Greenhouse gases in River Catchments to Coastal Seas
I am currently working toward a PhD in Environmental Sciences titled ‘Greenhouse Gases in River Catchments to Coastal Seas’. Over the next 3 years, this research will address knowledge gaps in the production and transport of greenhouse gases from freshwater systems into the coastal and marine environment. Greenhouse gases contribute to climate change by trapping heat in the atmosphere. Approximately 40% of methane (CH4) and 60% of nitrous oxide (N2O) come from natural sources which include soils, rivers, estuaries and oceans. Both are powerful greenhouse gases with a warming effect 298 and 30 times higher than carbon dioxide (CO2). They also affect stratospheric ozone depletion (N2O) and the ability of the atmosphere to cope with other pollutants (CH4), posing serious risks to human health by reducing our protection against skin damage caused by harmful UV. Despite the importance of these two gases, there are still many unanswered questions about their sources and sinks and their transport from river catchments to coastal waters.
The way we use the environment can cause changes to processes in the water which control our climate. When too many nutrients enter the water system from agriculture or wastewater treatment, there are more ingredients available to create more N2O and CH4. When we add low river flows and increasing summer temperatures to this scenario, it creates an ideal mixing bowl for tiny microbes to get cooking and pump these gases out into the atmosphere. This could change where see increasing 'hotspots' of natural greenhouse gas sources and risk our chances of transitioning to a net-zero emission society. It's important we monitor this so we can implement the most effective nature-based solutions, in the most effective places, in the most effective way.
So how do we do this? Every month, I'm out with my team collecting samples of river, estuary and seawater from the top of the River Tamar to Devils Point, Plymouth. When I get back to the lab, I use a method called continuous flow stable isotope mass spectrometry to find the unique 'fingerprint' of the greenhouse gas concentrations in the water. This fingerprint tells me more about how the gases were produced and from there we can start to understand what conditions could lead to increased or reduced greenhouse gas emissions now and into the future.