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David W. Blowes - One of the best experts on this subject based on the ideXlab platform.
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mine drainage from the weathering of sulfide minerals and magnetite
Applied Geochemistry, 2009Co-Authors: J L Jambor, M C Moncur, Carol J Ptacek, David W. BlowesAbstract:Pyrite and pyrrhotite are the principal minerals that generate acid drainage in mine wastes. Low-pH conditions derived from Fe-sulfide oxidation result in the mobilization of contaminant metals (such as Zn, Cd, Ni and Cr) and metalloids (such as As) which are of environmental concern. This paper uses data from detailed mineralogical and geochemical studies conducted at two Canadian tailings Impoundments to examine the mineralogical changes that pyrite, pyrrhotite, sphalerite and magnetite undergo during and after sulfide oxidation, and the subsequent release and attenuation of associated trace elements. The stability of sphalerite in tailings Impoundments generally is greater than that of pyrrhotite, but less than pyrite. Dissolved Ni and Co derived from Fe sulfides, and to a lesser extent, dissolved Zn and Cd from sphalerite, are commonly attenuated by early-formed Fe oxyhydroxides. As oxidation progresses, a recycling occurs due to continued leaching from low-pH pore waters and because the crystallinity of Fe oxyhydroxides gradually increases which decreases their sorptive capacity. Unlike many other elements, such as Cu, Pb and Cr, which form secondary minerals or remain incorporated into mature Fe oxyhydroxides, Zn and Ni become mobile. Magnetite, which is a potential source of Cr, is relatively stable except under extremely low-pH conditions. A conceptual model for the sequence of events that typically occurs in an oxidizing tailings Impoundment is developed outlining the progressive oxidation of a unit of mine waste containing a mixed assemblage of pyrrhotite and pyrite.
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geochemical mineralogical and microbiological characterization of a sulphide bearing carbonate rich gold mine tailings Impoundment joutel quebec
Applied Geochemistry, 1998Co-Authors: David W. Blowes, John L Jambor, Christine J Hantonfong, Lyne Lortie, Douglas W GouldAbstract:Abstract The results of an integrated geochemical and mineralogical study conducted at the Agnico-Eagle gold-mine tailings Impoundment, Joutel, Quebec, are correlated with bacterial populations determined from an enumeration of 3 groups of Thiobacilli . The tailings were determined to contain approximately 5 wt.% sulphide–S, predominantly as pyrite, and up to 30 wt.% carbonate minerals, chiefly as dolomite–ankerite and siderite. The objective of the study was to evaluate the potential for the development of acidic drainage and dissolved-metal migration in carbonate-rich tailings Impoundments, and to compare the results of the geochemical and microbiological characterization of the tailings. Sulphide-oxidation reactions have proceeded to a depth of 20–100 cm below the tailings surface. Pyrrhotite consistently shows more alteration than pyrite and arsenopyrite. Pyrrhotite is altered mainly through the replacement by goethite. The most abundant Thiobacilli are neutrophilic bacteria of the Thiobacillus thioparus type. The maximum most probable number values for these bacteria occur 20–40 cm below the tailings surface, a depth that coincides with the disappearance of oxide coatings. This observation, coupled with the sharp decline in gas-phase O 2 concentration, suggests that rapid bacterially-mediated S–oxidation is occurring at this depth. The pore-water pH throughout the tailings varies between 6.5 and 8.5; no low-pH waters were observed in the Impoundment. These neutral pH conditions are attributed to the effect of acid-consuming carbonate-mineral dissolution reactions, which are also indicated by increased concentrations of Mg and Ca and alkalinity in the shallow zone of the tailings. As a result of these acid-neutralization reactions, dissolved metal concentrations are low.
