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.

Dynamics of Selenium in Mercury-Contaminated Experimental Freshwater Ecosystems

1980 ◽  
Vol 37 (5) ◽  
pp. 848-857 ◽  
Author(s):  
John W. M. Rudd ◽  
Michael A. Turner ◽  
Bruce E. Townsend ◽  
Alison Swick ◽  
Akira Furutani
Keyword(s):  
Water Column ◽  
Aquatic Organisms ◽  
Selenium Concentration ◽  
Freshwater Ecosystems ◽  
Aquatic Herbicides ◽  
Mercury Bioaccumulation ◽  
Simultaneous Movement ◽  
Experimental Treatments ◽  
Aquatic Herbicide ◽  
Rate Of Movement

The simultaneous movement of radiolabeled selenium and mercury was followed in experimental aquatic ecosystems ([Formula: see text] tube enclosures) set into a mercury-contaminated lake. The experimental treatments consisted of increasing stable selenium or sulfate water concentrations, addition of an aquatic herbicide, and isolation of a portion of the water column from contact with sediments. Selenium and mercury did not move together through the ecosystems either geochemically or biologically. Selenium bioaccumulation was rapid by fish, crayfish, and haptobenthos and was enhanced by increased sulfate concentration and in the absence of exposure to bottom sediments. It was reduced in the presence of aquatic herbicides. A selenium concentration of 0.1 mg/L did not affect the rate of movement of mercury out of the water column but it did stabilize the movement of mercury among various compartments in the water column. Elevated selenium appeared to retard the rate of mercury bioaccumulation by fish, crayfish, and haptobenthos. Preliminary observations of selenium toxicity to several aquatic organisms were carried out. The possibility of using selenium as an ameliorating agent for heavy metal polluted freshwater systems is discussed.Key words: selenium, mercury, methylmercury, fish, crayfish

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.

scholarly journals Short-term variability in the sedimentary BIT index of Lake Challa, East Africa over the past 2200 years: validating the precipitation proxy

2015 ◽  
Vol 11 (2) ◽  
pp. 1177-1218 ◽  
Author(s):  
L. K. Buckles ◽  
J. W. H. Weijers ◽  
D. Verschuren ◽  
C. Cocquyt ◽  
J. S. Sinninghe Damsté
Keyword(s):  
Soil Erosion ◽  
Water Column ◽  
Surface Sediments ◽  
Austral Summer ◽  
Primary Source ◽  
Monsoon Precipitation ◽  
The Past ◽  
Rain Season ◽  
Index Variation ◽  
Large Diatom

Abstract. The branched vs. isoprenoid index of tetraethers (BIT index) in Lake Challa sediments has been applied as a monsoon precipitation proxy on the assumption that the primary source of branched tetraether lipids (brGDGTs) was soil washed in from the lake's catchment. However, water column production has since been identified as the primary source of brGDGTs in Lake Challa, meaning that there is no longer a clear mechanism linking BIT index variation and precipitation. Here we investigate BIT index variation and GDGT concentrations at a decadal resolution over the past 2200 years, in combination with GDGT data from profundal surface sediments and 45 months of sediment-trap deployment. The 2200 year record reveals high-frequency variability in GDGT concentrations, and therefore the BIT index. Also surface sediments collected in January 2010 show a distinct shift in GDGT composition relative to those collected in August 2007. Increased bulk flux of settling particles with high Ti / Al ratios during March–April 2008 reflect an event of high detrital input to Lake Challa, concurrent with intense precipitation at the onset of the principal rain season that year. Although brGDGT distributions in the settling material are initially unaffected, this soil erosion event is succeeded by a large diatom bloom in July–August 2008 and a concurrent increase in GDGT-0 fluxes. Near-zero crenarchaeol fluxes indicate that no thaumarchaeotal bloom developed during the subsequent austral summer season; instead a peak in brGDGT fluxes is observed in December 2008. We suggest that increased nutrient availability, derived from eroded soil washed into the lake, stimulated both diatom productivity and the GDGT-0 producing archaea which help decompose dead diatoms passing through the suboxic zone of the water column. This disadvantaged the Thaumarchaeota that normally prosper during the following austral summer. Instead, a bloom of supposedly heterotrophic brGDGT-producing bacteria occurred. Episodic recurrence of such high soil-erosion events, integrated over multi-decadal and longer timescales and possibly enhanced by other mechanisms generating low BIT index values in dry years, can explain the positive relationship between the sedimentary BIT index and monsoon precipitation at Lake Challa. However, application elsewhere requires ascertaining the local situation of lacustrine brGDGT production and of variables affecting the productivity of Thaumarchaeota.

