Ultraviolet radiation has a profound effect on many processes related to the carbon cycle. It can impede photosynthesis in plants and algae, particularly in phytoplankton, which produces around half of the oxygen in the atmosphere. UV rays can penetrate aquatic environments, although transparency varies. Pure water is transparent to UV rays, so in clear water (e.g.
alpine lakes), much of the upper layer is exposed to UV rays. The primary biological impacts of UV exposure on aquatic ecosystems is the reduction of the rate of photosynthesis. This can have a direct effect on primary productivity and, since different species may differ in their sensitivity to UV exposure, it may eventually affect biodiversity. Research at the SERC Photobiology Laboratory examines the effects of UV rays on many types of planktonic organisms, particularly microalgae in suspension (phytoplankton), as well as on benthic macroalgae (e.g.
seaweed). UV-B radiation can also alter the flowering time and the number of flowers in certain species. Altering flowering time can have a serious impact on plants because the availability of pollinators can be affected later on. Anther walls can absorb more than 98% of incident UV-B radiation and pollen walls contain compounds that absorb UV-B rays.
However, after transfer to the stigma, pollen may be susceptible to UV-B radiation. In populations of desert plants that reproduce sexually, the effects of UV-B radiation on growth and biomass appear to accumulate in subsequent generations that were exposed to UV-B radiation. Therefore, the effects of exposure to UV-B radiation can be amplified. UV radiation is generally affected by changes in stratospheric ozone and global climate change.
The decrease in stratospheric ozone allows more UVB rays (the most harmful and most common type of UV) to reach the Earth's surface. On the other hand, increased cloud cover, pollution, dust, wildfire smoke, and other particles carried by air and water related to climate change decrease the penetration of ultraviolet light.The National Meteorological Services' UV Index predicts the next day's UV radiation levels on a scale of 1 to 11+. Although molecular analyses of skin cancers have identified key somatic changes in several genes, it remains largely unknown if UV radiation caused these changes, how or to what extent, with the notable exception of mutations in the p53 tumor-suppressing genes of skin carcinomas, which show a clear UV signature. Preventing the negative health effects of UV rays includes a dual policy approach, with the objective of reducing UV radiation itself, on one hand, and increasing awareness of the health risks derived from exposure to UV rays, on the other hand. The intensity of solar UV light decreases rapidly with depth in the atmosphere due to absorption and dispersion by atmospheric gases while numerical density of O2 molecules decreases exponentially with height. This web page provides daily UV Index data in map and text form for major cities in the United States and shows frequently asked questions about the UV index as well as maps of current and expected UV levels in the United States. It is important to understand how ultraviolet light affects our environment so that we can take steps to protect it from further damage.
Ultraviolet light has been linked to a number of environmental issues such as reduced photosynthesis rates in plants and algae, altered flowering times and numbers of flowers in certain species, increased risk for skin cancer due to decreased stratospheric ozone levels, and decreased penetration due to increased cloud cover and air pollution. We must take steps to reduce our exposure to ultraviolet light by using sunscreen when outdoors for extended periods of time and wearing protective clothing when possible. We must also take steps to reduce air pollution levels so that ultraviolet light can penetrate deeper into our atmosphere. Finally, we must continue to monitor ultraviolet light levels so that we can take appropriate action if necessary.
