DISTRIBUTION, COMPOSITION AND TRANSPORT OF DISSOLVED ORGANIC MATTER IN SHELF SEAS
For their size, shelf seas play a disproportionately large role in the oceanic carbon pump. While accounting for only 7% of the surface ocean, the amount of carbon exported from shelf seas contributes to between 20 and 50% of total oceanic CO2 storage (Tsunogai et al. 1999). In terms of their socio...
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| Format: | Thesis |
| Language: | English |
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2018
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| Online Access: | http://livrepository.liverpool.ac.uk/3028049/ http://livrepository.liverpool.ac.uk/3028049/1/200608952_Mar2018.pdf |
| Summary: | For their size, shelf seas play a disproportionately large role in the oceanic carbon pump. While accounting for only 7% of the surface ocean, the amount of carbon exported from shelf seas contributes to between 20 and 50% of total oceanic CO2 storage (Tsunogai et al. 1999). In terms of their socio economic importance, shelf seas support ~ 90% of global fish catches (Pauly et al. 2002), and future projections estimate that up to 4.2 billion people will live within 200 km of the coast by 2030 (Kummu et al. 2016). Shelf seas are the interface between land and ocean and high nutrient inputs and intense physical energy provided mainly by tidal mixing, help to maintain high biological activity on the shelf. Indeed, rates of primary production are up to 3 times greater in shelf seas than in the open ocean (Simpson and Sharples 2012). Through a process known as the continental shelf pump, over 40% of particulate organic matter produced on-shelf is exported to the adjacent ocean (Muller-Karger et al. 2005). The role of dissolved organic matter (DOM) in this pump, in particular, dissolved organic carbon (DOC), is less well understand, despite DOC concentrations in the ocean being 50 times more than carbon in the particulate pool (Eglinton and Repeta 2006), and the amount of carbon in the DOC pool being similar to that of carbon as CO2 in the atmosphere (Hansell and Carlson 1998). Here, to add to the growing body of work on the distribution of DOM in shelf seas, the main goals of this thesis were to (a) map the distribution of DOC and dissolved organic nitrogen (DON) across 5 shelf regions across the Northwest European shelf, and the adjacent North Atlantic; (b) to assess the distribution of DOC and DON in different regions over a seasonal cycle to see if they followed a typical seasonal cycle of production, consumption and loss; (c) to characterise the source of DOM in the Celtic Sea and determine how much of the DOC pool was of terrestrial origin; (d) to assess multi-year trends in DOC and DON in the North Sea ... |
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