scholarly journals Seasonal and interannual variability of sedimentation and organic matter distribution in the Buor-Khaya Gulf: the primary recipient of input from Lena River and coastal erosion in the southeast Laptev Sea

2011 ◽  
Vol 8 (9) ◽  
pp. 2581-2594 ◽  
Author(s):  
A. N. Charkin ◽  
O. V. Dudarev ◽  
I. P. Semiletov ◽  
A. V. Kruhmalev ◽  
J. E. Vonk ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Water Column ◽  
Surface Sediments ◽  
Organic Carbon Content ◽  
Lena River ◽  
Siberian Arctic ◽  
Sedimentation Regime ◽  
Ice Complex

Abstract. Climate warming is amplified in the land-sea system of the East Siberian Arctic, which also holds large pools of vulnerable carbon in permafrost. This coastal area is strongly influenced by sediment and carbon transport from both its large rivers and extensive erosion of Pleistocene permafrost along its coastline. This study is investigating the coastal fate of the sediment and organic carbon delivered to the Buor-Khaya Gulf, which is the first recipient of the overwhelming fluvial discharge from the Lena River and is additionally receiving large input from extensive erosion of the coastal ice-complex (permafrost a.k.a. Yedoma; loess soil with high organic carbon content). Both water column suspended particulate matter (SPM) and surface sediments were sampled at about 250 oceanographic stations in the Gulf in this multi-year effort, including one winter campaign, and analyzed for the distribution and sorting of sediment size, organic carbon content, and stable carbon isotope signals. The composition of the surface sediment suggests an overwhelmingly terrestrial contribution from both river and coastal erosion. The objective of this paper is to improve our understanding of the seasonal (i.e., winter vs summer) and interannual variability of these coastal sedimentation processes and the dynamics of organic carbon (OC) distribution in both the water column SPM and the surface sediments of the Buor-Khaya Gulf. Based on data collected during several years in the period 2000–2008, two different sedimentation regimes were revealed for the Buor-Khaya Gulf, the relative importance of each at a given time depend on hydrometeorological conditions, the Lena River water discharge and sea-ice regime: Type 1 erosion-accumulation and Type 2 accumulation. The Type 1 erosion-accumulation sedimentation regime is typical (2000–2006) for the ice-free period of the year (here considered in detail for August 2005). Under such conditions terrigenous sources of SPM and particulate organic carbon (POC) stem predominantly from river discharge, thermal erosion of coastal ice-complex and remobilized bottom sediments. The Type 2 accumulation sedimentation regime develops under ice-covered conditions, and only occasionally during the ice-free period (August 2008). In Type 2 winter, combined terrigenous and marine-biogenic SPM and POC sources are dominating due to relatively low overall terrigenous input (April 2007). In Type 2 summer, river alluvium becomes the major SPM and POC source (August 2008). The water column SPM and POC loadings vary by more than a factor of two between the two regimes. This study underscores the necessity of multi-year investigations to better understand the functioning of the primary recipient of terrestrially expulsed matter in the East Siberian Arctic.

scholarly journals Antioxidant Molecules from Plant Waste: Extraction Techniques and Biological Properties

