Coastal pollution trends

Across the world, coastal regions and ecosystems are facing diverse environmental pressures from overexploitation, soil erosion, urban waste discharge and more. The consequences are equally wide-ranging: pollution in the marine environment can threaten the livelihoods of coastal communities and associated industries, pose a risk to human health through contaminated seafood, and affect marine ecosystems which provide valuable services.

As coastal pollution increases, knowledge on pollution levels and trends is becoming more crucial to protect marine ecosystems and resources. However, in many areas of the world, such information is either lacking or difficult to assess. Since both the levels and the type of marine contaminants can vary across regions, it is important that for the monitoring of coastal pollution to consider all these factors to ensure its effectiveness.

The IAEA Marine Environment Laboratories work with Member States — each facing their own unique challenges regarding marine pollution — to use nuclear and isotopic techniques for determining the temporal trends and sources of various contaminants in their marine environments. By using nuclear and isotopic techniques, scientists can analyse natural environmental archives like marine sediments, shells and corals to create a history of coastal pollution. Contaminants which end up in the marine environment accumulate layer by layer in, for example, the coastal sediments.

Nuclear techniques to measure pollution

Scientists can use the presence of lead-210, a naturally occurring radiotracer in the accumulated sediment, and its decay rate to calculate how old each layer is. Because lead-210 is particularly well-suited for radiometric dating of the last 100-150 years, it is very useful for analysing contaminants from a period where human activity is a dominant factor for pollution. Radiotracers present in the marine environment that are of anthropogenic (human-caused) origin can also be used in parallel to date the layers in marine sediments. Combined with other methods using various radionuclides and stable isotopes to detect organic and inorganic contaminants, scientists can construct a timeline of various pollutants entering the marine environment. This includes trace metals like cadmium, lead and mercury, and organic contaminants like pesticides, PCBs, or petroleum hydrocarbons from oil spills.    

The Laboratories work with Member States to enhance existing coastal pollution monitoring programmes as well as provide insight into temporal trends of pollution where monitoring data is missing. Understanding the behaviour of contaminants entering the marine environment in the past allows scientists to better predict the impact of future contamination events.