Water column

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

Thermal Stratification in the Arctic Ocean

Abstract: Fine scale measurements of the vertical temperature profile in an Arctic water column show the presence of several cascaded isothermal layers. Layers between the depths of 300 anid 350 meters range from 2 to 10 meters in thickness, while the temperature change between adjacent layers is approximately 0.026 degrees C. The individual layers are isothermal to within +/- 0.001 degrees C.

Inorganic carbon in the Indian Ocean: Distribution and dissolution processes

Abstract: [1] This study uses nearly 25,000 carbon measurements from the WOCE/JGOFS global CO2 survey to examine the distribution of dissolved inorganic carbon (DIC) and total alkalinity (TA) in the Indian Ocean. Shallow and intermediate distributions of inorganic carbon do not strictly follow temperature and salinity because of differing surface gradients and vertical biological processes that work to modify the circulation derived features. Anthropogenic CO2 has increased the shallow DIC by as much as 3%, decreasing the vertical DIC gradient. Deep ocean DIC and TA increase toward the north because of the decomposition and dissolution of organic and inorganic particles. Calcite saturation depths range from 2900–3900 m with the deepest saturation depth in the central Indian Ocean. Variations of aragonite saturation depth (200–1400 m) are similar to calcite, but the deepest saturations are in the southwestern Indian Ocean. The shallowest aragonite saturation depths are found in the Bay of Bengal. In the northern Arabian Sea and Bay of Bengal, the current aragonite saturations are 100 and 200 m shallower, respectively, than in preindustrial times. Estimates of carbonate dissolution rates on isopycnal surfaces range from 0.017 to 0.083 μmol kg−1 yr−1 in deep waters. Upper water column dissolution rates range from 0 to 0.73 μmol kg−1 yr−1, with a local maximum occurring in intermediate waters just below the aragonite saturation horizon. Dissolution is also generally higher north of the Chemical Front at 10–20°S. There is some evidence for significant sedimentary sources in the northern Indian Ocean.

The production and fate of phytoplankton size fractions in the plume of the Hudson River, New York Bight1

Abstract: Seasonal effects of water column stability, phytoplankton growth, and copepod grazing on the biomass of phytoplankton size fractions are described in the context of variations in particulate organic carbon (POC). Net plankton biomass was more variable in time (between weeks and months), while nanoplankton biomass was more variable in space (between surface and bottom layers and between stations). Biomass was highest and most uniformly distributed during February-IMarch when net plankton diatoms dominated and doubling times approximated the flushing time of the plume. Biomass declined rapidly with depth and distance from the mouth of the estuary during June-July when nanoplankton dominated and doubling times were short relative to the flushing time of the plume. Variations in POC were well correlated with phytoplankton biomass when net plankton dominated and biomass was limited by sinking and mixing. When nanoplankton dominated, biomass was limited mainly by grazing and correlations between POC and biomass were poor. It appears that most of the biomass produced by net plankton diatoms sinks from the surface layer before the summer thermocline develops, while most of the biomass produced by nanoplankton during the summer enters pelagic food chains before sinking from the surface layer,

Planktonic marine luminous bacteria: species distribution in the water column.

Abstract: Luminous bacteria were isolated from oceanic water samples taken throughout the upper 1,000 m and ranged in density from 0.4 to 30 colony-forming units per 100 ml. Generally, two peaks in abundance were detected: one in the upper 100 m of the water column, which consisted primarily of Beneckea spp.; and a second between 250 and 1,000 m, which consisted almost entirely of Photobacterium phosphoreum. The population of P. phosphoreum remained relatively stable in abundance at one station that was visited three times over a period of 6 months. However, the abundance of luminous Beneckea spp. isolated from the upper waters fluctuated considerably; they were, as high as 30 colony-forming units per 100 ml in the spring and were not detected in the winter. Water samples from depths of 4,000 to 7,000 m contained less than 0.1 luminous colony-forming unit per 100 ml. The apparent vertical stratification of two taxa of oceanic luminous bacteria may reflect not only differences in physiology, but also depth-related, species-specific symbiotic associations.

Detritus in the Lake Ecosystem

Abstract: Present views of the roles of detritus are not consistent with the ecosystem concept, and result in an underestimation of the importance of carbon and energy pathways involving detritus. Nonpredatory losses from a plant-herbivore transfer, particularly as dissolved organic matter and egestion, may be greater than the amount of material and energy transmitted up the grazer food chain. Ecosystem efficiencies are significantly higher than Lindeman (food chain) efficiencies. Benthic anaerobic metabolism (CO2 production) is greater than benthic oxygen uptake estimates indicate, and the energy-rich intermediate products which undergo deferred respiration (O2 uptake) far from their origin may create redox gradients, drive chemosynthesis, and subsidize bacterial photosynthesis in the water column. Thus, aquatic detrital material, particulate and dissolved, and its metabolism create a dynamic structure in lake sediments and water somewhat analogous to the trophic-dynamic aspect of the biota. However, detrital-dyna...