Remobilization of trace metals induced by microbiological activities near sediment-water interface, Aha Lake, Guiyang

2003 ◽  
Vol 48 (21) ◽  
pp. 2352 ◽  
Author(s):  
Fushun WANG
Keyword(s):  
Trace Metals ◽  
Water Interface ◽  
Aha Lake

Response of diffusive equilibrium in thin films (DET) and diffusive gradients in thin films (DGT) trace metal profiles in sediments to phytodetritus mineralisation

2012 ◽  
Vol 9 (1) ◽  
pp. 41 ◽  
Author(s):  
Yue Gao ◽  
Martine Leermakers ◽  
Annelies Pede ◽  
Aurelie Magnier ◽  
Koen Sabbe ◽  
...  
Keyword(s):  
Thin Films ◽  
Trace Metals ◽  
Trace Metal ◽  
Phytoplankton Bloom ◽  
Marine Ecosystem ◽  
Trace Metal Concentration ◽  
Water Interface ◽  
Overlying Water ◽  
Study Laboratory ◽  
Diffusive Gradients

Environmental contextContaminated sediments can have a large and lasting effect on marine ecosystems. It was discovered that significant amounts of pollutants, especially arsenic, were released from contaminated sediments during a phytoplankton bloom in the Belgian Continental Zone. Once released to the water column, these pollutants can accumulate up marine food chains and be a source of contaminants to humans. AbstractField data from the Belgian Continental Zone showed elevated trace metal concentrations at the sediment–water interface after the occurrence of a phytoplankton bloom. In the present study, laboratory incubation experiments were used to investigate the effect of the phytodetritus remineralisation process on the release of trace metals from contaminated muddy sediments. This remineralisation process was followed by the measurement of chlorophyll-a and dissolved organic carbon levels in the top sediment layers. Two gel techniques, diffusive equilibrium in thin films (DET) and diffusive gradients in thin films (DGT), were used to assess vertical metal profiles in the sediment pore waters and to calculate the metal effluxes. These metal effluxes compared very well with the trace metal concentration variations in the overlying water of the sediment. Much higher effluxes of Mn, Co and As were observed after 2 days of incubation in the microcosms which received additions of phytodetritus. This trend gradually decreased after 7 days of incubation, suggesting that the elevated efflux of trace metals was proportional to the quantity of phytodetritus mineralised at the sediment–water interface. The release of large amounts of toxic elements from the sediments after phytoplankton blooms can therefore potentially affect the marine ecosystem in the Belgian Continental Zone.

scholarly journals Two Approaches to Measure Trace Metals Fluxes at Sediment-Water Interface: Sediment Porewater Profile and Benthic Incubation

2020 ◽  
Vol 37 (3) ◽  
Author(s):  
Harmesa ◽  
A’an Johan Wahyudi
Keyword(s):  
Trace Metals ◽  
Biogeochemical Cycle ◽  
Physical Factors ◽  
Water Interface ◽  
Overlying Water ◽  
Main Challenge ◽  
Potential Impact ◽  
Incubation Method ◽  
Coefficient Of Diffusion

The biogeochemical cycle of trace metals is very likely affected by the global change in the ocean, especially due to the increasing of sea surface temperature and acidity. Thus, assessing biogeochemical cycle of trace metals will beneficial in elucidating the potential impact of climate change as well as ocean acidification. The assessment of the biogeochemical cycle of trace metals can be performed by measuring trace metals fluxes crossing the sediment-water interface. The main challenge in this measurement is the difficulty of measuring metal concentrations at trace levels due to either physical factors or biological factors that can affect the total flux. Sediment porewater profile and in situ benthic incubation are the two most commonly used methods for measuring trace metals fluxes from sediment to the overlying water or vice versa. The coefficient of diffusion and gradient of concentration are the two most important values in the sediment porewater profile method, while the constant volume involved in the container during the experiment is an important part of the in situ benthic incubation method. The purpose of this review is to provide an overview of both measurement methods deeply and predict the challenges faced in its implementation in Indonesia. Keywords: Benthic fluxes; Overlying water; Porewater; Sediment; Trace metals