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the formation and potential importance of cemented layers in inactive sulfide mine tailings
Geochimica et Cosmochimica Acta, 1991Co-Authors: David W. Blowes, Eric J Reardon, John L Jambor, John A CherryAbstract:Abstract Investigations of inactive sulfide-rich tailings Impoundments at the Heath Steele (New Brunswick) and Waite Amulet (Quebec) minesites have revealed two distinct types of cemented layers or “hardpans.” That at Heath Steele is 10–15 cm thick, occurs 20–30 cm below the depth of active oxidation, is continuous throughout the tailings Impoundment, and is characterized by cementation of tailings by gypsum and Fe(II) solid phases, principally melanterite. Hardpan at the Waite Amulet site is only 1–5 cm thick, is laterally discontinuous (10–100 cm), occurs at the depth of active oxidation, and is characterized by cementation of tailings by Fe(III) minerals, principally goethite, lepidocrocite, ferrihydrite, and jarosite. At Heath Steele, an accumulation of gas-phase CO2, of up to 60% of the pore gas, occurs below the hardpan. The calculated diffusivity of the hardpan layer is only about 1 100 that of the overlying, uncemented tailings. The pore-water chemistry at Heath Steele has changed little over a 10-year period, suggesting that the cemented layer restricts the movement of dissolved metals through the tailings and also acts as a zone of metal accumulation. Generation of a cemented layer therefore has significant environmental and economic implications. It is likely that, in sulfide-rich tailings Impoundments, the addition of carbonate-rich buffering material during the late stages of tailings deposition would enhance the formation of hardpan layers.
Genming Zhao - One of the best experts on this subject based on the ideXlab platform.
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the impact of water level changes on the oncomelania snail habitats in poyang lake regions before and after the Impoundment of three gorges reservoir
Chinese Journal of Preventive Medicine, 2013Co-Authors: Yi-biao Zhou, Zhanying He, Xiaolin Xu, Lijuan Zhang, Genming ZhaoAbstract:Objective To explore the impact of the Impoundment of Three Gorges reservoir on Oncomelania snail habitats of Poyang Lake.Methods Four counties with schistosomiasis endemic around the Poyang Lake,naming as Xingzi,Duchang,Jinxian and Xinjian,were selected as study areas.The average daily water level of four major hydrological stations near the above 4 counties from 1997 to 2008 were collected,as well as the elevation of 215 marshlands with snails in those 4 counties,the data of schistosomiasis endemic situation and snail survey of 4 counties in the year before the Impoundment of Three Gorges reservoir (2002) and the 6th year after the Impoundment of Three Gorges reservoir (2008).The fluctuations of water levels of Poyang Lake,flooding day of marshland with snails as well as the changes of the indicators in snail survey and prevention and control measures before and after the Impoundment of Three Gorges reservoir were compared.Results Before the Impoundment of Three Gorges reservoir,the fluctuations of average water level of the four hydrological stations around Poyang Lake was 6.91-12.93 m; which reduced to 5.72-10.75 m after the Impoundment.The D-value of the fluctuations of average water level was (1.06 ±0.47) m.The date of the annual maximum water level delayed by an average of 12 d; while the date of annual minimum water level arrived an average of 12 d earlier than the Impoundment of Three Gorges reservoir.The average flooding days of marshland with snails were separately (100.04 ± 42.06) d before the Impoundment and (64.13 ± 22.30) d after the Impoundment.The difference was statistically significant (t =3.70,P ＜ 0.05).The density of snails in the 4 counties around Poyang Lake was 0.8437/0.1 m2 after the Impoundment; declining by 31.04％ from the snail density (1.2234/0.1 m2) before the Impoundment.The density of infectious snails was 0.0014/0.1 m2 after the Impoundment; dropping by 67.34％ from it (0.0042/0.1 m2) before the Impoundment; the infection rate