- Science

Explain the reason for the high mercury content in marine fish

The mercury content – an organic compound that can cause serious brain and nervous system damage – has increased by 23% in cod and 27% in Atlantic bluefin tuna.

Climate change and overfishing are increasing mercury levels in cod and tuna. This can cause neurological disorders in young children and babies whose mothers ate fish during pregnancy.

The Harvard researchers’ study was published in the journal Nature.

The mercury content – an organic compound that can cause serious brain and nervous system damage – has increased by 23% in cod and 27% in bluefin tuna caught in the Maine Bay of the Atlantic Ocean in about 3 decades ago.

Co-author of the study, professor of environmental chemistry at Harvard Medical School Elsie Sunderland, said mercury was extremely toxic during the last three months of pregnancy when the fetal brain was developing rapidly.

Pregnant women have long been advised to avoid foods made from swordfish and shark meat due to their high mercury content, but cod is a type of fish that experts say is rich and nutritious. Protein can support fetal development.

However, Professor Sunderland said that consumers should not be too scared after reading this study, as seafood is still a source of nutritious and healthy food.

Researchers just want to prove that climate change can directly affect food, followed by human health … not just extreme weather, floods and sea level rise. .

Warming seawater increases the energy needs of small fish, so they eat more mercury-containing bait. These small fish are then eaten by tuna, causing mercury accumulation in tuna is increasing.

Overfishing of herring and sardines also changes the eating habits of Atlantic cod, forcing them to feed on herring and lobsters, which are high in mercury.

According to the United Nations Food and Agriculture Organization, global fish consumption has more than doubled since the 1960s to a record 20.2kg / person / year, with 30% of the ocean being exploited. Excessive seafood.

Researcher Sunderland stressed that the situation could be more serious in the United States if US President Donald Trump reduced mercury emissions from thermal power plants, which took effect under his predecessor Barack Obama.

A 2018 study by Harvard University experts shows that coal-fired power plants are the leading source of mercury-containing emissions in the United States, accounting for 40% of total emissions.

This exhaust then seeps into soil and water and is eaten by marine life. Therefore, Sunderland researcher calls for a reduction in mercury emissions, especially from coal-fired thermal power plants.

The factory turns seawater into 75,000 liters of drinking water a day

The nonprofit GivePower has built a solar-powered water desalination plant in the coastal region of Kiunga, Kenya.

GivePower organization’s water desalination plant has been in operation since July 2018. It can produce 75,000 liters of drinking water per day, enough for 25,000 users. Desalination technology is not new, but earlier plants used large pumps and were extremely energy-intensive. Therefore, operating costs are also very high. “You have to find a way to get water from the sea that can be applied on a large scale and towards sustainable development,” said Hayes Barnard, head of GivePower.

The plant is solar-powered, uses Tesla batteries to store energy and has two pumps installed in parallel, helping to maintain continuous operation, even when a pump needs maintenance. In the future, GivePower hopes to build smaller desalination facilities, using just one pump and equipped with a 15 kW solar power system and Tesla batteries. GivePower can combine these facilities to increase scale. Locals only need to pay around US $ 0.0025 per liter of water.

Kiunga was the first place GivePower set up the factory. The construction process lasts a month at a total cost of 500,000 USD. The organization hopes to earn $ 100,000 a year from the factory and use that money to build additional facilities. Barnard aims to reduce construction costs to $ 100,000 per factory in the future.

Initially, GivePower focused on building solar battery systems to supply electricity in developing countries. The organization has installed solar battery systems in more than 2,650 locations in 17 countries, primarily including schools, clinics and villages. However, realizing that water shortages are a serious problem, GivePower continues to find ways to create clean water.

About a third of the world’s population cannot access safe drinking water, according to the United Nations Children’s Fund (UNICEF) and the World Health Organization (WHO). By 2025, half of the world’s population is expected to live in areas of water shortage. Some cities such as Cape Town (South Africa), Chennai (India) and Beijing (China) are facing reduced water supplies.

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