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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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TL;DR: In this paper, total acid-soluble and dissolved Cd, Co, Cr, Cu, Ni, Pb, and Zn concentrations in the water column of a seasonally anoxic lake were measured on a monthly basis during the course of a year.
Abstract: Total acid-soluble and dissolved Cd, Co, Cr, Cu, Ni, Pb, and Zn concentrations in the water column of a seasonally anoxic lake (Lake Sammamish, Washington) were measured on a monthly basis during the course of a year. These data, in conjunction with Fe, Mn, sulfide, and nutrient data, are used to assess the biochemical processes controlling the distribution of trace metals in the lake and how the importance of these processes varies with time. Thermodynamic calculations are used to examine changes in dissolved metal speciation in the bottom waters during the year and to assess the saturation state of metal-sulfide phases. Spatial and temporal changes in the redox conditions of the bottom waters result in increases in dissolved Co and Ni concentrations, peaks in particulate Co profiles, decreases in dissolved Cu and Cr concentrations, and significant changes in dissolved metal speciation during stagnation. The rcdox-driven cycling of Fe and Mn in the hypolimnion has a dramatic effect on Co distributions, a slight effect on Ni concentrations, and virtually no effect on Cd, Cu, Cr, and Zn concentrations. Biological uptake and regeneration processes result in a correlation between Zn and silicate concentrations throughout the water column, and it appears that biological cycling may also influence the distribution of Cd. During the sulfidic phase of stagnation dissolved Cd concentrations in the bottom waters may be controlled by metal-sulfide precipitation, Cr(V1) is probably reduced to more particle-reactive Cr(II1) and removed by settling particles, and Cu(H) is most likely reduced to Cu(1) and precipitated as a metal-sulfide phase.
115 citations
TL;DR: From the preliminary Hg mass balance it appears that the Gulf is an efficient trap for total Hg and a net source of MeHg, and strong seasonal variation of sedimentation rates of particulate Hg was found during a 2-year study in the central part of the Gulf.
115 citations
TL;DR: In this article, the authors present chemostratigraphic results for iron, carbon, molybdenum, and sulfur for two outcrop sections for the ca. 663-654-Ma Datangpo Formation deposited between the two major Neoproterozoic glacial episodes (Sturtian and Marinoan) in the Nanhua Basin, South China.
115 citations
TL;DR: It is assumed that carbon flowing into the microbial loop through the mediation of enzymatic degradation of extracellular products in a benthic system exceeds that in the overlying water column.
115 citations
TL;DR: A series of lake-wide surveys carried out by as mentioned in this paper revealed that the temperature of the lake had risen by > 1 °C since 1927, with more rapid warming of the deeper waters reducing the thermal gradient in the water column and thus weakening stratification and the extent and severity of deoxygenation.
Abstract: Beginning in the mid-1980s Lake Victoria experienced severe eutrophication and it was suggested that deteriorating water quality might lead to a collapse of its fisheries. A series of lake-wide surveys carried out 1999–2001 and 2005–2009 revealed that the temperature of the lake had risen by > 1 °C since 1927, with more rapid warming of the deeper waters reducing the thermal gradient in the water column and thus weakening stratification and the extent and severity of deoxygenation. The chlorophyll a concentrations in open water decreased since the 1980s, while Secchi disc visibility increased, indicating a reduced severity of algal blooms. Chlorophyll a was higher and Secchi disc visibility lower in inshore waters but there has been no deterioration in these areas since the 1980s. The conductivity remained unchanged, although it was about 50% greater in the semi-enclosed Nyanza Gulf than in the open lake. The water quality of the lake has therefore improved considerably despite the fact than concentrations of plant nutrients have not decreased and the reasons why this may be the case are discussed. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
115 citations