of snails was separately 0.34％ after the Impoundment and 0.16％ before the Impoundment.The difference was statistically significant (x2 =53.25,P ＜ 0.05).The coverage rate of chemotherapy increased from 4.45％ (35 558/798 200) in 2002 to 9.80％(79 457/810 400) in 2008 ; the difference was statistically significant (x2 =17 336.63,P ＜ 0.05).The coverage rate of snail killing increased from 1.35％ (389.04/28 824.66) in 2002 to 7.49％ (2260.90/30 166.22) in 2008; the difference was also statistically significant (x2 =28 824.66,P ＜ 0.05).Conclusion The impact of the Impoundment of Three Gorges reservoir shortened the flooding days of marshland with snails and helped the prevention and control of schistosomiasis in Poyang Lake regions as the environment went against the breeding of the snails. Key words: Schistosomiasis; Environmental monitoring; Three Gorges reservoir
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the impact of water level changes on the oncomelania snail habitats in poyang lake regions before and after the Impoundment of three gorges reservoir
Chinese Journal of Preventive Medicine, 2013Co-Authors: Yi-biao Zhou, Zhanying He, Xiaolin Xu, Lijuan Zhang, Genming ZhaoAbstract:Objective To explore the impact of the Impoundment of Three Gorges reservoir on Oncomelania snail habitats of Poyang Lake.Methods Four counties with schistosomiasis endemic around the Poyang Lake,naming as Xingzi,Duchang,Jinxian and Xinjian,were selected as study areas.The average daily water level of four major hydrological stations near the above 4 counties from 1997 to 2008 were collected,as well as the elevation of 215 marshlands with snails in those 4 counties,the data of schistosomiasis endemic situation and snail survey of 4 counties in the year before the Impoundment of Three Gorges reservoir (2002) and the 6th year after the Impoundment of Three Gorges reservoir (2008).The fluctuations of water levels of Poyang Lake,flooding day of marshland with snails as well as the changes of the indicators in snail survey and prevention and control measures before and after the Impoundment of Three Gorges reservoir were compared.Results Before the Impoundment of Three Gorges reservoir,the fluctuations of average water level of the four hydrological stations around Poyang Lake was 6.91-12.93 m; which reduced to 5.72-10.75 m after the Impoundment.The D-value of the fluctuations of average water level was (1.06 ±0.47) m.The date of the annual maximum water level delayed by an average of 12 d; while the date of annual minimum water level arrived an average of 12 d earlier than the Impoundment of Three Gorges reservoir.The average flooding days of marshland with snails were separately (100.04 ± 42.06) d before the Impoundment and (64.13 ± 22.30) d after the Impoundment.The difference was statistically significant (t =3.70,P ＜ 0.05).The density of snails in the 4 counties around Poyang Lake was 0.8437/0.1 m2 after the Impoundment; declining by 31.04％ from the snail density (1.2234/0.1 m2) before the Impoundment.The density of infectious snails was 0.0014/0.1 m2 after the Impoundment; dropping by 67.34％ from it (0.0042/0.1 m2) before the Impoundment; the infection rate of snails was separately 0.34％ after the Impoundment and 0.16％ before the Impoundment.The difference was statistically significant (x2 =53.25,P ＜ 0.05).The coverage rate of chemotherapy increased from 4.45％ (35 558/798 200) in 2002 to 9.80％(79 457/810 400) in 2008 ; the difference was statistically significant (x2 =17 336.63,P ＜ 0.05).The coverage rate of snail killing increased from 1.35％ (389.04/28 824.66) in 2002 to 7.49％ (2260.90/30 166.22) in 2008; the difference was also statistically significant (x2 =28 824.66,P ＜ 0.05).Conclusion The impact of the Impoundment of Three Gorges reservoir shortened the flooding days of marshland with snails and helped the prevention and control of schistosomiasis in Poyang Lake regions as the environment went against the breeding of the snails. Key words: Schistosomiasis; Environmental monitoring; Three Gorges reservoir
Jinsong Guo - One of the best experts on this subject based on the ideXlab platform.
