Biological Effects of UV Radiation (SL IB Environmental Systems & Societies (ESS))

UV Radiation Effects on Humans

• Ultraviolet radiation from the Sun can have damaging effects on human living tissues
  • When excessive UV radiation reaches the surface of the Earth, it can lead to various health issues by damaging cells and tissues

   Cataracts

• • Prolonged exposure to UV radiation can contribute to the development of cataracts
  • Cataracts cause clouding of the lens in the eye, leading to blurry vision and eventual vision loss if left untreated

   UV radiation effects on cells

• • UV radiation has the potential to induce mutations in DNA during cell division
  • When skin cells are exposed to UV radiation, it can lead to genetic alterations and mutations, which can disrupt normal cell growth and increase the risk of developing cancer

   Skin cancer

• • UV radiation is a major risk factor for the development of skin cancer
  • UV rays can damage the DNA in skin cells, leading to uncontrolled cell growth and the formation of cancerous tumours
  • Prolonged or intense exposure to UV radiation, especially without proper protection, increases the risk of developing skin cancer

   

Photo by Dimitris Chapsoulas on Unsplash 

Measures such as wearing sunscreen with a high sun protection factor (SPF), using sunglasses that block certain UV rays, seeking shade during peak sun hours, and wearing protective clothing can help reduce the risk of UV-related health issues

   Sunburn

• • When the skin is exposed to excessive UV rays, it triggers an inflammatory response as a defence mechanism
  • Sunburned skin becomes red, painful, and may blister, indicating damage to the skin cells

   Premature skin ageing

• • Chronic exposure to UV radiation accelerates the ageing process of the skin
  • It can cause the breakdown of collagen and elastin fibres, leading to wrinkles, sagging skin, and the development of age spots

• Protecting the skin and eyes from excessive UV radiation is crucial to minimise the harmful effects
  • Measures such as wearing sunscreen with a high sun protection factor (SPF), using sunglasses that block certain UV rays, seeking shade during peak sun hours, and wearing protective clothing can help reduce the risk of UV-related health issues

• Regular skin examinations and eye check-ups can help detect any potential UV-related damage or abnormalities early on, allowing for timely intervention and treatment

Effects on Biological Productivity

• Exposure to increased ultraviolet radiation can have significant effects on biological productivity, particularly on photosynthetic organisms such as phytoplankton, which play a crucial role in aquatic food webs
  • Phytoplankton convert sunlight, carbon dioxide, and nutrients into organic matter through photosynthesis

• Increased UV radiation damages photosynthetic organisms, such as phytoplankton, by causing DNA damage and inhibiting photosynthesis
  • When exposed to increased UV radiation, phytoplankton may experience reduced photosynthetic activity and growth, leading to a decrease in primary productivity in aquatic ecosystems

Photo by USGS on Unsplash 

A population explosion, or bloom, of green phytoplankton, which form the first link in nearly all ocean food chains, can be seen from above swirling in the dark water around Gotland, a Swedish island in the Baltic Sea

• Phytoplankton play a vital role in nutrient cycling
  • They absorb nutrients from the water, convert them into biomass, and serve as a food source for other organisms
  • Reduced phytoplankton populations due to UV radiation damage can disrupt nutrient cycling processes, leading to imbalances and nutrient deficiencies in the ecosystem

• Reduced phytoplankton productivity can have cascading effects on higher trophic levels in aquatic ecosystems
  • Zooplankton, which feed on phytoplankton, may experience decreased food availability, affecting their growth and reproduction
  • This, in turn, can impact higher-level consumers, such as fish and marine mammals, which rely on phytoplankton and zooplankton as a food source

• Changes in phytoplankton productivity disrupts overall ecosystem dynamics and stability
• The depletion of the ozone layer, which filters harmful UV radiation, increases the impact of UV radiation on aquatic ecosystems
• Mitigating human activities that contribute to ozone depletion is therefore crucial for preserving the health and productivity of photosynthetic organisms and maintaining balanced aquatic ecosystems