About This Project

Seaweed (macroalgae) are excellent biomonitors of the amount and type of nitrogen pollution (e.g., sewage versus chemical fertilisers). The UK is currently experiencing an environmental crisis – unregulated sewage release into river and coastal ecosystems. This project will combine nitrogen isotope monitoring of pollution with seaweed aquaculture in the River Tees estuary to determine its effectiveness in bioremediation, including carbon capture in nitrogen-rich polluted marine waters.

Ask the Scientists

What is the context of this research?

Seaweed (macroalgae) are excellent biomonitors of the amount and type of nitrogen pollution (e.g., sewage effluent versus chemical fertilisers) in estuary and coastal environments using stable nitrogen isotope ratios (expressed as δ¹⁵N). In addition, macroalgae are very effective in taking up nitrogen from seawater. Installing macroalgae aquaculture in estuaries is an effective, natural process to remove excess nitrogen being delivered from sewage and/or chemical fertilisers. This project will install seaweed ropes in nitrogen-excess regions to ascertain their effectiveness in nitrogen removal. Nitrogen isotope analysis of the seaweed and seawater can then be used to assess the effectiveness of the aquaculture in removing nitrogen prior to reaching the open sea.

What is the significance of this project?

In 2019 the UK had no river of “Good Chemical Status” and 86% of its rivers failed to obtain “Good Ecological Health” (The Rivers Trust, 2023). Declining standards and regulations for UK privatised water companies to effectively treat and limit the amount of wastewater discharge (i.e., sewage) has led to a water quality crisis in UK rivers and coastal environments (Environment Agency, 2022): this was highlighted in March 2023 by the BBC 2 documentary, Our Troubled Rivers. The environmental sewage crisis in the UK has led many charity groups, organisations and even individuals to start monitoring the environment themselves. Seaweed aquaculture around the UK could be used as a natural solution to remove excess nitrogen from estuary environments, including as a mechanism for carbon capture.

What are the goals of the project?

The project will use seaweed δ¹⁵N from around the River Tees estuary (NE England) to ascertain the type and distribution of nitrogen pollution (i.e., isoscape). Seaweed aquaculture ropes will be situated in elevated nitrogen zones in the estuary and monitored throughout a year: including nitrate δ¹⁵N and total nitrate analysis. Seasonal δ¹⁵N isoscape maps will be generated from seaweed to determine whether seaweed aquaculture is effectively removing nitrogen. The project will increase community education and environmental awareness of the problems facing coastal regions. Wider outreach will include a project dedicated website, Twitter, the Experiment project page and open-access publications. The purpose of this project to capture nitrogen will also allow us to assess carbon capture too.