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the net ghg emissions of the china three gorges reservoir i pre Impoundment ghg inventories and carbon balance
Journal of Cleaner Production, 2020Co-Authors: Zhiyu Sun, Yongbo Chen, Zhenhua Pan, Atle Harby, Dan Chen, Jinsong GuoAbstract:Abstract One of the paramount questions related to environmental and climate change impacts from hydropower and reservoirs, is how to quantify the greenhouse gas (GHG) emissions of dam construction and reservoir creation, mostly in terms of reservoir net GHG emissions. Net emissions are described as the emissions after Impoundment subtracting the emissions before the reservoir was built (pre-Impoundment). The evaluation of pre-Impoundment GHG emissions is essential to answer the above questions, yet there are few related case studies. Herein, we proposed a conceptual framework to evaluate the pre-Impoundment GHG emissions of China’s Three Gorges Reservoir (TGR). Reservoir flooded areas prior to Impoundment were divided into two categories: 1) flooded land, where pre-Impoundment CO2 and CH4 fluxes from different historical land uses were estimated following tier 1 methodology of IPCC national inventories, and 2) river surface, where pre-Impoundment CO2 fluxes were estimated by a calibrated two dimensional modified biogeochemical model with an air-water gas transfer module. An empirical regression model between measured air-water CO2 and CH4 fluxes in unflooded river reaches was used to estimate pre-Impoundment river surface CH4 flux. The pre-Impoundment GHG emissions of the TGR were 5.1 × 105 tCO2eq·yr−1, with 95% confidence intervals of 4.7–6.1 × 105 tCO2eq·yr−1. Approximately 46% of the pre-Impoundment GHG emissions were from flooded land, while the rest 54% were from river surfaces. Mass balance indicated that approximately 72% of the downstream riverine C export was from the upstream river basin of the Yangtze River. Pre-Impoundment C emissions were only ∼6.58% of the total riverine C export downstream. Most of the C in the system was mainly from the upstream river basin of the Yangtze River; thus, an increase in anthropogenic loads of C and nutrients in the Three Gorges Reservoir Area did not result in an apparent increase in pre-Impoundment river surface GHG emissions.
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carbon footprints of pre Impoundment clearance on reservoir flooded area in china s large hydro projects implications for ghg emissions reduction in the hydropower industry
Journal of Cleaner Production, 2017Co-Authors: Jinsong GuoAbstract:Abstract Pre-Impoundment clearance in an area to be flooded by a reservoir is a commonly applied engineering measure to remove vegetation cover, buildings, structures and solid waste landfill as a clean production approach in the hydropower industry. By removing forests and trees, pre-Impoundment clearance is also among one of the most applicable and practical measures to significantly minimize the potential increase in greenhouse gas (GHG) emissions after reservoir Impoundment. By using Economic Input-Output Life Cycle Assessment (EIO-LCA) method and following ISO 14067, the present study evaluated carbon footprints of pre-Impoundment clearance in China's five largest hydro-projects: the Three Gorges Dam Project (TGD), the Xiangjiaba Project, the Xiluodu Project, the Baihetan Project, and the Wudongde Project, and discussed the trade-offs between these carbon footprints and the contributions to GHG emission reductions from pre-Impoundment clearance. The carbon footprints of pre-Impoundment clearance in these hydro-projects ranged from 0.020 gCO2eq·kWh−1 to 0.434 gCO2eq·kWh−1; the TGD project had the maximum carbon footprint among the hydro-projects. Removal of buildings, structures, and solid wastes created the largest share (over 95%) of carbon footprints of pre-Impoundment clearance. Removal of forests and trees in pre-Impoundment clearance could possibly reduce potential GHG emissions after reservoir Impoundment, which equal to approximately 14.43%–246.80% of pre-Impoundment clearance. Higher anthropogenic activity in terms of population density in reservoir areas to be flooded and smaller hydro-project energy density resulted in higher carbon footprints from pre-Impoundment clearance. In China's cases, pre-Impoundment clearance is concluded to be a significant measure of GHG emission reduction in hydropower industry.
Katrine Turgeon - One of the best experts on this subject based on the ideXlab platform.
