Microbial communities, processes and functions in acid mine drainage ecosystems.

PubMed

Chen, Lin-xing; Huang, Li-nan; Méndez-García, Celia; Kuang, Jia-liang; Hua, Zheng-shuang; Liu, Jun; Shu, Wen-sheng

2016-04-01

Acid mine drainage (AMD) is generated from the oxidative dissolution of metal sulfides when water and oxygen are available largely due to human mining activities. This process can be accelerated by indigenous microorganisms. In the last several decades, culture-dependent researches have uncovered and validated the roles of AMD microorganisms in metal sulfides oxidation and acid generation processes, and culture-independent studies have largely revealed the diversity and metabolic potentials and activities of AMD communities, leading towards a full understanding of the microbial diversity, functions and interactions in AMD ecosystems. This review describes the diversity of microorganisms and their functions in AMD ecosystems, and discusses their biotechnological applications in biomining and AMD bioremediation according to their capabilities. Copyright © 2016 Elsevier Ltd. All rights reserved.

DEVELOPMENT OF SRB TREATMENT SYSTEMS FOR ACID MINE DRAINAGE

EPA Science Inventory

Over the past decade, significant advances have been made in the development of sulfate- reducing bacteria (SRB) technology to treat acid mine drainage (AMD), Bench-scale testing, field demonstrations, and engineered applications of SRBs for the treatment of AMD will be presented...

Heavy Metals and Radioactivity Reduction from Acid Mine Drainage Lime Neutralized Sludge

NASA Astrophysics Data System (ADS)

Mashifana, T.; Sithole, N.

2018-03-01

The worldwide known treatment processes of acid mine drainage result into the formation of hydrous ferric oxides that is amorphous, poorly crystalline and into the generation of hazardous voluminous sludge posing threat to the environment. Applicable treatment technologies to treat hazardous solid material and produce useful products are limited and in most cases nonexistence. A chemical treatment process utilizing different reagents was developed to treat hazardous acid mine drainage (AMD) sludge with the objectives to conduct radioactivity assessment of the sludge generated from lime treatment process and determine the reagent that provides the best results. Leaching with 0.5 M citric acid, 0.4 M oxalic acid, 0.5 M sodium carbonate and 0.5 M sodium bicarbonate was investigated. The leaching time applied was 24 hours at 25 °C. The characterization of the raw AMD revealed that the AMD sludge from lime treatment process is radioactive. The sludge was laden with radioactive elements namely, 238U, 214Pb, 226Ra, 232Th, 40K and 214Bi. 0.5 M citric acid provided the best results and the hazardous contaminants were significantly reduced. The constituents in the sludge after treatment revealed that there is a great potential for the sludge to be used for other applications such as building and construction.

Removal of sulphates acidity and iron from acid mine drainage in a bench scale biochemical treatment system.

PubMed

Prasad, D; Henry, J G

2009-02-01

The focus of this study was to develop a simple biochemical system to treat acid mine drainage for its safe disposal. Recovery and reuse of the metals removed were not considered. A three-step process for the treatment of acid mine drainage (AMD), proposed earlier, separates sulphate reducing activity from metal precipitation units and from a pH control system. Following our earlier work on the first step (biological reactor), this paper examines the second step (i.e. chemical reactor). The objectives of this study were: (1) to determine the increase in pH and the reduction of iron in the chemical reactor for different proportions of simulated AMD, and (2) to assess the capability of the chemical reactor. A series of experiments was conducted to study the effects of addition of alkaline sulphidogenic liquor (ASL) derived from a batch sulphidogenic biological reactor (operating with activated sludge and a COD/SO4 ratio of 1.6) on the simulated AMD characteristics. At 60-minute contact time, addition of 30% ASL (pH of 7.60-7.76) to the chemical reactor with 70% AMD (pH of 1.65-2.02), increased the pH of the AMD to 6.57 and alkalinity from 0 to 485 mg l(-1) as CaCO3, respectively and precipitated about 97% of the iron present in the simulated AMD. Others have demonstrated that metals in mine drainage can be precipitated by bacterial sulphate reduction. In this study, iron, a common and major component of mine drainage was used as a surrogate for metals in general. The results indicate the feasibility of treating AMD by an engineered sulphidogenic anaerobic reactor followed by a chemical reactor and that our three-step biochemical process has important advantages over other conventional AMD treatment systems.

PREVENTION OF ACID MINE DRAINAGE GENERATION FROM OPEN-PIT MINE HIGHWALLS

EPA Science Inventory

Exposed, open pit mine highwalls contribute significantly to the production of acid mine

drainage (AMD) thus causing environmental concerns upon closure of an operating mine. Available information on the generation of AMD from open-pit mine highwalls is very limit...

Spectral masking of goethite in abandoned mine drainage systems: implications for Mars

USGS Publications Warehouse

Cull, Selby; Cravotta, Charles A.; Klinges, Julia Grace; Weeks, Chloe

2014-01-01

Remote sensing studies of the surface of Mars use visible- to near-infrared (VNIR) spectroscopy to identify hydrated and hydroxylated minerals, which can be used to constrain past environmental conditions on the surface of Mars. However, due to differences in optical properties, some hydrated phases can mask others in VNIR spectra, complicating environmental interpretations. Here, we examine the role of masking in VNIR spectra of natural precipitates of ferrihydrite, schwertmannite, and goethite from abandoned mine drainage (AMD) systems in southeastern Pennsylvania. Mixtures of ferrihydrite, schwertmannite, and goethite were identified in four AMD sites by using X-ray diffractometry (XRD), and their XRD patterns compared to their VNIR spectra. We find that both ferrihydrite and schwertmannite can mask goethite in VNIR spectra of natural AMD precipitates. These findings suggest that care should be taken in interpreting environments on Mars where ferrihydrite, schwertmannite, or goethite are found, as the former two may be masking the latter. Additionally, our findings suggest that outcrops on Mars with both goethite and ferrihydrite/schwertmannite VNIR signatures may have high relative abundances of goethite, or the goethite may exist in a coarsely crystalline phase.

Novel and Unexpected Microbial Diversity in Acid Mine Drainage in Svalbard (78° N), Revealed by Culture-Independent Approaches

PubMed Central

García-Moyano, Antonio; Austnes, Andreas Erling; Lanzén, Anders; González-Toril, Elena; Aguilera, Ángeles; Øvreås, Lise

2015-01-01

Svalbard, situated in the high Arctic, is an important past and present coal mining area. Dozens of abandoned waste rock piles can be found in the proximity of Longyearbyen. This environment offers a unique opportunity for studying the biological control over the weathering of sulphide rocks at low temperatures. Although the extension and impact of acid mine drainage (AMD) in this area is known, the native microbial communities involved in this process are still scarcely studied and uncharacterized. Several abandoned mining areas were explored in the search for active AMD and a culture-independent approach was applied with samples from two different runoffs for the identification and quantification of the native microbial communities. The results obtained revealed two distinct microbial communities. One of the runoffs was more extreme with regards to pH and higher concentration of soluble iron and heavy metals. These conditions favored the development of algal-dominated microbial mats. Typical AMD microorganisms related to known iron-oxidizing bacteria (Acidithiobacillus ferrivorans, Acidobacteria and Actinobacteria) dominated the bacterial community although some unexpected populations related to Chloroflexi were also significant. No microbial mats were found in the second area. The geochemistry here showed less extreme drainage, most likely in direct contact with the ore under the waste pile. Large deposits of secondary minerals were found and the presence of iron stalks was revealed by microscopy analysis. Although typical AMD microorganisms were also detected here, the microbial community was dominated by other populations, some of them new to this type of system (Saccharibacteria, Gallionellaceae). These were absent or lowered in numbers the farther from the spring source and they could represent native populations involved in the oxidation of sulphide rocks within the waste rock pile. This environment appears thus as a highly interesting field of potential novelty in terms of both phylogenetic/taxonomic and functional diversity. PMID:27682111

VALUING ACID MINE DRAINAGE REMEDIATION IN WEST VIRGINIA: A HEDONIC MODELING APPROACH

EPA Science Inventory

States with active and abandoned mines face large private and public costs to remediate damage to streams and rivers from acid mine drainage (AMD). Appalachian states have an especially large number of contaminated streams and rivers, and the USGS places AMD as the primary source...

Ecological roles of dominant and rare prokaryotes in acid mine drainage revealed by metagenomics and metatranscriptomics.

PubMed

Hua, Zheng-Shuang; Han, Yu-Jiao; Chen, Lin-Xing; Liu, Jun; Hu, Min; Li, Sheng-Jin; Kuang, Jia-Liang; Chain, Patrick S G; Huang, Li-Nan; Shu, Wen-Sheng

2015-06-01

High-throughput sequencing is expanding our knowledge of microbial diversity in the environment. Still, understanding the metabolic potentials and ecological roles of rare and uncultured microbes in natural communities remains a major challenge. To this end, we applied a 'divide and conquer' strategy that partitioned a massive metagenomic data set (>100 Gbp) into subsets based on K-mer frequency in sequence assembly to a low-diversity acid mine drainage (AMD) microbial community and, by integrating with an additional metatranscriptomic assembly, successfully obtained 11 draft genomes most of which represent yet uncultured and/or rare taxa (relative abundance <1%). We report the first genome of a naturally occurring Ferrovum population (relative abundance >90%) and its metabolic potentials and gene expression profile, providing initial molecular insights into the ecological role of these lesser known, but potentially important, microorganisms in the AMD environment. Gene transcriptional analysis of the active taxa revealed major metabolic capabilities executed in situ, including carbon- and nitrogen-related metabolisms associated with syntrophic interactions, iron and sulfur oxidation, which are key in energy conservation and AMD generation, and the mechanisms of adaptation and response to the environmental stresses (heavy metals, low pH and oxidative stress). Remarkably, nitrogen fixation and sulfur oxidation were performed by the rare taxa, indicating their critical roles in the overall functioning and assembly of the AMD community. Our study demonstrates the potential of the 'divide and conquer' strategy in high-throughput sequencing data assembly for genome reconstruction and functional partitioning analysis of both dominant and rare species in natural microbial assemblages.

Acid mine drainage

USGS Publications Warehouse

Bigham, Jerry M.; Cravotta, Charles A.

2016-01-01

Acid mine drainage (AMD) consists of metal-laden solutions produced by the oxidative dissolution of iron sulfide minerals exposed to air, moisture, and acidophilic microbes during the mining of coal and metal deposits. The pH of AMD is usually in the range of 2–6, but mine-impacted waters at circumneutral pH (5–8) are also common. Mine drainage usually contains elevated concentrations of sulfate, iron, aluminum, and other potentially toxic metals leached from rock that hydrolyze and coprecipitate to form rust-colored encrustations or sediments. When AMD is discharged into surface waters or groundwaters, degradation of water quality, injury to aquatic life, and corrosion or encrustation of engineered structures can occur for substantial distances. Prevention and remediation strategies should consider the biogeochemical complexity of the system, the longevity of AMD pollution, the predictive power of geochemical modeling, and the full range of available field technologies for problem mitigation.

ADVANCES IN BIOTREATMENT OF ACID MINE DRAINAGE AND BIORECOVERY OF METALS: 1. METAL PRECIPITATION FOR RECOVERY AND RECYCLE

EPA Science Inventory

Acid-mine drainage (AMD) is a severe pollution problem attributed to past mining activities. AMD is an acidic, metal-bearing wastewater generated by the oxidation of metal sulfides to sulfates by Thiobacillus bacteria in both active and abandoned mining operations. The wastewater...

VALUING ACID MINE DRAINAGE REMEDIATION OF IMPAIRED WATERWAYS IN WEST VIRGINIA: A HEDONIC MODELING APPROACH

EPA Science Inventory

States with active and abandoned mines face large private and public costs to remediate damage to streams and rivers from acid mine drainage (AMD), the metal rich runoff flowing primarily from abandoned mines and surface deposits of mine waste. AMD can lower stream and river pH ...

ADVANCES IN BIOTREATMENT OF ACID MINE DRAINAGE AND BIORECOVERY OF METALS: 2. MEMBRANE BIOREACTOR SYSTEM FOR SULFATE REDUCTION

EPA Science Inventory

Acid-mine drainage (AMD) is a severe pollution problem attributed to past mining activities. AMD is an acidic, metal-bearing wastewater generated by the oxidation of metal sulfides to sulfates by Thiobacillus bacteria in both the active and abandoned mining operations. The wastew...

VALUING ACID MINE DRAINAGE REMEDIATION IN WEST VIRGINIA: A HEDONIC MODELING APPROACH INCORPORATING GEOGRAPHIC INFORMATION SYSTEMS

EPA Science Inventory

States with active and abandoned mines face large private and public costs to remediate damage to streams and rivers from acid mine drainage (AMD). Appalachian states have an especially large number of contaminated streams and rivers, and the USGS places AMD as the primary source...

Marine macroalgal community structure, metal content and reproductive function near an acid mine drainage outflow.

PubMed

Marsden, A D; DeWreede, R E

2000-12-01

Marine macroalgal communities were examined near the outflow of acid mine drainage (AMD) from the Britannia Mine, British Columbia, Canada. No marine algae were present within 100 m of the mouth of Britannia Creek, which carries the AMD into the marine environment. At greater distances (300-700 m) from this Creek, mean summer cover of filamentous green algae, mostly Enteromorpha intestinalis, was >60%, which was significantly higher than at nearby reference stations. At still greater distances (600-1000 m) from Britannia Creek, Fucus gardneri dominated algal communities that were similar to those at reference stations. No consistent differences were detected in mean plant length, mean per cent cover or mean oocyte production between F. gardneri near Britannia Creek and those at reference stations. Cu body burden in F. gardneri near Britannia Creek was five to 17 times higher than in reference plants.

A combined CaO/electrochemical treatment of the acid mine drainage from the "Robule" Lake.

PubMed

Orescanin, Visnja; Kollar, Robert

2012-01-01

The purpose of this work was development and application of the purification system suitable for the treatment of the acid mine drainage (AMD) accumulated in the "Robule" Lake, which represents the part of the Bor copper mining and smelting complex, Serbia. The study was undertaken in order to minimize adverse effect on the environment caused by the discharge of untreated AMD, which was characterized with low pH value (2.63) and high concentration of heavy metals (up to 610 mg/L) and sulfates (up to 12,000 mg/L). The treatment of the effluent included pretreatment/pH adjustment with CaO followed by electrocoagulation using iron and aluminum electrode sets. Following the final treatment, the decrease in the concentration of heavy metals ranged from 40 up to 61000 times depending on the metal and its initial concentration. The parameters, color and turbidity were removed completely in the pretreatment step, while the removal efficiencies for other considered parameters were as follows: EC = 55.48%, SO(4) (2-) = 70.83%, Hg = 98.36%, Pb = 97.50%, V = 98.43%, Cr = 99.86%, Mn = 97.96%, Fe = 100.00%, Co = 99.96%, Ni = 99.78%, Cu = 99.99% and Zn = 99.94%. Because the concentrations of heavy metals in the electrochemically treated AMD (ranging from 0.001 to 0.336 mg/L) are very low, the negative impact of this effluent on the aquatic life and humans is not expected. The sludge generated during the treatment of AMD is suitable for reuse for at least two purposes (pretreatment of AMD and covering of the flotation waste heap). From the presented results, it could be concluded that electrochemical treatment is a suitable approach for the treatment of AMD.

Evaluation of airborne thermal infrared imagery for locating mine drainage sites in the Lower Kettle Creek and Cooks Run Basins, Pennsylvania, USA

USGS Publications Warehouse

Sams, James I.; Veloski, Garret

2003-01-01

High-resolution airborne thermal infrared (TIR) imagery data were collected over 90.6 km2 (35 mi2) of remote and rugged terrain in the Kettle Creek and Cooks Run Basins, tributaries of the West Branch of the Susquehanna River in north-central Pennsylvania. The purpose of this investigation was to evaluate the effectiveness of TIR for identifying sources of acid mine drainage (AMD) associated with abandoned coal mines. Coal mining from the late 1800s resulted in many AMD sources from abandoned mines in the area. However, very little detailed mine information was available, particularly on the source locations of AMD sites. Potential AMD sources were extracted from airborne TIR data employing custom image processing algorithms and GIS data analysis. Based on field reconnaissance of 103 TIR anomalies, 53 sites (51%) were classified as AMD. The AMD sources had low pH (<4) and elevated concentrations of iron and aluminum. Of the 53 sites, approximately 26 sites could be correlated with sites previously documented as AMD. The other 27 mine discharges identified in the TIR data were previously undocumented. This paper presents a summary of the procedures used to process the TIR data and extract potential mine drainage sites, methods used for field reconnaissance and verification of TIR data, and a brief summary of water-quality data.

Synthesising acid mine drainage to maintain and exploit indigenous mining micro-algae and microbial assemblies for biotreatment investigations.

PubMed

Orandi, Sanaz; Lewis, David M

2013-02-01

The stringent regulations for discharging acid mine drainage (AMD) has led to increased attention on traditional or emerging treatment technologies to establish efficient and sustainable management for mine effluents. To assess new technologies, laboratory investigations on AMD treatment are necessary requiring a consistent supply of AMD with a stable composition, thus limiting environmental variability and uncertainty during controlled experiments. Additionally, biotreatment systems using live cells, particularly micro-algae, require appropriate nutrient availability. Synthetic AMD (Syn-AMD) meets these requirements. However, to date, most of the reported Syn-AMDs are composed of only a few selected heavy metals without considering the complexity of actual AMD. In this study, AMD was synthesised based on the typical AMD characteristics from a copper mine where biotreatment is being considered using indigenous AMD algal-microbes. Major cations (Ca, Na, Cu, Zn, Mg, Mn and Ni), trace metals (Al, Fe, Ag, Na, Co, Mo, Pb and Cr), essential nutrients (N, P and C) and high SO(4) were incorporated into the Syn-AMD. This paper presents the preparation of chemically complex Syn-AMD and the challenges associated with combining metal salts of varying solubility that is not restricted to one particular mine site. The general approach reported and the particular reagents used can produce alternative Syn-AMD with varying compositions. The successful growth of indigenous AMD algal-microbes in the Syn-AMD demonstrated its applicability as appropriate generic media for cultivation and maintenance of mining microorganisms for future biotreatment studies.

Applications of multi-season hyperspectral remote sensing for acid mine water characterization and mapping of secondary iron minerals associated with acid mine drainage

NASA Astrophysics Data System (ADS)

Davies, Gwendolyn E.

Acid mine drainage (AMD) resulting from the oxidation of sulfides in mine waste is a major environmental issue facing the mining industry today. Open pit mines, tailings ponds, ore stockpiles, and waste rock dumps can all be significant sources of pollution, primarily heavy metals. These large mining-induced footprints are often located across vast geographic expanses and are difficult to access. With the continuing advancement of imaging satellites, remote sensing may provide a useful monitoring tool for pit lake water quality and the rapid assessment of abandoned mine sites. This study explored the applications of laboratory spectroscopy and multi-season hyperspectral remote sensing for environmental monitoring of mine waste environments. Laboratory spectral experiments were first performed on acid mine waters and synthetic ferric iron solutions to identify and isolate the unique spectral properties of mine waters. These spectral characterizations were then applied to airborne hyperspectral imagery for identification of poor water quality in AMD ponds at the Leviathan Mine Superfund site, CA. Finally, imagery varying in temporal and spatial resolutions were used to identify changes in mineralogy over weathering overburden piles and on dry AMD pond liner surfaces at the Leviathan Mine. Results show the utility of hyperspectral remote sensing for monitoring a diverse range of surfaces associated with AMD.

In situ proteo-metabolomics reveals metabolite secretion by the acid mine drainage bio-indicator, Euglena mutabilis

PubMed Central

Halter, David; Goulhen-Chollet, Florence; Gallien, Sébastien; Casiot, Corinne; Hamelin, Jérôme; Gilard, Françoise; Heintz, Dimitri; Schaeffer, Christine; Carapito, Christine; Van Dorsselaer, Alain; Tcherkez, Guillaume; Arsène-Ploetze, Florence; Bertin, Philippe N

2012-01-01

Euglena mutabilis is a photosynthetic protist found in acidic aquatic environments such as peat bogs, volcanic lakes and acid mine drainages (AMDs). Through its photosynthetic metabolism, this protist is supposed to have an important role in primary production in such oligotrophic ecosystems. Nevertheless, the exact contribution of E. mutabilis in organic matter synthesis remains unclear and no evidence of metabolite secretion by this protist has been established so far. Here we combined in situ proteo-metabolomic approaches to determine the nature of the metabolites accumulated by this protist or potentially secreted into an AMD. Our results revealed that the secreted metabolites are represented by a large number of amino acids, polyamine compounds, urea and some sugars but no fatty acids, suggesting a selective organic matter contribution in this ecosystem. Such a production may have a crucial impact on the bacterial community present on the study site, as it has been suggested previously that prokaryotes transport and recycle in situ most of the metabolites secreted by E. mutabilis. Consequently, this protist may have an indirect but important role in AMD ecosystems but also in other ecological niches often described as nitrogen-limited. PMID:22237547

Ecological roles of dominant and rare prokaryotes in acid mine drainage revealed by metagenomics and metatranscriptomics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hua, Zheng-Shuang; Han, Yu-Jiao; Chen, Lin-Xing

Here we report that high-throughput sequencing is expanding our knowledge of microbial diversity in the environment. Still, understanding the metabolic potentials and ecological roles of rare and uncultured microbes in natural communities remains a major challenge. To this end, we applied a ‘divide and conquer’ strategy that partitioned a massive metagenomic data set (>100 Gbp) into subsets based on K-mer frequency in sequence assembly to a low-diversity acid mine drainage (AMD) microbial community and, by integrating with an additional metatranscriptomic assembly, successfully obtained 11 draft genomes most of which represent yet uncultured and/or rare taxa (relative abundance <1%). We reportmore » the first genome of a naturally occurring Ferrovum population (relative abundance >90%) and its metabolic potentials and gene expression profile, providing initial molecular insights into the ecological role of these lesser known, but potentially important, microorganisms in the AMD environment. Gene transcriptional analysis of the active taxa revealed major metabolic capabilities executed in situ, including carbon- and nitrogen-related metabolisms associated with syntrophic interactions, iron and sulfur oxidation, which are key in energy conservation and AMD generation, and the mechanisms of adaptation and response to the environmental stresses (heavy metals, low pH and oxidative stress). Remarkably, nitrogen fixation and sulfur oxidation were performed by the rare taxa, indicating their critical roles in the overall functioning and assembly of the AMD community. Finally, our study demonstrates the potential of the ‘divide and conquer’ strategy in high-throughput sequencing data assembly for genome reconstruction and functional partitioning analysis of both dominant and rare species in natural microbial assemblages.« less

Role of microbial activity in Fe(III) hydroxysulfate mineral transformations in an acid mine drainage-impacted site from the Dabaoshan Mine.

PubMed

Bao, Yanping; Guo, Chuling; Lu, Guining; Yi, Xiaoyun; Wang, Han; Dang, Zhi

2018-03-01

Fe(III) hydroxysulfate minerals are secondary minerals commonly found in acid mine drainage (AMD) sites and have a major impact on water and soil quality in these environments. While previous studies showed that the Fe(III) hydroxysulfate mineral transformation could be mediated by some bacterial strains under laboratory conditions, the role of indigenous microbial activity in Fe(III) hydroxysulfate mineral transformation in natural environment has received little attention. In this study, microcosms were constructed with AMD-affected river water and sediment from the Dabaoshan Mine that was either left unamended or enriched with nutrients (lactate, nitrogen, and phosphorus (LNP)) and biosynthetic minerals (schwertmannite or jarosite). The results show that microbial activity played a decisive role in the mineralogical transformation of schwertmannite/jarosite in the AMD-contaminated site when organic carbon was available. The accumulation of Fe(II) and sulfide in microcosms amended with LNP indicates that schwertmannite/jarosite transformation is mediated by microbial reduction. XRD, SEM and FTIR analyses suggest that schwertmannite was completely transformed to goethite in the Sch-LNP microcosms at the end of their incubation. Jarosite in the Jar-LNP microcosms was also transformed to goethite, but at a much slower rate than schwertmannite. Bacterial community analysis reveals that the stimulated indigenous bacteria promote the mineralogical transformation of schwertmannite/jarosite. Most of these bacteria, including Geobacter, Desulfosporosinus, Geothrix, Desulfurispora, Desulfovibrio, and Anaeromyxobacter, are known to reduce iron and/or sulfate. The mineralogical transformation of schwertmannite and jarosite exerts significant control on the geochemistry of AMD-contaminated systems. Copyright © 2018 Elsevier B.V. All rights reserved.

Ecological roles of dominant and rare prokaryotes in acid mine drainage revealed by metagenomics and metatranscriptomics

DOE PAGES

Hua, Zheng-Shuang; Han, Yu-Jiao; Chen, Lin-Xing; ...

2014-11-07

Here we report that high-throughput sequencing is expanding our knowledge of microbial diversity in the environment. Still, understanding the metabolic potentials and ecological roles of rare and uncultured microbes in natural communities remains a major challenge. To this end, we applied a ‘divide and conquer’ strategy that partitioned a massive metagenomic data set (>100 Gbp) into subsets based on K-mer frequency in sequence assembly to a low-diversity acid mine drainage (AMD) microbial community and, by integrating with an additional metatranscriptomic assembly, successfully obtained 11 draft genomes most of which represent yet uncultured and/or rare taxa (relative abundance <1%). We reportmore » the first genome of a naturally occurring Ferrovum population (relative abundance >90%) and its metabolic potentials and gene expression profile, providing initial molecular insights into the ecological role of these lesser known, but potentially important, microorganisms in the AMD environment. Gene transcriptional analysis of the active taxa revealed major metabolic capabilities executed in situ, including carbon- and nitrogen-related metabolisms associated with syntrophic interactions, iron and sulfur oxidation, which are key in energy conservation and AMD generation, and the mechanisms of adaptation and response to the environmental stresses (heavy metals, low pH and oxidative stress). Remarkably, nitrogen fixation and sulfur oxidation were performed by the rare taxa, indicating their critical roles in the overall functioning and assembly of the AMD community. Finally, our study demonstrates the potential of the ‘divide and conquer’ strategy in high-throughput sequencing data assembly for genome reconstruction and functional partitioning analysis of both dominant and rare species in natural microbial assemblages.« less

EFFECT OF pH, IONIC STRENGTH, DISSOLVED ORGANIC CARBON, TIME, AND PARTICLE SIZE ON METALS RELEASE FROM MINE DRAINAGE IMPACTED STREAMBED SEDIMENTS

EPA Science Inventory

Acid-mine drainage (AMD) input to a stream typically results in the stream having a reduced pH, increased concentrations of metals and salts, and decreased biological productivity. Removal and/or treatment of these AMD sources is desired to return the impacted stream(s) to initi...

Pyrolusite Process® to remove acid mine drainage contaminants from Kimble Creek in Ohio: A pilot study

Treesearch

Shiv Hiremath; Kirsten Lehtoma; Mike Nicklow; Gary Willison

2013-01-01

The Kimble Creek abandoned coal mine site, located on Wayne National Forest in southeastern Ohio, is among several abandoned coal mine sites that have been responsible for the acid mine drainage (AMD) polluting ground and surface water. Materials released by AMD include iron, aluminum, manganese, other hazardous substances, and acidity that are harmful to aquatic life...

As(III) and As(V) removal from the aqueous phase via adsorption onto acid mine drainage sludge (AMDS) alginate beads and goethite alginate beads.

PubMed

Lee, Hongkyun; Kim, Dohyeong; Kim, Jongsik; Ji, Min-Kyu; Han, Young-Soo; Park, Young-Tae; Yun, Hyun-Shik; Choi, Jaeyoung

2015-07-15

Acid mine drainage sludge (AMDS) is a solid waste generated following the neutralization of acid mine drainage (AMD). This material entrapped in calcium alginate was investigated for the sorption of As(III) and As(V). Three different adsorbent materials were prepared: AMDS alginate beads (AABs), goethite alginate beads (GABs), and pure alginate beads. The effects of pH and the adsorption kinetics were investigated, and the adsorption isotherms were also evaluated. The optimum pH range using the AABs was determined to be within 2-10 for As(III) and 2-9 for As(V). Adsorption equilibrium data were evaluated using the Langmuir isotherm model, and the maximum adsorption capacity qmax was 18.25 and 4.97 mg g(-1) for As(III) on AAB and GAB, respectively, and 21.79 and 10.92 mg g(-1) for As(V) on AAB and GAB, respectively. The adsorption of As(III) and As(V) was observed to follow pseudo-second order kinetics. The As K-edge X-ray absorption near-edge structure (XANES) revealed that the adsorbed As(III) on the AABs was oxidized to As(V) via manganese oxide in the AMDS. Copyright © 2015 Elsevier B.V. All rights reserved.

Complete genome sequence of the bioleaching bacterium Leptospirillum sp. group II strain CF-1.

PubMed

Ferrer, Alonso; Bunk, Boyke; Spröer, Cathrin; Biedendieck, Rebekka; Valdés, Natalia; Jahn, Martina; Jahn, Dieter; Orellana, Omar; Levicán, Gloria

2016-03-20

We describe the complete genome sequence of Leptospirillum sp. group II strain CF-1, an acidophilic bioleaching bacterium isolated from an acid mine drainage (AMD). This work provides data to gain insights about adaptive response of Leptospirillum spp. to the extreme conditions of bioleaching environments. Copyright © 2016 Elsevier B.V. All rights reserved.

Insights into the diversity of eukaryotes in acid mine drainage biofilm communities.

PubMed

Baker, Brett J; Tyson, Gene W; Goosherst, Lindsey; Banfield, Jillian F

2009-04-01

Microscopic eukaryotes are known to have important ecosystem functions, but their diversity in most environments remains vastly unexplored. Here we analyzed an 18S rRNA gene library from a subsurface iron- and sulfur-oxidizing microbial community growing in highly acidic (pH < 0.9) runoff within the Richmond Mine at Iron Mountain (northern California). Phylogenetic analysis revealed that the majority (68%) of the sequences belonged to fungi. Protists falling into the deeply branching lineage named the acidophilic protist clade (APC) and the class Heterolobosea were also present. The APC group represents kingdom-level novelty, with <76% sequence similarity to 18S rRNA gene sequences of organisms from other environments. Fluorescently labeled oligonucleotide rRNA probes were designed to target each of these groups in biofilm samples, enabling abundance and morphological characterization. Results revealed that the populations vary significantly with the habitat and no group is ubiquitous. Surprisingly, many of the eukaryotic lineages (with the exception of the APC) are closely related to neutrophiles, suggesting that they recently adapted to this extreme environment. Molecular analyses presented here confirm that the number of eukaryotic species associated with the acid mine drainage (AMD) communities is low. This finding is consistent with previous results showing a limited diversity of archaea, bacteria, and viruses in AMD environments and suggests that the environmental pressures and interplay between the members of these communities limit species diversity at all trophic levels.

Relationships between sources of acid mine drainage and the hydrochemistry of acid effluents during rainy season in the Iberian Pyrite Belt.

PubMed

Pérez-Ostalé, E; Grande, J A; Valente, T; de la Torre, M L; Santisteban, M; Fernández, P; Diaz-Curiel, J

2016-01-01

In the Iberian Pyrite Belt (IPB), southwest Spain, a prolonged and intense mining activity of more than 4,500 years has resulted in almost a hundred mines scattered through the region. After years of inactivity, these mines are still causing high levels of hydrochemical degradation in the fluvial network. This situation represents a unique scenario in the world, taking into consideration its magnitude and intensity of the contamination processes. In order to obtain a benchmark regarding the degree of acid mine drainage (AMD) pollution in the aquatic environment, the relationship between the areas occupied by the sulfide mines and the characteristics of the respective effluents after rainfall was analysed. The methodology developed, which includes the design of a sampling network, analytical treatment and cluster analysis, is a useful tool for diagnosing the contamination level by AMD in an entire metallogenic province, at the scale of each mining group. The results presented the relationship between sulfate, total dissolved solids and electrical conductivity, as well as other parameters that are typically associated with AMD and the major elements that compose the polymetallic sulfides of IPB. This analysis also indicates the low level of proximity between the affectation area and the other variables.

Effect of Phospholipid on Pyrite Oxidation and Microbial Communities under Simulated Acid Mine Drainage (AMD) Conditions.

PubMed

Pierre Louis, Andro-Marc; Yu, Hui; Shumlas, Samantha L; Van Aken, Benoit; Schoonen, Martin A A; Strongin, Daniel R

2015-07-07

The effect of phospholipid on the biogeochemistry of pyrite oxidation, which leads to acid mine drainage (AMD) chemistry in the environment, was investigated. Metagenomic analyses were carried out to understand how the microbial community structure, which developed during the oxidation of pyrite-containing coal mining overburden/waste rock (OWR), was affected by the presence of adsorbed phospholipid. Using columns packed with OWR (with and without lipid adsorption), the release of sulfate (SO4(2-)) and soluble iron (FeTot) was investigated. Exposure of lipid-free OWR to flowing pH-neutral water resulted in an acidic effluent with a pH range of 2-4.5 over a 3-year period. The average concentration of FeTot and SO4(2-) in the effluent was ≥20 and ≥30 mg/L, respectively. In contrast, in packed-column experiments where OWR was first treated with phospholipid, the effluent pH remained at ∼6.5 and the average concentrations of FeTot and SO4(2-) were ≤2 and l.6 mg/L, respectively. 16S rDNA metagenomic pyrosequencing analysis of the microbial communities associated with OWR samples revealed the development of AMD-like communities dominated by acidophilic sulfide-oxidizing bacteria on untreated OWR samples, but not on refuse pretreated with phospholipid.

Influence of elevated temperature and acid mine drainage on mortality of the crayfish Cambarus bartonii

USGS Publications Warehouse

Hartman, K.J.; Hom, C.D.; Mazik, P.M.

2010-01-01

Effects of elevated temperature and acid mine drainage (AMD) on crayfish mortality were investigated in the Stony River, Grant County, West Virginia. During summers 2003 and 2004, four-week in situ bioassays were performed along a thermal and AMD gradient with the native crayfish Cambarus bartonii. Crayfish mortality was analyzed in conjunction with temperature and AMD related variables (pH, specific conductivity). Mortality was significantly higher (48-88%) at sites with high temperatures during 2003 (max = 33.0??C), but no significant differences were observed in 2004 (max = 32.0??C). Temperatures were higher in 2003 than 2004 due to increased discharge from a cooling reservoir flowing into the river. Additionally, duration of high temperature was approximately four days in 2003 as compared with only one day in 2004. No significant relationship between acid mine drainage variables and crayfish mortality was apparent.

Application of acid mine drainage for coagulation/flocculation of microalgal biomass.

PubMed

Salama, El-Sayed; Kim, Jung Rae; Ji, Min-Kyu; Cho, Dong-Wan; Abou-Shanab, Reda A I; Kabra, Akhil N; Jeon, Byong-Hun

2015-06-01

A novel application of acid mine drainage (AMD) for biomass recovery of two morphologically different microalgae species with respect to AMD dosage, microalgal cell density and pH of medium was investigated. Optimal flocculation of Scenedesmus obliquus and Chlorella vulgaris occurred with 10% dosage of AMD at an initial pH 9 for both 0.5 and 1.0 g/L cell density. The flocculation efficiency was 89% for S. obliquus and 93% for C. vulgaris. Zeta potential (ZP) was increased from -10.66 to 1.77 and -13.19 to 1.33 for S. obliquus and C. vulgaris, respectively. Scanning electron microscope with energy-dispersive X-ray of the microalgae floc confirmed the sweeping floc formation mechanism upon the addition of AMD. Application of AMD for the recovery of microalgae biomass is a cost-effective method, which might further allow reuse of flocculated medium for algal cultivation, thereby contributing to the economic production of biofuel from microalgal biomass. Copyright © 2015 Elsevier Ltd. All rights reserved.

Removal of phosphorus from wastewater using ferroxysorb sorption media produced from amd sludge

USGS Publications Warehouse

Sibrell, P.L.; Tucker, T.W.; Kehler, T.; Fletcher, J.W.

2008-01-01

Treatment of acid mine drainage (AMD), whether with lime, limestone, caustic or simple aeration, nearly always results in generation of a metal hydroxide sludge. Disposal of the sludge often constitutes a significant fraction of the operating cost for the AMD treatment plant. Research at the USGS - Leetown Science Center has shown that AMD sludge, with its high content of aluminum and iron oxides, has a high affinity of phosphorus (P). Anthropogenic sources of P are associated with eutrophication and degradation of aquatic environments, resulting in anoxic dead zones in certain sensitive waterways. In this paper, we describe a method of converting the AMD sludge from a liability into an asset - Ferroxysorb P removal media - which can be used to remove excess P from wastewater. Three different Ferroxysorb media samples were produced from differing AMD sources and tested for P removal. Adsorption isotherms confirmed that the media had a high sorption capacity for P, as high as 19,000 mg/kg. The technology was demonstrated at an active fish hatchery, where the media remained in service for over three months without stripping or regeneration. Over that period of time, the calculated P removal was 50%, even at a very low influent P concentration of 60 parts per billion. In summary, use of the AMD-derived Ferroxysorb sorption media will reduce AMD treatment costs while at the same time helping to resolve the pressing environmental issue of eutrophication and degradation of sensitive waterways.

The Revival of a Failed Constructed Wetland Treating of a High Fe Load AMD

Treesearch

A.D. Karathanasis; C.D. Barton

1999-01-01

Acid mine drainage (AMD) from abandoned mines has significantly impaired water quality in eastern Kentucky. A small surface flow wetland constructed in 1989 to reduce AMD effects and subsequently failed after six months of operation was renovated by incorporating anoxic limestone drains (ALDs) and anaerobic subsurface drains promoting vertical flow through successive...

Spatial Variations In The Fate And Transport Of Metals In A Mining-Influenced Stream, North Fork Clear Creek, Colorado

EPA Science Inventory

North Fork Clear Creek (NFCC) receives acid-mine drainage (AMD) from multiple abandoned mines in the Clear Creek Watershed. Point sources of AMD originate In the Black Hawk/Central City region of the stream. Water chemistry also is influenced by several non-point sources of AMD,...

Impact of Legacy Surface Mining on Water Quality in the Lake Harris Watershed, Tuscaloosa County, Alabama.

NASA Astrophysics Data System (ADS)

Donahoe, R. J.; Hawkins, P. D.

2017-12-01

The Lake Harris watershed was the site of legacy surface mining of coal conducted from approximately 1969 to 1976. The mine site was abandoned and finally reclaimed in 1986. Water quality in the stream draining the mined area is still severely impacted by acid mine drainage (AMD), despite the reclamation effort. Lake Harris is used as a source of industrial water, but shows no negative water quality effects from the legacy mining activities despite receiving drainage from the AMD-impacted stream. Water samples were collected monthly between October 2016 and September 2017 from a first-order stream impacted by acid mine drainage (AMD), a nearby first-order control stream, and Lake Harris. Stream water chemistry was observed to vary both spatially and seasonally, as monitored at five sample stations in each stream over the study period. Comparison of the two streams shows the expected elevated concentrations of AMD-indicator solutes (sulfate and iron), as well as significant increases in conductivity and acidity for the stream draining the reclaimed mine site. In addition, dramatic (1-2 orders of magnitude) increases in major element (Al, Ca, Mg, K), minor element (Mn, Sr) and trace element (Co, Ni) concentrations are also observed for the AMD-impacted stream compared to the control stream. The AMD-impacted stream also shows elevated (2-4 times) levels of other stream water solutes (Cl, Na, Si, Zn), compared to the control stream. As the result of continuing AMD input, the stream draining the reclaimed mine site is essentially sterile, in contrast to the lake and control stream, which support robust aquatic ecosystems. A quantitative model, constrained by isotopic data (δD and δ18O), will be presented that seeks to explain the observed temporal differences in water quality for the AMD-impacted stream as a function of variable meteoric water, groundwater, and AMD inputs. Similar models may be developed for other AMD-impacted streams to better understand and predict temporal variations in water quality parameters and their effect on aquatic ecosystems.

Utilization of AMD sludges from the anthracite region of Pennsylvania for removal of phosphorus from wastewater

USGS Publications Warehouse

Sibrell, P.L.; Cravotta, C.A.; Lehman, W.G.; Reichert, W.

2010-01-01

Excess phosphorus (P) inputs from human sewage, animal feeding operations, and nonpoint source discharges to the environment have resulted in the eutrophication of sensitive receiving bodies of water such as the Great Lakes and Chesapeake Bay. Phosphorus loads in wastewater discharged from such sources can be decreased by conventional treatment with iron and aluminum salts but these chemical reagents are expensive or impractical for many applications. Acid mine drainage (AMD) sludges are an inexpensive source of iron and aluminum hydrous oxides that could offer an attractive alternative to chemical reagent dosing for the removal of P from local wastewater. Previous investigations have focused on AMD sludges generated in the bituminous coal region of western Pennsylvania, and confirmed that some of those sludges are good sorbents for P over a wide range of operating conditions. In this study, we sampled sludges produced by AMD treatment at six different sites in the anthracite region of Pennsylvania for potential use as P sequestration sorbents. Sludge samples were dried, characterized, and then tested for P removal from water. In addition, the concentrations of acid-extractable metals and other impurities were investigated. Test results revealed that sludges from four of the sites showed good P sorption and were unlikely to add contaminants to treated water. These results indicate that AMD sludges could be beneficially used to sequester P from the environment, while at the same time decreasing the expense of sludge disposal.

Response of macroinvertebrate communities to remediation-simulating conditions in Pennsylvania streams influenced by acid mine drainage

USGS Publications Warehouse

Ross, R.M.; Long, E.S.; Dropkin, D.S.

2008-01-01

We compared naturally alkaline streams with limestone lithology to freestone streams with and without acid mine drainage (AMD) to predict benthic macroinvertebrate community recovery from AMD in limestone-treated watersheds. Surrogate-recovered (limestone) and, in many cases, freestone systems had significantly higher macroinvertebrate densities; diversity; taxa richness; Ephemeroptera, Plecoptera, and Trichoptera (EPT) taxa; EPT/chironomid ratios; scraper/collector - gatherer ratios; herbivores; collector - filterers; and scrapers. AMD-influenced systems had significantly greater numbers of Diptera and collector - gatherers. An entire trophic level (herbivores) was 'restored' in surrogate-recovered streams, which also showed greater trophic specialization. Indicator analysis identified seven taxa (within Crustacea, Diptera, Nematoda, Trichoptera, and Ephemeroptera) as significant indicators of limestone systems and six taxa (within Ephemeroptera, Plecoptera, Tricoptera, Coleoptera, and Mollusca) as significant freestone indicators, all useful as biological indicators of recovery from AMD. ?? Springer Science+Business Media B.V. 2007.

Localized effects of coal mine drainage on fish assemblages in a Cumberland Plateau stream in Tennessee

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schorr, M.S.; Backer, J.C.

2006-03-15

The upper watershed of North Chickamauga Creek (NCC), a fourth-order tributary to the Tennessee River, Tennessee, has been impacted by decades of acid mine drainage (AMD) from abandoned coal mines. We assessed fish assemblages, pH, conductivity, and sediment coverage at 12 study reaches (six AMD sites and six reference sites) in the Cumberland Plateau region of the NCC system, May-September 1998. Stream pH increased (3.6 to 6.0) and conductivity decreased (296 to 49 {mu}S/cm) downstream of the AMD-impacted area; however, no discernable gradient was observed in sediment cover. Elevated conductivity at AMD-impacted sites reflected increased concentrations of dissolved metals andmore » other inorganic ions. Reference sites exhibited higher pH (6.0-6.4) and lower conductivity (13-28 {mu}S/cm). Acidified reaches were characterized by low fish species richness and abundance; no fish were observed at sites where the mean pH was {lt} 5. Centrarchids (mostly bluegill (Lepomis macrochirus) and green sunfish (L. cyanellus)) comprised {gt} 90 % of the catch at AMD sites, whereas cypriniids (creek chub (Semotilus atromaculatus) and blacknose dace (Rhinichthys atratulus)) accounted for {gt} 90 % of the catch at reference sites. Findings from this study document the negative effects of acid drainage from coal mines on fish assemblages in a Cumberland Plateau stream.« less

Recovery of Rare Earth Elements and Yttrium from Passive-Remediation Systems of Acid Mine Drainage.

PubMed

Ayora, Carlos; Macías, Francisco; Torres, Ester; Lozano, Alba; Carrero, Sergio; Nieto, José-Miguel; Pérez-López, Rafael; Fernández-Martínez, Alejandro; Castillo-Michel, Hiram

2016-08-02

Rare earth elements and yttrium (REY) are raw materials of increasing importance for modern technologies, and finding new sources has become a pressing need. Acid mine drainage (AMD) is commonly considered an environmental pollution issue. However, REY concentrations in AMD can be several orders of magnitude higher than in naturally occurring water bodies. With respect to shale standards, the REY distribution pattern in AMD is enriched in intermediate and valuable REY, such as Tb and Dy. The objective of the present work is to study the behavior of REY in AMD passive-remediation systems. Traditional AMD passive remediation systems are based on the reaction of AMD with calcite-based permeable substrates followed by decantation ponds. Experiments with two columns simulating AMD treatment demonstrate that schwertmannite does not accumulate REY, which, instead, are retained in the basaluminite residue. The same observation is made in two field-scale treatments from the Iberian Pyrite Belt (IPB, southwest Spain). On the basis of the amplitude of this process and on the extent of the IPB, our findings suggest that the proposed AMD remediation process can represent a modest but suitable REY source. In this sense, the IPB could function as a giant heap-leaching process of regional scale in which rain and oxygen act as natural driving forces with no energy investment. In addition to having environmental benefits of its treatment, AMD is expected to last for hundreds of years, and therefore, the total reserves are practically unlimited.

Lipid Biomarkers and Carbon Isotope Ratios of Lipids Isolated from Acid Mine Drainage Biofilms: Dual Biosignatures for Eukaryotic Evolution and Oxygenation of Primitive Earth

NASA Astrophysics Data System (ADS)

Dasgupta, S.; Fang, J.; Zhang, L.; Li, J.

2012-12-01

Lipid analysis and carbon isotope ratios (δ13C) of lipids in biofilms in an acid mine drainage site (AMD) site in western Indiana revealed unique biogeochemical signatures of microeukaryotes, never recorded before. Dominance of photosynthetic microeukaryote Euglena was indicated by the detection of abundant phytadiene, phytol, phytanol, polyunsaturated n-alkenes, polyunsaturated fatty acids, short-chain (C25-32) wax esters (WE), ergosterol, and tocopherols. The WE were probably synthesized in mitochondria under anoxic conditions by the reverse β-oxidation pathway, whereas the sterols (ergosterol and ergosta-7,22-dien-3β-ol) were likely synthesized in the cytosol in the presence of molecular oxygen. The dual aerobic and anaerobic biosynthetic pathways of Euglena may be a response to survive the recurring anoxic and oxic conditions in primitive Earth, whereby microeukaryotes retained this mechanism of conserved compartmentalization within their physiology to evolve and diversify in extreme conditions. Hydrocarbons, including n-alkenes, phytadienes, and wax esters showed heavy δ13C values than usual. The primary cause for the 13C-enrichment can be attributed to a CO2-limiting system that exists in the AMD, which is further regulated by the pH of the AMD. Floating biofilms BF2, 4, and 6 showed more depleted δ13C values for phytadienes and n-alkenes (average of -23.6‰) as compared to benthic biofilm BF5 (average of -20.8‰), indicating that physiology plays an important role in isotopic discrimination. 13C-enriched values of the esters could result from kinetic isotope effects at two branch points (pyruvate and/or acetyl CoA) in the biosynthetic pathway. Our understanding of biogeochemical conditions in this AMD environment would allow us to identify unique sets of biosignatures that can act as a proxy in deciphering the links between eukaryotic evolutions, oxygenation of the early atmosphere, formation of BIF, and possibly iron-rich extraterrestrial environments.

Sulphates Removal from Acid Mine Drainage

NASA Astrophysics Data System (ADS)

Luptáková, Alena; Mačingová, Eva; Kotuličová, Ingrida; Rudzanová, Dominika

2016-10-01

Acid mine drainage (AMD) are a worldwide problem leading to ecological destruction in river basins and the contamination of water sources. AMD are characterized by low pH and high content of heavy metals and sulphates. In order to minimize negative impacts of AMD appropriate treatment techniques has to be chosen. Treatment processes are focused on neutralizing, stabilizing and removing pollutants. From this reason efficient and environmental friendly methods are needed to be developed in order to reduce heavy metals as well as sulphates. Various methods are used for remediation of acid mine drainage, but any of them have been applied under commercial-scale conditions. Their application depends on geochemical, technical, natural, financial, and other factors. The aim of the present work was to interpret the study of biological methods for sulphates removal from AMD out-flowing from the shaft Pech of the deposit Smolmk in Slovak Republic. In the experimental works AMD were used after removal of heavy metals by precipitation and sorption using the synthetic sorbent Slovakite. The base of the studied method for the sulphates elimination was the anaerobic bacterial sulphate reduction using sulphate-reducing bacteria (SRB) genera Desulfovibrio. SRB represent a group of bacteria that uses sulphates as a terminal electron acceptor for their metabolism. These bacteria realize the conversion of sulphate to hydrogen sulphide under anaerobic conditions. For the purposes of experiments a few variants of the selective medium DSM-63 culture media were used in term of the sulphates and sodium lactate contents in the selective medium as well as sulphates in the studied AMD.

Extracellular Electron Transfer and Survival Strategies in Acid Mine Drainage Impacted Soils

NASA Astrophysics Data System (ADS)

Gorby, Y. A.; Senko, J.

2011-12-01

Acid mine drainage (AMD) is a prominent and increasing problem in the greater Appalachian region of the United States and throughout the world. Recognition of the importance of extracellular electron transfer (EET) in microbial communities has provided a fertile research environment for multidisciplinary collaborations to emerge and effectively address complex questions with important environmental implications. Our research focuses on the components, strategies and mechanisms of EET in soil systems impacted by AMD and extends to other biogeochemical systems typified by steep redox gradients. Organisms within acid mine drainage use Fe(II) as their primary electron donor and couple Fe(II) oxidation to the reduction of oxygen as the terminal electron acceptor. Biogenic minerals formed by this process completely encase microbes in think deposits that would seem to limit diffusion of both Fe(II) and O2 for access by the organisms. We have developed methods for catalytically removing biogenic minerals revealing microorganisms and a fine network of filamentous extracellular material. Here we present a status report of our efforts to characterize the molecular and electronic properties of these filaments and to address the hypothesis that at least some of these filaments are electrically conductive microbial nanowires that facilitate electron transfer reactions within this complex biogeochemical system.

Pollution in acid mine drainage from mine tailings in Svalbard Norwegian Arctic

NASA Astrophysics Data System (ADS)

Holm, E. B.; Brandvik, P. J.; Steinnes, E.

2003-05-01

Throughout the summer season of 2000 samples of acid mine drainage (AMD) were collected from areas below tailing deposits from the coal mining in Svalbard, Norwegian Arctic. The water was analysed for pH, oxygen, conductivity, 9 sulfate and various metals. Oxygen, pH and conductivity were measured by standard electrodes, sulphate was determined gravimetrically and metals were determined by flame/graphite furnace AAS. The AMD was found to contain heavy metals and sulphate in high concentrations, causing damage to the local tundra vegetation. Large spatial variation however was observed in pH (2.5-9.5) as well as in metal concentrations in the AMD, indicating strongly inhomogeneous distribution of sulphide minerais in the tailing deposits.

GeoChip-Based Analysis of the Functional Gene Diversity and Metabolic Potential of Microbial Communities in Acid Mine Drainage▿ †

PubMed Central

Xie, Jianping; He, Zhili; Liu, Xinxing; Liu, Xueduan; Van Nostrand, Joy D.; Deng, Ye; Wu, Liyou; Zhou, Jizhong; Qiu, Guanzhou

2011-01-01

Acid mine drainage (AMD) is an extreme environment, usually with low pH and high concentrations of metals. Although the phylogenetic diversity of AMD microbial communities has been examined extensively, little is known about their functional gene diversity and metabolic potential. In this study, a comprehensive functional gene array (GeoChip 2.0) was used to analyze the functional diversity, composition, structure, and metabolic potential of AMD microbial communities from three copper mines in China. GeoChip data indicated that these microbial communities were functionally diverse as measured by the number of genes detected, gene overlapping, unique genes, and various diversity indices. Almost all key functional gene categories targeted by GeoChip 2.0 were detected in the AMD microbial communities, including carbon fixation, carbon degradation, methane generation, nitrogen fixation, nitrification, denitrification, ammonification, nitrogen reduction, sulfur metabolism, metal resistance, and organic contaminant degradation, which suggested that the functional gene diversity was higher than was previously thought. Mantel test results indicated that AMD microbial communities are shaped largely by surrounding environmental factors (e.g., S, Mg, and Cu). Functional genes (e.g., narG and norB) and several key functional processes (e.g., methane generation, ammonification, denitrification, sulfite reduction, and organic contaminant degradation) were significantly (P < 0.10) correlated with environmental variables. This study presents an overview of functional gene diversity and the structure of AMD microbial communities and also provides insights into our understanding of metabolic potential in AMD ecosystems. PMID:21097602

Impact on sediments and water by release of copper from chalcopyrite bearing rock due to acidic mine drainage

NASA Astrophysics Data System (ADS)

Shukla, Anoop Kant; Pradhan, Manoj; Tiwari, Onkar Nath

2018-04-01

Mining activity causes transition of rock-mass from its original position in earth into open environment. The action of environmental elements such air, water, microorganisms leads to oxidation of minerals which constitute the rock. The oxidation of sulphide minerals in presence of moisture releases acidic mine discharge (AMD). The acidic nature of AMD causes leaching of metals from rock minerals. Dissolution of other minerals may occur upon reaction with AMD. Chalcopyrite (CuFeS2) undergoes oxidation in acidic condition releasing copper among other products. This study reveals contamination of copper in sediment samples and seepage water from the tailing dam of a large copper project in located in central India. Elevation was studied using GIS to ascertain to the topographic elevation of tailing dam area. It was located at relatively high altitude causing seepage to flow away from tailing dam. The seepage water from tailing dam was found to be acidic with mean pH value of 4.0 and elevated copper content. Similarly, sediments from seepage water flow displayed elevated copper concentration. The copper concentration in seepage water was found with a mean value of 10.73 mg/l. The sediments from seepage water flow also displayed elevated copper concentration with mean value of 26.92 g/kg. This indicates impact on sediments by release of copper due to acidic mine drainage.

DEMONSTRATION OF AN INTEGRATED, PASSIVE BIOLOGICAL TREATMENT PROCESS FOR AMD

EPA Science Inventory

An innovative, cost-effective, biological treatment process has been designed by MSE Technology Applications, Inc. to treat acid mine drainage (AMD). A pilot-scale demonstration is being conducted under the Mine Waste Technology Program using water flowing from an abandoned mine ...

Hyperspectral analysis for qualitative and quantitative features related to acid mine drainage at a remediated open-pit mine

NASA Astrophysics Data System (ADS)

Davies, G.; Calvin, W. M.

2015-12-01

The exposure of pyrite to oxygen and water in mine waste environments is known to generate acidity and the accumulation of secondary iron minerals. Sulfates and secondary iron minerals associated with acid mine drainage (AMD) exhibit diverse spectral properties in the ultraviolet, visible and near-infrared regions of the electromagnetic spectrum. The use of hyperspectral imagery for identification of AMD mineralogy and contamination has been well studied. Fewer studies have examined the impacts of hydrologic variations on mapping AMD or the unique spectral signatures of mine waters. Open-pit mine lakes are an additional environmental hazard which have not been widely studied using imaging spectroscopy. A better understanding of AMD variation related to climate fluctuations and the spectral signatures of contaminated surface waters will aid future assessments of environmental contamination. This study examined the ability of multi-season airborne hyperspectral data to identify the geochemical evolution of substances and contaminant patterns at the Leviathan Mine Superfund site. The mine is located 24 miles southeast of Lake Tahoe and contains remnant tailings piles and several AMD collection ponds. The objectives were to 1) distinguish temporal changes in mineralogy at a the remediated open-pit sulfur mine, 2) identify the absorption features of mine affected waters, and 3) quantitatively link water spectra to known dissolved iron concentrations. Images from NASA's AVIRIS instrument were collected in the spring, summer, and fall seasons for two consecutive years at Leviathan (HyspIRI campaign). Images had a spatial resolution of 15 meters at nadir. Ground-based surveys using the ASD FieldSpecPro spectrometer and laboratory spectral and chemical analysis complemented the remote sensing data. Temporal changes in surface mineralogy were difficult to distinguish. However, seasonal changes in pond water quality were identified. Dissolved ferric iron and chlorophyll-a concentrations were determined to be the major influences on pond water spectral variation.

Characterization of Fe(II) oxidizing bacterial activities and communities at two acidic Appalachian coalmine drainage-impacted sites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Senko, John M.; Wanjugi, Pauline; Lucas, Melanie

2008-06-12

We characterized the microbiologically mediated oxidative precipitation of Fe(II) from coalminederived acidic mine drainage (AMD) along flow-paths at two sites in northern Pennsylvania. At the Gum Boot site, dissolved Fe(II) was efficiently removed from AMD whereas minimal Fe(II) removal occurred at the Fridays-2 site. Neither site received human intervention to treat the AMD. Culturable Fe(II) oxidizing bacteria were most abundant at sampling locations along the AMD flow path corresponding to greatest Fe(II) removal and where overlying water contained abundant dissolved O2. Rates of Fe(II) oxidation determined in laboratory-based sediment incubations were also greatest at these sampling locations. Ribosomal RNA intergenicmore » spacer analysis and sequencing of partial 16S rRNA genes recovered from sediment bacterial communities revealed similarities among populations at points receiving regular inputs of Fe(II)-rich AMD and provided evidence for the presence of bacterial lineages capable of Fe(II) oxidation. A notable difference between bacterial communities at the two sites was the abundance of Chloroflexi-affiliated 16S rRNA gene sequences in clone libraries derived from the Gum Boot sediments. Our results suggest that inexpensive and reliable AMD treatment strategies can be implemented by mimicking the conditions present at the Gum Boot field site.« less

USE OF HYDROGEN RESPIROMETRY TO DETERMINE METAL TOXICITY TO SULFATE REDUCING BACTERIA

EPA Science Inventory

Acid mine drainage (AMD), an acidic metal-bearing wastewater poses a severe pollution problem attributed to post-mining activities. The metals (metal sulfates) encountered in AMD and considered of concern for risk assessment are: arsenic, cadmium, aluminum, manganese, iron, zinc ...

LIME TREATMENT LAGOONS TECHNOLOGY FOR TREATING ACID MINE DRAINAGE FROM TWO MINING SITES

EPA Science Inventory

Runoff and drainage from active and inactive mines are someof the most environmentally damaging land uses i the US. Acid Mine drainage (AMD) from mining sites across the country requires treatment because of high metal concentrations that exceed regulatory standards for safe disc...

Mycogenic Mn(II) oxidation promotes remediation of acid mine drainage and other anthropogenically impacted environments

NASA Astrophysics Data System (ADS)

Santelli, C. M.; Chaput, D.; Hansel, C. M.; Burgos, W. D.

2014-12-01

Manganese is a pollutant in worldwide environments contaminated with metals and organics, such as acid mine drainage (AMD), freshwater ponds, and agricultural waste storage sites. Microorganisms contribute to the removal of dissolved Mn compounds in the environment by promoting Mn(II) oxidation reactions. The oxidation of Mn(II) results in the precipitation of sparingly soluble Mn(IV) oxide minerals, effectively removing the metal from the aqueous milieu (e.g., groundwater or wastewater streams). In recent years, our research has identified a diversity of Mn(II)-oxidizing fungi inhabiting these polluted environments, however their overall contribution to the remediation process in situ remains poorly understood. Here we present results of culture-based and Next Generation Sequencing (NGS) studies in AMD treatment systems actively remediating Mn and other metals where we profile the bacterial, fungal, algal and archaeal communities to determine the overall community diversity and to establish the relative abundance of known Mn(II) oxidizers. A variety of treatment systems with varying Mn-removal efficiencies were sampled to understand the relationship between remediation efficiency and microbial community composition and activity. Targeted-amplicon sequencing of DNA and RNA of the 16S rRNA genes (bacteria and archaea), 23S rRNA genes (algae) and ITS region (fungi) was performed using both 454 pyrosequencing and Illumina platforms. Results showed that only the fungal taxonomic profiles significantly differed between sites that removed the majority of influent Mn and those that did not. Specifically, Ascomycota (which include known Mn(II) oxidizers isolated from these treatment systems) dominated greater efficiency systems whereas less efficient systems were dominated by Basidiomycota. Furthermore, known Mn(II) oxidizers accounted for only a minor proportion of bacterial sequences but a far greater proportion of fungal sequences. These culture-independent studies lend further evidence to numerous culture-based studies (of AMD remediation systems here, as well as a variety of other metal-rich systems) that establish Mn(II)-oxidizing fungi as important contributors to the remediation of Mn, and likely other metals, in metal polluted environments.

Efficient Low-pH Iron Removal by a Microbial Iron Oxide Mound Ecosystem at Scalp Level Run.

PubMed

Grettenberger, Christen L; Pearce, Alexandra R; Bibby, Kyle J; Jones, Daniel S; Burgos, William D; Macalady, Jennifer L

2017-04-01

Acid mine drainage (AMD) is a major environmental problem affecting tens of thousands of kilometers of waterways worldwide. Passive bioremediation of AMD relies on microbial communities to oxidize and remove iron from the system; however, iron oxidation rates in AMD environments are highly variable among sites. At Scalp Level Run (Cambria County, PA), first-order iron oxidation rates are 10 times greater than at other coal-associated iron mounds in the Appalachians. We examined the bacterial community at Scalp Level Run to determine whether a unique community is responsible for the rapid iron oxidation rate. Despite strong geochemical gradients, including a >10-fold change in the concentration of ferrous iron from 57.3 mg/liter at the emergence to 2.5 mg/liter at the base of the coal tailings pile, the bacterial community composition was nearly constant with distance from the spring outflow. Scalp Level Run contains many of the same taxa present in other AMD sites, but the community is dominated by two strains of Ferrovum myxofaciens , a species that is associated with high rates of Fe(II) oxidation in laboratory studies. IMPORTANCE Acid mine drainage pollutes more than 19,300 km of rivers and streams and 72,000 ha of lakes worldwide. Remediation is frequently ineffective and costly, upwards of $100 billion globally and nearly $5 billion in Pennsylvania alone. Microbial Fe(II) oxidation is more efficient than abiotic Fe(II) oxidation at low pH (P. C. Singer and W. Stumm, Science 167:1121-1123, 1970, https://doi.org/10.1126/science.167.3921.1121). Therefore, AMD bioremediation could harness microbial Fe(II) oxidation to fuel more-cost-effective treatments. Advances will require a deeper understanding of the ecology of Fe(II)-oxidizing microbial communities and the factors that control their distribution and rates of Fe(II) oxidation. We investigated bacterial communities that inhabit an AMD site with rapid Fe(II) oxidation and found that they were dominated by two operational taxonomic units (OTUs) of Ferrovum myxofaciens , a taxon associated with high laboratory rates of iron oxidation. This research represents a step forward in identifying taxa that can be used to enhance cost-effective AMD bioremediation. Copyright © 2017 American Society for Microbiology.

Gill lesions and death of bluegill in an acid mine drainage mixing zone

USGS Publications Warehouse

Henry, T.B.; Irwin, E.R.; Grizzle, J.M.; Brumbaugh, W.G.; Wildhaber, M.L.

2001-01-01

The toxicity of an acid mine drainage (AMD) mixing zone was investigated by placing bluegill (Lepomis macrochirus) at the confluence of a stream contaminated by AMD and a stream having neutral pH. A mixing channel receiving water from both streams was assembled in the field, during July and October 1996, to determine the toxicity of freshly mixed and aged water (2.9–7.5 min). The AMD stream had elevated concentrations of Al and Fe, which precipitated upon mixing, and of Mn, which did not precipitate in the mixing zone. Fish exposed to freshly mixed water had higher mortality than fish exposed to water after aging. Precipitating Al, but not Fe, accumulated on the gills of bluegill, and accumulation was more rapid early during the mixing process than after aging. Fish exposed for 3.5 h to freshly mixed water had hypertrophy and hyperplasia of gill filament and lamellar epithelial cells. Similar lesions were observed after 6.0 h in fish exposed to water aged after mixing. Results demonstrated that Al was the predominant metal accumulating on the gills of fish in this AMD mixing zone, and that mixing zones can be more toxic than AMD streams in equilibrium.

RECLAMATION OF TOXIC MINE WASTE UTILIZING SEWAGE SLUDGE CONTRARY CREEK DEMONSTRATION PROJECT

EPA Science Inventory

Three abandoned pyrite mines in central Virginia that had been inactive since 1923 contained about 12 denuded ha and caused severe acid mine drainage (AMD) in a small stream known as Contrary Creek. The AMD included heavy metals and rendered the stream virtually void of aquatic l...

Mineralogical controls on mobility of rare earth elements in acid mine drainage environments.

PubMed

Soyol-Erdene, T O; Valente, T; Grande, J A; de la Torre, M L

2018-08-01

Rare earth elements (REE) were analyzed in river waters, acid mine waters, and extracts of secondary precipitates collected in the Iberian Pyrite Belt. The obtained concentrations of the REE in river water and mine waters (acid mine drainage - AMD) were in the range of 0.57 μg/L (Lu) and 2579 μg/L (Ce), which is higher than previously reported in surface waters from the Iberian Pyrite Belt, but are comparable with previous findings from AMD worldwide. Total REE concentrations in river waters were ranged between 297 μg/L (Cobica River) and 7032 μg/L (Trimpancho River) with an average of 2468 μg/L. NASC (North American Shale Composite) normalized REE patterns for river and acid mine waters show clear convex curvatures in middle-REE (MREE) with respect to light- and heavy-REE. During the dissolution experiments of AMD-precipitates, heavy-REE and middle-REE generate the most enriched patterns in the solution. A small number of precipitates did not display MREE enrichment (an index Gd n /Lu n  < 1.0) in NASC normalized pattern and produced relatively lower REE concentrations in extracts. Additionally, very few samples, which mainly contained aluminum sulfates, e.g., pickeringite and alunogen, displayed light-REE enrichment relative to heavy-REE (HREE). In general, the highest retention of REE occurs in samples enriched in magnesium (epsomite or hexahydrite) and aluminum sulfates, mainly pickeringite. Copyright © 2018 Elsevier Ltd. All rights reserved.

Removal of phosphorus using AMD-treated lignocellulosic material

Treesearch

James S. Han; Soo-Hong Min; Yeong-Kwan Kim

2005-01-01

Excess nutrients, including phosphorus, can cause eutrophication in surface water and reservoirs. We tested the phosphate removal capacity of juniper fiber through isotherm, kinetic, column, and field tests. Heavy metals from an acid mine drainage (AMD) site were precipitated on the surface ofjuniper fiber. The modified fiber was tested in laboratory- caled batch and...

OPTIMIZATION OF A PULSED LIMESTONE BED REACTOR AT THE ARGO TUNNEL IN IDAHO SPRINGS, COLORADO

EPA Science Inventory

Acid Mine Drainage (AMD) is an unintended consequence of coal and metal mining that adversely affects thousands of miles of streams both in the eastern and western regions of the U.S. A novel AMD treatment process based on limestone based on limestone neutralization has been dev...

ACUTE TOXICITY OF HEAVY METALS TO ACETATE-UTILIZING MIXED CULTURES OF SULFATE-REDUCING BACTERIA: EC100 AND EC50

EPA Science Inventory

Acid mine drainage (AMD) from abandoned mines and acid mine pitlakes is an important environmental contaminant concern and usually contains appreciable concentrations of heavy metals. Since sulfate-reducing bacteria (SRB) are involved in the treatment of AMD, knowledge of acute m...

Acid neutralization within limestone sand reactors receiving coal mine drainage

USGS Publications Warehouse

Watten, B.J.; Sibrell, P.L.; Schwartz, M.F.

2005-01-01

Pulsed bed treatment of acid mine drainage (AMD) uses CO2 to accelerate limestone dissolution and intermittent fluidization to abrade and carry away metal hydrolysis products. Tests conducted with a prototype of 60 L/min capacity showed effective removal of H+ acidity over the range 196-584 mg/L (CaCO3) while concurrently generating surplus acid neutralization capacity. Effluent alkalinity (mg/L CaCO3) rose with increases in CO2 (DC, mg/L) according to the model Alkalinity = 31.22 + 2.97(DC)0.5, where DC was varied from 11-726 mg/L. Altering fluidization and contraction periods from 30 s/30 s to 10 s/50 s did not influence alkalinity but did increase energy dissipation and bed expansion ratios. Field trials with three AMD sources demonstrated the process is capable of raising AMD pH above that required for hydrolysis and precipitation of Fe3+ and Al3+ but not Fe2+ and Mn2+. Numerical modeling showed CO2 requirements are reduced as AMD acidity increases and when DC is recycled from system effluent. ?? 2005 Elsevier Ltd. All rights reserved.

Enrichment of rare earth elements as environmental tracers of contamination by acid mine drainage in salt marshes: a new perspective.

PubMed

Delgado, Joaquín; Pérez-López, Rafael; Galván, Laura; Nieto, José Miguel; Boski, Tomasz

2012-09-01

Rare earth elements (REE) were analyzed in surface sediments from the Guadiana Estuary (SW Iberian Pyrite Belt). NASC (North American Shale Composite) normalized REE patterns show clearly convex curvatures in middle-REE (MREE) with respect to light- and heavy-REE, indicating acid-mixing processes between fluvial waters affected by acid mine drainage (AMD) and seawater. However, REE distributions in the mouth (closer to the coastal area) show slightly LREE-enriched and flat patterns, indicating saline-mixing processes typical of the coastal zone. NASC-normalized ratios (La/Gd and La/Yb) do not discriminate between both mixing processes in the estuary. Instead, a new parameter (E(MREE)) has been applied to measure the curvature in the MREE segment. The values of E(MREE)>0 are indicative of acid signatures and their spatial distribution reveal the existence of two decantation zones from flocculation processes related to drought periods and flood events. Studying REE fractionation through the E(MREE) may serve as a good proxy for AMD-pollution in estuarine environments in relation to the traditional methods. Copyright © 2012 Elsevier Ltd. All rights reserved.

Imaging Preferential Flow Pathways of Contaminants from Passive Acid Mine Drainage Mitigation Sites Using Electrical Resistivity

NASA Astrophysics Data System (ADS)

Kelley, N.; Mount, G.; Terry, N.; Herndon, E.; Singer, D. M.

2017-12-01

The Critical Zone represents the surficial and shallow layer of rock, air, water, and soil where most interactions between living organisms and the Earth occur. Acid mine drainage (AMD) resulting from coal extraction can influence both biological and geochemical processes across this zone. Conservative estimates suggest that more than 300 million gallons of AMD are released daily, making this acidic solution of water and contaminants a common issue in areas with legacy or current coal extraction. Electrical resistivity imaging (ERI) provides a rapid and minimally invasive method to identify and monitor contaminant pathways from AMD remediation systems in the subsurface of the Critical Zone. The technique yields spatially continuous data of subsurface resistivity that can be inverted to determine electrical conductivity as a function of depth. Since elevated concentrations of heavy metals can directly influence soil conductivity, ERI data can be used to trace the flow pathways or perhaps unknown mine conduits and transport of heavy metals through the subsurface near acid mine drainage sources. This study aims to examine preferential contaminant migration from those sources through substrate pores, fractures, and shallow mine workings in the near subsurface surrounding AMD sites in eastern Ohio and western Pennsylvania. We utilize time lapse ERI measures during different hydrologic conditions to better understand the variability of preferential flow pathways in relation to changes in stage and discharge within the remediation systems. To confirm ERI findings, and provide constraint to geochemical reactions occurring in the shallow subsurface, we conducted Inductively Coupled Plasma (ICP) spectrometry analysis of groundwater samples from boreholes along the survey transects. Through these combined methods, we can provide insight into the ability of engineered systems to contain and isolate metals in passive acid mine drainage treatment systems.

