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Water column

About: Water column is a research topic. Over the lifetime, 13706 publications have been published within this topic receiving 496626 citations.


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Journal ArticleDOI
TL;DR: Analysis of material collected in settlement traps at regular intervals over a period of a year gave an estimate of the annual organic input to the bottom sediment of about 28 gC/m2 year, which is a little less than one third of the primary production in the overlying water column.
Abstract: Analysis of material collected in settlement traps at regular intervals over a period of a year gave an estimate of the annual organic input to the bottom sediment of about 28 gC/m2 year, which is a little less than one third of the primary production in the overlying water column. The aerobic benthic community metabolism, estimated from in situ respiration measurements, was not significantly different from the carbon input. The rate of release of ammonia from the sediment was also measured in situ and would be sufficient to supply the greater part of the required input of inorganic nitrogen for photosynthesis in the water column.

145 citations

Journal ArticleDOI
TL;DR: How wind-driven variability in the hydrography is translated into pulses of primary and secondary production of the plankton is studied to understand how upwelling-generated pulses of phytoplankton production are utilized by herbivorous plankton in the nearshore zone.

145 citations

Journal ArticleDOI
TL;DR: The total concentration and redox state of iron were examined along a transect across the continental shelf off the Peruvian coast during. January 1984 as discussed by the authors, where the total and dissolved iron (0.4~pm filter) were measured by the Co-APDC coprecipitation method.
Abstract: The total concentration and redox state of iron were examined along a transect across the continental shelf off the Peruvian coast during. January 1984. Total and dissolved iron (0.4~pm filter) were measured by the Co-APDC coprecipitation method. Fe(II) was measured by a preconcentration step with S-hydroxyquinoline bonded to silica as the stationary phase, followed by elution and the ferrozine method. Up to 40 nmol kg-l of Fe(II) was detected in the bottom water at 5-10 km offshore and decreased markedly upward in the water column and with distance offshore. A good correlation between the distribution of Fe(II) and nitrite in the bottom water indicated a common source from the shelf sediments. Elevated Fe(II) concentrations near the sea surface and a diel change were probably due to photochemical reactions involving iron. Total iron levels were >300-500 nmol kg-’ in the surface and the bottom water at 5-6 km offshore. About 80-90% of the iron was in the particulate form, indicating a substantial input of iron from continental dust and from the sediments on the shelf. The total iron level decreased considerably within 35 km of the coastline and the iron seemed to be trapped on the shelf. Iron is found in natural waters in both Fe(II) and Fe(III) oxidation states. The distribution of these two forms of iron is governed by several factors, including redox potential, pH, and the presence of organic material. From thermodynamic considerations, the concentration of reduced forms of iron in oxic natural waters will be much lower than that of the oxidized forms of iron due to the rapid oxidation of Fe(II) by Oz. Nevertheless, it has been suggested that nonequilibrium processes may enable Fe(II) species to persist at appreciable concentrations in natural waters even in the presence of oxygen. McMahon (1969) suggested that annual and diurnal variations of acid-soluble ferrous iron in lake water were a result of photochemical reactions or of metabolic activity of microorganisms. Recently, the photochemistry of iron in natural waters has been emphasized by several studies as reviewed by Zafiriou ( 1983). Miles and Brezonik (198 1) showed that the oxygen consumption in humic-colored freshwaters involved a photochemical ferrous-ferric catalytic cycle. Waite and Morel (1984)

145 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present a compilation of measurements of primary production, water column export flux and sediment accumulation of organic carbon over a full annual monsoon cycle on a 1500-km transect from the coast of Oman toward the central Arabian Sea.
Abstract: Organic carbon fluxes in the Arabian Sea were measured as a function of depth, season and distance from the coast of Oman. We present here a compilation of measurements of primary production, water-column export flux and sediment accumulation of organic carbon over a full annual monsoon cycle on a 1500-km transect from the coast of Oman toward the central Arabian Sea. This represents an integration of measurements spanning one day (primary production) to 1000 yr (sediments) and gives a broad overview of organic carbon removal and remineralization in the highly productive, seasonally varying region of the northern Indian Ocean. Organic carbon fluxes decreased from the surface to the sediments by a factor of 500–10,000, with the largest rates of change in the upper ocean and at the sediment–seawater interface. Organic carbon fluxes generally decreased with distance offshore, with the largest gradient between surface and seafloor being at the offshore station. Sediment accumulation rates of organic carbon differed by a factor of 40 between nearshore and offshore, while primary productivity varied only by a factor of 2. The decrease in carbon flux with depth that occurs between the deepest traps and the sediment becomes a greater proportion of the total loss with increasing distance from shore. Thus, the influence of processes at the sediment–water interface on the proportion of primary productivity preserved in the sediment increases offshore relative to upper water column processes. Carbon fluxes changed greatly with season, with highest fluxes during the Southwest Monsoon. Export fluxes varied more with season than primary productivity or mid-water fluxes.

145 citations

Journal ArticleDOI
01 Aug 1985-Nature
TL;DR: In this article, the vertical distribution and inter-ocean fractionation of aluminium can be explained by geographical variations in atmospheric aluminium sources, intense particle scavenging throughout the water column, and some regeneration in bottom waters.
Abstract: Aluminium is the most abundant metallic element in the Earth's crust (8.23% by weight)1, yet little is known about its oceanic distribution. Published data sets concerning aluminium in sea-water2 are primarily for the North Atlantic Ocean3–7. We report here that dissolved aluminium concentrations in the central North Pacific are 8–40 times lower than those at corresponding depths in the central North Atlantic, but the vertical distribution features are similar. The vertical distribution and inter-ocean fractionation of aluminium can be explained by geographical variations in atmospheric aluminium sources, intense particle scavenging throughout the water column, and some regeneration in bottom waters. Aluminium's short oceanic residence time (estimated here as 100–200 years) leads to its marked inter-ocean fractionation, which is the reverse of that for nutrient elements such as silicon.

145 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023458
2022969
2021497
2020502
2019502
2018466