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dams have varying impacts on fish communities across latitudes a quantitative synthesis
Ecology Letters, 2019Co-Authors: Katrine Turgeon, Christian Turpin, Irene GregoryeavesAbstract:Dams are recognised to impact aquatic biodiversity, but the effects and conclusions diverge across studies and locations. By using a meta-analytical approach, we quantified the effects of Impoundment on fish communities distributed across three large biomes. The impacts of dams on richness and diversity differed across biomes, with significant declines in the tropics, lower amplitude but similar directional changes in temperate regions, and no changes in boreal regions. Our analyses showed that non-native species increased significantly in tropical and temperate regulated rivers, but not in boreal rivers. In contrast, temporal trajectories in fish assemblage metrics were common across regions, with all biomes showing an increase in mean trophic level position and in the proportion of generalist species after Impoundment. Such changes in fish assemblages may affect food web stability and merit closer study. Across the literature examined, predominant mechanisms that render fish assemblages susceptible to impacts from dams were: (1) the transformation of the lotic environment into a lentic environment; (2) habitat fragmentation and (3) the introduction of non-native species. Collectively, our results highlight that an understanding of the regional context and a suite of community metrics are needed to make robust predictions about how fish will respond to river Impoundments.
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dams have varying impacts on fish communities across latitudes a quantitative synthesis
bioRxiv, 2018Co-Authors: Katrine Turgeon, Christian Turpin, Irene GregoryeavesAbstract:Dams are recognized to impact aquatic biodiversity and ecosystem functions, but the magnitude of effects vary across studies. By using a meta-analytical approach, we examined the effects of Impoundment on fish community across three large biomes. The impacts of dams on richness and diversity differed across biomes, with significant declines in the tropics, lower amplitude but similar directional changes in temperate reservoirs, and no changes in boreal reservoirs. Our analysis also showed that non-native species increased significantly in tropical and temperate reservoirs, but not in boreal reservoirs. In contrast, temporal trajectories in fish assemblage metrics were common across regions, with all biomes showing an increase in mean trophic position and in the proportion of generalist species after Impoundment. Such changes in fish assemblages may affect food web stability and merit closer study. Across the literature examined, predominant factors or mechanisms that render fish assemblages susceptible to impacts from dams were: 1) the transformation of the lotic environment into a lentic environment; 2) habitat fragmentation and 3) invasive or non-native species. Collectively our results highlight that an understanding of the regional context and a suite of metrics are needed to make robust predictions about how fish will respond to river Impoundments.
Yi-biao Zhou - One of the best experts on this subject based on the ideXlab platform.
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the impact of water level changes on the oncomelania snail habitats in poyang lake regions before and after the Impoundment of three gorges reservoir
Chinese Journal of Preventive Medicine, 2013Co-Authors: Yi-biao Zhou, Zhanying He, Xiaolin Xu, Lijuan Zhang, Genming ZhaoAbstract:Objective To explore the impact of the Impoundment of Three Gorges reservoir on Oncomelania snail habitats of Poyang Lake.Methods Four counties with schistosomiasis endemic around the Poyang Lake,naming as Xingzi,Duchang,Jinxian and Xinjian,were selected as study areas.The average daily water level of four major hydrological stations near the above 4 counties from 1997 to 2008 were collected,as well as the elevation of 215 marshlands with snails in those 4 counties,the data of schistosomiasis endemic situation and snail survey of 4 counties in the year before the Impoundment of Three Gorges reservoir (2002) and the 6th year after the Impoundment of Three Gorges reservoir (2008).The fluctuations of water levels of Poyang Lake,flooding day of marshland with snails as well as the changes of the indicators in snail survey and prevention and control measures before and after the Impoundment of Three Gorges reservoir were compared.Results Before the Impoundment of Three Gorges reservoir,the fluctuations of average water level of the four hydrological stations around Poyang Lake was 6.91-12.93 m; which reduced to 5.72-10.75 m after the Impoundment.The D-value of the fluctuations of average