Geochemical characteristics of Au in the water systemfrom abandoned gold mines area

NASA Astrophysics Data System (ADS)

Cho, Kanghee; Kim, Bongju; Kim, Byungjoo; Park, Cheonyoung; Choi, Nagchoul

2013-04-01

The AMD (acid mine drainage) poses a threat not only to the aquatic life in mountain streams and rivers, but can also contaminate groundwater and downstream water bodies. Besides pyrite, sulfides of copper, zinc, cadmium, lead and arsenic in the drainage tunnels and tailings piles also undergo similar geochemical reactions, releasing toxic metals and more H+ into the mine drainage. The fate of gold in the AMD system is reduced and precipitated with iron oxides by oxidation-reduction reaction between ferrous/ferric iron and Au3+/Au0. The objective of this study was to investigate the influence of the transport characteristic on the distance through distribution of heavy metals and gold on the interrelation between acid mine drainage and sediments in the abandoned Gwang-yang gold mine, Korea. We conducted to confirm the chemical (chemical analysis and sequential extraction) and mineralogical property (XRD, SEM-EDS and polarization microscope) from AMD, sediments and tailing samples. The result of chemical analysis showed that Fe contents in the AMD and sediments from the upstream to the downstream ranged of 10.99 to 18.60 mg/L and 478.74 to 542.98 mg/kg, respectively. Also the contents of Au and As in the sediment were respectively ranged from 14.06 to 22.85 g/t and 0.245 to 0.612 mg/kg. In XRD analysis of the sediments, x-ray diffracted d-value belong to quartz, geothite was observed. The results of SEM-EDS analysis revealed that iron hydroxide were observed in the sediment and tailing. The result of sequential extraction for Au from the sediment showed that Au predominated in 26 to 27% of Organic matter fraction(STEP 4), and 24 to 25% of Residual fraction(STEP 5).

Acid Mine Drainage Research in Gauteng Highlighting Impacts on Infrastructure and Innovation of Concrete-Based Remedial Systems

NASA Astrophysics Data System (ADS)

Diop, S.; Ekolu, S.; Azene, F.

2013-12-01

Acid mine drainage (AMD) is presently one of the most important environmental problems in in the densely populated Gauteng Province, South Africa. The threat of acid mine drainage has demanded short-term interventions (some of which are being implemented by government) but more importantly sustainable long-term innovative solutions. There have been moments of public apprehension with some media reports dubbing the current scenario as a future 'nightmare of biblical proportions' and 'South Africa's own Chernobyl' that could cause dissolving of concrete foundations of buildings and reinforcement steel, leading to collapse of structures. In response to the needs of local and provincial authorities, this research was conducted to (1) generate scientific understanding of the effects of AMD on infrastructure materials and structures, and (2) propose innovative long-term remedial systems based on cementitious materials for potential AMD treatment applications of engineering scale. Two AMD solutions from the goldfields and two others from the coalfields were used to conduct corrosion immersion tests on mild steel, stainless steel, mortars, pastes and concretes. Results show that AMD water from the gold mines is more corrosive than that from the coal mines, the corrosion rate of the former being about twice that of the latter. The functionality of metal components of mild steel can be expected to fail within one month of exposure to the mine water. The investigation has also led to development of a pervious concrete filter system of water-cement ratio = 0.27 and cement content = 360 kg/m3, to be used as a permeable reactive barrier for AMD treatment. Early results show that the system was effective in removing heavy metal contaminants with removal levels of 30% SO4, 99% Fe, 50-83% Mn, 85% Ca, and 30% TDS. Further work is on-going to improve and optimise the system prior to field demonstration studies.

Cytotoxic and genotoxic affects of acid mine drainage on fish Channa punctata (Bloch).

PubMed

Talukdar, B; Kalita, H K; Basumatary, S; Saikia, D J; Sarma, D

2017-10-01

The investigation deals with the effects of Acid Mine Drainage (AMD) of coal mine on fish Channa punctata (Bloch) by examining the incidence of haematological, morphological, histological changes and DNA fragmentation in tissues of C. punctata in laboratory condition. For this study fishes were exposed to 10% of AMD for a period of 30 days. The fusion of the primary and secondary gill lamellae, distortion, loss of alignment, deposition of worn out tissues and mucous on the surface of the lamella in the gills; degeneration of morphological architecture, loss of alignment of tubules, mucous deposition in the kidney; cellular damage, cellular necrosis, extraneous deposition on the surface, pore formation in the liver are some important changes detected by scanning electron microscopy. Fishes of AMD treated group showed gradual significant decrease in TEC, Hb and, increase in TLC and DLC as compared to that of the control. DNA fragmentation observed in kidney of fishes from treated group indicates an intricate pollutant present in the AMD. The high incidence of morphological and histological alterations, haematological changes along with DNA breakage in C. punctata is an evidence of the cytotoxic and genotoxic potential of AMD of coal mines. Copyright © 2017 Elsevier Inc. All rights reserved.

Hydrogeochemical features of surface water and groundwater contaminated with acid mine drainage (AMD) in coal mining areas: a case study in southern Brazil.

PubMed

Galhardi, Juliana Aparecida; Bonotto, Daniel Marcos

2016-09-01

Effects of acid mine drainage (AMD) were investigated in surface waters (Laranjinha River and Ribeirão das Pedras stream) and groundwaters from a coal mining area sampled in two different seasons at Figueira city, Paraná State, Brazil. The spatial data distribution indicated that the acid effluents favor the chemical elements leaching and transport from the tailings pile into the superficial water bodies or aquifers, modifying their quality. The acid groundwaters in both sampling periods (dry: pH 2.94-6.04; rainy: pH 3.25-6.63) were probably due to the AMD generation and infiltration, after the oxidation of sulfide minerals. Such acid effluents cause an increase of the solubilization rate of metals, mainly iron and aluminum, contributing to both groundwater and surface water contamination. Sulfate in high levels is a result of waters' pollution due to AMD. In some cases, high sulfate and low iron contents, associated with less acidic pH values, could indicate that AMD, previously generated, is nowadays being neutralized. The chemistry of the waters affected by AMD is controlled by the pH, sulfide minerals' oxidation, oxygen, iron content, and microbial activity. It is also influenced by seasonal variations that allow the occurrence of dissolution processes and the concentration of some chemical elements. Under the perspective of the waters' quality evaluation, the parameters such as conductivity, dissolved sodium, and sulfate concentrations acted as AMD indicators of groundwaters and surface waters affected by acid effluents.

GROUNDWATER IMPACTED BY ACID MINE DRAINAGE

EPA Science Inventory

The generation and release of acidic, metal-rich water from mine wastes continues to be an intractable environmental problem. Although the effects of acid mine drainage (AMD) are most evident in surface waters, there is an obvious need for developing cost-effective approaches fo...

Interaction of acid mine drainage with Ordinary Portland Cement blended solid residues generated from active treatment of acid mine drainage with coal fly ash.

PubMed

Gitari, Wilson M; Petrik, Leslie F; Key, David L; Okujeni, Charles

2011-01-01

Fly ash (FA) has been investigated as a possible treatment agent for Acid mine drainage (AMD) and established to be an alternative, cheap and economically viable agent compared to the conventional alkaline agents. However, this treatment option also leads to generation of solid residues (SR) that require disposal and one of the proposed disposal method is a backfill in coal mine voids. In this study, the interaction of the SR with AMD that is likely to be present in such backfill scenario was simulated by draining columns packed with SR and SR + 6% Ordinary Portland Cement (OPC) unsaturated with simulated AMD over a 6 month period. The evolving geochemistry of the liquid/solid (L/S) system was evaluated in-terms of the mineral phases likely or controlling contaminants attenuation at the different pH regimes generated. Stepwise acidification of the percolates was observed as the drainage progressed. Two pH buffer zones were observed (7.5-9 and 3-4) for SR and (11.2-11.3 and 3.5-4) for SR + 6% OPC. The solid residue cores (SR) appeared to have a significant buffering capacity, maintaining a neutral to slightly alkaline pH in the leachates for an extended period of time (97 days: L/S 4.3) while SR + 6% OPC reduced this neutralization capacity to 22 days (L/S 1.9). Interaction of AMD with SR or SR + 6% OPC generated alkaline conditions that favored precipitation of Fe, Al, Mn-(oxy) hydroxides, Fe and Ca-Al hydroxysulphates that greatly contributed to the contaminants removal. However, precipitation of these phases was restricted to the pH of the leachates remaining at neutral to circum-neutral levels. Backfill of mine voids with SR promises to be a feasible technology for the disposal of the SR but its success will greatly depend on the disposal scenario, AMD generated and the alkalinity generating potential of the SR. A disadvantage would be the possible re-dissolution of the precipitated phases at pH < 4 that would release the contaminants back to the water column. However extrapolation of this concept to a field scenario can greatly enhance beneficial application of fly ash (FA) and solid residues (SR) generated from treatment of AMD.

Fixed bed sorption of phosphorus from wastewater using iron oxide-based media derived from acid mine drainage

USGS Publications Warehouse

Sibrell, Philip L.; Tucker, T.W.

2012-01-01

Phosphorus (P) releases to the environment have been implicated in the eutrophication of important water bodies worldwide. Current technology for the removal of P from wastewaters consists of treatment with aluminum (Al) or iron (Fe) salts, but is expensive. The neutralization of acid mine drainage (AMD) generates sludge rich in Fe and Al oxides that has hitherto been considered a waste product, but these sludges could serve as an economical adsorption media for the removal of P from wastewaters. Therefore, we have evaluated an AMD-derived media as a sorbent for P in fixed bed sorption systems. The homogenous surface diffusion model (HSDM) was used to analyze fixed bed test data and to determine the value of related sorption parameters. The surface diffusion modulus Ed was found to be a useful predictor of sorption kinetics. Values of Ed < 0.2 were associated with early breakthrough of P, while more desirable S-shaped breakthrough curves resulted when 0.2 < Ed < 0.5. Computer simulations of the fixed bed process with the HSDM confirmed that if Ed was known, the shape of the breakthrough curve could be calculated. The surface diffusion coefficient D s was a critical factor in the calculation of Ed and could be estimated based on the sorption test conditions such as media characteristics, and influent flow rate and concentration. Optimal test results were obtained with a relatively small media particle size (average particle radius 0.028 cm) and resulted in 96 % removal of P from the influent over 46 days of continuous operation. These results indicate that fixed bed sorption of P would be a feasible option for the utilization of AMD residues, thus helping to decrease AMD treatment costs while at the same time ameliorating the impacts of P contamination.

Significant seasonal variations of microbial community in an acid mine drainage lake in Anhui Province, China.

PubMed

Hao, Chunbo; Wei, Pengfei; Pei, Lixin; Du, Zerui; Zhang, Yi; Lu, Yanchun; Dong, Hailiang

2017-04-01

Acid mine drainage (AMD),characterized by strong acidity and high metal concentrations, generates from the oxidative dissolution of metal sulfides, and acidophiles can accelerate the process significantly. Despite extensive research in microbial diversity and community composition, little is known about seasonal variations of microbial community structure (especially micro eukaryotes) in response to environmental conditions in AMD ecosystem. To this end, AMD samples were collected from Nanshan AMD lake, Anhui Province, China, over a full seasonal cycle from 2013 to 2014, and water chemistry and microbial composition were studied. pH of lake water was stable (∼3.0) across the sampling period, while the concentrations of ions varied dramatically. The highest metal concentrations in the lake were found for Mg and Al, not commonly found Fe. Unexpectedly, ultrahigh concentration of chlorophyll a was measured in the extremely acidic lake, reaching 226.43-280.95 μg/L in winter, even higher than those in most eutrophic freshwater lakes. Both prokaryotic and eukaryotic communities showed a strong seasonal variation. Among the prokaryotes, "Ferrovum", a chemolithotrophic iron-oxidizing bacterium was predominant in most sampling seasons, although it was a minor member prior to September, 2012. Fe 2+ was the initial geochemical factor that drove the variation of the prokaryotic community. The eukaryotic community was simple but varied more drastically than the prokaryotic community. Photoautotrophic algae (primary producers) formed a food web with protozoa or flagellate (top consumers) across all four seasons, and temperature appeared to be responsible for the observed seasonal variation. Ochromonas and Chlamydomonas (responsible for high algal bloom in winter) occurred in autumn/summer and winter/spring seasons, respectively, because of their distinct growth temperatures. The closest phylogenetic relationship between Chlamydomonas species in the lake and those in Arctic and Alpine suggested that the native Chlamydomonas species may have been both acidophilic and psychrophilic after a long acclimation time in this extreme environment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Characterization of the microbial community composition and the distribution of Fe-metabolizing bacteria in a creek contaminated by acid mine drainage.

PubMed

Sun, Weimin; Xiao, Enzong; Krumins, Valdis; Dong, Yiran; Xiao, Tangfu; Ning, Zengping; Chen, Haiyan; Xiao, Qingxiang

2016-10-01

A small watershed heavily contaminated by long-term acid mine drainage (AMD) from an upstream abandoned coal mine was selected to study the microbial community developed in such extreme system. The watershed consists of AMD-contaminated creek, adjacent contaminated soils, and a small cascade aeration unit constructed downstream, which provide an excellent contaminated site to study the microbial response in diverse extreme AMD-polluted environments. The results showed that the innate microbial communities were dominated by acidophilic bacteria, especially acidophilic Fe-metabolizing bacteria, suggesting that Fe and pH are the primary environmental factors in governing the indigenous microbial communities. The distribution of Fe-metabolizing bacteria showed distinct site-specific patterns. A pronounced shift from diverse communities in the upstream to Proteobacteria-dominated communities in the downstream was observed in the ecosystem. This location-specific trend was more apparent at genus level. In the upstream samples (sampling sites just below the coal mining adit), a number of Fe(II)-oxidizing bacteria such as Alicyclobacillus spp., Metallibacterium spp., and Acidithrix spp. were dominant, while Halomonas spp. were the major Fe(II)-oxidizing bacteria observed in downstream samples. Additionally, Acidiphilium, an Fe(III)-reducing bacterium, was enriched in the upstream samples, while Shewanella spp. were the dominant Fe(III)-reducing bacteria in downstream samples. Further investigation using linear discriminant analysis (LDA) effect size (LEfSe), principal coordinate analysis (PCoA), and unweighted pair group method with arithmetic mean (UPGMA) clustering confirmed the difference of microbial communities between upstream and downstream samples. Canonical correspondence analysis (CCA) and Spearman's rank correlation indicate that total organic carbon (TOC) content is the primary environmental parameter in structuring the indigenous microbial communities, suggesting that the microbial communities are shaped by three major environmental parameters (i.e., Fe, pH, and TOC). These findings were beneficial to a better understanding of natural attenuation of AMD.

Evidence for the Stepwise Stress Model: Gambusia holbrooki and Daphnia magna under acid mine drainage and acidified reference water stress.

PubMed

Gerhardt, Almut; Janssens de Bisthoven, Luc; Soares, Amadeu M V

2005-06-01

The Stepwise Stress Model (SSM) states that a cascade of regulative behavioral responses with different intrinsic sensitivities and threshold values offers increased behavioral plasticity and thus a wider range of tolerance for environmental changes or pollutant exposures. We tested the SSM with a widely introduced fish Gambusia holbrooki (Girard) (Pisces, Poeciliidae) and the standard laboratory test species Daphnia magna Straus (Crustacea, Daphniidae). The stress was simulated by short-term exposure to acid mine drainage (AMD) and to acidified reference water (ACID). Recording of behavioral responses with the multispecies freshwater biomonitor (MFB) generated continuous time-dependent dose-response data that were modeled in three-dimensional (3D) surface plots. Both the pH-dependent mortalities and the strong linear correlations between pH and aqueous metals confirmed the toxicity of the AMD and ACID gradients, respectively, for fish and Daphnia, the latter being more sensitive. AMD stress at pH < or = 5.5 amplified circadian rhythmicity in both species, while ACID stress did so only in G. holbrooki. A behavioral stepwise stress response was found in both species: D. magna decreased locomotion and ventilation (first step) (AMD, ACID), followed by increased ventilation (second step) (AMD). G. holbrooki decreased locomotion (first step) (AMD, ACID) and increased ventilation at intermediate pH levels (second step) (AMD). Both species, although from different taxonomic groups and feeding habits, followed the SSM, which might be expanded to a general concept for describing the behavioral responses of aquatic organims to pollution. Stepwise stress responses might be applied in online biomonitors to provide more sensitive and graduated alarm settings, hence optimizing the "early warning" detection of pollution waves.

Efficacy assessment of acid mine drainage treatment with coal mining waste using Allium cepa L. as a bioindicator.

PubMed

Geremias, Reginaldo; Bortolotto, Tiago; Wilhelm-Filho, Danilo; Pedrosa, Rozangela Curi; de Fávere, Valfredo Tadeu

2012-05-01

The aim of this study was to evaluate the efficacy of the treatment of acid mine drainage (AMD) with calcinated coal mining waste using Allium cepa L. as a bioindicator. The pH values and the concentrations of aluminum, iron, manganese, zinc, copper, lead and sulfate were determined before and after the treatment of the AMD with calcinated coal mining waste. Allium cepa L. was exposed to untreated and treated AMD, as well as to mineral water as a negative control (NC). At the end of the exposure period, the inhibition of root growth was measured and the mean effective concentration (EC(50)) was determined. Oxidative stress biomarkers such as lipid peroxidation (TBARS), protein carbonyls (PC), catalase activity (CAT) and reduced glutathione levels (GSH) in the fleshy leaves of the bulb, as well as the DNA damage index (ID) in meristematic cells, were evaluated. The results indicated that the AMD treatment with calcinated coal mining waste resulted in an increase in the pH and an expressive removal of aluminum, iron, manganese and zinc. A high sub-chronic toxicity was observed when Allium cepa L. was exposed to the untreated AMD. However, after the treatment no toxicity was detected. Levels of TBARS and PC, CAT activity and the DNA damage index were significantly increased (P<0.05) in Allium cepa L. exposed to untreated AMD when compared to treated AMD and also to negative controls. No significant alteration in the GSH content was observed. In conclusion, the use of calcinated coal mining waste associated with toxicological tests on Allium cepa L. represents an alternative system for the treatment and biomonitoring of these types of environmental contaminants. Copyright © 2011 Elsevier Inc. All rights reserved.

Radium and barium removal through blending hydraulic fracturing fluids with acid mine drainage.

PubMed

Kondash, Andrew J; Warner, Nathaniel R; Lahav, Ori; Vengosh, Avner

2014-01-21

Wastewaters generated during hydraulic fracturing of the Marcellus Shale typically contain high concentrations of salts, naturally occurring radioactive material (NORM), and metals, such as barium, that pose environmental and public health risks upon inadequate treatment and disposal. In addition, fresh water scarcity in dry regions or during periods of drought could limit shale gas development. This paper explores the possibility of using alternative water sources and their impact on NORM levels through blending acid mine drainage (AMD) effluent with recycled hydraulic fracturing flowback fluids (HFFFs). We conducted a series of laboratory experiments in which the chemistry and NORM of different mix proportions of AMD and HFFF were examined after reacting for 48 h. The experimental data combined with geochemical modeling and X-ray diffraction analysis suggest that several ions, including sulfate, iron, barium, strontium, and a large portion of radium (60-100%), precipitated into newly formed solids composed mainly of Sr barite within the first ∼ 10 h of mixing. The results imply that blending AMD and HFFF could be an effective management practice for both remediation of the high NORM in the Marcellus HFFF wastewater and beneficial utilization of AMD that is currently contaminating waterways in northeastern U.S.A.

Generation of acid mine drainage around the Karaerik copper mine (Espiye, Giresun, NE Turkey): implications from the bacterial population in the Acısu effluent.

PubMed

Sağlam, Emine Selva; Akçay, Miğraç; Çolak, Dilşat Nigar; İnan Bektaş, Kadriye; Beldüz, Ali Osman

2016-09-01

The Karaerik Cu mine is a worked-out deposit with large volumes of tailings and slags which were left around the mine site without any protection. Natural feeding of these material and run-off water from the mineralised zones into the Acısu effluent causes a serious environmental degradation and creation of acid mine drainage (AMD) along its entire length. This research aims at modelling the formation of AMD with a specific attempt on the characterisation of the bacterial population in association with AMD and their role on its occurrence. Based on 16SrRNA analyses of the clones obtained from a composite water sample, the bacterial community was determined to consist of Acidithiobacillus ferrivorans, Ferrovum myxofaciens, Leptospirillum ferrooxidans and Acidithiobacillus ferrooxidans as iron-oxidising bacteria, Acidocella facilis, Acidocella aluminiidurans, Acidiphilium cryptum and Acidiphilium multivorum as iron-reducing bacteria, and Acidithiobacillus ferrivorans, Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Acidiphilium cryptum as sulphur-oxidising bacteria. This association of bacteria with varying roles was interpreted as evidence of a concomitant occurrence of sulphur and iron cycles during the generation of AMD along the Acısu effluent draining the Karaerik mine.

LABORATORY EVALUATION OF ZERO-VALENT IRON TO TREAT GROUNDWATER IMPACTED BY ACID MINE DRAINAGE

EPA Science Inventory

The generation and release of acidic, metal-rich water from mine wastes continues to be an intractable environmental problem. Although the effects of acid mine drainage (AMD) are most evident in surface waters, there is an obvious need for developing cost-effective approaches fo...

VALUING ACID MINE DRAINAGE REMEDIATION IN WEST VIRGINIA: BENEFIT TRANSFER WITH PREFERENCE CALIBRATION

EPA Science Inventory

Several thousand kilometers of West Virginia streams are degraded by acid mine drainage (AMD), and the estimates for cleanup range in the billions of dollars. Not enough money is available to restore all the affected streams, so some way to prioritize those streams is needed. Ben...

Combined DC resistivity and induced polarization (DC-IP) for mapping the internal composition of a mine waste rock pile in Nova Scotia, Canada

NASA Astrophysics Data System (ADS)

Power, Christopher; Tsourlos, Panagiotis; Ramasamy, Murugan; Nivorlis, Aristeidis; Mkandawire, Martin

2018-03-01

Mine waste rock piles (WRPs) can contain sulfidic minerals whose interaction with oxygen and water can generate acid mine drainage (AMD). Thus, WRPs can be a long-term source of environmental pollution. Since the generation of AMD and its release into the environment is dependent on the net volume and bulk composition of waste rock, effective characterization of WRPs is necessary for successful remedial design and monitoring. In this study, a combined DC resistivity and induced polarization (DC-IP) approach was employed to characterize an AMD-generating WRP in the Sydney Coalfield, Nova Scotia, Canada. Two-dimensional (2D) DC-IP imaging with 6 survey lines was performed to capture the full WRP landform. 2D DC results indicated a highly heterogeneous and moderately conductive waste rock underlain by a resistive bedrock containing numerous fractures. 2D IP (chargeability) results identified several highly-chargeable regions within the waste, with normalized chargeability delineating regions specific to waste mineralogy only. Three-dimensional (3D) DC-IP imaging, using 17 parallel lines on the plateau of the pile, was then used to focus on the composition of the waste rock. The full 3D inverted DC-IP distributions were used to identify coincident and continuous zones (isosurfaces) of low resistivity (<30 Ω-m) and high normalized chargeability (>0.4 mS/m) that were inferred as generated AMD (leachate) and stored AMD (sulfides), respectively. Integrated geological, hydrogeological and geochemical data increased confidence in the geoelectrical interpretations. Knowledge on the location of potentially more reactive waste material is extremely valuable for improved long-term AMD monitoring at the WRP.

Co-treatment of abandoned mine drainage and Marcellus Shale flowback water for use in hydraulic fracturing.

PubMed

He, Can; Zhang, Tieyuan; Vidic, Radisav D

2016-11-01

Flowback water generated during shale gas extraction in Pennsylvania is mostly reused for hydraulic fracturing operation. Abandoned mine drainage (AMD), one of the most widespread threats to water quality in Pennsylvania, can potentially serve as a make-up water source to enable flowback water reuse. This study demonstrated co-treatment of flowback water and AMD produced in northeastern Pennsylvania in a pilot-scale system consisting of rapid mix reactor, flocculation tank and sedimentation tank. Sulfate concentration in the finished water can be controlled at a desired level (i.e., below 100 mg/L) by adjusting the ratio of flowback water and AMD in the influent. Fe 3+ contained in the AMD can serve as a coagulant to enhance the removal of suspended solids, during which Fe 2+ is co-precipitated and the total iron is reduced to a desirable level. Solid waste generated in this process (i.e., barite) will incorporate over 99% of radium present in the flowback water, which offers the possibility to control the fate of naturally occurring radioactive materials (NORM) brought to the surface by unconventional gas extraction. Sludge recirculation in the treatment process can be used to increase the size of barite particles formed by mixing flowback water and AMD to meet specifications for use as a weighting agent in drilling fluid. This alternative management approach for NORM can be used to offset the treatment cost and promote flowback water reuse, reduce environmental impacts of AMD and reduce pressure on fresh water sources. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Positive Environmental Contribution of Jarosite by Retaining Lead in Acid Mine Drainage Areas

PubMed Central

Figueiredo, Maria-Ondina; da Silva, Teresa Pereira

2011-01-01

Jarosite, KFe3(SO4)2(OH)6, is a secondary iron sulphate often found in acid mine drainage (AMD) environments, particularly in mining wastes from polymetallic sulphide ore deposits. Despite the negative environmental connotation usually ascribed to secondary sulphate minerals due to the release of hazardous elements to aquifers and soils, jarosite acts as an efficient remover and immobilizer of such metals, particularly lead. The mineral chemistry of jarosite is reviewed and the results of a Fe K-edge XANES (X-Ray Absorption Near-Edge Structure) study of K-, Na- and Pb-jarosite are described and discussed within the context of the abandoned old mines of São Domingos and Aljustrel located in southern Portugal, in the Iberian Pyrite Belt (IPB). PMID:21655138

A Novel Treatment for Acid Mine Drainage Utilizing Reclaimed Limestone Residual

DOE Office of Scientific and Technical Information (OSTI.GOV)

Horace K. Moo-Young; Charles E. Ochola

2004-08-31

The viability of utilizing Reclaimed Limestone Residual (RLR) to remediate Acid Mine Drainage (AMD) was investigated. Physical and chemical characterization of RLR showed that it is composed of various minerals that contain significant quantities of limestone or calcium bearing compounds that can be exploited for acid neutralization. Acid Neutralization Potential (ANP) test results showed that RLR has a neutralization potential of approximately 83% as calcium carbonate (CaCO{sub 3}). Neutralization tests with most of the heavy metals associated with AMD showed removal efficiencies of over 99%. An unexpected benefit of utilizing RLR was the removal of hexavalent chromium Cr (VI) frommore » the aqueous phase. Due to an elevation in pH by RLR most AMD heavy metals are removed from solution by precipitation as their metal hydroxides. Cr (VI) however is not removed by pH elevation and therefore subsequent ongoing tests to elucidate the mechanism responsible for this reaction were conducted.« less

Corrosion control when using passively treated abandoned mine drainage as alternative makeup water for cooling systems.

PubMed

Hsieh, Ming-Kai; Chien, Shih-Hsiang; Li, Heng; Monnell, Jason D; Dzombak, David A; Vidic, Radisav D

2011-09-01

Passively treated abandoned mine drainage (AMD) is a promising alternative to fresh water as power plant cooling water system makeup water in mining regions where such water is abundant. Passive treatment and reuse of AMD can avoid the contamination of surface water caused by discharge of abandoned mine water, which typically is acidic and contains high concentrations of metals, especially iron. The purpose of this study was to evaluate the feasibility of reusing passively treated AMD in cooling systems with respect to corrosion control through laboratory experiments and pilot-scale field testing. The results showed that, with the addition of the inhibitor mixture orthophosphate and tolyltriazole, mild steel and copper corrosion rates were reduced to acceptable levels (< 0.127 mm/y and < 0.0076 mm/y, respectively). Aluminum had pitting corrosion problems in every condition tested, while cupronickel showed that, even in the absence of any inhibitor and in the presence of the biocide monochloramine, its corrosion rate was still very low (0.018 mm/y).

Environmental assessment and management of metal-rich wastes generated in acid mine drainage passive remediation systems.

PubMed

Macías, Francisco; Caraballo, Manuel A; Nieto, José Miguel

2012-08-30

As acid mine drainage (AMD) remediation is increasingly faced by governments and mining industries worldwide, the generation of metal-rich solid residues from the treatments plants is concomitantly raising. A proper environmental management of these metal-rich wastes requires a detailed characterization of the metal mobility as well as an assessment of this new residues stability. The European standard leaching test EN 12457-2, the US EPA TCLP test and the BCR sequential extraction procedure were selected to address the environmental assessment of dispersed alkaline substrate (DAS) residues generated in AMD passive treatment systems. Significant discrepancies were observed in the hazardousness classification of the residues according to the TCLP or EN 12457-2 test. Furthermore, the absence of some important metals (like Fe or Al) in the regulatory limits employed in both leaching tests severely restricts their applicability for metal-rich wastes. The results obtained in the BCR sequential extraction suggest an important influence of the landfill environmental conditions on the metals released from the wastes. To ensure a complete stability of the pollutants in the studied DAS-wastes the contact with water or any other leaching solutions must be avoided and a dry environment needs to be provided in the landfill disposal selected. Copyright © 2012 Elsevier B.V. All rights reserved.

Preliminary Results: Release Of Metals From Acid-Mine Drainage Contaminated Streambed Sediments Under Anaerobic Conditions (Presentation)

EPA Science Inventory

Many miles of streams in the western U.S. are contaminated with acid-mine drainage (AMD) from abandoned metal mines. Treatment of these streams may include removal of the existing sediments, with subsequent burial (e.g., in a repository). Burial of previously aerobic sediments ma...

PRELIMINARY RESULTS: RELEASE OF METALS FROM ACID-MINE DRAINAGE CONTAMINATED STREAMBED SEDIMENTS UNDER ANOXIC CONDITIONS

EPA Science Inventory

Many miles of streams are contaminated with acid-mine drainage (AMD) from abandoned metal mines in the western U.S. Treatment of these streams may include dredging of the existing sediments, with subsequent burial. Burial of previously toxic sediments may result in release of met...

Preliminary Results: Release Of Metals From Acid-Mine Drainage Contaminated Streambed Sediments Under Anaerobic Conditions

EPA Science Inventory

Many miles of streams in the western U.S. are contaminated with acid-mine drainage (AMD) from abandoned metal mines. Treatment of these streams may include removal of the existing sediments, with subsequent burial (e.g., in a repository). Burial of previously aerobic sediments ma...

Roles of Benthic Algae in the Structure, Function, and Assessment of Stream Ecosystems Affected by Acid Mine Drainage

EPA Science Inventory

Tens of thousands of stream kilometers around the world are degraded by a legacy of environmental impacts and acid mine drainage (AMD) caused by abandoned underground and surface mines, piles of discarded coal wastes, and tailings. Increased acidity, high concentrations of metals...

Application of mine water leaching protocol on coal fly ash to assess leaching characteristics for suitability as a mine backfill material.

PubMed

Madzivire, Godfrey; Ramasenya, Koena; Tlowana, Supi; Coetzee, Henk; Vadapalli, Viswanath R K

2018-04-16

Over the years, coal mining in the Mpumalanga Province of South Africa has negatively affected the environment by causing pollution of water resources, land subsidence and spontaneous coal combustion. Previous studies show that in-situ treatment of acid mine drainage (AMD) using coal fly ash (CFA) from local power stations was possible and sludge recovered out of such treatment can be used to backfill mines. In this article, the authors have attempted to understand the leaching characteristics of CFA when placed underground as a backfill material using the mine water leaching protocol (MWLP). The results show that the migration of contaminants between the coal fly ash and the AMD in the mine voids depends on the pH and quality of the mine water. While backfilling mine voids with CFA can neutralize and scavenge between 50% and 95% of certain environmentally sensitive elements from AMD such as Fe, Al, Zn, Cu, Ni, Co and Mn. At this moment, it is also important to point out that certain scavenged/removed contaminants from the AMD during initial phases of backfilling can be remobilized by the influx of acidic water into the mine voids. It has therefore been concluded that, while CFA can be used to backfill mine voids, the influx of fresh acidic mine water should be avoided to minimize the remobilization of trapped contaminants such as Fe, Al, Mn and As. However, the pozzolanic material resulting from the CFA-AMD interaction could prevent such influx.

Denitrification potential in stream sediments impacted by acid mine drainage: Effects of pH, various electron donors, and iron

USGS Publications Warehouse

Baeseman, J.L.; Smith, R.L.; Silverstein, J.

2006-01-01

Acid mine drainage (AMD) contaminates thousands of kilometers of stream in the western United States. At the same time, nitrogen loading to many mountain watersheds is increasing because of atmospheric deposition of nitrate and increased human use. Relatively little is known about nitrogen cycling in acidic, heavy-metal-laden streams; however, it has been reported that one key process, denitrification, is inhibited under low pH conditions. The objective of this research was to investigate the capacity for denitrification in acidified streams. Denitrification potential was assessed in sediments from several Colorado AMD-impacted streams, ranging from pH 2.60 to 4.54, using microcosm incubations with fresh sediment. Added nitrate was immediately reduced to nitrogen gas without a lag period, indicating that denitrification enzymes were expressed and functional in these systems. First-order denitrification potential rate constants varied from 0.046 to 2.964 day-1. The pH of the microcosm water increased between 0.23 and 1.49 pH units during denitrification. Additional microcosm studies were conducted to examine the effects of initial pH, various electron donors, and iron (added as ferrous and ferric iron). Decreasing initial pH decreased denitrification; however, increasing pH had little effect on denitrification rates. The addition of ferric and ferrous iron decreased observed denitrification potential rate constants. The addition of glucose and natural organic matter stimulated denitrification potential. The addition of hydrogen had little effect, however, and denitrification activity in the microcosms decreased after acetate addition. These results suggest that denitrification can occur in AMD streams, and if stimulated within the environment, denitrification might reduce acidity. ?? Springer Science+Business Media, Inc. 2006.

Efficient recovery of nano-sized iron oxide particles from synthetic acid-mine drainage (AMD) water using fuel cell technologies.

PubMed

Cheng, Shaoan; Jang, Je-Hun; Dempsey, Brian A; Logan, Bruce E

2011-01-01

Acid mine drainage (AMD) is an important contributor to surface water pollution due to the release of acid and metals. Fe(II) in AMD reacts with dissolved oxygen to produce iron oxide precipitates, resulting in further acidification, discoloration of stream beds, and sludge deposits in receiving waters. It has recently been shown that new fuel cell technologies, based on microbial fuel cells, can be used to treat AMD and generate electricity. Here we show that this approach can also be used as a technique to generate spherical nano-particles of iron oxide that, upon drying, are transformed to goethite (α-FeOOH). This approach therefore provides a relatively straightforward way to generate a product that has commercial value. Particle diameters ranged from 120 to 700 nm, with sizes that could be controlled by varying the conditions in the fuel cell, especially current density (0.04-0.12 mA/cm(2)), pH (4-7.5), and initial Fe(II) concentration (50-1000 mg/L). The most efficient production of goethite and power occurred with pH = 6.3 and Fe(II) concentrations above 200 mg/L. These results show that fuel cell technologies can not only be used for simultaneous AMD treatment and power generation, but that they can generate useful products such as iron oxide particles having sizes appropriate for used as pigments and other applications. Copyright © 2010 Elsevier Ltd. All rights reserved.

Investigating the formation of acid mine drainage of Toledo pyrite concentrate using column cells

NASA Astrophysics Data System (ADS)

Aguila, Diosa Marie

2018-01-01

Acid mine drainage (AMD) is an inevitable problem in mining and has adverse effects in water quality. Studying AMD formation will be valuable in controlling the composition of mine waters and in planning the rehabilitation method for a mine. In this research, kinetics of AMD formation of Toledo pyrite was studied using two column experiments. The mechanisms of AMD formation and the effects of various factors on pH drop were first studied. Another column test was done for validation and to study the role of Fe2+/Fe3+ ratio in the change of leachate pH. The first experiment revealed that time and particle size are the most significant factors. It was also observed that the sudden pH drop during the starting hours was due to cracks formed from beneficiation, and the formation of Fe(OH)3. The laddered behavior of pH thereafter was due to decrease in formation of Fe(OH)3, and the precipitates in pyrite surface that lowered the surface area available for pyrite oxidation. The results of the second experiment validated the laddered behavior of pH. It was also observed that particle size distribution and pyrite surface were affected by the change in pH. Fe2+/Fe3+ ratio of leachate generally decreased as pH dropped.

Selection of Clostridium spp. in biological sand filters neutralizing synthetic acid mine drainage.

PubMed

Ramond, Jean-Baptiste; Welz, Pamela J; Le Roes-Hill, Marilize; Tuffin, Marla I; Burton, Stephanie G; Cowan, Don A

2014-03-01

In this study, three biological sand filter (BSF) were contaminated with a synthetic iron- [1500 mg L⁻¹ Fe(II), 500 mg L⁻¹ Fe(III)] and sulphate-rich (6000 mg L⁻¹ SO₄²⁻) acid mine drainage (AMD) (pH = 2), for 24 days, to assess the remediation capacity and the evolution of autochthonous bacterial communities (monitored by T-RFLP and 16S rRNA gene clone libraries). To stimulate BSF bioremediation involving sulphate-reducing bacteria, a readily degradable carbon source (glucose, 8000 mg L⁻¹) was incorporated into the influent AMD. Complete neutralization and average removal efficiencies of 81.5 (±5.6)%, 95.8 (±1.2)% and 32.8 (±14.0)% for Fe(II), Fe(III) and sulphate were observed, respectively. Our results suggest that microbial iron reduction and sulphate reduction associated with iron precipitation were the main processes contributing to AMD neutralization. The effect of AMD on BSF sediment bacterial communities was highly reproducible. There was a decrease in diversity, and notably a single dominant operational taxonomic unit (OTU), closely related to Clostridium beijerinckii, which represented up to 65% of the total community at the end of the study period. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Mine Water Treatment in Hongai Coal Mines

NASA Astrophysics Data System (ADS)

Dang, Phuong Thao; Dang, Vu Chi

2018-03-01

Acid mine drainage (AMD) is recognized as one of the most serious environmental problem associated with mining industry. Acid water, also known as acid mine drainage forms when iron sulfide minerals found in the rock of coal seams are exposed to oxidizing conditions in coal mining. Until 2009, mine drainage in Hongai coal mines was not treated, leading to harmful effects on humans, animals and aquatic ecosystem. This report has examined acid mine drainage problem and techniques for acid mine drainage treatment in Hongai coal mines. In addition, selection and criteria for the design of the treatment systems have been presented.

Assessment, water-quality trends, and options for remediation of acidic drainage from abandoned coal mines near Huntsville, Missouri, 2003-2004

USGS Publications Warehouse

Christensen, Eric D.

2005-01-01

Water from abandoned underground coal mines acidifies receiving streams in the Sugar Creek Basin and Mitchell Mine Basin near Huntsville, Missouri. A 4.35-kilometer (2.7-mile) reach of Sugar Creek has been classified as impaired based on Missouri's Water Quality Standards because of small pH values [< (less than) 6.5]. Samples collected from Sugar Creek from July 2003 to June 2004 did not have pH values outside of the specified range of 6.5 to 9.0. However, large concentrations of iron [416 to 2,320 mg/L (milligrams per liter)], manganese (8.36 to 33.5 mg/L), aluminum (0.870 to 428 mg/L), and sulfate (2,990 to 13,700 mg/L) in acidic mine drainage (AMD) from two mine springs as well as small and diffuse seeps were observed to have an effect on water quality in Sugar Creek. Metal and sulfate loads increased and pH decreased immediately downstream from Sugar Creek's confluence with the Calfee Slope and Huntsville Gob drainages that discharge AMD into Sugar Creek. Similar effects were observed in the Mitchell Mine drainage that receives AMD from a large mine spring. Comparisons of water-quality samples from this study and two previous studies by the U.S. Geological Survey in 1987-1988 and the Missouri Department of Natural Resources in 2000-2002 indicate that AMD generation in the Sugar Creek Basin and Mitchell Mine Basin is declining, but the data are insufficient to quantify any trends or time frame. AMD samples from the largest mine spring in the Calfee Slope subbasin indicated a modest but significant increase in median pH from 4.8 to 5.2 using the Wilcoxan rank-sum test (p <0.05) and a decrease in median specific conductance from 5,000 to 3,540 ?S/cm (microsiemens per centimeter at 25 degrees Celsius) during a 17-year period. AMD samples from the largest mine spring in the Mitchell Mine Basin indicated an increase in median pH values from 5.6 to 6.0 and a decrease in median specific conductance from 3,050 to 2,450 ?S/cm during the same period. Remediation of AMD at or near the sites of the three largest mine springs is geochemically feasible based on alkalinity addition rates and increased pH determined by cubitainer experiments and geochemical mixing experiments using the computer model PHREEQCI. Alkalinity values for seven cubitainer experiments conducted to simulate anoxic treatment options exceeded the targeted value for alkalinity [90 mg/L as calcium carbonate (CaCO3)] specified in Missouri's Total Maximum Daily Load program by 18 percent or more, but maximum pH values were between 6.2 and 6.3, which is less than the targeted pH value of 6.5. Treatment of AMD by mixing with stream water or sewage effluent can further increase pH as indicated by geochemical modeling, but will not totally achieve water-quality goals because of limited discharges. A combination of treatments including settling ponds, oxic or anoxic limestone drains, and possibly successive alkalinity producing systems to remediate AMD will likely be required in the Sugar Creek Basin and Mitchell Mine Basin to consistently meet Missouri's Water Quality Standards.

Geochemical processes controlling fate and transport of arsenic in acid mine drainage (AMD) and natural systems.

PubMed

Cheng, Hefa; Hu, Yuanan; Luo, Jian; Xu, Bin; Zhao, Jianfu

2009-06-15

Acid mine drainage (AMD) is often accompanied with elevated concentrations of arsenic, in the forms of arsenite, As(III), and/or arsenate, As(V), due to the high affinity of arsenic for sulfide mineral ores. This review summarizes the major geochemical processes controlling the release, speciation, fate, and distribution of inorganic arsenic in mine drainage and natural systems. Arsenic speciation depends highly on redox potential and pH of the solution, and arsenite can be oxidized to the less toxic arsenate form. Homogeneous oxidation of arsenite occurs rather slowly while its heterogeneous oxidation on mineral surfaces can greatly enhance the reaction rates. Little evidence suggests that precipitation reaction limits the concentrations of arsenic in natural water, while co-precipitation may lead to rapid arsenic removal when large amount of iron hydroxides precipitate out of the aqueous phase upon neutralization of the mine drainage. Both arsenate and arsenite adsorb on common metal oxides and clay minerals through formation of inner-sphere and/or outer-sphere complexes, controlling arsenic concentration in natural water bodies. Arsenite adsorbs less strongly than arsenate in the typical pH range of natural water and is more mobile. Part of the adsorbed arsenic species can be exchanged by common anions (e.g., PO(4)(3-) and SO(4)(2-)), especially phosphate, which leads to their re-mobilization. Understanding the geochemistry of arsenic is helpful for predicting its mobility and fate in AMD and natural systems, and for designing of cost-effective remediation/treatment strategies to reduce the occurrence and risk of arsenic contamination.

Simulation of acid mine drainage generation around Küre VMS Deposits, Northern Turkey

NASA Astrophysics Data System (ADS)

Demirel, Cansu; Kurt, Mehmet Ali; Çelik Balci, Nurgül

2015-04-01

This study investigated comparative leaching characteristics of acidophilic bacterial strains under shifting environmental conditions at proposed two stages as formation stage or post acidic mine drainage (AMD) generation. At the first stage, initial reactions associated with AMD generation was simulated in shaking flasks containing massive pyritic chalcopyrite ore by using a pure strain Acidithiobacillus ferrooxidans and a mixed culture of Acidithiobacillus sp. mostly dominated by A. ferrooxidans and A. thiooxidans at 26oC. At the second stage, long term bioleaching experiments were carried out with the same strains at 26oC and 40oC to investigate the leaching characteristics of pyritic chalcopyrite ore under elevated heavy metal and temperature conditions. During the experiments, physicochemical characteristics (e.i. Eh, pH, EC) metal (Fe, Co, Cu, Zn) and sulfate concentration of the experimental solution were monitored during 180 days. Significant acid generation and sulfate release were determined during bioleaching of the ore by mixed acidophilic cultures containing both iron and sulfur oxidizers. In the early stage of the experiments, heavy metal release from the ore was caused by generation of acid due to accelerated bacterial oxidation of the ore. Generally high concentrations of Co and Cu were released into the solution from the experiments conducted by pure cultures of Acidithiobacillus ferrooxidans whereas high Zn and Fe was released into the solution from the mixed culture experiments. In the later stage of AMD generation and post AMD, chemical oxidation is accelerated causing excessive amounts of contamination, even exceeding the amounts resulted from bacterial oxidation by mixed cultures. Acidithibacillus ferrooxidans was found to be more effective in leaching Cu, Fe and Co at higher temperatures in contrary to mixed acidophiles that are more prone to operate at optimal moderate conditions. Moreover, decreasing Fe values are noted in bioleaching experiments with mixed acidophiles at higher temperatures. Further depleted Fe(III) values coinciding with decreasing pH may point to precipitation of secondary phases (i.e. jarosite). This study revealed that the metals (Fe, Cu, Co and Zn) released during short term leaching of the ore (34 days) are generally caused by acid produced by dissolution reactions rather than oxidation. In the long term experiments a more complex biogeochemical reactions (oxidation and dissolution) take place in conjunction. Key words: Bioleaching, AMD, heavy metal release, environment, acidophilic bacteria, Küre copper ore deposits, volcanogenic massive sulfide deposits

Assessment of characteristics and remedial alternatives for abandoned mine drainage : case study at Staple Bend Tunnel unit of Allegheny Portage Railroad National Historic Site, Cambria County, Pennsylvania, 2004

USGS Publications Warehouse

Cravotta, Charles A.

2005-01-01

This report describes field, laboratory, and computational methods that could be used to assess remedial strategies for abandoned mine drainage (AMD). During April-June, 2004, the assessment process was applied to AMD from bituminous coal deposits at a test site in the Staple Bend Tunnel Unit of Allegheny Portage Railroad National Historic Site (ALPO-SBTU) in Cambria County, Pennsylvania. The purpose of this study was (1) to characterize the AMD quantity and quality within the ALPO-SBTU test site; (2) to evaluate the efficacy of limestone or steel slag for neutralization of the AMD on the basis of reaction-rate measurements; and (3) to identify possible alternatives for passive or active treatment of the AMD. The data from this case study ultimately will be used by the National Park Service (NPS) to develop a site remediation plan. The approach used in this study could be applicable at other sites subject to drainage from abandoned coal or metal mines.During April 2004, AMD from 9 sources (sites1, 1Fe, Fe, 2, 3, 3B, 5, 6, and 7) at the ALPO-SBTU test site had a combined flow rate of 1,420 gallons per minute (gal/min) and flow-weighted averages for pH of 3.3, net acidity of 55 milligrams per liter (mg/L) as CaCO3, and concentrations of dissolved sulfate, aluminum, iron, and manganese of 694 mg/L, 4.4 mg/L, 0.74 mg/L, and 1.2 mg/L, respectively. These pH, net acidity, sulfate, and aluminum values exceed effluent criteria for active mines in Pennsylvania.During April-June 2004, limestone and steel slag that were locally available were tested in the laboratory for their composition, approximate surface area, and potential to neutralize samples of the AMD. Although the substrates had a similar particle-size distribution and identical calcium content (43 percent as calcium oxide), the limestone was composed of crystalline carbonates and the slag was composed of silicate glass and minerals. After a minimum of 8 hours contact between the AMD and limestone or steel slag in closed containers (cubitainers), near-neutral effluent was produced. With prolonged contact between the AMD and limestone or steel slag, the concentrations of iron, aluminum, and most dissolved trace elements in effluent from the cubitainers declined while pH was maintained greater than 6.0 and less than 9.0. The cubitainer testing demonstrated (1) lower alkalinity production but higher pH of AMD treated with steel slag compared to limestone, and (2) predictable relations between the effluent quality, detention time, and corresponding flow rate and bulk volume for a bed of crushed limestone or steel slag in an AMD passive-treatment system.The process for evaluating AMD remedial strategies at the ALPO-SBTU test site involved the computation and ranking of the metal loadings during April 2004 for each of the AMD sources and a comparison of the data on AMD flow and chemistry (alkalinity, acidity, dissolved oxygen, ferric iron, aluminum) with published criteria for selection of passive-treatment technology. Although neutralization of the AMD by reaction with limestone was demonstrated with cubitainer tests, an anoxic limestone drain (ALD) was indicated as inappropriate for any AMD source at the test site because all had excessive concentrations of dissolved oxygen and (or) aluminum. One passive-treatment scenario that was identified for the individual or combined AMD sources involved an open limestone channel (OLC) to collect the AMD source(s), a vertical flow compost wetland (VFCW) to add alkalinity, and an aerobic wetland to facilitate iron and manganese oxidation and retention of precipitated solids. Innovative passive-system designs that direct flow upward through submerged layers of limestone and/or steel slag and that incorporate siphons for automatic flushing of solids to a pond also may warrant consideration. Alternatively, an active-treatment system with a hydraulic-powered lime doser could be employed instead of the VFCW or upflow system. Now, given these data on AMD flow and chemistry and identified remedial technologies, a resource manager can use a publicly available computer program such as "AMDTreat" to evaluate the potential sizes and costs of various remedial alternatives.

The availability of second generation feedstocks for the treatment of acid mine drainage and to improve South Africa's bio-based economy.

PubMed

Westensee, Dirk Karl; Rumbold, Karl; Harding, Kevin G; Sheridan, Craig M; van Dyk, Lizelle D; Simate, Geoffrey S; Postma, Ferdinand

2018-10-01

South Africa has a wide range of mining activities making mineral resources important economic commodities. However, the industry is responsible for several environmental impacts; one of which is acid mine drainage (AMD). Despite several years of research, attempts to prevent AMD generation have proven to be difficult. Therefore, treatment of the resulting drainage has been common practice over the years. One of the recommended treatment methods is the use of second generation feedstocks (lignocellulosic biomass). This biomass is also acknowledged to be an important feedstock for bio-refineries as it is abundant, has a high carbon content and is available at minimal cost. It can also potentially be converted to fermentable sugars (e.g. glucose) through different treatment steps, which could further yield other valuable commodities (cellulase, poly-β-hydroxybutyric acid (PHB) and penicillin V). It is estimated by a generic flowsheet model that 7 tons of grass biomass can produce 1400 kg of glucose which can subsequently produce 205 kg, 438 kg and 270 kg of cellulase, PHB and Penicillin V, respectively. In this paper we investigate the feasibility of grass as feedstock for AMD treatment and the subsequent conversion of this acid pre-treated grass into valuable bio-products. Copyright © 2018 Elsevier B.V. All rights reserved.

Unexpected Dominance of Elusive Acidobacteria in Early Industrial Soft Coal Slags

PubMed Central

Wegner, Carl-Eric; Liesack, Werner

2017-01-01

Acid mine drainage (AMD) and mine tailing environments are well-characterized ecosystems known to be dominated by organisms involved in iron- and sulfur-cycling. Here we examined the microbiology of industrial soft coal slags that originate from alum leaching, an ecosystem distantly related to AMD environments. Our study involved geochemical analyses, bacterial community profiling, and shotgun metagenomics. The slags still contained high amounts of alum constituents (aluminum, sulfur), which mediated direct and indirect effects on bacterial community structure. Bacterial groups typically found in AMD systems and mine tailings were not present. Instead, the soft coal slags were dominated by uncharacterized groups of Acidobacteria (DA052 [subdivision 2], KF-JG30-18 [subdivision 13]), Actinobacteria (TM214), Alphaproteobacteria (DA111), and Chloroflexi (JG37-AG-4), which have previously been detected primarily in peatlands and uranium waste piles. Shotgun metagenomics allowed us to reconstruct 13 high-quality Acidobacteria draft genomes, of which two genomes could be directly linked to dominating groups (DA052, KF-JG30-18) by recovered 16S rRNA gene sequences. Comparative genomics revealed broad carbon utilization capabilities for these two groups of elusive Acidobacteria, including polysaccharide breakdown (cellulose, xylan) and the competence to metabolize C1 compounds (ribulose monophosphate pathway) and lignin derivatives (dye-decolorizing peroxidases). Equipped with a broad range of efflux systems for metal cations and xenobiotics, DA052 and KF-JG30-18 may have a competitive advantage over other bacterial groups in this unique habitat. PMID:28642744

Simultaneous chemical oxygen demand removal, methane production and heavy metal precipitation in the biological treatment of landfill leachate using acid mine drainage as sulfate resource.

PubMed

Li, Yu-Long; Wang, Jin; Yue, Zheng-Bo; Tao, Wei; Yang, Hai-Bin; Zhou, Yue-Fei; Chen, Tian-Hu

2017-07-01

Biological treatment played an important role in the treatment of landfill leachate. In the current study, acid mine drainage (AMD) was used as a source of sulfate to strengthen the anaerobic treatment of landfill leachate. Effects of chemical oxygen demand (COD) and SO 4 2- mass concentration ratio on the decomposition of organic matter, methane production and sulfate reduction were investigated and the microbial community was analyzed using the high throughout methods. Results showed that high removal efficiency of COD, methane production and heavy metal removal was achieved when the initial COD/SO 4 2- ratio (based on mass) was set at 3.0. The relative abundance of anaerobic hydrogen-producing bacteria (Candidatus Cloacamonas) in the experimental group with the addition of AMD was significantly increased compared to the control. Abundance of hydrogenotrophic methanogens of Methanosarcina and Methanomassiliicoccus was increased. Results confirmed that AMD could be used as sulfate resource to strengthen the biological treatment of landfill leachate. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

The impacts of neutralized acid mine drainage contaminated water on the expression of selected endocrine-linked genes in juvenile Mozambique tilapia Oreochromis mossambicus exposed in vivo.

PubMed

Truter, Johannes Christoff; va Wyk, Johannes Hendrik; Oberholster, Paul Johan; Botha, Anna-Maria

2014-02-01

Acid mine drainage (AMD) is a global environmental concern due to detrimental impacts on river ecosystems. Little is however known regarding the biological impacts of neutralized AMD on aquatic vertebrates despite excessive discharge into watercourses. The aim of this investigation was to evaluate the endocrine modulatory potential of neutralized AMD, using molecular biomarkers in the teleost fish Oreochromis mossambicus in exposure studies. Surface water was collected from six locations downstream of a high density sludge (HDS) AMD treatment plant and a reference site unimpacted by AMD. The concentrations of 28 elements, including 22 metals, were quantified in the exposure water in order to identify potential links to altered gene expression. Relatively high concentrations of manganese (~ 10mg/l), nickel (~ 0.1mg/l) and cobalt (~ 0.03 mg/l) were detected downstream of the HDS plant. The expression of thyroid receptor-α (trα), trβ, androgen receptor-1 (ar1), ar2, glucocorticoid receptor-1 (gr1), gr2, mineralocorticoid receptor (mr) and aromatase (cyp19a1b) was quantified in juvenile fish after 48 h exposure. Slight but significant changes were observed in the expression of gr1 and mr in fish exposed to water collected directly downstream of the HDS plant, consisting of approximately 95 percent neutralized AMD. The most pronounced alterations in gene expression (i.e. trα, trβ, gr1, gr2, ar1 and mr) was associated with water collected further downstream at a location with no other apparent contamination vectors apart from the neutralized AMD. The altered gene expression associated with the "downstream" locality coincided with higher concentrations of certain metals relative to the locality adjacent to the HDS plant which may indicate a causative link. The current study provides evidence of endocrine disruptive activity associated with neutralized AMD contamination in regard to alterations in the expression of key genes linked to the thyroid, interrenal and gonadal endocrine axes of a teleost fish species. © 2013 Published by Elsevier Inc.

Examining Heavy Metals in Acid Mine Drainage Wetlands in Western Pennsylvania through the use of Inductively Coupled Plasma Optical Emission Spectroscopy and Drone Aerial Photography.

NASA Astrophysics Data System (ADS)

Santoro, N.; Mount, G.

2017-12-01

Acid mine drainage (AMD) emanating from three abandoned mines feed an estimated 126 pounds of iron per day into the Tanoma remediation wetlands located in Tanoma, Pennsylvania. Along with the iron released into the system, 1500-2800 gallons of AMD per minute is seasonally discharged into the passive system. This high rate of discharge produces areas of high velocity flow that scour the wetland bottom moving precipitants and destroying vegetation roots. Although the discharge into Tanoma is known to be damaging, other discharges to surface waters have shown iron and heavy metal concentrations several times higher, and are left untreated to enter reservoir systems. This draws attention to these remediation sites, the processes used to treat them, and the effectiveness of each site. With most of the research that's been conducted in the AMD remediation field relating to in-lab experiments on iron concentrations, there is very little information in the literature about the effects of these large influxes of heavy metals and the effects it has on the biodiversity and methane production within a AMD remediation site. This research investigates the presence and concentration of heavy metals with the treatment wetland and other surface water sources using inductively coupled plasma optical emission spectroscopy (ICP-OES) and drone based aerial photography. Furthermore, our ICP data is compared with biodiversity patterns and methane levels within the Tanoma AMD site to identify relationships and the potential effect they have on the productivity and effectiveness of the remediation site through time.

Recent Developments for Remediating Acidic Mine Waters Using Sulfidogenic Bacteria

PubMed Central

Bitencourt, José A. P.; Sahoo, Prafulla K.; Alves, Joner Oliveira; Siqueira, José O.

2017-01-01

Acidic mine drainage (AMD) is regarded as a pollutant and considered as potential source of valuable metals. With diminishing metal resources and ever-increasing demand on industry, recovering AMD metals is a sustainable initiative, despite facing major challenges. AMD refers to effluents draining from abandoned mines and mine wastes usually highly acidic that contain a variety of dissolved metals (Fe, Mn, Cu, Ni, and Zn) in much greater concentration than what is found in natural water bodies. There are numerous remediation treatments including chemical (lime treatment) or biological methods (aerobic wetlands and compost bioreactors) used for metal precipitation and removal from AMD. However, controlled biomineralization and selective recovering of metals using sulfidogenic bacteria are advantageous, reducing costs and environmental risks of sludge disposal. The increased understanding of the microbiology of acid-tolerant sulfidogenic bacteria will lead to the development of novel approaches to AMD treatment. We present and discuss several important recent approaches using low sulfidogenic bioreactors to both remediate and selectively recover metal sulfides from AMD. This work also highlights the efficiency and drawbacks of these types of treatments for metal recovery and points to future research for enhancing the use of novel acidophilic and acid-tolerant sulfidogenic microorganisms in AMD treatment. PMID:29119111

Removal of heavy metals from acid mine drainage using chicken eggshells in column mode.

PubMed

Zhang, Ting; Tu, Zhihong; Lu, Guining; Duan, Xingchun; Yi, Xiaoyun; Guo, Chuling; Dang, Zhi

2017-03-01

Chicken eggshells (ES) as alkaline sorbent were immobilized in a fixed bed to remove typical heavy metals from acid mine drainage (AMD). The obtained breakthrough curves showed that the breakthrough time increased with increasing bed height, but decreased with increasing flow rate and increasing particle size. The Thomas model and bed depth service time model could accurately predict the bed dynamic behavior. At a bed height of 10 cm, a flow rate of 10 mL/min, and with ES particle sizes of 0.18-0.425 mm, for a multi-component heavy metal solution containing Cd 2+ , Pb 2+ and Cu 2+ , the ES capacities were found to be 1.57, 146.44 and 387.51 mg/g, respectively. The acidity of AMD effluent clearly decreased. The ES fixed-bed showed the highest removal efficiency for Pb with a better adsorption potential. Because of the high concentration in AMD and high removal efficiency in ES fixed-bed of iron ions, iron floccules (Fe 2 (OH) 2 CO 3 ) formed and obstructed the bed to develop the overall effectiveness. The removal process was dominated by precipitation under the alkaline reaction of ES, and the co-precipitation of heavy metals with iron ions. The findings of this work will aid in guiding and optimizing pilot-scale application of ES to AMD treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Temperature and nutrients as drivers of microbially mediated arsenic oxidation and removal from acid mine drainage.

PubMed

Tardy, Vincent; Casiot, Corinne; Fernandez-Rojo, Lidia; Resongles, Eléonore; Desoeuvre, Angélique; Joulian, Catherine; Battaglia-Brunet, Fabienne; Héry, Marina

2018-03-01

Microbial oxidation of iron (Fe) and arsenic (As) followed by their co-precipitation leads to the natural attenuation of these elements in As-rich acid mine drainage (AMD). The parameters driving the activity and diversity of bacterial communities responsible for this mitigation remain poorly understood. We conducted batch experiments to investigate the effect of temperature (20 vs 35 °C) and nutrient supply on the rate of Fe and As oxidation and precipitation, the bacterial diversity (high-throughput sequencing of 16S rRNA gene), and the As oxidation potential (quantification of aioA gene) in AMD from the Carnoulès mine (France). In batch incubated at 20 °C, the dominance of iron-oxidizing bacteria related to Gallionella spp. was associated with almost complete iron oxidation (98%). However, negligible As oxidation led to the formation of As(III)-rich precipitates. Incubation at 35 °C and nutrient supply both stimulated As oxidation (71-75%), linked to a higher abundance of aioA gene and the dominance of As-oxidizing bacteria related to Thiomonas spp. As a consequence, As(V)-rich precipitates (70-98% of total As) were produced. Our results highlight strong links between indigenous bacterial community composition and iron and arsenic removal efficiency within AMD and provide new insights for the future development of a biological treatment of As-rich AMD.

Fe(II) oxidation during acid mine drainage neutralization in a pilot-scale Sequencing Batch Reactor.

PubMed

Zvimba, J N; Mathye, M; Vadapalli, V R K; Swanepoel, H; Bologo, L

2013-01-01

This study investigated Fe(II) oxidation during acid mine drainage (AMD) neutralization using CaCO3 in a pilot-scale Sequencing Batch Reactor (SBR) of hydraulic retention time (HRT) of 90 min and sludge retention time (SRT) of 360 min in the presence of air. The removal kinetics of Fe(II), of initial concentration 1,033 ± 0 mg/L, from AMD through oxidation to Fe(III) was observed to depend on both pH and suspended solids, resulting in Fe(II) levels of 679 ± 32, 242 ± 64, 46 ± 16 and 28 ± 0 mg/L recorded after cycles 1, 2, 3 and 4 respectively, with complete Fe(II) oxidation only achieved after complete neutralization of AMD. Generally, it takes 30 min to completely oxidize Fe(II) during cycle 4, suggesting that further optimization of SBR operation based on both pH and suspended solids manipulation can result in significant reduction of the number of cycles required to achieve acceptable Fe(II) oxidation for removal as ferric hydroxide. Overall, complete removal of Fe(II) during AMD neutralization is attractive as it promotes recovery of better quality waste gypsum, key to downstream gypsum beneficiation for recovery of valuables, thereby enabling some treatment-cost recovery and prevention of environmental pollution from dumping of sludge into landfills.

Geochemical characteristics of dissolved rare earth elements in acid mine drainage from abandoned high-As coal mining area, southwestern China.

PubMed

Li, Xuexian; Wu, Pan

2017-09-01

Acid mine drainage (AMD) represents a major source of water pollution in the small watershed of Xingren coalfield in southwestern Guizhou Province. A detailed geochemical study was performed to investigate the origin, distribution, and migration of REEs by determining the concentrations of REEs and major solutes in AMD samples, concentrations of REEs in coal, bedrocks, and sediment samples, and modeling REEs aqueous species. The results highlighted that all water samples collected in the mining area are identified as low pH, high concentrations of Fe, Al, SO 4 2- and distinctive As and REEs. The spatial distributions of REEs showed a peak in where it is nearby the location of discharging of AMD, and then decrease significantly with distance away from the mining areas. Lots of labile REEs have an origin of coal and bedrocks, whereas the acid produced by the oxidation of pyrite is a prerequisite to cause the dissolution of coal and bedrocks, and then promoting REEs release in AMD. The North American Shale Composite (NASC)-normalized REE patterns of coal and bedrocks are enriched in light REEs (LREEs) and middle REEs (MREEs) relative to heavy REEs (HREEs). Contrary to these solid samples, AMD samples showed slightly enrichment of MREEs compared with LREEs and HREEs. This behavior implied that REEs probably fractionate during acid leaching, dissolution of bedrocks, and subsequent transport, so that the MREEs is primarily enriched in AMD samples. Calculation of REEs inorganic species for AMD demonstrated that sulfate complexes (Ln(SO 4 ) + and Ln(SO 4 ) 2 - ) predominate in these species, accounting for most of proportions for the total REEs species. The high concentrations of dissolved SO 4 2- and low pH play a decisive role in controlling the presence of REEs in AMD, as these conditions are necessary for formation of stable REEs-sulfate complexes in current study. The migration and transportation of REEs in AMD are more likely constrained by adsorption and co-precipitation of Fe-Al hydroxides/hydroxysulfate. In addition, the MREEs is preferentially captured by poorly crystalline Fe-Al hydroxides/hydroxysulfate, which favors that sediments also preserve NASC-normalized patterns with MREEs enrichment in the stream.

Incorporating Geochemical And Microbial Kinetics In Reactive Transport Models For Generation Of Acid Rock Drainage

NASA Astrophysics Data System (ADS)

Andre, B. J.; Rajaram, H.; Silverstein, J.

2010-12-01

Acid mine drainage, AMD, results from the oxidation of metal sulfide minerals (e.g. pyrite), producing ferrous iron and sulfuric acid. Acidophilic autotrophic bacteria such as Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans obtain energy by oxidizing ferrous iron back to ferric iron, using oxygen as the electron acceptor. Most existing models of AMD do not account for microbial kinetics or iron geochemistry rigorously. Instead they assume that oxygen limitation controls pyrite oxidation and thus focus on oxygen transport. These models have been successfully used for simulating conditions where oxygen availability is a limiting factor (e.g. source prevention by capping), but have not been shown to effectively model acid generation and effluent chemistry under a wider range of conditions. The key reactions, oxidation of pyrite and oxidation of ferrous iron, are both slow kinetic processes. Despite being extensively studied for the last thirty years, there is still not a consensus in the literature about the basic mechanisms, limiting factors or rate expressions for microbially enhanced oxidation of metal sulfides. An indirect leaching mechanism (chemical oxidation of pyrite by ferric iron to produce ferrous iron, with regeneration of ferric iron by microbial oxidation of ferrous iron) is used as the foundation of a conceptual model for microbially enhanced oxidation of pyrite. Using literature data, a rate expression for microbial consumption of ferrous iron is developed that accounts for oxygen, ferrous iron and pH limitation. Reaction rate expressions for oxidation of pyrite and chemical oxidation of ferrous iron are selected from the literature. A completely mixed stirred tank reactor (CSTR) model is implemented coupling the kinetic rate expressions, speciation calculations and flow. The model simulates generation of AMD and effluent chemistry that qualitatively agrees with column reactor and single rock experiments. A one dimensional reaction diffusion model at the scale of a single rock is developed incorporating the proposed kinetic rate expressions. Simulations of initiation, washout and AMD flows are discussed to gain a better understanding of the role of porosity, effective diffusivity and reactive surface area in generating AMD. Simulations indicate that flow boundary conditions control generation of acid rock drainage as porosity increases.

Mine Waste at The Kherzet Youcef Mine : Environmental Characterization

NASA Astrophysics Data System (ADS)

Issaad, Mouloud; Boutaleb, Abdelhak; Kolli, Omar

2017-04-01

Mining activity in Algeria has existed since antiquity. But it was very important since the 20th century. This activity has virtually ceased since the beginning of the 1990s, leaving many mine sites abandoned (so-called orphan mines). The abandonment of mining today poses many environmental problems (soil pollution, contamination of surface water, mining collapses...). The mining wastes often occupy large volumes that can be hazardous to the environment and human health, often neglected in the past: Faulting geotechnical implementation, acid mine drainage (AMD), alkalinity, presence of pollutants and toxic substances (heavy metals, cyanide...). The study started already six years ago and it covers all mines located in NE Algeria, almost are stopped for more than thirty years. So the most important is to have an overview of all the study area. After the inventory job of the abandoned mines, the rock drainage prediction will help us to classify sites according to their acid generating potential.

Development of a diatom-based multimetric index for acid mine drainage impacted depressional wetlands.

PubMed

Riato, Luisa; Leira, Manel; Della Bella, Valentina; Oberholster, Paul J

2018-01-15

Acid mine drainage (AMD) from coal mining in the Mpumalanga Highveld region of South Africa has caused severe chemical and biological degradation of aquatic habitats, specifically depressional wetlands, as mines use these wetlands for storage of AMD. Diatom-based multimetric indices (MMIs) to assess wetland condition have mostly been developed to assess agricultural and urban land use impacts. No diatom MMI of wetland condition has been developed to assess AMD impacts related to mining activities. Previous approaches to diatom-based MMI development in wetlands have not accounted for natural variability. Natural variability among depressional wetlands may influence the accuracy of MMIs. Epiphytic diatom MMIs sensitive to AMD were developed for a range of depressional wetland types to account for natural variation in biological metrics. For this, we classified wetland types based on diatom typologies. A range of 4-15 final metrics were selected from a pool of ~140 candidate metrics to develop the MMIs based on their: (1) broad range, (2) high separation power and (3) low correlation among metrics. Final metrics were selected from three categories: similarity to reference sites, functional groups, and taxonomic composition, which represent different aspects of diatom assemblage structure and function. MMI performances were evaluated according to their precision in distinguishing reference sites, responsiveness to discriminate reference and disturbed sites, sensitivity to human disturbances and relevancy to AMD-related stressors. Each MMI showed excellent discriminatory power, whether or not it accounted for natural variation. However, accounting for variation by grouping sites based on diatom typologies improved overall performance of MMIs. Our study highlights the usefulness of diatom-based metrics and provides a model for the biological assessment of depressional wetland condition in South Africa and elsewhere. Copyright © 2017 Elsevier B.V. All rights reserved.

Passive bioremediation technology incorporating lignocellulosic spent mushroom compost and limestone for metal- and sulfate-rich acid mine drainage.

PubMed

Muhammad, Siti Nurjaliah; Kusin, Faradiella Mohd; Md Zahar, Mohd Syakirin; Mohamat Yusuff, Ferdaus; Halimoon, Normala

2017-08-01

Passive bioremediation of metal- and sulfate-containing acid mine drainage (AMD) has been investigated in a batch study. Multiple substrates were used in the AMD remediation using spent mushroom compost (SMC), limestone, activated sludge (AS), and woodchips (WC) under anoxic conditions suitable for bacterial sulfate reduction (BSR). Limestones used were of crushed limestone (CLS) and uncrushed limestone, provided at two different ratios in mixed substrates treatment and varied by the proportion of SMC and limestone. The SMC greatly assisted the removals of sulfate and metals and also acted as an essential carbon source for BSR. The mixed substrate composed of 40% CLS, 30% SMC, 20% AS, and 10% WC was found to be effective for metal removal. Mn, Cu, Pb, and Zn were greatly removed (89-100%) in the mixed substrates treatment, while Fe was only removed at 65%. Mn was found to be removed at a greatly higher rate than Fe, suggesting important Mn adsorption onto organic materials, that is, greater sorption affinity to the SMC. Complementary with multiple treatment media was the main mechanism assisting the AMD treatment through microbial metal reduction reactions.

