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examBoard: Cambridge
examType: IGCSE
lessonTitle: Chemical and Building Materials from Oceans
Oceans cover more than 70% of our planet and contain a vast array of dissolved chemicals and compounds. For centuries, humans have extracted valuable chemical resources from seawater, with modern technology allowing us to harvest these resources more efficiently than ever before.
Key Definitions:
Salt is the most common chemical extracted from seawater. Seawater contains approximately 3.5% salt, of which about 85% is sodium chloride. The process of extracting salt from seawater, called solar evaporation, has been used for thousands of years.
The process works by:
Magnesium is the third most abundant element dissolved in seawater. It's extracted through a chemical process where seawater is treated with lime (calcium oxide) to precipitate magnesium hydroxide, which is then processed further to produce pure magnesium.
Uses include:
Beyond salt and magnesium, oceans contain many other valuable chemical elements that can be extracted:
Seawater contains about 65 parts per million of bromine. It's extracted by treating seawater with chlorine and then using air to separate the bromine. Used in flame retardants, pharmaceuticals and photography.
Extracted from seawater as potassium chloride. It's a critical component in fertilisers and is used in the production of glass, soap and various chemicals.
Though present in very low concentrations (about 3 parts per billion), research continues on economically viable methods to extract uranium from seawater as a potential future nuclear fuel source.
The ocean provides various materials that are used in construction and building. These range from traditional materials that have been used for centuries to modern innovations.
Marine sand and gravel are essential components in concrete production. They're extracted through dredging, where special vessels suck up material from the seabed.
Marine aggregates are sand and gravel extracted from the seabed. The UK alone extracts about 20 million tonnes of marine aggregates annually, accounting for about 20% of the sand and gravel used in England and Wales.
The extraction process involves:
Limestone from marine sources has been used as a building material for thousands of years. In some regions, coral has historically been harvested for building material, though this practice is now restricted due to environmental concerns.
Modern uses include:
While oceans provide valuable chemical and building materials, extraction activities can have significant environmental impacts if not managed properly.
The Dead Sea, located between Jordan and Israel, is one of the saltiest bodies of water on Earth with a salt concentration of about 34%. This makes it a rich source of minerals including:
Companies like the Dead Sea Works extract these minerals by pumping water into large evaporation ponds. As the water evaporates, different minerals crystallise at different rates, allowing them to be harvested separately.
However, this extraction, combined with diversion of water from the Jordan River, has contributed to the Dead Sea shrinking by about one metre per year, creating environmental challenges including sinkholes and habitat loss.
Scientists and engineers are developing new building materials derived from ocean resources that aim to be more sustainable:
Researchers are developing insulation materials and bioplastics from seaweed. These materials can be carbon-negative (absorbing more carbon than they release) and biodegradable.
Waste shells from seafood industries can be crushed and used as a partial replacement for traditional aggregates in concrete, reducing the need for quarried materials while recycling waste.
The UK has a long history of salt production, with evidence dating back to the Iron Age. Today, most UK salt comes from underground deposits rather than seawater, but traditional sea salt production continues in places like Maldon in Essex and the Isle of Anglesey in Wales.
At Anglesey Sea Salt (Halen Môn), seawater is filtered and evaporated in a sustainable process that produces high-quality salt crystals prized by chefs worldwide. The company has developed methods that minimise environmental impact while creating a premium product that supports the local economy.
This demonstrates how traditional extraction methods can be updated with modern technology to create sustainable businesses based on ocean resources.
As we look to the future of extracting chemical and building materials from oceans, several key challenges and opportunities emerge:
As our understanding of ocean ecosystems improves and technology advances, we have the opportunity to develop more sustainable approaches to harvesting the chemical and building materials that oceans provide, ensuring these valuable resources remain available for future generations.
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