of UV-B radiation on photosynthesis in relation to Photosystem II photochemistry, thermal dissipation and antioxidant defenses in winter wheat (Triticum aestivum L.) seedlings at different growth temperatures

Ecosystem-level UV-B Radiation Effects Involving Higher ..

Responses of beech seedlings to supplemental UV-B radiation were investigated during three consecutive seasons, in three repeated experiments. Our attention was paid on the alteration of the photosynthetic pigment composition - especially on the xanthophyll cycle pigments - chlorophyll fluorescence parameters, furthermore the accumulation of UV-B absorbing compounds in leaves, the specific leaf mass and leaf water content. The enhanced UV-B radiation generally affected significantly neither photochemical efficiency of PSII, nor photosynthetic pigment composition. UV-B radiation induced some protective mechanisms, thus VAZ-pool increased in beech leaves in every experiment, parallel with the enhancement of non-photochemical quenching. Amount of UV-B absorbing compounds in leaves increased under enhanced UV-B, but no significant changes were observed in the specific leaf mass. Sensitivity of plants to UV-B is largely influenced by other environmental factors and experimental conditions.

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