Transfer of Contaminants between the Water Column and Bottom Sediments: The Role of Deposit-and Suspension-Feeding Benthic Invertebrates.

1998 ◽  
Author(s):  
Cheryl A. Butman ◽  
Robert A. Wheatcroft
Keyword(s):  
Water Column ◽  
Bottom Sediments ◽  
Benthic Invertebrates ◽  
Suspension Feeding

Methylmercury biogeochemistry: a review with special reference to Arctic aquatic ecosystems

2014 ◽  
Vol 22 (3) ◽  
pp. 229-243 ◽  
Author(s):  
Igor Lehnherr
Keyword(s):  
Food Webs ◽  
Water Column ◽  
Human Health ◽  
Bottom Sediments ◽  
Aquatic Ecosystems ◽  
Marine Mammals ◽  
Primary Source ◽  
The Arctic ◽  
Arctic Biota

There has been increasing concern about mercury (Hg) levels in marine and freshwater organisms in the Arctic, due to the importance of traditional country foods such as fish and marine mammals to the diet of Northern Peoples. Due to its toxicity and ability to bioaccumulate and biomagnify in food webs, methylmercury (MeHg) is the form of Hg that is of greatest concern. The main sources of MeHg to Arctic aquatic ecosystems, the processes responsible for MeHg formation and degradation in the environment, MeHg bioaccumulation in Arctic biota and the human health implications for Northern Peoples are reviewed here. In Arctic marine ecosystems, Hg(II) methylation in the water column, rather than bottom sediments, is the primary source of MeHg, although a more quantitative understanding of the role of dimethylmercury (DMHg) as a MeHg source is needed. Because MeHg production in marine waters is limited by the availability of Hg(II), predicted increases in Hg(II) concentrations in oceans are likely to result in higher MeHg concentrations and increased exposure to Hg in humans and wildlife. In Arctic freshwaters, MeHg concentrations are a function of two antagonistic processes, net Hg(II) methylation in bottom sediments of ponds and lakes and MeHg photodemethylation in the water column. Hg(II) methylation is controlled by microbial activity and Hg(II) bioavailability, which in turn depend on interacting environmental factors (temperature, redox conditions, organic carbon, and sulfate) that induce nonlinear responses in MeHg production. Methylmercury bioaccumulation–biomagnification in Arctic aquatic food webs is a function of the MeHg reservoir in abiotic compartments, as well as ecological considerations such as food-chain length, growth rates, life-history characteristics, feeding behavior, and trophic interactions. Methylmercury concentrations in Arctic biota have increased significantly since the onset of the industrial age, and in some populations of fish, seabirds, and marine mammals toxicological thresholds are being exceeded. Due to the complex connection between Hg exposure and human health in Northern Peoples—arising from the dual role of country foods as both a potential Hg source and a nutritious, affordable food source with many physical and social health benefits—-reductions in anthropogenic Hg emissions are seen as the only viable long-term solution.

scholarly journals Evaluation of sedimentation role of DREISSENA molluscs' population in the process of water quality control in Kakhovka Main Channel (Kherson Region)

2021 ◽  
pp. 76-85
Author(s):  
D. V. Lukashov ◽  
L. K. Khokhlova
Keyword(s):  
Water Quality ◽  
Water Column ◽  
Bottom Sediments ◽  
Irrigation Water ◽  
Suspended Matter ◽  
Agricultural Land ◽  
Main Channel ◽  
Artificial Substrates ◽  
Bivalve Molluscs

Ukraine has a unique natural resources potential and is one of the world's richest agricultural countries in terms of soil composition and land bioproductivity. More than 2/5 of its agricultural land is located within the steppe zone – a zone of unstable and insufficient humidification. The production of agricultural products under arid conditions largely depends on solving the problem of agricultural land artificial irrigation. Due to this, since the 1960s large-scale construction of amelioration facilities took place in Southern Ukraine, including construction of the Kakhovka Reservoir and the Kakhovka Irrigation System, the largest one in Europe. The quality of water intended for irrigation depends on a water source and internal physicochemical/biological processes observed in the amelioration system. The attached bivalve molluscs present an important biotic component of hydrotechnical amelioration systems. They form dense settlements on solid artificial substrates and are usually considered as a source of biological barriers that should be constantly fought against. However, their filtration and sedimentation role can exert influence on the processes of water self-purification. The study aims at evaluating the role of filtering molluscs fouling process when it comes to treatment of irrigation water from suspensions and removal of some heavy metals from the water column. The research is based on the results of field analysis of deposits sedimentation processes in the water column with the help of sedimentation traps at 5 stations along Kakhovka Main Channel. It was found that the total biomass of settlements of attached bivalve molluscs Dreissena polymorpha and Dreissena bugensis that are present in the channel constitutes about 370 – 463 tons and they contribute to precipitation of 11.6 – 27.5 tons of suspended matter to the bottom sediments during summer months. This process is manifested in a decrease of suspended matter concentration in the water along the channel. Together with suspended matter 1.8 – 3.9 kg of Cr, 0.3 – 0.6 kg of Ni, 0.09 – 0.24 kg of Co, 0.08 – 0.18 kg of Pb, 0.088 – 0,144 kg of Cd also join the bottom sediments every month. Thus, the settlements of molluscs attached to the hydraulic structures can be considered as biological amelioration agents contributing to the improvement of irrigation water quality.