Water quality changes in acid mine drainage streams in Gangneung, Korea, 10 years after treatment with limestone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shim, Moo Joon; Choi, Byoung Young; Lee, Giehyeon

To determine the long-term effectiveness of the limestone treatment for acid mine drainage (AMD) in Gangneung, Korea, we investigated the elemental distribution in streams impacted by AMD and compared the results of previous studies before and approximately 10 years after the addition of limestone. Addition of limestone in 1999 leads to a pH increase in 2008, and with the exception of Ca, the elemental concentrations (e.g., Fe, Mn, Mg, Sr, Ni, Zn, S) in the streams decreased. The pH was 2.5–3 before the addition of limestone and remained stable at around 4.5–5 from 2008 to 2011, suggesting the reactivity ofmore » the added limestone was diminished and that an alternative approach is needed to increase the pH up to circumneutral range and maintain effective long-term treatment. To identify the processes causing the decrease in the elemental concentrations, we also examined the spatial (approximately 7 km) distribution over three different types of streams affected by the AMD. Lastly, the elemental distribution was mainly controlled by physicochemical processes including redox reactions, dilution on mixing, and co-precipitation/adsorption with Fe (hydr)oxides.« less

Regeneration of barium carbonate from barium sulphide in a pilot-scale bubbling column reactor and utilization for acid mine drainage.

PubMed

Mulopo, J; Zvimba, J N; Swanepoel, H; Bologo, L T; Maree, J

2012-01-01

Batch regeneration of barium carbonate (BaCO(3)) from barium sulphide (BaS) slurries by passing CO(2) gas into a pilot-scale bubbling column reactor under ambient conditions was used to assess the technical feasibility of BaCO(3) recovery in the Alkali Barium Calcium (ABC) desalination process and its use for sulphate removal from high sulphate Acid Mine Drainage (AMD). The effect of key process parameters, such as BaS slurry concentration and CO(2) flow rate on the carbonation, as well as the extent of sulphate removal from AMD using the recovered BaCO(3) were investigated. It was observed that the carbonation reaction rate for BaCO(3) regeneration in a bubbling column reactor significantly increased with increase in carbon dioxide (CO(2)) flow rate whereas the BaS slurry content within the range 5-10% slurry content did not significantly affect the carbonation rate. The CO(2) flow rate also had an impact on the BaCO(3) morphology. The BaCO(3) recovered from the pilot-scale bubbling column reactor demonstrated effective sulphate removal ability during AMD treatment compared with commercial BaCO(3).

Spatio-Temporal Detection of the Thiomonas Population and the Thiomonas Arsenite Oxidase Involved in Natural Arsenite Attenuation Processes in the Carnoulès Acid Mine Drainage

PubMed Central

Hovasse, Agnès; Bruneel, Odile; Casiot, Corinne; Desoeuvre, Angélique; Farasin, Julien; Hery, Marina; Van Dorsselaer, Alain; Carapito, Christine; Arsène-Ploetze, Florence

2016-01-01

The acid mine drainage (AMD) impacted creek of the Carnoulès mine (Southern France) is characterized by acid waters with a high heavy metal content. The microbial community inhabiting this AMD was extensively studied using isolation, metagenomic and metaproteomic methods, and the results showed that a natural arsenic (and iron) attenuation process involving the arsenite oxidase activity of several Thiomonas strains occurs at this site. A sensitive quantitative Selected Reaction Monitoring (SRM)-based proteomic approach was developed for detecting and quantifying the two subunits of the arsenite oxidase and RpoA of two different Thiomonas groups. Using this approach combined with FISH and pyrosequencing-based 16S rRNA gene sequence analysis, it was established here for the first time that these Thiomonas strains are ubiquitously present in minor proportions in this AMD and that they express the key enzymes involved in natural remediation processes at various locations and time points. In addition to these findings, this study also confirms that targeted proteomics applied at the community level can be used to detect weakly abundant proteins in situ. PMID:26870729

Single-cell sequencing unveils the lifestyle and CRISPR-based population history of Hydrotalea sp. in acid mine drainage.

PubMed

Medeiros, J D; Leite, L R; Pylro, V S; Oliveira, F S; Almeida, V M; Fernandes, G R; Salim, A C M; Araújo, F M G; Volpini, A C; Oliveira, G; Cuadros-Orellana, S

2017-10-01

Acid mine drainage (AMD) is characterized by an acid and metal-rich run-off that originates from mining systems. Despite having been studied for many decades, much remains unknown about the microbial community dynamics in AMD sites, especially during their early development, when the acidity is moderate. Here, we describe draft genome assemblies from single cells retrieved from an early-stage AMD sample. These cells belong to the genus Hydrotalea and are closely related to Hydrotalea flava. The phylogeny and average nucleotide identity analysis suggest that all single amplified genomes (SAGs) form two clades that may represent different strains. These cells have the genomic potential for denitrification, copper and other metal resistance. Two coexisting CRISPR-Cas loci were recovered across SAGs, and we observed heterogeneity in the population with regard to the spacer sequences, together with the loss of trailer-end spacers. Our results suggest that the genomes of Hydrotalea sp. strains studied here are adjusting to a quickly changing selective pressure at the microhabitat scale, and an important form of this selective pressure is infection by foreign DNA. © 2017 John Wiley & Sons Ltd.

Effect of an acid mine drainage effluent on phytoplankton biomass and primary production at Britannia Beach, Howe Sound, British Columbia.

PubMed

Levings, C D; Varela, D E; Mehlenbacher, N M; Barry, K L; Piercey, G E; Guo, M; Harrison, P J

2005-12-01

We investigated the effect of acid mine drainage (AMD) from an abandoned copper mine at Britannia Beach (Howe Sound, BC, Canada) on primary productivity and chlorophyll a levels in the receiving waters of Howe Sound before, during, and after freshet from the Squamish River. Elevated concentrations of copper (integrated average through the water column >0.050 mgl(-1)) in nearshore waters indicated that under some conditions a small gyre near the mouth of Britannia Creek may have retained the AMD from Britannia Creek and from a 30-m deep water outfall close to shore. Regression and correlation analyses indicated that copper negatively affected primary productivity during April (pre-freshet) and November (post-freshet). Negative effects of copper on primary productivity were not supported statistically for July (freshet), possibly because of additional effects such as turbidity from the Squamish River. Depth-integrated average and surface chlorophyll a were correlated to copper concentrations in April. During this short study we demonstrated that copper concentrations from the AMD discharge can negatively affect both primary productivity and the standing stock of primary producers in Howe Sound.

Water quality changes in acid mine drainage streams in Gangneung, Korea, 10 years after treatment with limestone

DOE PAGES

Shim, Moo Joon; Choi, Byoung Young; Lee, Giehyeon; ...

2015-09-28

To determine the long-term effectiveness of the limestone treatment for acid mine drainage (AMD) in Gangneung, Korea, we investigated the elemental distribution in streams impacted by AMD and compared the results of previous studies before and approximately 10 years after the addition of limestone. Addition of limestone in 1999 leads to a pH increase in 2008, and with the exception of Ca, the elemental concentrations (e.g., Fe, Mn, Mg, Sr, Ni, Zn, S) in the streams decreased. The pH was 2.5–3 before the addition of limestone and remained stable at around 4.5–5 from 2008 to 2011, suggesting the reactivity ofmore » the added limestone was diminished and that an alternative approach is needed to increase the pH up to circumneutral range and maintain effective long-term treatment. To identify the processes causing the decrease in the elemental concentrations, we also examined the spatial (approximately 7 km) distribution over three different types of streams affected by the AMD. Lastly, the elemental distribution was mainly controlled by physicochemical processes including redox reactions, dilution on mixing, and co-precipitation/adsorption with Fe (hydr)oxides.« less

Evaluating expected outcomes of acid remediation in an intensively mined Appalachian watershed.

PubMed

Watson, Andrew S; Merovich, George T; Petty, J Todd; Gutta, J Brady

2017-07-01

Assessments of watershed-based restoration efforts are rare but are essential for the science of stream restoration to advance. We conducted a watershed scale assessment of Abram Creek before and after implementation of a watershed-based plan designed to maximize ecological recovery from acid mine drainage (AMD) impairment. We surveyed water chemistry, physical habitat, benthic macroinvertebrates, and fish community structure in three stream types: AMD-impacted (14 streams), AMD-treated (13 streams), and unimpaired reference (4 streams). We used in-stream measurements to quantify ecological loss from AMD, the amount of ecological recovery expected through remediation, and the observed degree of post-treatment recovery. Sites impaired by AMD improved in water quality with AMD treatment. Dissolved metals and acidity declined significantly in treated streams, but sulfate and specific conductance did not. Likewise, sites impaired by AMD improved in bio-condition scores with AMD treatment. EPT genera increased significantly but were lower compared to unimpaired streams. We found fish at nine treated sites that had none before treatment. Community-level analyses indicated improved but altered assemblages with AMD treatment. Analysis of pre-treatment conditions indicated that only 30% of the historic fishery remained. Remediation was expected to recover 66% of the historic fishery value, and assessment of post-treatment conditions indicates that 52% of the historic fishery has been recovered after 3 years. Developing expected endpoints for restoration outcomes provides a tool to objectively evaluate successes and can guide adaptive management strategies.

Concentration-Discharge Behavior of Contaminants in a Stream Impacted by Acid Mine Drainage

NASA Astrophysics Data System (ADS)

Shaw, M. E.; Klein, M.; Herndon, E.

2017-12-01

Acid mine drainage (AMD) has severely degraded streams throughout the Appalachian coal region of the United States. AMD occurs when pyrite contained in coal is exposed to water and air during mining activities and oxidized to release high concentrations of sulfate, metals, and acidity into water bodies. Little is known about the concentration-discharge (CQ) relationships of solutes in AMD-impacted streams due to the complicated nature of acid mine drainage systems. For example, streams may receive inputs from multiple sources that include runoff, constructed treatment systems, and abandoned mines that bypass these systems to continue to contaminate the streams. It is important to understand the CQ relationships of contaminants in AMD-impacted streams in order to elucidate contaminant sources and to predict effects on aquatic ecosystems. Here, we study the CQ behaviors of acid and metals in a contaminated watershed in northeastern Ohio where limestone channels have been installed to remediate water draining from a mine pool into the stream. Stream chemistry was measured in samples collected once per day or once per hour during storm events, and stream flow was measured continuously at the watershed outlet. Increases in stream velocity during storm events resulted in an increase in pH (from 3 to 6) that subsequently decreased back to 3 as flow decreased. Additionally, Fe and Mn concentrations in the stream were high during baseflow (7 and 15 mg/L, respectively) and decreased with increasing discharge during storm events. These results indicate that the treatment system is only effective at neutralizing stream acidity and removing metals when water flow through the limestone channel is continuous. We infer that the acidic and metal-rich baseflow derives from upwelling of contaminated groundwater or subsurface flow from a mine pool. Ongoing studies aim to isolate the source of this baseflow contamination and evaluate the geochemical transformations that occur as it flows into the stream.

Influences of acid mine drainage and thermal enrichment on stream fish reproduction and larval survival

USGS Publications Warehouse

Hafs, Andrew W.; Horn, C.D.; Mazik, P.M.; Hartman, K.J.

2010-01-01

Potential effects of acid mine drainage (AMD) and thermal enrichment on the reproduction of fishes were investigated through a larval-trapping survey in the Stony River watershed, Grant County, WV. Trapping was conducted at seven sites from 26 March to 2 July 2004. Overall larval catch was low (379 individuals in 220 hours of trapping). More larval White Suckers were captured than all other species. Vectors fitted to nonparametric multidimensional scaling ordinations suggested that temperature was highly correlated to fish communities captured at our sites. Survival of larval Fathead Minnows was examined in situ at six sites from 13 May to 11 June 2004 in the same system. Larval survival was lower, but not significantly different between sites directly downstream of AMD-impacted tributaries (40% survival) and non-AMD sites (52% survival). The lower survival was caused by a significant mortality event at one site that coincided with acute pH depression in an AMD tributary immediately upstream of the site. Results from a Cox proportional hazard test suggests that low pH is having a significant negative influence on larval fish survival in this system. The results from this research indicate that the combination of low pH events and elevated temperature are negatively influencing the larval fish populations of the Stony River watershed. Management actions that address these problems would have the potential to substantially increase both reproduction rates and larval survival, therefore greatly enhancing the fishery.

RubisCO Gene Clusters Found in a Metagenome Microarray from Acid Mine Drainage

PubMed Central

Guo, Xue; Yin, Huaqun; Cong, Jing; Dai, Zhimin; Liang, Yili

2013-01-01

The enzyme responsible for carbon dioxide fixation in the Calvin cycle, ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO), is always detected as a phylogenetic marker to analyze the distribution and activity of autotrophic bacteria. However, such an approach provides no indication as to the significance of genomic content and organization. Horizontal transfers of RubisCO genes occurring in eubacteria and plastids may seriously affect the credibility of this approach. Here, we presented a new method to analyze the diversity and genomic content of RubisCO genes in acid mine drainage (AMD). A metagenome microarray containing 7,776 large-insertion fosmids was constructed to quickly screen genome fragments containing RubisCO form I large-subunit genes (cbbL). Forty-six cbbL-containing fosmids were detected, and six fosmids were fully sequenced. To evaluate the reliability of the metagenome microarray and understand the microbial community in AMD, the diversities of cbbL and the 16S rRNA gene were analyzed. Fosmid sequences revealed that the form I RubisCO gene cluster could be subdivided into form IA and IB RubisCO gene clusters in AMD, because of significant divergences in molecular phylogenetics and conservative genomic organization. Interestingly, the form I RubisCO gene cluster coexisted with the form II RubisCO gene cluster in one fosmid genomic fragment. Phylogenetic analyses revealed that horizontal transfers of RubisCO genes may occur widely in AMD, which makes the evolutionary history of RubisCO difficult to reconcile with organismal phylogeny. PMID:23335778

Microbial Diversity and Its Relationship to Physicochemical Characteristics of the Water in Two Extreme Acidic Pit Lakes from the Iberian Pyrite Belt (SW Spain)

PubMed Central

López-Pamo, Enrique; Gomariz, María; Amils, Ricardo; Aguilera, Ángeles

2013-01-01

The Iberian Pyrite Belt (IPB) hosts one of the world’s largest accumulations of acidic mine wastes and pit lakes. The mineralogical and textural characteristics of the IPB ores have favored the oxidation and dissolution of metallic sulfides, mainly pyrite, and the subsequent formation of acidic mining drainages. This work reports the physical properties, hydrogeochemical characteristics, and microbial diversity of two pit lakes located in the IPB. Both pit lakes are acidic and showed high concentrations of sulfate and dissolved metals. Concentrations of sulfate and heavy metals were higher in the Nuestra Señora del Carmen lake (NSC) by one order of magnitude than in the Concepción (CN) lake. The hydrochemical characteristics of NSC were typical of acid mine waters and can be compared with other acidic environments. When compared to other IPB acidic pit lakes, the superficial water of CN is more diluted than that of any of the others due, probably, to the strong influence of runoff water. Both pit lakes showed chemical and thermal stratification with well defined chemoclines. One particular characteristic of NSC is that it has developed a chemocline very close to the surface (2 m depth). Microbial community composition of the water column was analyzed by 16S and 18S rRNA gene cloning and sequencing. The microorganisms detected in NSC were characteristic of acid mine drainage (AMD), including iron oxidizing bacteria (Leptospirillum, Acidithiobacillus ferrooxidans) and facultative iron reducing bacteria and archaea (Acidithiobacillus ferrooxidans, Acidiphilium, Actinobacteria, Acidimicrobiales, Ferroplasma) detected in the bottom layer. Diversity in CN was higher than in NSC. Microorganisms known from AMD systems (Acidiphilium, Acidobacteria and Ferrovum) and microorganisms never reported from AMD systems were identified. Taking into consideration the hydrochemical characteristics of these pit lakes and the spatial distribution of the identified microorganisms, a model explaining their geomicrobiology is advanced. PMID:23840525

Mineralogical and geochemical characterization of waste rocks from a gold mine in northeastern Thailand: application for environmental impact protection.

PubMed

Assawincharoenkij, Thitiphan; Hauzenberger, Christoph; Ettinger, Karl; Sutthirat, Chakkaphan

2018-02-01

Waste rocks from gold mining in northeastern Thailand are classified as sandstone, siltstone, gossan, skarn, skarn-sulfide, massive sulfide, diorite, and limestone/marble. Among these rocks, skarn-sulfide and massive sulfide rocks have the potential to generate acid mine drainage (AMD) because they contain significant amounts of sulfide minerals, i.e., pyrrhotite, pyrite, arsenopyrite, and chalcopyrite. Moreover, both sulfide rocks present high contents of As and Cu, which are caused by the occurrence of arsenopyrite and chalcopyrite, respectively. Another main concern is gossan contents, which are composed of goethite, hydrous ferric oxide (HFO), quartz, gypsum, and oxidized pyroxene. X-ray maps using electron probe micro-analysis (EPMA) indicate distribution of some toxic elements in Fe-oxyhydroxide minerals in the gossan waste rock. Arsenic (up to 1.37 wt.%) and copper (up to 0.60 wt.%) are found in goethite, HFO, and along the oxidized rim of pyroxene. Therefore, the gossan rock appears to be a source of As, Cu, and Mn. As a result, massive sulfide, skarn-sulfide, and gossan have the potential to cause environmental impacts, particularly AMD and toxic element contamination. Consequently, the massive sulfide and skarn-sulfide waste rocks should be protected from oxygen and water to avoid an oxidizing environment, whereas the gossan waste rocks should be protected from the formation of AMD to prevent heavy metal contamination.

Acid mine treatment with open limestone channels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ziemkiewicz, P.F.; Brant, D.L.; Skousen, J.G.

1996-12-31

Acid mine drainage (AMD) is often associated with mining of pyritic coal and metal deposits. Typical AMD associated with coal mines in the eastern US can have acidity and iron concentrations ranging from the teens to the thousands of mg/l. Aluminum and manganese can be present in concentrations ranging from zero to the low hundreds of mg/l. Much attention has been devoted to developing inexpensive, limestone (LS)-based systems for treating AMID with little or no maintenance. However, LS tends to coat with metal hydroxides when exposed to AMID in an oxidized state, a process known as {open_quotes}armoring{close_quotes}. It is generallymore » assumed that once armored, LS ceases to neutralize acid. Another problem is that the hydroxides tend to settle into plug the pore spaces in LS beds forcing water to move around rather than through the LS. While both are caused by the precipitation of metal hydroxides, armoring and plugging are two different problems. Plugging of LS pores can be avoided by maintaining a high flushing rate through the LS bed. Armoring, however, occurs regardless of water velocity. This study investigated the influence of armoring on LS solubility and the implications of armoring and plugging on the construction of open (oxidizing) LS channels for treating AMD. We evaluated the AMID treatment performance of armored and unarmored LS in oxidizing environments both in laboratory and field studies.« less

Integrated acid mine drainage management using fly ash.

PubMed

Vadapalli, Viswanath R K; Gitari, Mugera W; Petrik, Leslie F; Etchebers, Olivier; Ellendt, Annabelle

2012-01-01

Fly Ash (FA) from a power station in South Africa was investigated to neutralise and remove contaminants from Acid Mine Drainage (AMD). After this primary treatment the insoluble FA residue namely solid residue (SR) was investigated as a suitable mine backfill material by means of strength testing. Moreover, SR was used to synthesise zeolite-P using a two-step synthesis procedure. Furthermore, the zeolite-P was investigated to polish process water from the primary FA-AMD reaction. The main objective of this series of investigations is to achieve zero waste and to propose an integrated AMD management using FA. Fly Ash was mixed with AMD at various predetermined FA-AMD ratios until the mixtures achieved circumneutral pH or higher. The supernatants were then analyzed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Ion Chromatography (IC) for cations and anions respectively. The physical strength testing of SR was carried out by mixing it with 3% Ordinary Portland Cement (OPC) and curing for 410 days. Synthesis of zeolite-P using SR was carried out by two step synthesis procedure: ageing for 24 hours followed by a mild hydrothermal synthesis at 100°C for 4 days. The polishing of process water from primary AMD treatment using FA was ascertained by mixing the process water with zeolite at a liquid to solid ratio of 100:1 for 1 hour. The results indicated that FA can be successfully used to ameliorate AMD. High removal of major AMD contaminants Fe, Al, Mg, Mn and sulphate was achieved with the ash treatment and trace elements such as Zn, Ni, Cu and Pb were also removed by the FA. Strength testing over 410 days indicated that the material gained strength over the testing period. The maximum unconfined compressive strength and elastic modulus was observed to be approximately 0.3 MPa and 150 Mpa respectively. The X-ray diffraction (XRD) analysis of the synthesized product indicated that SR was successfully converted into zeolite-P with some mullite phase remaining as a result of incomplete conversion of the feedstock SR. The zeolite-P was used as an ion exchange material to remove selective elements from the process water. Elements such as Ca, Sr, Ba and V were successfully removed from the process water with the zeolite-P. Only marginal removal of Mo was observed during the experiments. It was also observed that Na was exchanged into the solution. This study successfully demonstrated zero waste concepts and an integrated AMD management scheme using FA was developed in this study. The implementation of this technology will address FA storage problem as well as costs associated with AMD treatment.

Stable sulfur and oxygen isotopes as geochemical tracers of sulfate in karst waters

NASA Astrophysics Data System (ADS)

Sun, Jing; Kobayashi, Tatsuaki; Strosnider, William H. J.; Wu, Pan

2017-08-01

Karst water resources, which are extremely sensitive to mining activities, are critical for the support of human societies and ecological systems in many regions worldwide. In order to determine the sources and fate of dissolved sulfate in low-pH karst waters, hydrochemical variations of karst waters with and without acid mine drainage (AMD) impacts were investigated along with stable isotope dynamics. As expected, hydrochemical characteristics and isotopic compositions of the AMD and AMD-downstream water (ADW) were dramatically different from that of the non-AMD-impacted water (NAW). The sources of sulfur isotopes in sulfate were predominantly pyrite oxidation for the AMD and ADW, and atmospheric deposition for the NAW. Based on the general isotope-balance model, the relative proportions of sulfate oxygen derived from water and air were calculated. The mean proportion of sulfate oxygen derived from water in ADW was roughly double that of AMD. This suggests that the sulfate associated with AMD is predominantly influenced by aerobic pyrite oxidation, while that of ADW is likely affected by the dissolution of pyrite under anaerobic conditions in reservoir sediment. This observation was coincident with the noted variations of hydrochemical characteristics and was supported by principal component analysis. These results provide a better understanding of how stable isotopes of sulfate and water can be used to track mining contamination in karst aquifers, which could benefit remediation planning for these distinctive systems.

Impact of AMD on water quality in critical watershed in the Hudson River drainage basin: Phillips Mine, Hudson Highlands, New York

USGS Publications Warehouse

Gilchrist, S.; Gates, A.; Szabo, Z.; Lamothe, P.J.

2009-01-01

A sulfur and trace element enriched U-Th-laced tailings pile at the abandoned Phillips Mine in Garrison, New York, releases acid mine drainage (AMD, generally pH < 3, minimum pH 1.78) into the first-order Copper Mine Brook (CMB) that drains into the Hudson River. The pyrrhotite-rich Phillips Mine is located in the Highlands region, a critical water source for the New York metro area. A conceptual model for derivation/dissolution, sequestration, transport and dilution of contaminants is proposed. The acidic water interacts with the tailings, leaching and dissolving the trace metals. AMD evaporation during dry periods concentrates solid phase trace metals and sulfate, forming melanterite (FeSO4.7H2O) on sulfide-rich tailings surfaces. Wet periods dissolve these concentrates/precipitates, releasing stored acidity and trace metals into the CMB. Sediments along CMB are enriched in iron hydroxides which act as sinks for metals, indicating progressive sequestration that correlates with dilution and sharp rise in pH when mine water mixes with tributaries. Seasonal variations in metal concentrations were partly attributable to dissolution of the efflorescent salts with their sorbed metals and additional metals from surging acidic seepage induced by precipitation.

Effects of remediation on the bacterial community of an acid mine drainage impacted stream.

PubMed

Ghosh, Suchismita; Moitra, Moumita; Woolverton, Christopher J; Leff, Laura G

2012-11-01

Acid mine drainage (AMD) represents a global threat to water resources, and as such, remediation of AMD-impacted streams is a common practice. During this study, we examined bacterial community structure and environmental conditions in a low-order AMD-impacted stream before, during, and after remediation. Bacterial community structure was examined via polymerase chain reaction amplification of 16S rRNA genes followed by denaturing gradient gel electrophoresis. Also, bacterial abundance and physicochemical data (including metal concentrations) were collected and relationships to bacterial community structure were determined using BIO-ENV analysis. Remediation of the study stream altered environmental conditions, including pH and concentrations of some metals, and consequently, the bacterial community changed. However, remediation did not necessarily restore the stream to conditions found in the unimpacted reference stream; for example, bacterial abundances and concentrations of some elements, such as sulfur, magnesium, and manganese, were different in the remediated stream than in the reference stream. BIO-ENV analysis revealed that changes in pH and iron concentration, associated with remediation, primarily explained temporal alterations in bacterial community structure. Although the sites sampled in the remediated stream were in relatively close proximity to each other, spatial variation in community composition suggests that differences in local environmental conditions may have large impacts on the microbial assemblage.

Prediction of acid mine drainage generation potential of various lithologies using static tests: Etili coal mine (NW Turkey) as a case study.

PubMed

Yucel, Deniz Sanliyuksel; Baba, Alper

2016-08-01

The Etili neighborhood in Can County (northwestern Turkey) has large reserves of coal and has been the site of many small- to medium-scale mining operations since the 1980s. Some of these have ceased working while others continue to operate. Once activities cease, the mining facilities and fields are usually abandoned without rehabilitation. The most significant environmental problem is acid mine drainage (AMD). This study was carried out to determine the acid generation potential of various lithological units in the Etili coal mine using static test methods. Seventeen samples were selected from areas with high acidic water concentrations: from different alteration zones belonging to volcanic rocks, from sedimentary rocks, and from coals and mine wastes. Static tests (paste pH, standard acid-base accounting, and net acid generation tests) were performed on these samples. The consistency of the static test results showed that oxidation of sulfide minerals, especially pyrite-which is widely found not only in the alteration zones of volcanic rocks but also in the coals and mine wastes-is the main factor controlling the generation of AMD in this mine. Lack of carbonate minerals in the region also increases the occurrence of AMD.

Mineralogical transformations controlling acid mine drainage chemistry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peretyazhko, Tetyana; Zachara, John M.; Boily, Jean F.

2009-05-30

The role of Fe(III) minerals in controlling acid mine drainage (AMD) chemistry was studied using samples from two AMD sites [Gum Boot (GB) and Fridays-2 (FR)] located in northern Pennsylvania. Chemical extractions, X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) were used to identify and characterize Fe(III) phases. The mineralogical analysis revealed that schwertmannite and goethite were the principal Fe(III) phases in the sediments. Schwertmannite transformation occurred at the GB site where poorly-crystallized goethite rich in surface-bound sulfate was initially formed. In contrast, no schwertmannite transformation occurred at the FR site. The goethite in GBmore » sediments had spherical morphology due to preservation of schwertmannite structure by adsorbed sulfate. Results of chemical extractions showed that poorly-crystallized goethite was subject to further crystallization accompanied by sulfate desorption. Changes in sulfate speciation preceded its desorption, with a conversion of bidentate- to monodentate-bound sulfate surface complexes. Laboratory sediment incubation experiments were conducted to evaluate the effect of mineral transformation on water chemistry. Incubation experiments were carried out with schwertmannite-containing sediments and AMD waters with different pH and chemical composition. The pH decreased to 1.9-2.2 in all suspensions and the concentrations of dissolved Fe and S increased significantly. Regardless of differences in the initial water composition, pH, Fe and S were similar in suspensions of the same sediment. XRD measurements revealed that schwertmannite transformed into goethite in GB and FR sediments during laboratory incubation. The incubation experiment demonstrated that schwertmannite transformation controlled AMD water chemistry during “closed system” laboratory contact.« less

Long term fluctuations of groundwater mine pollution in a sulfide mining district with dry Mediterranean climate: Implications for water resources management and remediation.

PubMed

Caraballo, Manuel A; Macías, Francisco; Nieto, José Miguel; Ayora, Carlos

2016-01-01

Water resources management and restoration strategies, and subsequently ecological and human life quality, are highly influenced by the presence of short and long term cycles affecting the intensity of a targeted pollution. On this respect, a typical acid mine drainage (AMD) groundwater from a sulfide mining district with dry Mediterranean climate (Iberian Pyrite Belt, SW Spain) was studied to unravel the effect of long term weather changes in water flow rate and metal pollutants concentration. Three well differentiated polluting stages were observed and the specific geochemical, mineralogical and hydrological processes involved (pyrite and enclosing rocks dissolution, evaporitic salts precipitation-redisolution and pluviometric long term fluctuations) were discussed. Evidencing the importance of including longer background monitoring stage in AMD management and restoration strategies, the present study strongly advise a minimum 5-years period of AMD continuous monitoring previous to the design of any AMD remediation system in regions with dry Mediterranean climate. Copyright © 2015 Elsevier B.V. All rights reserved.

Use of natural and applied tracers to guide targeted remediation efforts in an acid mine drainage system, Colorado Rockies, USA

USGS Publications Warehouse

Cowie, Rory; Williams, Mark W.; Wireman, Mike; Runkel, Robert L.

2014-01-01

Stream water quality in areas of the western United States continues to be degraded by acid mine drainage (AMD), a legacy of hard-rock mining. The Rico-Argentine Mine in southwestern Colorado consists of complex multiple-level mine workings connected to a drainage tunnel discharging AMD to passive treatment ponds that discharge to the Dolores River. The mine workings are excavated into the hillslope on either side of a tributary stream with workings passing directly under the stream channel. There is a need to define hydrologic connections between surface water, groundwater, and mine workings to understand the source of both water and contaminants in the drainage tunnel discharge. Source identification will allow targeted remediation strategies to be developed. To identify hydrologic connections we employed a combination of natural and applied tracers including isotopes, ionic tracers, and fluorescent dyes. Stable water isotopes (δ18O/δD) show a well-mixed hydrological system, while tritium levels in mine waters indicate a fast flow-through system with mean residence times of years not decades or longer. Addition of multiple independent tracers indicated that water is traveling through mine workings with minimal obstructions. The results from a simultaneous salt and dye tracer application demonstrated that both tracer types can be successfully used in acidic mine water conditions.

Compacted Sewage Sludge as a Barrier for Tailings: The Heavy Metal Speciation and Total Organic Carbon Content in the Compacted Sludge Specimen

PubMed Central

Zhang, Huyuan; Zhang, Qing; Yang, Bo; Wang, Jinfang

2014-01-01

Acid mine drainage (AMD) was the main environmental problem facing the mining industry. For AMD had high heavy metals content and low pH, the compacted sewage sludge might be a barrier for tailings whose oxidation and weathering produced AMD, with its own carbon source, microorganism reduction ability and impermeability. To study the heavy metals environmental risk, under the simulate AMD, the deionized water (DW), and the pH 2.1 sulfuric acid water (SA) seepage conditions, respectively, the changes of the chemical speciation of heavy metals Cd, Cu, Fe, Ni, Zn and total organic carbon (TOC) content in the compacted sewage sludge were assessed in the different periods. The results indicated according to the distribution of heavy metals, the potential mobility was for Cd: 6.08 under AMD, 7.48 under SA, ∞ under DW; for Cu: 0.08 under AMD, 0.17 under SA, 0.59 under DW; for Fe: 0.15 under AMD, 0.22 under SA, 0.22 under DW; for Ni: 2.60 under AMD, 1.69 under SA, 1.67 under DW; and for Zn: 0.15 under AMD, 0.23 under SA and 0.21 under DW at the second checking time. TOC content firstly decreased from 67.62±0% to 66.29±0.35%, then increased to 67.74±0.65% under the AMD seepage while TOC decreased to 63.30±0.53%, then to 61.33±0.37% under the DW seepage, decreased to 63.86±0.41%, then to 63.28±0.49% under SA seepage. That indicated under the AMD seepage, the suitable microorganisms communities in the compacted sewage sludge were activated. And the heavy metals environmental risk of compacted sewage sludge was lower with AMD condition than with other two. So the compacted sewage sludge as a barrier for tailings was feasible as the aspect of environmental risk assessment. PMID:24979755

[Microbial diversity and ammonia-oxidizing microorganism of a soil sample near an acid mine drainage lake].

PubMed

Liu, Ying; Wang, Li-Hua; Hao, Chun-Bo; Li, Lu; Li, Si-Yuan; Feng, Chuan-Ping

2014-06-01

The main physicochemical parameters of the soil sample which was collected near an acid mine drainage reservoir in Anhui province was analyzed. The microbial diversity and community structure was studied through the construction of bacteria and archaea 16S rRNA gene clone libraries and ammonia monooxygenase gene clone library of archaea. The functional groups which were responsible for the process of ammonia oxidation were also discussed. The results indicated that the soil sample had extreme low pH value (pH < 3) and high ions concentration, which was influenced by the acid mine drainage (AMD). All the 16S rRNA gene sequences of bacteria clone library fell into 11 phyla, and Acidobacteria played the most significant role in the ecosystem followed by Verrucomicrobia. A great number of acidophilic bacteria existed in the soil sample, such as Candidatus Koribacter versatilis and Holophaga sp.. The archaea clone library consisted of 2 phyla (Thaumarchaeota and Euryarchaeota). The abundance of Thaumarchaeota was remarkably higher than Euryarchaeota. The ammonia oxidation in the soil environment was probably driven by ammonia-oxidizing archaea, and new species of ammonia-oxidizing archaea existed in the soil sample.

Brook Trout Back in Aaron Run

EPA Pesticide Factsheets

Following a series of acid mine drainage (AMD) projects funded largely by EPA’s Clean Water Act Section 319 non-point source program, the pH level in Aaron Run is meeting Maryland’s water quality standard – and the brook trout are back.

Precipitation, pH and metal load in AMD river basins: an application of fuzzy clustering algorithms to the process characterization.

PubMed

Grande, J A; Andújar, J M; Aroba, J; de la Torre, M L; Beltrán, R

2005-04-01

In the present work, Acid Mine Drainage (AMD) processes in the Chorrito Stream, which flows into the Cobica River (Iberian Pyrite Belt, Southwest Spain) are characterized by means of clustering techniques based on fuzzy logic. Also, pH behavior in contrast to precipitation is clearly explained, proving that the influence of rainfall inputs on the acidity and, as a result, on the metal load of a riverbed undergoing AMD processes highly depends on the moment when it occurs. In general, the riverbed dynamic behavior is the response to the sum of instant stimuli produced by isolated rainfall, the seasonal memory depending on the moment of the target hydrological year and, finally, the own inertia of the river basin, as a result of an accumulation process caused by age-long mining activity.

Map of impact by acid mine drainage in the river network of The Iberian Pyrite Belt (Sw Spain).

PubMed

Grande, J A; Santisteban, M; de la Torre, M L; Dávila, J M; Pérez-Ostalé, E

2018-05-01

The Iberian Pyrite Belt (IPB), in the southwest of Europe, is characterized by high levels of contamination by acid mine drainage (AMD) in a large extent of its river network. In this scenario, it is necessary to characterize the degree of pollution of the mining leachates in the AMD-generating sources as well as of the main receiving watercourses. A map of impact of each basin was developed, based on the model proposed by Grande (2011) and the European Directive 98/83/EC that defines the quality standards for drinking water. The results indicate that practically all the mining leachates exceeded the maximum concentrations established by Directive 98/83/CE for Fe and Cd, almost 90% exceeded the limit for Mn and 82% for Al. Likewise, Fe, Cd, and Mn caused 'extremely high' degradation in most sampled leachates. Similarly, these metals, in addition to Pb, produced more pollution in watercourses located downstream of exploitations. Copyright © 2018 Elsevier Ltd. All rights reserved.

Membrane technology applied to acid mine drainage from copper mining.

PubMed

Ambiado, K; Bustos, C; Schwarz, A; Bórquez, R

2017-02-01

The objective of this study is to evaluate the treatment of high-strength acid mine drainage (AMD) from copper mining by nanofiltration (NF) and reverse osmosis (RO) at pilot scale. The performances of two commercial spiral-wound membranes - NF99 and RO98pHt, both from Alfa Laval - were compared. The effects of pressure and feed flow on ion rejection and permeate flux were evaluated. The results showed high ion removal under optimum pressure conditions, which reached 92% for the NF99 membrane and 98% for the RO98pHt membrane. Sulfate removal reached 97% and 99% for NF99 and RO98pHt, respectively. In the case of copper, aluminum, iron and manganese, the removal percentage surpassed 95% in both membranes. Although concentration polarization limited NF performance at higher pressures, permeate fluxes observed in NF were five times greater than those obtained by RO, with only slightly lower divalent ion rejection rates, making it a promising option for the treatment of AMD.

Geochemistry of rare earth elements in a passive treatment system built for acid mine drainage remediation.

PubMed

Prudêncio, Maria Isabel; Valente, Teresa; Marques, Rosa; Sequeira Braga, Maria Amália; Pamplona, Jorge

2015-11-01

Rare earth elements (REE) were used to assess attenuation processes in a passive system for acid mine drainage treatment (Jales, Portugal). Hydrochemical parameters and REE contents in water, soils and sediments were obtained along the treatment system, after summer and winter. A decrease of REE contents in the water resulting from the interaction with limestone after summer occurs; in the wetlands REE are significantly released by the soil particles to the water. After winter, a higher water dynamics favors the AMD treatment effectiveness and performance since REE contents decrease along the system; La and Ce are preferentially sequestered by ochre sludge but released to the water in the wetlands, influencing the REE pattern of the creek water. Thus, REE fractionation occurs in the passive treatment systems and can be used as tracer to follow up and understand the geochemical processes that promote the remediation of AMD. Copyright © 2015 Elsevier Ltd. All rights reserved.

Geochemical behavior of heavy metals in a Zn-Pb-Cu mining area in the State of Mexico (central Mexico).

PubMed

Lizárraga-Mendiola, L; González-Sandoval, M R; Durán-Domínguez, M C; Márquez-Herrera, C

2009-08-01

The geochemical behavior of zinc, lead and copper from sulfidic tailings in a mine site with potential to generate acidic drainage (pyrite (55%) and sphalerite (2%)) is reported in this paper. The mining area is divided in two zones, considering the topographic location of sampling points with respect to the tailings pile: (a) outer zone, out of the probable influence of acid mine drainage (AMD) pollution, and (b) inner zone, probably influenced by AMD pollution. Maximum total ions concentrations (mg/L) measured in superficial waters found were, in the outer zone: As (0.2), Cd (0.9), Fe (19), Mn (39), Pb (5.02), SO4(2-) (4650), Zn (107.67), and in the inner zone are As (0.1), Cd (0.2), Fe (88), Mn (13), Pb (6), SO4(2-) (4,880), Zn (46). The presence of these ions that exceeding the permissible maximum limits for human consume, could be associated to tailings mineralogy and acid leachates generated in tailings pile.

Organic substrates as electron donors in permeable reactive barriers for removal of heavy metals from acid mine drainage.

PubMed

Kijjanapanich, P; Pakdeerattanamint, K; Lens, P N L; Annachhatre, A P

2012-12-01

This research was conducted to select suitable natural organic substrates as potential carbon sources for use as electron donors for biological sulphate reduction in a permeable reactive barrier (PRB). A number of organic substrates were assessed through batch and continuous column experiments under anaerobic conditions with acid mine drainage (AMD) obtained from an abandoned lignite coal mine. To keep the heavy metal concentration at a constant level, the AMD was supplemented with heavy metals whenever necessary. Under anaerobic conditions, sulphate-reducing bacteria (SRB) converted sulphate into sulphide using the organic substrates as electron donors. The sulphide that was generated precipitated heavy metals as metal sulphides. Organic substrates, which yielded the highest sulphate reduction in batch tests, were selected for continuous column experiments which lasted over 200 days. A mixture of pig-farm wastewater treatment sludge, rice husk and coconut husk chips yielded the best heavy metal (Fe, Cu, Zn and Mn) removal efficiencies of over 90%.

Pilot-scale passive bioreactors for the treatment of acid mine drainage: efficiency of mushroom compost vs. mixed substrates for metal removal.

PubMed

Song, Hocheol; Yim, Gil-Jae; Ji, Sang-Woo; Neculita, Carmen Mihaela; Hwang, Taewoon

2012-11-30

Pilot-scale field-testing of passive bioreactors was performed to evaluate the efficiency of a mixture of four substrates (cow manure compost, mushroom compost, sawdust, and rice straw) relative to mushroom compost alone, and of the effect of the Fe/Mn ratio, during the treatment of acid mine drainage (AMD) over a 174-day period. Three 141 L columns, filled with either mushroom compost or the four substrate mixture (in duplicate), were set-up and fed with AMD from a closed mine site, in South Korea, using a 4-day hydraulic retention time. In the former bioreactor, effluent deterioration was observed over 1-2 months, despite the good efficiency predicted by the physicochemical characterization of mushroom compost. Steady state effluent quality was then noted for around 100 days before worsening in AMD source water occurred in response to seasonal variations in precipitation. Such changes in AMD quality resulted in performance deterioration in all reactors followed by a slow recovery toward the end of testing. Both substrates (mushroom compost and mixtures) gave satisfactory performance in neutralizing pH (6.1-7.8). Moreover, the system was able to consistently reduce sulfate from day 49, after the initial leaching out from organic substrates. Metal removal efficiencies were on the order of Al (∼100%) > Fe (68-92%) > Mn (49-61%). Overall, the mixed substrates showed comparable performance to mushroom compost, while yielding better effluent quality upon start-up. The results also indicated mushroom compost could release significant amounts of Mn and sulfate during bioreactor operation. Copyright © 2012 Elsevier Ltd. All rights reserved.

Characterization of limestone reacted with acid-mine drainage in a pulsed limestone bed treatment system at the Friendship Hill National Historical Site, Pennsylvania, USA

USGS Publications Warehouse

Hammarstrom, J.M.; Sibrell, P.L.; Belkin, H.E.

2003-01-01

Armoring of limestone is a common cause of failure in limestone-based acid-mine drainage (AMD) treatment systems. Limestone is the least expensive material available for acid neutralization, but is not typically recommended for highly acidic, Fe-rich waters due to armoring with Fe(III) oxyhydroxide coatings. A new AMD treatment technology that uses CO2 in a pulsed limestone bed reactor minimizes armor formation and enhances limestone reaction with AMD. Limestone was characterized before and after treatment with constant flow and with the new pulsed limestone bed process using AMD from an inactive coal mine in Pennsylvania (pH = 2.9, Fe = 150 mg/l, acidity = 1000 mg/l CaCO3). In constant flow experiments, limestone is completely armored with reddish-colored ochre within 48 h of contact in a fluidized bed reactor. Effluent pH initially increased from the inflow pH of 2.9 to over 7, but then decreased to 6 during operation. Limestone removed from a pulsed bed pilot plant is a mixture of unarmored, rounded and etched limestone grains and partially armored limestone and refractory mineral grains (dolomite, pyrite). The ???30% of the residual grains in the pulsed flow reactor that are armored have thicker (50- to 100-??m), more aluminous coatings and lack the gypsum rind that develops in the constant flow experiment. Aluminium-rich zones developed in the interior parts of armor rims in both the constant flow and pulsed limestone bed experiments in response to pH changes at the solid/solution interface. ?? 2003 Elsevier Ltd. All rights reserved.

Microbial stratification in low pH oxic and suboxic macroscopic growths along an acid mine drainage

PubMed Central

Méndez-García, Celia; Mesa, Victoria; Sprenger, Richard R; Richter, Michael; Diez, María Suárez; Solano, Jennifer; Bargiela, Rafael; Golyshina, Olga V; Manteca, Ángel; Ramos, Juan Luis; Gallego, José R; Llorente, Irene; Martins dos Santos, Vitor AP; Jensen, Ole N; Peláez, Ana I; Sánchez, Jesús; Ferrer, Manuel

2014-01-01

Macroscopic growths at geographically separated acid mine drainages (AMDs) exhibit distinct populations. Yet, local heterogeneities are poorly understood. To gain novel mechanistic insights into this, we used OMICs tools to profile microbial populations coexisting in a single pyrite gallery AMD (pH ∼2) in three distinct compartments: two from a stratified streamer (uppermost oxic and lowermost anoxic sediment-attached strata) and one from a submerged anoxic non-stratified mat biofilm. The communities colonising pyrite and those in the mature formations appear to be populated by the greatest diversity of bacteria and archaea (including ‘ARMAN' (archaeal Richmond Mine acidophilic nano-organisms)-related), as compared with the known AMD, with ∼44.9% unclassified sequences. We propose that the thick polymeric matrix may provide a safety shield against the prevailing extreme condition and also a massive carbon source, enabling non-typical acidophiles to develop more easily. Only 1 of 39 species were shared, suggesting a high metabolic heterogeneity in local microenvironments, defined by the O2 concentration, spatial location and biofilm architecture. The suboxic mats, compositionally most similar to each other, are more diverse and active for S, CO2, CH4, fatty acid and lipopolysaccharide metabolism. The oxic stratum of the streamer, displaying a higher diversity of the so-called ‘ARMAN'-related Euryarchaeota, shows a higher expression level of proteins involved in signal transduction, cell growth and N, H2, Fe, aromatic amino acids, sphingolipid and peptidoglycan metabolism. Our study is the first to highlight profound taxonomic and functional shifts in single AMD formations, as well as new microbial species and the importance of H2 in acidic suboxic macroscopic growths. PMID:24430486

Hydraulic retention time and pH affect the performance and microbial communities of passive bioreactors for treatment of acid mine drainage.

PubMed

Aoyagi, Tomo; Hamai, Takaya; Hori, Tomoyuki; Sato, Yuki; Kobayashi, Mikio; Sato, Yuya; Inaba, Tomohiro; Ogata, Atsushi; Habe, Hiroshi; Sakata, Takeshi

2017-12-01

For acceleration of removing toxic metals from acid mine drainage (AMD), the effects of hydraulic retention time (HRT) and pH on the reactor performance and microbial community structure in the depth direction of a laboratory-scale packed-bed bioreactor containing rice bran as waste organic material were investigated. The HRT was shortened stepwise from 25 to 12 h, 8 h, and 6 to 5 h under the neutral condition using AMD neutralized with limestone (pH 6.3), and from 25 to 20 h, 12 h, and 8 to 7 h under the acid condition using AMD (pH 3.0). Under the neutral condition, the bioreactor stably operated up to 6 h HRT, which was shorter than under the acid condition (up to 20 h HRT). During stable sulfate reduction, both the organic matter-remaining condition and the low oxidation-reduction potential condition in lower parts of the reactor were observed. Principal coordinate analysis of Illumina sequencing data of 16S rRNA genes revealed a dynamic transition of the microbial communities at the boundary between stable and unstable operation in response to reductions in HRT. During stable operation under both the neutral and acid conditions, several fermentative operational taxonomic units (OTUs) from the phyla Firmicutes and Bacteroidetes dominated in lower parts of the bioreactor, suggesting that co-existence of these OTUs might lead to metabolic activation of sulfate-reducing bacteria. In contrast, during unstable operation at shorter HRTs, an OTU from the candidate phylum OP11 were found under both conditions. This study demonstrated that these microorganisms can be used to monitor the treatment of AMD, which suggests stable or deteriorated performance of the system.

Remediation of AMD using industrial waste adsorbents

NASA Astrophysics Data System (ADS)

Mohammed, Nuur Hani Bte; Yaacob, Wan Zuhairi Wan

2016-11-01

The study investigates the characteristic of industrial waste as adsorbents and its potential as heavy metals absorbents in AMD samples. The AMD sample was collected from active mine pond and the pH was measured in situ. The metal contents were analyzed by ICP-MS. The AMD water was very acidic (pH< 3.5), and the average heavy metals content in AMD were high especially in Fe (822.029 mg/l). Fly ash was found to be the most effective absorbent material containing high percentage of CaO (57.24%) and SiO2 (13.88%), followed by ladle furnace slag containing of high amount of CaO (51.52%) and Al2O3 (21.23%), while biomass ash consists of SiO2 (43.07%) and CaO (12.97%). Tank analysis display a huge changes due to pH value change from acidity to nearly neutral phases. After 50 days, fly ash remediation successfully increase the AMD pH values from pH 2.57-7.09, while slag change from acidity to nearly alkaline phase from pH 2.60-7.3 and biomass has change to pH 2.54-6.8. Fly ash has successfully remove Fe, Mn, Cu, and Ni. Meanwhile, slag sample displays as an effective adsorbent to adsorb more Pb and Cd in acid mine drainage.

GEOCHEMICAL AND BIOLOGICAL ASPECTS OF SULFIDE MINERAL DISSOLUTION: LESSONS FROM IRON MOUNTAIN, CALIFORNIA. (R826189)

EPA Science Inventory

Abstract

The oxidative dissolution of sulfide minerals leading to acid mine drainage (AMD) involves a complex interplay between microorganisms, solutions, and mineral surfaces. Consequently, models that link molecular level reactions and the microbial communities that ...

THE EPA/DOE MINE WASTE TECHNOLOGY PROGRAM

EPA Science Inventory

Mining activities in the US (not counting coal) produce between 1-2B tons of mine waste annually. Since many of the ore mines involve sulfide minerals, the production of acid mine drainage (AMD) is a common problem from these abandoned mine sites. The combination of acidity, heav...

MINE WASTE TECHNOLOGY PROGRAM - SULFATE REDUCING BACTERIA REACTIVE WALL DEMO

EPA Science Inventory

Efforts reported in this document focused on the demonstration of a passive technology that could be used for remediation of
thousands of abandoned mines existing in the Western United States that emanate acid mine drainage (AMD). This passive remedial technology takes ad...

Inhibition of acid mine drainage and immobilization of heavy metals from copper flotation tailings using a marble cutting waste

NASA Astrophysics Data System (ADS)

Tozsin, Gulsen

2016-01-01

Acid mine drainage (AMD) with high concentrations of sulfates and metals is generated by the oxidation of sulfide bearing wastes. CaCO3-rich marble cutting waste is a residual material produced by the cutting and polishing of marble stone. In this study, the feasibility of using the marble cutting waste as an acid-neutralizing agent to inhibit AMD and immobilize heavy metals from copper flotation tailings (sulfide- bearing wastes) was investigated. Continuous-stirring shake-flask tests were conducted for 40 d, and the pH value, sulfate content, and dissolved metal content of the leachate were analyzed every 10 d to determine the effectiveness of the marble cutting waste as an acid neutralizer. For comparison, CaCO3 was also used as a neutralizing agent. The average pH value of the leachate was 2.1 at the beginning of the experiment ( t = 0). In the experiment employing the marble cutting waste, the pH value of the leachate changed from 6.5 to 7.8, and the sulfate and iron concentrations decreased from 4558 to 838 mg/L and from 536 to 0.01 mg/L, respectively, after 40 d. The marble cutting waste also removed more than 80wt% of heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn) from AMD generated by copper flotation tailings.

Removal of arsenic from synthetic acid mine drainage by electrochemical pH adjustment and coprecipitation with iron hydroxide.

PubMed

Wang, Jenny Weijun; Bejan, Dorin; Bunce, Nigel J

2003-10-01

Acid mine drainage (AMD), which is caused by the biological oxidation of sulfidic materials, frequently contains arsenic in the form of arsenite, As(III), and/or arsenate, As(V), along with much higher concentrations of dissolved iron. The present work is directed toward the removal of arsenic from synthetic AMD by raising the pH of the solution by electrochemical reduction of H+ to elemental hydrogen and coprecipitation of arsenic with iron(III) hydroxide, following aeration of the catholyte. Electrolysis was carried out at constant current using two-compartment cells separated with a cation exchange membrane. Four different AMD model systems were studied: Fe(III)/As(V), Fe(III)/As(III), Fe(II)/As(V), and Fe(II)/As(III) with the initial concentrations for Fe(III) 260 mg/L, Fe(II) 300 mg/L, As(V), and As(III) 8 mg/L. Essentially quantitative removal of arsenic and iron was achieved in all four systems, and the results were independent of whether the pH was adjusted electrochemically or by the addition of NaOH. Current efficiencies were approximately 85% when the pH of the effluent was 4-7. Residual concentrations of arsenic were close to the drinking water standard proposed by the World Health Organization (10 microg/L), far below the mine waste effluent standard (500 microg/L).

Role of multiple substrates (spent mushroom compost, ochre, steel slag, and limestone) in passive remediation of metal-containing acid mine drainage.

PubMed

Molahid, Verma Loretta M; Mohd Kusin, Faradiella; Madzin, Zafira

2018-01-12

The potential of selected materials in treating metal-rich acid mine drainage (AMD) has been investigated in a series of batch experiment. The efficiencies of both single and mixed substrates under two conditions i.e. low- and high-concentration solutions containing heavy metals were evaluated. Synthetic metal-containing AMD was used in the experiments treated using spent mushroom compost (SMC), ochre, steel slag (SS), and limestone. Different ratios of treatment materials were incorporated in the substrate mix and were tested in an anoxic condition. In the batch test, physicochemical parameters (pH, redox potential, total dissolved solids, conductivity, and Ca concentration) and heavy metals (Fe, Mn, Pb, Zn, and Al) were analysed. The mixed substrates have shown satisfactory performance in increasing pH with increasing Ca concentration and removing metals. It has been found that SS and ochre played an important role in the treatment of AMD. The results showed that the mixed substrates SM1 (i.e. 10% SMC mixed with 20% ochre, 30% steel slag, and 40% limestone) and SM2 (i.e. 20% SMC mixed with 30% ochre, 40% steel slag, and 10% limestone) were effective in increasing the pH from as low as 3.5-8.09, and removing heavy metals with more than 90% removal efficiencies.

Isolation and identification of a Candida digboiensis strain from an extreme acid mine drainage of the Lignite Mine, Gujarat.

PubMed

Patel, Mitesh J; Tipre, Devayani R; Dave, Shailesh R

2009-12-01

An extremely acidic mine drainage (AMD) water sample was collected in 1998 and 2008 from Panandhro lignite mine, Gujarat, India. The yeast isolated from this sample was identified using mini API identification system, as a member of genus Candida. The major cellular fatty acids detected by FAME from the isolate are C(16:0) and C(18:2) (cis 9,12)/C(18:0alpha) as 25.23 and 19.5%, respectively. The isolate was identified as Candida digboiensis by 18S rRNA gene sequence analysis and designated as Candida digboiensis SRDyeast1. Phylogenetic analysis using D1/D2 variable domains showed that the closest relative of this strain is Candida blankii with 3% divergence. This organism has been reported for the first time from the lignite mine AMD sample, and for cellular fatty acid analysis. This yeast is able to survive in the AMD sample preserved at 10-42 degrees C temperature since last 10 years along with iron oxidizing microorganisms. It can grow in the presence of 40% glucose, 10% NaCl and in the pH range of 1 to 10. The isolate is capable of producing enzymes like protease and lipase. This isolate differs from the type strain Candida digboiensis in as many as six physiological and metabolic characteristics.

A geochemical approach to the restoration plans for the Odiel River basin (SW Spain), a watershed deeply polluted by acid mine drainage.

PubMed

Macías, Francisco; Pérez-López, Rafael; Caraballo, Manuel A; Sarmiento, Aguasanta M; Cánovas, Carlos R; Nieto, Jose M; Olías, Manuel; Ayora, Carlos

2017-02-01

The Odiel River Basin (SW Spain) drains the central part of the Iberian Pyrite Belt (IPB), a world-class example of sulfide mining district and concomitantly of acid mine drainage (AMD) pollution. The severe AMD pollution and the incipient state of remediation strategies implemented in this region, coupled with the proximity of the deadline for compliance with the European Water Framework Directive (WFD), urge to develop a restoration and water resources management strategy. Furthermore, despite the presence of some reservoirs with acid waters in the Odiel basin, the construction of the Alcolea water reservoir has already started. On the basis of the positive results obtained after more than 10 years of developing a specific passive remediation technology (dispersed alkaline substrate (DAS)) for the highly polluted AMD of this region, a restoration strategy is proposed. The implementation of 13 DAS treatment plants in selected acid discharges along the Odiel and Oraque sub-basins and other restoration measurements of two acidic creeks is proposed as essential to obtain a good water quality in the future Alcolea reservoir. This restoration strategy is also suggested as an economically and environmentally sustainable approach to the extreme metal pollution affecting the waters of the region and could be considered the starting point for the future compliance with the WFD in the Odiel River Basin.

Effects of acid mine drainage from an abandoned copper mine, Britannia Mines, Howe Sound, British Columbia, Canada, on transplanted blue mussels (Mytilus edulis).

PubMed

Grout, J A; Levings, C D

2001-04-01

Juvenile mussels (Mytilus edulis) were transplanted to Howe Sound, British Columbia, Canada, along an apparent pollution gradient of acid mine drainage (AMD) from an abandoned copper (Cu) mine. Cages containing 75 mussels each were placed at a total of 15 stations and were exposed to concentrations of dissolved Cu in surface waters ranging from 5 to 1009 micrograms/l for a period of 41 days. Mussels located at stations closer to the source of AMD at the mouth of Britannia Creek bioaccumulated higher concentrations of Cu and zinc (Zn) in their tissues. Mussel growth was adversely affected by Cu tissue concentrations above 20 micrograms/g dry wt., while declines in survival and condition index occurred in mussels that bioaccumulated greater than 40 micrograms/g dry wt. Cu. Tissue Zn concentrations (117-192 micrograms/g dry wt.) were likely not high enough to have a direct impact on mussel health. Reduced survival of transplanted mussels was supported by an absence of natural mussels in contaminated areas. Phytoplankton was also severely reduced in areas contaminated by mine waters. Based on the weight of evidence, AMD from the Britannia mine had a deleterious impact on mussel survival in a zone extending at least 2.1 km to the north and 1.7 km to the south of Britannia Creek on the east shore of Howe Sound.

Arsenic Scavenging by Al-Substituted Ferrihydrites in a Circumneutral pH River Impacted by the Acid Mine Drainage of Carnoulès, Gard, France

NASA Astrophysics Data System (ADS)

ADRA, A.; Morin, G.; ona-Nguema, G.; Maillot, F.; Casiot, C.; Bruneel, O.

2013-12-01

Ferrihydrite (Fh) is a nanocrystalline ferric oxyhydroxide involved in the retention of pollutants in natural systems and in water-treatment processes. The status and properties of major chemical impurities in natural Fh is however still scarcely documented. Here we investigated the structure and reactivity of aluminum-rich Fh from river-bed sediments collected in a circumneutral river (pH 6-7) impacted by an arsenic-rich acid mine drainage (AMD). Extended X-ray absorption fine structure (EXAFS) spectroscopy at the Fe K-edge shows that Fh is the predominant mineral phase forming after neutralization of the AMD, in association with minor amount of schwertmannite transported from the AMD. EXAFS analysis indicates that Al(III) substitutes for Fe(III) ions into the Fh structure in the natural sediment samples, with local aluminum concentration within the 20-37×7 mol%Al range, in agreement with bulk chemical compositions. Synthetic aluminous Fh analogues prepared in the present study are found to be less Al-substituted (14-18×4 mol%Al). Finally, EXAFS analysis at the arsenic K-edge indicates that As(V) form similar inner-sphere surface complexes on the natural and synthetic Al-substituted Fh studied. Our results provide direct evidences for the scavenging of arsenic by natural Al- Fh, with possible implications for other pollutants in natural or engineered systems.

DEMONSTRATION OF AQUAFIX AND SAPS PASSIVE MINE WATER TREATMENT TECHNOLOGIES AT SUMMITVILLE MINE SITE, INNOVATIVE TECHNOLOGY EVALUATION REPORT

EPA Science Inventory

As part of the Superfund Innovative Technology Evaluation (SITE) Program, the U.S. Environmental Protection Agency evaluated two passive water treatment (PWT) technologies for metals removal from acid mine drainage (AMD) at the Summitville Mine Superfund Site in southern Colorado...

U.S. ARMY CORPS OF ENGINEERS ABANDONED MINE LAND REMEDIATION WORKSHOP

EPA Science Inventory

Mining activities in the US (not counting coal) produce 1-2 billion tons of mine waste annually. Since many of the ore mines involve sulfide minerals, the production of acid mine drainage (AMD) is a common problem from these abandoned mine sites. The combination of acidity, heavy...

ASSESSING AND MANAGING MERCURY FROM HISTORIC AND CURRENT MINING ACTIVITIES

EPA Science Inventory

Mining activities in the US (not counting coal) produce between one and two billion tons of mine waste annually. Since many of the ore mines involve sulfide minerals, the production of acid mine drainage (AMD) is a common problem from these abandoned mine sites. The combination o...

Sulfide oxidation and acid mine drainage formation within two active tailings impoundments in the Golden Quadrangle of the Apuseni Mountains, Romania.

PubMed

Sima, Mihaela; Dold, Bernhard; Frei, Linda; Senila, Marin; Balteanu, Dan; Zobrist, Jurg

2011-05-30

Sulfidic mine tailings have to be classified as one of the major source of hazardous materials leading to water contamination. This study highlights the processes leading to sulfide oxidation and acid mine drainage (AMD) formation in the active stage of two tailings impoundments located in the southern part of the Apuseni Mountains, in Romania, a well-known region for its long-term gold-silver and metal mining activity. Sampling was undertaken when both impoundments were still in operation in order to assess their actual stage of oxidation and long-term behavior in terms of the potential for acid mine drainage generation. Both tailings have high potential for AMD formation (2.5 and 3.7 wt.% of pyrite equivalent, respectively) with lesser amount of carbonates (5.6 and 3.6 wt.% of calcite equivalent) as neutralization potential (ABA=-55.6 and -85.1 tCaCO(3)/1000 t ) and showed clear signs of sulfide oxidation yet during operation. Sequential extraction results indicate a stronger enrichment and mobility of elements in the oxidized tailings: Fe as Fe(III) oxy-hydroxides and oxides (transformation from sulfide minerals, leaching in oxidation zone), Ca mainly in water soluble and exchangeable form where gypsum and calcite are dissolved and higher mobility of Cu for Ribita and Pb for Mialu. Two processes leading to the formation of mine drainage at this stage could be highlighted (1) a neutral Fe(II) plume forming in the impoundment with ferrihydrite precipitation at its outcrop and (2) acid mine drainage seeping in the unsaturated zone of the active dam, leading to the formation of schwertmannite at its outcrop. Copyright © 2011 Elsevier B.V. All rights reserved.

Effectiveness of the addition of alkaline materials at surface coal mines in preventing or abating acid mine drainage--Part 2. Mine site case studies

USGS Publications Warehouse

Brady, Keith; Smith, Michael W.; Beam, Richard L.; Cravotta,, Charles A.

1990-01-01

The effectiveness of preventing or ameliorating acid mine drainage (AMD) through the application of alkaline additives is evaluated for eight surface coal mines in Pennsylvania. Many of the mine sites had overburden characteristics that made prediction of post‐mining water quality uncertain. Alkaline materials were applied at rates ranging from 42 to greater than 1,000 tons as calcium carbonate per acre. In addition, two sites that were mined and reclaimed without alkaline additives are included for comparative purposes. Overburden sulfur concentration and "neutralization potential" (NP) data for multiple strata at each mine site were used to compute the cumulative, mass‐weighted "maximum potential acidity" (MPA) and "net neutralization potential" (NNP = NP ‐ MPA) by using three different calculation methods. Post‐reclamation water‐quality data were used to compute the net alkalinity (= alkalinity ‐ acidity). The most conservative determination of NNP, whereby MPA is calculated by multiplying the total sulfur concentration, in weight percent, by 62.5 instead of 31.25, yielded the best agreement with net alkalinity (patching signs on NNP and net alkalinity). The error in prediction using each method was that the reclaimed overburden was computed to be alkaline overall (NNP > 0), but the post‐reclamation water was acid (net alkalinity < 0). In general, alkaline addition rates were probably insufficient to neutralize, or too late to prevent, acid production in the mine spoil. At six of the seven mine sites that had overburden with insufficient NP relative to MPA (NNP < 0), the addition of alkaline materials failed to create alkaline mine drainage; AMD was formed or persisted. A control site which also had insufficient alkaline material, but did not incorporate alkaline additives, generated severe AMD. Two sites that had substantial, natural alkaline overburden produced alkaline drainage. Although the addition rates appear to be inadequate, other factors, such as unequal distribution and exposure of the acid‐forming or neutralizing materials and hydrogeological variability, complicate the evaluation of relative effectiveness of using different alkaline materials and placement of the acid‐ or alkaline‐producing materials.

Development and Validation of an Acid Mine Drainage Treatment Process for Source Water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lane, Ann

Throughout Northern Appalachia and surrounding regions, hundreds of abandoned mine sites exist which frequently are the source of Acid Mine Drainage (AMD). AMD typically contains metal ions in solution with sulfate ions which have been leached from the mine. These large volumes of water, if treated to a minimum standard, may be of use in Hydraulic Fracturing (HF) or other industrial processes. This project’s focus is to evaluate an AMD water treatment technology for the purpose of providing treated AMD as an alternative source of water for HF operations. The HydroFlex™ technology allows the conversion of a previous environmental liabilitymore » into an asset while reducing stress on potable water sources. The technology achieves greater than 95% water recovery, while removing sulfate to concentrations below 100 mg/L and common metals (e.g., iron and aluminum) below 1 mg/L. The project is intended to demonstrate the capability of the process to provide AMD as alternative source water for HF operations. The second budget period of the project has been completed during which Battelle conducted two individual test campaigns in the field. The first test campaign demonstrated the ability of the HydroFlex system to remove sulfate to levels below 100 mg/L, meeting the requirements indicated by industry stakeholders for use of the treated AMD as source water. The second test campaign consisted of a series of focused confirmatory tests aimed at gathering additional data to refine the economic projections for the process. Throughout the project, regular communications were held with a group of project stakeholders to ensure alignment of the project objectives with industry requirements. Finally, the process byproduct generated by the HydroFlex process was evaluated for the treatment of produced water against commercial treatment chemicals. It was found that the process byproduct achieved similar results for produced water treatment as the chemicals currently in use. Further, the process byproduct demonstrated better settling characteristics in bench scale testing. The field testing conducted in the second project budget period demonstrated the ability of the HydroFlex technology to meet industry requirements for AMD water chemical composition so that it can be used as source water in HF activities. System and operational improvements were identified in an additional series of confirmatory tests to achieve competitive cost targets. Finally, the application of the HydroFlex process byproduct in produced water treatment was demonstrated, further supporting the commercial implementation of the technology. Overall, the project results demonstrate a path to the economic treatment of AMD to support its increased use as source water in HF, particularly in regions with limited local freshwater availability.« less

Geochemical characterization of acid mine lakes in northwest Turkey and their effect on the environment.

PubMed

Yucel, Deniz Sanliyuksel; Baba, Alper

2013-04-01

Mining activity generates a large quantity of mine waste. The potential hazard of mine waste depends on the host mineral. The tendency of mine waste to produce acid mine drainage (AMD) containing potentially toxic metals depends on the amounts of sulfide, carbonate minerals, and trace-element concentrations found in ore deposits. The acid mine process is one of the most significant environmental challenges and a major source of water pollution worldwide. AMD and its effects were studied in northwest Turkey where there are several sedimentary and hydrothermal mineral deposits that have been economically extracted. The study area is located in Can county of Canakkale province. Canakkale contains marine, lagoon, and lake sediments precipitated with volcanoclastics that occurred as a result of volcanism, which was active during various periods from the Upper Eocene to Plio-Quaternary. Can county is rich in coal with a total lignite reserve >100 million tons and contains numerous mines that were operated by private companies and later abandoned without any remediation. As a result, human intervention in the natural structure and topography has resulted in large open pits and deterioration in these areas. Abandoned open pit mines typically fill with water from runoff and groundwater discharge, producing artificial lakes. Acid drainage waters from these mines have resulted in the degradation of surface-water quality around Can County. The average pH and electrical conductivity of acid mine lakes (AMLs) in this study were found to be 3.03 and 3831.33 μS cm(-1), respectively. Total iron (Fe) and aluminum (Al) levels were also found to be high (329.77 and 360.67 mg L(-1), respectively). The results show that the concentration of most elements, such as Fe and Al in particular, exceed national and international water-quality standards.

Fungi Contribute Critical but Spatially Varying Roles in Nitrogen and Carbon Cycling in Acid Mine Drainage

PubMed Central

Mosier, Annika C.; Miller, Christopher S.; Frischkorn, Kyle R.; Ohm, Robin A.; Li, Zhou; LaButti, Kurt; Lapidus, Alla; Lipzen, Anna; Chen, Cindy; Johnson, Jenifer; Lindquist, Erika A.; Pan, Chongle; Hettich, Robert L.; Grigoriev, Igor V.; Singer, Steven W.; Banfield, Jillian F.

2016-01-01

The ecosystem roles of fungi have been extensively studied by targeting one organism and/or biological process at a time, but the full metabolic potential of fungi has rarely been captured in an environmental context. We hypothesized that fungal genome sequences could be assembled directly from the environment using metagenomics and that transcriptomics and proteomics could simultaneously reveal metabolic differentiation across habitats. We reconstructed the near-complete 27 Mbp genome of a filamentous fungus, Acidomyces richmondensis, and evaluated transcript and protein expression in floating and streamer biofilms from an acid mine drainage (AMD) system. A. richmondensis transcripts involved in denitrification and in the degradation of complex carbon sources (including cellulose) were up-regulated in floating biofilms, whereas central carbon metabolism and stress-related transcripts were significantly up-regulated in streamer biofilms. These findings suggest that the biofilm niches are distinguished by distinct carbon and nitrogen resource utilization, oxygen availability, and environmental challenges. An isolated A. richmondensis strain from this environment was used to validate the metagenomics-derived genome and confirm nitrous oxide production at pH 1. Overall, our analyses defined mechanisms of fungal adaptation and identified a functional shift related to different roles in carbon and nitrogen turnover for the same species of fungi growing in closely located but distinct biofilm niches. PMID:26973616

LAND REBORN: TOOLS FOR THE 21ST CENTURY/NATIONAL ASSOCIATION OF ABANDONED MINE LAND PROGRAMS

EPA Science Inventory

Mining activities in the US (not counting coal) produce 1-2 billion tons of mine waste annually. Since many of the ore mines involve sulfide minerals, the production of acid mine drainage (AMD) is a common problem from these abandoned mine sites. The combination of acidity, heavy...

CHALLENGES OF PASSIVE TREATMENT OF METAL MINE DRAINAGE IN THE IBERIAN PYRITE BELT (SOUTHERN SPAIN): PRELIMINARY STUDIES

EPA Science Inventory

AMD in the Iberian Pyrite Belt is a problem of global scale. Successful implementation of passive treatment systems could remediate at least part of this problem at reasonable costs. However, initial trials with ALD and RAPS based on gravel size limestone failed due to rapid loss...

