Collaborative Research: Using Geochemical Tracers to Characterize the Effects of Wintertime Episodic Nutrient Inputs on Biological Activity in the Sargasso Sea

最近的数据表明，马尾藻海天气锋的每周通过导致冬季混合期深层对流混合、养分输入和新产量增加。据推测，这些事件导致NO3输入到光区的增加，随之而来的是快速的生物反应和生物量的积累，以及同样快速的生物量输出到下面的水域。直接观察和量化这些潜在重要的营养注入事件具有挑战性，然而，更大的挑战是理解将这种营养输入最终与碳输出联系起来的机制。为了扩展M.W. Lomas等人的工作（“冬季混合期间增加的新产量是当前估算中缺失的组成部分”），伍兹霍尔海洋研究所和百慕大生物研究公司的研究人员将在先前资助的国家科学基金会项目中增加3He通量计技术（FGT）测量。FGT的加入将使研究人员能够更准确地确定和量化对流营养物供应、生物反应和大规模通量估算之间的重要联系，特别是在冬季混合期间，当两周一次的天气锋经过马尾藻海时。正是在这一时期，与深对流有关的偶发性营养输入随后出现了短时间的分层。注入的养分被迅速消耗，导致生物量积累，并在随后的对流混合事件中输出。总体结果是，短期但数量上重要的营养注射剂支持了出口生产的增加。为了使研究小组能够将这些通量的时间和大小与生态反应联系起来，研究人员将使用3He（以及3He:NO3比率）作为这些事件的示踪剂。这项研究的信息将进一步深入了解贫营养系统的初级生产和地下营养再矿化，这是海洋碳循环的核心组成部分，也是气候变化模型的重要组成部分。

ABSTRACTOCE-0351651 / OCE 0351396Recent data suggest that in the Sargasso Sea the weekly passage of weather fronts leads to increased deep convective mixing, nutrient inputs and new production during the winter mixing period. It has been hypothesized that these events lead to enhanced NO3 input into the euphotic zone, followed by a rapid biological response and accumulation of biomass, and an equally rapid export of that biomass to the waters below. Direct observation and quantification of these potentially important nutrient injection events is challenging, however, an even greater challenge is understanding the mechanisms that link this nutrient input ultimately to carbon export.To expand the work of M.W. Lomas, et al. ("Enhanced New Production During Winter Mixing A Missing Component of Current Estimates"), researchers at the Woods Hole Oceanographic Institution and the Bermuda Biological Station for Research Inc. will add 3He Flux Gauge Techniques (FGT) measurements to the previously funded NSF project. The addition of FGT will enable the researchers to more accurately determine and quantify the important linkages between convective nutrient supply, biological response, and large-scale flux estimates specifically during the period of winter mixing when bi-weekly weather fronts pass through the Sargasso Sea. It is during this period that episodic nutrient inputs associated with deep convection are followed by short periods of stratification. The injected nutrients are rapidly consumed resulting in biomass accumulation, which is exported during the subsequent convective mixing event. The overall result is enhanced export production supported by short-lived, but quantitatively important nutrient injections. To enable the team of researchers to link the timing and magnitude of these fluxes and the ecological response, the researchers will use 3He (and 3He:NO3 ratios) as a tracer of these events. The information from this study will offer further insight into primary production and subsurface nutrient remineralization in oligotrophic systems, which are a central component of the ocean carbon-cycle and an important part of climate change modeling.