water level was (1.06 ±0.47) m.The date of the annual maximum water level delayed by an average of 12 d; while the date of annual minimum water level arrived an average of 12 d earlier than the Impoundment of Three Gorges reservoir.The average flooding days of marshland with snails were separately (100.04 ± 42.06) d before the Impoundment and (64.13 ± 22.30) d after the Impoundment.The difference was statistically significant (t =3.70,P ＜ 0.05).The density of snails in the 4 counties around Poyang Lake was 0.8437/0.1 m2 after the Impoundment; declining by 31.04％ from the snail density (1.2234/0.1 m2) before the Impoundment.The density of infectious snails was 0.0014/0.1 m2 after the Impoundment; dropping by 67.34％ from it (0.0042/0.1 m2) before the Impoundment; the infection rate of snails was separately 0.34％ after the Impoundment and 0.16％ before the Impoundment.The difference was statistically significant (x2 =53.25,P ＜ 0.05).The coverage rate of chemotherapy increased from 4.45％ (35 558/798 200) in 2002 to 9.80％(79 457/810 400) in 2008 ; the difference was statistically significant (x2 =17 336.63,P ＜ 0.05).The coverage rate of snail killing increased from 1.35％ (389.04/28 824.66) in 2002 to 7.49％ (2260.90/30 166.22) in 2008; the difference was also statistically significant (x2 =28 824.66,P ＜ 0.05).Conclusion The impact of the Impoundment of Three Gorges reservoir shortened the flooding days of marshland with snails and helped the prevention and control of schistosomiasis in Poyang Lake regions as the environment went against the breeding of the snails. Key words: Schistosomiasis; Environmental monitoring; Three Gorges reservoir
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the impact of water level changes on the oncomelania snail habitats in poyang lake regions before and after the Impoundment of three gorges reservoir
Chinese Journal of Preventive Medicine, 2013Co-Authors: Yi-biao Zhou, Zhanying He, Xiaolin Xu, Lijuan Zhang, Genming ZhaoAbstract:Objective To explore the impact of the Impoundment of Three Gorges reservoir on Oncomelania snail habitats of Poyang Lake.Methods Four counties with schistosomiasis endemic around the Poyang Lake,naming as Xingzi,Duchang,Jinxian and Xinjian,were selected as study areas.The average daily water level of four major hydrological stations near the above 4 counties from 1997 to 2008 were collected,as well as the elevation of 215 marshlands with snails in those 4 counties,the data of schistosomiasis endemic situation and snail survey of 4 counties in the year before the Impoundment of Three Gorges reservoir (2002) and the 6th year after the Impoundment of Three Gorges reservoir (2008).The fluctuations of water levels of Poyang Lake,flooding day of marshland with snails as well as the changes of the indicators in snail survey and prevention and control measures before and after the Impoundment of Three Gorges reservoir were compared.Results Before the Impoundment of Three Gorges reservoir,the fluctuations of average water level of the four hydrological stations around Poyang Lake was 6.91-12.93 m; which reduced to 5.72-10.75 m after the Impoundment.The D-value of the fluctuations of average water level was (1.06 ±0.47) m.The date of the annual maximum water level delayed by an average of 12 d; while the date of annual minimum water level arrived an average of 12 d earlier than the Impoundment of Three Gorges reservoir.The average flooding days of marshland with snails were separately (100.04 ± 42.06) d before the Impoundment and (64.13 ± 22.30) d after the Impoundment.The difference was statistically significant (t =3.70,P ＜ 0.05).The density of snails in the 4 counties around Poyang Lake was 0.8437/0.1 m2 after the Impoundment; declining by 31.04％ from the snail density (1.2234/0.1 m2) before the Impoundment.The density of infectious snails was 0.0014/0.1 m2 after the Impoundment; dropping by 67.34％ from it (0.0042/0.1 m2) before the Impoundment; the infection rate of snails was separately 0.34％ after the Impoundment and 0.16％ before the Impoundment.The difference was statistically significant (x2 =53.25,P ＜ 0.05).The coverage rate of chemotherapy increased from 4.45％ (35 558/798 200) in 2002 to 9.80％(79 457/810 400) in 2008 ; the difference was statistically significant (x2 =17 336.63,P ＜ 0.05).The coverage rate of snail killing increased from 1.35％ (389.04/28 824.66) in 2002 to 7.49％ (2260.90/30 166.22) in 2008; the difference was also statistically significant (x2 =28 824.66,P ＜ 0.05).Conclusion The impact of the Impoundment of Three Gorges reservoir shortened the flooding days of marshland with snails and helped the prevention and control of schistosomiasis in Poyang Lake regions as the environment went against the breeding of the snails. Key words: Schistosomiasis; Environmental monitoring; Three Gorges reservoir