Significance of Microbial Communities and Interactions in Safeguarding Reactive Mine Tailings by Ecological Engineering▿†

PubMed Central

N̆ancucheo, Ivan; Johnson, D. Barrie

2011-01-01

Pyritic mine tailings (mineral waste generated by metal mining) pose significant risk to the environment as point sources of acidic, metal-rich effluents (acid mine drainage [AMD]). While the accelerated oxidative dissolution of pyrite and other sulfide minerals in tailings by acidophilic chemolithotrophic prokaryotes has been widely reported, other acidophiles (heterotrophic bacteria that catalyze the dissimilatory reduction of iron and sulfur) can reverse the reactions involved in AMD genesis, and these have been implicated in the “natural attenuation” of mine waters. We have investigated whether by manipulating microbial communities in tailings (inoculating with iron- and sulfur-reducing acidophilic bacteria and phototrophic acidophilic microalgae) it is possible to mitigate the impact of the acid-generating and metal-mobilizing chemolithotrophic prokaryotes that are indigenous to tailing deposits. Sixty tailings mesocosms were set up, using five different microbial inoculation variants, and analyzed at regular intervals for changes in physicochemical and microbiological parameters for up to 1 year. Differences between treatment protocols were most apparent between tailings that had been inoculated with acidophilic algae in addition to aerobic and anaerobic heterotrophic bacteria and those that had been inoculated with only pyrite-oxidizing chemolithotrophs; these differences included higher pH values, lower redox potentials, and smaller concentrations of soluble copper and zinc. The results suggest that empirical ecological engineering of tailing lagoons to promote the growth and activities of iron- and sulfate-reducing bacteria could minimize their risk of AMD production and that the heterotrophic populations could be sustained by facilitating the growth of microalgae to provide continuous inputs of organic carbon. PMID:21965397

Arsenic scavenging by aluminum-substituted ferrihydrites in a circumneutral pH river impacted by acid mine drainage.

PubMed

Adra, Areej; Morin, Guillaume; Ona-Nguema, Georges; Menguy, Nicolas; Maillot, Fabien; Casiot, Corinne; Bruneel, Odile; Lebrun, Sophie; Juillot, Farid; Brest, Jessica

2013-11-19

Ferrihydrite (Fh) is a nanocrystalline ferric oxyhydroxide involved in the retention of pollutants in natural systems and in water-treatment processes. The status and properties of major chemical impurities in natural Fh is however still scarcely documented. Here we investigated the structure of aluminum-rich Fh, and their role in arsenic scavenging in river-bed sediments from a circumneutral river (pH 6-7) impacted by an arsenic-rich acid mine drainage (AMD). Extended X-ray absorption fine structure (EXAFS) spectroscopy at the Fe K-edge shows that Fh is the predominant mineral phase forming after neutralization of the AMD, in association with minor amount of schwertmannite transported from the AMD. TEM-EDXS elemental mapping and SEM-EDXS analyses combined with EXAFS analysis indicates that Al(3+) substitutes for Fe(3+) ions into the Fh structure in the natural sediment samples, with local aluminum concentration within the 25-30 ± 10 mol %Al range. Synthetic aluminous Fh prepared in the present study are found to be less Al-substituted (14-20 ± 5 mol %Al). Finally, EXAFS analysis at the arsenic K-edge indicates that As(V) form similar inner-sphere surface complexes on the natural and synthetic Al-substituted Fh studied. Our results provide direct evidence for the scavenging of arsenic by natural Al-Fh, which emphasize the possible implication of such material for scavenging pollutants in natural or engineered systems.

Optimization of the operation of packed bed bioreactor to improve the sulfate and metal removal from acid mine drainage.

PubMed

Dev, Subhabrata; Roy, Shantonu; Bhattacharya, Jayanta

2017-09-15

The present study discusses the potentiality of using anaerobic Packed Bed Bioreactor (PBR) for the treatment of acid mine drainage (AMD). The multiple process parameters such as pH, hydraulic retention time (HRT), concentration of marine waste extract (MWE), total organic carbon (TOC) and sulfate were optimized together using Taguchi design. The order of influence of the parameters towards biological sulfate reduction was found to be pH > MWE > sulfate > HRT > TOC. At optimized conditions (pH - 7, 20% (v/v) MWE, 1500 mg/L sulfate, 48 h HRT and 2300 mg/L TOC), 98.3% and 95% sulfate at a rate of 769.7 mg/L/d. and 732.1 mg/L/d. was removed from the AMD collected from coal and metal mine, respectively. Efficiency of metal removal (Fe, Cu, Zn, Mg and Ni) was in the range of 94-98%. The levels of contaminants in the treated effluent were below the minimum permissible limits of industrial discharge as proposed by Bureau of Indian Standards (IS 2490:1981). The present study establishes the optimized conditions for PBR operation to completely remove sulfate and metal removal from AMD at high rate. The study also creates the future scope to develop an efficient treatment process for sulfate and metal-rich mine wastewater in a large scale. Copyright © 2017 Elsevier Ltd. All rights reserved.

Silane-based coatings on the pyrite for remediation of acid mine drainage.

PubMed

Diao, Zenghui; Shi, Taihong; Wang, Shizhong; Huang, Xiongfei; Zhang, Tao; Tang, Yetao; Zhang, Xiaying; Qiu, Rongliang

2013-09-01

Acid mine drainage (AMD) resulting from the oxidation of pyrite and other metal sulfides has caused significant environmental problems, including acidification of rivers and streams as well as leaching of toxic metals. With the goal of controlling AMD at the source, we evaluated the potential of tetraethylorthosilicate (TEOS) and n-propyltrimethoxysilane (NPS) coatings to suppress pyrite oxidation. The release of total Fe and SO4(-2) from uncoated and coated pyrite in the presence of a chemical oxidizing agent (H2O2) or iron-oxidizing bacteria (Acidithiobacillus ferrooxidans) was measured. Results showed that TEOS- and NPS-based coatings reduced chemical oxidation of pyrite by as much as 59 and 96% (based on Fe release), respectively, while biological oxidation of pyrite was reduced by 69 and 95%, respectively. These results were attributed to the formation of a dense network of Fe-O-Si and Si-O-Si bonds on the pyrite surface that limited permeation of oxygen, water, and bacteria. Compared with results for TEOS-coated pyrite, higher pH and lower concentrations of total Fe and SO4(-2) were observed for oxidation of NPS-coated pyrite, which was attributed to its crack-free morphology and the presence of hydrophobic groups on the NPS-based coating surface. The silane-based NPS coating was shown to be highly effective in suppressing pyrite oxidation, making it a promising alternative for remediation of AMD at its source. Copyright © 2013 Elsevier Ltd. All rights reserved.

Bioavailability and toxicity of metals from a contaminated sediment by acid mine drainage: linking exposure-response relationships of the freshwater bivalve Corbicula fluminea to contaminated sediment.

PubMed

Sarmiento, Aguasanta M; Bonnail, Estefanía; Nieto, José Miguel; DelValls, Ángel

2016-11-01

Streams and rivers strongly affected by acid mine drainage (AMD) have legal vacuum in terms of assessing the water toxicity, since the use of conventional environmental quality biomarkers is not possible due to the absence of macroinvertebrate organisms. The Asian clam Corbicula fluminea has been widely used as a biomonitor of metal contamination by AMD in freshwater systems. However, these clams are considered an invasive species in Spain and the transplantation in the field study is not allowed by the Environmental Protection Agency. To evaluate the use of the freshwater bivalve C. fluminea as a potential biomonitor for sediments contaminated by AMD, the metal bioavailability and toxicity were investigated in laboratory by exposure of clams to polluted sediments for 14 days. The studied sediments were classified as slightly contaminated with As, Cr, and Ni; moderately contaminated with Co; considerably contaminated with Pb; and heavily contaminated with Cd, Zn, and specially Cu, being reported as very toxic to Microtox. On the fourth day of the exposure, the clams exhibited an increase in concentration of Ga, Ba, Sb, and Bi (more than 100 %), followed by Co, Ni, and Pb (more than 60 %). After the fourth day, a decrease in concentration was observed for almost all metals studied except Ni. An allometric function was used to determine the relationship between the increases in metal concentration in soft tissue and the increasing bioavailable metal concentrations in sediments.

Exploring the effects of acid mine drainage on diatom teratology using geometric morphometry.

PubMed

Olenici, Adriana; Blanco, Saúl; Borrego-Ramos, María; Momeu, Laura; Baciu, Călin

2017-10-01

Metal pollution of aquatic habitats is a major and persistent environmental problem. Acid mine drainage (AMD) affects lotic systems in numerous and interactive ways. In the present work, a mining area (Roșia Montană) was chosen as study site, and we focused on two aims: (i) to find the set of environmental predictors leading to the appearance of the abnormal diatom individuals in the study area and (ii) to assess the relationship between the degree of valve outline deformation and AMD-derived pollution. In this context, morphological differences between populations of Achnanthidium minutissimum and A. macrocephalum, including normal and abnormal individuals, were evidenced by means of valve shape analysis. Geometric morphometry managed to capture and discriminate normal and abnormal individuals. Multivariate analyses (NMDS, PLS) separated the four populations of the two species mentioned and revealed the main physico-chemical parameters that influenced valve deformation in this context, namely conductivity, Zn, and Cu. ANOSIM test evidenced the presence of statistically significant differences between normal and abnormal individuals within both chosen Achnanthidium taxa. In order to determine the relative contribution of each of the measured physico-chemical parameters in the observed valve outline deformations, a PLS was conducted, confirming the results of the NMDS. The presence of deformed individuals in the study area can be attributed to the fact that the diatom communities were strongly affected by AMD released from old mining works and waste rock deposits.

Stable Carbon Isotope Characterization of CO2 Loss in Acid Mine Drainage Impacted Stream Water: Observations from a Laboratory Experiment

NASA Astrophysics Data System (ADS)

Ali, H. N.; Atekwana, E. A.

2007-05-01

Water from an acid mine drainage spring, ground water from a mine tailings pile, stream water and tap water were acidified to simulate acid mine drainage (AMD) contamination. The objective was to determine how acidification of stream water by AMD affected DIC loss and carbon isotope fraction. Two 20 L HDP containers (reactors) containing samples from each source were left un-acidified and allowed to evolve under ambient conditions for several weeks in the laboratory and two others were acidified. Acidification was carried out progressively with sulfuric acid to pH <3. For acidified samples, one reactor was acidified open to the atmosphere and the other closed from contact with atmosphere and CO2(g) was collected under vacuum. The un-acidified samples did not show significant alkalinity and DIC loss, and the 13C of DIC was enriched with time. The acidified samples showed decrease in alkalinity and DIC and increase in the 13C of DIC and CO2(g) with progressive acidification. The enrichment of 13C of DIC for un-acidified samples was due to exchange with atmospheric CO2. On the other hand, the 13C enrichment in the acidified samples was due to fractionation during dehydration of HCO3- and diffusive loss of CO2(g) from the aqueous phase. The actual values measured depended on the amount of CO2 lost from the aqueous phase during acidification. Samples with greater CO2 loss (closed acidification) had greater 13C enrichment. Beyond the HCO3- titration end point, the δ13C of DIC and CO2(g) was similar and nearly constant. The result of this study suggests that AMD effects on DIC can be modeled as a first order kinetic reaction and the isotope enrichment modeled using Rayleigh distillation.

Acid Mine Drainage Passive Remediation: Potential Use of Alkaline Clay, Optimal Mixing Ratio and Long Term Impacts

NASA Astrophysics Data System (ADS)

Plaza, F.; Liang, X.; Wen, Y.; Perone, H.

2015-12-01

Acid mine drainage (AMD) is one of the most adverse environmental problems of the mine industry. Surface water and ground water affected by this pollution are characterized by their acidity and the high content of sulfates and heavy metals. In this study, alkaline clay, an industrial waste with a high pH, which is utilized in the alumina refining process, was used as the remediation material to inhibit pyrite oxidation. Through a series of batch and column experiments, complemented with field measurements and geochemical modeling, three important issues associated with this passive and auto sustainable acid mine drainage remediation method were investigated: 1) the potential use of alkaline clay as an AMD remediation material, 2) the adequate alkaline clay/coal refuse mixing ratio (AC/CR) to ensure pH values near to neutral conditions, and, 3) the prediction of long term impacts, in terms of the trends of the main parameters involved in this process such as pH, concentrations of sulfate, iron and other dissolved contaminants. Both field measurements and the samples used for the experiments came from a coal waste site located in Mather, Pennsylvania. Alkaline clay proved to be an effective remediation material for AMD. It was found that 10% AC/CR is an adequate mixing ratio (i.e. the upper limit), which has been also indicated by field measurements. The concentrations of some contaminants such as iron, manganese or sulfate are significantly reduced with the remediation approach, compared to those representative concentrations found in mine tailings. Moreover, results suggest a very reliable long-term stability of the remediation (i.e. neutral pH conditions are maintained), thus enhancing the generation of iron precipitates that could produce pyrite grain coating and hardpan (i.e. cemented layer) on the surface. These processes also made the amended layer less porous, thus increasing water retention and hindering oxygen diffusion.

A novel method of utilizing permeable reactive kiddle (PRK) for the remediation of acid mine drainage.

PubMed

Lee, Woo-Chun; Lee, Sang-Woo; Yun, Seong-Taek; Lee, Pyeong-Koo; Hwang, Yu Sik; Kim, Soon-Oh

2016-01-15

Numerous technologies have been developed and applied to remediate AMD, but each has specific drawbacks. To overcome the limitations of existing methods and improve their effectiveness, we propose a novel method utilizing permeable reactive kiddle (PRK). This manuscript explores the performance of the PRK method. In line with the concept of green technology, the PRK method recycles industrial waste, such as steel slag and waste cast iron. Our results demonstrate that the PRK method can be applied to remediate AMD under optimal operational conditions. Especially, this method allows for simple installation and cheap expenditure, compared with established technologies. Copyright © 2015 Elsevier B.V. All rights reserved.

Radon as a natural tracer for gas transport within uranium waste rock piles.

PubMed

Silva, N C; Chagas, E G L; Abreu, C B; Dias, D C S; Lopez, D; Guerreiro, E T Z; Alberti, H L C; Braz, M L; Branco, O; Fleming, P

2014-07-01

Acid mine drainage (AMD) has been identified as the main cause for outflow of acid water and radioactive/non-radioactive contaminants. AMD encompasses pyrites oxidation when water and oxygen are available. AMD was identified in uranium waste rock piles (WRPs) of Indústrias Nucleares do Brasil-Caldas facility (Brazilian uranium mine), resulting in high costs for water treatment. AMD reduction is the main challenge, and scientific investigation has been conducted to understand oxygen and water transportation within WRPs, where 222Rn is used as natural tracer for oxygen transportation. The study consists of soil radon gas mapping in the top layer of WRP4 using active soil gas pumping, radon adsorption in active charcoal and 222Rn determination using high-resolution gamma-ray spectrometry. A sampling network of 71 points was built where samples were collected at a depth of 40 cm. Soil radon gas concentration ranged from 33.7 to 1484.2 kBq m(-3) with mean concentration of 320.7±263.3 kBq m(-3). © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Stream water quality in coal mined areas of the lower Cheat River Basin, West Virginia and Pennsylvania, during low-flow conditions, July 1997

USGS Publications Warehouse

Williams, Donald R.; Clark, Mary E.; Brown, Juliane B.

1999-01-01

IntroductionThe Cheat River Basin is in the Allegheny Plateau and Allegheny Mountain Sections of the Appalachian Plateau Physiographic Province (Fenneman, 1946) and is almost entirely within the state of West Virginia. The Cheat River drains an area of 1,422 square miles in Randolph, Tucker, Preston, and Monongalia Counties in West Virginia and Fayette County in Pennsylvania. From its headwaters in Randolph County, W.Va., the Cheat River flows 157 miles north to the Pennsylvania state line, where it enters the Monongahela River. The Cheat River drainage comprises approximately 19 percent of the total Monongahela River Basin. The Cheat River and streams within the Cheat River Basin are characterized by steep gradients, rock channels, and high flow velocities that have created a thriving white-water rafting industry for the area. The headwaters of the Cheat River contain some of the most pristine and aesthetic streams in West Virginia. The attraction to the area, particularly the lower part of the Cheat River Basin (the lower 412 square miles of the basin), has been suppressed because of poor water quality. The economy of the Lower Cheat River Basin has been dominated by coal mining over many decades. As a result, many abandoned deep and surface mines discharge untreated acid mine drainage (AMD), which degrades water quality, into the Cheat River and many of its tributary streams. Approximately 60 regulated mine-related discharges (West Virginia Department of Environmental Protection, 1996) and 185 abandoned mine sites (U.S. Office of Surface Mining, 1998) discharge treated and untreated AMD into the Cheat River and its tributaries.The West Virginia Department of Environmental Protection (WVDEP) Office of Abandoned Mine Lands and Reclamation (AML&R) has recently completed several AMD reclamation projects throughout the Cheat River Basin that have collectively improved the mainstem water quality. The AML&R office is currently involved in acquiring grant funds and designing treatment facilities for several additional AMD sites that adversely affect the Cheat River and its tributaries. To obtain the baseline water-quality information necessary to evaluate instream treatment and alternative methods for remediating AMD and its effects, the U.S. Geological Survey (USGS), in cooperation with the WVDEP, collected stream water samples at 111 sites throughout the Lower Cheat River Basin during low-flow conditions from July 16-18, 1997. The data also will provide information on stream water quality in areas affected by AMD and thus would point to priority areas of focus, such as the sources of the AMD. This report presents the results of analyses of the samples collected in July 1997 and describes a process for ranking of stream water-quality degradation as a guide to water-resource managers considering AMD remediation activities.

Hydrogeochemical variables regionalization--applying cluster analysis for a seasonal evolution model from an estuarine system affected by AMD.

PubMed

Grande, J A; Carro, B; Borrego, J; de la Torre, M L; Valente, T; Santisteban, M

2013-04-15

This study describes the spatial evolution of the hydrogeochemical parameters which characterise a strongly affected estuary by Acid Mine Drainage (AMD). The studied estuarine system receives AMD from the Iberian Pyrite Belt (SW Spain) and, simultaneously, is affected by the presence of an industrial chemical complex. Water sampling was performed in the year of 2008, comprising four sampling campaigns, in order to represent seasonality. The results show how the estuary can be divided into three areas of different behaviour in response to hydrogeochemical variables concentrations that define each sampling stations: on one hand, an area dominated by tidal influence; in the opposite end there is a second area including the points located in the two rivers headwaters that are not influenced by seawater; finally there is the area that can be defined as mixing zone. These areas are moved along the hydrological year due to seasonal chemical variations. Copyright © 2013 Elsevier Ltd. All rights reserved.

Metals Fate And Transport Modelling In Streams And Watersheds: State Of The Science And USEPA Workshop Review

EPA Science Inventory

Metals pollution in surface waters from point and non-point sources (NPS) is a widespread problem in the United States and worldwide (Lofts et al., 2007; USEPA, 2007). In the western United States, metals associated with acid mine drainage (AMD) from hardrock mines in mou...

30 CFR 935.25 - Approval of Ohio abandoned mine land reclamation plan amendments.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Plan to provide for the reclamation of areas causing acid mine drainage AMD and to revise the project... 30 Mineral Resources 3 2014-07-01 2014-07-01 false Approval of Ohio abandoned mine land... STATE OHIO § 935.25 Approval of Ohio abandoned mine land reclamation plan amendments. The following is a...

30 CFR 935.25 - Approval of Ohio abandoned mine land reclamation plan amendments.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Plan to provide for the reclamation of areas causing acid mine drainage AMD and to revise the project... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Approval of Ohio abandoned mine land... STATE OHIO § 935.25 Approval of Ohio abandoned mine land reclamation plan amendments. The following is a...

30 CFR 935.25 - Approval of Ohio abandoned mine land reclamation plan amendments.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Plan to provide for the reclamation of areas causing acid mine drainage AMD and to revise the project... 30 Mineral Resources 3 2013-07-01 2013-07-01 false Approval of Ohio abandoned mine land... STATE OHIO § 935.25 Approval of Ohio abandoned mine land reclamation plan amendments. The following is a...

30 CFR 935.25 - Approval of Ohio abandoned mine land reclamation plan amendments.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Plan to provide for the reclamation of areas causing acid mine drainage AMD and to revise the project... 30 Mineral Resources 3 2012-07-01 2012-07-01 false Approval of Ohio abandoned mine land... STATE OHIO § 935.25 Approval of Ohio abandoned mine land reclamation plan amendments. The following is a...

Observed And Modeled Seasonal Trends In Dissolved And Particulate Cu, Fe, Mn, And Zn In A Mining-Impacted Stream

EPA Science Inventory

North Fork Clear Creek (NFCC) in Colorado, an acid-mine drainage (AMD) impacted stream, was chosen to examine the distribution of dissolved and particulate Cu, Fe, Mn, and Zn in the water column, with respect to seasonal hydrologic controls. NFCC is a high-gradient stream with d...

Prediction of AMD generation potential in mining waste piles, in the Sarcheshmeh porphyry copper deposit, Iran.

PubMed

Modabberi, Soroush; Alizadegan, Ali; Mirnejad, Hassan; Esmaeilzadeh, Esmat

2013-11-01

This study investigates the possibility of acid mine drainage (AMD) generation in active and derelict mine waste piles in Sarcheshmeh Copper Mine produced in several decades, using static tests including acid-base accounting (ABA) and net acid-generating pH (NAGpH). In this study, 51 composite samples were taken from 11 waste heaps, and static ABA and NAGpH tests were carried out on samples. While some piles are acid producing at present and AMD is discharging from the piles, most of them do not show any indication on their AMD potential, and they were investigated to define their acid-producing potential. The analysis of data indicates that eight waste piles are potentially acid generating with net neutralization potentials (NNPs) of -56.18 to -199.3, net acid generating of 2.19-3.31, and NPRs from 0.18 to 0.44. Other waste piles exhibited either a very low sulfur, high carbonate content or excess carbonate over sulfur; hence, they are not capable of acid production or they can be considered as weak acid producers. Consistency between results of ABA and NAGpH tests using a variety of classification criteria validates these tests as powerful means for preliminary evaluation of AMD/ARD possibilities in any mining district. It is also concluded that some of the piles with very negative NNPs are capable to produce AMD naturally, and they can be used in heap leaching process for economic recovery of trace amounts of metals without applying any biostimulation methods.

Impacts of detrital nano- and micro-scale particles (dNP) on contaminant dynamics in a coal mine AMD treatment system.

PubMed

Lefticariu, Liliana; Sutton, Stephen R; Bender, Kelly S; Lefticariu, Mihai; Pentrak, Martin; Stucki, Joseph W

2017-01-01

Pollutants in acid mine drainage (AMD) are usually sequestered in neoformed nano- and micro-scale particles (nNP) through precipitation, co-precipitation, and sorption. Subsequent biogeochemical processes may control nNP stability and thus long-term contaminant immobilization. Mineralogical, chemical, and microbiological data collected from sediments accumulated over a six-year period in a coal-mine AMD treatment system were used to identify the pathways of contaminant dynamics. We present evidence that detrital nano- and micron-scale particles (dNP), composed mostly of clay minerals originating from the partial weathering of coal-mine waste, mediated biogeochemical processes that catalyzed AMD contaminant (1) immobilization by facilitating heterogeneous nucleation and growth of nNP in oxic zones, and (2) remobilization by promoting phase transformation and reductive dissolution of nNP in anoxic zones. We found that dNP were relatively stable under acidic conditions and estimated a dNP content of ~0.1g/L in the influent AMD. In the AMD sediments, the initial nNP precipitates were schwertmannite and poorly crystalline goethite, which transformed to well-crystallized goethite, the primary nNP repository. Subsequent reductive dissolution of nNP resulted in the remobilization of up to 98% of S and 95% of Fe accompanied by the formation of a compact dNP layer. Effective treatment of pollutants could be enhanced by better understanding the complex, dynamic role dNP play in mediating biogeochemical processes and contaminant dynamics at coal-mine impacted sites. Copyright © 2016 Elsevier B.V. All rights reserved.

Reduction of jarosite by Shewanella oneidensis MR-1 and secondary mineralization

NASA Astrophysics Data System (ADS)

Bingjie, Ouyang; Xiancai, Lu; Huan, Liu; Juan, Li; Tingting, Zhu; Xiangyu, Zhu; Jianjun, Lu; Rucheng, Wang

2014-01-01

Jarosite is a common mineral in a variety of environments formed by the oxidation of iron sulfide normally accompanying with the generation of acid mine drainage (AMD) in mining areas or acid rock drainages (ARD) in many localities. Decomposition of jarosite by dissimilatory iron reducing bacteria (DIRB) influences the mobility of many heavy metals generally accommodated in natural jarosite. This study examined the anaerobic reduction of synthesized jarosite by Shewanella oneidensis strain MR-1, a typical facultative bacteria. The release of ferrous and ferric ion, as well as sulfate and potassium, in the inoculated experimental group lasting 80 days is much higher than that in abiotic control groups. The detection of bicarbonate and acetate in experimental solution further confirms the mechanism of microbial reduction of jarosite, in which lactate acts as the electron donor. The produced ferrous iron stimulates the subsequent secondary mineralization, leading to precipitation and transformation of various iron-containing minerals. Green rust and goethite are the intermediate minerals of the microbial reduction process under anoxic conditions, and the end products include magnetite and siderite. In aerobic environments, goethite, magnetite and siderite were also detected, but the contents were relatively lower. While in abiotic experiments, only goethite has been detected as a product. Thus, the microbial reduction and subsequent mineral transformation can remarkably influence the geochemical cycling of iron and sulfur in supergene environments, as well as the mobility of heavy metals commonly accommodated in jarosite.

Downflow limestone beds for treatment of net-acidic, oxic, iron-laden drainage from a flooded Anthracite Mine, Pennsylvania, USA: 1. Field evaluation

USGS Publications Warehouse

Cravotta, C.A.; Ward, S.J.

2008-01-01

Passive-treatment systems that route acidic mine drainage (AMD) through crushed limestone and/or organic-rich substrates have been used to remove the acidity and metals from various AMD sources, with a wide range of effects. This study evaluates treatment of net-acidic, oxic, iron-laden AMD with limestone alone, and with organic-rich compost layered with the limestone. In the fall of 2003, a treatment system consisting of two parallel, 500-m2 downflow cells followed by a 400-m2 aerobic settling pond and wetland was installed to neutralize the AMD from the Bell Mine, a large source of AMD and baseflow to the Schuylkill River in the Southern Anthracite Coalfield, in east-central Pennsylvania. Each downflow cell consisted of a lower substrate layer of 1,090 metric tons (t) of dolomitic limestone (60 wt% CaCO3) and an upper layer of 300 t of calcitic limestone (95 wt% CaCO3); one of the downflow cells also included a 0.3 m thick layer of mushroom compost over the limestone. AMD with pH of 3.5-4.3, dissolved oxygen of 6.6-9.9 mg/L, iron of 1.9-5.4 mg/L, and aluminum of 0.8-1.9 mg/L flooded each cell to a depth 0.65 m above the treatment substrates, percolated through the substrates to underlying, perforated outflow pipes, and then flowed through the aerobic pond and wetland before discharging to the Schuylkill River. Data on the flow rates and chemistry of the effluent for the treatment system indicated substantial neutralization by the calcitic limestone but only marginal effects from the dolomitic limestone or compost. Because of its higher transmissivity, the treatment cell containing only limestone neutralized greater quantities of acidity than the cell containing compost and limestone. On average, the treatment system removed 62% of the influent acidity, 47% of the dissolved iron, 34% of the dissolved aluminum, and 8% of the dissolved manganese. Prior to treatment of the Bell Discharge, the Schuylkill River immediately below its confluence with the discharge had pH as low as 4.1 and supported few, if any, fish. However, within the first year of treatment, the pH was maintained at values of 5.0 or greater and native brook trout were documented immediately below the treatment system, though not above. ?? 2008 Springer-Verlag.

Towards "Precision Mining" of wastewater: Selective recovery of Cu from acid mine drainage onto diatomite supported nanoscale zerovalent iron particles.

PubMed

Crane, R A; Sapsford, D J

2018-07-01

This paper introduces the concept of 'Precision Mining' of metals which can be defined as a process for the selective in situ uptake of a metal from a material or media, with subsequent retrieval and recovery of the target metal. In order to demonstrate this concept nanoscale zerovalent iron (nZVI) was loaded onto diatomaceous earth (DE) and tested for the selective uptake of Cu from acid mine drainage (AMD) and subsequent release. Batch experiments were conducted using the AMD and nZVI-DE at 4.0-16.0 g/L. Results demonstrate nZVI-DE as highly selective for Cu removal with >99% uptake recorded after 0.25 h when using nZVI-DE concentrations ≥12.0 g/L, despite appreciable concentrations of numerous other metals in the AMD, namely: Co, Ni, Mn and Zn. Cu uptake was maintained in excess of 4 and 24 h when using nZVI-DE concentrations of 12.0 and 16.0 g/L respectively. Near-total Cu release from the nZVI-DE was then recorded and attributed to the depletion of the nZVI component and the subsequent Eh, DO and pH recovery. This novel Cu uptake and release mechanism, once appropriately engineered, holds great promise as a novel 'Precision Mining' process for the rapid and selective Cu recovery from acidic wastewater, process effluents and leach liquors. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Exploration of diffuse and discrete sources of acid mine drainage to a headwater mountain stream in Colorado, USA

USGS Publications Warehouse

Johnston, Allison; Runkel, Robert L.; Navarre-Sitchler, Alexis; Singha, Kamini

2017-01-01

We investigated the impact of acid mine drainage (AMD) contamination from the Minnesota Mine, an inactive gold and silver mine, on Lion Creek, a headwater mountain stream near Empire, Colorado. The objective was to map the sources of AMD contamination, including discrete sources visible at the surface and diffuse inputs that were not readily apparent. This was achieved using geochemical sampling, in-stream and in-seep fluid electrical conductivity (EC) logging, and electrical resistivity imaging (ERI) of the subsurface. The low pH of the AMD-impacted water correlated to high fluid EC values that served as a target for the ERI. From ERI, we identified two likely sources of diffuse contamination entering the stream: (1) the subsurface extent of two seepage faces visible on the surface, and (2) rainfall runoff washing salts deposited on the streambank and in a tailings pile on the east bank of Lion Creek. Additionally, rainfall leaching through the tailings pile is a potential diffuse source of contamination if the subsurface beneath the tailings pile is hydraulically connected with the stream. In-stream fluid EC was lowest when stream discharge was highest in early summer and then increased throughout the summer as stream discharge decreased, indicating that the concentration of dissolved solids in the stream is largely controlled by mixing of groundwater and snowmelt. Total dissolved solids (TDS) load is greatest in early summer and displays a large diel signal. Identification of diffuse sources and variability in TDS load through time should allow for more targeted remediation options.

Fungi contribute critical but spatially varying roles in nitrogen and carbon cycling in acid mine drainage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mosier, Annika C.; Miller, Christopher S.; Frischkorn, Kyle R.

The ecosystem roles of fungi have been extensively studied by targeting one organism and/or biological process at a time, but the full metabolic potential of fungi has rarely been captured in an environmental context. We hypothesized that fungal genome sequences could be assembled directly from the environment using metagenomics and that transcriptomics and proteomics could simultaneously reveal metabolic differentiation across habitats. We reconstructed the near-complete 27 Mbp genome of a filamentous fungus, Acidomyces richmondensis, and evaluated transcript and protein expression in floating and streamer biofilms from an acid mine drainage (AMD) system. A. richmondensis transcripts involved in denitrification and inmore » the degradation of complex carbon sources (including cellulose) were up-regulated in floating biofilms, whereas central carbon metabolism and stress-related transcripts were significantly up-regulated in streamer biofilms. Finally, these findings suggest that the biofilm niches are distinguished by distinct carbon and nitrogen resource utilization, oxygen availability, and environmental challenges. An isolated A. richmondensis strain from this environment was used to validate the metagenomics-derived genome and confirm nitrous oxide production at pH 1. Overall, our analyses defined mechanisms of fungal adaptation and identified a functional shift related to different roles in carbon and nitrogen turnover for the same species of fungi growing in closely located but distinct biofilm niches.« less

Fungi contribute critical but spatially varying roles in nitrogen and carbon cycling in acid mine drainage

DOE PAGES

Mosier, Annika C.; Miller, Christopher S.; Frischkorn, Kyle R.; ...

2016-03-03

The ecosystem roles of fungi have been extensively studied by targeting one organism and/or biological process at a time, but the full metabolic potential of fungi has rarely been captured in an environmental context. We hypothesized that fungal genome sequences could be assembled directly from the environment using metagenomics and that transcriptomics and proteomics could simultaneously reveal metabolic differentiation across habitats. We reconstructed the near-complete 27 Mbp genome of a filamentous fungus, Acidomyces richmondensis, and evaluated transcript and protein expression in floating and streamer biofilms from an acid mine drainage (AMD) system. A. richmondensis transcripts involved in denitrification and inmore » the degradation of complex carbon sources (including cellulose) were up-regulated in floating biofilms, whereas central carbon metabolism and stress-related transcripts were significantly up-regulated in streamer biofilms. Finally, these findings suggest that the biofilm niches are distinguished by distinct carbon and nitrogen resource utilization, oxygen availability, and environmental challenges. An isolated A. richmondensis strain from this environment was used to validate the metagenomics-derived genome and confirm nitrous oxide production at pH 1. Overall, our analyses defined mechanisms of fungal adaptation and identified a functional shift related to different roles in carbon and nitrogen turnover for the same species of fungi growing in closely located but distinct biofilm niches.« less

Five-year performance monitoring of a high-density polyethylene (HDPE) cover system at a reclaimed mine waste rock pile in the Sydney Coalfield (Nova Scotia, Canada).

PubMed

Power, Christopher; Ramasamy, Murugan; MacAskill, Devin; Shea, Joseph; MacPhee, Joseph; Mayich, David; Baechler, Fred; Mkandawire, Martin

2017-12-01

Cover systems are commonly placed over waste rock piles (WRPs) to limit atmospheric water and oxygen ingress and control the generation and release of acid mine drainage (AMD) to the receiving environment. Although covers containing geomembranes such as high-density polyethylene (HDPE) exhibit the attributes to be highly effective, there are few, if any, published studies monitoring their performance at full-scale WRPs. In 2011, a HDPE cover was installed over the Scotchtown Summit WRP in Nova Scotia, Canada, and extensive field performance monitoring was conducted over the next five years. A range of parameters within the atmosphere, cover, waste rock, groundwater and surface water, were monitored and integrated into a comprehensive hydrogeochemical conceptual model to assess (i) atmospheric ingress to the waste rock, (ii) waste rock acidity and depletion and (iii) evolution of groundwater and surface water quality. Results demonstrate that the cover is effective and meeting site closure objectives. Depletion in oxygen influx resulted in slower sulphide oxidation and AMD generation, while a significant reduction in water influx (i.e. 512 to 50 mm/year) resulted in diminished AMD release. Consistent improvements in groundwater quality (decrease in sulphate and metals; increase in pH) beneath and downgradient of the WRP were observed. Protection and/or significant improvement in surface water quality was evident in all surrounding watercourses due to the improved groundwater plume and elimination of contaminated runoff over previously exposed waste rock. A variably saturated flow and contaminant transport model is currently being developed to predict long-term cover system performance.

Definition of redox and pH influence in the AMD mine system using a fuzzy qualitative tool (Iberian Pyrite Belt, SW Spain).

PubMed

de la Torre, M L; Grande, J A; Valente, T; Perez-Ostalé, E; Santisteban, M; Aroba, J; Ramos, I

2016-03-01

Poderosa Mine is an abandoned pyrite mine, located in the Iberian Pyrite Belt which pours its acid mine drainage (AMD) waters into the Odiel river (South-West Spain). This work focuses on establishing possible reasons for interdependence between the potential redox and pH, with the load of metals and sulfates, as well as a set of variables that define the physical chemistry of the water-conductivity, temperature, TDS, and dissolved oxygen-transported by a channel from Poderosa mine affected by acid mine drainage, through the use of techniques of artificial intelligence: fuzzy logic and data mining. The sampling campaign was carried out in May of 2012. There were a total of 16 sites, the first inside the tunnel and the last at the mouth of the river Odiel, with a distance of approximately 10 m between each pair of measuring stations. While the tools of classical statistics, which are widely used in this context, prove useful for defining proximity ratios between variables based on Pearson's correlations, in addition to making it easier to handle large volumes of data and producing easier-to-understand graphs, the use of fuzzy logic tools and data mining results in better definition of the variations produced by external stimuli on the set of variables. This tool is adaptable and can be extrapolated to any system polluted by acid mine drainage using simple, intuitive reasoning.

Removal of phosphorus using chemically modified lignocellulosic materials

Treesearch

James S. Han; N. Hur; B. Choi; Soo-Hong Min

2003-01-01

Heavy metals from an acid mine drainage (AMD) site were precipitated on the surface of juniper fiber. The modified fiber was tested in lab-scaled batch and column tests and in the field. Elemental analysis showed that soluble iron species deposited on the fiber act as an inorganic adsorbent for anions. Sorption capacity, determined by fitting results to a Langmuir...

Pilot test of pollution control and metal resource recovery for acid mine drainage.

PubMed

Yan, Bo; Mai, Ge; Chen, Tao; Lei, Chang; Xiao, Xianming

2015-01-01

The study was undertaken in order to recover the metal resources from acid mine drainage (AMD). A 300 m(3)/d continuous system was designed and fractional precipitation technology employed for the main metals Fe, Cu, Zn, and Mn recovery. The system was operated for six months using actual AMD in situ. The chemicals' input and also the retention time was optimized. Furthermore, the material balance was investigated. With the system, the heavy metals of the effluent after the Mn neutralization precipitation were below the threshold value of the Chinese integrated wastewater discharge limit. The precipitates generated contained 42%, 12%, 31%, and 18% for Fe, Cu, Zn, and Mn, respectively, and the recovery rates of Fe, Cu, Zn, and Mn were 82%, 79%, 83%, and 83%, respectively. The yield range of the precipitate had significant correlation with the influent metal content. Using the X-ray diffraction analysis, the refinement for Fe, Cu, and Zn could be achieved through the processes of roasting and floatation. Cost-benefit was also discussed; the benefit from the recycled metal was able to pay for the cost of chemical reagents used. Most important of all, through the use of this technology, the frustrating sludge problems were solved.

Characterization of water reservoirs affected by acid mine drainage: geochemical, mineralogical, and biological (diatoms) properties of the water.

PubMed

Valente, T; Rivera, M J; Almeida, S F P; Delgado, C; Gomes, P; Grande, J A; de la Torre, M L; Santisteban, M

2016-04-01

This work presents a combination of geochemical, mineralogical, and biological data obtained in water reservoirs located in one of the most paradigmatic mining regions, suffering from acid mine drainage (AMD) problems: the Iberian Pyrite Belt (IPB). Four water reservoirs located in the Spanish sector of the IBP, storing water for different purposes, were selected to achieve an environmental classification based on the effects of AMD: two mining dams (Gossan and Águas Ácidas), a reservoir for industrial use (Sancho), and one with water used for human supply (Andévalo). The results indicated that the four reservoirs are subject to the effect of metallic loads from polluted rivers, although with different levels: Águas Ácidas > Gossan > Sancho ≥ Andévalo. In accordance, epipsammic diatom communities have differences in the respective composition and dominant taxa. The dominant diatoms in each reservoir indicated acid water: Pinnularia acidophila and Pinnularia aljustrelica were found in the most acidic dams (Gossan and Águas Ácidas, with pH <3), Pinnularia subcapitata in Sancho (pH 2.48-5.82), and Eunotia exigua in Andévalo (pH 2.34-6.15).

Field rates for natural attenuation of arsenic in Tinto Santa Rosa acid mine drainage (SW Spain).

PubMed

Asta, Maria P; Ayora, Carlos; Acero, Patricia; Cama, Jordi

2010-05-15

Reactive transport modelling of the main processes related to the arsenic natural attenuation observed in the acid mine drainage (AMD) impacted stream of Tinto Santa Rosa (SW Spain) was performed. Despite the simplicity of the kinetic expressions used to deal with arsenic attenuation processes, the model reproduced successfully the major chemical trends observed along the acid discharge. Results indicated that the rate of ferrous iron oxidation was similar to the one obtained in earlier field studies in which microbial catalysis is reported to occur. With regard to the scaled arsenic oxidation rate, it is one order of magnitude faster than the values obtained under laboratory conditions suggesting the existence of a catalytic agent in the natural system. Schwertmannite precipitation rate, which was represented by a simple kinetic expression relying on Fe(III) and pH, was in the range calculated for other AMD impacted sites. Finally, the obtained distribution coefficients used for representing arsenic sorption onto Fe(III) precipitates were lower than those deduced from reported laboratory data. This discrepancy is attributed to a decrease in the schwertmannite arsenate sorption capacity as sulphate increases in the solution. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Sensitivity of the mayfly Adenophlebia auriculata (Ephemeroptera: Leptophlebiidae) to MgSO4 and Na2SO4

NASA Astrophysics Data System (ADS)

Vellemu, E. C.; Mensah, P. K.; Griffin, N. J.; Odume, O. N.

2017-08-01

Acid mine drainage (AMD) continues to deteriorate water quality in freshwater ecosystems. Sulphates, a major salt component in AMD, can exacerbate AMD effects in freshwater because salts are toxic to aquatic life in high concentrations. Sulphates are predominant in South African AMD impacted freshwater ecosystems. In this study, the sensitivity of nymphs of the mayfly Adenophlebia auriculata (Ephemeroptera: Leptophlebiidae) was investigated by exposing the organisms to magnesium sulphate (MgSO4) and sodium sulphate (Na2SO4) as models of mining salinisation in short-term (96 h) and long-term (240 h) in static system tests. Short-term and long-term lethal concentrations of each salt were estimated using regression analyses. The results indicated that A. auriculata was more sensitive to MgSO4 (LC50 = 3.81 g/L) than Na2SO4 (LC50 = 8.78 g/L) after short-term exposures. However, this species became sensitive to Na2SO4 (LC10 = 0.19 g/L) but tolerant to MgSO4 (LC10 = 0.35 g/L) after long-term exposures. These results suggest that the 0.25 g/L sulphate compliance limit for South Africa is inadequate to protect A. auriculata from Na2SO4 toxicity in the long-term, yet it overprotects this species from MgSO4 exposures in the short-term. The findings of this study are an important major step in understanding the ecological effects of AMD to aquatic life.

Incorporation of basic research and service components in a field environmental geochemistry course

NASA Astrophysics Data System (ADS)

Senko, J.

2015-12-01

"Application-based service learning" (ABSL) refers to an approach to formal course instruction that integrates service and research components into the course. An ABSL approach was employed in a field-based environmental chemistry course, whose goal was to evaluate and monitor the aqueous geochemistry of coal mine-derived acid mine drainage (AMD) in the Appalachia basin. In this course, students conducted literature reviews on the geochemistry and environmental impacts of AMD, participated in a field sampling campaign of several AMD treatment systems, and conducted chemical analyses of the samples that they retrieved. The remainder of the course was dedicated to "lab meetings," during which data was analyzed, conclusions were drawn from the data, and a manuscript was drafted that described the findings of the field analyses, and made recommendations regarding the performance of the AMD treatment systems. The service component of the course focused on socioeconomic impacts of coal mining and the Appalachian region, with the final manuscript distributed to AMD treatment practitioners and state regulatory agencies. A comparison of pre- and post-course questionnaires that included Likert scale questions revealed that students' attitudes toward basic research improved over the period or the course. Based on the questionnaires attitudes toward service diminished, but "open-ended" questionnaires indicated an improved attitude toward both research and service, with an emphasis on the benefits of research that serves the community. Ultimately, we hope to develop approaches to compare the effectiveness of ABSL-based across disciplines.

Design and Testing of a New Diatom-Based Index for Heavy Metal Pollution.

PubMed

Fernández, M R; Martín, G; Corzo, J; de la Linde, A; García, E; López, M; Sousa, M

2018-01-01

The Tinto and Odiel river basins (SW Spain) are known worldwide for their unique water characteristics. Such uniqueness is a consequence of their flow through the Iberian Pyrite Belt (an area rich in metal sulphides) and the mining activities in the basins. A process of sulphide oxidation occurs in this region, which acidifies the water and increases the amount of heavy metals in it. As a result, the rivers suffer the so-called "acid mine drainage" (AMD). Traditional biotic diatom-based indexes (IPS, IBD, EPI-D, etc.) do not take into account the pollution caused by AMD. The purpose of this paper is to develop a new diatom-based index which can serve as a useful and quick monitoring tool. Such tool must reflect the level of AMD while being user friendly. We present the development and validation of the ICM (Índice de Contaminación por Metales or Metal Pollution Index). ICM demonstrated to meet successfully the above criteria and, therefore, can assess water quality in the Tinto and Odiel Rivers. In addition, ICM was applied with satisfactory results in the Guadiamar River (SW Spain), which was subjected to AMD too. Thus, we propose to make use of it in any other basin with the same type of pollution.

Downflow limestone beds for treatment of net-acidic, oxic, iron-laden drainage from a flooded anthracite mine, Pennsylvania, USA: 2. Laboratory evaluation

USGS Publications Warehouse

Cravotta, C.A.; Ward, S.J.; Hammarstrom, J.M.

2008-01-01

Acidic mine drainage (AMD) containing elevated concentrations of dissolved iron and other metals can be neutralized to varying degrees by reactions with limestone in passive treatment systems. We evaluated the chemical and mineralogical characteristics and the effectiveness of calcitic and dolomitic limestone for the neutralization of net-acidic, oxic, iron-laden AMD from a flooded anthracite mine. The calcitic limestone, with CaCO3 and MgCO3 contents of 99.8 and <0.1 wt%, respectively, and the dolomitic limestone, with CaCO3 and MgCO3 contents of 60.3 and 40.2 wt%, were used to construct a downflow treatment system in 2003 at the Bell Mine, a large source of AMD and baseflow to the Schuylkill River in the Southern Anthracite Coalfield, in east-central Pennsylvania. In the winter of 2002-2003, laboratory neutralization-rate experiments evaluated the evolution of effluent quality during 2 weeks of continuous contact between AMD from the Bell Mine and the crushed calcitic or dolomitic limestone in closed, collapsible containers (cubitainers). The cubitainer tests showed that: (1) net-alkaline effluent could be achieved with detention times greater than 3 h, (2) effluent alkalinities and associated dissolution rates were equivalent for uncoated and Fe(OH)3-coated calcitic limestone, and (3) effluent alkalinities and associated dissolution rates for dolomitic limestone were about half those for calcitic limestone. The dissolution rate data for the cubitainer tests were used with data on the volume of effuent and surface area of limestone in the treatment system at the Bell Mine to evaluate the water-quality data for the first 1.5 years of operation of the treatment system. These rate models supported the interpretation of field results and indicated that treatment benefits were derived mainly from the dissolution of calcitic limestone, despite a greater quantity of dolomitic limestone within the treatment system. The dissolution-rate models were extrapolated on a decadal scale to indicate the expected decreases in the mass of limestone and associated alkalinities resulting from the long-term reaction of AMD with the treatment substrate. The models indicated the calcitic limestone would need to be replenished approaching the 5-year anniversary of treatment operations to maintain net-alkaline effluent quality. ?? 2008 Springer-Verlag.

Metabolic versatility of small archaea Micrarchaeota and Parvarchaeota

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Lin-Xing; Mendez-Garcia, Celia; Dombrowski, Nina

Small acidophilic archaea belonging to Micrarchaeota and Parvarchaeota phyla are known to physically interact with some Thermoplasmatales members in nature. However, due to a lack of cultivation and limited genomes on hand, their biodiversity, metabolisms, and physiologies remain largely unresolved. For this study, we obtained 39 genomes from acid mine drainage (AMD) and hot spring environments around the world. 16S rRNA gene based analyses revealed that Parvarchaeota were only detected in AMD and hot spring habitats, while Micrarchaeota were also detected in others including soil, peat, hypersaline mat, and freshwater, suggesting a considerable higher diversity and broader than expected habitatmore » distribution for this phylum. Despite their small genomes (0.64-1.08 Mb), these archaea may contribute to carbon and nitrogen cycling by degrading multiple saccharides and proteins, and produce ATP via aerobic respiration and fermentation. Additionally, we identified several syntenic genes with homology to those involved in iron oxidation in six Parvarchae ota genomes, suggesting their potential role in iron cycling. However, both phyla lack biosynthetic pathways for amino acids and nucleotides, suggesting that they likely scavenge these biomolecules from the environment and/or other community members. Moreover, low-oxygen enrichments in laboratory confirmed our speculation that both phyla are microaerobic/anaerobic, based on several specific genes identified in them. Furthermore, phylogenetic analyses provide insights into the close evolutionary history of energy related functionalities between both phyla with Thermoplasmatales. These results expand our understanding of these elusive archaea by revealing their involvement in carbon, nitrogen, and iron cycling, and suggest their potential interactions with Thermoplasmatales on genomic scale.« less

Metabolic versatility of small archaea Micrarchaeota and Parvarchaeota.

PubMed

Chen, Lin-Xing; Méndez-García, Celia; Dombrowski, Nina; Servín-Garcidueñas, Luis E; Eloe-Fadrosh, Emiley A; Fang, Bao-Zhu; Luo, Zhen-Hao; Tan, Sha; Zhi, Xiao-Yang; Hua, Zheng-Shuang; Martinez-Romero, Esperanza; Woyke, Tanja; Huang, Li-Nan; Sánchez, Jesús; Peláez, Ana Isabel; Ferrer, Manuel; Baker, Brett J; Shu, Wen-Sheng

2018-03-01

Small acidophilic archaea belonging to Micrarchaeota and Parvarchaeota phyla are known to physically interact with some Thermoplasmatales members in nature. However, due to a lack of cultivation and limited genomes on hand, their biodiversity, metabolisms, and physiologies remain largely unresolved. Here, we obtained 39 genomes from acid mine drainage (AMD) and hot spring environments around the world. 16S rRNA gene based analyses revealed that Parvarchaeota were only detected in AMD and hot spring habitats, while Micrarchaeota were also detected in others including soil, peat, hypersaline mat, and freshwater, suggesting a considerable higher diversity and broader than expected habitat distribution for this phylum. Despite their small genomes (0.64-1.08 Mb), these archaea may contribute to carbon and nitrogen cycling by degrading multiple saccharides and proteins, and produce ATP via aerobic respiration and fermentation. Additionally, we identified several syntenic genes with homology to those involved in iron oxidation in six Parvarchaeota genomes, suggesting their potential role in iron cycling. However, both phyla lack biosynthetic pathways for amino acids and nucleotides, suggesting that they likely scavenge these biomolecules from the environment and/or other community members. Moreover, low-oxygen enrichments in laboratory confirmed our speculation that both phyla are microaerobic/anaerobic, based on several specific genes identified in them. Furthermore, phylogenetic analyses provide insights into the close evolutionary history of energy related functionalities between both phyla with Thermoplasmatales. These results expand our understanding of these elusive archaea by revealing their involvement in carbon, nitrogen, and iron cycling, and suggest their potential interactions with Thermoplasmatales on genomic scale.

Metabolic versatility of small archaea Micrarchaeota and Parvarchaeota

DOE PAGES

Chen, Lin-Xing; Mendez-Garcia, Celia; Dombrowski, Nina; ...

2017-12-08

Small acidophilic archaea belonging to Micrarchaeota and Parvarchaeota phyla are known to physically interact with some Thermoplasmatales members in nature. However, due to a lack of cultivation and limited genomes on hand, their biodiversity, metabolisms, and physiologies remain largely unresolved. For this study, we obtained 39 genomes from acid mine drainage (AMD) and hot spring environments around the world. 16S rRNA gene based analyses revealed that Parvarchaeota were only detected in AMD and hot spring habitats, while Micrarchaeota were also detected in others including soil, peat, hypersaline mat, and freshwater, suggesting a considerable higher diversity and broader than expected habitatmore » distribution for this phylum. Despite their small genomes (0.64-1.08 Mb), these archaea may contribute to carbon and nitrogen cycling by degrading multiple saccharides and proteins, and produce ATP via aerobic respiration and fermentation. Additionally, we identified several syntenic genes with homology to those involved in iron oxidation in six Parvarchae ota genomes, suggesting their potential role in iron cycling. However, both phyla lack biosynthetic pathways for amino acids and nucleotides, suggesting that they likely scavenge these biomolecules from the environment and/or other community members. Moreover, low-oxygen enrichments in laboratory confirmed our speculation that both phyla are microaerobic/anaerobic, based on several specific genes identified in them. Furthermore, phylogenetic analyses provide insights into the close evolutionary history of energy related functionalities between both phyla with Thermoplasmatales. These results expand our understanding of these elusive archaea by revealing their involvement in carbon, nitrogen, and iron cycling, and suggest their potential interactions with Thermoplasmatales on genomic scale.« less

Binning of shallowly sampled metagenomic sequence fragments reveals that low abundance bacteria play important roles in sulfur cycling and degradation of complex organic polymers in an acid mine drainage community

NASA Astrophysics Data System (ADS)

Dick, G. J.; Andersson, A.; Banfield, J. F.

2007-12-01

Our understanding of environmental microbiology has been greatly enhanced by community genome sequencing of DNA recovered directly the environment. Community genomics provides insights into the diversity, community structure, metabolic function, and evolution of natural populations of uncultivated microbes, thereby revealing dynamics of how microorganisms interact with each other and their environment. Recent studies have demonstrated the potential for reconstructing near-complete genomes from natural environments while highlighting the challenges of analyzing community genomic sequence, especially from diverse environments. A major challenge of shotgun community genome sequencing is identification of DNA fragments from minor community members for which only low coverage of genomic sequence is present. We analyzed community genome sequence retrieved from biofilms in an acid mine drainage (AMD) system in the Richmond Mine at Iron Mountain, CA, with an emphasis on identification and assembly of DNA fragments from low-abundance community members. The Richmond mine hosts an extensive, relatively low diversity subterranean chemolithoautotrophic community that is sustained entirely by oxidative dissolution of pyrite. The activity of these microorganisms greatly accelerates the generation of AMD. Previous and ongoing work in our laboratory has focused on reconstrucing genomes of dominant community members, including several bacteria and archaea. We binned contigs from several samples (including one new sample and two that had been previously analyzed) by tetranucleotide frequency with clustering by Self-Organizing Maps (SOM). The binning, evaluated by comparison with information from the manually curated assembly of the dominant organisms, was found to be very effective: fragments were correctly assigned with 95% accuracy. Improperly assigned fragments often contained sequences that are either evolutionarily constrained (e.g. 16S rRNA genes) or mobile elements that are not expected to reflect the tetranucleotide frequency signature of the host genome. Four unknown tetranucleotide frequency clusters with significant sequence (6 Mb total) were noted and analyzed further. Based on phylogenetic markers and BLAST results, these clusters represent low abundance bacteria including Acintobacteria, Firmicutes, and Proteobacteria. Functional analysis of these clusters revealved that the low- abundance bacteria harbor genes that could potentially encode important ecosystem functions such as sulfur utilization (e.g. polysulfide reductase) and polymer degradation (e.g. chitinase and glycoside hydrolase). We conclude that ESOM clustering of tetranucleotide frequency patterns is an effective method for rapidly binning shotgun community genomic sequences and a valuable tool for analyzing minor community members, which despite their low abundance may play crucial ecological roles.

Comparison of environmental and isolate Sulfobacillus genomes reveals diverse carbon, sulfur, nitrogen, and hydrogen metabolisms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Justice, Nicholas B.; Norman, Anders; Brown, Christopher T.

Bacteria of the genus Sulfobacillus are found worldwide as members of microbial communities that accelerate sulfide mineral dissolution in acid mine drainage environments (AMD), acid-rock drainage environments (ARD), as well as in industrial bioleaching operations. Despite their frequent identification in these environments, their role in biogeochemical cycling is poorly understood. Here we report draft genomes of five species of the Sulfobacillus genus (AMDSBA1-5) reconstructed by cultivation-independent sequencing of biofilms sampled from the Richmond Mine (Iron Mountain, CA). Three of these species (AMDSBA2, AMDSBA3, and AMDSBA4) have no cultured representatives while AMDSBA1 is a strain of S. benefaciens, and AMDSBA5 amore » strain of S. thermosulfidooxidans. We analyzed the diversity of energy conservation and central carbon metabolisms for these genomes and previously published Sulfobacillus genomes. Pathways of sulfur oxidation vary considerably across the genus, including the number and type of subunits of putative heterodisulfide reductase complexes likely involved in sulfur oxidation. The number and type of nickel-iron hydrogenase proteins varied across the genus, as does the presence of different central carbon pathways. Only the AMDSBA3 genome encodes a dissimilatory nitrate reducatase and only the AMDSBA5 and S. thermosulfidooxidans genomes encode assimilatory nitrate reductases. Lastly, within the genus, AMDSBA4 is unusual in that its electron transport chain includes a cytochrome bc type complex, a unique cytochrome c oxidase, and two distinct succinate dehydrogenase complexes. Overall, the results significantly expand our understanding of carbon, sulfur, nitrogen, and hydrogen metabolism within the Sulfobacillus genus.« less

Comparison of environmental and isolate Sulfobacillus genomes reveals diverse carbon, sulfur, nitrogen, and hydrogen metabolisms

DOE PAGES

Justice, Nicholas B.; Norman, Anders; Brown, Christopher T.; ...

2014-12-15

Bacteria of the genus Sulfobacillus are found worldwide as members of microbial communities that accelerate sulfide mineral dissolution in acid mine drainage environments (AMD), acid-rock drainage environments (ARD), as well as in industrial bioleaching operations. Despite their frequent identification in these environments, their role in biogeochemical cycling is poorly understood. Here we report draft genomes of five species of the Sulfobacillus genus (AMDSBA1-5) reconstructed by cultivation-independent sequencing of biofilms sampled from the Richmond Mine (Iron Mountain, CA). Three of these species (AMDSBA2, AMDSBA3, and AMDSBA4) have no cultured representatives while AMDSBA1 is a strain of S. benefaciens, and AMDSBA5 amore » strain of S. thermosulfidooxidans. We analyzed the diversity of energy conservation and central carbon metabolisms for these genomes and previously published Sulfobacillus genomes. Pathways of sulfur oxidation vary considerably across the genus, including the number and type of subunits of putative heterodisulfide reductase complexes likely involved in sulfur oxidation. The number and type of nickel-iron hydrogenase proteins varied across the genus, as does the presence of different central carbon pathways. Only the AMDSBA3 genome encodes a dissimilatory nitrate reducatase and only the AMDSBA5 and S. thermosulfidooxidans genomes encode assimilatory nitrate reductases. Lastly, within the genus, AMDSBA4 is unusual in that its electron transport chain includes a cytochrome bc type complex, a unique cytochrome c oxidase, and two distinct succinate dehydrogenase complexes. Overall, the results significantly expand our understanding of carbon, sulfur, nitrogen, and hydrogen metabolism within the Sulfobacillus genus.« less

Monitoring of Soil Remediation Process in the Metal Mining Area

NASA Astrophysics Data System (ADS)

Kim, Kyoung-Woong; Ko, Myoung-Soo; Han, Hyeop-jo; Lee, Sang-Ho; Na, So-Young

2016-04-01

Stabilization using proper additives is an effective soil remediation technique to reduce As mobility in soil. Several researches have reported that Fe-containing materials such as amorphous Fe-oxides, goethite and hematite were effective in As immobilization and therefore acid mine drainage sludge (AMDS) may be potential material for As immobilization. The AMDS is the by-product from electrochemical treatment of acid mine drainage and mainly contains Fe-oxide. The Chungyang area in Korea is located in the vicinity of the huge abandoned Au-Ag Gubong mine which was closed in the 1970s. Large amounts of mine tailings have been remained without proper treatment and the mobilization of mine tailings can be manly occurred during the summer heavy rainfall season. Soil contamination from this mobilization may become an urgent issue because it can cause the contamination of groundwater and crop plants in sequence. In order to reduce the mobilization of the mine tailings, the pilot scale study of in-situ stabilization using AMDS was applied after the batch and column experiments in the lab. For the monitoring of stabilization process, we used to determine the As concentration in crop plants grown on the field site but it is not easily applicable because of time and cost. Therefore, we may need simple monitoring technique to measure the mobility or leachability which can be comparable with As concentration in crop plants. We compared several extraction methods to suggest the representative single extraction method for the monitoring of soil stabilization efficiency. Several selected extraction methods were examined and Mehlich 3 extraction method using the mixture of NH4F, EDTA, NH4NO3, CH3COOH and HNO3 was selected as the best predictor of the leachability or mobility of As in the soil remediation process.

Biosorption of metal and salt tolerant microbial isolates from a former uranium mining area. Their impact on changes in rare earth element patterns in acid mine drainage.

PubMed

Haferburg, Götz; Merten, Dirk; Büchel, Georg; Kothe, Erika

2007-12-01

The concentration of metals in microbial habitats influenced by mining operations can reach enormous values. Worldwide, much emphasis is placed on the research of resistance and biosorptive capacities of microorganisms suitable for bioremediation purposes. Using a collection of isolates from a former uranium mining area in Eastern Thuringia, Germany, this study presents three Gram-positive bacterial strains with distinct metal tolerances. These strains were identified as members of the genera Bacillus, Micrococcus and Streptomyces. Acid mine drainage (AMD) originating from the same mining area is characterized by high metal concentrations of a broad range of elements and a very low pH. AMD was analyzed and used as incubation solution. The sorption of rare earth elements (REE), aluminum, cobalt, copper, manganese, nickel, strontium, and uranium through selected strains was studied during a time course of four weeks. Biosorption was investigated after one hour, one week and four weeks by analyzing the concentrations of metals in supernatant and biomass. Additionally, dead biomass was investigated after four weeks of incubation. The maximum of metal removal was reached after one week. Up to 80% of both Al and Cu, and more than 60% of U was shown to be removed from the solution. High concentrations of metals could be bound to the biomass, as for example 2.2 mg/g U. The strains could survive four weeks of incubation. Distinct and different patterns of rare earth elements of the inoculated and non-inoculated AMD water were observed. Changes in REE patterns hint at different binding types of heavy metals regarding incubation time and metabolic activity of the cells. (c) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Predicting taxonomic and functional structure of microbial communities in acid mine drainage

PubMed Central

Kuang, Jialiang; Huang, Linan; He, Zhili; Chen, Linxing; Hua, Zhengshuang; Jia, Pu; Li, Shengjin; Liu, Jun; Li, Jintian; Zhou, Jizhong; Shu, Wensheng

2016-01-01

Predicting the dynamics of community composition and functional attributes responding to environmental changes is an essential goal in community ecology but remains a major challenge, particularly in microbial ecology. Here, by targeting a model system with low species richness, we explore the spatial distribution of taxonomic and functional structure of 40 acid mine drainage (AMD) microbial communities across Southeast China profiled by 16S ribosomal RNA pyrosequencing and a comprehensive microarray (GeoChip). Similar environmentally dependent patterns of dominant microbial lineages and key functional genes were observed regardless of the large-scale geographical isolation. Functional and phylogenetic β-diversities were significantly correlated, whereas functional metabolic potentials were strongly influenced by environmental conditions and community taxonomic structure. Using advanced modeling approaches based on artificial neural networks, we successfully predicted the taxonomic and functional dynamics with significantly higher prediction accuracies of metabolic potentials (average Bray–Curtis similarity 87.8) as compared with relative microbial abundances (similarity 66.8), implying that natural AMD microbial assemblages may be better predicted at the functional genes level rather than at taxonomic level. Furthermore, relative metabolic potentials of genes involved in many key ecological functions (for example, nitrogen and phosphate utilization, metals resistance and stress response) were extrapolated to increase under more acidic and metal-rich conditions, indicating a critical strategy of stress adaptation in these extraordinary communities. Collectively, our findings indicate that natural selection rather than geographic distance has a more crucial role in shaping the taxonomic and functional patterns of AMD microbial community that readily predicted by modeling methods and suggest that the model-based approach is essential to better understand natural acidophilic microbial communities. PMID:26943622

Predicting taxonomic and functional structure of microbial communities in acid mine drainage.

PubMed

Kuang, Jialiang; Huang, Linan; He, Zhili; Chen, Linxing; Hua, Zhengshuang; Jia, Pu; Li, Shengjin; Liu, Jun; Li, Jintian; Zhou, Jizhong; Shu, Wensheng

2016-06-01

Predicting the dynamics of community composition and functional attributes responding to environmental changes is an essential goal in community ecology but remains a major challenge, particularly in microbial ecology. Here, by targeting a model system with low species richness, we explore the spatial distribution of taxonomic and functional structure of 40 acid mine drainage (AMD) microbial communities across Southeast China profiled by 16S ribosomal RNA pyrosequencing and a comprehensive microarray (GeoChip). Similar environmentally dependent patterns of dominant microbial lineages and key functional genes were observed regardless of the large-scale geographical isolation. Functional and phylogenetic β-diversities were significantly correlated, whereas functional metabolic potentials were strongly influenced by environmental conditions and community taxonomic structure. Using advanced modeling approaches based on artificial neural networks, we successfully predicted the taxonomic and functional dynamics with significantly higher prediction accuracies of metabolic potentials (average Bray-Curtis similarity 87.8) as compared with relative microbial abundances (similarity 66.8), implying that natural AMD microbial assemblages may be better predicted at the functional genes level rather than at taxonomic level. Furthermore, relative metabolic potentials of genes involved in many key ecological functions (for example, nitrogen and phosphate utilization, metals resistance and stress response) were extrapolated to increase under more acidic and metal-rich conditions, indicating a critical strategy of stress adaptation in these extraordinary communities. Collectively, our findings indicate that natural selection rather than geographic distance has a more crucial role in shaping the taxonomic and functional patterns of AMD microbial community that readily predicted by modeling methods and suggest that the model-based approach is essential to better understand natural acidophilic microbial communities.

Colloidal precipitates related to Acid Mine Drainage: bacterial diversity and micro fungi-heavy metal interactions

NASA Astrophysics Data System (ADS)

Lucchetti, G.; Carbone, C.; Consani, S.; Zotti, M.; Di Piazza, S.; Pozzolini, M.; Giovine, M.

2015-12-01

In Acid Mine Drainage (AMD) settings colloidal precipitates control the mobility of Potential Toxic Elements (PTEs). Mineral-contaminant relationships (i.e. adsorption, ion-exchange, desorption) are rarely pure abiotic processes. Microbes, mainly bacteria and microfungi, can catalyze several reactions modifying the element speciation, as well as the bioavailability of inorganic pollutants. Soil, sediments, and waters heavily polluted with PTEs through AMD processes are a potential reservoir of extremophile bacteria and fungi exploitable for biotechnological purposes. Two different AMD related colloids, an ochraceous precipitate (deposited in weakly acidic conditions, composed by nanocrystalline goethite) and a greenish-blue precipitate (deposited at near-neutral pH, composed by allophane + woodwardite) were sampled. The aims of this work were to a) characterize the mycobiota present in these colloidal minerals by evaluating the presence of alive fungal propagules and extracting bacteria DNA; b) verify the fungal strains tolerance, and bioaccumulation capability on greenish-blue and ZnSO4 enriched media; c) evaluate potential impact of bacteria in the system geochemistry. The preliminary results show an interesting and selected mycobiota able to survive under unfavourable environmental conditions. A significant number of fungal strains were isolated in pure culture. Among them, species belonging to Penicillium and Trichoderma genera were tested on both greenish-blue and ZnSO4 enriched media. The results show a significant tolerance and bioaccumulation capability to some PTEs. The same colloidal precipitates were processed to extract bacteria DNA by using a specific procedure developed for sediments. The results give a good yield of nucleic acids and a positive PCR amplification of 16S rDNA accomplished the first step for future metagenomic analyses.

Injection of coal combustion byproducts into the Omega Mine for the reduction of acid mine drainage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gray, T.A.; Moran, T.C.; Broschart, D.W.

1998-12-31

The Omega Mine Complex is located outside of Morgantown, West Virginia. The mine is in the Upper Freeport Coal, an acid-producing coal seam. The coal was mined in a manner that has resulted in acid mine drainage (AMD) discharges at multiple points. During the 1990`s, the West Virginia Division of Environmental Protection (WVDEP) assumed responsibility for operating a collection and treatment system for the AMD. Collection and treatment costs are approximately $300,000 per year. An innovative procedure of injecting grout into the mine workings to reduce AMD and the resulting treatment costs is proposed. The procedure involves injecting grout mixesmore » composed primarily of coal combustion byproducts (CCB`s) and water, with a small quantity of cement. The intention of the injection program is to fill the mine voids in the north lobe of the Omega Mine (an area where most of the acidity is believed to be generated) with the grout, thus reducing the contact of air and water with potentially acidic material. The grout mix design consists of an approximate 1:1 ratio of fly ash to byproducts from fluidized bed combustion. Approximately 100 gallons of water per cubic yard of grout is used to help achieve flowability. Observation of the mine workings via subsurface borings and downhole video camera operation confirmed that first-mined areas were generally open while second-mined areas were generally partially collapsed. Closer injection hole spacing was used in second-mined areas to account for collapsed workings. The construction documents have been prepared with the project being bid in late 1997. The engineer`s cost estimate was approximately $2,500,000, with the low bid of approximately $2,300,000 being submitted by Howard Concrete Pumping of Bridgeville, PA.« less

Fate of the naturally occurring radioactive materials during treatment of acid mine drainage with coal fly ash and aluminium hydroxide.

PubMed

Madzivire, Godfrey; Maleka, Peane P; Vadapalli, Viswanath R K; Gitari, Wilson M; Lindsay, Robert; Petrik, Leslie F

2014-01-15

Mining of coal is very extensive and coal is mainly used to produce electricity. Coal power stations generate huge amounts of coal fly ash of which a small amount is used in the construction industry. Mining exposes pyrite containing rocks to H2O and O2. This results in the oxidation of FeS2 to form H2SO4. The acidic water, often termed acid mine drainage (AMD), causes dissolution of potentially toxic elements such as, Fe, Al, Mn and naturally occurring radioactive materials such as U and Th from the associated bedrock. This results in an outflow of AMD with high concentrations of sulphate ions, Fe, Al, Mn and naturally occurring radioactive materials. Treatment of AMD with coal fly ash has shown that good quality water can be produced which is suitable for irrigation purposes. Most of the potentially toxic elements (Fe, Al, Mn, etc) and substantial amounts of sulphate ions are removed during treatment with coal fly ash. This research endeavours to establish the fate of the radioactive materials in mine water with coal fly ash containing radioactive materials. It was established that coal fly ash treatment method was capable of removing radioactive materials from mine water to within the target water quality range for drinking water standards. The alpha and beta radioactivity of the mine water was reduced by 88% and 75% respectively. The reduced radioactivity in the mine water was due to greater than 90% removal of U and Th radioactive materials from the mine water after treatment with coal fly ash as ThO2 and UO2. No radioisotopes were found to leach from the coal fly ash into the mine water. Copyright © 2013 Elsevier Ltd. All rights reserved.

The role of chemical and physical watershed processes in the remediation of AMD impacted streams

NASA Astrophysics Data System (ADS)

Lopez, D. A. L.; Kruse, N.; Bowman, J.

