The Distribution and Vertical Transport of Resources in the Upper Ocean
Marine phytoplankton support higher trophic levels and are a key component of the biological carbon pump. The growth of marine phytoplankton is supported by the availability of bio-essential resources and incident light in the upper ocean. Over long periods, the biological carbon pump is sustained b...
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| Other Authors: | , |
| Format: | Thesis |
| Language: | English |
| Published: |
2021
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| Subjects: | |
| Online Access: | http://livrepository.liverpool.ac.uk/3123760/ http://livrepository.liverpool.ac.uk/3123760/1/200860898_Jan2021.pdf |
| Summary: | Marine phytoplankton support higher trophic levels and are a key component of the biological carbon pump. The growth of marine phytoplankton is supported by the availability of bio-essential resources and incident light in the upper ocean. Over long periods, the biological carbon pump is sustained by the replenishment of depleted resources. In winter, the deepening of the mixed layer entrains underlying waters, transferring resources between the seasonal thermocline and mixed layer. The transfer of properties by entrainment is augmented by other physical processes, such as diapycnal diffusion and aeolian deposition. This thesis aims to synthesise and exploit new datasets in the Atlantic Ocean and Equatorial Pacific Ocean to quantify mixed-layer resource availability and physical resource transfers into the upper ocean. The availability of resources in the winter mixed-layer is quantified by combining observational data from the GEOTRACES programme with mixed layer estimates from a global data assimilation model. Basin-scale patterns in the availability of nitrate, phosphate, silicic acid, cadmium, zinc, cobalt, iron and manganese throughout the Atlantic Ocean mixed-layer are identified. Relative to phosphate, we show that the subtropical North Atlantic is depleted in nitrate and cadmium, while enriched in silicic acid, zinc, cobalt, iron and manganese, with the reverse true in high latitudes. Intermediate conditions in relative resource availability are located in mid latitudes. Differences in the availability of each resource are linked to the vertical structure, where mixed-layer resource stoichiometry is governed by offsets in nutricline depths between resources. We note a coupling of silicic acid and zinc vertical profiles in the subtropical North Atlantic, in contrast to recent works highlighting the rapid recycling of zinc compared to silicic acid; however, we suggest that reversible scavenging plays a crucial role in setting the zinc vertical profile in the deep water column, causing an alignment with ... |
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