Changing Arctic Carbon cycle in the cOastal Ocean Near-shore (CACOON)

点击翻译按钮获取中文摘要

Global climate change has led to substantial increases in air temperatures across the Earth, particularly in Arctic regions. This has led to changes in patterns of rainfall and snow cover, as well as the structure and stability of terrestrial systems. Unlike the tropics - where the majority of land-based carbon is usually stored in trees on land, the Arctic plays host to vast quantities of carbon locked up underground in frozen soils and ice, known as permafrost. This permafrost has been locked up for tens of thousands of years, and still often contains the remains of woolly mammoth, and exotic viruses [1]. The Arctic Ocean (AO) receives huge quantities of material from the Arctic mainland, much being delivered by giant Arctic rivers that drain vast swathes of the Eurasian and American Arctic. These rivers are now delivering greater quantities of water from land to the ocean, fuelled by climate-driven increases in rainfall and permafrost thaw. This will cause a shift in the amount, age and type of materials being delivered from land to the ocean. So, should why is this important? The AO plays a crucial role in the storage and cycling of carbon, through the uptake of CO2 by marine plants, and the subsequent export of a fraction of this to the deep ocean - locking away carbon from the atmosphere. The ocean also plays host to bacteria (and other processes), which can release carbon from the ocean to the atmosphere. The balance of these processes is critical in determining how much carbon the AO will store, or release, in the future. Currently, we think the AO is a small overall 'store' of CO2 over the year, but this could change in the future, with hazardous consequences for global temperatures. We will examine these processes, focusing upon coastal regions where freshwaters meet the ocean. Studies to date, have focused upon rivers only, or the ocean itself, but few have investigated where they mix. We propose to carry out three different strands of research that will fill these gaps in our knowledge. We will study the East Siberian Shelf Sea (ESAS) region, and two very large Arctic river systems (the Kolyma and Lena Rivers) that drain into the AO over this shelf. We'll focus on this remote Russian Arctic area as it is currently experiencing extremely rapid climate warming, riverine runoff rates are increasing fast here, and despite the shelf covering a very large area little is known about how this region will change. Firstly, we'll conduct field campaigns collecting waters across the two study sites, sampling waters, soils and sediments during winter, summer and spring. This will involve sampling by boat in summer, and by skidoo - with drilling over ice during the Siberian winter. Secondly, we'll bring samples back from the field to conduct detailed experiments to determine how key environmental processes, such as sunlight and bacteria, use and alter terrestrial materials as they move from the rivers into the AO. This includes shining artificial sunlight at waters to see how materials change, or allowing microbes to 'feed' on what's in the water to see what they use and how quickly. Lastly, we'll combine our findings to develop modelling tools allowing us to model, or 'simulate', how fluxes of water, and materials travel from land-to-ocean over the ESAS. This model will contain separate compartments, representing different fractions of the materials sourced from land, for example different nutrients or carbon types. Also, it will simulate the major (small to microscopic) biological groups within the ecosystem, for example bacteria, and different phytoplankton groups. This will allow us to examine how the AO, and its biological processes will respond to future changes in freshwater supply and increased permafrost, and ultimately identify how these processes may alter the role of the AO in global climate.[1] http://www.bbc.com/earth/story/20170504-there-are-diseases-hidden-in-ice-and-they-are-waking-up