2016-12-01

Thousands of miles of streams in the United States are impacted by acid mine drainage (AMD) produced by the exploitation of metal and coal mines. Several methods of remediation are used to improve the water quality and recover the diversity in the aquatic life. One of these methods is the addition of alkaline materials to the stream to neutralize the water, precipitate minerals of heavy metals, and rise the pH. Parameters that are usually considered to determine the load of alkalinity to remediate the water include the acidity and flow of the source(s), and concentration of heavy metals. However, recent studies in AMD remediated streams in SE Ohio suggest that the evolution of the water and sediment chemistry along the stream after remediation is also important, and than that evolution depends no only in the added alkalinity but also in the physical and chemical characteristics of the impacted stream. Retention of precipitated fine-grained sediments is important to improve the physical environment for the aquatic life downstream. If sediment retention ponds cannot be constructed, the occurrence of areas where sediments can be deposited and stored is determined by the topographic gradient of the stream. A detailed high-resolution profile of the stream should be constructed to identify regions where the sediments can be retained. The addition of water, dissolved and suspended matter from tributaries to the main stem should also be considered. Tributaries can provide additional alkalinity or acidity to the stream helping to the remediation process or making it more difficult. Groundwater discharges to the stream can also provide either additional alkalinity or acidity to the stream, affecting the chemical budget. These additions from surface and/or groundwater can play an important role in stream recovery. A budget of alkalinity, acidity, and other chemical species along the impacted stream can provide important information to predict the effect of alkaline additions in stream recovery. Studies prior to remediation should not concentrate in the source alone but to consider the whole watershed impacted by the AMD sources.

Treatment of combined acid mine drainage (AMD)--flotation circuit effluents from copper mine via Fenton's process.

PubMed

Mahiroglu, Ayse; Tarlan-Yel, Esra; Sevimli, Mehmet Faik

2009-07-30

The treatability of a copper mine wastewater, including heavy metals, AMD, as well as flotation chemicals, with Fenton process was investigated. Fenton process seems advantageous for this treatment, because of Fe(2+) content and low pH of AMD. First, optimum Fe(2+) condition under constant H(2)O(2) was determined, and initial Fe(2+) content of AMD was found sufficient (120 mg/L for removal of chemical oxygen demand (COD) of 6125 mg/L). In the second step, without any additional Fe(2+), optimum H(2)O(2) dosage was determined as 40 mg/L. Fe(2+)/H(2)O(2) molar ratio of 1.8 was enough to achieve the best treatment performance. In all trials, initial pH of AMD was 4.8 and pH adjustment was not performed. Utilization of existing pH and Fe(2+), low H(2)O(2) requirements, and up to 98% treatment performances in COD, turbidity, color, Cu(2+), Zn(2+) made the proposed treatment system promising. Since the reaction occurs stepwise, a two-step kinetic model was applied and calculated theoretical maximum removal rate was consistent to experimental one, which validates the applied model. For the optimum molar ratio (1.8), 140 mL/L sludge of high density (1.094 g/mL), high settling velocity (0.16 cm/s) with low specific resistance (3.15 x 10(8)m/kg) was obtained. High reaction rates and easily dewaterable sludge characteristics also made the proposed method advantageous.

Visual function assessment in simulated real-life situations in patients with age-related macular degeneration compared to normal subjects.

PubMed

Barteselli, G; Gomez, M L; Doede, A L; Chhablani, J; Gutstein, W; Bartsch, D-U; Dustin, L; Azen, S P; Freeman, W R

2014-10-01

To evaluate visual function variations in eyes with age-related macular degeneration (AMD) compared to normal eyes under different light/contrast conditions using a time-dependent visual acuity testing instrument, the Central Vision Analyzer (CVA). Overall, 37 AMD eyes and 35 normal eyes were consecutively tested with the CVA after assessing best-corrected visual acuity (BCVA) using ETDRS charts. The CVA established visual thresholds for three mesopic environments (M1 (high contrast), M2 (medium contrast), and M3 (low contrast)) and three backlight-glare environments (G1 (high contrast, equivalent to ETDRS), G2 (medium contrast), and G3 (low contrast)) under timed conditions. Vision drop across environments was calculated, and repeatability of visual scores was determined. BCVA significantly reduced with decreasing contrast in all eyes. M1 scores for BCVA were greater than M2 and M3 (P<0.001); G1 scores were greater than G2 and G3 (P<0.01). BCVA dropped more in AMD eyes than in normal eyes between M1 and M2 (P=0.002) and between M1 and M3 (P=0.003). In AMD eyes, BCVA was better using ETDRS charts compared to G1 (P<0.001). The drop in visual function between ETDRS and G1 was greater in AMD eyes compared to normal eyes (P=0.004). Standard deviations of test-retest ranged from 0.100 to 0.139 logMAR. The CVA allowed analysis of the visual complaints that AMD patients experience with different lighting/contrast time-dependent conditions. BCVA changed significantly under different lighting/contrast conditions in all eyes, however, AMD eyes were more affected by contrast reduction than normal eyes. In AMD eyes, timed conditions using the CVA led to worse BCVA compared to non-timed ETDRS charts.

Biological attenuation of arsenic and iron in a continuous flow bioreactor treating acid mine drainage (AMD).

PubMed

Fernandez-Rojo, L; Héry, M; Le Pape, P; Braungardt, C; Desoeuvre, A; Torres, E; Tardy, V; Resongles, E; Laroche, E; Delpoux, S; Joulian, C; Battaglia-Brunet, F; Boisson, J; Grapin, G; Morin, G; Casiot, C

2017-10-15

Passive water treatments based on biological attenuation can be effective for arsenic-rich acid mine drainage (AMD). However, the key factors driving the biological processes involved in this attenuation are not well-known. Here, the efficiency of arsenic (As) removal was investigated in a bench-scale continuous flow channel bioreactor treating As-rich AMD (∼30-40 mg L -1 ). In this bioreactor, As removal proceeds via the formation of biogenic precipitates consisting of iron- and arsenic-rich mineral phases encrusting a microbial biofilm. Ferrous iron (Fe(II)) oxidation and iron (Fe) and arsenic removal rates were monitored at two different water heights (4 and 25 mm) and with/without forced aeration. A maximum of 80% As removal was achieved within 500 min at the lowest water height. This operating condition promoted intense Fe(II) microbial oxidation and subsequent precipitation of As-bearing schwertmannite and amorphous ferric arsenate. Higher water height slowed down Fe(II) oxidation, Fe precipitation and As removal, in relation with limited oxygen transfer through the water column. The lower oxygen transfer at higher water height could be partly counteracted by aeration. The presence of an iridescent floating film that developed at the water surface was found to limit oxygen transfer to the water column and delayed Fe(II) oxidation, but did not affect As removal. The bacterial community structure in the biogenic precipitates in the bottom of the bioreactor differed from that of the inlet water and was influenced to some extent by water height and aeration. Although potential for microbial mediated As oxidation was revealed by the detection of aioA genes, removal of Fe and As was mainly attributable to microbial Fe oxidation activity. Increasing the proportion of dissolved As(V) in the inlet water improved As removal and favoured the formation of amorphous ferric arsenate over As-sorbed schwertmannite. This study proved the ability of this bioreactor-system to treat extreme As concentrations and may serve in the design of future in-situ bioremediation system able to treat As-rich AMD. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of Abandoned Coal-Mine Drainage on Streamflow and Water Quality in the Shamokin Creek Basin, Northumberland and Columbia Counties, Pennsylvania, 1999-2001

USGS Publications Warehouse

Cravotta,, Charles A.; Kirby, Carl S.

2003-01-01

This report assesses the contaminant loading, effects to receiving streams, and possible remedial alternatives for abandoned mine drainage (AMD) within the upper Shamokin Creek Basin in east-central Pennsylvania. The upper Shamokin Creek Basin encompasses an area of 54 square miles (140 square kilometers) within the Western Middle Anthracite Field, including and upstream of the city of Shamokin. Elevated concentrations of acidity, metals, and sulfate in the AMD from flooded underground anthracite coal mines and (or) unreclaimed culm (waste rock) piles degrade the aquatic ecosystem and water quality of Shamokin Creek to its mouth and along many of its tributaries within the upper basin. Despite dilution by unpolluted streams that more than doubles the streamflow of Shamokin Creek in the lower basin, AMD contamination and ecological impairment persist to its mouth on the Susquehanna River at Sunbury, 20 miles (32 kilometers) downstream from the mined area. Aquatic ecological surveys were conducted by the U.S. Geological Survey (USGS) in cooperation with Bucknell University (BU) and the Northumberland County Conservation District (NCCD) at six stream sites in October 1999 and repeated in 2000 and 2001 on Shamokin Creek below Shamokin and at Sunbury. In 1999, fish were absent from Quaker Run and Shamokin Creek upstream of its confluence with Carbon Run; however, creek chub (Semotilus atromaculatus) were present within three sampled reaches of Carbon Run. During 1999, 2000, and 2001, six or more species of fish were identified in Shamokin Creek below Shamokin and at Sunbury despite elevated concentrations of dissolved iron and ironencrusted streambeds at these sites. Data on the flow rate and chemistry for 46 AMD sources and 22 stream sites throughout the upper basin plus 1 stream site at Sunbury were collected by the USGS with assistance from BU and the Shamokin Creek Restoration Alliance (SCRA) during low base-flow conditions in August 1999 and high baseflow conditions in March 2000. The water-quality data were used to determine priority ranks of the AMD sources on the basis of loadings of iron, manganese, and aluminum and to identify possible remedial alternatives, including passive-treatment options, for consideration by water-resource managers. The ranking sequence for the top AMD sources based on the high base-flow data generally matched that based on the low base-flow data. The contaminant loadings generally increased with flow, and 10 previously identified intermittent AMD sources were not discharging during the low base-flow sampling period. The top 3 AMD sources (SR19, SR12, and SR49) on the basis of dissolved metals loading in March 2000 accounted for more than 50 percent of the metals loading to Shamokin Creek, whereas the top 15 AMD sources accounted for more than 98 percent of the metals loading. When sampled in March 2000, these AMD sources had flow rates ranging from 0.7 to 19 cubic feet per second (1,138 to 32,285 liters per minute) and pH from 3.5 to 6.1 standard units. Only 1 of the top 15 AMD sources (SR21) was net alkaline (alkalinity > acidity); the others were net acidic and will require additional alkalinity to facilitate metals removal and maintain near-neutral pH. For the top 15 AMD sources, dissolved iron was the principal source of acidity and metals loading; concentrations of iron ranged from 10 to 57 milligrams per liter. Dissolved manganese ranged from 1.9 to 7.4 milligrams per liter. Dissolved aluminum exceeded 3.9 milligrams per liter at seven of the sites but was less than 0.2 milligram per liter at seven others. Alkalinity can be acquired by the dissolution of limestone and (or) bacterial sulfate reduction within various passive-treatment systems including anoxic or oxic limestone drains, limestone- lined channels, or compost wetlands. Subsequently, the gradual oxidation and consequent precipitation of iron and manganese can be accommodated within settling ponds or aerobic wetlands. Assum

Pervious concrete reactive barrier for removal of heavy metals from acid mine drainage - column study.

PubMed

Shabalala, Ayanda N; Ekolu, Stephen O; Diop, Souleymane; Solomon, Fitsum

2017-02-05

This paper presents a column study conducted to investigate the potential use of pervious concrete as a reactive barrier for treatment of water impacted by mine waste. The study was done using acid mine drainage (AMD) collected from a gold mine (WZ) and a coalfield (TDB). Pervious concrete mixtures consisting of Portland cement CEM I 52.5R with or without 30% fly ash (FA) were prepared at a water-cementitious ratio of 0.27 then used to make cubes which were employed in the reactor columns. It was found that the removal efficiency levels of Al, Fe, Mn, Co and Ni were 75%, 98%, 99%, 94% and 95% for WZ; 87%, 96%, 99%, 98% and 90% for TDB, respectively. The high rate of acid reduction and metal removal by pervious concrete is attributed to dissolution of portlandite which is a typical constituent of concrete. The dominant reaction product in all four columns was gypsum, which also contributed to some removal of sulphate from AMD. Formation of gypsum, goethite, and Glauber's salt were identified. Precipitation of metal hydroxides seems to be the dominant metal removal mechanism. Use of pervious concrete offers a promising alternative treatment method for polluted or acidic mine water. Copyright © 2016 Elsevier B.V. All rights reserved.

Bioaccumulation of metals in reeds collected from an acid mine drainage contaminated site in winter and spring.

PubMed

Guo, Lin; Cutright, Teresa J

2016-01-01

Wetland plants such as Phragmites australis has been used to treat acid mine drainage (AMD) contaminated soil which is a serious environmental issue worldwide. This project investigated metal plaque content(s) and metal uptake in reeds grown in an AMD field in winter and spring. The results indicated that the level of Fe plaque was much higher than Mn and Al plaque as the soil contained more Fe than Al and Mn. The amounts of Mn and Al plaque formed on reeds in spring were not significantly different from that in winter (p > .05). However, more Fe plaque was formed on reeds collected in spring. The concentrations of metals in underground organs were positively related to the metal levels in soils. More Mn and Al transferred to the aboveground tissues of reeds during the spring while the Fe levels in reeds did not significantly vary with seasons. Roots and rhizomes were the main organs for Fe sequestration (16.3 ± 4.15 mg/g in roots in spring) while most Al was sequestered in the shoots of reeds (2.05 ± 0.09 mg/g in shoots in spring). Further research may be needed to enhance the translocation of metals in reeds and increase the phytoremediation efficiency.

Mineralogical characteristics of sediments and heavy metal mobilization along a river watershed affected by acid mine drainage.

PubMed

Xie, Yingying; Lu, Guining; Yang, Chengfang; Qu, Lu; Chen, Meiqin; Guo, Chuling; Dang, Zhi

2018-01-01

Trace-element concentrations in acid mine drainage (AMD) are primarily controlled by the mineralogy at the sediment-water interface. Results are presented for a combined geochemical and mineralogical survey of Dabaoshan Mine, South China. Developed sequential extraction experiments with the analysis of the main mineralogical phases by semi-quantitative XRD, differential X-ray diffraction (DXRD) and scanning electron microscopy (SEM) were conducted to identify the quantitative relationship between iron minerals and heavy metals. Results showed that schwertmannite, jarosite, goethite and ferrihydrite were the dominant Fe-oxyhydroxide minerals which were detected alternately in the surface sediment with the increasing pH from 2.50 to 6.93 along the Hengshi River. Decreasing contents of schwertmannite ranging from 35 wt % to 6.5 wt % were detected along the Hengshi River, which was corresponding to the decreasing metal contents. The easily reducible fractions exert higher affinity of metals while compared with reducible and relatively stable minerals. A qualitative analysis of heavy metals extracted from the sediments indicated that the retention ability varied: Pb > Mn > Zn > As ≈ Cu > Cr > Cd ≈ Ni. Results in this study are avail for understanding the fate and transport of heavy metals associated with iron minerals and establishing the remediation strategies of AMD systems.

Mineralogical characteristics of sediments and heavy metal mobilization along a river watershed affected by acid mine drainage

PubMed Central

Xie, Yingying; Yang, Chengfang; Qu, Lu; Chen, Meiqin; Guo, Chuling; Dang, Zhi

2018-01-01

Trace-element concentrations in acid mine drainage (AMD) are primarily controlled by the mineralogy at the sediment-water interface. Results are presented for a combined geochemical and mineralogical survey of Dabaoshan Mine, South China. Developed sequential extraction experiments with the analysis of the main mineralogical phases by semi-quantitative XRD, differential X-ray diffraction (DXRD) and scanning electron microscopy (SEM) were conducted to identify the quantitative relationship between iron minerals and heavy metals. Results showed that schwertmannite, jarosite, goethite and ferrihydrite were the dominant Fe-oxyhydroxide minerals which were detected alternately in the surface sediment with the increasing pH from 2.50 to 6.93 along the Hengshi River. Decreasing contents of schwertmannite ranging from 35 wt % to 6.5 wt % were detected along the Hengshi River, which was corresponding to the decreasing metal contents. The easily reducible fractions exert higher affinity of metals while compared with reducible and relatively stable minerals. A qualitative analysis of heavy metals extracted from the sediments indicated that the retention ability varied: Pb > Mn > Zn > As ≈ Cu > Cr > Cd ≈ Ni. Results in this study are avail for understanding the fate and transport of heavy metals associated with iron minerals and establishing the remediation strategies of AMD systems. PMID:29304091

Bacterial Influence on the Solubility of Cinnabar and Metacinnabar at New Idria, CA

NASA Astrophysics Data System (ADS)

Jew, A. D.; Rytuba, J. J.; Spormann, A. M.; Brown, G. E.

2007-12-01

Mercury in the forms of cinnabar (α-HgS) and metacinnabar (β-HgS) is generally considered to be unreactive and of little environmental concern. To determine if this current belief is valid, a consortium of bacteria (including a Thiomonas intermedia-like bacterium) was taken from the acid mine drainage (AMD) pond at the New Idria Hg Mine, San Benito Co., CA, and inoculated into filter-sterilized AMD pond water (pH = 4) containing either ground cinnabar or metacinnabar crystals (<45 μm in diameter), with sampling occurring every 3 days. Under aerobic conditions the samples showed a pronounced increase in aqueous Hg concentration over background water concentrations (350(±20)ng/L). Bacteria growing on α-HgS increased the Hg concentration to 597(±10)μg/L, while bacteria growing on β-HgS resulted in levels of 8.0(±0.2)mg/L; both maxima occurred after 18 days of incubation. Experiments conducted with (1) α- HgS or β-HgS in the presence of killed bacteria (anaerobic), (2) α-HgS with pond water (abiotic), and (3) β-HgS with AMD pond water (abiotic) showed drops in aqueous Hg to below the detection limit (0.1ng/L) within 12 days. Anaerobic growth of the bacterial consortium showed a pattern similar to those of the abiotic water-HgS experiments, except that Hg levels dropped below detection limit within 6 days. These combined results suggest that HgS degradation by this bacterial consortium is an aerobic process. Killed bacteria incubated aerobically showed a slight increase in Hg levels over background water levels (<10x increase) then dropped below detection limit. This observation suggests that enzymes might be involved in the dissolution of HgS and were still viable for ~6 days after sterilization. In aerobic living incubations, the activities of different mercury and sulfide species were estimated using the thermodynamic modeling program Minteq with AMD pond water chemistry determined by ICP-MS and total mercury and total sulfide analyses. These calculations give an equilibrium solubility product for the dissolution of HgS up to 25 orders of magnitude higher than HgS under standard conditions. When compared to calculations by Paquette et al., 1997 and Benoit et al., 1999, the bacterial consortium at New Idria causes an increase in the pK for all reported reactions including H+, HS-, and H2S of 11-13 orders of magnitude. These results indicate that the biofilm consortium at the New Idria AMD pond has a profound effect on the solubility of cinnabar and metacinnabar, suggesting that a reassessment of HgS stability in aerobic AMD environments is needed.

Heavy metals content in acid mine drainage at abandoned and active mining area

NASA Astrophysics Data System (ADS)

Hatar, Hazirah; Rahim, Sahibin Abd; Razi, Wan Mohd; Sahrani, Fathul Karim

2013-11-01

This study was conducted at former Barite Mine, Tasik Chini and former iron mine Sungai Lembing in Pahang, and also active gold mine at Lubuk Mandi, Terengganu. This study was conducted to determine heavy metals content in acid mine drainage (AMD) at the study areas. Fourteen water sampling stations within the study area were chosen for this purpose. In situ water characteristic determinations were carried out for pH, electrical conductivity (EC), redox potential (ORP) and total dissolved solid (TDS) using multi parameter YSI 556. Water samples were collected and analysed in the laboratory for sulfate, total acidity and heavy metals which follow the standard methods of APHA (1999) and HACH (2003). Heavy metals in the water samples were determined directly using Inductive Coupled Plasma Mass Spectrometry (ICP-MS). Data obtained showed a highly acidic mean of pH values with pH ranged from 2.6 ± 0.3 to 3.2 ± 0.2. Mean of electrical conductivity ranged from 0.57 ± 0.25 to 1.01 ± 0.70 mS/cm. Redox potential mean ranged from 487.40 ± 13.68 to 579.9 ± 80.46 mV. Mean of total dissolved solids (TDS) in AMD ranged from 306.50 ± 125.16 to 608.14 ± 411.64 mg/L. Mean of sulfate concentration in AMD ranged from 32.33 ± 1.41 to 207.08 ± 85.06 mg/L, whereas the mean of total acidity ranged from 69.17 ± 5.89 to 205.12 ± 170.83 mgCaCO3/L. Heavy metals content in AMD is dominated by Fe, Cu, Mn and Zn with mean concentrations range from 2.16 ± 1.61 to 36.31 ± 41.02 mg/L, 0.17 ± 0.13 to 11.06 ± 2.85 mg/L, 1.12 ± 0.65 to 7.17 ± 6.05 mg/L and 0.62 ± 0.21 to 6.56 ± 4.11 mg/L, respectively. Mean concentrations of Ni, Co, As, Cd and Pb were less than 0.21, 0.51, 0.24, 0.05 and 0.45 mg/L, respectively. Significant correlation occurred between Fe and Mn, Cu, Zn, Co and Cd. Water pH correlated negatively with all the heavy metals, whereas total acidity, sulfate, total dissolved solid, and redox potential correlated positively. The concentration of heavy metals in the AMD appeared to be influenced by acidity and the formation of Fe, Mn oxide and hydroxide.

Sustainable Management of Flowback Water during Hydraulic Fracturing of Marcellus Shale for Natural Gas Production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vidic, Radisav

2015-01-24

This study evaluated the feasibility of using abandoned mine drainage (AMD) as make- up water for the reuse of produced water for hydraulic fracturing. There is an abundance of AMD sources near permitted gas wells as documented in this study that can not only serve as makeup water and reduce the demand on high quality water resources but can also as a source of chemicals to treat produced water prior to reuse. The assessment of AMD availability for this purpose based on proximity and relevant regulations was accompanied by bench- and pilot-scale studies to determine optimal treatment to achieve desiredmore » water quality for use in hydraulic fracturing. Sulfate ions that are often present in AMD at elevated levels will react with Ba²⁺ and Sr²⁺ in produced water to form insoluble sulfate compounds. Both membrane microfiltration and gravity separation were evaluated for the removal of solids formed as a result of mixing these two impaired waters. Laboratory studies revealed that neither AMD nor barite formed in solution had significant impact on membrane filtration but that some produced waters contained submicron particles that can cause severe fouling of microfiltration membrane. Coagulation/flocculation was found to be an effective process for the removal of suspended solids and both bench- and pilot-scale studies revealed that optimal process conditions can consistently achieve the turbidity of the finished water below 5 NTU. Adjusting the blending ratio of AMD and produced water can achieve the desired effluent sulfate concentration that can be accurately predicted by chemical thermodynamics. Co-treatment of produced water and AMD will result in elevated levels of naturally occurring radioactive materials (NORM) in the solid waste generated in this process due to radium co-precipitation with barium sulfate. Laboratory studies revealed that the mobility of barite that may form in the subsurface due to the presence of sulfate in the fracturing fluid can be controlled by the addition of appropriate antiscalants.« less

Remediation of AMD using natural and waste material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Basir, Nur Athirah Mohamad; Yaacob, Wan Zuhairi Wan

2014-09-03

Acid Mine Drainage (AMD) is highly acidic, sulphate rich and frequently carries a high transition metal and heavy metal burden. These AMD's eventually migrate into streams and rivers and impact negatively on the quality of these water bodies. So it is dire necessary to treat this AMD. Various materials such as ladle furnace slag (LFS), bentonite, zeolite, active carbon and kaolinite are currently available to remove heavy metals from contaminated water. All these materials are capable to rise up the pH value and adsorb heavy metals. The process is divided into two stages; screening test and tank experiment. Screening testmore » is conduct by using Batch Equilibrium Test (BET), X-Ray Fluorescene (XRF) identification also Scanning Electron Microscopic (SEM) characteristic. The results showed that all the concentration of heavy metal are decreasing extremely and pH value rise up except for kaolinite. From screening test only ladle furnace slag, bentonite, zeolite and active carbon are chosen for the tank experiment. Tank experiment design with 18cm (H) X 15cm (L) X 15cm (H) was made by silica glass. All these treatment materials were stirred in the tank for 30 days. Initial pH for all tanks is 2.4 and after 30 days is changing into 6.11, 3.91, 2.98 and 2.71 for LFS, bentonite, active carbon as well as zeolite respectively. LFS is the best material for absorption of Zn, Mn and Cu in the synthetic solution. Meanwhile, bentonite is the best absorbent for Ni, Fe and Cd. The conclusion shows that LFS might have big potentials to control AMD pollution base on neutralize pH resulting in a great improvement in the quality of the water.« less

Remediation of AMD using natural and waste material

NASA Astrophysics Data System (ADS)

Basir, Nur Athirah Mohamad; Yaacob, Wan Zuhairi Wan

2014-09-01

Acid Mine Drainage (AMD) is highly acidic, sulphate rich and frequently carries a high transition metal and heavy metal burden. These AMD's eventually migrate into streams and rivers and impact negatively on the quality of these water bodies. So it is dire necessary to treat this AMD. Various materials such as ladle furnace slag (LFS), bentonite, zeolite, active carbon and kaolinite are currently available to remove heavy metals from contaminated water. All these materials are capable to rise up the pH value and adsorb heavy metals. The process is divided into two stages; screening test and tank experiment. Screening test is conduct by using Batch Equilibrium Test (BET), X-Ray Fluorescene (XRF) identification also Scanning Electron Microscopic (SEM) characteristic. The results showed that all the concentration of heavy metal are decreasing extremely and pH value rise up except for kaolinite. From screening test only ladle furnace slag, bentonite, zeolite and active carbon are chosen for the tank experiment. Tank experiment design with 18cm (H) X 15cm (L) X 15cm (H) was made by silica glass. All these treatment materials were stirred in the tank for 30 days. Initial pH for all tanks is 2.4 and after 30 days is changing into 6.11, 3.91, 2.98 and 2.71 for LFS, bentonite, active carbon as well as zeolite respectively. LFS is the best material for absorption of Zn, Mn and Cu in the synthetic solution. Meanwhile, bentonite is the best absorbent for Ni, Fe and Cd. The conclusion shows that LFS might have big potentials to control AMD pollution base on neutralize pH resulting in a great improvement in the quality of the water.

Size and performance of anoxic limestone drains to neutralize acdic mine drainagei

USGS Publications Warehouse

Cravotta, C.A.

2003-01-01

Acidic mine drainage (AMD) can be neutralized effectively in underground, anoxic limestone drains (ALDs). Owing to reaction between the AMD and limestone (CaCO3), the pH and concentrations of alkalinity and calcium increase asymptotically with detention time in the ALD, while concentrations of sulfate, ferrous iron, and manganese typically are unaffected. This paper introduces a method to predict the alkalinity produced within an ALD and to estimate the mass of limestone required for its construction on the basis of data from short-term, closed-container (cubitainer) tests. The cubitainer tests, which used an initial mass of 4 kg crushed limestone completely inundated with 2.8 L AMD, were conducted for 11 to 16 d and provided estimates for the initial and maximum alkalinities and corresponding rates of alkalinity production and limestone dissolution. Long-term (5-11 yr) data for alkalinity and CaCO3 flux at the Howe Bridge, Morrison, and Buck Mountain ALDs in Pennsylvania, USA, indicate that rates of alkalinity production and limestone dissolution under field conditions were comparable with those in cubitainers filled with limestone and AMD from each site. The alkalinity of effluent and intermediate samples along the flow path through the ALDs and long-term trends in the residual mass of limestone and the effluent alkalinity were estimated as a function of the computed detention time within the ALD and second-order dissolution rate models for cubitainer tests. Thus, cubitainer tests can be a useful tool for designing ALDs and predicting their performance.

Removal of metal from acid mine drainage using a hybrid system including a pipes inserted microalgae reactor.

PubMed

Park, Young-Tae; Lee, Hongkyun; Yun, Hyun-Shik; Song, Kyung-Guen; Yeom, Sung-Ho; Choi, Jaeyoung

2013-12-01

In this study, the microalgae culture system to combined active treatment system and pipe inserted microalgae reactor (PIMR) was investigated. After pretreated AMD in active treatment system, the effluent load to PIMR in order to Nephroselmis sp. KGE 8 culture. In experiment, effect of iron on growth and lipid accumulation in microalgae were inspected. The 2nd pretreatment effluent was economic feasibility of microalgae culture and lipid accumulation. The growth kinetics of the microalgae are modeled using logistic growth model and the model is primarily parameterized from data obtained through an experimental study where PIMR were dosed with BBM, BBM added 10 mg L(-1) iron and 2nd pretreatment effluent. Moreover, the continuous of microalgae culture in PIMR can be available. Overall, this study indicated that the use of pretreated AMD is a viable method for culture microalgae and lipid accumulation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effect of citric acid and rhizosphere bacteria on metal plaque formation and metal accumulation in reeds in synthetic acid mine drainage solution.

PubMed

Guo, Lin; Cutright, Teresa J

2014-06-01

Many of regions in the world have been affected by acid mine drainage (AMD). The study assessed the effect of rhizosphere bacteria and citric acid (CA) on the metal plaque formation and heavy metal uptake in Phragmites australis cultured in synthetic AMD solution. Mn and Al plaque were not formed, but Fe plaque which was mediated by rhizosphere iron oxidizing bacteria (Fe(II)OB) was observed on the root system of reeds. Fe plaque did not significantly influence the uptake of Fe, Al and Mn into tissues of reeds. CA significantly (p<0.01) inhibited the growth of Fe(II)OB and decreased the formation of Fe plaque. CA also significantly improved (p<0.05) the accumulation of Fe, Mn and Al in all the tissues of reeds. Roots and rhizomes were the main organs to store metals. The roots contained 0.08±0.01mg/g Mn, 2.39±0.26mg/g Fe and 0.19±0.02mg/g Al, while the shoots accumulated 0.04±0.00mg/g Mn, 0.20±0.01mg/g Fe, 0.11±0.00mg/g Al in reeds cultured in solution amended with 2.101g/l CA and without inoculation of rhizosphere bacteria. Copyright © 2014 Elsevier Inc. All rights reserved.

Analysis of Biogeochemistry of Acid-Mine Drainage at Rowe, Massachusetts

NASA Astrophysics Data System (ADS)

Ahlfeld, D. P.; Yuretich, R.; Ergas, S.; Nusslein, K.; Feldman, A.

2003-12-01

Acid waters rich in iron and sulfate can support a wide variety of microorganisms that catalyze the oxidation-reduction reactions of these bioactive elements, exemplified by acid-mine drainage (AMD). In order to study the biogeochemistry of natural attenuation a field site has been established at Davis Mine, an abandoned pyrite mine in rural Rowe Massachusetts. This site is of particular interest because of the apparent dynamic equilibrium that has restricted the extent of the AMD in this area since the mine was closed nearly 100 years ago. Initial evidence suggests that sulfate reduction is occurring at the fringes of the site. Multi-level monitoring wells and surface water sampling points have been installed. Soil samples collected from the drilled wells are being used to provide inoculums for cultivating bacteria and identifying DNA. Preliminary data indicate a restricted lens of impacted groundwater that moves rapidly through the mine tailings and shallow bedrock fractures, but is contained by ambient groundwater from uncontaminated recharge areas. Sulfate reduction has been documented at the margins of the acid-generating area, and this has been reproduced in laboratory experiments. Current research is now examining the processes of Fe(III) and SO4 reduction and the roles of acidophilic and acid-tolerant anaerobic microorganisms. K12 teachers are part of the research teams and the effects of research experiences on their higher-level understanding of science are being evaluated.

Strontium isotope quantification of siderite, brine and acid mine drainage contributions to abandoned gas well discharges in the Appalachian Plateau

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chapman, Elizabeth C.; Capo, Rosemary C.; Stewart, Brian W.

2013-04-01

Unplugged abandoned oil and gas wells in the Appalachian region can serve as conduits for the movement of waters impacted by fossil fuel extraction. Strontium isotope and geochemical analysis indicate that artesian discharges of water with high total dissolved solids (TDS) from a series of gas wells in western Pennsylvania result from the infiltration of acidic, low Fe (Fe < 10 mg/L) coal mine drainage (AMD) into shallow, siderite (iron carbonate)-cemented sandstone aquifers. The acidity from the AMD promotes dissolution of the carbonate, and metal- and sulfate-contaminated waters rise to the surface through compromised abandoned gas well casings. Strontium isotopemore » mixing models suggest that neither upward migration of oil and gas brines from Devonian reservoirs associated with the wells nor dissolution of abundant nodular siderite present in the mine spoil through which recharge water percolates contribute significantly to the artesian gas well discharges. Natural Sr isotope composition can be a sensitive tool in the characterization of complex groundwater interactions and can be used to distinguish between inputs from deep and shallow contamination sources, as well as between groundwater and mineralogically similar but stratigraphically distinct rock units. This is of particular relevance to regions such as the Appalachian Basin, where a legacy of coal, oil and gas exploration is coupled with ongoing and future natural gas drilling into deep reservoirs.« less

Two-stage combined treatment of acid mine drainage and municipal wastewater.

PubMed

Deng, Dongyang; Lin, Lian-Shin

2013-01-01

This study examined the feasibility of the combined treatment of field-collected acid mine drainages (AMD, pH = 4.2 ± 0.9, iron = 112 ± 118 mg/L, sulfate = 1,846 ± 594 mg/L) and municipal wastewater (MWW, avg. chemical oxygen demand (COD) = 234-333 mg/L) using a two-stage process. The process consisted of batch mixing of the two wastes to condition the mixture solutions, followed by anaerobic biological treatment. The mixings performed under a range of AMD/MWW ratios resulted in phosphate removal of 9 to ∼100%, the mixture pH of 6.2-7.9, and COD/sulfate concentration ratio of 0.05-5.4. The biological treatment consistently removed COD and sulfate by >80% from the mixture solutions for COD/sulfate ratios of 0.6-5.4. Alkalinity was produced in the biological treatment causing increased pH and further removal of metals from the solutions. Scanning electron microscopy of produced sludge with energy dispersion analysis suggested chemical precipitation and associated adsorption and co-precipitation as the mechanisms for metal removal (Fe: >99%, Al: ∼100%, Mn: 75 to ∼100%, Ca: 52-81%, Mg: 13-76%, and Na: 56-76%). The study showed promising results for the treatment method and denoted the potential of developing innovative technologies for combined management of the two wastes in mining regions.

Distribution pattern of anthropogenic marine debris along the gastrointestinal tract of green turtles (Chelonia mydas) as implications for rehabilitation.

PubMed

Colferai, André S; Silva-Filho, Rodolfo Pinho; Martins, Aryse Moreira; Bugoni, Leandro

2017-06-15

Pollution from anthropogenic marine debris (AMD) is currently the most widely distributed and lasting anthropic impact in the marine environment, affecting hundreds of species, including all sea turtles. In this study, the patterns of AMD distribution along the gastrointestinal tract (GT) and their relationship with obstructions and faecalomas in 62 green turtles (Chelonia mydas) that died during rehabilitation in southern Brazil were determined. The GT was split in seven sections, corresponding to the natural organs and intestinal areas morphologically and physiologically distinct. Mean mass (4.24g) and area (146.74cm 2 ) of AMD in the stomach were higher than in other sections. The anterior portion of the rectum had the highest number of obstructions, followed by the stomach. AMD was associated with the obstructions, with positive correlation between faecalomas and AMD masses. Organs and subdivisions showed marked differences in susceptibility to obstructions caused by AMD, which deserves attention in clinical interventions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Abandoned mine drainage in the Swatara Creek Basin, southern anthracite coalfield, Pennsylvania, USA: 1. stream quality trends coinciding with the return of fish

USGS Publications Warehouse

Cravotta, Charles A.; Brightbill, Robin A.; Langland, Michael J.

2010-01-01

Acidic mine drainage (AMD) from legacy anthracite mines has contaminated Swatara Creek in eastern Pennsylvania. Intermittently collected base-flow data for 1959–1986 indicate that fish were absent immediately downstream from the mined area where pH ranged from 3.5 to 7.2 and concentrations of sulfate, dissolved iron, and dissolved aluminum were as high as 250, 2.0, and 4.7 mg/L, respectively. However, in the 1990s, fish returned to upper Swatara Creek, coinciding with the implementation of AMD treatment (limestone drains, limestone diversion wells, limestone sand, constructed wetlands) in the watershed. During 1996–2006, as many as 25 species of fish were identified in the reach downstream from the mined area, with base-flow pH from 5.8 to 7.6 and concentrations of sulfate, dissolved iron, and dissolved aluminum as high as 120, 1.2, and 0.43 mg/L, respectively. Several of the fish taxa are intolerant of pollution and low pH, such as river chub (Nocomis icropogon) and longnose dace (Rhinichthys cataractae). Cold-water species such as brook trout (Salvelinus fontinalis) and warm-water species such as rock bass (Ambloplites rupestris) varied in predominance depending on stream flow and stream temperature. Storm flow data for 1996–2007 indicated pH, alkalinity, and sulfate concentrations decreased as the stream flow and associated storm-runoff component increased, whereas iron and other metal concentrations were poorly correlated with stream flow because of hysteresis effects (greater metal concentrations during rising stage than falling stage). Prior to 1999, pH\\5.0 was recorded during several storm events; however, since the implementation of AMD treatments, pH has been maintained near neutral. Flow-adjusted trends for1997–2006 indicated significant increases in calcium; decreases in hydrogen ion, dissolved aluminum, dissolved and total manganese, and total iron; and no change in sulfate or dissolved iron in Swatara Creek immediately downstream from the mined area. The increased pH and calcium from limestone in treatment systems can be important for mitigating toxic effects of dissolved metals. Thus, treatment of AMD during the 1990s improved pH buffering, reduced metals transport, and helped to decrease metals toxicity to fish.

Inhibition of Sulfide Mineral Oxidation by Surface Coating Agents: Batch

NASA Astrophysics Data System (ADS)

Choi, J.; Ji, M. K.; Yun, H. S.; Park, Y. T.; Gee, E. D.; Lee, W. R.; Jeon, B.-H.

2012-04-01

Mining activities and mineral industries have impacted on rapid oxidation of sulfide minerals such as pyrite (FeS2) which leads to Acid Mine Drainage (AMD) formation. Some of the abandoned mines discharge polluted water without proper environmental remediation treatments, largely because of financial constraints in treating AMD. Magnitude of the problem is considerable, especially in countries with a long history of mining. As metal sulfides become oxidized during mining activities, the aqueous environment becomes acid and rich in many metals, including iron, lead, mercury, arsenic and many others. The toxic heavy metals are responsible for the environmental deterioration of stream, groundwater and soils. Several strategies to remediate AMD contaminated sites have been proposed. Among the source inhibition and prevention technologies, microencapsulation (coating) has been considered as a promising technology. The encapsulation is based on inhibition of O2 diffusion by surface coating agent and is expected to control the oxidation of pyrite for a long time. Potential of several surface coating agents for preventing oxidation of metal sulfide minerals from both Young-Dong coal mine and Il-Gwang gold mine were examined by conducting batch experiments and field tests. Powdered pyrite as a standard sulfide mineral and rock samples from two mine outcrops were mixed with six coating agents (KH2PO4, MgO and KMnO4 as chemical agents, and apatite, cement and manganite as mineral agents) and incubated with oxidizing agents (H2O2 or NaClO). Batch experiments with Young-Dong coal mine samples showed least SO42- production in presence of KMnO4 (16% sulfate production compared to no surface coating agents) or cement (4%) within 8 days. In the case of Il-Gwang mine samples, least SO42- production was observed in presence of KH2PO4 (8%) or cement (2%) within 8 days. Field-scale pilot tests at Il-Gwang site also showed that addition of KH2PO4 decreased sulfate production from 200 to 13 mg L-1 and reduced Cu and Mn from 8 and 3 mg L-1 to below the detection limits, respectively. The experimental results suggested that the amendment of surface coating agents can be a promising alternative for inhibition of sulfide oxidation at AMD sites.

Bioremediation of Acidic and Metalliferous Drainage (AMD) through organic carbon amendment by municipal sewage and green waste.

PubMed

McCullough, Clint D; Lund, Mark A

2011-10-01

Pit lakes (abandoned flooded mine pits) represent a potentially valuable water resource in hot arid regions. However, pit lake water is often characterised by low pH with high dissolved metal concentrations resulting from Acidic and Metalliferous Drainage (AMD). Addition of organic matter to pit lakes to enhance microbial sulphate reduction is a potential cost effective remediation strategy. However, cost and availability of suitable organic substrates are often limiting. Nevertheless, large quantities of sewage and green waste (organic garden waste) are often available at mine sites from nearby service towns. We treated AMD pit lake water (pH 2.4) from tropical, North Queensland, Australia, with primary-treated sewage sludge, green waste, and a mixture of sewage and green waste (1:1) in a controlled microcosm experiment (4.5 L). Treatments were assessed at two different rates of organic loading of 16:1 and 32:1 pit water:organic matter by mass. Combined green waste and sewage treatment was the optimal treatment with water pH increased to 5.5 in only 145 days with decreases of dissolved metal concentrations. Results indicated that green waste was a key component in the pH increase and concomitant heavy metal removal. Water quality remediation was primarily due to microbially-mediated sulphate reduction. The net result of this process was removal of sulphate and metal solutes to sediment mainly as monosulfides. During the treatment process NH(3) and H(2)S gases were produced, albeit at below concentrations of concern. Total coliforms were abundant in all green waste-treatments, however, faecal coliforms were absent from all treatments. This study demonstrates addition of low-grade organic materials has promise for bioremediation of acidic waters and warrants further experimental investigation into feasibility at higher scales of application such as pit lakes. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

Geochemistry of rare earth elements in minesoils from São Domingos mining district (Iberian Pyrite Belt)

NASA Astrophysics Data System (ADS)

Delgado, Joaquin; Perez-Lopez, Rafael; Nieto, Jose Miguel; Ayora, Carles

2010-05-01

The São Domingos mine is one of the most emblematic mining districts in the lower part of the Guadiana River Basin (SW of Iberian Peninsula). It is located in Portugal (about 5 km from the Spanish border), in the northern sector of the Iberian Pyrite Belt (IPB), one of the largest metallogenetic provinces of massive sulphides in the world. Although mining activity has ceased at present, the large-scale exploitation of this deposit between the second half of the XIX century and the first half of the XX century, has favoured the production of enormous waste dumps, where oxidation of pyrite and associated sulphides is resulting in the production of acid mine drainage (AMD). Mining wastes, minesoils, and acid mine drainage have been analyzed for their major ions and rare earth elements (REE) with the aim of understanding the REE mobility during sulphide weathering so that lanthanoid series can be used both as a proxy for the extent of water-rock interaction and as a tool for identifying impacts of AMD on natural ecosystems. Chemical speciation of REE in extracts from minesoils indicates that REE sulphate complexes (mainly LnSO4+) are the primary aqueous form (60-90%), and free ionic species (Ln3+, 10-40%) are the next most abundant form of soil water-soluble fraction and controls the REE speciation model. The REE from this fraction have NASC-normalized patterns with middle-REE (MREE) enriched signature compared to the light-REE (LREE) and heavy-REE (HREE), showing convex MREE-signatures and convexity index values of +1.29 +/- 1.13. These results are consistent with the typical REE fractionation patterns reported for AMD. Poorly crystalline iron oxyhydroxysulphates act as a source of labile MREE by dissolution and/or desorption processes and could explain the MREE-enriched signatures in solution.

Evaluation of the potential of indigenous calcareous shale for neutralization and removal of arsenic and heavy metals from acid mine drainage in the Taxco mining area, Mexico.

PubMed

Romero, F M; Núñez, L; Gutiérrez, M E; Armienta, M A; Ceniceros-Gómez, A E

2011-02-01

In the Taxco mining area, sulfide mineral oxidation from inactive tailings impoundments and abandoned underground mines has produced acid mine drainage (AMD; pH 2.2-2.9) enriched in dissolved concentrations (mg l⁻¹) sulfate, heavy metals, and arsenic (As): SO₄²⁻ (pH 1470-5454), zinc (Zn; 3.0-859), iron (Fe; pH 5.5-504), copper (Cu; pH 0.7-16.3), cadmium (Cd; pH 0.3-6.7), lead (Pb; pH < 0.05-1.8), and As (pH < 0.002-0.6). Passive-treatment systems using limestone have been widely used to remediate AMD in many parts of the world. In limestone-treatment systems, calcite simultaneously plays the role of neutralizing and precipitating agent. However, the acid-neutralizing potential of limestone decreases when surfaces of the calcite particles become less reactive as they are progressively coated by metal precipitates. This study constitutes first-stage development of passive-treatment systems for treating AMD in the Taxco mine area using indigenous calcareous shale. This geologic material consists of a mixture of calcite, quartz, muscovite, albite, and montmorillonite. Results of batch leaching test indicate that calcareous shale significantly increased the pH (to values of 6.6-7.4) and decreased heavy metal and As concentrations in treated mine leachates. Calcareous shale had maximum removal efficiency (100%) for As, Pb, Cu, and Fe. The most mobile metals ions were Cd and Zn, and their average percentage removal was 87% and 89%, respectively. In this natural system (calcareous shale), calcite provides a source of alkalinity, whereas the surfaces of quartz and aluminosilicate minerals possibly serve as a preferred locus of deposition for metals, resulting in the neutralizing agent (calcite) beings less rapidly coated with the precipitating metals and therefore able to continue its neutralizing function for a longer time.

Synthesized af-PFCl and GG-g-P(AN)/TEOS hydrogel composite used in hybridized technique applied for AMD treatment

NASA Astrophysics Data System (ADS)

Fosso-Kankeu, Elvis

2018-06-01

In the present study af-PFCl, GL-g-P(AN) hydrogel and GL-g-P(AN)/TEOS hydrogel composite were synthesized. The hydrogels were characterized using the fourier transformed infra-red (FTIR) and the scanning electron microscope (SEM) techniques. The coagulant af-PFCl and the hydrogels were applied consecutively in flocculation and adsorption processes respectively for the treatment of acid mine drainage (AMD). It was observed that the grafting process increased the amount of binding groups on the hydrogels. The hybridization of the techniques assisted in the removal of anions; while the cations were mostly removed by the adsorption process. The adsorbents behaviour was fittingly expressed by the pseudo-second order model. The adsorption capacities of GL-g-P(AN)/TEOS hydrogel composite for the removal of Al, As and Zn were 3.89, 0.66 and 0.394 respectively; while the adsorption capacities of GL-g-P(AN) for the removal of Al and Mg were 3.47 and 9.66 mg/g respectively. The techniques applied in this study have shown good potential for the removal of specific pollutants from the AMD; it is however, important that the appropriate hybridization of techniques allows to remove all the pollutants and restore acceptable water quality.

Novel cost effective full scale mussel shell bioreactors for metal removal and acid neutralization.

PubMed

DiLoreto, Z A; Weber, P A; Olds, W; Pope, J; Trumm, D; Chaganti, S R; Heath, D D; Weisener, C G

2016-12-01

Acid mine drainage (AMD) impacted waters are a worldwide concern for the mining industry and countries dealing with this issue; both active and passive technologies are employed for the treatment of such waters. Mussel shell bioreactors (MSB) represent a passive technology that utilizes waste from the shellfish industry as a novel substrate. The aim of this study is to provide insight into the biogeochemical dynamics of a novel full scale MSB for AMD treatment. A combination of water quality data, targeted geochemical extractions, and metagenomic analyses were used to evaluate MSB performance. The MSB raised the effluent pH from 3.4 to 8.3 while removing up to ∼99% of the dissolved Al, and Fe and >90% Ni, Tl, and Zn. A geochemical gradient was observed progressing from oxidized to reduced conditions with depth. The redox conditions helped define the microbial consortium that consists of a specialized niche of organisms that influence elemental cycling (i.e. complex Fe and S cycling). MSB technology represents an economic and effective means of full scale, passive AMD treatment that is an attractive alternative for developing economies due to its low cost and ease of implementation. Copyright © 2016 Elsevier Ltd. All rights reserved.

River catchment responses to anthropogenic acidification in relationship with sewage effluent: An ecotoxicology screening application.

PubMed

Oberholster, P J; Botha, A-M; Hill, L; Strydom, W F

2017-12-01

Rising environmental pressures on water resources and resource quality associated with urbanisation, industrialisation, mining and agriculture are a global concern. In the current study the upper Olifants River catchment as case study was used, to show that acid mine drainage (AMD) and acid precipitation were the two most important drivers of possible acidification during a four-year study period. Over the study period 59% of the precipitation sampled was classified as acidic with a pH value below 5.6. Traces of acidification in the river system using aquatic organisms at different trophic levels were only evident in areas of AMD point sources. Data gathered from the ecotoxicology screening tools, revealed that discharge of untreated and partially treated domestic sewage from municipal sewage treatment works and informal housing partially mitigate any traces of acidification by AMD and acid precipitation in the main stem of the upper Olifants River. The outcome of the study using phytoplankton and macroinvertebrates as indicator organisms revealed that the high loads of sewage effluent might have played a major role in the neutralization of acidic surface water conditions caused by AMD and acid precipitation. Although previous multi-stage and microcosm studies confirmed the decrease in acidity and metals concentrations by municipal wastewater, the current study is the first to provide supportive evidence of this co-attenuation on catchment scale. These findings are important for integrated water resource management on catchment level, especially in river systems with a complex mixture of pollutants. Copyright © 2017 Elsevier Ltd. All rights reserved.

Investigation into the use of cement kiln dust in high density sludge (HDS) treatment of acid mine water.

PubMed

Mackie, Allison L; Walsh, Margaret E

2015-11-15

The purpose of this study was to investigate the potential to replace lime with cement kiln dust (CKD) in high density sludge (HDS) treatment of acid mine drainage (AMD). The bench-scale study used two water samples: AMD sampled from a lead-zinc mine with high concentrations of iron (Fe), zinc (Zn), and arsenic (As) (Fe/Zn-AMD) and a synthetic AMD solution (Syn-AMD) spiked with ferric sulfate (Fe2(SO4)3). Arsenic was found to be significantly reduced with CKD-HDS treatment of Fe/Zn-AMD compared to lime-HDS treatment, to concentrations below the stringent mine effluent discharge regulation of 0.10 mg As/L (i.e., 0.04 ± 0.02 mg/L). Both CKD- and lime-HDS treatment of the two AMD samples resulted in settled water Fe concentrations above the stringent discharge guideline of 0.3 mg Fe/L. CKD addition in the HDS process also resulted in high settled water turbidity, above typical discharge guidelines of 15 mg TSS/L. CKD-HDS treatment was found to result in significantly improved settled solids (i.e., sludge) quality compared to that generated in the lime-HDS process. HDS treatment with CKD resulted in 25-88% lower sludge volume indices, 2 to 9 times higher % wet solids, and 10 to 20 times higher % dry solids compared to lime addition. XRD and XPS testing indicated that CKD-HDS sludge consisted of mainly CaCO3 and SiO2 with Fe(3+) precipitates attached at particle surfaces. XRD and XPS testing of the lime-HDS generated sludge showed that it consisted of non-crystalline Fe oxides typical of sludge formed from precipitates with a high water concentration. Increased sedimentation rates were also found for CKD (1.3 cm/s) compared to lime (0.3 cm/s). The increased solids loading with CKD addition compared to lime addition in the HDS process was suggested to both promote surface complexation of metal precipitates with insoluble CKD particles and increase compression effects during Type IV sedimentation. These mechanisms collectively contributed to the reduced water content of CKD-HDS sludge. The results of this study suggest that solids loading is a significant factor in increased sludge density found with the HDS process compared to conventional lime precipitation-sedimentation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Systems-level analysis of age-related macular degeneration reveals global biomarkers and phenotype-specific functional networks

PubMed Central

2012-01-01

Background Age-related macular degeneration (AMD) is a leading cause of blindness that affects the central region of the retinal pigmented epithelium (RPE), choroid, and neural retina. Initially characterized by an accumulation of sub-RPE deposits, AMD leads to progressive retinal degeneration, and in advanced cases, irreversible vision loss. Although genetic analysis, animal models, and cell culture systems have yielded important insights into AMD, the molecular pathways underlying AMD's onset and progression remain poorly delineated. We sought to better understand the molecular underpinnings of this devastating disease by performing the first comparative transcriptome analysis of AMD and normal human donor eyes. Methods RPE-choroid and retina tissue samples were obtained from a common cohort of 31 normal, 26 AMD, and 11 potential pre-AMD human donor eyes. Transcriptome profiles were generated for macular and extramacular regions, and statistical and bioinformatic methods were employed to identify disease-associated gene signatures and functionally enriched protein association networks. Selected genes of high significance were validated using an independent donor cohort. Results We identified over 50 annotated genes enriched in cell-mediated immune responses that are globally over-expressed in RPE-choroid AMD phenotypes. Using a machine learning model and a second donor cohort, we show that the top 20 global genes are predictive of AMD clinical diagnosis. We also discovered functionally enriched gene sets in the RPE-choroid that delineate the advanced AMD phenotypes, neovascular AMD and geographic atrophy. Moreover, we identified a graded increase of transcript levels in the retina related to wound response, complement cascade, and neurogenesis that strongly correlates with decreased levels of phototransduction transcripts and increased AMD severity. Based on our findings, we assembled protein-protein interactomes that highlight functional networks likely to be involved in AMD pathogenesis. Conclusions We discovered new global biomarkers and gene expression signatures of AMD. These results are consistent with a model whereby cell-based inflammatory responses represent a central feature of AMD etiology, and depending on genetics, environment, or stochastic factors, may give rise to the advanced AMD phenotypes characterized by angiogenesis and/or cell death. Genes regulating these immunological activities, along with numerous other genes identified here, represent promising new targets for AMD-directed therapeutics and diagnostics. Please see related commentary: http://www.biomedcentral.com/1741-7015/10/21/abstract PMID:22364233

Effects of Historical Coal Mining and Drainage from Abandoned Mines on Streamflow and Water Quality in Newport and Nanticoke Creeks, Luzerne County, Pennsylvania, 1999-2000

USGS Publications Warehouse

Chaplin, Jeffrey J.; Cravotta,, Charles A.; Weitzel, Jeffrey B.; Klemow, Kenneth M.

2007-01-01

This report characterizes the effects of historical mining and abandoned mine drainage (AMD) on streamflow and water quality and evaluates potential strategies for AMD abatement in the 14-square-mile Newport Creek Basin and 7.6-square-mile Nanticoke Creek Basin. Both basins are mostly within the Northern Anthracite Coal Field and drain to the Susquehanna River in central Luzerne County, Pa. The U.S. Geological Survey (USGS), in cooperation with the Earth Conservancy, conducted an assessment from April 1999 to September 2000 that included (1) continuous stage measurement at 7 sites; (2) synoptic water-quality and flow sampling at 21 sites on June 2-4, 1999, and at 24 sites on October 7-8, 1999; and (3) periodic measurement of flow and water quality at 26 additional sites not included in the synoptic sampling effort. Stream water and surface runoff from the unmined uplands drain northward to the valley, where most of the water is intercepted and diverted into abandoned underground mines. Water that infiltrates into the mine workings becomes loaded with acidity, metals, and sulfate and later discharges as AMD at topographically low points along lower reaches of Newport Creek, Nanticoke Creek, and their tributaries. Differences among streamflows in unmined and mined areas of the watersheds indicated that (1) intermediate stream reaches within the mined area but upgradient of AMD sites generally were either dry or losing reaches, (2) ground water flowing to AMD sites could cross beneath surface-drainage divides, and (3) AMD discharging to the lower stream reaches restored volumes lost in the upstream reaches. The synoptic data for June and October 1999, along with continuous stage data during the study period, indicated flows during synoptic surveys were comparable to average values. The headwaters upstream of the mined area generally were oxygenated (dissolved oxygen range was 4.7 to 11.0 mg/L [milligrams per liter]), near-neutral (pH range was 5.8 to 7.6), and net alkaline (net alkalinity range was 2.0 to 25.0 mg/L CaCO3), with relatively low concentrations of sulfate (6.40 to 24.0 mg/L) and dissolved metals (less than 500 ug/L [micrograms per liter] of iron, manganese, and aluminum). In contrast, the AMD discharges and downstream waters were characterized by elevated concentrations of sulfate and dissolved metals that exceeded Federal and State regulatory limits. The largest AMD sources were the Susquehanna Number 7 Mine discharge entering Newport Creek near its mouth (flow range was 4.7 to 19 ft3/s [cubic feet per second]), the Truesdale Mine Discharge (Dundee Outfall) entering Nanticoke Creek about 0.5 mile upstream of Loomis Park (flow range was 0.00 to 38 ft3/s), and a mine-pit overflow entering near the midpoint of Newport Creek (flow range was 4.0 to 6.9 ft3/s). The three large discharges were poorly oxygenated (dissolved oxygen concentration range was <0.05 to 6.4 mg/L) and had elevated concentrations of sulfate (range was 710 to 890 mg/L) and low concentrations of dissolved aluminum (less than 25 ug/L), but they had distinctive concentrations of net alkalinity and dissolved iron and manganese. Effluent from the Susquehanna Number 7 Mine was near-neutral (pH range was 5.9 to 6.6) and net alkaline (net alkalinity range was 12.0 to 42.0 mg/L CaCO3) with elevated concentrations of sulfate (718 to 1,170 mg/L), dissolved iron (52,500 to 77,400 ug/L), and manganese (5,200 to 5,300 ug/L). Effluent from the Truesdale Mine also was near-neutral (pH range was 5.9 to 6.3) but had variable net alkalinity (-19.0 to 57.0 mg/L CaCO3) with elevated concentrations of sulfate (571 to 740 mg/L), dissolved iron (30,500 to 43,000 ug/L), and manganese (3,600 to 5,200 ug/L). Effluent from the mine-pit overflow in Newport Creek Basin was acidic (pH range was 4.3 to 5.0; net alkalinity range was -42 to -38 mg/L CaCO3) with elevated concentrations of sulfate (800 to 840 mg/L), iron (13,000 to 16,000 ug/L), and manganese (6,800 to 7,000 ug

Biomining of metals: how to access and exploit natural resource sustainably.

PubMed

Jerez, Carlos A

2017-09-01

Mining activities have been carried out for thousands of years and nowadays have an enormous worldwide use to obtain important metals of industrial use. These include copper, iron, gold and several others. Although modern mining companies have sustainable mining programs that include tailings management and external verifications, it is recognized that these industrial activities are responsible for a significant damage to the environment. Specially, technologies such as smelting and roasting generate very toxic emissions, including solid particles in the air, very large tailings and contribute to generate acid mine drainage (AMD) that affects humans health and all kinds of living plants, animals and microorganisms. Consequently, due to environmental restrictions, these methods are being replaced in many countries by less contaminating processes. On the other hand, the microbial solubilization of metals by bioleaching or biomining is successfully used in industrial operations, to extract several metals such as copper, gold and uranium. © 2017 The Author. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

Understanding the mobilisation of metal pollution associated with historical mining in a carboniferous upland catchment.

PubMed

Valencia-Avellan, Magaly; Slack, Rebecca; Stockdale, Anthony; Mortimer, Robert John George

2017-08-16

Point and diffuse pollution from metal mining has led to severe environmental damage worldwide. Mine drainage is a significant problem for riverine ecosystems, it is commonly acidic (AMD), but neutral mine drainage (NMD) can also occur. A representative environment for studying metal pollution from NMD is provided by carboniferous catchments characterised by a circumneutral pH and high concentrations of carbonates, supporting the formation of secondary metal-minerals as potential sinks of metals. The present study focuses on understanding the mobility of metal pollution associated with historical mining in a carboniferous upland catchment. In the uplands of the UK, river water, sediments and spoil wastes were collected over a period of fourteen months, samples were chemically analysed to identify the main metal sources and their relationships with geological and hydrological factors. Correlation tests and principal component analysis suggest that the underlying limestone bedrock controls pH and weathering reactions. Significant metal concentrations from mining activities were measured for zinc (4.3 mg l -1 ), and lead (0.3 mg l -1 ), attributed to processes such as oxidation of mined ores (e.g. sphalerite, galena) or dissolution of precipitated secondary metal-minerals (e.g. cerussite, smithsonite). Zinc and lead mobility indicated strong dependence on biogeochemistry and hydrological conditions (e.g. pH and flow) at specific locations in the catchment. Annual loads of zinc and lead (2.9 and 0.2 tonnes per year) demonstrate a significant source of both metals to downstream river reaches. Metal pollution results in a large area of catchment having a depleted chemical status with likely effects on the aquatic ecology. This study provides an improved understanding of geological and hydrological processes controlling water chemistry, which is critical to assessing metal sources and mobilization, especially in neutral mine drainage areas.

CXCR4 antagonist AMD3100 reverses the neurogenesis promoted by enriched environment and suppresses long-term seizure activity in adult rats of temporal lobe epilepsy.

PubMed

Zhou, Zhike; Liu, Tingting; Sun, Xiaoyu; Mu, Xiaopeng; Zhu, Gang; Xiao, Ting; Zhao, Mei; Zhao, Chuansheng

2017-03-30

It has been showed that enriched environment (EE) enhances the hippocampal neurogenesis and improves the cognitive impairments, accompanied by the increased expressions of stromal cell-derived factor-1 (SDF-1) in adult rats of temporal lobe epilepsy (TLE). We examined whether the enhanced neurogenesis and improved cognitive functions induced by EE following seizures were mediated by SDF-1/CXCR4 pathway. Therefore, we investigated the effects of the EE combined with CXCR4 antagonist AMD3100 on neurogenesis, cognitive functions and the long-term seizure activity in the TLE model. Adult rats were randomly assigned as control rats, rats treated with EE, rats subjected to status epilepticus (SE), post-SE rats treated with EE, AMD3100 or EE combined with AMD3100 respectively. We used immunofluorescence staining to analyze the hippocampal neurogenesis and Nissl staining to evaluate hippocampal damage. Electroencephalography was used to measure the frequency and mean duration of spontaneous seizures. Cognitive function was evaluated by Morris water maze test. EE treatment significantly, as well as improved cognitive impairments and decreased long-term seizure activity, and that these effects might be mediated through SDF-1/CXCR4 pathway during the chronic stage of TLE. Although AMD3100 reversed the effect of EE on neurogenesis, it did not abolish the cognitive improvement induced by EE following seizures. More importantly, EE combined with AMD3100 treatment significantly suppressed long-term seizure activity, which provided promising evidences to treat TLE. Copyright © 2017 Elsevier B.V. All rights reserved.

Surface-water and groundwater interactions in an extensively mined watershed, upper Schuylkill River, Pennsylvania, USA

USGS Publications Warehouse

Cravotta, Charles A.; Goode, Daniel J.; Bartles, Michael D.; Risser, Dennis W.; Galeone, Daniel G.

2014-01-01

Streams crossing underground coal mines may lose flow, while abandoned mine drainage (AMD) restores flow downstream. During 2005-12, discharge from the Pine Knot Mine Tunnel, the largest AMD source in the upper Schuylkill River Basin, had near-neutral pH and elevated concentrations of iron, manganese, and sulfate. Discharge from the tunnel responded rapidly to recharge but exhibited a prolonged recession compared to nearby streams, consistent with rapid infiltration and slow release of groundwater from the mine. Downstream of the AMD, dissolved iron was attenuated by oxidation and precipitation while dissolved CO2 degassed and pH increased. During high-flow conditions, the AMD and downstream waters exhibited decreased pH, iron, and sulfate with increased acidity that were modeled by mixing net-alkaline AMD with recharge or runoff having low ionic strength and low pH. Attenuation of dissolved iron within the river was least effective during high-flow conditions because of decreased transport time coupled with inhibitory effects of low pH on oxidation kinetics. A numerical model of groundwater flow was calibrated using groundwater levels in the Pine Knot Mine and discharge data for the Pine Knot Mine Tunnel and the West Branch Schuylkill River during a snowmelt event in January 2012. Although the calibrated model indicated substantial recharge to the mine complex took place away from streams, simulation of rapid changes in mine pool level and tunnel discharge during a high flow event in May 2012 required a source of direct recharge to the Pine Knot Mine. Such recharge produced small changes in mine pool level and rapid changes in tunnel flow rate because of extensive unsaturated storage capacity and high transmissivity within the mine complex. Thus, elimination of stream leakage could have a small effect on the annual discharge from the tunnel, but a large effect on peak discharge and associated water quality in streams.

Environmental Geochemistry and Acid Mine Drainage Evaluation of an Abandoned Coal Waste Pile at the Alborz-Sharghi Coal Washing Plant, NE Iran

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jodeiri Shokri, Behshad, E-mail: b.jodeiri@hut.ac.ir; Doulati Ardejani, Faramarz; Ramazi, Hamidreza

In this paper, an abandoned waste coal pile, which is resulted from Alborz-Sharghi coal washing plant, NE of Iran was mineralogically and geochemically characterized to evaluate pyrite oxidation, acid mine drainage (AMD) generation, and trace element mobility. After digging ten trenches and vertical sampling, a quantitative method including the atomic absorption test, and the quality-based methods including optical study were carried out for determination of pyrite fractions in the waste pile. The geochemical results revealed that the fraction of remaining pyrite increased with depth, indicating that pyrite oxidation is limited to the shallower depths of the pile which were confirmedmore » by variations of sulfate, pH, EC, and carbonate with depth of the pile. To evaluate the trend of trace elements and mineralogical constituents of the waste particles, the samples were analyzed by using XRD, ICP-MS, and ICP-OES methods. The results showed the secondary and neutralizing minerals comprising gypsum have been formed below the oxidation zone. Besides, positive values of net neutralization potential indicated that AMD generation has not taken in the waste pile. In addition, variations of trace elements with depth reveal that Pb and Zn exhibited increasing trends from pile surface toward the bottom sampling trenches while another of them such as Cu and Ni had decreasing trends with increasing depth of the waste pile.« less

Preparation of metal-resistant immobilized sulfate reducing bacteria beads for acid mine drainage treatment.

PubMed

Zhang, Mingliang; Wang, Haixia; Han, Xuemei

2016-07-01

Novel immobilized sulfate-reducing bacteria (SRB) beads were prepared for the treatment of synthetic acid mine drainage (AMD) containing high concentrations of Fe, Cu, Cd and Zn using up-flow anaerobic packed-bed bioreactor. The tolerance of immobilized SRB beads to heavy metals was significantly enhanced compared with that of suspended SRB. High removal efficiencies of sulfate (61-88%) and heavy metals (>99.9%) as well as slightly alkaline effluent pH (7.3-7.8) were achieved when the bioreactor was fed with acidic influent (pH 2.7) containing high concentrations of multiple metals (Fe 469 mg/L, Cu 88 mg/L, Cd 92 mg/L and Zn 128 mg/L), which showed that the bioreactor filled with immobilized SRB beads had tolerance to AMD containing high concentrations of heavy metals. Partially decomposed maize straw was a carbon source and stabilizing agent in the initial phase of bioreactor operation but later had to be supplemented by a soluble carbon source such as sodium lactate. The microbial community in the bioreactor was characterized by denaturing gradient gel electrophoresis (DGGE) and sequencing of partial 16S rDNA genes. Synergistic interaction between SRB (Desulfovibrio desulfuricans) and co-existing fermentative bacteria could be the key factor for the utilization of complex organic substrate (maize straw) as carbon and nutrients source for sulfate reduction. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of iron on arsenic speciation and redox chemistry in acid mine water

USGS Publications Warehouse

Bednar, A.J.; Garbarino, J.R.; Ranville, J.F.; Wildeman, T.R.

2005-01-01

Concern about arsenic is increasing throughout the world, including areas of the United States. Elevated levels of arsenic above current drinking-water regulations in ground and surface water can be the result of purely natural phenomena, but often are due to anthropogenic activities, such as mining and agriculture. The current study correlates arsenic speciation in acid mine drainage and mining-influenced water with the important water-chemistry properties Eh, pH, and iron(III) concentration. The results show that arsenic speciation is generally in equilibrium with iron chemistry in low pH AMD, which is often not the case in other natural-water matrices. High pH mine waters and groundwater do not always hold to the redox predictions as well as low pH AMD samples. The oxidation and precipitation of oxyhydroxides deplete iron from some systems, and also affect arsenite and arsenate concentrations through sorption processes. ?? 2004 Elsevier B.V. All rights reserved.

Unrealistic representations of "the self": A cognitive neuroscience assessment of anosognosia for memory deficit.

PubMed

Berlingeri, Manuela; Ravasio, Alessandra; Cranna, Silvia; Basilico, Stefania; Sberna, Maurizio; Bottini, Gabriella; Paulesu, Eraldo

2015-12-01

Three cognitive components may play a crucial role in both memory awareness and in anosognosia for memory deficit (AMD): (1) a personal data base (PDB), i.e., a memory store that contains "semantic" representations about the self, (2) monitoring processes (MPs) and (3) an explicit evaluation system (EES), or comparator, that assesses and binds the representations stored in the PDB with information obtained from the environment. We compared both the behavior and the functional connectivity (as assessed by resting-state fMRI) of AMD patients with aware patients and healthy controls. We found that AMD is associated with an impoverished PDB, while MPs are necessary to successfully update the PDB. AMD was associated with reduced functional connectivity within both the default-mode network and in a network that includes the left lateral temporal cortex, the hippocampus and the insula. The reduced connectivity between the hippocampus and the insular cortex was correlated with AMD severity. Copyright © 2015 Elsevier Inc. All rights reserved.

Reuse of Treated Internal or External Wastewaters in the Cooling Systems of Coal-Based Thermoelectric Power Plants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Radisav Vidic; David Dzombak; Ming-Kai Hsieh

2009-06-30

This study evaluated the feasibility of using three impaired waters - secondary treated municipal wastewater, passively treated abandoned mine drainage (AMD), and effluent from ash sedimentation ponds at power plants - for use as makeup water in recirculating cooling water systems at thermoelectric power plants. The evaluation included assessment of water availability based on proximity and relevant regulations as well as feasibility of managing cooling water quality with traditional chemical management schemes. Options for chemical treatment to prevent corrosion, scaling, and biofouling were identified through review of current practices, and were tested at bench and pilot-scale. Secondary treated wastewater ismore » the most widely available impaired water that can serve as a reliable source of cooling water makeup. There are no federal regulations specifically related to impaired water reuse but a number of states have introduced regulations with primary focus on water aerosol 'drift' emitted from cooling towers, which has the potential to contain elevated concentrations of chemicals and microorganisms and may pose health risk to the public. It was determined that corrosion, scaling, and biofouling can be controlled adequately in cooling systems using secondary treated municipal wastewater at 4-6 cycles of concentration. The high concentration of dissolved solids in treated AMD rendered difficulties in scaling inhibition and requires more comprehensive pretreatment and scaling controls. Addition of appropriate chemicals can adequately control corrosion, scaling and biological growth in ash transport water, which typically has the best water quality among the three waters evaluated in this study. The high TDS in the blowdown from pilot-scale testing units with both passively treated mine drainage and secondary treated municipal wastewater and the high sulfate concentration in the mine drainage blowdown water were identified as the main challenges for blowdown disposal. Membrane treatment (nanofiltration or reverse osmosis) can be employed to reduce TDS and sulfate concentrations to acceptable levels for reuse of the blowdown in the cooling systems as makeup water.« less

Groundwater hydrogeochemical characteristics in rehabilitated coalmine spoils

NASA Astrophysics Data System (ADS)

Gomo, M.; Masemola, E.

