The English–Wabigoon River System: II. Suppression of Mercury and Selenium Bioaccumulation by Suspended and Bottom Sediments

1983 ◽  
Vol 40 (12) ◽  
pp. 2218-2227 ◽  
Author(s):  
John W. M. Rudd ◽  
Michael A. Turner
Keyword(s):  
Bottom Sediments ◽  
Food Chain ◽  
Organic Material ◽  
Aquatic Ecosystems ◽  
Surface Sediments ◽  
River System ◽  
Fine Particulates ◽  
Mercury Bioaccumulation ◽  
Presence And Absence

Bioaccumulation of 203Hg and 75Se by several members of the food chain, including fish, was followed in large in situ enclosures in the presence and absence of organic-poor sediment. When the sediment was absent, 203Hg was bioaccumulated 8- to 16-fold faster than when it was either suspended in the water or present on the bottom of the enclosures. Mercury-contaminated and uncontaminated sediments were equally effective at reducing the rate of radiolabeled mercury bioaccumulation, apparently by binding the mercury to fine particulates making it less available for methylation and/or bioaccumulation. Based on these results, a mercury ameliorating procedure involving semicontinuous resuspension of organic-poor sediments with downstream deposition onto surface sediments is suggested. The presence of sediments, in the water or on the bottom of enclosures, also reduced radiolabeled selenium bioaccumulation. The degree of inhibition (2- to 10-fold) may have been related to the concentration of organic material in the predominantly inorganic sediments. Implications of this research with respect to mercury–selenium interactions in aquatic ecosystems are discussed.

The English–Wabigoon River System: V. Mercury and Selenium Bioaccumulation as a Function of Aquatic Primary Productivity

1983 ◽  
Vol 40 (12) ◽  
pp. 2251-2259 ◽  
Author(s):  
John W. M. Rudd ◽  
Michael A. Turner
Keyword(s):  
Growth Rate ◽  
Primary Productivity ◽  
Growth Rates ◽  
River System ◽  
Whole Body ◽  
Aquatic Food Chain ◽  
Mercury Bioaccumulation ◽  
Aquatic Food ◽  
Stimulation Of

An experiment was carried out in four 100-m3 in situ enclosures to determine the effect of primary production rate on mercury and selenium concentrations of biota and to test the possibility of ameliorating mercury pollution problems by increasing ecosystem primary productivity. Two enclosures were controls. Primary productivity in a third enclosure was increased fourfold by addition of NaNO3 and NaH2PO4. This stimulation was not sufficient to change pH although the growth rate of fish was enhanced. In this enclosure, mercury concentrations in pearl dace (Semotilus margarita) whole body and muscle samples increased two- and five-fold, respectively, exceeding the dilution of mercury by the enhanced growth rates. In the fourth enclosure, at the highest rate of nutrient addition, primary productivity was increased ninefold, pH was elevated from about 7.9 to 9.2, and the growth rate of fish was stimulated. In this case, the elevation of pH retarded the rate of mercury bioaccumulation in comparison with the enclosure of intermediate productivity. Based on these results, stimulation of primary productivity is not recommended as a mercury ameliorating procedure. Stimulation of primary productivity resulted in a general decrease in the concentration of selenium in the aquatic food chain probably resulting from dilution of selenium by enhanced growth rates of fish and other biota.

scholarly journals The ecological half-life of radiocesium in surficial bottom sediments of five ponds in Fukushima based on in situ measurements with plastic scintillation fibers

2020 ◽  
Vol 22 (7) ◽  
pp. 1566-1576
Author(s):  
Estiner Walusungu Katengeza ◽  
Yukihisa Sanada ◽  
Kazuya Yoshimura ◽  
Kotaro Ochi ◽  
Takeshi Iimoto
Keyword(s):  
Bottom Sediments ◽  
Half Life ◽  
Surface Sediments ◽  
In Situ Measurements ◽  
Plastic Scintillation

Ecological half-life (Teco) of 137Cs concentration over wide pond areas of surface sediments was evaluated from in situ monitoring with plastic scintillation fibers (PSF) between 2013 and 2019.

The English–Wabigoon River System: I. A Synthesis of Recent Research with a View towards Mercury Amelioration

1983 ◽  
Vol 40 (12) ◽  
pp. 2206-2217 ◽  
Author(s):  
John W. M. Rudd ◽  
Michael A. Turner ◽  
Akira Furutani ◽  
Alison L. Swick ◽  
B. E. Townsend
Keyword(s):  
Water Column ◽  
Surface Sediments ◽  
Selenium Concentration ◽  
River System ◽  
Surface Layers ◽  
Advantages And Disadvantages ◽  
Federal Department ◽  
Pollution Problem ◽  
Single Addition ◽  
Mercury Bioaccumulation

