Beyond Iron in the Ocean: Trace metal micronutrients and the carbon cycle (BIO-Trace)

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项目编号	NE/P018181/1
	Beyond Iron in the Ocean: Trace metal micronutrients and the carbon cycle (BIO-Trace)
	Susan Halsall Little
主持机构	Imperial College London
项目开始年	2018
	2018
项目结束日期	2022-12-31
资助机构	UK-NERC
项目类别	Fellowship
项目经费	561233(GBP)
国家	英国
语种	英语
英文摘要	Microscopic plants in the ocean, called phytoplankton, are responsible for about half of the solar-powered photosynthesis on Earth. As they grow and reproduce, phytoplankton take up dissolved carbon dioxide (CO2) from the surface ocean, where it is in balance with atmospheric CO2 gas, and convert it into solid organic carbon. When they die, this organic matter sinks into the deep ocean, and is converted back to dissolved CO2 via grazing by other plankton and bacteria. This process, called the biological pump, removes CO2 from the surface ocean-atmospheric reservoir and transfers it to the deep ocean, where it may be trapped for several hundred, or even thousand, years. The biological pump is pivotal to Earth's climate. Without it, pre-Industrial Revolution levels of atmospheric CO2 would have been more than 50% higher than observed, while today the oceans have already absorbed about 30% of human CO2 emissions. The key aim of this project is to understand the processes that determine the efficiency of the biological pump. Like all living organisms, phytoplankton need a wide range of nutrients to grow, nutrients that they obtain from their external environment, i.e., from seawater. About 95% of all organic matter is made up of six 'macronutrients' (carbon, hydrogen, nitrogen, phosphorus, oxygen, and sulphur), which are used to make carbohydrates, proteins, fats, and nucleic acids (e.g., DNA). In addition, phytoplankton also require a range of trace metal 'micronutrients', which are used in an array of enzymes necessary to carry out the essential processes of life (including, for example, photosynthesis). The nutrient that is in shortest supply is called the 'limiting nutrient', because it limits phytoplankton growth and reproduction (or productivity). Limiting nutrients are one key control on the activity of the biological pump. For example, the micronutrient iron has long been known to be an important limiting nutrient in high latitude (polar) surface oceans. Other trace metals, like zinc, are likely also important, but have been less well studied. The distribution of nutrients in the ocean is controlled by a complex interplay of their inputs (such as dust), biological uptake and sinking (the biological pump), and their redistribution laterally and vertically in the ocean via the movement of packages of water, called water masses. Of particular importance to this interplay are geographic regions where an exchange between the surface and deep ocean occurs, typically in the high latitudes. One of these regions is the Southern Ocean. Here, deep water masses, with a high nutrient content, return to the surface, while other water masses sink back from the surface towards intermediate depths and flow equator-wards. Critically, nutrients supplied to the low latitudes in these intermediate depth water masses are a key control on global ocean productivity, and hence atmospheric CO2. In my project, I will identify links between micronutrient supply to the surface ocean, the complexity of the chemical forms of trace metals present in seawater, and the community of phytoplankton present in the high latitude surface ocean, and evaluate how these factors combine with the ocean circulation to set the global distribution of nutrients in the ocean. The result will be a coherent, in depth understanding of how micronutrient limitation of the biological pump in the high latitude oceans impacts whole ocean carbon cycling.
来源学科分类	Natural Environment Research
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/86997
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Susan Halsall Little.Beyond Iron in the Ocean: Trace metal micronutrients and the carbon cycle (BIO-Trace).2018.