2016-04-01

The investigation aims to identify and describe hydrogeochemical processes controlling the evolution of groundwater chemistry in rehabilitated coalmine spoils and their overall influence on groundwater quality at a study area located in the Karoo basin of South Africa. A good understanding of the processes that controls the evolution of the mine water quality is vital for the planning, application and management of post-mining remedial actions. The study utilises scatter plots, statistical analysis, PHREEQC hydrogeochemical modelling, stoichiometric reaction ratios analysis, and the expanded Durov diagram as complimentary tools to interpret the groundwater chemistry data collected from monitoring boreholes from 1995 to 2014. Measured pH ranging between 6-8 and arithmetic mean of 7.32 shows that the groundwater system is characterised by circumneutral hydrogeochemical conditions period. Comparison of measured groundwater ion concentrations to theoretical reaction stoichiometry identifies Dolomite-Acid Mine Drainage (AMD) neutralisation as the main hydrogeochemical process controlling the evolution of the groundwater chemistry. Hydrogeochemical modelling shows that, the groundwater has temporal variations of calcite and dolomite saturation indices characterised by alternating cycles of over-saturation and under-saturation that is driven by the release of sulphate, calcium and magnesium ions from the carbonate-AMD neutralization process. Arithmetic mean concentrations of sulphate, calcium and magnesium are in the order of 762 mg/L, 141 mg/L and 108 mg/L. Calcium and magnesium ions contribute to very hard groundwater quality conditions. Classification based on total dissolved solids (TDS), shows the circumneutral water is of poor to unacceptable quality for drinking purposes. Despite its ability to prevent AMD formation and leaching of metals, the dolomite-AMD neutralisation process can still lead to problems of elevated TDS and hardness which mines should be aware of when developing water quality management plans.

Nitrifier Gene Abundance and Diversity in Sediments Impacted by Acid Mine Drainage

PubMed Central

Ramanathan, Bhargavi; Boddicker, Andrew M.; Roane, Timberley M.; Mosier, Annika C.

2017-01-01

Extremely acidic and metal-rich acid mine drainage (AMD) waters can have severe toxicological effects on aquatic ecosystems. AMD has been shown to completely halt nitrification, which plays an important role in transferring nitrogen to higher organisms and in mitigating nitrogen pollution. We evaluated the gene abundance and diversity of nitrifying microbes in AMD-impacted sediments: ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB), and nitrite-oxidizing bacteria (NOB). Samples were collected from the Iron Springs Mining District (Ophir, CO, United States) during early and late summer in 2013 and 2014. Many of the sites were characterized by low pH (<5) and high metal concentrations. Sequence analyses revealed AOA genes related to Nitrososphaera, Nitrosotalea, and Nitrosoarchaeum; AOB genes related to Nitrosomonas and Nitrosospira; and NOB genes related to Nitrospira. The overall abundance of AOA, AOB and NOB was examined using quantitative PCR (qPCR) amplification of the amoA and nxrB functional genes and 16S rRNA genes. Gene copy numbers ranged from 3.2 × 104 – 4.9 × 107 archaeal amoA copies ∗ μg DNA-1, 1.5 × 103 – 5.3 × 105 AOB 16S rRNA copies ∗ μg DNA-1, and 1.3 × 106 – 7.7 × 107 Nitrospira nxrB copies ∗ μg DNA-1. Overall, Nitrospira nxrB genes were found to be more abundant than AOB 16S rRNA and archaeal amoA genes in most of the sample sites across 2013 and 2014. AOB 16S rRNA and Nitrospira nxrB genes were quantified in sediments with pH as low as 3.2, and AOA amoA genes were quantified in sediments as low as 3.5. Though pH varied across all sites (pH 3.2–8.3), pH was not strongly correlated to the overall community structure or relative abundance of individual OTUs for any gene (based on CCA and Spearman correlations). pH was positivity correlated to the total abundance (qPCR) of AOB 16S rRNA genes, but not for any other genes. Metals were not correlated to the overall nitrifier community composition or abundance, but were correlated to the relative abundances of several individual OTUs. These findings extend our understanding of the distribution of nitrifying microbes in AMD-impacted systems and provide a platform for further research. PMID:29209281

Mineral-microorganism interactions in Acid Mine Drainage environments: preliminary results

NASA Astrophysics Data System (ADS)

Carbone, Cristina; Zotti, Mirca; Pozzolini, Marina; Giovine, Marco; Di Piazza, Simone; Mariotti, Mauro; Lucchetti, Gabriella

2014-05-01

Minerals play a key role in controlling the mobility and distribution of metals and metalloids of environmental concern in supergenic environments. These are involved in a variety of processes, spanning the alteration of primary minerals to the formation of secondary authigenic phases and can represent a source or a trap for Potentially Ecotoxic Elements (PTEs). Soil, sediments, and waters heavily polluted with PTEs through AMD processes are a reservoir of a unusual bacteria and fungi well adapted to these toxic environments. Classical studies of biotic weathering have mainly focused on water-mineral interaction and on the ability of microorganism to influence the soil solution chemical composition. In this work, we analyzed two different representative ochreous and greenish-blue AMD colloidal precipitates in order to i) characterize the biota population present in these colloidal minerals and ii) verify the bioaccumulation of PTEs into the fungi and the potential impact of bacteria in the geochemistry of the system. The samples are composed by nanocrystalline goethite which contains high amounts of Fe, Cu, Zn, Pb, and Ni and woodwardite that is characterized by Cu, Zn, Ni, Y, and Ce. These precipitates were examined in order to evaluate the presence of fungal strains and to extract bacteria DNA. The preliminary results of fungi characterization show an interesting and selected mycobiota able to survive under unfavourable environmental conditions. A significant number of fungal strains was isolated in pure culture. Most of them belong to the genus Mucor and Penicillium. It is worth noting the presence of Trametes versicolor, a macrofungal lignicolous species already known for heavy metal biosorption capability from aqueous solution (Gülay et al 2003). The same colloidal precipitates have been processed to extract bacteria DNA, using a specific procedure developed for DNA extraction from sediments. The results gave a good yield of nucleic acids and the positive PCR amplification of 16S rDNA accomplished the first step for future metagenomic analysis. Gülay B., Sema B., M. Yakup A.. 2003 Biosorption of heavy metal ions on immobilized white-rot fungus Trametes versicolor. Journal of Hazardous Materials B101 (2003) 285-300

Lab-scale study on the application of In-Adit-Sulfate-Reducing System for AMD control.

PubMed

Ji, S W; Kim, S J

2008-12-30

In a study of the 29 operating passive systems for acid mine drainage (AMD) treatment, 19 systems showed various performance problems. Some systems showed very low efficiency even without visible leakage or overflow. Though systems show fairly good efficiency in metal removal (mainly iron) and pH control, sulfate removal rates were very low which indicates the possibility of very poor sulfate reductions by Sulfate Reducing Bacteria (SRB). As an alternative method, In-Adit-Sulfate-Reducing System (IASRS), the method of placing the SAPS inside the adit, to have temperature constant at about 15 degrees C, was suggested. Lab-scale model experiments of IASRS were carried out. The models 1 and 2 were run at 15 degrees C and 25 degrees C, respectively. The model 1 contained about a half of COD in the beginning of the operation than that of model 2. Metal removal ratios were higher than 90% in both systems. Both systems showed the sulfate removal ratios of 23% and 27%, respectively, which were still considerably low, even though higher than those of presently operating systems. However, since the synthetic AMD used was very low in pH (2.8) and very high in sulfate concentration, if some suggested modifications were applied to the standard design, it is presumed that the sulfate removal ratio would have increased.

Employing OpenCL to Accelerate Ab Initio Calculations on Graphics Processing Units.

PubMed

Kussmann, Jörg; Ochsenfeld, Christian

2017-06-13

We present an extension of our graphics processing units (GPU)-accelerated quantum chemistry package to employ OpenCL compute kernels, which can be executed on a wide range of computing devices like CPUs, Intel Xeon Phi, and AMD GPUs. Here, we focus on the use of AMD GPUs and discuss differences as compared to CUDA-based calculations on NVIDIA GPUs. First illustrative timings are presented for hybrid density functional theory calculations using serial as well as parallel compute environments. The results show that AMD GPUs are as fast or faster than comparable NVIDIA GPUs and provide a viable alternative for quantum chemical applications.

Diatom diversity and response in metal-polluted river environment: preliminary reports from Gromolo Torrent (Liguria, Italy)

NASA Astrophysics Data System (ADS)

Capello, Marco; Tolotti, Raffaella; Bernabè, Dimitri; Carbone, Cristina; Consani, Sirio; Vagge, Greta; Cutroneo, Laura

2016-04-01

Mineral content and physico-chemical properties of the freshwaters are the main factors affecting both algal assemblages and distributions, while presence of dissolved silicon, low water conductivity, and rocky-mountain habitats host benthic diatom assemblages of high species richness. It is shown that diatoms are sensible to the freshwater acidification (used as pH indicators in acid waters), environmental and climate changes, river organic load, and heavy metal water pollution. For this characteristic, diatoms are among the major biological markers for a variety of environmental and stratigraphic applications. In particular, qualitative and quantitative analyses (assemblage analyses) together with biotic indices as well as morphological and ultrastructure parameterisation provide tools for detailed environmental control and paleo-environmental reconstructions. Severe environmental problems are typically caused by "abandoned mine" and are consequences of the cessation of the mining activity with a lack in infrastructure maintenance. The mine waters which flow into the Gromolo Torrent are almost acidic (pH varying from 2.4 to 5) and enriched in heavy metals and SO42-. This pollution is caused by Acid Mine Drainage (AMD) processes that interest the Libiola mining area, known as a typical example of active AMD processes. The aim of this work is: 1) to characterise the local benthic diatom assemblages along the acidic mine effluents that discharge from Libiola mine, the entire Gromolo torrent course, and in the marine area off the torrent mouth; 2) to identify the main diatom biomarker taxa; 3) to highlight striking situations of equilibrium-disequilibrium in the algal communities, and 4) to point out types and frequency of some teratologies affecting specific diatom taxa as a response to environmental stressors (such as metal-metalloid enrichment). A total of 17 diatom samples was collected and examined, including some marine samples. Diatoms were collected in the riverbed from the hard surface of selected cobblestone by scraping. In laboratory all the samples were washed (by digestion with hydrogen peroxide) and mounted according to the protocol used by the DISTAV Laboratories (University of Genoa). Identification and enumeration of diatom valves was performed using an LM Reichert Jung-Polyvar microscope with 1000x oil-immersion lens. Moreover, a representative subsample of each preparation was observed using SEM images providing an interesting iconographic dataset. Preliminary results show that diatom assemblages are characteristic (in both quality and quantity) in the three different environmental conditions highlighted: a) in AMD environment diatoms are quantitatively scarcely, represented by both typically pioneer and highly tolerant species; b) in the Gromolo torrent diatoms are well represented with fairly well-structured communities, but present specific types and different frequencies in teratological frustula, whereas c) in marine environment they are very poorly represented.

GIS-based groundwater vulnerability modelling: A case study of the Witbank, Ermelo and Highveld Coalfields in South Africa

NASA Astrophysics Data System (ADS)

Sakala, E.; Fourie, F.; Gomo, M.; Coetzee, H.

2018-01-01

In the last 20 years, the popular mineral systems approach has been used successfully for the exploration of various mineral commodities at various scales owing to its scientific soundness, cost effectiveness and simplicity in mapping the critical processes required for the formation of deposits. In the present study this approach was modified for the assessment of groundwater vulnerability. In terms of the modified approach, water drives the pollution migration processes, with various analogies having been derived from the mineral systems approach. The modified approach is illustrated here by the discussion of a case study of acid mine drainage (AMD) pollution in the Witbank, Ermelo and Highveld coalfields of the Mpumalanga and KwaZulu-Natal Provinces in South Africa. Many AMD cases have been reported in these provinces in recent years and are a cause of concern for local municipalities, mining and environmental agencies. In the Witbank, Ermelo and Highveld coalfields, several areas have been mined out while mining has not yet started in others, hence the need to identify groundwater regions prone to AMD pollution in order to avoid further impacts on the groundwater resources. A knowledge-based fuzzy expert system was built using vulnerability factors (energy sources, ligands sources, pollutant sources, transportation pathways and traps) to generate a groundwater vulnerability model of the coalfields. Highly vulnerable areas were identified in Witbank coalfield and the eastern part of the Ermelo coalfield which are characterised by the presence of AMD sources, good subsurface transport coupled with poor AMD pollution trapping properties. The results from the analysis indicate significant correlations between model values and both groundwater sulphate concentrations as well as pH. This shows that the proposed approach can indeed be used as an alternative to traditional methods of groundwater vulnerability assessment. The methodology only considers the AMD pollution attenuation and migration at a regional scale and does not account for local-scale sources of pollution and attenuation. Further research to refine the approach may include the incorporation of groundwater flow direction, rock-pollution reaction time, and temporal datasets for the future prediction of groundwater vulnerability. The approach may be applied to other coalfields to assess its robustness to changing hydrogeological conditions.

Depth-dependent geochemical and microbiological gradients in Fe(III) deposits resulting from coal mine-derived acid mine drainage

PubMed Central

Brantner, Justin S.; Haake, Zachary J.; Burwick, John E.; Menge, Christopher M.; Hotchkiss, Shane T.; Senko, John M.

2014-01-01

We evaluated the depth-dependent geochemistry and microbiology of sediments that have developed via the microbially-mediated oxidation of Fe(II) dissolved in acid mine drainage (AMD), giving rise to a 8–10 cm deep “iron mound” that is composed primarily of Fe(III) (hydr)oxide phases. Chemical analyses of iron mound sediments indicated a zone of maximal Fe(III) reducing bacterial activity at a depth of approximately 2.5 cm despite the availability of dissolved O2 at this depth. Subsequently, Fe(II) was depleted at depths within the iron mound sediments that did not contain abundant O2. Evaluations of microbial communities at 1 cm depth intervals within the iron mound sediments using “next generation” nucleic acid sequencing approaches revealed an abundance of phylotypes attributable to acidophilic Fe(II) oxidizing Betaproteobacteria and the chloroplasts of photosynthetic microeukaryotic organisms in the upper 4 cm of the iron mound sediments. While we observed a depth-dependent transition in microbial community structure within the iron mound sediments, phylotypes attributable to Gammaproteobacterial lineages capable of both Fe(II) oxidation and Fe(III) reduction were abundant in sequence libraries (comprising ≥20% of sequences) from all depths. Similarly, abundances of total cells and culturable Fe(II) oxidizing bacteria were uniform throughout the iron mound sediments. Our results indicate that O2 and Fe(III) reduction co-occur in AMD-induced iron mound sediments, but that Fe(II)-oxidizing activity may be sustained in regions of the sediments that are depleted in O2. PMID:24860562

Acute toxicity of an acid mine drainage mixing zone to juvenile bluegill and largemouth bass

USGS Publications Warehouse

Henry, T.B.; Irwin, E.R.; Grizzle, J.M.; Wildhaber, M.L.; Brumbaugh, W.G.

1999-01-01

The toxicity of an acid mixing zone produced at the confluence of a stream that was contaminated by acid mine drainage (AMD) and a pH-neutral stream was investigated in toxicity tests with juvenile bluegill Lepomis macrochirus and largemouth bass Micropterus salmoides. Fish mortalities in instream cages located in the mixing zone, below the mixing zone, and upstream in both tributaries were compared to determine relative toxicity at each site. In all tests and for both species, significantly higher mortality was observed in the mixing zone than at any other location, including the acid stream, which had lower pH (2.9-4.3). The mixing zone was defined chemically by rapid precipitation of dissolved aluminum and iron, which arrived from the low-pH stream, and by the presence of white precipitates, which were attached to the substratum and which extended below the confluence. Possible seasonal changes in mixing zone toxicity were investigated by conducting field tests with bluegill in June, July, and August 1996 and in January 1997 and by conducting field tests with largemouth bass in April and May 1997. Toxicity was not significantly different at the extremes of temperature, pH, and metal concentration that occurred in June and July, as compared with January. Toxicity was significantly lower in August; however, elevated stream discharge during the August test may have disturbed mixing zone characteristics. High toxicity in AMD mixing zones may lower the survival of fishes in streams, reduce available habitat, and impede movements of migratory fish.

Nature and nurture- genes and environment- predict onset and progression of macular degeneration.

PubMed

Sobrin, Lucia; Seddon, Johanna M

2014-05-01

Age-related macular degeneration (AMD) is a common cause of irreversible visual loss and the disease burden is rising world-wide as the population ages. Both environmental and genetic factors contribute to the development of this disease. Among environmental factors, smoking, obesity and dietary factors including antioxidants and dietary fat intake influence onset and progression of AMD. There are also several lines of evidence that link cardiovascular, immune and inflammatory biomarkers to AMD. The genetic etiology of AMD has been and continues to be an intense and fruitful area of investigation. Genome-wide association studies have revealed numerous common variants associated with AMD and sequencing is increasing our knowledge of how rare genetic variants strongly impact disease. Evidence for interactions between environmental, therapeutic and genetic factors is emerging and elucidating the mechanisms of this interplay remains a major challenge in the field. Genotype-phenotype associations are evolving. The knowledge of non-genetic, modifiable risk factors along with information about heritability and genetic risk variants for this disease acquired over the past 25 years have greatly improved patient management and our ability to predict which patients will develop or progress to advanced forms of AMD. Personalized medicine and individualized prevention and treatment strategies may become a reality in the near future. Copyright © 2014. Published by Elsevier Ltd.

Effects of mining activities on evolution of water chemistry in coal-bearing aquifers in karst region of Midwestern Guizhou, China: evidences from δ13C of dissolved inorganic carbon and δ34S of sulfate.

PubMed

Li, Qingguang; Wu, Pan; Zha, Xuefang; Li, Xuexian; Wu, Linna; Gu, Shangyi

2018-04-24

The generation of acid mine drainage (AMD) may accelerate watershed erosion and promote the migration of heavy metals, then threaten local ecosystems such as aquatic life and even human health. Previous studies have focused primarily on influence of AMD in surface environment. In order to reveal the acidizing processes in karst high-sulfur coalfield in Southwest China, this study, by contrast, focused on the hydrogeochemical evolution process and acidification mechanism of mine water in Zhijin coalfield, western Guizhou Province. The oxidation of pyrite and other sulfides induced strong acidification of mine water according to the water chemical analysis. As a result, a series of geochemical processes such as dissolution of carbonates and silicates, hydrolysis of metal ions, and degassing of CO 2 complicated water chemical evolution. The dissolution of silicates controlled the chemical composition of mine water, but more carbonates might be dissolved during the acidification of mine water. The sources of sulfate are quite different in water samples collected from the two selected mine. According to sulfur isotope analysis, the dissolution of gypsum is the primary source of sulfate in samples from Hongfa mine, whereas sulfide oxidation contributed a large amount of sulfate to the mine water in Fenghuangshan mine. The dissolution of carbonates should be an important source of DIC in mine water and CO 2 originating from organic mineralization might also have a certain contribution. This study elucidated the groundwater chemical evolution processes in high-sulfur coal-bearing strata and provided a foundation for further study of carbonates erosion and carbon emission during acidification of mine water.

Criminal enforcement of the Clean Water Act in the coal fields: United States vs. law and beyond

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scott, P.B.; Bryant, S.B.

Criminal prosecution has become an integral part of federal enforcement of this nation's environmental laws. In fiscal year 1991, the United States Environmental Protection Agency (EPA) reported record criminal fines. From 1987 to 1991, prison time and criminal fines imposed in cases investigated by EPA more than quadrupled. Many commentators have noted, often with chagrin, the trend toward more frequent criminal prosecution. The reasons for this upsurge are both straightforward and compelling. One is society's recognition that those who illegally despoil our environment for financial gain must be severely punished. The second and more compelling reason for prosecution is themore » dramatic deterrent effect that these cases can have. While civil fines undoubtedly affect corporate behavior, too often they can be dismissed as just another cost of doing business. Law stands for the proposition that a property owner's responsibilities under the Clean Water Act (CWA) are defined by the statute. There are no [open quotes]inherent[close quotes] preconditions to those responsibilities such as original production of the pollutants discharged or absolute knowledge of the discharge before purchase of the property. The important of Law for the CWA is that the statute's terms will be given their full force-even in criminal prosecutions. What does this mean for CWA enforcement in the coal fields Regulators and prosecutors now have the answers to questions that have plagued them for years. First, it is now beyond dispute that surface land owners are liable under the CWA for Acid Mine Drainage (AMD) discharged from point sources on their property. This is so even if the AMD is generated from abandoned sites or from subsurface property or other surface property in which the landowners have no interest.« less

Bacterial Formation of As(V) and As(III) Ferric Oxyhydroxides in Acid Mine Drainage.

NASA Astrophysics Data System (ADS)

Morin, G.; Juillot, F.; Lebrun, S.; Casiot, C.; Elbaz-Poulichet, F.; Bruneel, O.; Personne, J.; Leblanc, M.; Ildefonse, P.; Calas, G.

2002-12-01

The oxidation of dissolved Fe(II) which is often promoted by acidophilic bacteria in acid mine drainage (AMD) and some hot springs, leads to the precipitation of Fe(III) oxy-hydroxides which incorporate toxic elements within their structure or adsorb them at their surface, thus limiting their mobility. In such complex natural systems, synchrotron-based techniques as X-ray absorption spectroscopy offer the opportunity to monitor surface/solution interactions as well as redox changes affecting the mobility and toxicity of trace elements as arsenic. Spatial and seasonal variations of the (bio-) oxidation of Fe(II) and As(III), and the subsequent precipitation of As-Fe gels, were followed by XANES, XRD, and SEM along the CarnoulŠs AMD (Gard, France). Chemical and mineralogical data collected on sediments, stromatolite, and bioassay samples showed that some indigenous bacteria living in the As-rich CarnoulŠs water ([As] = up to 350 mg.l-1) play an important role in the nature and composition of the solid phases that sequester arsenic at the site. The formation of nano-crystalline and amorphous As(III) ferric oxy-hydroxides has been related to the presence of bacteria able to oxidize Fe(II) but not As(III), which are only present in winter in the upstream area. A rare ferric arsenite sulfate oxy-hydroxide mineral was discovered in this context. Other types of bacteria, occurring in the downstream area whatever the season, are able to catalyze As(III) to As(V) oxidation and, provided that enough Fe(II) oxidizes, promote the formation of amorphous As(V) rich ferric oxy-hydroxides. These bacterially mediated reactions significantly reduce the concentration of dissolved As(III), which is more toxic and mobile than As(V), and might thus be helpful for designing As-removal processes. This work was supported by the French PEVS and ACI Ecologie Quantitative Programs and the PIRAMID EC program. ?Deceased, 26 October 1999 Juillot F., Ildefonse Ph., Morin G., Calas G., De Kersabiec A.M. and Benedetti M. Applied Geochemistry 8, 1031-1048 (1999). Morin G., Lecocq D., Juillot F., Ildefonse Ph., Calas Bull. Soc. Géol. Fr. 173, 281-291 (2002). Morin G., Juillot F., Casiot C., Bruneel O., Personné J-C., Elbaz-Poulichet F., Leblanc M., Ildefonse P. and Calas G. Environ. Sci. Technol (in review.)

Effect of ambient light and age-related macular degeneration on precision walking.

PubMed

Alexander, M Scott; Lajoie, Kim; Neima, David R; Strath, Robert A; Robinovitch, Stephen N; Marigold, Daniel S

2014-08-01

To determine how age-related macular degeneration (AMD) and changes in ambient light affect the control of foot placement while walking. Ten older adults with AMD and 11 normal-sighted controls performed a precision walking task under normal (∼600 lx), dim (∼0.7 lx), and after a sudden reduction (∼600 to 0.7 lx) of light. The precision walking task involved subjects walking and stepping to the center of a series of irregularly spaced, low-contrast targets. Habitual visual acuity and contrast sensitivity and visual field function were also assessed. There were no differences between groups when performing the walking task in normal light (p > 0.05). In reduced lighting, older adults with AMD were less accurate and more variable when stepping across the targets compared to controls (p < 0.05). A sudden reduction of light proved the most challenging for this population. In the AMD group, contrast sensitivity and visual acuity were not significantly correlated with walking performance. Visual field thresholds in the AMD group were only associated with greater foot placement error and variability in the dim light walking condition (r = -0.69 to -0.87, p < 0.05). While walking performance is similar between groups in normal light, poor ambient lighting results in decreased foot placement accuracy in older adults with AMD. Improper foot placement while walking can lead to a fall and possible injury. Thus, to improve the mobility of those with AMD, strategies to enhance the environment in reduced lighting situations are necessary.

[Perception of objects and scenes in age-related macular degeneration].

PubMed

Tran, T H C; Boucart, M

2012-01-01

Vision related quality of life questionnaires suggest that patients with AMD exhibit difficulties in finding objects and in mobility. In the natural environment, objects seldom appear in isolation. They appear in a spatial context which may obscure them in part or place obstacles in the patient's path. Furthermore, the luminance of a natural scene varies as a function of the hour of the day and the light source, which can alter perception. This study aims to evaluate recognition of objects and natural scenes by patients with AMD, by using photographs of such scenes. Studies demonstrate that AMD patients are able to categorize scenes as nature scenes or urban scenes and to discriminate indoor from outdoor scenes with a high degree of precision. They detect objects better in isolation, in color, or against a white background than in their natural contexts. These patients encounter more difficulties than normally sighted individuals in detecting objects in a low-contrast, black-and-white scene. These results may have implications for rehabilitation, for layout of texts and magazines for the reading-impaired and for the rearrangement of the spatial environment of older AMD patients in order to facilitate mobility, finding objects and reducing the risk of falls. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

Treatment of acidic sulfate-containing wastewater using revolving algae biofilm reactors: Sulfur removal performance and microbial community characterization.

PubMed

Zhou, Haoyuan; Sheng, Yanqing; Zhao, Xuefei; Gross, Martin; Wen, Zhiyou

2018-05-18

Industries such as mining operations are facing challenges of treating sulfur-containing wastewater such as acid mine drainage (AMD) generated in their plant. The aim of this work is to evaluate the use of a revolving algal biofilm (RAB) reactor to treat AMD with low pH (3.5-4) and high sulfate content (1-4 g/L). The RAB reactors resulted in sulfate removal efficiency up to 46% and removal rate up to 0.56 g/L-day, much higher than those obtained in suspension algal culture. The high-throughput sequencing revealed that the RAB reactor contained diverse cyanobacteria, green algae, diatoms, and acid reducing bacteria that contribute the sulfate removal through various mechanisms. The RAB reactors also showed a superior performance of COD, ammonia and phosphorus removal. Collectively, the study demonstrated that RAB-based process is an effective method to remove sulfate in wastewater with small footprint and can be potentially installed in municipal or industrial wastewater treatment facilities. Copyright © 2018 Elsevier Ltd. All rights reserved.

Performance of two differently designed permeable reactive barriers with sulfate and zinc solutions.

PubMed

Pérez, Norma; Schwarz, Alex O; Barahona, Esteban; Sanhueza, Pamela; Diaz, Isabel; Urrutia, Homero

2018-06-18

For the first time, this laboratory-scale study evaluates the feasibility of incorporating diffusive exchange in permeable reactive barriers. In order to do this, the performance of two permeable reactive barriers (PRB) with different internal substrate arrangements were compared during the administration of a sulfate solution without metals (for 163 days) and with metals (for 60 days), simulating groundwater contaminated with acid mine drainage (AMD). In order to simulate a traditional PRB, a homogeneous distribution was implemented in the first reactor and the other PRB reactor utilized diffusion-active technology (DAPRB). In the DAPRB, the distribution of the reactive material was interspersed with the conductive material. The measurements in the internal ports showed that transverse gradients of sulfide formed in the DAPRB, causing the diffusion of sulfide from the substrate toward the layer interface, which is where the sulfide reacts by forming complexes with the metal. The DAPRB prevents the microorganisms from direct contact with AMD. This protection caused greater activity (sulfide production). Copyright © 2018 Elsevier B.V. All rights reserved.

Evaluation of mine seals constructed in 1967 at Elkins, Randolph County, West Virginia. Report of investigations/1984

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adams, L.M.; Lipscomb, J.R.

1984-01-01

In 1980, the Bureau of Mines surveyed a group of mine seals in Randolph County, WV, to evaluate their effectiveness for reducing toxic pollutants in mine water discharges. The survey focused on 11 block wet mine seals, but mine seals of several other types were also examined. The seals were designed to prevent air from entering the mine portals while allowing mine water to flow out. It was believed that by preventing air from entering inactive or abandoned mines, the formation of toxic pollutants and acid mine drainage (AMD) could be reduced.

The role of remediation, natural alkalinity sources and physical stream parameters in stream recovery.

PubMed

Kruse, Natalie A; DeRose, Lisa; Korenowsky, Rebekah; Bowman, Jennifer R; Lopez, Dina; Johnson, Kelly; Rankin, Edward

2013-10-15

Acid mine drainage (AMD) negatively impacts not only stream chemistry, but also aquatic biology. The ultimate goal of AMD treatment is restoration of the biological community, but that goal is rarely explicit in treatment system design. Hewett Fork in Raccoon Creek Watershed, Ohio, has been impacted by historic coal mining and has been treated with a calcium oxide doser in the headwaters of the watershed since 2004. All of the acidic inputs are isolated to a 1.5 km stretch of stream in the headwaters of the Hewett Fork watershed. The macroinvertebrate and fish communities have begun to recover and it is possible to distinguish three zones downstream of the doser: an impaired zone, a transition zone and a recovered zone. Alkalinity from both the doser and natural sources and physical stream parameters play a role in stream restoration. In Hewett Fork, natural alkaline additions downstream are higher than those from the doser. Both, alkaline additions and stream velocity drive sediment and metal deposition. Metal deposition occurs in several patterns; aluminum tends to deposit in regions of low stream velocity, while iron tends to deposit once sufficient alkalinity is added to the system downstream of mining inputs. The majority of metal deposition occurs upstream of the recovered zone. Both the physical stream parameters and natural alkalinity sources influence biological recovery in treated AMD streams and should be considered in remediation plans. Copyright © 2013 Elsevier Ltd. All rights reserved.

N- and O- ligand doped mesoporous silica-chitosan hybrid beads for the efficient, sustainable and selective recovery of rare earth elements (REE) from acid mine drainage (AMD): Understanding the significance of physical modification and conditioning of the polymer.

PubMed

Ramasamy, Deepika Lakshmi; Puhakka, Ville; Iftekhar, Sidra; Wojtuś, Anna; Repo, Eveliina; Ben Hammouda, Samia; Iakovleva, Evgenia; Sillanpää, Mika

2018-04-15

Silica-chitosan hybrid beads were synthesized via three different methods to investigate the selective recovery of REE from AMD. The influence of amino/non-amino silanes, high molecular weight/high viscous chitosan and N-/O- based ligands were studied and their effects on REE removal efficiencies were analyzed. The adsorption efficiencies of three various groups of modified beads were inspected with respect to feed pH, in a single and a multi-component system, and their affinities towards the light and heavy rare earth elements (LREE/ HREEs) were interpreted to understand the intra-series REE separation behavior. The focus of the study was mainly directed towards utilizing these fabricated beads for the recovery of valuable REEs from the real AMD obtained at three different sampling depths which was found rich in iron, sulfur and aluminum. Moreover, the selectivity of the beads towards REEs improved with silanized and ligand immobilized gels and their impacts on REE recovery in the presence of competing ions were successfully presented in this paper. Also, the synthesized beads showed rapid REE adsorption and recovery within a process time of 5 min. Group II adsorbents, synthesized by forming silica-chitosan hybrid beads followed by PAN/acac modifications, showed superiority over the other groups of adsorbents. Copyright © 2018 Elsevier B.V. All rights reserved.

Coping strategies may not be reflected by simulated performance-based measures of functional ability

PubMed Central

Riazi, Abbas; Boon, Mei Ying; Dain, Stephen J.; Bridge, Catherine

2012-01-01

Purpose To determine whether the Melbourne Low Vision Index (MLVI) can be used to characterise the ability to carry out Activities of Daily Living (ADL) in a group of older people with age-related macular degeneration (AMD) which was reflective of actual day-to-day function according to in-depth interviews which encompassed questions about personal and environmental coping strategies. Method Thirty-one individuals (23 females, 8 males, aged 79.1 ± 5.6 years) with AMD (16 dry, 15 wet) and no other ocular diseases underwent tests of clinical visual function, the MLVI and a semi-structured interview intended to highlight functionality in the home environment. Results Participants’ clinical visual measures were correlated with MLVI score such that poorer visual function was associated with poorer functional ability for daily living activities (p < 0.05). Moreover, part (a) of the MLVI, which is assessed by observation of task performance, has a significant correlation with the severity of AMD (p < 0.05). Semi-structured interviews revealed a mismatch between MLVI part (a) and self-reported functionality in their own home environment. Conclusion Low functionality score (total) with MLVI is associated with severity of AMD and poor clinical visual function. The disparity between observed measures of functional vision (MLVI part (a)) and self-reported measures in the MLVI and in the semi-structured interviews may be explained in part by individual participant coping and adaptation strategies. The MLVI is therefore reflective of function in unfamiliar environments where people with low vision may not have recourse to compensatory strategies.

Characterization of waste rock associated with acid drainage at the Penn Mine, California, by ground-based visible to short-wave infrared reflectance spectroscopy assisted by digital mapping

USGS Publications Warehouse

Montero, S.I.C.; Brimhall, G.H.; Alpers, Charles N.; Swayze, G.A.

2005-01-01

Prior to remediation at the abandoned Cu-Zn Penn Mine in the Foothills massive sulfide belt of the Sierra Nevada, CA, acid mine drainage (AMD) was created, in part, by the subaerial oxidation of sulfides exposed on several waste piles. To support remediation efforts, a mineralogical study of the waste piles was undertaken by acquiring reflectance spectra (measured in the visible to short-wave infrared range of light (0.35-2.5 ??m) using a portable, digitally integrated pen tablet PC mapping system with differential global positioning system and laser rangefinder support. Analysis of the spectral data made use of a continuum removal and band-shape comparison method, and of reference spectral libraries of end-member minerals and mineral mixtures. Identification of secondary Fe-bearing minerals focused on band matching in the region between 0.43 and 1.3 ??m. Identification of sheet and other silicates was based on band-shape analysis in the region between 1.9 and 2.4 ??m. Analysis of reflectance spectra of characterized rock samples from the mine helped in gauging the spectral response to particle size and mixtures. The resulting mineral maps delineated a pattern of accumulation of secondary Fe minerals, wherein centers of copiapite and jarosite that formed at low pH (<3) were surrounded successively by goethite and hematite, which mark progressive increases in pH. This pattern represents the evolution of acid solutions discharged from the pyritic waste piles and the subsequent accumulation of secondary precipitates by hydrolysis reactions. The results highlight the high capacity of the pyritic waste to release further acid mine drainage into the environment, as well as the effectiveness of the mapping method to detect subtle changes in surface mineralogy and to produce maps useful to agencies responsible for remediating the site. ?? 2004 Elsevier B.V. All rights reserved.

Mobility and natural attenuation of metals and arsenic in acidic waters of the drainage system of Timok River from Bor copper mines (Serbia) to Danube River.

PubMed

Đorđievski, Stefan; Ishiyama, Daizo; Ogawa, Yasumasa; Stevanović, Zoran

2018-06-22

Bor, Krivelj, and Bela Rivers belong to the watershed of Timok River, which is a tributary of transboundary Danube River. These rivers receive metal-rich acidic wastewater from metallurgical facilities and acid mine drainage (AMD) from mine wastes around Bor copper mines. The aim of this study was to determine the mobility and natural attenuation of metals and arsenic in rivers from Bor copper mines to Danube River during the year 2015. The results showed that metallurgical facilities had the largest impact on Bor River by discharging about 400 t of Cu per year through highly acidic wastewater (pH = 2.6). The highest measured concentrations of Cu in river water and sediments were 40 mg L -1 and 1.6%, respectively. Dissolution of calcite from limestone bedrock and a high concentration of bicarbonate ions in natural river water (about 250 mg L -1 ) enhanced the neutralization of acidic river water and subsequent chemical precipitation of metals and arsenic. Decreases in the concentrations of Al, Fe, Cu, As, and Pb in river water were mainly due to precipitation on the river bed. On the other hand, dilution played an important role in the decreases in concentrations of Mn, Ni, Zn, and Cd. Chemically precipitated materials and flotation tailings containing Fe-rich minerals (fayalite, magnetite, and pyrite) were transported toward Danube River during the periods of high discharge. This study showed that processes of natural attenuation in catchments with limestone bedrock play an important role in reducing concentrations of metals and arsenic in AMD-bearing river water.

Sulfate migration in a river affected by acid mine drainage from the Dabaoshan mining area, South China.

PubMed

Chen, Meiqin; Lu, Guining; Guo, Chuling; Yang, Chengfang; Wu, Jingxiong; Huang, Weilin; Yee, Nathan; Dang, Zhi

2015-01-01

Sulfate, a major component of acid mine drainage (AMD), its migration in an AMD-affected river which located at the Dabaoshan mine area of South China was investigated to pursue the remediation strategy. The existing factors of relatively low pH values of 2.8-3.9, high concentrations of SO4(2-) (∼1940 mg L(-1)) and Fe(3+) (∼112 mg L(-1)) facilitated the precipitation of schwertmannite (Fe8O8(OH)6SO4·nH2O) in the upstream river. Geochemical model calculations implied the river waters were supersaturated, creating the potential for precipitation of iron oxyhydroxides. These minerals evolved from schwertmannite to goethite with the increasing pH from 2.8 to 5.8 along the river. The concentration of heavy metals in river waters was great reduced as a result of precipitation effects. The large size of the exchangeable sulfate pool suggested that the sediments had a strong capacity to bind SO4(2-). The XRD results indicated that schwertmannite was the predominant form of sulfate-bearing mineral phases, which was likely to act as a major sulfate sink by incorporating water-borne sulfate into its internal structure and adsorbing it onto its surface. The small size of reduced sulfur pools and strong oxidative status in the surface sediments further showed that SO4(2-) shifting from water to sediment in form of sulfate reduction was not activated. In short, precipitation of sulfate-rich iron oxyhydroxides and subsequent SO4(2-) adsorption on these minerals as well as water dilution contributed to the attenuation of SO4(2-) along the river waters. Copyright © 2014 Elsevier Ltd. All rights reserved.

Evaluation of acidity estimation methods for mine drainage, Pennsylvania, USA.

PubMed

Park, Daeryong; Park, Byungtae; Mendinsky, Justin J; Paksuchon, Benjaphon; Suhataikul, Ratda; Dempsey, Brian A; Cho, Yunchul

2015-01-01

Eighteen sites impacted by abandoned mine drainage (AMD) in Pennsylvania were sampled and measured for pH, acidity, alkalinity, metal ions, and sulfate. This study compared the accuracy of four acidity calculation methods with measured hot peroxide acidity and identified the most accurate calculation method for each site as a function of pH and sulfate concentration. Method E1 was the sum of proton and acidity based on total metal concentrations; method E2 added alkalinity; method E3 also accounted for aluminum speciation and temperature effects; and method E4 accounted for sulfate speciation. To evaluate errors between measured and predicted acidity, the Nash-Sutcliffe efficiency (NSE), the coefficient of determination (R (2)), and the root mean square error to standard deviation ratio (RSR) methods were applied. The error evaluation results show that E1, E2, E3, and E4 sites were most accurate at 0, 9, 4, and 5 of the sites, respectively. Sites where E2 was most accurate had pH greater than 4.0 and less than 400 mg/L of sulfate. Sites where E3 was most accurate had pH greater than 4.0 and sulfate greater than 400 mg/L with two exceptions. Sites where E4 was most accurate had pH less than 4.0 and more than 400 mg/L sulfate with one exception. The results indicate that acidity in AMD-affected streams can be accurately predicted by using pH, alkalinity, sulfate, Fe(II), Mn(II), and Al(III) concentrations in one or more of the identified equations, and that the appropriate equation for prediction can be selected based on pH and sulfate concentration.

Acid Mine Drainage and Metal Sulfate Minerals in the Shasta Mining District, California

NASA Astrophysics Data System (ADS)

Livingston, J. D.; Murphy, W. M.; Miller, R. M.; Ayars, E. J.

2005-12-01

Metal sulfate minerals were collected at four surface water drainage sites during September and October of 2004 in the Shasta Mining District, southern Klamath Mountains, Shasta County, California and analyzed by X-ray fluorescence, atomic absorption spectroscopy, and X-ray diffraction to determine elements present, quantities of Fe, Cu, and Zn, and mineralogy. The Shasta Mining District produced major quantities of Cu, Zn, and pyrite (S) with minor amounts of Au, Ag, and Fe from massive sulfide bodies (Kinkel et al., 1956). Three study sites are located on Iron Mountain and one study site is at Bully Hill. Although mining occurred during a period of just over 100 years, it is estimated that acid mine drainage (AMD) will continue from Iron Mountain for over 3,200 years (Nordstrom and Alpers, 1998). AMD at the study sites produces blooms of metal sulfates during California's Mediterranean climate summer. The minerals readily dissolve in the "first flush" of seasonal rain creating runoff water of low pH with high amounts of dissolved metals (Bayless and Olyphant, 1993; Jambor et al., 2000). Data were examined for mineralogical changes in time and space and for zoning of minerals on a scale of centimeters. Sulfate mineral samples are complex with some samples composed of over a dozen different minerals. Site 1 is located on Spring Creek downstream from the Iron Mountain superfund remediation site, so levels of Fe, Cu, and Zn in the sulfates at this site are lower than at the other sites. Two site 1 samples from the same location taken a month apart show Ca, Fe, Cu, Sr, Y, and Sn, and the first sample also has detectable Br. The metal sulfates identified from the first visit are celestine, cesanite, chessexite, hectorfloresite, and ungemachite, and the mineralogy of the second visit is bilinite, epsomite, millosevichite, and anhydrite. The Fe bearing sulfate mineral during the first visit is ungemachite, but bilinite was the Fe bearing mineral at the time of the second visit. Analyses indicate a dynamic evolution of sulfate minerals at individual locations over time, mineralogical and chemical differences among individual locations at a site, and mineralogical zonations in individual samples.

Effect of heterogeneity and anisotropy related to the construction method on transfer processes in waste rock piles.

PubMed

Lahmira, Belkacem; Lefebvre, René; Aubertin, Michel; Bussière, Bruno

2016-01-01

Waste rock piles producing acid mine drainage (AMD) are partially saturated systems involving multiphase (gas and liquid) flow and coupled transfer processes. Their internal structure and heterogeneous properties are inherited from their wide-ranging material grain sizes, their modes of deposition, and the underlying topography. This paper aims at assessing the effect of physical heterogeneity and anisotropy of waste rock piles on the physical processes involved in the generation of AMD. Generic waste rock pile conditions were represented with the numerical simulator TOUGH AMD based on those found at the Doyon mine waste rock pile (Canada). Models included four randomly distributed material types (coarse, intermediate, fine and very fine-grained). The term "randomly" as used in this study means that the vertical profile and spatial distribution of materials in waste rock piles (internal structure) defy stratigraphy principles applicable to natural sediments (superposition and continuity). The materials have different permeability and capillary properties, covering the typical range of materials found in waste rock piles. Anisotropy with a larger horizontal than vertical permeability was used to represent the effect of pile construction by benches, while the construction by end-dumping was presumed to induce a higher vertical than horizontal permeability. Results show that infiltrated precipitation preferentially flows in fine-grained materials, which remain almost saturated, whereas gas flows preferentially through the most permeable coarse materials, which have higher volumetric gas saturation. Anisotropy, which depends on pile construction methods, often controls global gas flow paths. Construction by benches favours lateral air entry close to the pile slope, whereas end-dumping leads to air entry from the surface to the interior of the pile by secondary gas convection cells. These results can be useful to construct and rehabilitate waste rock piles to minimize AMD, while controlling gas flow and oxygen supply. Copyright © 2015 Elsevier B.V. All rights reserved.

Bacterial, Archaeal, and Eukaryotic Diversity across Distinct Microhabitats in an Acid Mine Drainage

PubMed Central

Mesa, Victoria; Gallego, Jose L. R.; González-Gil, Ricardo; Lauga, Béatrice; Sánchez, Jesús; Méndez-García, Celia; Peláez, Ana I.

2017-01-01

Acid mine drainages are characterized by their low pH and the presence of dissolved toxic metallic species. Microorganisms survive in different microhabitats within the ecosystem, namely water, sediments, and biofilms. In this report, we surveyed the microbial diversity within all domains of life in the different microhabitats at Los Rueldos abandoned mercury underground mine (NW Spain), and predicted bacterial function based on community composition. Sediment samples contained higher proportions of soil bacteria (AD3, Acidobacteria), as well as Crenarchaeota and Methanomassiliicoccaceae archaea. Oxic and hypoxic biofilm samples were enriched in bacterial iron oxidizers from the genus Leptospirillum, order Acidithiobacillales, class Betaproteobacteria, and archaea from the class Thermoplasmata. Water samples were enriched in Cyanobacteria and Thermoplasmata archaea at a 3–98% of the sunlight influence, whilst Betaproteobacteria, Thermoplasmata archaea, and Micrarchaea dominated in acid water collected in total darkness. Stalactites hanging from the Fe-rich mine ceiling were dominated by the neutrophilic iron oxidizer Gallionella and other lineages that were absent in the rest of the microhabitats (e.g., Chlorobi, Chloroflexi). Eukaryotes were detected in biofilms and open-air water samples, and belonged mainly to clades SAR (Alveolata and Stramenopiles), and Opisthokonta (Fungi). Oxic and hypoxic biofilms displayed higher proportions of ciliates (Gonostomum, Oxytricha), whereas water samples were enriched in fungi (Paramicrosporidium and unknown microbial Helotiales). Predicted function through bacterial community composition suggested adaptive evolutive convergence of function in heterogeneous communities. Our study showcases a broad description of the microbial diversity across different microhabitats in the same environment and expands the knowledge on the diversity of microbial eukaryotes in AMD habitats. PMID:28955322

Major hydrogeochemical processes in an acid mine drainage affected estuary.

PubMed

Asta, Maria P; Calleja, Maria Ll; Pérez-López, Rafael; Auqué, Luis F

2015-02-15

This study provides geochemical data with the aim of identifying and quantifying the main processes occurring in an Acid Mine Drainage (AMD) affected estuary. With that purpose, water samples of the Huelva estuary were collected during a tidal half-cycle and ion-ion plots and geochemical modeling were performed to obtain a general conceptual model. Modeling results indicated that the main processes responsible for the hydrochemical evolution of the waters are: (i) the mixing of acid fluvial water with alkaline ocean water; (ii) precipitation of Fe oxyhydroxysulfates (schwertmannite) and hydroxides (ferrihydrite); (iii) precipitation of Al hydroxysulfates (jurbanite) and hydroxides (amorphous Al(OH)3); (iv) dissolution of calcite; and (v) dissolution of gypsum. All these processes, thermodynamically feasible in the light of their calculated saturation states, were quantified by mass-balance calculations and validated by reaction-path calculations. In addition, sorption processes were deduced by the non-conservative behavior of some elements (e.g., Cu and Zn). Copyright © 2014 Elsevier Ltd. All rights reserved.

Investigation of Methane and Soil Carbon Dynamics Using Near Surface Geophysical Methods at the Tanoma Educational Wetland Site, Tanoma, Pennsylvania

NASA Astrophysics Data System (ADS)

Seidel, A. D.; Mount, G.

2017-12-01

Studies to constrain methane budgets of Pennsylvania have sought to quantify the amount and rate of fugitive methane released during industrial natural gas development. However, contributions from other environmental systems such as artificial wetlands used to treat part of the 300 million gallons per day of acid mine drainage (AMD) are often not understated or not considered. The artificial wetlands are sources of both biogenic and thermogenic methane and are used to treat AMD which would otherwise flow untreated into Pennsylvania surface waters. Our research utilizes a combination of indirect non-invasive geophysical methods (ground penetrating radar, GPR) and the complex refractive index model, aerial imagery, and direct measurements (coring and gas traps) to estimate the contribution of biogenic methane from wetlands and legacy thermogenic methane from acid mine drainage from a flooded coal mine at an artificial wetland designed to treat these polluted waters at Tanoma, Pennsylvania. Our approach uses (3D) GPR surveys to define the thickness of the soil from the surface to the regolith-bedrock interface to create a volume model of potential biogenic gas stores. Velocity data derived from the GPR is then used to calculate the dielectric permittivity of the soil and then modeled for gas content when considering the saturation, porosity and amount of soil present. Depth-profile cores are extracted to confirm soil column interfaces and determine changes in soil carbon content. Comparisons of gas content are made with gas traps placed across the wetlands that measure the variability of gaseous methane released. In addition, methane dissolved in the waters from biogenic processes in the wetland and thermogenic processes underground are analyzed by a gas chromatograph to quantify those additions. In sum, these values can then be extrapolated to estimate carbon stocks in AMD areas such as those with similar water quality and vegetation types in the Appalachian region. This research demonstrates the ability of indirect geophysical methods and the CRIM petrophysical model to estimate methane gas fluxes and total carbon stocks within wetlands. This will be of assistance to understand the impact of methane released from naturally occurring sources and legacy coal mines, not only commercial extraction and distribution.

DOE Office of Scientific and Technical Information (OSTI.GOV)

S Gilchrist; A Gates; E Elzinga

The abandoned Phillips sulfide mine in the critical Highlands watershed in New York has been shown to produce strongly acidic mine drainage (AMD) with anomalous metal contaminants in first-order streams that exceeded local water standards by up to several orders of magnitude (Gilchrist et al., 2009). The metal-sulfide-rich tailings also produce contaminated soils with pH < 4, organic matter < 2.5% and trace metals sequestered in soil oxides. A geochemical transect to test worst-case soil contamination showed that Cr, Co and Ni correlated positively with Mn, (r = 0.72, r = 0.89, r = 0.80, respectively), suggesting Mn-oxide sequestration andmore » that Cu and Pb correlated with Fe (r = 0.76, r = 0.83, respectively), suggesting sequestration in goethite. Ubiquitous, yellow coating on the mine wastes, including jarosite and goethite, is a carrier of the metals. Geochemical and {mu}-SXRF analyses determined Cu to be the major soil contaminant, {mu}-SXRF also demonstrated that the heterogeneous nature of the soil chemistry at the micro-meter scale is self-similar to those in the bulk soil samples. Generally metals decreased, with some fluctuations, rapidly downslope through suspension of fines and dissolution in AMD leaving the area of substantial contamination << 0.5 km from the source.« less

Uranium behaviour in an estuary polluted by mining and industrial effluents: the Ría of Huelva (SW of Spain).

PubMed

Hierro, A; Martín, J E; Olías, M; Vaca, F; Bolivar, J P

2013-10-15

This paper describes a comprehensive study of the behaviour of U in the Ría of Huelva estuary, formed by the Tinto and Odiel rivers. This ecosystem is conditioned by two hydrochemical facts: one connected with the acid mining drainage (AMD) generated in the first section of the river basins, and another one related to the fertilizer industry located at the estuary. AMD gives a singular character to these rivers; low pH and high redox potential that keep high amounts of toxic elements and radionuclides in dissolution. Most of the data for dissolved U in estuaries indicate conservative mixing, but there are examples of non-conservative behaviour attributed to oxidation/reduction processes or solubility variations. In the Ría of Huelva estuary the U shows a non-conservative behaviour due to solubility changes produced by variations in the pH. A complete removal of riverine dissolved U is observed in a pH range of 4-6. At higher pH values, U release from suspended matter, and probably also from sediments into the dissolved phase is found. Copyright © 2013 Elsevier Ltd. All rights reserved.

Use of Walnut Shell Powder to Inhibit Expression of Fe2+-Oxidizing Genes of Acidithiobacillus Ferrooxidans

PubMed Central

Li, Yuhui; Liu, Yehao; Tan, Huifang; Zhang, Yifeng; Yue, Mei

2016-01-01

Acidithiobacillus ferrooxidans is a Gram-negative bacterium that obtains energy by oxidizing Fe2+ or reduced sulfur compounds. This bacterium contributes to the formation of acid mine drainage (AMD). This study determined whether walnut shell powder inhibits the growth of A. ferrooxidans. First, the effects of walnut shell powder on Fe2+ oxidization and H+ production were evaluated. Second, the chemical constituents of walnut shell were isolated to determine the active ingredient(s). Third, the expression of Fe2+-oxidizing genes and rus operon genes was investigated using real-time polymerase chain reaction. Finally, growth curves were plotted, and a bioleaching experiment was performed to confirm the active ingredient(s) in walnut shells. The results indicated that both walnut shell powder and the phenolic fraction exert high inhibitory effects on Fe2+ oxidation and H+ production by A. ferrooxidans cultured in standard 9K medium. The phenolic components exert their inhibitory effects by down-regulating the expression of Fe2+-oxidizing genes and rus operon genes, which significantly decreased the growth of A. ferrooxidans. This study revealed walnut shell powder to be a promising substance for controlling AMD. PMID:27144574

Laboratory and field evaluation of a flushable oxic limestone drain for treatment of net-acidic drainage from a flooded anthracite mine, Pennsylvania, USA

USGS Publications Warehouse

Cravotta, C.A.

2008-01-01

This paper demonstrates the use of dissolution-rate data obtained in the laboratory to indicate the potential quality of effluent from a field-scale oxic limestone drain (OLD) treatment system for neutralization of dilute acidic mine drainage (AMD). Effluent from the Reevesdale Mine South Dip Tunnel, a large source of AMD and base flow to the Wabash Creek and Little Schuylkill River in the Southern Anthracite Coalfield of east-central Pennsylvania, is representative of AMD with low concentrations but high loadings of dissolved Fe, Al and other metals because of a high flow rate. In January 2003, rapid neutralization of the AMD from the Reevesdale Mine was achieved in laboratory tests of its reaction rate with crushed limestone in closed, collapsible containers (Cubitainers). The tests showed that net-alkaline effluent could be achieved with retention times greater than 3 h and that effluent alkalinities and associated dissolution rates were equivalent for Fe(OH)3-coated and uncoated limestone. On the basis of the laboratory results, a flushable OLD containing 1450 metric tons of high-purity calcitic limestone followed by two 0.7-m deep wetlands were constructed at the Reevesdale Mine. During the first year of operation, monthly data at the inflow, outflow and intermediate points within the treatment system were collected (April 2006-2007). The inflow to the treatment system ranged from 6.8 to 27.4 L/s, with median pH of 4.7, net acidity of 9.1 mg/L CaCO3, and concentrations of dissolved Al, Fe and Mn of 1.0, 1.9 and 0.89 mg/L, respectively. The corresponding effluent from the OLD had computed void-volume retention times of 4.5-18 h, with median pH of 6.6, net acidity of -93.2 mg/L CaCO3, and concentrations of dissolved Al, Fe and Mn of <0.1, 0.08 and 0.52 mg/L, respectively. The wetlands below the OLD were effective for retaining metal-rich solids flushed at monthly or more frequent intervals from the OLD, but otherwise had little effect on the effluent quality. During the first year of operation, approximately 43 metric tons of limestone were dissolved and 2 metric tons of Al, Fe and Mn were precipitated within the OLD. However, because of the accumulation of these metals within the OLD and possibly other debris from the mine, the effectiveness of the treatment system declined. Despite the installation of a flush-pipe network at the base of the OLD to remove precipitated solids, the limestone bed clogged near the inflow. Consequently, a large fraction of the AMD bypassed the treatment system. To promote flow through the OLD, the flush pipes were open continuously during the last 4 months of the study; however, this effluent was only partially treated because short-circuiting through the pipes decreased contact between the effluent and limestone. A reconfiguration of the flow path through the limestone bed from horizontal to vertical upward could increase the limestone surface area exposed to the metal-laden influent, increase the cross-sectional area perpendicular to flow, decrease the flow path for solids removal, and, consequently, decrease potential for clogging.

Metals in agricultural produce associated with acid-mine drainage in Mount Morgan (Queensland, Australia).

PubMed

Vicente-Beckett, Victoria A; McCauley, Gaylene J Taylor; Duivenvoorden, Leo J

2016-01-01

Acid-mine drainage (AMD) into the Dee River from the historic gold and copper mine in Mount Morgan, Queensland (Australia) has been of concern to farmers in the area since 1925. This study sought to determine the levels of AMD-related metals and sulfur in agricultural produce grown near the mine-impacted Dee River, compare these with similar produce grown in reference fields (which had no known AMD influence), and assess any potential health risk using relevant Australian or US guidelines. Analyses of lucerne (Medicago sativa; also known as alfalfa) from five Dee fields showed the following average concentrations (mg/kg dry basis): Cd < 1, Cu 11, Fe 106, Mn 52, Pb < 5, Zn 25 and S 3934; similar levels were found in lucerne hay (used as cattle feed) from two Dee fields. All lucerne and lucerne hay data were generally comparable with levels found in the lucerne reference fields, suggesting no AMD influence; the levels were within the US National Research Council (US NRC) guidelines for maximum tolerable cattle dietary intake. Pasture grass (also cattle feed) from two fields in the Dee River floodplains gave mean concentrations (mg/kg dry) of Cd 0.14, Cu 12, Fe 313, Mn 111, Pb 1.4, Zn 86 and S 2450. All metal levels from the Dee and from reference sites were below the US NRC guidelines for maximum tolerable cattle dietary intake; however, the average Cd, Cu and Fe levels in Dee samples were significantly greater than the corresponding levels in the pasture grass reference sites, suggesting AMD influence in the Dee samples. The average levels in the edible portions of mandarin oranges (Citrus reticulata) from Dee sites (mg/kg wet weight) were Cd 0.011, Cu 0.59, Fe 2.2, Mn 0.56, Pb 0.18, S 91 and Zn 0.96. Cd and Zn were less than or close to, average Fe and Mn levels were at most twice, Cd 1.8 or 6.5 times, and Pb 8.5 or 72 times the maximum levels in raw oranges reported in the US total diet study (TDS) or the Australian TDS, respectively. Average Cd, Fe, Mn, Pb and Zn levels in the citrus reference samples were found to exceed the maximum reported in one or both TDS surveys. Cu, Fe, Mn, Pb and Zn plant-soil transfer factor (TF) values were < 1 for all agricultural samples from both Dee and reference sites, suggesting relatively poor transfer of these metals from soil to plant. In the case of Cd, TF values for Dee pasture grass and citrus fruit samples were 0.14 and 0.73, respectively; lucerne and lucerne hay from both Dee and reference sites gave TF = 10, suggesting some potential risk to cattle, although this conclusion is tentative because Cd levels were close to or less than the detection limit. TF values for S in lucerne, lucerne hay, pasture grass and mandarin oranges from Dee sites were 18, 14, 3 and 3.6, respectively, indicating that S in soil was readily available to plant or fruit. Sulfur in pasture grass and citrus fruit (TF = 11 for both) was apparently more bioavailable at the reference sites than at the Dee sites (TF = 3.0 for pasture grass; TF = 3.6 for citrus fruit).

Characterization of Acid Mine Drainage Sources Using Stable and Radiogenic Isotopes, Chalk Creek, Colorado

NASA Astrophysics Data System (ADS)

Cordalis, D.; Michel, R.; Williams, M.; Wireman, M.

2003-12-01

Acid mine drainage (AMD) affects many streams throughout the western United States. Understanding flow dynamics and sources within a fractured rock setting is necessary in outlining a potential remediation strategy for AMD. Radiogenic and stable isotopes of water were used in the Mary Murphy Mine, Chalk Creek, Colorado, in order to characterize flowpaths and sourcewaters. By delineating the sources of the mine water, groundwater, and event water, we may be able to target remediation techniques for individual contamination sources. Moreover, results from this research provide insights into groundwater flow systems in mountain environments of the Colorado Rockies. Tritium, a cosmogenic isotope of hydrogen, has a half-life 12.43y and is useful for studying hydrologic processes at the decadal time scale and can be used as an effective tracer when traditional chemical tracers are non-conservative. Hydrometric information showed that discharge from the mine adit exhibited a hydrograph characteristic of snowmelt runoff. However, mixing models using stable water isotopes (D and 18O) found less than 7% of the mine's peak discharge was from snowmelt, suggesting a regional groundwater dominated system. Mine interior samples fell into two characteristic groupings: either from the extreme north side of the drift which contained most of the zinc contamination, and all other locations. The waters from the north drift, MVN-3 and MVN-4, had lower 18O values, -17.62 per mil and -17.17 per mil, respectively, than did any of the other locations, suggesting a seasonal snowmelt input. However, the tritium values associated with MVN-3 and MVN-4 suggest at least some mixing, with values of 13.4 TU and 12.5 TU, respectively. Surface water samples from Chalk Creek show average tritium values of 11.1 TU, and 18O values of -14.87 per mil. Groundwater samples were captured using monitoring wells, and plotted according to the depth of screening. Alluvial wells carried a seasonal signal similar to the surface water as expected; 11.6 TU and -15.15 per mil averages for tritium and 18O. In contrast, bedrock wells showed a longer residence time and snowmelt recharge. The combination of radiogenic and stable isotopes within and near the Mary Murphy Mine may provide a useful tool for studying interactions between groundwaters and surfacewaters in a fractured rock setting. Remediation techniques can be directed more appropriately, and cost effectively, by the characterization of flowpaths within the mine as well.

Acid mine drainage pollution in the Tinto and Odiel rivers (Iberian Pyrite Belt, SW Spain) and bioavailability of the transported metals to the Huelva Estuary.

PubMed

Nieto, José Miguel; Sarmiento, Aguasanta M; Olías, Manuel; Canovas, Carlos R; Riba, Inmaculada; Kalman, Judit; Delvalls, T Angel

2007-05-01

The Tinto and Odiel rivers are seriously affected by acid mine drainage (AMD) from the long-term mining activities in Iberian Pyrite Belt (IPB). As a consequence, the Huelva estuary is heavily contaminated by metals and metalloids. This study presents an estimation of the seasonal variation, and the dissolved contaminant load transported by both rivers from February 2002 to September 2004. Besides, toxicity and bioaccumulation tests with the sediments of the estuary have been conducted in order to measure the mobility of the toxic metals. Results show that the Tinto and Odiel rivers transport enormous quantities of dissolved metals to the estuary: 7900 t yr(-1) of Iron (Fe), 5800 t yr(-1) Aluminium (Al), 3500 t yr(-1) Zinc (Zn), 1700 t yr(-1) Copper (Cu), 1600 t yr(-1) Manganese (Mn) and minor quantities of other metals and metalloids. These values represent 37% of the global gross flux of dissolved Zn transported by rivers in to the ocean, and 15% of the global gross flux of dissolved Cu. These metals and metalloids usually sink in the estuarine sediments due to pH and salinity changes. The increase of salinity in the estuary favours the adsorption and trapping of metals. For this reason, the mobility and bioavailability of metals such as Zn, Cd and Cu is higher in sediments located in the area of fresh water influence that in sediments located in the marine influenced area of the estuary, showing a higher percentage of fractionation and bioaccumulation of these metals in the station influenced by the fresh water environment.

Gene Loss and Horizontal Gene Transfer Contributed to the Genome Evolution of the Extreme Acidophile “Ferrovum”

PubMed Central

Ullrich, Sophie R.; González, Carolina; Poehlein, Anja; Tischler, Judith S.; Daniel, Rolf; Schlömann, Michael; Holmes, David S.; Mühling, Martin

2016-01-01

Acid mine drainage (AMD), associated with active and abandoned mining sites, is a habitat for acidophilic microorganisms that gain energy from the oxidation of reduced sulfur compounds and ferrous iron and that thrive at pH below 4. Members of the recently proposed genus “Ferrovum” are the first acidophilic iron oxidizers to be described within the Betaproteobacteria. Although they have been detected as typical community members in AMD habitats worldwide, knowledge of their phylogenetic and metabolic diversity is scarce. Genomics approaches appear to be most promising in addressing this lacuna since isolation and cultivation of “Ferrovum” has proven to be extremely difficult and has so far only been successful for the designated type strain “Ferrovum myxofaciens” P3G. In this study, the genomes of two novel strains of “Ferrovum” (PN-J185 and Z-31) derived from water samples of a mine water treatment plant were sequenced. These genomes were compared with those of “Ferrovum” sp. JA12 that also originated from the mine water treatment plant, and of the type strain (P3G). Phylogenomic scrutiny suggests that the four strains represent three “Ferrovum” species that cluster in two groups (1 and 2). Comprehensive analysis of their predicted metabolic pathways revealed that these groups harbor characteristic metabolic profiles, notably with respect to motility, chemotaxis, nitrogen metabolism, biofilm formation and their potential strategies to cope with the acidic environment. For example, while the “F. myxofaciens” strains (group 1) appear to be motile and diazotrophic, the non-motile group 2 strains have the predicted potential to use a greater variety of fixed nitrogen sources. Furthermore, analysis of their genome synteny provides first insights into their genome evolution, suggesting that horizontal gene transfer and genome reduction in the group 2 strains by loss of genes encoding complete metabolic pathways or physiological features contributed to the observed diversification. PMID:27303384

Application of fuel cell for pyrite and heavy metal containing mining waste

NASA Astrophysics Data System (ADS)

Keum, H.; Ju, W. J.; Jho, E. H.; Nam, K.

2015-12-01

Once pyrite and heavy metal containing mining waste reacts with water and air it produces acid mine drainage (AMD) and leads to the other environmental problems such as contamination of surrounding soils. Pyrite is the major source of AMD and it can be controlled using a biological-electrochemical dissolution method. By enhancing the dissolution of pyrite using fuel cell technology, not only mining waste be beneficially utilized but also be treated at the same time by. As pyrite-containing mining waste is oxidized in the anode of the fuel cell, electrons and protons are generated, and electrons moves through an external load to cathode reducing oxygen to water while protons migrate to cathode through a proton exchange membrane. Iron-oxidizing bacteria such as Acidithiobacillus ferrooxidans, which can utilize Fe as an electron donor promotes pyrite dissolution and hence enhances electrochemical dissolution of pyrite from mining waste. In this study mining waste from a zinc mine in Korea containing 17 wt% pyrite and 9% As was utilized as a fuel for the fuel cell inoculated with A. ferrooxidans. Electrochemically dissolved As content and chemically dissolved As content was compared. With the initial pH of 3.5 at 23℃, the dissolved As concentration increased (from 4.0 to 13 mg/L after 20 d) in the fuel cell, while it kept decreased in the chemical reactor (from 12 to 0.43 mg/L after 20 d). The fuel cell produced 0.09 V of open circuit voltage with the maximum power density of 0.84 mW/m2. Dissolution of As from mining waste was enhanced through electrochemical reaction. Application of fuel cell technology is a novel treatment method for pyrite and heavy metals containing mining waste, and this method is beneficial for mining environment as well as local community of mining areas.

Performance assessment of a single-layer moisture store-and-release cover system at a mine waste rock pile in a seasonally humid region (Nova Scotia, Canada).

PubMed

Power, Christopher; Ramasamy, Murugan; Mkandawire, Martin

2018-03-03

Cover systems are commonly applied to mine waste rock piles (WRPs) to control acid mine drainage (AMD). Single-layer covers utilize the moisture "store-and-release" concept to first store and then release moisture back to the atmosphere via evapotranspiration. Although more commonly used in semi-arid and arid climates, store-and-release covers remain an attractive option in humid climates due to the low cost and relative simplicity of installation. However, knowledge of their performance in these climates is limited. The objective of this study was to assess the performance of moisture store-and-release covers at full-scale WRPs located in humid climates. This cover type was installed at a WRP in Nova Scotia, Canada, alongside state-of-the-art monitoring instrumentation. Field monitoring was conducted over 5 years to assess key components such as meteorological conditions, cover material water dynamics, net percolation, surface runoff, pore-gas, environmental receptor water quality, landform stability and vegetation. Water balances indicate small reductions in water influx to the waste rock (i.e., 34 to 28% of precipitation) with the diminished AMD release also apparent by small improvements in groundwater quality (increase in pH, decrease in sulfate/metals). Surface water quality analysis and field observations of vegetative/aquatic life demonstrate significant improvements in the surface water receptor. The WRP landform is stable and the vegetative cover is thriving. This study has shown that while a simple store-and-release cover may not be a highly effective barrier to water infiltration in humid climates, it can be used to (i) eliminate contaminated surface water runoff, (ii) minimize AMD impacts to surface water receptor(s), (iii) maintain a stable landform, and (iv) provide a sustainable vegetative canopy.

Chelant-enhanced washing of CCA-contaminated soil: Coupled with selective dissolution or soil stabilization.

PubMed

Beiyuan, Jingzi; Lau, Abbe Y T; Tsang, Daniel C W; Zhang, Weihua; Kao, Chih-Ming; Baek, Kitae; Ok, Yong Sik; Li, Xiang-Dong

2018-01-15

Remediation of CCA-contaminated soil (Cr, Cu, and As) by biodegradable chelant-enhanced washing (EDDS, S,S-ethylene-diamine-disuccinic-acid) needs further enhancement. This study investigated the effectiveness of coupling with pre-treatment by selective dissolution and post-treatment by soil amendments, respectively. Three groups of reagents (reductants, alkaline solvents, and organic ligands) were adopted in the pre-treatment to dissolve the oxide minerals before EDDS extraction. In the post-treatment, soil amendments (coal fly ash (CFA), acid mine drainage sludge (AMDS), green waste compost (GWC)), and their mixtures) were used for a 2-month stabilization after 2-h EDDS washing. Multi-endpoint evaluation was performed by assessing the chemical state, leachability, mobility, bioaccessibility, and plant-availability of residual metal(loid)s as well as the cytotoxicity, enzyme activities, and available nutrients of the treated soils. Pre-treatment by dithionite-citrate-bicarbonate significantly enhanced extraction efficiency, but also increased the leachability of As and Cr and bioaccessibility of Cr in the treated soils. While sodium hydroxide removed the majority of As without increasing its leachability and bioaccessibility, it increased the cytotoxicity and inhibited the acid phosphatase activity. Post-treatment with AMDS and CFA effectively controlled the mobility and leachability of residual As and Cr after EDDS washing. However, destabilized Cu was only marginally immobilized by GWC due to strong Cu-EDDS complexation. The bioaccessibility and phytoavailability of Cu was primarily reduced by EDDS washing, while those of As and Cr could be attenuated by AMDS and CFA. This study indicates that coupling chemical extraction with subsequent soil amendment plays complementary roles in mitigating effects of residual metal(loid)s and improving environmental quality. Copyright © 2017 Elsevier B.V. All rights reserved.

Metal-fluxes characterization at a catchment scale: Study of mixing processes and end-member analysis in the Meca River watershed (SW Spain)

NASA Astrophysics Data System (ADS)

Cánovas, C. R.; Macías, F.; Olías, M.; López, R. Pérez; Nieto, J. M.

2017-07-01

Fluxes of acidity and contaminants from acid mine drainage (AMD) sources to the receiving surface water bodies were studied in a mining-impacted watershed (Meca River, SW Spain) using a novel methodology based on the joint application of EMMA and MIX codes. The application of EMMA and elemental ratios allowed delimiting the end-members responsible for water quality variations at a catchment scale. The further application of MIX quantified the significant impact of AMD on the river quality; less than 10% of AMD relative contribution is enough to maintain acidic conditions during most of the year. The mixing model also provided information about the element mobility, distinguishing those elements with a quasi-conservative behavior (e.g., Cu, Zn, Al, Co or Ni) from those affected by mineral precipitation/dissolution (e.g., K, Si, Na, Sr, Ca, Fe, Pb, or As). Floods are the main driver of dissolved and, mainly particulate, contaminants in the catchment. Thus, the first rainfall events in November only accounted for 19% of the annual Meca flow but yielded between 26 and 43% of the net acidity and dissolved metal loads (mainly, Fe, As and Pb). Concerning particulate transport, around 332 tons of particulate Fe, 49 tons of Al, 0.79 tons of As and 0.37 tons of Pb were recorded during these first floods. The particulate As concentration can be up to 34 times higher than the dissolved one during floods and between 2 and 4 times higher for Fe, Pb and Cr. This integrated modeling approach could be a promising and useful tool to face future restoration plans in derelict mines worldwide. This approach would allow prioritizing remedial measures, achieving an environmental and cost-effective restoration of degraded areas.

