Collaborative Research: Examination of the Potential Sources for the Mid-Water Silica Anomaly in the NE Pacific

合作研究：检查东北太平洋中层水体二氧化硅异常的潜在来源

• 批准号: 0452088
• 负责人: Douglas Hammond
• 金额: $ 9.61万
• 依托单位: University of Southern California
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-03-15 至 2008-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0452088&HistoricalAwards=false
• 关键词: Collaborative; Research; Examination; Potential; Sources

ABSTRACTOCE-0452565 / OCE-0452088Previous studies have shown that the North Pacific contains the highest deep-water concentrations of dissolved silica in the world ocean, and Cascadia Basin appears to be the source region for this global-scale anomaly. Data compilations indicate that a .plume. of dissolved silica originates from within this small marginal Basin, which can be traced for several thousand miles, from an origin in the NE Pacific to the Hawaiian Ridge in the south and almost to Siberia in the west. Box model calculations based on compiled data in the area indicate that the North Pacific deep-water silica anomaly requires a flux from Cascadia Basin of nearly 2 Tmols/year to sustain the observed concentration levels. If correct, this dissolved silica flux is an astonishing 40% of the total riverine silica input to the oceans, but this interpretation requires substantial verification. Although there are several identified sources for dissolved silica within the Basin, including ridge-axis vent fields, ridge-flank hydrothermal circulation, compression of sediments at the accretionary wedge and the upward diffusive flux from sediment pore waters, none of these processes, either individually or in aggregate, appear to be adequate to produce the observed deep-water silica anomaly. In this study, researchers at the University of Washington and the University of Southern California will conduct a field program to provide the required spatial distribution of CTD and Niskin/nutrient measurements needed to construct a reasonable silica inventory and geostrophic bottom water flux. They plan to (a) compile all existing CTD/nutrient data from Cascadia Basin, which is substantial in number, but limited in location, (b) add new data from cruises-of-opportunity in 2004, (c) map the geographic distribution and inventory of deep-water silica with 40 new hydrocast profiles from areas not sampled by existing data, (d) use the new data to determine the basin-scale pattern of bottom water circulation and (e) determine the Ge/Si ratios of the bottom water, to distinguish biological from geological source regions. The primary goals of the program are to quantify the flux of dissolved silica into the Basin and identify the source regions that are responsible.Broader Impacts: Large ocean-going field programs at UW support graduate and undergraduate students in their academic research, allow participation of additional non- Oceanography students from UW and from other institutions on the cruises, acquire data for student theses, and provide substantial out-reach in public awareness about scientific research. Further, although Cascadia Basin was poorly sampled by WOCE, the few data collected suggest a disproportionate role for this small basin in determining properties of the entire Pacific Deep Water.

ABSTRACTOCE-0452565 / OCE-0452088先前的研究表明，北太平洋深水区溶解二氧化硅的浓度是世界海洋中最高的，而卡斯卡迪亚盆地似乎是这种全球范围异常现象的源区。 数据汇编表明.plume。溶解的二氧化硅源自这个小型边缘盆地，其绵延数千英里，从东北太平洋的起源到南部的夏威夷海脊，几乎到西部的西伯利亚。 基于该地区汇编数据的箱模型计算表明，北太平洋深水二氧化硅异常需要来自卡斯卡迪亚盆地每年近 2 Tmol 的通量才能维持观测到的浓度水平。 如果正确的话，这种溶解的二氧化硅通量占流入海洋的河流二氧化硅总量的惊人 40%，但这种解释需要大量验证。 尽管盆地内溶解二氧化硅有几个已确定的来源，包括脊轴喷口场、脊侧热液循环、增生楔处沉积物的压缩以及沉积物孔隙水的向上扩散通量，但这些过程都不是单独的或者总的来说，似乎足以产生所观察到的深水二氧化硅异常。在这项研究中，华盛顿大学和南加州大学的研究人员将开展一项实地计划，以提供构建合理的二氧化硅库存和地转底层水通量所需的 CTD 和 Niskin/营养物测量所需的空间分布。他们计划 (a) 汇编来自卡斯卡迪亚盆地的所有现有 CTD/营养物数据，该盆地数量众多，但位置有限，(b) 添加 2004 年机会航行的新数据，(c) 绘制地理分布图和深水二氧化硅清单，其中包含来自现有数据未采样区域的 40 个新水力铸造剖面，(d) 使用新数据确定底部水循环的盆地规模模式，以及 (e) 确定底层水，以区分生物源区和地质源区。该计划的主要目标是量化进入盆地的溶解二氧化硅流量并确定造成影响的来源区域。 更广泛的影响：华盛顿大学的大型远洋实地计划支持研究生和本科生的学术研究，允许参与来自威斯康星大学和其他机构的其他非海洋学学生在巡游中获取学生论文的数据，并广泛宣传公众对科学研究的认识。此外，尽管 WOCE 对卡斯卡迪亚盆地的采样质量较差，但收集到的少量数据表明，这个小盆地在确定整个太平洋深水特性方面发挥着不成比例的作用。