Techniques for Imaging Internal Composition and Structure of MN Micronodules

1980 ◽  
Vol 38 ◽  
pp. 198-199
Author(s):  
Leo A. Barnard
Keyword(s):  
Trace Metals ◽  
Marine Sediments ◽  
Manganese Nodule ◽  
Economic Importance ◽  
Water Interface ◽  
Composition And Structure

Manganese micronodules (Mn accumulations <500 μm diameter found throughout marine sediments) represent as much as 65-80% of all marine sedimentary Mn (Chester and Hughes, 1969). Work on marine manganese occurrences up to the present time has been focused upon nodules (> 1 cm diameter) found at the sediment-water interface. The economic importance of nodule associated trace metals explains this restricted approach but does not aid our understanding of the genetic processes for manganese accumulation. Micronodules have not been studied with the rigor due a potential manganese nodule precursor species.

scholarly journals The control of hydrogen sulfide on benthic iron and cadmium fluxes in the oxygen minimum zone off Peru

2020 ◽  
Vol 17 (13) ◽  
pp. 3685-3704
Author(s):  
Anna Plass ◽  
Christian Schlosser ◽  
Stefan Sommer ◽  
Andrew W. Dale ◽  
Eric P. Achterberg ◽  
...  
Keyword(s):  
Trace Metals ◽  
Trace Metal ◽  
Pore Water ◽  
Bottom Water ◽  
Oxygen Minimum Zone ◽  
Water Interface ◽  
Benthic Chamber ◽  
Minimum Zone ◽  
Cd Removal ◽  
Oxygen Minimum

Abstract. Sediments in oxygen-depleted marine environments can be an important sink or source of bio-essential trace metals in the ocean. However, the key mechanisms controlling the release from or burial of trace metals in sediments are not exactly understood. Here, we investigate the benthic biogeochemical cycling of iron (Fe) and cadmium (Cd) in the oxygen minimum zone off Peru. We combine bottom water and pore water concentrations, as well as benthic fluxes determined from pore water profiles and from in situ benthic chamber incubations, along a depth transect at 12∘ S. In agreement with previous studies, both concentration–depth profiles and in situ benthic fluxes indicate a release of Fe from sediments to the bottom water. Diffusive Fe fluxes and Fe fluxes from benthic chamber incubations (−0.3 to −17.5 mmol m−2 yr−1) are broadly consistent at stations within the oxygen minimum zone, where the flux magnitude is highest, indicating that diffusion is the main transport mechanism of dissolved Fe across the sediment–water interface. The occurrence of mats of sulfur-oxidizing bacteria on the seafloor represents an important control on the spatial distribution of Fe fluxes by regulating hydrogen sulfide (H2S) concentrations and, potentially, Fe sulfide precipitation within the surface sediment. Rapid removal of dissolved Fe after its release to anoxic bottom waters hints at oxidative removal by nitrite and interactions with particles in the near-bottom water column. Benthic flux estimates of Cd suggest a flux into the sediment within the oxygen minimum zone. Fluxes from benthic chamber incubations (up to 22.6 µmol m−2 yr−1) exceed diffusive fluxes (<1 µmol m−2 yr−1) by a factor of more than 25, indicating that downward diffusion of Cd across the sediment–water interface is of subordinate importance for Cd removal from benthic chambers. As Cd removal in benthic chambers covaries with H2S concentrations in the pore water of surface sediments, we argue that Cd removal is mediated by precipitation of cadmium sulfide (CdS) within the chamber water or directly at the sediment–water interface. A mass balance approach, taking the contributions of diffusive and chamber fluxes as well as Cd delivery with organic material into account, suggests that CdS precipitation in the near-bottom water could make an important contribution to the overall Cd mass accumulation in the sediment solid phase. According to our results, the solubility of trace metal sulfide minerals (Cd ≪ Fe) is a key factor controlling trace metal removal and, consequently, the magnitude and the temporal and spatial heterogeneity of sedimentary fluxes. We argue that, depending on their sulfide solubility, sedimentary source or sink fluxes of trace metals will change differentially as a result of declining oxygen concentrations and the associated expansion of sulfidic surface sediments. Such a trend could cause a change in the trace metal stoichiometry of upwelling water masses with potential consequences for marine ecosystems in the surface ocean.

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