Thermodynamic controls on the kinetics of microbial low-pH Fe(II) oxidation.

PubMed

Larson, Lance N; Sánchez-España, Javier; Kaley, Bradley; Sheng, Yizhi; Bibby, Kyle; Burgos, William D

2014-08-19

Acid mine drainage (AMD) is a major worldwide environmental threat to surface and groundwater quality. Microbial low-pH Fe(II) oxidation could be exploited for cost-effective AMD treatment; however, its use is limited because of uncertainties associated with its rate and ability to remove Fe from solution. We developed a thermodynamic-based framework to evaluate the kinetics of low-pH Fe(II) oxidation. We measured the kinetics of low-pH Fe(II) oxidation at five sites in the Appalachian Coal Basin in the US and three sites in the Iberian Pyrite Belt in Spain and found that the fastest rates of Fe(II) oxidation occurred at the sites with the lowest pH values. Thermodynamic calculations showed that the Gibbs free energy of Fe(II) oxidation (ΔG(oxidation)) was also most negative at the sites with the lowest pH values. We then conducted two series of microbial Fe(II) oxidation experiments in laboratory-scale chemostatic bioreactors operated through a series of pH values (2.1-4.2) and found the same relationships between Fe(II) oxidation kinetics, ΔG(oxidation), and pH. Conditions that favored the fastest rates of Fe(II) oxidation coincided with higher Fe(III) solubility. The solubility of Fe(III) minerals, thus plays an important role on Fe(II) oxidation kinetics. Methods to incorporate microbial low-pH Fe(II) oxidation into active and passive AMD treatment systems are discussed in the context of these findings. This study presents a simplified model that describes the relationship between free energy and microbial kinetics and should be broadly applicable to many biogeochemical systems.

Preliminary study of acrylamide monomer decomposition during methane fermentation of dairy waste sludge.

PubMed

Mroczek, Ewelina; Konieczny, Piotr; Lewicki, Andrzej; Waśkiewicz, Agnieszka; Dach, Jacek

2016-07-01

Polyacrylamide (PAM) used in sludge dewatering exists widely in high-solid anaerobic digestion. Acrylamide is registered in the list of chemicals demonstrating toxic, carcinogenic and mutagenic properties. Therefore, it is reasonable to ask about the mobility of such residual substances in the environment. The study was carried out to assess the impact of the mesophilic (39±1°C) and thermophilic (54±1°C) fermentation process on the level of acrylamide monomer (AMD) content in the dairy sludge. The material was analysed using high-performance liquid chromatography (HPLC) for quantification of AMD. The results indicate that the process of methane fermentation continues regardless of the temperature effects on the degradation of AMD in dairy sludge. The degree of reduction of acrylamide monomer for thermophilic fermentation is 100%, while for mesophilic fermentation it is 91%. In practice, this means that biogas technology eliminates the risk of AMD migration to plant tissue. Moreover, it should be stressed that 90% of cumulative biogas and methane production was reached one week earlier under thermophilic conditions - the dynamics of the methanisation process were over 20% faster. Copyright © 2016. Published by Elsevier B.V.

Use of EDTA in modified kinetic testing for contaminated drainage prediction from waste rocks: case of the Lac Tio mine.

PubMed

Plante, Benoît; Benzaazoua, Mostafa; Bussière, Bruno; Kandji, El-Hadji-Babacar; Chopard, Aurélie; Bouzahzah, Hassan

2015-05-01

The tools developed for acid mine drainage (AMD) prediction were proven unsuccessful to predict the geochemical behavior of mine waste rocks having a significant chemical sorption capacity, which delays the onset of contaminated neutral drainage (CND). The present work was performed in order to test a new approach of water quality prediction, by using a chelating agent solution (0.03 M EDTA, or ethylenediaminetetraacetic acid) in kinetic testing used for the prediction of the geochemical behavior of geologic material. The hypothesis underlying the proposed approach is that the EDTA solution should chelate the metals as soon as they are released by sulfide oxidation, inhibiting their sorption or secondary precipitation, and therefore reproduce a worst-case scenario where very low metal attenuation mechanisms are present in the drainage waters. Fresh and weathered waste rocks from the Lac Tio mine (Rio tinto, Iron and Titanium), which are known to generate Ni-CND at the field scale, were submitted to small-scale humidity cells in control tests (using deionized water) and using an EDTA solution. Results show that EDTA effectively prevents the metals to be sorbed or to precipitate as secondary minerals, therefore enabling to bypass the delay associated with metal sorption in the prediction of water quality from these materials. This work shows that the use of a chelating agent solution is a promising novel approach of water quality prediction and provides general guidelines to be used in further studies, which will help both practitioners and regulators to plan more efficient management and disposal strategies of mine wastes.

Influence of Acid Mine Drainage (AMD) on recent phyto- and zooplankton in "the Anthropogenic Lake District" in south-west Poland

NASA Astrophysics Data System (ADS)

Sienkiewicz, Elwira; Gasiorowski, Michal

2015-04-01

In south-west Poland (central Europe) many the post-mining lakes formed so-called "the Anthropogenic Lake District". Areas, where water comes in contact with lignite beds characterized by high concentration of sulfide minerals are called Acid Mine Drainage (AMD). Pyrite oxidation and other sulfide compounds caused release sulfuric acids and heavy metal ions. These processes caused decline of water pH, sometimes to extremely low pH < 2.8. Presently, pit lakes located in south-west Poland have water pH ranged between 2.7 and 8.9. Differences of water reaction in the mine lakes depend on many factors, such as bedrock buffer capacity, geological structure of carboniferous area, exploitation technique of lignite, methods of filling and water supply of reservoirs and their age. During the evolution of lakes' ecosystems, sulfate-iron-calcium type of waters occurring in acid lakes will transform in alkaline hydrogen-carbonate-calcium type of waters. Due to the different time of the completion of lignite exploitation, lakes' age varied between forty and over one hundred years. Studies showed that younger lakes are more acidic in compare to older. To estimate impact of AMD we analyzed recent diversity of diatoms and Cladocera remains and water chemistry from extremely acidic, relatively young lakes and from alkaline, older water bodies. As we expected, flora and fauna from acidic lakes have shown very low diversity and species richness. Among diatoms, Eunotia exigua (Bréb. ex Kütz.) Rabenhorst and/or E. paludosa Grunow were dominated taxa, while fauna Cladocera did not occurred in lakes with water pH < 3. On this area, exploitation of lignite continued up to 1973. Older lakes were formed in the region where the mine started work in 1880 and lignite mining stopped in 1926. Measurements of pH value in situ point to neutral or alkaline water, but because of the possibility of hysteresis phenomenon, the studies of phyto- and zooplankton have shown if there has already been a widespread neutralization of lake ecosystems, what encompassing both recovery of water chemistry and rebuilding of biota communities. Studies have confirmed, that phyto- and zooplankton living nowadays in lakes located on this area, where exploitation of lignite ended at the beginning of 20th century, indicate completely recovery from acidification caused by coal mine activities. Presently, the lakes were dominated by planktonic diatoms and Cladocera taxa, such as Discostella pseudostelligera (Hust.) Houk & Klee and Bosmina longirostris, respectively.

Cloning and analysis of the positively acting regulatory gene amdR from Aspergillus nidulans.

PubMed Central

Andrianopoulos, A; Hynes, M J

1988-01-01

The positively acting regulatory gene amdR of Aspergillus nidulans coordinately regulates the expression of four unlinked structural genes involved in acetamide (amdS), omega amino acid (gatA and gabA), and lactam (lamA) catabolism. By the use of DNA-mediated transformation of A. nidulans, the amdR regulatory gene was cloned from a genomic cosmid library. Southern blot analysis of DNA from various loss-of-function amdR mutants revealed the presence of four detectable DNA rearrangements, including a deletion, an insertion, and a translocation. No detectable DNA rearrangements were found in several constitutive amdRc mutants. Analysis of the fate of amdR-bearing plasmids in transformants showed that 10 to 20% of the transformation events were homologous integrations or gene conversions, and this phenomenon was exploited in developing a strategy by which amdRc and amdR- alleles can be readily cloned and analyzed. Examination of the transcription of amdR by Northern blot (RNA blot) analysis revealed the presence of two mRNAs (2.7 and 1.8 kilobases) which were constitutively synthesized at a very low level. In addition, amdR transcription did not appear to depend on the presence of a functional amdR product nor was it altered in amdRc mutants. The dosage effects of multiple copies of amdR in transformants were examined, and it was shown that such transformants exhibited stronger growth than did the wild type on acetamide and pyrrolidinone media, indicating increased expression of the amdS and lamA genes, respectively. These results were used to formulate a model for amdR-mediated regulation of gene expression in which the low constitutive level of amdR product sets the upper limits of basal and induced transcription of the structural genes. Multiple copies of 5' sequences from the amdS gene can result in reduced growth on substrates whose utilization is dependent on amdR-controlled genes. This has been attributed to titration of limiting amdR gene product. Strong support for this proposal was obtained by showing that multiple copies of the amdR gene can reverse this phenomenon (antititration). Images PMID:3062382

Abandoned mine drainage in the Swatara Creek Basin, southern anthracite coalfield, Pennsylvania, USA: 2. performance of treatment systems

USGS Publications Warehouse

Cravotta, Charles A.

2010-01-01

A variety of passive and semi-passive treatment systems were constructed by state and local agencies to neutralize acidic mine drainage (AMD) and reduce the transport of dissolved metals in the upper Swatara Creek Basin in the Southern Anthracite Coalfield in eastern Pennsylvania. To evaluate the effectiveness of selected treatment systems installed during 1995–2001, the US Geological Survey collected water-quality data at upstream and downstream locations relative to each system eight or more times annually for a minimum of 3 years at each site during 1996–2007. Performance was normalized among treatment types by dividing the acid load removed by the size of the treatment system. For the limestone sand, open limestone channel, oxic limestone drain, anoxic limestone drain (ALD), and limestone diversion well treatment systems, the size was indicated by the total mass of limestone; for the aerobic wetland systems, the size was indicated by the total surface area of ponds and wetlands. Additionally, the approximate cost per tonne of acid treated over an assumed service life of 20 years was computed. On the basis of these performance metrics, the limestone sand, ALD, oxic limestone drain, and limestone diversion wells had similar ranges of acid-removal efficiency and cost efficiency. However, the open limestone channel had lower removal efficiency and higher cost per ton of acid treated. The wetlands effectively attenuated metals transport but were relatively expensive considering metrics that evaluated acid removal and cost efficiency. Although the water-quality data indicated that all treatments reduced the acidity load from AMD, the ALD was most effective at producing near-neutral pH and attenuating acidity and dissolved metals. The diversion wells were effective at removing acidity and increasing pH of downstream water and exhibited unique potential to treat moderate to high flows associated with storm flow conditions.

Potential of fly ash for neutralisation of acid mine drainage.

PubMed

Qureshi, Asif; Jia, Yu; Maurice, Christian; Öhlander, Björn

2016-09-01

Lignite (PK), bituminous (FI) and biomass (SE) fly ashes (FAs) were mineralogically and geochemically characterised, and their element leachability was studied with batch leaching tests. The potential for acid neutralisation (ANP) was quantified by their buffering capacity, reflecting their potential for neutralisation of acid mine drainage. Quartz was the common mineral in FAs detected by XRD with iron oxide, anhydrite, and magnesioferrite in PK, mullite and lime in FI, and calcite and anorthite in SE. All the FAs had high contents of major elements such as Fe, Si, Al and Ca. The Ca content in SE was six and eight times higher compared to PK and FI, respectively. Sulphur content in PK and SE was one magnitude higher than FI. Iron concentrations were higher in PK. The trace element concentrations varied between the FAs. SE had the highest ANP (corresponding to 275 kg CaCO3 tonne(-1)) which was 15 and 10 times higher than PK and FI, respectively. The concentrations of Ca(2+), SO4 (2-), Na(+) and Cl(-) in the leachates were much higher compared to other elements from all FA samples. Iron, Cu and Hg were not detected in any of the FA leachates because of their mild to strong alkaline nature with pH ranging from 9 to 13. Potassium leached in much higher quantity from SE than from the other ashes. Arsenic, Mn and Ni leached from PK only, while Co and Pb from SE only. The concentrations of Zn were higher in the leachates from SE. The FAs used in this study have strong potential for the neutralisation of AMD due to their alkaline nature. However, on the other hand, FAs must be further investigated, with scaled-up experiments before full-scale application, because they might leach pronounced concentrations of elements of concern with decreasing pH while neutralising AMD.

Microbial reduction of ferric iron oxyhydroxides as a way for remediation of grey forest soils heavily polluted with toxic metals by infiltration of acid mine drainage

NASA Astrophysics Data System (ADS)

Georgiev, Plamen; Groudev, Stoyan; Spasova, Irena; Nicolova, Marina

2015-04-01

The abandoned uranium mine Curilo is a permanent source of acid mine drainage (AMD) which steadily contaminated grey forest soils in the area. As a result, the soil pH was highly acidic and the concentration of copper, lead, arsenic, and uranium in the topsoil was higher than the relevant Maximum Admissible Concentration (MAC) for soils. The leaching test revealed that approximately half of each pollutant was presented as a reducible fraction as well as the ferric iron in horizon A was presented mainly as minerals with amorphous structure. So, the approach for remediation of the AMD-affected soils was based on the process of redoxolysis carried out by iron-reducing bacteria. Ferric iron hydroxides reduction and the heavy metals released into soil solutions was studied in the dependence on the source of organic (fresh or silage hay) which was used for growth and activity of soil microflora, initial soil pH (3.65; 4.2; and 5.1), and the ion content of irrigation solutions. The combination of limestone (2.0 g/ kg soil), silage addition (at rate of 45 g dry weight/ kg soil) in the beginning and reiterated at 6 month since the start of soil remediation, and periodical soil irrigation with slightly acidic solutions containing CaCl2 was sufficient the content of lead and arsenic in horizon A to be decreased to concentrations similar to the relevant MAC. The reducible, exchangeable, and carbonate mobile fractions were phases from which the pollutants was leached during the applied soil remediation. It determined the higher reduction of the pollutants bioavailability also as well as the process of ferric iron reduction was combined with neutralization of the soil acidity to pH (H2O) 6.2.

Source and fate of inorganic soil contamination around the abandoned Phillips sulfide mine, hudson Highlands, New York

USGS Publications Warehouse

Gilchrist, S.; Gates, A.; Elzinga, E.; Gorring, M.; Szabo, Z.

2011-01-01

The abandoned Phillips sulfide mine in the critical Highlands watershed in New York has been shown to produce strongly acidic mine drainage (AMD) with anomalous metal contaminants in first-order streams that exceeded local water standards by up to several orders of magnitude (Gilchrist et al., 2009). The metal-sulfide-rich tailings also produce contaminated soils with pH < 4, organic matter < 2.5% and trace metals sequestered in soil oxides. A geochemical transect to test worst-case soil contamination showed that Cr, Co and Ni correlated positively with Mn, (r = 0.72, r= 0.89, r = 0.80, respectively), suggesting Mn-oxide sequestration and that Cu and Pb correlated with Fe (r = 0.76, r = 0.83, respectively), suggesting sequestration in goethite. Ubiquitous, yellow coating on the mine wastes, including jarosite and goethite, is a carrier of the metals. Geochemical and μ-SXRF analyses determined Cu to be the major soil contaminant. μ-SXRF also demonstrated that the heterogeneous nature of the soil chemistry at the micro-meter scale is self-similar to those in the bulk soil samples. Generally metals decreased, with some fluctuations, rapidly downslope through suspension of fines and dissolution in AMD leaving the area of substantial contamination << 0.5 km from the source.

The Use of Field and Mesocosm Experiments to Quantify Effects of Physical and Chemical Stressors in Mining-Contaminated Streams.

PubMed

Cadmus, Pete; Clements, William H; Williamson, Jacob L; Ranville, James F; Meyer, Joseph S; Gutiérrez Ginés, María Jesús

2016-07-19

Identifying causal relationships between acid mine drainage (AMD) and ecological responses in the field is challenging. In addition to the direct toxicological effects of elevated metals and reduced pH, mining activities influence aquatic organisms indirectly through physical alterations of habitat. The primary goal of this research was to quantify the relative importance of physical (metal-oxide deposition) and chemical (elevated metal concentrations) stressors on benthic macroinvertebrate communities. Mesocosm experiments conducted with natural assemblages of benthic macroinvertebrates established concentration-response relationships between metals and community structure. Field experiments quantified effects of metal-oxide contaminated substrate and showed significant differences in sensitivity among taxa. To predict the recovery of dominant taxa in the field, we integrated our measures of metal tolerance and substrate tolerance with estimates of drift propensity obtained from the literature. Our estimates of recovery were consistent with patterns observed at downstream recovery sites in the NFCC, which were dominated by caddisflies and baetid mayflies. We conclude that mesocosm and small-scale field experiments, particularly those conducted with natural communities, provide an ecologically realistic complement to laboratory toxicity tests. These experiments also control for the confounding variables associated with field-based approaches, thereby supporting causal relationships between AMD stressors and responses.

Impact of fresh tailing deposition on the evolution of groundwater hydrogeochemistry at the abandoned Manitou mine site, Quebec, Canada.

PubMed

Maqsoud, Abdelkabir; Neculita, Carmen Mihaela; Bussière, Bruno; Benzaazoua, Mostafa; Dionne, Jean

2016-05-01

The abandoned Manitou mine site has produced acid mine drainage (AMD) for several decades. In order to limit the detrimental environmental impacts of AMD, different rehabilitation scenarios were proposed and analyzed. The selected rehabilitation scenario was to use fresh tailings from the neighboring Goldex gold mine as monolayer cover and to maintain an elevated water table. In order to assess the impact of the Goldex tailing deposition on the hydrogeochemistry of the Manitou mine site, a network of 30 piezometers was installed. These piezometers were used for continuous measurement of the groundwater level, as well as for water sampling campaigns for chemical quality monitoring, over a 3-year period. Hydrochemical data were analyzed using principal component analysis. Results clearly showed the benefic impact of fresh tailing deposition on the groundwater quality around the contaminated area. These findings were also confirmed by the evolution of electrical conductivity. In addition to the improvement of the physicochemical quality of water on the Manitou mine site, new tailing deposition induced an increase of water table level. However, at this time, the Manitou reactive tailings are not completely submerged and possible oxidation might still occur, especially after ceasing of the fresh tailing deposition. Therefore, complementary rehabilitation scenarios should still be considered.

Simultaneous heavy metals removal and municipal sewage sludge dewaterability improvement in bioleaching processes by various inoculums.

PubMed

Shi, Chaohong; Zhu, Nengwu; Shang, Ru; Kang, Naixin; Wu, Pingxiao

2015-11-01

The heavy metals content and dewaterability of municipal sewage sludge (MSS) are important parameters affecting its subsequent disposal and land application. Six kinds of inoculums were prepared to examine the characteristics of heavy metals removal and MSS dewaterability improvement in bioleaching processes. The results showed that Cu, Zn and Cd bioleaching efficiencies (12 days) were 81-91, 87-93 and 81-89%, respectively, which were significantly higher than those of Fe-S control (P < 0.05) and blank control (P < 0.01). The bioleaching boosted by the prepared inoculums could also significantly enhance MSS dewaterability (P < 0.01). The centrifugal dehydration efficiency of MSS rose from 73.00 to 90.00% at day 12. Microscopic observations and energy dispersive spectrum analysis demonstrated that the dewaterability improvement might be attributed to the changes of sludge structure from flocculent to obvious granular and the formation of secondary minerals mainly consisting of iron, oxygen and sulfur elements. The results above demonstrated that bacterial consortium enriched from acid mine drainage (AMD) was suitable to boost sludge bioleaching for heavy metals removal and dewaterability improvement. It also suggested that the synergy of sulfur/ferrous-oxidizing bacteria (SFOB) enriched from AMD and the cooperation of exogenous and indigenous SFOB significantly promoted bioleaching efficiencies.

Bacterially Mediated Breakdown of Cinnabar and Metacinnabar and Environmental Implications

NASA Astrophysics Data System (ADS)

Jew, A. D.; Rogers, S. B.; Rytuba, J.; Spormann, A. M.; Brown, G. E.

2006-12-01

Mercury in the forms of cinnabar (α-HgS) and metacinnabar (β-HgS) is considered by the EPA to be unreactive and of little environmental concern because of their relatively low solubilities. To determine if this current belief is valid, a consortium of bacteria (including a Thiomonas intermedia-like bacterium) was taken from the acid mine drainage (AMD) pond at the New Idria Hg Mine, San Benito Co., CA, and inoculated into filter-sterilized AMD pond water containing either ground cinnabar or metacinnabar crystals (<45μm in diameter), with sampling occurring approximately every 3 days. Under aerobic conditions the samples showed a pronounced increase in aqueous Hg concentration over background water concentrations (390(±20)ng/L). Bacteria growing on α-HgS increased the Hg concentration to 297(±10)μg/L, while bacteria growing on β-HgS resulted in levels of 4.6(±0.2)mg/L; both maxima occurred at 18 days incubation. Experiments conducted with (1) α-HgS or β-HgS in the presence of killed bacteria (anaerobic), (2) α-HgS with pond water (abiotic), and (3) β-HgS with pond water (abiotic) showed drops in aqueous Hg to below the detection limit (0.1ng/L) within 12 days. Anaerobic growth of the bacterial consortium showed a pattern similar to those of the water and HgS experiments, except that Hg levels dropped below detection limit within 6 days. These combined results suggest that HgS degradation by this bacterial consortium is an aerobic process. Killed bacteria incubated aerobically showed a slight increase in Hg levels over background water levels (<10x increase) then dropped below detection limit. This observation suggests that enzymes might be involved in the dissolution of HgS and were still viable for ~6 days after sterilization. The New Idria AMD pond consists of an inlet stream and an outlet pipe, separated from each other by ~3m. The Hg concentration in the ferrihydrite-rich sediments at the inlet is 37mg/kg, dry weight, while the concentration at the outlet is 216mg/kg, dry weight. Surface water concentrations of Hg at the AMD pond are generally <100μg/L, suggesting that the sediments sequester Hg. During the wet season (October- March), the AMD pond receives considerable amounts of run-off from precipitation, which flushes Hg associated with ferrihydrite out of the region into the San Joaquin river s stem, representing a possible mode of Hg transport out of the New Idria Hg mining district.

The reduction of serum soluble Flt-1 in patients with neovascular age-related macular degeneration.

PubMed

Uehara, Hironori; Mamalis, Christina; McFadden, Molly; Taggart, Michael; Stagg, Brian; Passi, Samuel; Earle, Phillip; Chakravarthy, Usha; Hogg, Ruth E; Ambati, Balamurali K

2015-01-01

To evaluate serum soluble Flt-1 (sFlt-1) in age-related macular degeneration (AMD) patients. Case-control study. Study involved 56 non-AMD participants, 53 early AMD patients, and 97 neovascular AMD patients from Belfast in Northern Ireland. Serum samples were collected from each patient. Serum sFlt-1 was measured by human sVEGFR1/sFlt-1 ELISA kit. The results were analyzed by Excel and SPSS. Serum sFlt-1 concentration of non-AMD, early AMD, and neovascular AMD were 90.8 ± 2.9 pg/mL (± standard error of the mean), 88.2 ± 2.6 pg/mL, and 79.9 ± 2.2 pg/mL. sFlt-1 from neovascular AMD patients was significantly decreased compared to non-AMD and early AMD patients (ANOVA, P < .01). For each 10-point increase in sFlt-1, the odds for having neovascular AMD compared with non-AMD and neovascular AMD decrease by 27.8%, odds ratio (OR) = 0.722 (95% confidence interval [CI]: 0.588-0.888, P = .002) and 27.0%, OR = 0.730 (95% CI: 0.594-0.898, P = .003), respectively. In patients over 73 years of age, serum sFlt-1 <80 pg/mL was associated with a >6-fold higher risk of neovascular AMD. Reduced serum sFlt-1 differentiates those patients with neovascular AMD from both early AMD and non-AMD participants. In those aged over 73, serum sFlt <80 pg/mL seems to indicate a particularly high risk of neovascular AMD. Our results indicate serum sFlt-1 could be a biomarker for development of neovascular AMD. Copyright © 2015 Elsevier Inc. All rights reserved.

Understanding Cu release into environment from Kure massive sulfide ore deposits, Kastamonu, NW Turkey

NASA Astrophysics Data System (ADS)

Demirel, Cansu; Sonmez, Seref; Balci, Nurgul

2014-05-01

Covering a wide range on the earth's crust, oxidation of metal sulfide minerals have vital environmental impacts on the aquatic environment, causing one of the major environmental problems known as acid mine drainage (AMD). Located in the Kastamonu province of the Western Black Sea region, Kure district is one of the major copper mining sites in Turkey. Mining activities in the area heads back to ancient times, such that operation is thought to be started with the Roman Empire. Currently, only the underground mining tunnels of Bakibaba and Asikoy are being operated. Thus, mining heaps and ores of those pyritic deposits have been exposed to the oxidative conditions for so long. As a result of weathering processes of past and recent heaps of the Kure volcanic massive sulfide deposits in addition to the main ore mineral (chalcopyrite), significant amount of metals, especially Cu, are being released into the environment creating undesirable environmental conditions. In order to elucidate Cu release mechanisms from Kure pyritic ore deposits and mining wastes, field and laboratory approaches were used. Surface water and sediment samples from the streams around the mining and waste sites were collected. Groundwater samples from the active underground mining site were also collected. Physical parameters (pH, Eh, T°C, and EC) of water samples were determined in situ and in the laboratory using probes (WTW pH 3110, WTW Multi 9310 and CRISON CM 35). Metal and ion concentrations of the water samples were analysed using ICP-MS and DR 2800 spectrophotometer, respectively. High Cu, Co, Zn and Fe concentrations were determined in the water samples with pH values ranging from 2.9- 4. Cu concentrions ranges from 345 ppm to 36 ppm in the water samples. Consistent with the water samples, high Cu, Fe, Zn and Co were also determined in the sediment samples. Laboratory chalcopyrite oxidation experiments under the conditions representing the field site were set up as biological and abiotic in order to elucidate Cu release from ore and wastes. Greater Cu release were measured from the biological experiments carried out with S and Fe oxidizers compared to those from the chemical experiments. Fe-oxide precipitation experiments carried out in the laboratory showed high Cu absorbtion into Fe-oxides produced by biological reactions carried out with Fe oxidizers. Overall, these preliminary experimental results showed that Cu release and migration from the source can be controlled by various microorganims which regulate S and Fe cycles in the field. Key words: Metal sulfide oxidation, Kure pyritic copper mines, AMD, Bioleaching, Secondary Fe-oxide precipitation

AdA Compiler Validation Summary Report: Certificate Number: 910920W1. 11214 Verdix Corporation, VADS VAX VMS= AMD 29K, VAda-110-03525, Version 6.04, MicroVAX 3600 (Host) to Ironics IV9001 Board (Target). MVME147 (Target)

DTIC Science & Technology

1991-09-20

Agreement Number: 91-07-16- VRX See section 3.1 for any additional information about the testing environment. As a result of this validation effort...Washington DC 20301 92-06991 AVF Control Number: AVF-VSR-511.0292 18 February 1992 91-07-16- VRX Ada COMPILER VALIDATION SUMMARY REPORT: Certificate Number...System: Ironics IV9001 board (AMD 29000) (Am29000 bare VME machine) Customer Agreement Number: 91-07-16- VRX See section 3.1 for any additional information

Nitrogen Metabolism and Growth Enhancement in Tomato Plants Challenged with Trichoderma harzianum Expressing the Aspergillus nidulans Acetamidase amdS Gene

PubMed Central

Domínguez, Sara; Rubio, M. Belén; Cardoza, Rosa E.; Gutiérrez, Santiago; Nicolás, Carlos; Bettiol, Wagner; Hermosa, Rosa; Monte, Enrique

2016-01-01

Trichoderma is a fungal genus that includes species that are currently being used as biological control agents and/or as biofertilizers. In addition to the direct application of Trichoderma spp. as biocontrol agents in plant protection, recent studies have focused on the beneficial responses exerted on plants, stimulating the growth, activating the defenses, and/or improving nutrient uptake. The amdS gene, encoding an acetamidase of Aspergillus, has been used as a selectable marker for the transformation of filamentous fungi, including Trichoderma spp., but the physiological effects of the introduction of this gene into the genome of these microorganisms still remains unexplored. No evidence of amdS orthologous genes has been detected within the Trichoderma spp. genomes and the amdS heterologous expression in Trichoderma harzianum T34 did not affect the growth of this fungus in media lacking acetamide. However, it did confer the ability for the fungus to use this amide as a nitrogen source. Although a similar antagonistic behavior was observed for T34 and amdS transformants in dual cultures against Rhizoctonia solani, Botrytis cinerea, and Fusarium oxysporum, a significantly higher antifungal activity was detected in amdS transformants against F. oxysporum, compared to that of T34, in membrane assays on media lacking acetamide. In Trichoderma-tomato interaction assays, amdS transformants were able to promote plant growth to a greater extent than the wild-type T34, although compared with this strain the transformants showed similar capability to colonize tomato roots. Gene expression patterns from aerial parts of 3-week-old tomato plants treated with T34 and the amdS transformants have also been investigated using GeneChip Tomato Genome Arrays. The downregulation of defense genes and the upregulation of carbon and nitrogen metabolism genes observed in the microarrays were accompanied by (i) enhanced growth, (ii) increased carbon and nitrogen levels, and (iii) a higher sensitivity to B. cinerea infections in plants treated with amdS transformants as detected in greenhouse assays. These observations suggest that the increased plant development promoted by the amdS transformants was at expense of defenses. PMID:27536277

Nitrogen Metabolism and Growth Enhancement in Tomato Plants Challenged with Trichoderma harzianum Expressing the Aspergillus nidulans Acetamidase amdS Gene.

PubMed

Domínguez, Sara; Rubio, M Belén; Cardoza, Rosa E; Gutiérrez, Santiago; Nicolás, Carlos; Bettiol, Wagner; Hermosa, Rosa; Monte, Enrique

2016-01-01

Trichoderma is a fungal genus that includes species that are currently being used as biological control agents and/or as biofertilizers. In addition to the direct application of Trichoderma spp. as biocontrol agents in plant protection, recent studies have focused on the beneficial responses exerted on plants, stimulating the growth, activating the defenses, and/or improving nutrient uptake. The amdS gene, encoding an acetamidase of Aspergillus, has been used as a selectable marker for the transformation of filamentous fungi, including Trichoderma spp., but the physiological effects of the introduction of this gene into the genome of these microorganisms still remains unexplored. No evidence of amdS orthologous genes has been detected within the Trichoderma spp. genomes and the amdS heterologous expression in Trichoderma harzianum T34 did not affect the growth of this fungus in media lacking acetamide. However, it did confer the ability for the fungus to use this amide as a nitrogen source. Although a similar antagonistic behavior was observed for T34 and amdS transformants in dual cultures against Rhizoctonia solani, Botrytis cinerea, and Fusarium oxysporum, a significantly higher antifungal activity was detected in amdS transformants against F. oxysporum, compared to that of T34, in membrane assays on media lacking acetamide. In Trichoderma-tomato interaction assays, amdS transformants were able to promote plant growth to a greater extent than the wild-type T34, although compared with this strain the transformants showed similar capability to colonize tomato roots. Gene expression patterns from aerial parts of 3-week-old tomato plants treated with T34 and the amdS transformants have also been investigated using GeneChip Tomato Genome Arrays. The downregulation of defense genes and the upregulation of carbon and nitrogen metabolism genes observed in the microarrays were accompanied by (i) enhanced growth, (ii) increased carbon and nitrogen levels, and (iii) a higher sensitivity to B. cinerea infections in plants treated with amdS transformants as detected in greenhouse assays. These observations suggest that the increased plant development promoted by the amdS transformants was at expense of defenses.

40 CFR Appendix A to Part 434 - Alternate Storm Limitations for Acid or Ferruginous Mine Drainage

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 30 2014-07-01 2014-07-01 false Alternate Storm Limitations for Acid or Ferruginous Mine Drainage A Appendix A to Part 434 Protection of Environment ENVIRONMENTAL...—Alternate Storm Limitations for Acid or Ferruginous Mine Drainage EC01MY92.113 ...

40 CFR Appendix A to Part 434 - Alternate Storm Limitations for Acid or Ferruginous Mine Drainage

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 31 2013-07-01 2013-07-01 false Alternate Storm Limitations for Acid or Ferruginous Mine Drainage A Appendix A to Part 434 Protection of Environment ENVIRONMENTAL...—Alternate Storm Limitations for Acid or Ferruginous Mine Drainage EC01MY92.113 ...

40 CFR Appendix A to Part 434 - Alternate Storm Limitations for Acid or Ferruginous Mine Drainage

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 30 2011-07-01 2011-07-01 false Alternate Storm Limitations for Acid or Ferruginous Mine Drainage A Appendix A to Part 434 Protection of Environment ENVIRONMENTAL... Storm Limitations for Acid or Ferruginous Mine Drainage EC01MY92.113 ...

40 CFR Appendix A to Part 434 - Alternate Storm Limitations for Acid or Ferruginous Mine Drainage

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Alternate Storm Limitations for Acid or Ferruginous Mine Drainage A Appendix A to Part 434 Protection of Environment ENVIRONMENTAL... Storm Limitations for Acid or Ferruginous Mine Drainage EC01MY92.113 ...

40 CFR Appendix A to Part 434 - Alternate Storm Limitations for Acid or Ferruginous Mine Drainage

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 31 2012-07-01 2012-07-01 false Alternate Storm Limitations for Acid or Ferruginous Mine Drainage A Appendix A to Part 434 Protection of Environment ENVIRONMENTAL...—Alternate Storm Limitations for Acid or Ferruginous Mine Drainage EC01MY92.113 ...

Assessment of the microbial community in a constructed wetland that receives acid coal mine drainage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nicomrat, D.; Dick, W.A.; Tuovinen, O.H.

2006-01-15

Constructed wetlands are used to treat acid drainage from surface or underground coal mines. However, little is known about the microbial communities in the receiving wetland cells. The purpose of this work was to characterize the microbial population present in a wetland that was receiving acid coal mine drainage (AMD). Samples were collected from the oxic sediment zone of a constructed wetland cell in southeastern Ohio that was treating acid drainage from an underground coal mine seep. Samples comprised Fe(Ill) precipitates and were pretreated with ammonium oxalate to remove interfering iron, and the DNA was extracted and purified by agarosemore » gel electrophoresis prior to amplification of portions of the 16S rRNA gene. Amplified products were separated by denaturing gradient gel electrophoresis and DNA from seven distinct bands was excised from the gel and sequenced. The sequences were matched to sequences in the GenBank bacterial 16S rDNA database. The DNA in two of the bands yielded matches with Acidithiobacillus ferrooxidans and the DNA in each of the remaining five bands was consistent with one of the following microorganisms: Acidithiobacillus thiooxidans, strain TRA3-20 (a eubacterium), strain BEN-4 (an arsenite-oxidizing bacterium), an Alcaligenes sp., and a Bordetella sp. Low bacterial diversity in these samples reflects the highly inorganic nature of the oxic sediment layer where high abundance of iron- and sulfur-oxidizing bacteria would be expected. The results we obtained by molecular methods supported our findings, obtained using culture methods, that the dominant microbial species in an acid receiving, oxic wetland are A. thiooxidans and A. ferrooxidans.« less

The fate of Mercury in Arctic regions: New understanding of atmospheric chemical processes and mercury stability in snow.

NASA Astrophysics Data System (ADS)

Steffen, A.; Ferrari, C.; Dommergue, A.; Scherz, T.; Lawson, G.; Leiatch, R.

2006-12-01

Mercury is a known toxic pollutant in the Arctic environment. Atmospheric mercury depletion events (AMDEs) have been studied in the Arctic since 1995. While advances in understanding this newly discovered cycling of mercury in the atmosphere have been made, much of the chemistry and the impact of this annually reoccurring event to the Arctic ecosystem are not well understood. Four years of continuous measurements at Alert, Canada of so-called reactive gaseous mercury (RGM) and mercury associated to particles (PHg) coupled with ongoing snow sampling have produced new information on the atmospheric chemistry and deposition of these mercury species to the Arctic. A distinct pattern during the springtime period in the distribution of these atmospheric mercury species has emerged. This pattern is characterized by the predominance of PHg concentration at the onset of the AMDEs. During the latter part of the AMDE season, there is an obvious swicth in the speciation of mercury to RGM as the main component during AMDEs. This swicth from PHg to RGM is clearly linked to a significant increase of mercury in the snow. In addition, concentrations of PHg are clearly linked with particles in the air that are primarily associated with Arctic haze. Recently, similar results have also been observed in Ny-Alesund (Svalbard). Further observations indicate that once deposited, the deposited mercury appears to evolve chemically in the snow. This change in mercury may impact the transfer of mercury to the environment during snow melt. These first time observed links between atmospheric conditions and subsequent deposition of mercury may help to ascertain the conditions throughout the Arctic as to when significant deposition of mercury will occur. It is proposed that should the concentration of atmospheric particles increase in the Arctic due to long range transport from emission sources, an increase in the deposition of mercury to this environment will increase during the springtime period. Additionally, information from these data demonstrates that the primary product of the oxidation of gaseous elemental mercury (GEM) is RGM which will associate to the particles and exist as PHg when these particles are available in the atmosphere. The oxidation of GEM is, therefore, a result of homogeneous chemistry. Results from this ongoing study and the impacts of this pollutant to the Arctic environment will be presented.

Repressed SIRT1/PGC-1α pathway and mitochondrial disintegration in iPSC-derived RPE disease model of age-related macular degeneration.

PubMed

Golestaneh, Nady; Chu, Yi; Cheng, Shuk Kei; Cao, Hong; Poliakov, Eugenia; Berinstein, Daniel M

2016-12-20

Study of age related macular degeneration (AMD) has been hampered by lack of human models that represent the complexity of the disease. Here we have developed a human in vitro disease model of AMD to investigate the underlying AMD disease mechanisms. Generation of iPSCs from retinal pigment epithelium (RPE) of AMD donors, age-matched normal donors, skin fibroblasts of a dry AMD patient, and differentiation of iPSCs into RPE (AMD RPE-iPSC-RPE, normal RPE-iPSC-RPE and AMD Skin-iPSC-RPE, respectively). Immunostaining, cell viability assay and reactive oxygen species (ROS) production under oxidative stress conditions, electron microscopy (EM) imaging, ATP production and glycogen concentration assays, quantitative real time PCR, western blot, karyotyping. The AMD RPE-iPSC-RPE and AMD Skin-iPSC-RPE present functional impairment and exhibit distinct disease phenotypes compared to RPE-iPSC-RPE generated from normal donors (Normal RPE-iPSC-RPE). The AMD RPE-iPSC-RPE and AMD Skin-iPSC-RPE show increased susceptibility to oxidative stress and produced higher levels of reactive oxygen species (ROS) under stress in accordance with recent reports. The susceptibility to oxidative stress-induced cell death in AMD RPE-iPSC-RPE and Skin-iPSC-RPE was consistent with inability of the AMD RPE-iPSC-RPE and Skin-iPSC-RPE to increase SOD2 expression under oxidative stress. Phenotypic analysis revealed disintegrated mitochondria, accumulation of autophagosomes and lipid droplets in AMD RPE-iPSC-RPE and AMD Skin-iPSC-RPE. Mitochondrial activity was significantly lower in AMD RPE-iPSC-RPE and AMD Skin-iPSC-RPE compared to normal cells and glycogen concentration was significantly increased in the diseased cells. Furthermore, Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), a regulator of mitochondrial biogenesis and function was repressed, and lower expression levels of NAD-dependent deacetylase sirtuin1 (SIRT1) were found in AMD RPE-iPSC-RPE and AMD Skin-iPSC-RPE as compared to normal RPE-iPSC-RPE. Our studies suggest SIRT1/PGC-1α as underlying pathways contributing to AMD pathophysiology, and open new avenues for development of targeted drugs for treatment of this devastating neurodegenerative disease of the visual system.

Effects of Abandoned Coal-Mine Drainage on Streamflow and Water Quality in the Mahanoy Creek Basin, Schuylkill, Columbia, and Northumberland Counties, Pennsylvania, 2001

USGS Publications Warehouse

Cravotta,, Charles A.

2004-01-01

This report assesses the contaminant loading, effects to receiving streams, and possible remedial alternatives for abandoned mine drainage (AMD) within the Mahanoy Creek Basin in east-central Pennsylvania. The Mahanoy Creek Basin encompasses an area of 157 square miles (407 square kilometers) including approximately 42 square miles (109 square kilometers) underlain by the Western Middle Anthracite Field. As a result of more than 150 years of anthracite mining in the basin, ground water, surface water, and streambed sediments have been adversely affected. Leakage from streams to underground mines and elevated concentrations (above background levels) of acidity, metals, and sulfate in the AMD from flooded underground mines and (or) unreclaimed culm (waste rock) degrade the aquatic ecosystem and impair uses of the main stem of Mahanoy Creek from its headwaters to its mouth on the Susquehanna River. Various tributaries also are affected, including North Mahanoy Creek, Waste House Run, Shenandoah Creek, Zerbe Run, and two unnamed tributaries locally called Big Mine Run and Big Run. The Little Mahanoy Creek and Schwaben Creek are the only major tributaries not affected by mining. To assess the current hydrological and chemical characteristics of the AMD and its effect on receiving streams, and to identify possible remedial alternatives, the U.S. Geological Survey (USGS) began a study in 2001, in cooperation with the Pennsylvania Department of Environmental Protection and the Schuylkill Conservation District. Aquatic ecological surveys were conducted by the USGS at five stream sites during low base-flow conditions in October 2001. Twenty species of fish were identified in Schwaben Creek near Red Cross, which drains an unmined area of 22.7 square miles (58.8 square kilometers) in the lower part of the Mahanoy Creek Basin. In contrast, 14 species of fish were identified in Mahanoy Creek near its mouth at Kneass, below Schwaben Creek. The diversity and abundance of fish species in Mahanoy Creek decreased progressively upstream from 13 species at Gowen City to only 2 species each at Ashland and Girardville. White sucker (Catostomus commersoni), a pollution-tolerant species, was present at each of the surveyed reaches. The presence of fish at Girardville was unexpected because of the poor water quality and iron-encrusted streambed at this location. Generally, macroinvertebrate diversity and abundance at these sites were diminished compared to Schwaben Creek and other tributaries draining unmined basins, consistent with the observed quality of streamwater and streambed sediment. Data on the flow rate and chemistry for 35 AMD sources and 31 stream sites throughout the Mahanoy Creek Basin were collected by the USGS during high base-flow conditions in March 2001 and low base-flow conditions in August 2001. A majority of the base-flow streamwater samples met water-quality standards for pH (6.0 to 9.0); however, few samples downstream from AMD sources met criteria for acidity less than alkalinity (net alkalinity = 20 milligrams per liter as CaCO3) and concentrations of dissolved iron (0.3 milligram per liter) and total manganese (1.0 milligram per liter). Iron, aluminum, and various trace elements including cobalt, copper, lead, nickel, and zinc, were present in many streamwater samples at concentrations at which continuous exposure can not be tolerated by aquatic organisms without an unacceptable effect. Furthermore, concentrations of sulfate, iron, manganese, aluminum, and (or) beryllium in some samples exceeded drinking-water standards. Other trace elements, including antimony, arsenic, barium, cadmium, chromium, selenium, silver, and thallium, did not exceed water-quality criteria for protection of aquatic organisms or human health. Nevertheless, when considered together, concentrations of iron, manganese, arsenic, cadmium, chromium, copper, lead, nickel, and zinc in a majority of the streambed sediment samples from Mahanoy Creek and

Specification and prediction of nickel mobilization using artificial intelligence methods

NASA Astrophysics Data System (ADS)

Gholami, Raoof; Ziaii, Mansour; Ardejani, Faramarz Doulati; Maleki, Shahoo

2011-12-01

Groundwater and soil pollution from pyrite oxidation, acid mine drainage generation, and release and transport of toxic metals are common environmental problems associated with the mining industry. Nickel is one toxic metal considered to be a key pollutant in some mining setting; to date, its formation mechanism has not yet been fully evaluated. The goals of this study are 1) to describe the process of nickel mobilization in waste dumps by introducing a novel conceptual model, and 2) to predict nickel concentration using two algorithms, namely the support vector machine (SVM) and the general regression neural network (GRNN). The results obtained from this study have shown that considerable amount of nickel concentration can be arrived into the water flow system during the oxidation of pyrite and subsequent Acid Drainage (AMD) generation. It was concluded that pyrite, water, and oxygen are the most important factors for nickel pollution generation while pH condition, SO4, HCO3, TDS, EC, Mg, Fe, Zn, and Cu are measured quantities playing significant role in nickel mobilization. SVM and GRNN have predicted nickel concentration with a high degree of accuracy. Hence, SVM and GRNN can be considered as appropriate tools for environmental risk assessment.

Thallium release from acid mine drainages: Speciation in river and tap water from Valdicastello mining district (northwest Tuscany).

PubMed

Campanella, Beatrice; Casiot, Corinne; Onor, Massimo; Perotti, Martina; Petrini, Riccardo; Bramanti, Emilia

2017-08-15

In this work we present an advantageous method for the simultaneous separation and detection of Tl(I) and Tl(III) species through ion chromatography coupled with on-line inductively coupled plasma - mass spectrometry. Chromatographic separation between Tl(III) and Tl(I) was achieved in less than two minutes. The method was validated by recovery experiments on real samples, and by comparing the sum of the concentrations of individual Tl species with total thallium values obtained from continuous flow ICP-MS. The experimental procedure offers an accurate, sensitive and interference-free method for Tl speciation at trace levels in environmental samples. This allowed us to investigate the Tl speciation in acid mine drainages (AMD), surface waters and springs in a mining catchment in Valdicastello Carducci (Tuscany, Italy), where severe Tl contamination ad been evidenced previously. This study shows for the first time that Tl(III), in addition to Tl(I), is present in considerable amounts in water samples affected by acid mining outflow, raising the question of the origin of this thermodynamically unstable species. Copyright © 2017 Elsevier B.V. All rights reserved.

Reduction of acid rock drainage using steel slag in cover systems over sulfide rock waste piles.

PubMed

de Almeida, Rodrigo Pereira; Leite, Adilson do Lago; Borghetti Soares, Anderson

2015-04-01

The extraction of gold, coal, nickel, uranium, copper and other earth-moving activities almost always leads to environmental damage. In metal and coal extraction, exposure of sulfide minerals to the atmosphere leads to generation of acid rock drainage (ARD) and in underground mining to acid mine drainage (AMD) due to contamination of infiltrating groundwater. This study proposes to develop a reactive cover system that inhibits infiltration of oxygen and also releases alkalinity to increase the pH of generated ARD and attenuate metal contaminants at the same time. The reactive cover system is constructed using steel slag, a waste product generated from steel industries. This study shows that this type of cover system has the potential to reduce some of the adverse effects of sulfide mine waste disposal on land. Geochemical and geotechnical characterization tests were carried out. Different proportions of sulfide mine waste and steel slag were studied in leachate extraction tests. The best proportion was 33% of steel slag in dry weight. Other tests were conducted as follows: soil consolidation, saturated permeability and soil water characteristic curve. The cover system was numerically modeled through unsaturated flux analysis using Vadose/w. The solution proposed is an oxygen transport barrier that allows rain water percolation to treat the ARD in the waste rock pile. The results showed that the waste pile slope is an important factor and the cover system must have 5 m thickness to achieve an acceptable effectiveness. © The Author(s) 2015.

Tumor necrosis factor-alpha potentiates the cytotoxicity of amiodarone in Hepa1c1c7 cells: roles of caspase activation and oxidative stress.

PubMed

Lu, Jingtao; Miyakawa, Kazuhisa; Roth, Robert A; Ganey, Patricia E

2013-01-01

Amiodarone (AMD), a class III antiarrhythmic drug, causes idiosyncratic hepatotoxicity in human patients. We demonstrated previously that tumor necrosis factor-alpha (TNF-α) plays an important role in a rat model of AMD-induced hepatotoxicity under inflammatory stress. In this study, we developed a model in vitro to study the roles of caspase activation and oxidative stress in TNF potentiation of AMD cytotoxicity. AMD caused cell death in Hepa1c1c7 cells, and TNF cotreatment potentiated its toxicity. Activation of caspases 9 and 3/7 was observed in AMD/TNF-cotreated cells, and caspase inhibitors provided minor protection from cytotoxicity. Intracellular reactive oxygen species (ROS) generation and lipid peroxidation were observed after treatment with AMD and were further elevated by TNF cotreatment. Adding water-soluble antioxidants (trolox, N-acetylcysteine, glutathione, or ascorbate) produced only minor attenuation of AMD/TNF-induced cytotoxicity and did not influence the effect of AMD alone. On the other hand, α-tocopherol (TOCO), which reduced lipid peroxidation and ROS generation, prevented AMD toxicity and caused pronounced reduction in cytotoxicity from AMD/TNF cotreatment. α-TOCO plus a pancaspase inhibitor completely abolished AMD/TNF-induced cytotoxicity. In summary, activation of caspases and oxidative stress were observed after AMD/TNF cotreatment, and caspase inhibitors and a lipid-soluble free-radical scavenger attenuated AMD/TNF-induced cytotoxicity.

Tumor Necrosis Factor-alpha Potentiates the Cytotoxicity of Amiodarone in Hepa1c1c7 Cells: Roles of Caspase Activation and Oxidative Stress

PubMed Central

Ganey, Patricia E.

2013-01-01

Amiodarone (AMD), a class III antiarrhythmic drug, causes idiosyncratic hepatotoxicity in human patients. We demonstrated previously that tumor necrosis factor-alpha (TNF-α) plays an important role in a rat model of AMD-induced hepatotoxicity under inflammatory stress. In this study, we developed a model in vitro to study the roles of caspase activation and oxidative stress in TNF potentiation of AMD cytotoxicity. AMD caused cell death in Hepa1c1c7 cells, and TNF cotreatment potentiated its toxicity. Activation of caspases 9 and 3/7 was observed in AMD/TNF-cotreated cells, and caspase inhibitors provided minor protection from cytotoxicity. Intracellular reactive oxygen species (ROS) generation and lipid peroxidation were observed after treatment with AMD and were further elevated by TNF cotreatment. Adding water-soluble antioxidants (trolox, N-acetylcysteine, glutathione, or ascorbate) produced only minor attenuation of AMD/TNF-induced cytotoxicity and did not influence the effect of AMD alone. On the other hand, α-tocopherol (TOCO), which reduced lipid peroxidation and ROS generation, prevented AMD toxicity and caused pronounced reduction in cytotoxicity from AMD/TNF cotreatment. α-TOCO plus a pancaspase inhibitor completely abolished AMD/TNF-induced cytotoxicity. In summary, activation of caspases and oxidative stress were observed after AMD/TNF cotreatment, and caspase inhibitors and a lipid-soluble free-radical scavenger attenuated AMD/TNF-induced cytotoxicity. PMID:23042730

Short-range correlation in high-momentum antisymmetrized molecular dynamics

NASA Astrophysics Data System (ADS)

Myo, Takayuki

2018-03-01

We propose a new variational method for treating short-range repulsion of bare nuclear force for nuclei in antisymmetrized molecular dynamics (AMD). In AMD, the short-range correlation is described in terms of large imaginary centroids of Gaussian wave packets of nucleon pairs in opposite signs, causing high-momentum components in the nucleon pairs. We superpose these AMD basis states and call this method "high-momentum AMD" (HM-AMD), which is capable of describing the strong tensor correlation [T. Myo et al., Prog. Theor. Exp. Phys., 2017, 111D01 (2017)]. In this letter, we extend HM-AMD by including up to two kinds of nucleon pairs in each AMD basis state utilizing the cluster expansion, which produces many-body correlations involving high-momentum components. We investigate how well HM-AMD describes the short-range correlation by showing the results for ^3H using the Argonne V4^' central potential. It is found that HM-AMD reproduces the results of few-body calculations and also the tensor-optimized AMD. This means that HM-AMD is a powerful approach to describe the short-range correlation in nuclei. In HM-AMD, the momentum directions of nucleon pairs isotropically contribute to the short-range correlation, which is different from the tensor correlation.

Interferon gamma-inducible protein-10 (IP-10) and eotaxin as biomarkers in age-related macular degeneration.

PubMed

Mo, Fong Ming; Proia, Alan D; Johnson, Walter H; Cyr, Desiree; Lashkari, Kameran

2010-08-01

To analyze serum cytokine levels in subjects with different stages of AMD and to study the expression of salient cytokines in postmortem eyes with AMD. A suspension array system was used to analyze sera (n = 18 to 20/group) from control subjects and those with early AMD (AREDS stage 1), intermediate dry AMD (AREDS stage 3), advanced AMD with geographic atrophy (GA), or neovascular AMD (CNV). Postmortem eyes with AMD or control eyes were examined immunohistochemically for expression of IP-10 and eotaxin (n = 4 to 8/group). Serum eotaxin and IP-10 levels were significantly elevated in all stages of AMD, except for eotaxin levels in neovascular AMD (P < 0.07). The peak of serum IP-10 concentration was at intermediate dry AMD. In donor eyes, IP-10 and eotaxin expressions were increased in the RPE of eyes with early AMD, GA, and CNV. Eotaxin accumulated within the layer of basal linear/laminar deposits in all stages of AMD, while IP-10 was mainly in eyes with GA and CNV. IP-10 was abundant in the connective tissue matrix associated with CNV, and eotaxin was usually present but more focally and with less intense staining. Both IP-10 and eotaxin were expressed by neovascular endothelial cells. Both IP-10 and eotaxin were expressed in the neurosensory retina, but there was no detectable difference in staining between eyes with or without AMD. IP-10 and eotaxin may be early biomarkers in AMD. The authors hypothesize that the relative balance between levels of IP-10 and eotaxin is critical in regulating the neovascular response.

Evaluation of engineering properties for the use of leached brown coal ash in soil covers.

PubMed

Mudd, Gavin M; Chakrabarti, Srijib; Kodikara, Jayantha

2007-01-31

The need to engineer cover systems for the successful rehabilitation or remediation of a wide variety of solid wastes is increasing. Some common applications include landfills, hazardous waste repositories, or mine tailings dams and waste rock/overburden dumps. The brown coal industry of the Latrobe Valley region of Victoria, Australia, produces significant quantities of coal ash and overburden annually. There are some site-specific acid mine drainage (AMD) issues associated with overburden material. This needs to be addressed both during the operational phase of a project and during rehabilitation. An innovative approach was taken to investigate the potential to use leached brown coal ash in engineered soil covers on this overburden dump. The basis for this is two-fold: first, the ash has favourable physical characteristics for use in cover systems (such as high storage capacity/porosity, moderately low permeability, and an ability to act as a capillary break layer generating minimal leachate or seepage); and second, the leachate from the ash is mildly alkaline (which can help to mitigate and reduce the risk of AMD). This paper will review the engineering issues involved in using leached brown coal ash in designing soil covers for potentially acid-forming overburden dumps. It presents the results of laboratory work investigating the technical feasibility of using leached brown coal ash in engineered solid waste cover systems.

Efficient inhibition of heavy metal release from mine tailings against acid rain exposure by triethylenetetramine intercalated montmorillonite (TETA-Mt).

PubMed

Gong, Beini; Wu, Pingxiao; Huang, Zhujian; Li, Yuanyuan; Yang, Shanshan; Dang, Zhi; Ruan, Bo; Kang, Chunxi

2016-11-15

The potential application of triethylenetetramine intercalated montmorillonite (TETA-Mt) in mine tailings treatment and AMD (acid mine drainage) remediation was investigated with batch experiments. The structural and morphological characteristics of TETA-Mt were analyzed with XRD, FTIR, DTG-TG and SEM. The inhibition efficiencies of TETA-Mt against heavy metal release from mine tailings when exposed to acid rain leaching was examined and compared with that of triethylenetetramine (TETA) and Mt. Results showed that the overall inhibition by TETA-Mt surpassed that by TETA or Mt for various heavy metal ions over an acid rain pH range of 3-5.6 and a temperature range of 25-40°C. When mine tailings were exposed to acid rain of pH 4.8 (the average rain pH of the mining site where the mine tailings were from), TETA-Mt achieved an inhibition efficiency of over 90% for Cu(2+), Zn(2+), Cd(2+) and Mn(2+) release, and 70% for Pb(2+) at 25°C. It was shown that TETA-Mt has a strong buffering capacity. Moreover, TETA-Mt was able to adsorb heavy metal ions and the adsorption process was fast, suggesting that coordination was mainly responsible. These results showed the potential of TETA-Mt in AMD mitigation, especially in acid rain affected mining area. Copyright © 2016 Elsevier B.V. All rights reserved.

Figure ground discrimination in age-related macular degeneration.

PubMed

Tran, Thi Ha Chau; Guyader, Nathalie; Guerin, Anne; Despretz, Pascal; Boucart, Muriel

2011-03-01

To investigate impairment in discriminating a figure from its background and to study its relation to visual acuity and lesion size in patients with neovascular age-related macular degeneration (AMD). Seventeen patients with neovascular AMD and visual acuity <20/50 were included. Seventeen age-matched healthy subjects participated as controls. Complete ophthalmologic examination was performed on all participants. The stimuli were photographs of scenes containing animals (targets) or other objects (distractors), displayed on a computer monitor screen. Performance was compared in four background conditions: the target in the natural scene; the target isolated on a white background; the target separated by a white space from a structured scene; the target separated by a white space from a nonstructured, shapeless background. Target discriminability (d') was recorded. Performance was lower for patients than for controls. For the patients, it was easier to detect the target when it was separated from its background (under isolated, structured, and nonstructured conditions) than it was when located in a scene. Performance was improved in patients with increasing exposure time but remained lower in controls. Correlations were found between visual acuity, lesion size, and sensitivity for patients. Figure/ground segregation is impaired in patients with AMD. A white space surrounding an object is sufficient to improve the object's detection and to facilitate figure/ground segregation. These results may have practical applications to the rehabilitation of the environment in patients with AMD.

Apolipoprotein E promotes subretinal mononuclear phagocyte survival and chronic inflammation in age-related macular degeneration.

PubMed

Levy, Olivier; Calippe, Bertrand; Lavalette, Sophie; Hu, Shulong J; Raoul, William; Dominguez, Elisa; Housset, Michael; Paques, Michel; Sahel, José-Alain; Bemelmans, Alexis-Pierre; Combadiere, Christophe; Guillonneau, Xavier; Sennlaub, Florian

2015-02-01

Physiologically, the retinal pigment epithelium (RPE) expresses immunosuppressive signals such as FAS ligand (FASL), which prevents the accumulation of leukocytes in the subretinal space. Age-related macular degeneration (AMD) is associated with a breakdown of the subretinal immunosuppressive environment and chronic accumulation of mononuclear phagocytes (MPs). We show that subretinal MPs in AMD patients accumulate on the RPE and express high levels of APOE. MPs of Cx3cr1(-/-) mice that develop MP accumulation on the RPE, photoreceptor degeneration, and increased choroidal neovascularization similarly express high levels of APOE. ApoE deletion in Cx3cr1(-/-) mice prevents pathogenic age- and stress-induced subretinal MP accumulation. We demonstrate that increased APOE levels induce IL-6 in MPs via the activation of the TLR2-CD14-dependent innate immunity receptor cluster. IL-6 in turn represses RPE FasL expression and prolongs subretinal MP survival. This mechanism may account, in part, for the MP accumulation observed in Cx3cr1(-/-) mice. Our results underline the inflammatory role of APOE in sterile inflammation in the immunosuppressive subretinal space. They provide rationale for the implication of IL-6 in AMD and open avenues toward therapies inhibiting pathogenic chronic inflammation in late AMD. © 2015 The Authors. Published under the terms of the CC BY 4.0 license.

Evaluation of Fe(II) oxidation at an acid mine drainage site using laboratory-scale reactors

NASA Astrophysics Data System (ADS)

Brown, Juliana; Burgos, William

2010-05-01

Acid mine drainage (AMD) is a severe environmental threat to the Appalachian region of the Eastern United States. The Susquehanna and Potomac River basins of Pennsylvania drain to the Chesapeake Bay, which is heavily polluted by acidity and metals from AMD. This study attempted to unravel the complex relationships between AMD geochemistry, microbial communities, hydrodynamic conditions, and the mineral precipitates for low-pH Fe mounds formed downstream of deep mine discharges, such as Lower Red Eyes in Somerset County, PA, USA. This site is contaminated with high concentrations of Fe (550 mg/L), Mn (115 mg/L), and other trace metals. At the site 95% of dissolved Fe(II) and 56% of total dissolved Fe is removed without treatment, across the mound, but there is no change in the concentration of trace metals. Fe(III) oxides were collected across the Red Eyes Fe mound and precipitates were analyzed by X-ray diffraction, electron microscopy and elemental analysis. Schwertmannite was the dominant mineral phase with traces of goethite. The precipitates also contained minor amounts of Al2O3, MgO,and P2O5. Laboratory flow-through reactors were constructed to quantify Fe(II) oxidation and Fe removal over time at terrace and pool depositional facies. Conditions such as residence time, number of reactors in sequence and water column height were varied to determine optimal conditions for Fe removal. Reactors with sediments collected from an upstream terrace oxidized more than 50% of dissolved Fe(II) at a ten hour residence time, while upstream pool sediments only oxidized 40% of dissolved Fe(II). Downstream terrace and pool sediments were only capable of oxidizing 25% and 20% of Fe(II), respectively. Fe(II) oxidation rates measured in the reactors were determined to be between 3.99 x 10-8and 1.94 x 10-7mol L-1s-1. The sediments were not as efficient for total dissolved Fe removal and only 25% was removed under optimal conditions. The removal efficiency for all sediments decreased as residence time decreased and as water column depth increased. Control reactors with Co-60 irradiated sediments showed an increase in Fe concentration as a result of dissolution of the sediments; thus, it was concluded that Fe(II) oxidation in the reactors was a result of biological processes and not abiotic oxidation. It was also concluded that Fe(II) oxidation and removal rates were dependent upon geochemical gradients (pH, Fe(II) concentration) rather than depositional facies. Fluorescent in situ hybridization was also performed on field and reactor samples to determine which microbial communities were responsible for the highest Fe(II) oxidation rates.

Gut microbiota modify risk for dietary glycemia-induced age-related macular degeneration.

PubMed

Rowan, Sheldon; Taylor, Allen

2018-03-21

Age-related macular degeneration (AMD) is a leading cause of blindness world-wide. Although the etiology of AMD is multifactorial, diet and nutrition have strong epidemiologic associations with disease onset and progression. Recent studies indicate a role for gut microbiota in development of AMD in mouse models and in some forms of human AMD. We previously found that consuming lower glycemia diets is associated with protection against AMD in humans and switching from higher to lower glycemia diets arrests AMD phenotypes in mice. Gut microbiota populations and circulating microbial cometabolites were altered in response to dietary carbohydrates, indicating a gut-retina axis. Here we explore additional gut microbiota-AMD interactions that point toward pathogenic roles for some gut microbiota families, including Ruminococcaceae and Lachnospiraceae, and individual members of Turicibacteraceae, Clostridiaceae, and Mogibacteriaceae. We also speculate on potential mechanisms by which gut microbiota influence AMD, with the objective of devising new AMD diagnoses and treatments.

Age-Related Macular Degeneration: New Paradigms for Treatment and Management of AMD.

PubMed

Hernández-Zimbrón, Luis Fernando; Zamora-Alvarado, Ruben; Ochoa-De la Paz, Lenin; Velez-Montoya, Raul; Zenteno, Edgar; Gulias-Cañizo, Rosario; Quiroz-Mercado, Hugo; Gonzalez-Salinas, Roberto

2018-01-01

Age-related macular degeneration (AMD) is a well-characterized and extensively studied disease. It is currently considered the leading cause of visual disability among patients over 60 years. The hallmark of early AMD is the formation of drusen, pigmentary changes at the macula, and mild to moderate vision loss. There are two forms of AMD: the "dry" and the "wet" form that is less frequent but is responsible for 90% of acute blindness due to AMD. Risk factors have been associated with AMD progression, and they are taking relevance to understand how AMD develops: (1) advanced age and the exposition to environmental factors inducing high levels of oxidative stress damaging the macula and (2) this damage, which causes inflammation inducing a vicious cycle, altogether causing central vision loss. There is neither a cure nor treatment to prevent AMD. However, there are some treatments available for the wet form of AMD. This article will review some molecular and cellular mechanisms associated with the onset of AMD focusing on feasible treatments for each related factor in the development of this pathology such as vascular endothelial growth factor, oxidative stress, failure of the clearance of proteins and organelles, and glial cell dysfunction in AMD.

On the impact of different approaches to classify age-related macular degeneration: Results from the German AugUR study.

PubMed

Brandl, Caroline; Zimmermann, Martina E; Günther, Felix; Barth, Teresa; Olden, Matthias; Schelter, Sabine C; Kronenberg, Florian; Loss, Julika; Küchenhoff, Helmut; Helbig, Horst; Weber, Bernhard H F; Stark, Klaus J; Heid, Iris M

2018-06-06

While age-related macular degeneration (AMD) poses an important personal and public health burden, comparing epidemiological studies on AMD is hampered by differing approaches to classify AMD. In our AugUR study survey, recruiting residents from in/around Regensburg, Germany, aged 70+, we analyzed the AMD status derived from color fundus images applying two different classification systems. Based on 1,040 participants with gradable fundus images for at least one eye, we show that including individuals with only one gradable eye (n = 155) underestimates AMD prevalence and we provide a correction procedure. Bias-corrected and standardized to the Bavarian population, late AMD prevalence is 7.3% (95% confidence interval = [5.4; 9.4]). We find substantially different prevalence estimates for "early/intermediate AMD" depending on the classification system: 45.3% (95%-CI = [41.8; 48.7]) applying the Clinical Classification (early/intermediate AMD) or 17.1% (95%-CI = [14.6; 19.7]) applying the Three Continent AMD Consortium Severity Scale (mild/moderate/severe early AMD). We thus provide a first effort to grade AMD in a complete study with different classification systems, a first approach for bias-correction from individuals with only one gradable eye, and the first AMD prevalence estimates from a German elderly population. Our results underscore substantial differences for early/intermediate AMD prevalence estimates between classification systems and an urgent need for harmonization.

Development of Age-Related Macular Degeneration (AMD) in the Fellow Eye of Patients with AMD Treated by Treat-and-Extend Intravitreal Therapy with Aflibercept.

PubMed

Mimura, Kensuke; Matsumoto, Hidetaka; Morimoto, Masahiro; Akiyama, Hideo

2018-01-01

To evaluate the development of neovascular age-related macular degeneration (nAMD) in the fellow eye in patients with unilateral nAMD treated by a treat-and-extend (TAE) regimen with intravitreal aflibercept injections. We retrospectively studied 104 patients with treatment-naïve unilateral nAMD. We assessed best-corrected visual acuity (BCVA) and exudative changes in the treated eyes and development of nAMD in the fellow eye for 2 years. The subjects included 46 patients with typical AMD (tAMD), 44 with polypoidal choroidal vasculopathy (PCV), and 14 with retinal angiomatous proliferation (RAP). BCVA was significantly improved after the loading phase in all subtypes. Forty-six patients (44.2%) had no recurrence within 2 years after the loading phase, including 12 (26.1%) with tAMD, 23 (52.2%) with PCV, and 11 (78.6%) with RAP (p < 0.01). Eleven patients (10.6%) developed nAMD in the fellow eye within 2 years, including 4 (8.7%) with tAMD, 0 (0%) with PCV, and 7 (50.0%) with RAP (p < 0.001). Patients with RAP had significantly more frequent development of nAMD in the fellow eye compared to other subtypes, while they showed significantly less recurrence during the TAE regimen with intravitreal aflibercept injections. Development of nAMD in the fellow eye should be monitored in RAP when the injection interval is extended. © 2017 S. Karger AG, Basel.

Environmental management of acid water problems in mining areas

NASA Astrophysics Data System (ADS)

Singh, Gurdeep; Bhatnagar, Mridula; Sinha, D. K.

1990-03-01

Acid Mine Drainage (AMD) originates from the oxidation and leaching of sulphide minerals present in coal and metalliferrous ore bodies and gives rise to several environmental degradation problems. An investigation has been carried out to combat the acidic water problems. Results of this investigation indicate that application of anionic surfactant (sodium lauryl sulphate) and food preservatives (sodium benzoate and potassium sorbate) effectively abate the acid formation at low concentration levels (15-40 ppm) as tested in laboratory as well as at pilot-scale levels. Acidity, sulphate and iron concentrations are found to reduce by over 70 percent and remained low for more than three months after treatment. Thus this investigation demonstrates the management of these problems in an environmentally safe manner by controlling acid formation at its source.

Study on Spatial and Seasonal Behavior of Heavy Metals in the Abandoned Mine, Geopung Watershed, Korea

NASA Astrophysics Data System (ADS)

Pak, G.; HAN, K.; Kim, H.; Yeum, Y.; Hong, Y.; Kim, Y.; Yoon, J.

2016-12-01

Abandoned mine areas have increased the pollution problem through waste tailings, rock wastes, and acid mine drainage (AMD), all of which contain high amounts of heavy metals. They have various spatial and seasonal characteristics that can significantly affect water quality in the stream so it is important to assess these characteristics of AMD. The aim of this work is to study the characteristics of the spatial and seasonal behavior of heavy metals through the sediment and dissolved metal concentrations in the Geopung Mine Watershed, Korea. Seasonal variation of metal concentration in the stream sediment was found to be elevated during the summer than during any other seasons (at GP-5: 17.5 mg/kg for As, 7.5 mg/kg for Cd, 1,313 mg/kg for Zn). Similarly, heavy metal concentration in the water was also higher during the summer season (at GP-5: 0.283 mg/L for Cd, 2.554 mg/L for Cu, 12.354 mg/L for Zn). Moreover, the metal loadings were found to be increased during the summer season at the all of the point. The loading of Cd during this season was about 150 times higher than during the other seasons. This phenomenon is correlated with the pattern of the pH and TDS concentration at the upstream during summer. Low pH and High TDS concentrations significantly affect in-stream mechanisms which contribute to the fate and transport of metals. In addition, the concentration of spatial variation in sediment and water, most of the metal concentration decrease with distance from the tailing due to a dilution effect by the mixing of uncontaminated water and sediment. These study revealed that heavy metals in the stream coming from AMD and contaminant soil loss from the mine area are affected by physical influences such as rainfall intensity and velocity, and chemical influences such as pH.

Natural Microbial Assemblages Reflect Distinct Organismal and Functional Partitioning

NASA Astrophysics Data System (ADS)

Wilmes, P.; Andersson, A.; Kalnejais, L. H.; Verberkmoes, N. C.; Lefsrud, M. G.; Wexler, M.; Singer, S. W.; Shah, M.; Bond, P. L.; Thelen, M. P.; Hettich, R. L.; Banfield, J. F.