Sedimentation of Pb-210 in Laurentian Shield Lakes

1984 ◽  
Vol 19 (2) ◽  
pp. 97-109 ◽  
Author(s):  
R.J. Cornett ◽  
L. Chant ◽  
D. Link
Keyword(s):  
Lake Sediments ◽  
Water Column ◽  
Rate Constant ◽  
Bottom Sediments ◽  
Atmospheric Fallout ◽  
Small Lakes ◽  
Fractional Rate ◽  
Total Input ◽  
Shield Lakes ◽  
Annual Flux

Abstract The average annual flux of Pb-210 from the atmosphere to lake surfaces and to the bottom sediments was measured in seven small lakes located on the Laurentian Shield. Direct atmospheric fallout of Pb-210 was 136 ± 16 Bq m-2 a-1 Streams from the lakes' catchments input an additional 5 to 473 Bq m-2 a-1. Only 16 to 80 percent of the total input was found in the lake sediments. The fractional rate constant for Pb-210 sedimentation from the water column ranged from 0.25 to 5.3 per annum.

Seasonal variations of water column nutrients in the inner area of Ariake Bay, Japan: the role of muddy sediments

2013 ◽  
Vol 185 (8) ◽  
pp. 6831-6846 ◽  
Author(s):  
Masumi Koriyama ◽  
Yuichi Hayami ◽  
Akane Koga ◽  
Koichi Yamamoto ◽  
Alim Isnasetyo ◽  
...  
Keyword(s):  
Water Column ◽  
Seasonal Variations ◽  
Ariake Bay ◽  
Muddy Sediments

Effects of Fe addition on sediment P dynamics in a eutrophic lake

2021 ◽  
Author(s):  
Melanie Münch ◽  
Rianne van Kaam ◽  
Karel As ◽  
Stefan Peiffer ◽  
Gerard ter Heerdt ◽  
...  
Keyword(s):  
Water Quality ◽  
Organic Matter ◽  
Surface Water ◽  
Water Column ◽  
Sediment Cores ◽  
Surface Water Quality ◽  
Water Interface ◽  
Eutrophic Lakes ◽  
Fe Addition

<p>The decline of surface water quality due to excess phosphorus (P) input is a global problem of increasing urgency. Finding sustainable measures to restore the surface water quality of eutrophic lakes with respect to P, other than by decreasing P inputs, remains a challenge. The addition of iron (Fe) salts has been shown to be effective in removing dissolved phosphate from the water column of eutrophic lakes. However, the resulting changes in biogeochemical processes in sediments as well as the long-term effects of Fe additions on P dynamics in both sediments and the water column are not well understood.</p><p>In this study, we assess the impact of past Fe additions on the sediment P biogeochemistry of Lake Terra Nova, a well-mixed shallow peat lake in the Netherlands. The Fe-treatment in 2010 efficiently reduced P release from the sediments to the surface waters for 6 years. Since then, the internal sediment P source in the lake has been increasing again with a growing trend over the years.</p><p>In 2020, we sampled sediments at three locations in Terra Nova, of which one received two times more Fe during treatment than the other two. Sediment cores from all sites were sectioned under oxygen-free conditions. Both the porewaters and sediments were analysed for their chemical composition, with sequential extractions providing insight into the sediment forms of P and Fe. Additional sediment cores were incubated under oxic and anoxic conditions and the respective fluxes of P and Fe across the sediment water interface were measured.</p><p>The results suggest that Fe and P dynamics in the lake sediments are strongly coupled. We also find that the P dynamics are sensitive to the amount of Fe supplied, even though enhanced burial of P in the sediment was not detected. The results of the sequential extraction procedure for P, which distinguishes P associated with humic acids and Fe oxides, as well as reduced flux of Fe(II) across the sediment water interface in the anoxic incubations, suggest a major role of organic matter in the interaction of Fe and P in these sediments.</p><p>Further research will include investigations of the role of organic matter and sulphur in determining the success of Fe-treatment in sequestering P in lake sediments. Based on these data in combination with reactive transport modelling we aim to constrain conditions for successful lake restoration through Fe addition.</p>

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