What impact does chemical pollution have on the marine ecosystem?

Chemical pollution refers to the threat posed by chemical contaminants to the health of marine ecosystems that can come from various sources such as industrial discharges, sewage discharges, agricultural runoff, and the use of chemicals in agriculture and fisheries, among others.

Pollutants include heavy metals, persistent organic compounds, pharmaceuticals, pesticides, and other synthetic chemicals.

What is its impact?

• Contamination of the food chain. Toxic substances accumulate in marine organisms, starting at the lowest levels of the food chain (such as phytoplankton) and moving up through the trophic levels, affecting fish, seabirds, and mammals.
• Diseases and mortality of marine life. They can cause disease, weaken immune systems, and cause the death of various marine species, including fish, invertebrates, and marine mammals.
• Loss of biodiversity. Prolonged exposure to chemical pollutants can lead to the decline or extinction of certain species, affecting biodiversity and the balance of marine ecosystems.
• Affecting reproduction and development. Many chemicals are toxic and interfere with the reproductive and developmental processes of marine organisms, causing deformities, reduced fertility, and lower survival rates of offspring.
• Damage to marine habitats. Sensitive ecosystems such as coral reefs, mangroves, and seagrass beds can be severely affected by chemical pollution, resulting in the degradation of these vital habitats.
• Bioaccumulation and biomagnification. Toxic substances tend to accumulate in organisms throughout their lives (bioaccumulation) and concentrate at higher levels in top predators through the food chain (biomagnification), causing more severe adverse effects in these animals.
• Alteration of ecosystem functions. Chemical contaminants can alter fundamental ecological processes such as photosynthesis, decomposition of organic matter, and predator-prey interactions, affecting the productivity and resilience of the marine ecosystem as a whole.

What are emerging pollutants?

Emerging pollutants are compounds of different origins and chemical nature, previously unknown or unrecognized as such, whose presence in the environment is not necessarily new, but there is concern about the possible consequences of their presence.

There are different types of emerging pollutants with different physical and chemical properties. These include organic substances that can be subdivided into bioaccumulative and persistent toxic substances, more polar substances (pesticides, pharmaceuticals, industrial chemicals), and particulate pollutants (nanoparticles and microplastics).

The most representative examples of emerging pollutants are:

• Pesticides or pesticides.
• Hygiene products.
• Medicines.
• Creams, ointments, lotions.
• Illegal drugs.
• Endocrine or hormonal disruptors.
• Plasticizers and industrial additives.
• Nanoparticles of silver, gold, and metal oxides from industrial activities.
• Detergents or cleaning products.
• Microplastics

Most of these compounds are removed in Waste Water Treatment Plants (WWTP), using physical processes such as microfiltration or adsorption, biological processes such as membrane bioreactors, or advanced homogeneous and heterogeneous oxidation processes, among others.

The European Commission adopts every two years the Watch List of emerging pollutants to be analyzed in each Member State. The Member States must analyze and send the results of this monitoring to the European Commission. With this information, the Commission assesses whether the pollutants on the Watch List should be included in the Priority Substances List.

Example: Most of the world's rivers are flooded with antibiotics

Every year, humans produce, prescribe and ingest more antibiotics than the year before. These drugs have done wonders for public health by saving millions of people from infections, but the drugs' influence persists in the environment long after they have done their duty in the human body, seeping into the outside world, where their presence can stunt the development of antibiotic-resistant strains of bacteria and upset the delicate biological balance of rivers and streams, subsequently affecting seas and oceans as the water they carry flows into them, spreading globally.

Fish have been found with antidepressants, antibiotics and sunscreens that have caused side effects in their plasma, brain and liver.

The body does not break down the drugs, so the excess comes out as urine or waste. In many developed countries, the waste (and its antibiotic load) passes through a sewage treatment plant, but even the most modern plants do not clean up all the drugs. In places without treatment plants, antibiotics can flow more directly into rivers and streams.

One of the biggest problems for scientists is that no one has an accurate picture of when, where and how much antibiotics flow into the natural world. Many countries have little or no data on antibiotic concentrations in their rivers.

What can nuclear technology do?

The solution to the problems generated by pollution begins with an environmental diagnosis, using nuclear and conventional techniques, and the evaluation of mitigation and/or remediation measures to protect ecosystems, which implies constant monitoring of the state of the environment.

One example is the Marine-Coastal Stressors Research Network in Latin America and the Caribbean (REMARCO), which uses nuclear and isotopic techniques to obtain scientific information and help define policies that serve as a focus for action.

The network's research output allows the identification of heavy metal and radionuclide enrichment, the concentration of heavy metals and metalloids, persistent organic compounds such as petroleum hydrocarbons and pesticides, and nutrients, among others, from natural sources and pollution from human activity. It also provides tools for monitoring the impact of policies and verifying their effectiveness.

To determine the age of sediments in order to reconstruct long-term contamination trends, i.e. over 110 years, they use alpha particle and gamma spectrometry.

X-ray fluorescence spectrometry is used to determine the concentration of major elements and metallic contaminants, while mass spectrometry is used to study stable isotopes of carbon and nitrogen and to identify sources of organic matter contamination.