Over a 3-yr period, teams from the federal Department of Fisheries and Oceans, the federal Department of the Environment, and the Ontario Ministry of the Environment researched the mercury pollution problem of the English–Wabigoon River system, north-western Ontario, Canada. Mercury methylation and bioaccumulation were occurring mainly in the water column and surface layers of the sediments. Most mercury in the system was buried below the surficial sediments and probably does not contribute substantially to present mercury bioaccumulation. Movement of mercury between geochemical and biological compartments was rapid within the water column and surface sediments. Also, substantial amounts of inorganic and methyl mercury were transported down the river–lake system, having been released from stretches of river upstream of Clay Lake and deposited onto the surfaces of downstream lake sediments. Because of the constant movement of mercury into the water and onto downstream surface sediments, mercury amelioration procedures should concentrate on reducing bioaccumulation rates from both the water column and surface sediments. Treatments such as a single addition of clean clay to the surface sediments of lakes would probably be unsuccessful as long as significant downstream movement of mercury continues. Semicontinuous resuspension of bottom sediments followed by downstream deposition and/or elevation of the selenium concentration in biota by low-level additions of selenite were found to be the two most promising amelioration strategies. Both of these approaches would treat the problem in the water column and surface sediments. We consider advantages and disadvantages of these ideas and some needs for further research.

The English–Wabigoon River System: III. Selenium in Lake Enclosures: Its Geochemistry, Bioaccumulation, and Ability to Reduce Mercury Bioaccumulation

1983 ◽  
Vol 40 (12) ◽  
pp. 2228-2240 ◽  
Author(s):  
Michael A. Turner ◽  
John W. M. Rudd
Keyword(s):  
Aquatic Ecosystems ◽  
River System ◽  
Aquatic Biota ◽  
Dependent Manner ◽  
Catostomus Commersoni ◽  
Concentration Dependent Manner ◽  
Northwestern Ontario ◽  
Concomitant Reduction ◽  
Experimental Ecosystems ◽  
Mercury Bioaccumulation

Aquatic biota have been shown previously to bioaccumulate selenium rapidly with a concomitant reduction in accumulation of mercury when exposed to 100 μg Se/L. Using radioisotope techniques this experiment extends these observations by examining the effects of single additions of sodium selenite at 1, 10, and 100 μg Se/L to experimental ecosystems (130 m3) located in mercury-contaminated Clay Lake, northwestern Ontario (50°03′N, 90°30′W). The major sink for added selenium and mercury was the sediment. Movement of 75Se into the sediments in control enclosures (< 0.2 μg Se/L) appeared to stabilize within 6 wk; however, movement did not stabilize in the selenium enclosures where selenium remaining in water was largely ionic. At first, selenium accumulated rapidly in net plankton but then declined in correspondence with water concentrations. In Anadonta sp. and Orconectes virilis, selenium increased with time and in proportion to ambient selenium. Stable concentrations of selenium were not achieved in fish after 2 mo, but levels always varied according to the following sequence: Semotilus margarita < Perca flavescens < Catostomus commersoni, ranging from 0.2 to 0.4 μg Se/g (wet wt) at 1 μg Se/L. Accumulation of mercury was reduced in several biota in a concentration-dependent manner, with greatest reductions observed at 100 μg Se/L. These reductions appeared to depend on the position of the organism in the food web. In fish, the reduction was proportional to the amount of selenium accumulated. If not present in excessive amounts, selenium might be of benefit in the treatment of aquatic ecosystems with either atmospheric or point-source mercury pollution problems.

scholarly journals Mechanistic strategies of microbial communities regulating lignocellulose deconstruction in a UK salt marsh

Microbiome ◽  
2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Daniel R. Leadbeater ◽  
Nicola C. Oates ◽  
Joseph P. Bennett ◽  
Yi Li ◽  
Adam A. Dowle ◽  
...  
Keyword(s):  
Salt Marsh ◽  
Salt Marshes ◽  
Molecular Mechanisms ◽  
Surface Sediments ◽  
Gene Profiling ◽  
Oxidative Enzymes ◽  
Lignocellulose Degradation ◽  
Rrna Gene ◽  
Enzymatic Mechanisms

