Nutrient mineralization patterns in shelf waters of the Western Iberian upwelling
Nutrient mineralization patterns in shelf waters of the Western Iberian upwelling
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DOI：
10.1016/s0278-4343(97)00014-9
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发表时间：
1997-08-01
影响因子：
2.3
通讯作者：
Fraga, F
中科院分区：
文献类型：
--
作者：
AlvarezSalgado, XA;Castro, CG;Fraga, F
一套水文数据收集在几次巡航西北伊比利亚上升流系统已被用来评估营养矿化的模式在大陆架。下层水柱中的矿化营养物比率（N/P和N/Si）明显低于新涌上涌的海洋沃茨的比率特征。氮矿化：与磷的矿化相比，是不完全的，与磷酸盐的更快的再生速率和水的低停留时间一致，这排除了完全矿化。硅酸盐显示出最高的富集作为一个结果的颗粒生物硅的选择性浓度在近底层沃茨。沉积物中矿化的营养物质的扩散似乎是一个重要的贡献。调查区矿化度最低的是Cape Finisterre北部，特别是硅酸盐。在南部，Rias Baixas（四个大海湾）作为减少颗粒有机物（POM）的一小部分从大陆架进口的营养物质。然而，流出的淡水有助于沿海沃茨的分层，这有利于POM的生产，积累和沉积。此外，流出物中高水平的新溶解有机物（DOM）也可以提高陆架表面沃茨的初级生产力。最后，米诺河以南发现了最高的矿化，那里没有海湾，大陆架更宽。矿化倾向于：（1）使该生态系统的潜在初级生产力增加高达50%（氮限制）或高达80%（硅限制）;（2）有利于以硅藻为主的浮游植物群落的发育（硅富集度是N和P的两倍）;和（3）缓冲平流营养物质引入的巨大空间和时间差异。(C)1997 Elsevier Science Ltd.
A set of hydrographic data collected during several cruises to the NW Iberian upwelling system has been used to assess the patterns of nutrient mineralization over the shelf. Mineralized nutrient ratios (N/P and N/Si) in the lower water column are clearly below the ratios characteristic of freshly upwelled oceanic waters. Nitrogen mineralization: in comparison to phosphorus mineralization, is incomplete, in agreement with phosphate's faster regeneration rate and the low residence time of water, which precludes complete mineralization. Silicate shows the highest enrichment as a consequence of the selective concentration of particulate biogenic silica in the near bottom waters. Diffusion of nutrients mineralized in the sediments seems to represent an important contribution. The lowest mineralization of the surveyed area is found to the north of Cape Finisterre, especially with regard to silicate. To the South, the Rias Baixas (four large embayments) return as reducing particulate organic matter (POM) a small fraction of the upwelled nutrients imported from the shelf. However, the out-flowing freshwater contributes to stratification of coastal waters, which favours POM production, accumulation and sedimentation. In addition, high levels of new dissolved organic matter (DOM) in the outflow can also enhance primary production in shelf surface waters. Finally, highest mineralization was found to the south of the River Mino, where there are no embayments and the shelf is wider. Mineralization tends to: (1) increase the potential primary production of this ecosystem by up to 50%, (nitrogen limitation) or up to 80% (silicon limitation); (2) favour the development of phytoplankton assemblages dominated by diatoms (Si enrichment double that of N and P); and (3) buffer the large spatial and temporal differences introduced by the advected nutrients. (C) 1997 Elsevier Science Ltd.