Isotopic characterisation of nutrient dynamics and UCDW behaviour in the west Antarctic Peninsula sea ice environment

南极半岛西部海冰环境营养物动态和 UCDW 行为的同位素表征

基本信息

批准号：
NE/K010034/1
负责人：
Sian Henley
金额：
$ 54.51万
依托单位：
University of Edinburgh
依托单位国家：
英国
项目类别：
Fellowship
财政年份：
2013
资助国家：
英国
起止时间：
2013 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FK010034%2F1
关键词：
Isotopic characterisation nutrient dynamics UCDW

项目摘要

This research project aims to examine the ways in which ongoing climate change and sea ice decline at the west Antarctic Peninsula (WAP) are impacting upon nutrient budgets and biogeochemical cycling throughout the region. The WAP is an ecologically important region of high primary productivity, and nutrient cycling is known to be crucial to phytoplankton production and its relationship with CO2 dynamics. Upper circumpolar deep water (UCDW) is understood to constitute the principal source of nutrients to surface waters throughout the WAP region. UCDW incurs at the shelf break and is transported across the continental shelf, so that nutrients can be supplied to the mixed layer by vertical mixing. This source of nutrients fuels high productivity in coastal regions, with implications for the biological uptake of atmospheric CO2.Available evidence suggests that sea ice variability can drastically impact phytoplankton biomass and nutrient utilisation in surface waters during the summer growing seasons, but the mechanisms underlying this interaction remain to be fully understood. Sea ice melt and meteoric freshwater inputs can promote phytoplankton blooms by stabilising the upper ocean sufficiently to provide a well-lit surface environment conducive to growth. However, such stratified conditions can also inhibit productivity and the magnitude of the bloom by restricting the resupply of nutrients to the mixed layer. Superimposed onto large interannual variability in chlorophyll, macronutrients and the physical environment, there are strong indications of long-term sea ice decline along the WAP and a concomitant decline in productivity.This research project seeks to understand the changes in nutrient biogeochemistry underlying these changes in productivity in the WAP sea ice zone, and addresses the central hypothesis that a climate-induced reduction in sea ice and stratification will result in drastic declines in primary production and nitrate utilisation in the surface environment. Such conditions would lead to a simultaneous reduction in the capacity of the oceanic CO2 sink during summer and generate an increased pool of unutilised nitrate in surface waters over the shelf, both of which would hold profound implications for global biogeochemical cycles.This study will comprise three components:1. A time-series study over three austral summer growing seasons in Ryder Bay, WAP, to examine temporal changes in fixed nitrogen budgets and cycling, in relation to interannual variability in sea ice, water column structure and productivity.2. A ship-based transect from the shelf break to Marguerite Bay to examine deep water behaviour and its impact on the supply of nutrients to high productivity coastal regions.3. Ship-based sampling across the wider WAP shelf region to examine spatial variability in nutrient dynamics, productivity, sea ice and physical oceanography, and give a broader context to the time-series study.A suite of biogeochemical measurements pertinent to nutrient budgets and cycling will be made during each component of the study. Comprehensive ancillary physical and biological data are available from project partners, to examine productivity and environmental variables alongside these nutrient measurements. A fixed nitrogen budget will be constructed for the WAP shelf on an annual basis and its interannual variability examined in the context of ongoing sea ice losses and changes in phytoplankton productivity. Nutrient biogeochemistry is central to the relationship between productivity and oceanic uptake of atmospheric CO2, so this study has broad and far-reaching implications for the role of the Southern Ocean CO2 system in regulating global climate. This study will also help to predict the future response of the oceans to ongoing climate change at the wider scale by giving insight into the climatic impacts on nutrient cycling and productivity in the fastest-warming marine environment on Earth.

该研究项目旨在研究西南极半岛（WAP）正在进行的气候变化和海冰的持续变化方式对整个地区的营养预算和生物地球化学循环产生影响。 WAP是高主要生产力的生态重要区域，众所周知，营养循环对于浮游植物的生产至关重要及其与CO2动力学的关系。可以理解，上近极深水（UCDW）构成了整个WAP区域的地表水的主要养分来源。 UCDW在架子上断裂并在大陆架上运输，因此可以通过垂直混合供应营养物质。这种营养素的来源为沿海地区的生产力提供了高生产率，这对大气的生物吸收的影响。可见的证据表明，海冰可变性可以极大地影响浮游植物生物量和夏季生长季节中地表水中的营养利用，但是这种交互的机制仍然是充分理解的。海冰融化和陨石的淡水输入可以通过充分稳定上海洋来促进浮游植物的开花，从而提供有利于生长的光线表面环境。但是，这种分层的条件也可以通过将营养素的补给限制在混合层来抑制生产率和开花的大小。 Superimposed onto large interannual variability in chlorophyll, macronutrients and the physical environment, there are strong indications of long-term sea ice decline along the WAP and a concomitant decline in productivity.This research project seeks to understand the changes in nutrient biogeochemistry underlying these changes in productivity in the WAP sea ice zone, and addresses the central hypothesis that a climate-induced reduction in sea ice and stratification will result in drastic在表面环境中，初级生产和硝酸盐利用率下降。这种条件将导致夏季海洋二氧化碳下沉的能力同时降低，并在架子上的地表水中产生增加的未利用硝酸盐池，这两种硝酸盐对全球生物地球化学周期都有深远的影响。这项研究将构成三个组成部分：1：1。 WAP莱德湾的三个澳大利亚夏季生长季节的一项时间序列研究，以检查固定氮预算和骑自行车的时间变化，与海冰，水柱结构和生产力的年际变化有关。2。从货架上断裂到玛格丽特湾的一种基于船舶的样品，以检查深水行为及其对高生产率沿海地区养分供应的影响3。基于船舶的采样跨越更广泛的WAP架子区域，以检查营养动态，生产力，海冰和物理海洋学的空间变异性，并为时间序列研究提供更广泛的背景。在研究的每个组成部分期间，将制定与营养预算和循环的生物地球化学测量套件。项目合作伙伴可以从项目合作伙伴那里获得全面的辅助物理和生物学数据，以检查生产力和环境变量以及这些养分测量。每年将为WAP货架建造固定的氮预算，并在持续的海冰损失和浮游植物生产力变化的背景下检查其年际变化。营养生物地球化学对于生产力与大气二氧化碳的海洋吸收之间的关系至关重要，因此，这项研究对南方海洋二氧化碳系统在调节全球气候中的作用具有广泛而深远的影响。这项研究还将有助于通过深入了解地球上最快的海洋环境中对养分循环和生产率的气候影响，从而预测海洋对持续气候变化的未来反应。