文章基本信息

标题：Suspension settling effect on macrobenthos biomass distribution in the Hornsund fjord, Spitsbergen
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作者：Krzysztof Görlich ; Jan M. Węslawski ; Marek Zajączkowski 等
期刊名称：Polar Research
印刷版ISSN：1751-8369
出版年度：1987
卷号：5
期号：2
页码：175-192
DOI：10.3402/polar.v5i2.6875
语种：English
出版社：Co-Action Publishing
摘要：Seasonal variations and spatial distribution of suspension composition and concentration were determined in the Hornsund fjord on south Spitsbergen along with bottom sediment mineralogy and glacial-marine mud accumulation rates. These data were related to macrobenthos biomass distribution, as well as geochemical and hydrognphic data. The axial distribution of sediment accumulation rates follows exponential decay. Slopes of the seaward decay are different for individual meltwater sources in Hornsund and, in general, they are higher than in river-fed fjords. Intensity of suspension settling is enhanced by strong retardation of meltwater flow and turbulence within the shear layer of meltwater jet sliding over strongly saline water. The most intensive settling, controlling the overall efficiency of mud deposition (up to 35 cm/a) occurs in the ice-proximal jet zone of meltwater plume. It results from turbulent diffusion of dense suspension (>1, 000 mg/1) to the underlying still-water layer. Within the more distal, slow-advection zone the sediment accumulation rate falls below 1 cm/a. Suspension is deposited here mostly due to slow settling of mature floes across the halocline. This bipartite lateral zonation results in (1) clay-mineral segregation observed in bottom mud in the ice-proximal jet zone (2M, large-flake muscovite is separated from lMd clay-grade illite), and (2) high accumulation rate and extremely rapid decay away from the source. High concentration of surface-active clays in the rapidly accumulating sediment renders the proximal mud a closed system and a physical trap for nutrients. The seasonal rhythm of changes in suspension composition reveals a time lag between maximum of organic suspension concentration and onset of clastic sedimentation. This lag along with the absolute dominance of clastic flux during summer-autumn, result in sulphidic (dark-light) lamination of ice-proximal mud. High clastic input and high surface water turbidity result in formation of a benthos-poor zone in the ice-proximal settings. There, formation and preservation of original monosulphidic lamination and scarcity of benthic life are mutually dependent. Control over these follows by damping of primary production in the photic zone and trapping of nutrients in the bottom sediment by clastic dilution and fast burial of organic material.