Abstract Background Salt marshes are major natural repositories of sequestered organic carbon with high burial rates of organic matter, produced by highly productive native flora. Accumulated carbon predominantly exists as lignocellulose which is metabolised by communities of functionally diverse microbes. However, the organisms that orchestrate this process and the enzymatic mechanisms employed that regulate the accumulation, composition and permanence of this carbon stock are not yet known. We applied meta-exo-proteome proteomics and 16S rRNA gene profiling to study lignocellulose decomposition in situ within the surface level sediments of a natural established UK salt marsh. Results Our studies revealed a community dominated by Gammaproteobacteria, Bacteroidetes and Deltaproteobacteria that drive lignocellulose degradation in the salt marsh. We identify 42 families of lignocellulolytic bacteria of which the most active secretors of carbohydrate-active enzymes were observed to be Prolixibacteracea, Flavobacteriaceae, Cellvibrionaceae, Saccharospirillaceae, Alteromonadaceae, Vibrionaceae and Cytophagaceae. These families secreted lignocellulose-active glycoside hydrolase (GH) family enzymes GH3, GH5, GH6, GH9, GH10, GH11, GH13 and GH43 that were associated with degrading Spartina biomass. While fungi were present, we did not detect a lignocellulolytic contribution from fungi which are major contributors to terrestrial lignocellulose deconstruction. Oxidative enzymes such as laccases, peroxidases and lytic polysaccharide monooxygenases that are important for lignocellulose degradation in the terrestrial environment were present but not abundant, while a notable abundance of putative esterases (such as carbohydrate esterase family 1) associated with decoupling lignin from polysaccharides in lignocellulose was observed. Conclusions Here, we identify a diverse cohort of previously undefined bacteria that drive lignocellulose degradation in the surface sediments of the salt marsh environment and describe the enzymatic mechanisms they employ to facilitate this process. Our results increase the understanding of the microbial and molecular mechanisms that underpin carbon sequestration from lignocellulose within salt marsh surface sediments in situ and provide insights into the potential enzymatic mechanisms regulating the enrichment of polyphenolics in salt marsh sediments.

Facilitated Heterogeneous Photodegradation of Dissolved Organic Matter by Particulate Iron

2004 ◽  
Vol 1 (3) ◽  
pp. 197 ◽  
Author(s):  
Julia A. Howitt ◽  
Darren S. Baldwin ◽  
Gavin N. Rees ◽  
Barry T. Hart
Keyword(s):  
Organic Matter ◽  
Iron Oxide ◽  
Dissolved Organic Matter ◽  
Iron Oxides ◽  
Aquatic Ecosystems ◽  
Photochemical Reactions ◽  
Freshwater Systems ◽  
Particulate Iron ◽  
Presence And Absence ◽  
Australian Freshwater

Environmental Context. Iron oxides, as suspended minerals or as a colloidal phase, are common in Australian freshwater systems. Freshwater systems are also loaded with carbon-based substances, ‘dissolved organic matter’, but not all is biologically available as food to freshwater organisms. However, photochemical interactions between these iron oxides and dissolved organic matter provide a mechanism for biologically resistant carbon to re-enter the food web. Suspended iron oxides thus need to be considered in carbon cycles in aquatic ecosystems. Abstract. The photochemical degradation of dissolved organic matter (DOM) derived from the leaves of River Red Gum (Eucalyptus camaldulensis) was examined, with a particular focus on the photochemical generation of CO2, consumption of O2, and the effect of particulate iron minerals on these photochemical reactions. Solutions of leaf leachate were irradiated with ultraviolet and visible light in the presence and absence of amorphous iron oxides. Addition of fresh iron oxide was found to increase the rate of photodegradation of the organic matter by up to an order of magnitude compared to the reactions without added iron oxide. The ratio of CO2 produced to O2 consumed was ~1:1 in both the presence and absence of iron oxyhydroxide. The reactivity of the iron oxides was dependent on the preparation method and decreased with increased storage time. These results suggest that photochemical reactions on particle surfaces should be considered when examining carbon transformation in aquatic ecosystems, especially at sites with potential for the production of iron oxyhydroxides.

Oxygen uptake of bottom sediments studied in situ and in the laboratory

1973 ◽  
Vol 7 (9) ◽  
pp. 1285-1294 ◽  
Author(s):  
Nils Edberg ◽  
Bengt V. Hofsten
Keyword(s):  
Oxygen Uptake ◽  
Bottom Sediments

Is it possible to determine formation processes of organic deposits through polysaccharides? Pilot study from the prehistoric site in Brandýs nad Labem, Czech Republic

The Holocene ◽  
2017 ◽  
Vol 27 (9) ◽  
pp. 1273-1280
Author(s):  
Klement Rejšek ◽  
Jan Turek ◽  
Valerie Vranová ◽  
Roman Hadacz ◽  
Lenka Lisá
Keyword(s):  
Czech Republic ◽  
Pilot Study ◽  
Organic Material ◽  
Archaeological Site ◽  
Soil Samples ◽  
Formation Processes ◽  
Cultural Layer ◽  
Different Types ◽  
Organic Deposits

This paper deals with a possible interpretation value of biochemical methods in comparison with the classic tools of geoarchaeology for the evaluation of formation processes. Organic rich layers from the archaeological site Brandýs nad Labem-Vrábí were tested with the aim to determine the origin of several different types of soil organic material by analyzing the content of different sugars. The studied soil body showed signs of cultural layer, redeposited soils, and in situ developed soil. The analysis of different sugars was highlighted: soil samples taken from these layers were analyzed to assess the ratios of mannose + galactose to arabinose + xylose, and of rhamnose + fucose to arabinose + xylose, content of Corg and different nitrates, as well as different rates of absorbance. The results show that the interpretation values of polysaccharides evaluation didn’t bring significant results itself, but in combination with classical tools of geoarchaeology may bring interpretable and new results.

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