...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Oceanographic Literature Review >Sediment geochemistry
【24h】

Sediment geochemistry

机译：沉积物地球化学

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The lagrangian progression of biogeochemical processes was followed in a filament of the Mauritanian upwelling system, North West Africa, during offshore advection. Inert duel tracers sulphur hexafluoride and helium-3 labelled a freshly upwelled patch of water that was mapped for 8 days. Changes in biological, physical and chemical characteristics were measured including phytoplankton productivity, nitrogen assimilation and regeneration. Freshly upwelled water contained high nutrient concentrations (NO_3~-= 9.0 ± 0.1 μmol L~(-1); PO_4~(3-)=0.7 ± 0.1 μmol L~(-1); Si = 2.7 ± 0.1 μmol L~(-1)) but was depleted in N compared to Redfield stoichiometry (N:P = 13.9:1). A maximum primary productivity rate of 0.7 mol C m~(-2) d~(-1) was measured on the continental shelf, associated with N-assimilation rates of 43.8 nmol L~(-1) h~(-1) for NO_3~-, 32.8 nmol L~(-1) h~(-1) for NH_4~+ and a phytoplankton community dominated by diatoms and flagellates. Indicators of phytoplankton abundance and activity decreased as the labelled water mass transited the continental shelf slope into deeper water, possibly linked to the mixed layer depth exceeding the light penetration depth. By the end of the study, primary productivity rates of 0.1 mol C m~(-2) d~(-1) were measured, associated with N-assimilation rates of 3.9 nmol L~(-1) h~(-1) for NO_3~-, 6.1 nmol L~(-1) h~(-1) for NH_4~+ and lower nutrient concentrations (NO_3~- = 4.6 ± 0.3 μmol L~(-1); PO_4~(3-)= 0.4 ± 0.1 μmol L~(-1); Si = 0.9 ± 0.1 μmol L~(-1)). Nitrogen regeneration and assimilation took place simultaneously; NH_4~+ was regenerated at 9.4-85.0 nmol L~(-1) h~(-1); NH_4~+ was oxidised at 0.30-8.75 nmol L~(-1) h~(-1); NO_2~- was oxidised at 25.55-81.11 nmol L~(-1) h~(-1). Results highlight the importance of regenerated NH_4~+ in sustaining phytoplankton productivity and indicate that the up-welled NO_3~- pool contained an increasing fraction of regenerated NO_3~- as it advected offshore. By calculating this fraction and incorporating it into an f ratio formulation we estimated that of the 12.38 Tg C of annual regional production, 4.73 Tg C was exportable.
机译：在近海对流过程中，在西北非洲的毛里塔尼亚上升流系统的一丝中跟踪了生物地球化学过程的拉格朗日进程。惰性对决示踪剂六氟化硫和3氦标记了刚升起的水面，标绘了8天。测量了生物，物理和化学特征的变化，包括浮游植物的生产力，氮的同化和再生。新鲜上升流的水含有较高的养分浓度（NO_3〜-= 9.0±0.1μmolL〜（-1）; PO_4〜（3-）= 0.7±0.1μmolL〜（-1）; Si = 2.7±0.1μmolL〜（-1 -1）），但与Redfield化学计量法相比（N：P = 13.9：1）的N贫乏。在大陆架上测得的最大一次生产率为0.7 mol C m〜（-2）d〜（-1），与N的43.8 nmol L〜（-1）h〜（-1）的同化率相关。 NO_3〜-，NH_4〜+的32.8 nmol L〜（-1）h〜（-1）和以硅藻和鞭毛为主的浮游植物群落。浮游植物的丰度和活动性指标随着标记水团从大陆架斜坡过渡到更深的水中而降低，这可能与混合层深度超过光穿透深度有关。到研究结束时，测得的初级生产率为0.1 mol C m〜（-2）d〜（-1），与N的同化率为3.9 nmol L〜（-1）h〜（-1）对于NO_3〜-，对于NH_4〜+和更低的养分浓度（NO_3〜-= 4.6±0.3μmolL〜（-1）; PO_4〜（3-）= 0.4±0.1μmolL〜（-1）; Si = 0.9±0.1μmolL〜（-1））。氮再生和同化同时进行； NH_4〜+在9.4-85.0 nmol L〜（-1）h〜（-1）再生; NH_4 +在0.30-8.75 nmol L〜（-1）h〜（-1）氧化NO_2〜-在25.55-81.11 nmol L〜（-1）h〜（-1）时被氧化。结果强调了再生的NH_4〜+在维持浮游植物生产力方面的重要性，并表明上升到上游的NO_3〜-池随着向近海平流而包含的NO_3〜-比例增加。通过计算该分数并将其纳入f比率公式，我们估计年区域生产量12.38 Tg C中有4.73 Tg C可出口。

著录项

  • 来源
    《Oceanographic Literature Review》 |2016年第2期|287-289|共3页
  • 作者

  • 作者单位
  • 收录信息
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号