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1566
Author(s):  
Cynthia E. Lizárraga-Velázquez ◽  
Nayely Leyva-López ◽  
Crisantema Hernández ◽  
Erick Paul Gutiérrez-Grijalva ◽  
Jesús A. Salazar-Leyva ◽  
...  
Keyword(s):  
Antibacterial Properties ◽  
Biological Properties ◽  
Antioxidant Compounds ◽  
Green Technologies ◽  
Advantages And Disadvantages ◽  
Pollution Problem ◽  
Plant Waste ◽  
Potential Applications ◽  
Environmental Pollution Problem ◽  
Pharmaceutical Industries

The fruit, vegetable, legume, and cereal industries generate many wastes, representing an environmental pollution problem. However, these wastes are a rich source of antioxidant molecules such as terpenes, phenolic compounds, phytosterols, and bioactive peptides with potential applications mainly in the food and pharmaceutical industries, and they exhibit multiple biological properties including antidiabetic, anti-obesity, antihypertensive, anticancer, and antibacterial properties. The aforementioned has increased studies on the recovery of antioxidant compounds using green technologies to value plant waste, since they represent more efficient and sustainable processes. In this review, the main antioxidant molecules from plants are briefly described and the advantages and disadvantages of the use of conventional and green extraction technologies used for the recovery and optimization of the yield of antioxidant naturals are detailed; finally, recent studies on biological properties of antioxidant molecules extracted from plant waste are presented here.

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 Contrasting vertical distributions of recent planktic foraminifera off Indonesia during the southeast monsoon: implications for paleoceanographic reconstructions

2022 ◽  
Author(s):  
Raúl Tapia ◽  
Sze Ling Ho ◽  
Hui-Yu Wang ◽  
Jeroen Groeneveld ◽  
Mahyar Mohtadi
Keyword(s):  
Vertical Distribution ◽  
Water Column ◽  
Surface Sediments ◽  
Tropical Indian Ocean ◽  
Distribution Patterns ◽  
Sediment Traps ◽  
Published Data ◽  
Foraminiferal Assemblage ◽  
Planktic Foraminifera ◽  
Neogloboquadrina Dutertrei

Abstract. Planktic foraminifera are widely used in palaeoceanographic and paleoclimatic studies. The accuracy of such reconstructions depends on our understanding of the organisms’ ecology. Here we report on field observations of planktic foraminiferal abundances (>150 µm) from 5 depth intervals between 0–500 m water depth at 37 sites in the eastern tropical Indian Ocean. The total planktic foraminiferal assemblage comprises 29 morphospecies; with 11 morphospecies accounting for ~90 % of the total assemblage. Both species composition and dominance in the net samples are broadly consistent with the published data from the corresponding surface sediments. The abundance and vertical distribution of planktic foraminifera are low offshore west Sumatra, and increase towards offshore south Java and the Lesser Sunda Islands (LSI). Average living depth of Trilobatus trilobus, Globigerinoides ruber, and Globigerina bulloides increases eastward, while that of Neogloboquadrina dutertrei, Pulleniatina obliquiloculata, and Globorotalia menardii remains constant. We interpret the overall zonal and vertical distribution patterns in planktic foraminiferal abundances as a response to the contrasting upper water column conditions during the southeast monsoon, i.e., oligotrophic and stratified offshore Sumatra (non-upwelling) vs. eutrophic and well-mixed offshore Java-LSI (upwelling). Overall, the inferred habitat depths of selected planktic foraminifera species show a good agreement with those from sediment trap samples and from surface sedimentss off Sumatra, but not with those from surface sediments off Java-LSI. The discrepancy might stem from the different temporal coverage of these sample types. Our findings highlight the need to consider how foraminiferal assemblages and ecology vary on shorter timescales, i.e., from “snapshots” of the water column captured by plankton net to seasonal and interannual variability as recorded in sediment traps and how these changes are transferred and preserved in deep-sea sediments.

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