The California Current transition zone off northern and central California: an extensive region exhibiting Fe-limitation and moderate chlorophyll

加利福尼亚州北部和中部附近的加利福尼亚洋流过渡区：表现出铁限制和叶绿素中等的广阔区域

• 批准号: 0849943
• 负责人: Kenneth Bruland
• 金额: $ 68.03万
• 依托单位: University of California-Santa Cruz
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-02-01 至 2013-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0849943&HistoricalAwards=false
• 关键词: California; Current; transition; zone; off

High nitrate levels observed offshore in the California Current (CC) transition zone filament waters originate from coastal upwelled waters that have become iron-limited according to a research at the University of California-Santa Cruz. This scientist further proposes that iron-limitation in the CC transition zone results in nitrate drawdown and biological responses on time scales of a few weeks to months. This slow drawdown of nitrate differs from near-shore regions located over a relatively broad continental shelf with an adequate supply of iron allowing a rapid phytoplankton bloom and drawdown of nitrate on time scales of a few days to a week. To determine the role of Fe limitation in controlling phytoplankton biomass in the California Current (CC) transition zone off northern and central California, a research cruise, proposed to take place in 2010 on the RV Point Sur, would be carried out to determine the following: (1) the sources of nutrients, micronutrients, and trace metals from various upwelling regions along the northern and central coasts of California; (2) whether elevated macronutrients in the CC transition zone are due to coastal upwelling and subsequent advection and mixing offshore versus upwelling off the shelf due to curl of the wind stress or eddy dynamics; (3) Fe limitation in the CC transition zone; (4) nutrient consumption patterns in the CC system relative to Fe availability; and (5) remineralization/solubilization and assimilation of leachable particulate Fe by the phytoplankton community using low abundance stable isotopes of Fe as tracers.As regards broader impact, this study would further our knowledge on what controls phytoplankton biomass and ecosystem productivity in eastern boundary current regions, an economically important area. In regards to educational impacts, this research would provide scientific training for a graduate student and a postdoc.

根据加州大学圣克鲁斯分校的一项研究，在加利福尼亚洋流（CC）过渡区观察到的高硝酸盐水平源于沿海上升流，这些上升流已经成为铁限制。这位科学家进一步提出，CC过渡区的铁限制导致硝酸盐减少和生物反应在几周到几个月的时间尺度上。这种硝酸盐的缓慢下降与位于相对宽阔的大陆架上的近岸地区不同，这些地区有足够的铁供应，允许浮游植物快速繁殖，硝酸盐在几天到一周的时间尺度上下降。为了确定铁限制在控制加州北部和中部加利福尼亚洋流过渡区浮游植物生物量中的作用，将于2010年在RV Point Sur进行一次研究巡航，以确定以下内容：(1)来自加利福尼亚北部和中部海岸不同上升流区域的营养物质、微量营养素和微量金属的来源；(2) CC过渡带中常量营养物质的升高是由于沿岸上升流和随后的海上平流和混合，还是由于风应力旋度或涡旋动力学引起的陆架外上升流；(3) CC过渡区Fe限制；(4) CC系统中与铁有效性相关的养分消耗模式；(5)浮游植物群落利用低丰度稳定铁同位素作为示踪剂对可浸颗粒铁的再矿化/增溶和同化。至于更广泛的影响，这项研究将进一步了解是什么控制了东部边界流区域浮游植物生物量和生态系统生产力，这是一个重要的经济区域。在教育影响方面，这项研究将为研究生和博士后提供科学培训。