2007-12-01

The ability to link microbial community structure to function has long been a primary focus of environmental microbiology. With the advent of community genomic and proteomic techniques, along with advances in microscopic imaging techniques, it is now possible to gain insights into the organismal and functional makeup of microbial communities. Biofilms growing within highly acidic solutions inside the Richmond Mine (Iron Mountain, Redding, California) exhibit distinct macro- and microscopic morphologies. They are composed of microorganisms belonging to the three domains of life, including archaea, bacteria and eukarya. The proportion of each organismal type depends on sampling location and developmental stage. For example, mature biofilms floating on top of acid mine drainage (AMD) pools exhibit layers consisting of a densely packed bottom layer of the chemoautolithotroph Leptospirillum group II, a less dense top layer composed mainly of archaea, and fungal filaments spanning across the entire biofilm. The expression of cytochrome 579 (the most highly abundant protein in the biofilm, believed to be central to iron oxidation and encoded by Leptospirillum group II) is localized at the interface of the biofilm with the AMD solution, highlighting that biofilm architecture is reflected at the functional gene expression level. Distinct functional partitioning is also apparent in a biological wastewater treatment system that selects for distinct polyphosphate accumulating organisms. Community genomic data from " Candidatus Accumulibacter phosphatis" dominated activated sludge has enabled high mass-accuracy shotgun proteomics for identification of key metabolic pathways. Comprehensive genome-wide alignment of orthologous proteins suggests distinct partitioning of protein variants involved in both core-metabolism and specific metabolic pathways among the dominant population and closely related species. In addition, strain- resolved proteogenomic analysis of the AMD biofilms also highlights the importance of strain heterogeneity for the maintenance of community structure and function. These findings explain the importance of genetic diversity in facilitating the stable performance of complex microbial processes. Furthermore, although very different in terms of habitat, both microbial communities exhibit distinct functional compartmentalization and demonstrate its role in sustaining microbial community structure.

Influence of ROBO1 and RORA on risk of age-related macular degeneration reveals genetically distinct phenotypes in disease pathophysiology.

PubMed

Jun, Gyungah; Nicolaou, Michael; Morrison, Margaux A; Buros, Jacqueline; Morgan, Denise J; Radeke, Monte J; Yonekawa, Yoshihiro; Tsironi, Evangelia E; Kotoula, Maria G; Zacharaki, Fani; Mollema, Nissa; Yuan, Yang; Miller, Joan W; Haider, Neena B; Hageman, Gregory S; Kim, Ivana K; Schaumberg, Debra A; Farrer, Lindsay A; DeAngelis, Margaret M

2011-01-01

ROBO1 is a strong candidate gene for age-related macular degeneration (AMD) based upon its location under a linkage peak on chromosome 3p12, its expression pattern, and its purported function in a pathway that includes RORA, a gene previously associated with risk for neovascular AMD. Previously, we observed that expression of ROBO1 and RORA is down-regulated among wet AMD cases, as compared to their unaffected siblings. Thus, we hypothesized that contribution of association signals in ROBO1, and interaction between these two genes may be important for both wet and dry AMD. We evaluated association of 19 single nucleotide polymorphisms (SNPs) in ROBO1 with wet and dry stages of AMD in a sibling cohort and a Greek case-control cohort containing 491 wet AMD cases, 174 dry AMD cases and 411 controls. Association signals and interaction results were replicated in an independent prospective cohort (1070 controls, 164 wet AMD cases, 293 dry AMD cases). The most significantly associated ROBO1 SNPs were rs1387665 under an additive model (meta P = 0.028) for wet AMD and rs9309833 under a recessive model (meta P = 6 × 10(-4)) for dry AMD. Further analyses revealed interaction between ROBO1 rs9309833 and RORA rs8034864 for both wet and dry AMD (interaction P<0.05). These studies were further supported by whole transcriptome expression profile studies from 66 human donor eyes and chromatin immunoprecipitation assays from mouse retinas. These findings suggest that distinct ROBO1 variants may influence the risk of wet and dry AMD, and the effects of ROBO1 on AMD risk may be modulated by RORA variants.

Genetic factors of age-related macular degeneration

PubMed Central

Tuo, Jingsheng; Bojanowski, Christine M.; Chan, Chi-Chao

2007-01-01

Age-related macular degeneration (AMD) is a leading cause of blindness in the United States and developed countries. Although the etiology and pathogenesis of AMD remain unknown, a complex interaction of genetic and environmental factors is thought to exist. The incidence and progression of all of the features of AMD are known to increase significantly with age. The tendency for familial aggregation and the findings of gene variation association studies implicate a significant genetic component in the development of AMD. This review summarizes in detail the AMD-related genes identified by studies on genetically engineered and spontaneously gene-mutated (naturally mutated) animals, AMD chromosomal loci identified by linkage studies, AMD-related genes identified through studies of monogenic degenerative retinal diseases, and AMD-related gene variation identified by association studies. PMID:15094132

Polymorphisms in ARMS2/HTRA1 and Complement Genes and Age-Related Macular Degeneration in India: Findings from the INDEYE Study

PubMed Central

Sundaresan, Periasamy; Vashist, Praveen; Ravindran, Ravilla D.; Shanker, Ashwini; Nitsch, Dorothea; Nonyane, Bareng A. S.; Smeeth, Liam; Chakravarthy, Usha; Fletcher, Astrid E.

2012-01-01

Purpose. Association between genetic variants in complement factor H (CFH), factor B (CFB), component 2 (C2), and in the ARMS2/HTRA1 region with age-related macular degeneration (AMD) comes mainly from studies of European ancestry and case-control studies of late-stage disease. We investigated associations of both early and late AMD with these variants in a population-based study of people aged 60 years and older in India. Methods. Fundus images were graded using the Wisconsin Age-Related Maculopathy Grading System and participants assigned to one of four mutually exclusive stages based on the worse affected eye (0 = no AMD, 1–3 = early AMD, 4 = late AMD). Multinomial logistic regression was used to derive risk ratios (RR) accounting for sampling method and adjusting for age, sex, and study center. Results. Of 3569 participants, 53.2% had no signs of AMD, 45.6% had features of early AMD, and 1.2% had late AMD. CFH (rs1061170), C2 (rs547154), or CFB (rs438999) was not associated with early or late AMD. In the ARMS2 locus, rs10490924 was associated with both early (adjusted RR 1.22, 95% confidence interval [CI]: 1.13–1.33, P < 0.0001) and late AMD (adjusted RR 1.81, 95% CI: 1.15–2.86; P = 0.01); rs2672598 was associated only with early AMD (adjusted RR 1.12, 95% CI: 1.02–1.23; P = 0.02); rs10490923 was not associated with early or late AMD. Conclusions. Two variants in ARMS2/HTRA1 were associated with increased risk of early AMD, and for one of these, the increased risk was also evident for late AMD. The study provides new insights into the role of these variants in early stages of AMD in India. PMID:23060141

Homocysteine and risk of age-related macular degeneration: a systematic review and meta-analysis.

PubMed

Pinna, Antonio; Zaccheddu, Francesco; Boscia, Francesco; Carru, Ciriaco; Solinas, Giuliana

2018-05-01

There is still no agreement on total plasma homocysteine (tHcy) role in age-related macular degeneration (AMD), the leading cause of new blindness in industrialized countries. We performed a systematic review and meta-analysis of the published data on the correlation between tHcy and AMD. MEDLINE/PubMed and ISI Web of Sciences searches were performed according to MOOSE guidelines. Case-control studies were eligible for inclusion. Participants and controls were AMD patients and subjects without AMD. The main outcome measure was wet AMD. Homocysteine level was the main exposure variable. Data were pooled using a random-effects model. Twelve case-control studies were identified: 10 assessed wet AMD, four dry AMD, one early AMD, one late AMD, and one any AMD. As for wet AMD, there was a total of 453 cases and 514 controls. Mean tHcy was on average 1.1 μmol/l (95% confidence interval [CI] = 0.96-1.25) greater in wet AMD cases, but there was evidence of extreme between-study heterogeneity (p < 0.001, I 2  = 91.8%). In a model homogenous for age, including six wet AMD studies (214 cases, 274 controls), mean tHcy was on average 0.58 μmol/l (95% CI = 0.35-0.73) greater in the case group, a not statistically significant result (p = 0.144) associated with moderate heterogeneity (I 2  = 39.2%). Our meta-analysis indicates that there is some weak evidence that increased tHcy might be associated with wet AMD; however, this result should be interpreted cautiously, because of a marked between-study heterogeneity and the possible effect of publication bias. Future studies, preferably of cohort design, are necessary before any firm conclusions on the putative role of increased tHcy on AMD can be drawn. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Humanin G (HNG) protects age-related macular degeneration (AMD) transmitochondrial ARPE-19 cybrids from mitochondrial and cellular damage.

PubMed

Nashine, Sonali; Cohen, Pinchas; Chwa, Marilyn; Lu, Stephanie; Nesburn, Anthony B; Kuppermann, Baruch D; Kenney, M Cristina

2017-07-20

Age-related macular degeneration (AMD) ranks third among the leading causes of visual impairment with a blindness prevalence rate of 8.7%. Despite several treatment regimens, such as anti-angiogenic drugs, laser therapy, and vitamin supplementation, being available for wet AMD, to date there are no FDA-approved therapies for dry AMD. Substantial evidence implicates mitochondrial damage and retinal pigment epithelium (RPE) cell death in the pathogenesis of AMD. However, the effects of AMD mitochondria and Humanin G (HNG), a more potent variant of the mitochondrial-derived peptide (MDP) Humanin, on retinal cell survival have not been elucidated. In this study, we characterized mitochondrial and cellular damage in transmitochondrial cybrid cell lines that contain identical nuclei but possess mitochondria from either AMD or age-matched normal (Older-normal (NL)) subjects. AMD cybrids showed (1) reduced levels of cell viability, lower mtDNA copy numbers, and downregulation of mitochondrial replication/transcription genes and antioxidant enzyme genes; and (2) elevated levels of genes related to apoptosis, autophagy and ER-stress along with increased mtDNA fragmentation and higher susceptibility to amyloid-β-induced toxicity compared to NL cybrids. In AMD cybrids, HNG protected the AMD mitochondria, reduced pro-apoptosis gene and protein levels, upregulated gp130 (a component of the HN receptor complex), and increased the protection against amyloid-β-induced damage. In summary, in cybrids, damaged AMD mitochondria mediate cell death that can be reversed by HNG treatment. Our results also provide evidence of Humanin playing a pivotal role in protecting cells with AMD mitochondria. In the future, it may be possible that AMD patient's blood samples containing damaged mitochondria may be useful as biomarkers for this condition. In conclusion, HNG may be a potential therapeutic target for treatment of dry AMD, a debilitating eye disease that currently has no available treatment. Further studies are needed to establish HNG as a viable mitochondria-targeting therapy for dry AMD.

40 CFR 434.40 - Applicability; description of the alkaline mine drainage subcategory.

Code of Federal Regulations, 2012 CFR

2012-07-01

... alkaline mine drainage subcategory. 434.40 Section 434.40 Protection of Environment ENVIRONMENTAL... BPT, BAT, BCT LIMITATIONS AND NEW SOURCE PERFORMANCE STANDARDS Alkaline Mine Drainage § 434.40 Applicability; description of the alkaline mine drainage subcategory. The provisions of this subpart are...

40 CFR 434.40 - Applicability; description of the alkaline mine drainage subcategory.

Code of Federal Regulations, 2013 CFR

2013-07-01

... alkaline mine drainage subcategory. 434.40 Section 434.40 Protection of Environment ENVIRONMENTAL... BPT, BAT, BCT LIMITATIONS AND NEW SOURCE PERFORMANCE STANDARDS Alkaline Mine Drainage § 434.40 Applicability; description of the alkaline mine drainage subcategory. The provisions of this subpart are...

40 CFR 434.40 - Applicability; description of the alkaline mine drainage subcategory.

Code of Federal Regulations, 2014 CFR

2014-07-01

... alkaline mine drainage subcategory. 434.40 Section 434.40 Protection of Environment ENVIRONMENTAL... BPT, BAT, BCT LIMITATIONS AND NEW SOURCE PERFORMANCE STANDARDS Alkaline Mine Drainage § 434.40 Applicability; description of the alkaline mine drainage subcategory. The provisions of this subpart are...

40 CFR 434.40 - Applicability; description of the alkaline mine drainage subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... alkaline mine drainage subcategory. 434.40 Section 434.40 Protection of Environment ENVIRONMENTAL..., BCT LIMITATIONS AND NEW SOURCE PERFORMANCE STANDARDS Alkaline Mine Drainage § 434.40 Applicability; description of the alkaline mine drainage subcategory. The provisions of this subpart are applicable to...

40 CFR 434.40 - Applicability; description of the alkaline mine drainage subcategory.

Code of Federal Regulations, 2011 CFR

2011-07-01

... alkaline mine drainage subcategory. 434.40 Section 434.40 Protection of Environment ENVIRONMENTAL..., BCT LIMITATIONS AND NEW SOURCE PERFORMANCE STANDARDS Alkaline Mine Drainage § 434.40 Applicability; description of the alkaline mine drainage subcategory. The provisions of this subpart are applicable to...

Age-Related Macular Degeneration: New Paradigms for Treatment and Management of AMD

PubMed Central

Zamora-Alvarado, Ruben; Gulias-Cañizo, Rosario; Quiroz-Mercado, Hugo

2018-01-01

Age-related macular degeneration (AMD) is a well-characterized and extensively studied disease. It is currently considered the leading cause of visual disability among patients over 60 years. The hallmark of early AMD is the formation of drusen, pigmentary changes at the macula, and mild to moderate vision loss. There are two forms of AMD: the “dry” and the “wet” form that is less frequent but is responsible for 90% of acute blindness due to AMD. Risk factors have been associated with AMD progression, and they are taking relevance to understand how AMD develops: (1) advanced age and the exposition to environmental factors inducing high levels of oxidative stress damaging the macula and (2) this damage, which causes inflammation inducing a vicious cycle, altogether causing central vision loss. There is neither a cure nor treatment to prevent AMD. However, there are some treatments available for the wet form of AMD. This article will review some molecular and cellular mechanisms associated with the onset of AMD focusing on feasible treatments for each related factor in the development of this pathology such as vascular endothelial growth factor, oxidative stress, failure of the clearance of proteins and organelles, and glial cell dysfunction in AMD. PMID:29484106

Prospective study of plasma homocysteine level and risk of age-related macular degeneration in women.

PubMed

Christen, William G; Cook, Nancy R; Ridker, Paul M; Buring, Julie E

2015-04-01

Prospective data to examine the association of homocysteine with age-related macular degeneration (AMD) are limited. We examined the prospective relation of plasma homocysteine level and AMD in a large cohort of apparently healthy women. We evaluated the relationship between baseline levels of plasma homocysteine and incident AMD among 27,479 female health professionals aged 40 years or older. Main outcome measures were total AMD, defined as self-report documented by medical record evidence of an initial diagnosis after randomization, and visually significant AMD, defined as confirmed incident AMD with visual acuity 20/30 or worse attributable to this condition. During an average 10 years of follow-up, a total of 452 cases of AMD, including 182 cases of visually significant AMD, were documented. Women in the highest versus lowest quartile of plasma homocysteine had modestly, but statistically non-significant, increased risks of total AMD (hazard ratio, HR, 1.24, 95% confidence interval, CI, 0.95-1.63; p for trend 0.07) and visually significant AMD (HR 1.41, 95% CI 0.92-2.17; p for trend 0.052) in age- and treatment-adjusted analyses. These prospective data from a large cohort of apparently healthy women do not support a strong role for homocysteine in AMD occurrence.

ATAC-Seq analysis reveals a widespread decrease of chromatin accessibility in age-related macular degeneration.

PubMed

Wang, Jie; Zibetti, Cristina; Shang, Peng; Sripathi, Srinivasa R; Zhang, Pingwu; Cano, Marisol; Hoang, Thanh; Xia, Shuli; Ji, Hongkai; Merbs, Shannath L; Zack, Donald J; Handa, James T; Sinha, Debasish; Blackshaw, Seth; Qian, Jiang

2018-04-10

Age-related macular degeneration (AMD) is a significant cause of vision loss in the elderly. The extent to which epigenetic changes regulate AMD progression is unclear. Here we globally profile chromatin accessibility using ATAC-Seq in the retina and retinal pigmented epithelium (RPE) from AMD and control patients. Global decreases in chromatin accessibility occur in the RPE with early AMD, and in the retina of advanced disease, suggesting that dysfunction in the RPE drives disease onset. Footprints of photoreceptor and RPE-specific transcription factors are enriched in differentially accessible regions (DARs). Genes associated with DARs show altered expression in AMD. Cigarette smoke treatment of RPE cells recapitulates chromatin accessibility changes seen in AMD, providing an epigenetic link between a known risk factor for AMD and AMD pathology. Finally, overexpression of HDAC11 is partially responsible for the observed reduction in chromatin accessibility, suggesting that HDAC11 may be a potential new therapeutic target for AMD.

Fate and transport of trace metals and rare earth elements in the Snake River, an AMD/ARD-impacted watershed. Montezuma, Colorado USA.

NASA Astrophysics Data System (ADS)

McKnight, D. M.; Rue, G.

2017-12-01

Recent research in Snake River Watershed, located near the historic boomtown of Montezuma and adjacent the Continental Divide in the Colorado Rocky Mountains, has revealed the distinctive occurrence of rare earth elements (REE) at high concentrations. Here the weathering of the mineralized lithology naturally generates acid rock drainage (ARD) in addition to drainage recieved from abandoned mine adits throughout the area, results in aqueous REE concentrations three orders of magnitude higher than in most major rivers. The dominant mechanism responsible for this enrichment; their dissolution from secondary and accessory mineral stocks, abundant in REEs, promoted by the low pH waters generated from geochemical weathering of disseminated sulfide minerals. While REEs behave conservatively in acidic conditions, as well as in the presence of stabilizing ligands such as sulfate, downstream circumneutral inputs from pristine streams and a rising pH are resulting in observed fractional losses of heavy rare earth elements as well as partitioning towards colloidal and solid phases. These finding in combination with the established role of dissolved organic matter (DOM) in binding with both trace metals and REEs, suggest that competitive interactions, complexation, and scavenging are likely contributing to these proportional losses. However, outstanding questions yet remain regarding the effects of an increasing flux of trace metals as well as REEs from the Snake River Watershed into Dillon Reservoir, a major drinking water supply for the City of Denver, in part due to hydroclimatological drivers that are enhancing geochemical weathering and reducing groundwater recharge in alpine areas across the Colorado Rockies. Based on these findings also we seek to broaden this body of work to further investigate the behavior of rare earth elements (REE) in other aquatic environment as well the influence of trace metals, DOM, and pH in altering their reactivity and subsequent watershed transport.

HISTORY OF SUNLIGHT EXPOSURE IS A RISK FACTOR FOR AGE-RELATED MACULAR DEGENERATION.

PubMed

Schick, Tina; Ersoy, Lebriz; Lechanteur, Yara T E; Saksens, Nicole T M; Hoyng, Carel B; den Hollander, Anneke I; Kirchhof, Bernd; Fauser, Sascha

2016-04-01

To evaluate effects of current and past sunlight exposure and iris color on early and late age-related macular degeneration (AMD). Of 3,701 individuals from the EUGENDA database, 752 (20.3%) showed early AMD, 1,179 (31.9%) late AMD, and 1,770 (47.8%) were controls. Information about current and past sunlight exposure, former occupation type, subdivided in indoor working and outdoor working, and iris color were obtained by standardized interviewer-assisted questionnaires. Associations between environmental factors adjusted for age, gender, and smoking and early and late AMD were performed by multivariate regression analysis. Current sunlight exposure showed no association with early AMD or late AMD, but past sunlight exposure (≥8 hours outside daily) was significantly associated with early AMD (odds ratio: 5.54, 95% confidence interval 1.25-24.58, P = 0.02) and late AMD (odds ratio: 2.77, 95% confidence interval 1.25-6.16, P = 0.01). Outside working was found to be associated with late AMD (odds ratio: 2.57, 95% confidence interval 1.89-3.48, P = 1.58 × 10). No association was observed between iris color and early or late AMD. Sunlight exposure during working life is an important risk factor for AMD, whereas sunlight exposure after retirement seems to have less influence on the disease development. Therefore, preventive measures, for example, wearing sunglasses to minimize sunlight exposure, should start early to prevent development of AMD later in life.

Automatic age-related macular degeneration detection and staging

NASA Astrophysics Data System (ADS)

van Grinsven, Mark J. J. P.; Lechanteur, Yara T. E.; van de Ven, Johannes P. H.; van Ginneken, Bram; Theelen, Thomas; Sánchez, Clara I.

2013-03-01

Age-related macular degeneration (AMD) is a degenerative disorder of the central part of the retina, which mainly affects older people and leads to permanent loss of vision in advanced stages of the disease. AMD grading of non-advanced AMD patients allows risk assessment for the development of advanced AMD and enables timely treatment of patients, to prevent vision loss. AMD grading is currently performed manually on color fundus images, which is time consuming and expensive. In this paper, we propose a supervised classification method to distinguish patients at high risk to develop advanced AMD from low risk patients and provide an exact AMD stage determination. The method is based on the analysis of the number and size of drusen on color fundus images, as drusen are the early characteristics of AMD. An automatic drusen detection algorithm is used to detect all drusen. A weighted histogram of the detected drusen is constructed to summarize the drusen extension and size and fed into a random forest classifier in order to separate low risk from high risk patients and to allow exact AMD stage determination. Experiments showed that the proposed method achieved similar performance as human observers in distinguishing low risk from high risk AMD patients, obtaining areas under the Receiver Operating Characteristic curve of 0.929 and 0.934. A weighted kappa agreement of 0.641 and 0.622 versus two observers were obtained for AMD stage evaluation. Our method allows for quick and reliable AMD staging at low costs.

Rare earth and trace element signatures for assessing an impact of rock mining and processing on the environment: Wiśniówka case study, south-central Poland.

PubMed

Migaszewski, Zdzisław M; Gałuszka, Agnieszka; Dołęgowska, Sabina

2016-12-01

A detailed hydrogeochemical study was performed in the Wiśniówka mining area (south-central Poland). This covered three acid pit bodies, historic tailings acid ponds, acid pools, and additionally two neighboring rivers. All these acid mine drainage (AMD) waters are characterized by the pH in the range of 1.7 (pools) to 3.5 (tailings ponds). The most interesting is the Podwiśniówka acid pit lake that shows a very low pH (2.2-2.5) and very high concentrations of SO 4 2- (2720-5460 mg/L), Fe (545-1140 mg/L), Al (86.2 mg/L), As (9603-24,883 μg/L), Co (1317-3458 μg/L), Cr (753-2047 μg/L), Cu (6307-18,879 μg/L), Ni (1168-3127 μg/L), and rare earth element (REE) (589-1341 μg/L). In addition, seeps that drain the Podwiśniówka mine tailings and partly aggregate piles form strong acid pools in the mining area. Along with these pools, in which As and REE contents reach 369,726 and 6288 μg/L, respectively, these waters are among the most distinctive As- and REE-rich AMD surface waters across the world. It is noteworthy that the Podwiśniówka acid pit lake and Wiśniówka Duża acid pit sump exhibit different element signatures and REE concentration patterns normalized to North American Composite Shale (NASC): the Podwiśniówka acid pit lake always shows a characteristic roof-shaped medium REE (MREE) profile with distinct enrichments in Gd, Eu, and Tb whereas the other one displays a step-shaped heavy REE (HREE) profile with positive Tb and Gd anomalies. The REE undergo fractionation during weathering and the subsequent leaching of dissolved and suspended fractions from rocks to acid water bodies where these and other elements are further fractionated by geochemical processes. This study shows that the individual REE have greater affinities for Mn, HREE for Fe and SO 4 2- , and only La and Ce for Al. This specific water geochemistry has enabled us to (i) pinpoint the location of AMD "hot spots" originated from quartzite mining and processing operations conducted by current and previous mining companies, (ii) predict the directions and effects of future strip mining for quartzites in the Wiśniówka Duża and Podwiśniówka open pits, and (iii) evaluate the potential impact of mining and processing effluents on the quality of rivers.

Distribution and migration of heavy metals in soil and crops affected by acid mine drainage: Public health implications in Guangdong Province, China.

PubMed

Liao, Jianbo; Wen, Zewei; Ru, Xuan; Chen, Jundong; Wu, Haizhen; Wei, Chaohai

2016-02-01

Acid mine drainages (AMD) contain high concentrations of heavy metals, and their discharges into streams and rivers constitute serious environmental problems. This article examines the effects of AMD on soil, plant and human health at Dabaoshan mine in Guangdong Province, China. Although the large scale mining was stopped in 2011, the heavy metal pollution in soil continues to endanger crops and human health in that region. The objectives of this study were to elucidate distribution and migration of Cd, Cu, Zn, As and Pb and associated health implications to local inhabitants. We collected and analyzed 74 crop samples including 28 sugarcane, 30 vegetables, 16 paddy rice and the corresponding soil samples, used correlation and linear relationship for transformation process analysis, and applied carcinogenic and non-carcinogenic risk for hazard evaluation. Results showed that the local soils were heavily polluted with Cd, Cu and As (especially for Cd) and the mean Igeo value was as high as 3.77. Cadmium, Cu, and Zn in rice and vegetables were comparable with those found four years ago, while As and Pb in edible parts were 2 to 5 times lower than before. The root uptake of Cd and Zn contributed mainly to their high concentrations in crops due to high exchangeable fraction of soil, while leafy vegetables accumulated elevated As and Pb contents mainly due to the atmospheric deposition. Metal concentrations in sugarcane roots were higher than those in rice and vegetable roots. The risk assessment for crops consumption showed that the hazard quotients values were of 21 to 25 times higher than the threshold level for vegetables and rice, indicating a potential non-carcinogenic risk to the consumers. The estimated mean total cancer risk value of 0.0516 more than 100 times exceeded the USEPA accepted risk level of 1×10(-4), indicating unsuitability of the soil for cultivating the food crops. Therefore, the local agricultural and the land-use policies need to be reevaluated. Copyright © 2015 Elsevier Inc. All rights reserved.

Cadmium Isotope Fractionation of the Surface Waters in a Mining Area Impacted by Acid Mine Drainage

NASA Astrophysics Data System (ADS)

Yang, W.; Chen, Y.; Tang, Y.

2016-12-01

The pollution of natural waters and sediments with metals derived from acid mine drainage (AMD) is a global environmental problem. However, the processes governing the behaviors of transportation and transformation of metals like Cd in mountain area are poorly understood, the complicated hydro-geomorphic settings of mountain catchments are difficult to access . And few reports have been reported about the effects of. In this study, the concentration and the isotopic composition of Cd selected filtered stream samples from the Hengshi river affected by AMD have been determined. The Cd concentrations were determined for collected sediments samples, which cover the entire river valley from upstream to the downstream regions. Results showed that reducing concentrations for Cd were found in the river water from upstream to downstream, and also high enrichment factor for Cd in all the sediments, suggest that Cd mainly is derived from Liwu dam and easily enter into solid phase. The isotopic data show that the dissolved Cd in rivers is characterized by δ114/110Cd, ranged from 0.09 ‰ to 0.40 ‰ in term of δ114/110Cd , the mean is 0.25 ± 0.06 ‰, and the content of Cd from the sediments is 0.18 to 39.85 μg/g. The river isotope values are similar to the isotope signature of Liwu dam, which contain significant amounts of contaminants under a deep water cover, such as mine tailings, sulfide-rich rocks and minerals. Large fractionated Cd (δ114/110Cd = 0.40 ± 0.09 ‰) was found in water sample collected from midstream near a farmland, which imply there is a new source different from the LIWU dam depend on the heavier Cd signature. We hypothesize that this shift results from either hydrology changes over time in the main and tributaries stream, and some new pollution source imported. The change in the behavior of sorption of cadmium on oxides and hydroxides in the sediment system under low pH cause indistinguishable fractionation. Our result is encouraging for application of Cd isotopes as a novel tracer for identifying and tracking metal sources and attenuation mechanisms in mountain watersheds.

Comparison of different static methods for assessment of AMD generation potential in mining waste dumps in the Muteh Gold Mines, Iran.

PubMed

Mohammadi, Zohreh; Modabberi, Soroush; Jafari, Mohammad Reza; Ajayebi, Kimia Sadat

2015-06-01

Acid mine drainage (AMD) gives rise to several problems in sulfide-bearing mineral deposits whether in an ore body or in the mining wastes and tailings. Hence, several methods and parameters have been proposed to evaluate the acid-producing and acid-neutralizing potential of a material. This research compares common static methods for evaluation of acid-production potential of mining wastes in the Muteh gold mines by using 62 samples taken from six waste dumps around Senjedeh and Chah-Khatoun mines. According to a detailed mineralogical study, the waste materials are composed of mica-schist and quartz veins with a high amount of pyrite and are supposed to be susceptible to acid production, and upon a rainfall, they release acid drainage. All parameters introduced in different methods were calculated and compared in this research in order to predict the acid-generating and neutralization potential, including APP, NNP, MPA, NPR, and NAGpH. Based on the analytical results and calculation of different parameters, all methods are in a general consensus that DWS-02 and DWS-03 waste dumps are acid-forming which is clearly attributed to high content of pyrite in samples. DWS-04 is considered as non-acid forming in all methods except method 8 which is uncertain about its acid-forming potential and method 7 which considers a low potential for it. DWC-01 is acid-forming based on all methods except 8, 9, 10, and 11 which are also uncertain about its potential. The methods used are not reached to a compromise on DWS-01 and DWC-02 waste dumps. It is supposed that method 7 gives the conservationist results in all cases. Method 8 is unable to decide on some cases. It is recommended to use and rely on results provided by methods 1, 2, 3, and 12 for taking decisions for further studies. Therefore, according to the static tests used, the aforementioned criteria in selected methods can be used with much confidence as a rule of thumb estimation.

An Eye on Age-Related Macular Degeneration: The Role of MicroRNAs in Disease Pathology.

PubMed

Berber, Patricia; Grassmann, Felix; Kiel, Christina; Weber, Bernhard H F

2017-02-01

Age-related macular degeneration (AMD) is the primary cause of blindness in developed countries, and is the third leading cause worldwide. Emerging evidence suggests that beside environmental and genetic factors, epigenetic mechanisms, such as microRNA (miRNA) regulation of gene expression, are relevant to AMD providing an exciting new avenue for research and therapy. MiRNAs are short, non-coding RNAs thought to be imperative for coping with cellular stress. Numerous studies have analyzed miRNA dysregulation in AMD patients, although with varying outcomes. Four studies which profiled dysregulated circulating miRNAs in AMD yielded unique sets, and there is only minimal overlap in ocular miRNA profiling of AMD. Mouse models of AMD, including oxygen-induced retinopathy and laser-induced choroidal neovascularization, showed similarities to some extent with miRNA patterns in AMD. For example, miR-146a is an extensively researched miRNA thought to modulate inflammation, and was found to be upregulated in AMD mice and cellular systems, but also in human AMD retinae and vitreous humor. Similarly, mir-17, miR-125b and miR-155 were dysregulated in multiple AMD mouse models as well as in human AMD plasma or retinae. These miRNAs are thought to regulate angiogenesis, apoptosis, phagocytosis, and inflammation. A promising avenue of research is the modulation of such miRNAs, as the phenotype of AMD mice could be ameliorated with antagomirs or miRNA-mimic treatment. However, before meaningful strides can be made to develop miRNAs as a diagnostic or therapeutic tool, reproducible miRNA profiles need to be established for the various clinical outcomes of AMD.

Genetic association study of Age-Related Macular Degeneration in the Spanish population

PubMed Central

Brión, María; Sanchez-Salorio, Manuel; Cortón, Marta; de la Fuente, Maria; Pazos, Belen; Othman, Mohammad; Swaroop, Anand; Abecasis, Goncalo; Sobrino, Beatriz; Carracedo, Angel

2017-01-01

Purpose To investigate new genetic risk factors and replicate reported associations with advanced age related macular degeneration (AMD) in a prospective case - control study developed with a Spanish cohort. Methods Three hundred and fifty-three unrelated patients with advanced AMD (225 with atrophic AMD, 57 with neovascular AMD, and 71 with mixed AMD) and 282 age-matched controls were included. Functional and tagging SNPs in 55 candidate genes were genotyped using the SNPlex™ genotyping system. Single SNP and haplotype association analysis were performed to determine possible genetic associations; interaction effects between SNPs were also investigated. Results In agreement with previous reports, ARMS2 and CFH genes were strongly associated with AMD in the studied Spanish population. Moreover, both loci influenced risk independently giving support to different pathways implicated in AMD pathogenesis. No evidence for association of advanced AMD with other previous reported susceptibility genes, such as CST3, CX3CR1, FBLN5, HMCN1, PON1, SOD2, TLR4, VEGF and VLDLR, was detected. However, two additional genes appear to be candidate markers for the development of advanced AMD. A variant located at the 3´UTR of the FGF2 gene (rs6820411) was highly associated with atrophic AMD, and the functional SNP rs3112831 at ABCA4 showed a marginal association with the disease. Conclusion We performed a large gene association study in advanced AMD in a Spanish population. Our findings show that CFH and ARMS2 genes seem to be the principal risk loci contributing independently to AMD in our cohort. We report new significant associations that could also influence the development of advanced AMD. These findings should be confirmed in further studies with larger cohorts. PMID:21106043

Dry age-related macular degeneration: mechanisms, therapeutic targets, and imaging.

PubMed

Bowes Rickman, Catherine; Farsiu, Sina; Toth, Cynthia A; Klingeborn, Mikael

2013-12-13

Age-related macular degeneration is the leading cause of irreversible visual dysfunction in individuals over 65 in Western Society. Patients with AMD are classified as having early stage disease (early AMD), in which visual function is affected, or late AMD (generally characterized as either "wet" neovascular AMD, "dry" atrophic AMD or both), in which central vision is severely compromised or lost. Until recently, there have been no therapies available to treat the disorder(s). Now, the most common wet form of late-stage AMD, choroidal neovascularization, generally responds to treatment with anti-vascular endothelial growth factor therapies. Nevertheless, there are no current therapies to restore lost vision in eyes with advanced atrophic AMD. Oral supplementation with the Age-Related Eye Disease Study (AREDS) or AREDS2 formulation (antioxidant vitamins C and E, lutein, zeaxanthin, and zinc) has been shown to reduce the risk of progression to advanced AMD, although the impact was in neovascular rather than atrophic AMD. Recent findings, however, have demonstrated several features of early AMD that are likely to be druggable targets for treatment. Studies have established that much of the genetic risk for AMD is associated with complement genes. Consequently, several complement-based therapeutic treatment approaches are being pursued. Potential treatment strategies against AMD deposit formation and protein and/or lipid deposition will be discussed, including anti-amyloid therapies. In addition, the role of autophagy in AMD and prevention of oxidative stress through modulation of the antioxidant system will be explored. Finally, the success of these new therapies in clinical trials and beyond relies on early detection, disease typing, and predicting disease progression, areas that are currently being rapidly transformed by improving imaging modalities and functional assays.

FOUR-YEAR INCIDENCE AND PROGRESSION OF AGE-RELATED MACULAR DEGENERATION: THE LOS ANGELES LATINO EYE STUDY

PubMed Central

Varma, Rohit; Foong, Athena W.P.; Lai, Mei-Ying; Choudhury, Farzana; Klein, Ronald; Azen, Stanley P.

2011-01-01

Purpose To estimate 4-year incidence and progression of early and advanced age-related macular degeneration (AMD). Design Population-based cohort study. Methods A comprehensive ophthalmologic examination including stereoscopic fundus photography was performed on adult Latinos at baseline and follow-up. Photographs were graded using a modified Wisconsin Age-Related Maculopathy Grading System. For estimations of incidence and progression of AMD, the Age Related Eye Disease Study Scale was used. Main outcome measures are incidence and progression of early AMD (drusen type, drusen size, and retinal pigmentary abnormalities) and advanced AMD (exudative AMD and geographic atrophy). Results 4,658/6100 (76%) completed the follow-up examination. The 4-year incidence of early AMD was 7.5% (95%CI:6.6,8.4) and advanced AMD was 0.2% (95%CI:0.1,0.4). Progression of any AMD occurred in 9.3% (95%CI:8.4,10.3) of at-risk participants. Incidence and progression increased with age. Incidence of early AMD in the second eye (10.8%) was higher than incidence in the first eye (6.9%). Baseline presence of soft indistinct large drusen≥250μm in diameter was more likely to predict the 4-year incidence of pigmentary abnormalities, geographic atrophy, and exudative AMD than smaller or hard or soft distinct drusen. Conclusions Age-specific incidence and progression of AMD in Latinos are lower than in non-Hispanic whites. While incident early AMD is more often unilateral, the risk of its development in the second is higher than in the first eye. Older persons and those with soft indistinct large drusen had a higher risk of developing advanced AMD compared to those who were younger and did not have soft indistinct large drusen. PMID:20399926

Harmonizing the Classification of Age-related Macular Degeneration in the Three Continent AMD Consortium

PubMed Central

Klein, Ronald; Meuer, Stacy M.; Myers, Chelsea E.; Buitendijk, Gabriëlle H. S.; Rochtchina, Elena; Choudhury, Farzana; de Jong, Paulus T. V. M.; McKean-Cowdin, Roberta; Iyengar, Sudha K.; Gao, Xiaoyi; Lee, Kristine E.; Vingerling, Johannes R.; Mitchell, Paul; Klaver, Caroline C. W.; Wang, Jie Jin; Klein, Barbara E. K.

2014-01-01

Purpose To describe methods to harmonize the classification of age-related macular degeneration (AMD) phenotypes across four population-based cohort studies: the Beaver Dam Eye Study (BDES), Blue Mountains Eye Study (BMES), Los Angeles Latino Eye Study (LALES), and Rotterdam Study (RS). Methods AMD grading protocols, definitions of categories, and grading forms from each study were compared to determine whether there were systematic differences in AMD severity definitions and lesion categorization among the three grading centers. Each center graded the same set of 60 images using their respective systems to determine presence and severity of AMD lesions. A common five-step AMD severity scale and definitions of lesion measurement cutpoints and early and late AMD were developed from this exercise. Results Applying this severity scale changed the age-sex adjusted prevalence of early AMD from 18.7% to 20.3% in BDES, from 4.7% to 14.4% in BMES, from 14.1% to 15.8% in LALES, and from 7.5% to 17.1% in RS. Age-sex adjusted prevalences of late AMD remained unchanged. Comparison of each center’s grades of the 60 images converted to the consortium scale showed that exact agreement of AMD severity among centers varied from 61.0% to 81.4%, and one-step agreement varied from 84.7% to 98.3%. Conclusion Harmonization of AMD classification reduced categorical differences in phenotypic definitions across the studies, resulted in a new 5-step AMD severity scale, and enhanced similarity of AMD prevalence among four cohorts. Despite harmonization it may still be difficult to remove systematic differences in grading, if present. PMID:24467558

Dry Age-Related Macular Degeneration: Mechanisms, Therapeutic Targets, and Imaging

PubMed Central

Bowes Rickman, Catherine; Farsiu, Sina; Toth, Cynthia A.; Klingeborn, Mikael

2013-01-01

Age-related macular degeneration is the leading cause of irreversible visual dysfunction in individuals over 65 in Western Society. Patients with AMD are classified as having early stage disease (early AMD), in which visual function is affected, or late AMD (generally characterized as either “wet” neovascular AMD, “dry” atrophic AMD or both), in which central vision is severely compromised or lost. Until recently, there have been no therapies available to treat the disorder(s). Now, the most common wet form of late-stage AMD, choroidal neovascularization, generally responds to treatment with anti–vascular endothelial growth factor therapies. Nevertheless, there are no current therapies to restore lost vision in eyes with advanced atrophic AMD. Oral supplementation with the Age-Related Eye Disease Study (AREDS) or AREDS2 formulation (antioxidant vitamins C and E, lutein, zeaxanthin, and zinc) has been shown to reduce the risk of progression to advanced AMD, although the impact was in neovascular rather than atrophic AMD. Recent findings, however, have demonstrated several features of early AMD that are likely to be druggable targets for treatment. Studies have established that much of the genetic risk for AMD is associated with complement genes. Consequently, several complement-based therapeutic treatment approaches are being pursued. Potential treatment strategies against AMD deposit formation and protein and/or lipid deposition will be discussed, including anti-amyloid therapies. In addition, the role of autophagy in AMD and prevention of oxidative stress through modulation of the antioxidant system will be explored. Finally, the success of these new therapies in clinical trials and beyond relies on early detection, disease typing, and predicting disease progression, areas that are currently being rapidly transformed by improving imaging modalities and functional assays. PMID:24335072

Circulating vitamin D concentration and age-related macular degeneration: Systematic review and meta-analysis.

PubMed

Annweiler, Cedric; Drouet, Morgane; Duval, Guillaume T; Paré, Pierre-Yves; Leruez, Stephanie; Dinomais, Mickael; Milea, Dan

2016-06-01

Vitamin D may be involved in ocular function in older adults, but there is no current consensus on a possible association between circulating concentrations of 25-hydroxyvitamin D (25OHD) and the occurrence of age-related macular degeneration (AMD). Our objective was to systematically review and quantitatively assess the association of circulating 25OHD concentration with AMD. A Medline search was conducted in November 2015, with no date limit, using the MeSH terms "Vitamin D" OR "Vitamin D deficiency" OR "Ergocalciferols" OR 'Cholecalciferol' combined with "Age-related macular degeneration" OR "Macular degeneration" OR "Retinal degeneration" OR "Macula lutea" OR "Retina". Fixed and random-effects meta-analyses were performed to compute (i) standard mean difference in 25OHD concentration between AMD and non-AMD patients; (ii) AMD risk according to circulating 25OHD concentration. Of the 243 retrieved studies, 11 observational studies-10 cross-sectional studies and 1 cohort study-met the selection criteria. The number of participants ranged from 65 to 17,045 (52-100% women), and the number with AMD ranged from 31 to 1440. Circulating 25OHD concentration was 15% lower in AMD compared with non-AMD on average. AMD was inversely associated with the highest 25OHD quintile compared with the lowest (summary odds ratio (OR)=0.83 [95%CI:0.71-0.97]), notably late AMD (summary OR=0.47 [95%CI:0.28-0.79]). Circulating 25OHD<50nmol/L was also associated with late-stage AMD (summary OR=2.18 [95%CI:1.34-3.56]), an association that did not persist when all categories of AMD were considered (summary OR=1.26 [95%CI:0.90-1.76]). In conclusion, this meta-analysis provides evidence that high 25OHD concentrations may be protective against AMD, and that 25OHD concentrations below 50nmol/L are associated with late AMD. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Development and Validation of a Risk Score for Age-Related Macular Degeneration: The STARS Questionnaire.

PubMed

Delcourt, Cécile; Souied, Eric; Sanchez, Alice; Bandello, Francesco

2017-12-01

To develop and validate a risk score for AMD based on a simple self-administered questionnaire. Risk factors having shown the most consistent associations with AMD were included in the STARS (Simplified Théa AMD Risk-Assessment Scale) questionnaire. Two studies were conducted, one in Italy (127 participating ophthalmologists) and one in France (80 participating ophthalmologists). During 1 week, participating ophthalmologists invited all their patients aged 55 years or older to fill in the STARS questionnaire. Based on fundus examination, early AMD was defined by the presence of soft drusen and/or pigmentary abnormalities and late AMD by the presence of geographic atrophy and/or neovascular AMD. The Italian and French samples consisted of 12,639 and 6897 patients, respectively. All 13 risk factors included in the STARS questionnaire showed significant associations with AMD in the Italian sample. The area under the receiving operating characteristic curve for the STARS risk score, derived from the multivariate logistic regression in the Italian sample, was 0.78 in the Italian sample and 0.72 in the French sample. In both samples, less than 10% of patients without AMD were classified at high risk, and less than 13% of late AMD cases were classified as low risk, with a more intermediate situation in early AMD cases. STARS is a new, simple self-assessed questionnaire showing good discrimination of risk for AMD in two large European samples. It might be used by ophthalmologists in routine clinical practice or as a self-assessment for risk of AMD in the general population.

HTRA1 variant confers similar risks to geographic atrophy and neovascular age-related macular degeneration.

PubMed

Cameron, D Joshua; Yang, Zhenglin; Gibbs, Daniel; Chen, Haoyu; Kaminoh, Yuuki; Jorgensen, Adam; Zeng, Jiexi; Luo, Ling; Brinton, Eric; Brinton, Gregory; Brand, John M; Bernstein, Paul S; Zabriskie, Norman A; Tang, Shibo; Constantine, Ryan; Tong, Zongzhong; Zhang, Kang

2007-05-02

Age-related macular degeneration (AMD) is the most common cause of irreversible visual impairment in the developed world. The two forms of advanced AMD, geographic atrophy (GA) and choroidal neovascularization (wet AMD), represent two types of degenerative processes in the macula that lead to loss of central vision. Soft confluent drusen, characterized by deposits in macula without visual loss are considered a precursor of advanced AMD. A single nucleotide polymorphism, rs11200638, in the promoter of HTRA1 has been shown to increases the risk for wet AMD. However, its impact on soft confluent drusen and GA or the relationship between them is unclear. To better understand the role the HTRA1 polymorphism plays in AMD subtypes, we genotyped an expanded Utah population with 658 patients having advanced AMD or soft confluent drusen and 294 normal controls and found that the rs11200638 was significantly associated with GA. This association remains significant conditional on LOC387715 rs10490924. In addition, rs11200638 was significantly associated with soft confluent drusen, which are strongly immunolabeled with HTRA1 antibody in an AMD eye with GA similar to wet AMD. Two-locus analyses were performed for CFH Y402H variant at 1q31 and the HTRA1 polymorphism. Together CFH and HTRA1 risk variants increase the odds of having AMD by more than 40 times. These findings expand the role of HTRA1 in AMD. Understanding the underlying molecular mechanism will provide an important insight in pathogenesis of AMD.

Quantifying Fenton reaction pathways driven by self-generated H2O2 on pyrite surfaces

NASA Astrophysics Data System (ADS)

Gil-Lozano, C.; Davila, A. F.; Losa-Adams, E.; Fairén, A. G.; Gago-Duport, L.

2017-03-01

Oxidation of pyrite (FeS2) plays a significant role in the redox cycling of iron and sulfur on Earth and is the primary cause of acid mine drainage (AMD). It has been established that this process involves multi-step electron-transfer reactions between surface defects and adsorbed O2 and H2O, releasing sulfoxy species (e.g., S2O32-, SO42-) and ferrous iron (Fe2+) to the solution and also producing intermediate by-products, such as hydrogen peroxide (H2O2) and other reactive oxygen species (ROS), however, our understanding of the kinetics of these transient species is still limited. We investigated the kinetics of H2O2 formation in aqueous suspensions of FeS2 microparticles by monitoring, in real time, the H2O2 and dissolved O2 concentration under oxic and anoxic conditions using amperometric microsensors. Additional spectroscopic and structural analyses were done to track the dependencies between the process of FeS2 dissolution and the degradation of H2O2 through the Fenton reaction. Based on our experimental results, we built a kinetic model which explains the observed trend of H2O2, showing that FeS2 dissolution can act as a natural Fenton reagent, influencing the oxidation of third-party species during the long term evolution of geochemical systems, even in oxygen-limited environments.

Prevalence, racial variations, and risk factors of age-related macular degeneration in Singaporean Chinese, Indians, and Malays.

PubMed

Cheung, Chui Ming Gemmy; Li, Xiang; Cheng, Ching-Yu; Zheng, Yingfeng; Mitchell, Paul; Wang, Jie Jin; Wong, Tien Yin

2014-08-01

To describe the prevalence and risk factors for age-related macular degeneration (AMD) in a multiethnic Asian cohort of Chinese, Malay, and Indian persons. Population-based cross-sectional study. A total of 10 033 persons (3280 Malay, 3400 Indian, and 3353 Chinese; response rate, 75%) 40 years of age or older residing in Singapore. We performed comprehensive systemic and ocular examinations, retinal photography, and laboratory investigations for all participants. We graded early and late AMD signs from retinal photographs using the modified Wisconsin AMD grading scale. We calculated the age-standardized prevalence of AMD using the 2010 Singapore adult population and analyzed risk factors for AMD using logistic regression models. Early and late AMD. Of the 9799 participants with gradable photographs, 588 had early AMD and 60 had late AMD. The age-standardized prevalence was 5.1% (95% confidence interval [CI], 4.6-5.5) for early AMD and 0.5% (95% CI, 0.4-0.6) for late AMD. The prevalence of early AMD was similar between Chinese (5.7%) and Indian (4.5%; P = 0.27) persons and lower in Malays (3.5%; P = 0.002 compared with Chinese; P = 0.09 compared with Indians); in contrast, the prevalence for late AMD was similar across ethnic groups (Chinese, 0.6%; Indian, 0.3%; and Malay, 0.3%; P = 0.20). Risk factors for early AMD were older age (odds ratio [OR], 1.40 per 5-year increase in age; 95% CI, 1.33-1.47), male gender (OR, 1.81; 95% CI, 1.43-2.29), hypertension (OR, 1.28; 95% CI, 1.02-1.61), and hyperopic refraction (OR, 1.17 per 1-diopter increase in spherical equivalent; 95% CI, 1.11-1.24). Risk factors for late AMD include older age (OR, 1.87 per 5-year increase in age; 95% CI, 1.54-2.19), smoking more than 5 packs per week (OR, 3.63; 95% CI, 1.34-9.80), and presence of chronic kidney disease (OR, 2.17; 95% CI, 1.22-3.88). Early AMD is more common in Chinese and Indians than in Malays, but there were no racial variations in the prevalence of late AMD. Copyright © 2014 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Role of diet and food intake in age-related macular degeneration: a systematic review.

PubMed

Chapman, Naoko A; Jacobs, Robert J; Braakhuis, Andrea J

2018-06-21

A systematic literature review was conducted to evaluate the role of diet and food intake in age-related macular degeneration (AMD). Eighteen high-quality studies were identified. Adherence to a Mediterranean diet had decreased risk of AMD progression. An Oriental diet pattern had decreased association with AMD prevalence, whereas a Western diet pattern had increased association with AMD prevalence. High consumption of vegetables rich in carotenoids, and fatty fish containing omega-3 fatty acids was beneficial for those at risk of AMD. Vegetable oils and animal fats containing omega-6 fatty acids, and red/processed meat should be consumed minimally to reduce the risk of AMD progression. High glycaemic index diets and alcohol consumption of greater than two drinks a day had increased association with AMD. As the quality of diet and food intake had a vital role in AMD, the provision of appropriate nutritional advice to those at risk of AMD is recommended. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Inferring diagnosis and trajectory of wet age-related macular degeneration from OCT imagery of retina

NASA Astrophysics Data System (ADS)

Irvine, John M.; Ghadar, Nastaran; Duncan, Steve; Floyd, David; O'Dowd, David; Lin, Kristie; Chang, Tom

2017-03-01

Quantitative biomarkers for assessing the presence, severity, and progression of age-related macular degeneration (AMD) would benefit research, diagnosis, and treatment. This paper explores development of quantitative biomarkers derived from OCT imagery of the retina. OCT images for approximately 75 patients with Wet AMD, Dry AMD, and no AMD (healthy eyes) were analyzed to identify image features indicative of the patients' conditions. OCT image features provide a statistical characterization of the retina. Healthy eyes exhibit a layered structure, whereas chaotic patterns indicate the deterioration associated with AMD. Our approach uses wavelet and Frangi filtering, combined with statistical features that do not rely on image segmentation, to assess patient conditions. Classification analysis indicates clear separability of Wet AMD from other conditions, including Dry AMD and healthy retinas. The probability of correct classification of was 95.7%, as determined from cross validation. Similar classification analysis predicts the response of Wet AMD patients to treatment, as measured by the Best Corrected Visual Acuity (BCVA). A statistical model predicts BCVA from the imagery features with R2 = 0.846. Initial analysis of OCT imagery indicates that imagery-derived features can provide useful biomarkers for characterization and quantification of AMD: Accurate assessment of Wet AMD compared to other conditions; image-based prediction of outcome for Wet AMD treatment; and features derived from the OCT imagery accurately predict BCVA; unlike many methods in the literature, our techniques do not rely on segmentation of the OCT image. Next steps include larger scale testing and validation.

The impact of gold mining on the Witwatersrand on the rivers and karst system of Gauteng and North West Province, South Africa

NASA Astrophysics Data System (ADS)

Durand, J. F.

2012-06-01

The Witwatersrand has been subjected to geological exploration, mining activities, parallel industrial development and associated settlement patterns over the past century. The gold mines brought with them not only development, employment and wealth, but also the most devastating war in the history of South Africa, civil unrest, economical inequality, social uprooting, pollution, negative health impacts and ecological destruction. One of the most consistent and pressing problems caused by mining has been its impact on the water bodies in and adjacent to the Witwatersrand. The dewatering and rewatering of the karstic aquifer overlying and adjacent to the Witwatersrand Supergroup and the pollution caused by Acid Mine Drainage (AMD) are some of the most serious consequences of gold mining in South Africa and will affect the lives of many South Africans.

Plasma Protein Pentosidine and Carboxymethyllysine, Biomarkers for Age-related Macular Degeneration*

PubMed Central

Ni, Jiaqian; Yuan, Xianglin; Gu, Jiayin; Yue, Xiuzhen; Gu, Xiaorong; Nagaraj, Ram H.; Crabb, John W.

2009-01-01

Age-related macular degeneration (AMD) causes severe vision loss in the elderly; early identification of AMD risk could help slow or prevent disease progression. Toward the discovery of AMD biomarkers, we quantified plasma protein Nε-carboxymethyllysine (CML) and pentosidine from 58 AMD and 32 control donors. CML and pentosidine are advanced glycation end products that are abundant in Bruch membrane, the extracellular matrix separating the retinal pigment epithelium from the blood-bearing choriocapillaris. We measured CML and pentosidine by LC-MS/MS and LC-fluorometry, respectively, and found higher mean levels of CML (∼54%) and pentosidine (∼64%) in AMD (p < 0.0001) relative to normal controls. Plasma protein fructosyl-lysine, a marker of early glycation, was found by amino acid analysis to be in equal amounts in control and non-diabetic AMD donors, supporting an association between AMD and increased levels of CML and pentosidine independent of other diseases like diabetes. Carboxyethylpyrrole (CEP), an oxidative modification from docosahexaenoate-containing lipids and also abundant in AMD Bruch membrane, was elevated ∼86% in the AMD cohort, but autoantibody titers to CEP, CML, and pentosidine were not significantly increased. Compellingly higher mean levels of CML and pentosidine were present in AMD plasma protein over a broad age range. Receiver operating curves indicate that CML, CEP adducts, and pentosidine alone discriminated between AMD and control subjects with 78, 79, and 88% accuracy, respectively, whereas CML in combination with pentosidine provided ∼89% accuracy, and CEP plus pentosidine provided ∼92% accuracy. Pentosidine levels appeared slightly altered in AMD patients with hypertension and cardiovascular disease, indicating further studies are warranted. Overall this study supports the potential utility of plasma protein CML and pentosidine as biomarkers for assessing AMD risk and susceptibility, particularly in combination with CEP adducts and with concurrent analyses of fructosyl-lysine to detect confounding factors. PMID:19435712

Autophagy regulating kinases as potential therapeutic targets for age-related macular degeneration.

PubMed

Kaarniranta, Kai; Kauppinen, Anu; Blasiak, Janusz; Salminen, Antero

2012-11-01

Age-related macular degeneration (AMD) is the leading cause of central vision loss in the elderly in the developed countries. The number of AMD patients will double during the next decades due to increasing number of aged people. Chronic oxidative stress, inflammation and accumulation of protein-rich deposits both in the retinal pigment epithelium lysosomes and under the retinal pigment epithelium herald the onset of AMD. The disease can be divided into dry and wet AMD forms. The dry form of the disease is more prevalent accounting for up to 90% of all cases. Continued intraocular injections are the current treatment strategy to prevent progression of wet AMD. It is a major challenge to develop new drugs that could prevent or at least ease the symptoms of the increasing population of AMD patients. Since AMD pathology is clearly associated with accumulated protein deposits, the autophagy clearance system might represent a potential future therapeutic target for AMD as is thoroughly discussed here.

Spatio-temporal variation of anthropogenic marine debris on Chilean beaches.

PubMed

Hidalgo-Ruz, Valeria; Honorato-Zimmer, Daniela; Gatta-Rosemary, Magdalena; Nuñez, Paloma; Hinojosa, Iván A; Thiel, Martin

2018-01-01

We examined the hypothesis that in an emerging economy such as Chile the abundances of Anthropogenic Marine Debris (AMD) on beaches are increasing over time. The citizen science program Científicos de la Basura ("Litter Scientists") conducted three national surveys (2008, 2012 and 2016) to determine AMD composition, abundance, spatial patterns and temporal trends. AMD was found on all beaches along the entire Chilean coast. Highest percentages of AMD in all surveys were plastics and cigarette butts, which can be attributed to local sources (i.e. beach users). The Antofagasta region in northern Chile had the highest abundance of AMD compared with all other zones. Higher abundances of AMD were found at the upper stations from almost all zones. No significant tendency of increasing or decreasing AMD densities was observed during the 8years covered by our study, which suggests that economic development alone cannot explain temporal trends in AMD densities. Copyright © 2017 Elsevier Ltd. All rights reserved.

Do statins have a role in the prevention of age-related macular degeneration?

PubMed

Tsao, Sean W; Fong, Donald S

2013-04-01

Age-related macular degeneration (AMD) is a leading cause of blindness worldwide for which preventative therapies are few. Evidence suggesting shared common risk factors and mirrored pathophysiology between cardiovascular disease and AMD led to the hypothesis that hydroxymethylglutaryl-CoA reductase inhibitors (statins) could be helpful in preventing AMD. For over a decade, observational studies have repeatedly investigated this hypothesis with conflicting conclusions. Although many reports conclude that statin use has no effect on the risk of AMD, no randomized controlled trial has yet been completed. Furthermore, relatively few studies factor characteristics of statin use into their analysis. A few studies have observed an incompletely explained protective effect against drusen, a funduscopic finding associated with AMD. Although there is insufficient evidence for a preventive effect of statins on dry AMD, there does seem to be stronger evidence against any effect on the development of exudative AMD. Overall, we find that there is insufficient evidence to conclude whether statin use is helpful in preventing AMD.

[Experimental study on acid mine drainage treatment using mine tailings of Xiangsi Valley, Tongling, China].

PubMed

Zhang, Nan; Chen, Tian-Hu; Zhou, Yue-Fei; Li, Shao-Jie; Jin, Jie; Wang, Yan-Ming

2012-04-01

Mine tailings in Xiangsi Valley, Tongling, China, is a typical skarn-type tailing with high contents of carbonates. This study designed dynamic leaching experiments to investigate the efficiency of this tailing under the acid mine drainage treatment. During 80 d trial period, the physical and chemical properties of influents were fixed and the effluents were monitored. After the trial, the speciation of Fe, Cu and Zn in solid was analyzed. The results showed that during the trial period, pH value maintained above 7.5. Moreover, the concentrations of Cu, Zn, Fe ions in effluents kept below 0.1, 0.4 and 1 mg x L(-1), respectively. In addition, the permeability coefficient of experimental column kept decreasing during the experimental period (from 0.23 cm x s(-1) to 0.10 cm x s(-1)). Five-step sequential extraction method was employed to study the distribution of elements at different depths. The results showed that Cu2+, Zn2+ were removed mainly through sorption and precipitation. This study indicates that Tongling skarn mine tailings have strong acid neutralization as well as heavy metal binding capacities. Therefore, the authors suggest that this mine tailing, which used to be waste, has a potential in AMD control and treatment.

Clinical classification of age-related macular degeneration.

PubMed

Ferris, Frederick L; Wilkinson, C P; Bird, Alan; Chakravarthy, Usha; Chew, Emily; Csaky, Karl; Sadda, SriniVas R

2013-04-01

To develop a clinical classification system for age-related macular degeneration (AMD). Evidence-based investigation, using a modified Delphi process. Twenty-six AMD experts, 1 neuro-ophthalmologist, 2 committee chairmen, and 1 methodologist. Each committee member completed an online assessment of statements summarizing current AMD classification criteria, indicating agreement or disagreement with each statement on a 9-step scale. The group met, reviewed the survey results, discussed the important components of a clinical classification system, and defined new data analyses needed to refine a classification system. After the meeting, additional data analyses from large studies were provided to the committee to provide risk estimates related to the presence of various AMD lesions. Delphi review of the 9-item set of statements resulting from the meeting. Consensus was achieved in generating a basic clinical classification system based on fundus lesions assessed within 2 disc diameters of the fovea in persons older than 55 years. The committee agreed that a single term, age-related macular degeneration, should be used for the disease. Persons with no visible drusen or pigmentary abnormalities should be considered to have no signs of AMD. Persons with small drusen (<63 μm), also termed drupelets, should be considered to have normal aging changes with no clinically relevant increased risk of late AMD developing. Persons with medium drusen (≥ 63-<125 μm), but without pigmentary abnormalities thought to be related to AMD, should be considered to have early AMD. Persons with large drusen or with pigmentary abnormalities associated with at least medium drusen should be considered to have intermediate AMD. Persons with lesions associated with neovascular AMD or geographic atrophy should be considered to have late AMD. Five-year risks of progressing to late AMD are estimated to increase approximately 100 fold, ranging from a 0.5% 5-year risk for normal aging changes to a 50% risk for the highest intermediate AMD risk group. The proposed basic clinical classification scale seems to be of value in predicting the risk of late AMD. Incorporating consistent nomenclature into the practice patterns of all eye care providers may improve communication and patient care. Copyright © 2013 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Prevalence of Age-Related Macular Degeneration in Europe: The Past and the Future.

PubMed

Colijn, Johanna M; Buitendijk, Gabriëlle H S; Prokofyeva, Elena; Alves, Dalila; Cachulo, Maria L; Khawaja, Anthony P; Cougnard-Gregoire, Audrey; Merle, Bénédicte M J; Korb, Christina; Erke, Maja G; Bron, Alain; Anastasopoulos, Eleftherios; Meester-Smoor, Magda A; Segato, Tatiana; Piermarocchi, Stefano; de Jong, Paulus T V M; Vingerling, Johannes R; Topouzis, Fotis; Creuzot-Garcher, Catherine; Bertelsen, Geir; Pfeiffer, Norbert; Fletcher, Astrid E; Foster, Paul J; Silva, Rufino; Korobelnik, Jean-François; Delcourt, Cécile; Klaver, Caroline C W

2017-12-01

Age-related macular degeneration (AMD) is a frequent, complex disorder in elderly of European ancestry. Risk profiles and treatment options have changed considerably over the years, which may have affected disease prevalence and outcome. We determined the prevalence of early and late AMD in Europe from 1990 to 2013 using the European Eye Epidemiology (E3) consortium, and made projections for the future. Meta-analysis of prevalence data. A total of 42 080 individuals 40 years of age and older participating in 14 population-based cohorts from 10 countries in Europe. AMD was diagnosed based on fundus photographs using the Rotterdam Classification. Prevalence of early and late AMD was calculated using random-effects meta-analysis stratified for age, birth cohort, gender, geographic region, and time period of the study. Best-corrected visual acuity (BCVA) was compared between late AMD subtypes; geographic atrophy (GA) and choroidal neovascularization (CNV). Prevalence of early and late AMD, BCVA, and number of AMD cases. Prevalence of early AMD increased from 3.5% (95% confidence interval [CI] 2.1%-5.0%) in those aged 55-59 years to 17.6% (95% CI 13.6%-21.5%) in those aged ≥85 years; for late AMD these figures were 0.1% (95% CI 0.04%-0.3%) and 9.8% (95% CI 6.3%-13.3%), respectively. We observed a decreasing prevalence of late AMD after 2006, which became most prominent after age 70. Prevalences were similar for gender across all age groups except for late AMD in the oldest age category, and a trend was found showing a higher prevalence of CNV in Northern Europe. After 2006, fewer eyes and fewer ≥80-year-old subjects with CNV were visually impaired (P = 0.016). Projections of AMD showed an almost doubling of affected persons despite a decreasing prevalence. By 2040, the number of individuals in Europe with early AMD will range between 14.9 and 21.5 million, and for late AMD between 3.9 and 4.8 million. We observed a decreasing prevalence of AMD and an improvement in visual acuity in CNV occuring over the past 2 decades in Europe. Healthier lifestyles and implementation of anti-vascular endothelial growth factor treatment are the most likely explanations. Nevertheless, the numbers of affected subjects will increase considerably in the next 2 decades. AMD continues to remain a significant public health problem among Europeans. Copyright © 2017 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Age-related macular degeneration: economic burden and value-based medicine analysis.

PubMed

Brown, Melissa M; Brown, Gary C; Stein, Joshua D; Roth, Zachary; Campanella, Joseph; Beauchamp, George R

2005-06-01

It can be estimated that 17,100 new cases of neovascular (wet) AMD and 180,000 new cases of geographic-atrophy (dry) AMD occur in Canada annually. In addition to having a devastating effect on patients' lives, the condition causes significant adverse consequences for the economy. The deleterious effect of AMD on quality of life is markedly underestimated by ophthalmologists who treat patients with AMD, by non-ophthalmic physicians and by the public. In fact, patients with different degrees of severity of AMD have a perceived impairment of their quality of life that is 96% to 750% greater than the impairment estimated by treating ophthalmologists. Mild AMD causes a 17% decrease in the quality of life of the average patient, a decrease similar to that encountered with symptomatic human immunodeficiency virus infection or moderate cardiac angina. Moderate AMD produces a 40% decrease in quality of life, a decrease similar to that associated with permanent renal dialysis or severe cardiac angina. Very severe AMD causes a 63% decrement in quality of life, a decrease similar to that encountered with advanced prostatic cancer with uncontrollable pain or a severe stroke that leaves a person bedridden, incontinent and requiring constant nursing care. The adverse economic consequences of AMD include an annual $2.6 billion negative impact on Canada's gross domestic product. The return on investment is high for both current AMD therapies and research into new treatment modalities.

Prevalence of Undiagnosed Age-Related Macular Degeneration in Primary Eye Care.

PubMed

Neely, David C; Bray, Kevin J; Huisingh, Carrie E; Clark, Mark E; McGwin, Gerald; Owsley, Cynthia

2017-06-01

Age-related macular degeneration (AMD) is the leading cause of irreversible vision impairment in older adults in the United States, yet little is known about whether AMD is appropriately diagnosed in primary eye care. To examine the prevalence of eyes with AMD in patients seen in primary eye care clinics who purportedly have normal macular health per their medical record and the association of AMD with patient and physician characteristics. In this cross-sectional study of primary eye care practices in Birmingham, Alabama, 644 persons 60 years or older with normal macular health per medical record based on their most recent dilated comprehensive eye examination by a primary eye care ophthalmologist or optometrist were enrolled from May 1, 2009, through December 31, 2011. Data analysis was performed from May 1, 2016, through December 20, 2016. Presence of AMD as defined by the Clinical Age-Related Maculopathy Staging system based on color fundus photography and a masked grader. Types of AMD-associated lesions were noted. Patient health and physician characteristics were collected. The sample consisted of 1288 eyes from 644 participants (231 [35.9%] male and 413 [64.1%] female; mean [SD] age, 69.4 [6.1] years; 611 white [94.9%]) seen by 31 primary eye care ophthalmologists or optometrists. A total of 968 eyes (75.2%) had no AMD, in agreement with their medical record; 320 (24.8%) had AMD despite no diagnosis of AMD in the medical record. Among eyes with undiagnosed AMD, 32 (10.0%) had hyperpigmentation, 43 (13.4%) had hypopigmentation, 249 (77.8%) had small drusen, 250 (78.1%) had intermediate drusen, and 96 (30.0%) had large drusen. Undiagnosed AMD was associated with older patient age (odds ratio [OR], 1.06; 95% CI, 1.04-1.09; P < .001), male sex (age-adjusted OR, 1.39; 95% CI, 1.02-1.91; P = .04), and less than a high school education (age-adjusted OR, 2.40; 95% CI, 1.03-5.62; P = .04). Prevalence of undiagnosed AMD was not different for ophthalmologists and optometrists (age adjusted OR, 0.99; 95% CI, 0.71-1.36; P = .94). Approximately 25.0% of eyes deemed to be normal based on dilated eye examination by primary eye care physicians had macular characteristics that indicated AMD revealed by fundus photography and trained raters. A total of 30.0% of eyes with undiagnosed AMD had AMD with large drusen that would have been treatable with nutritional supplements had it been diagnosed. Improved AMD detection strategies may be needed in primary eye care as more effective treatment strategies for early AMD become available in the coming years.

Association of HTRA1 polymorphism and bilaterality in advanced age-related macular degeneration.

PubMed

Chen, Haoyu; Yang, Zhenglin; Gibbs, Daniel; Yang, Xian; Hau, Vincent; Zhao, Peiquan; Ma, Xiang; Zeng, Jiexi; Luo, Ling; Pearson, Erik; Constantine, Ryan; Kaminoh, Yuuki; Harmon, Jennifer; Tong, Zongzhong; Stratton, Charity A; Cameron, D Joshua; Tang, Shibo; Zhang, Kang

2008-02-01

Single nucleotide polymorphism (SNP), rs11200638, in the promoter of HTRA1 has recently been shown to increase the risk for AMD. In order to investigate the association of this HTRA1 polymorphism and the bilaterality of AMD, we genotyped rs11200638 in control, unilateral, and bilateral advanced AMD patients. The A allele for SNP rs11200638 in HTRA1, was significantly more prevalent in bilateral wet AMD and GA patients than in unilateral groups (p=.02 and p=.03, respectively). The homozygote odds ratios of bilateral wet AMD and GA are significantly greater than those seen in unilateral groups (twofold and threefold increase, respectively). This finding is consistent with the role of HTRA1 in AMD pathogenesis and will help aid in the clinical management and prognosis of AMD patients.

Identification of pathogenic genes and upstream regulators in age-related macular degeneration.

PubMed

Zhao, Bin; Wang, Mengya; Xu, Jing; Li, Min; Yu, Yuhui

2017-06-26

Age-related macular degeneration (AMD) is the leading cause of irreversible blindness in older individuals. Our study aims to identify the key genes and upstream regulators in AMD. To screen pathogenic genes of AMD, an integrated analysis was performed by using the microarray datasets in AMD derived from the Gene Expression Omnibus (GEO) database. The functional annotation and potential pathways of differentially expressed genes (DEGs) were further discovered by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. We constructed the AMD-specific transcriptional regulatory network to find the crucial transcriptional factors (TFs) which target the DEGs in AMD. Quantitative real time polymerase chain reaction (qRT-PCR) was performed to verify the DEGs and TFs obtained by integrated analysis. From two GEO datasets obtained, we identified 1280 DEGs (730 up-regulated and 550 down-regulated genes) between AMD and normal control (NC). After KEGG analysis, steroid biosynthesis is a significantly enriched pathway for DEGs. The expression of 8 genes (TNC, GRP, TRAF6, ADAMTS5, GPX3, FAP, DHCR7 and FDFT1) was detected. Except for TNC and GPX3, the other 6 genes in qRT-PCR played the same pattern with that in our integrated analysis. The dysregulation of these eight genes may involve with the process of AMD. Two crucial transcription factors (c-rel and myogenin) were concluded to play a role in AMD. Especially, myogenin was associated with AMD by regulating TNC, GRP and FAP. Our finding can contribute to developing new potential biomarkers, revealing the underlying pathogenesis, and further raising new therapeutic targets for AMD.

Five-year progression of unilateral age-related macular degeneration to bilateral involvement: the Three Continent AMD Consortium report

PubMed Central

Joachim, Nichole; Colijn, Johanna Maria; Kifley, Annette; Lee, Kristine E; Buitendijk, Gabriëlle H S; Klein, Barbara E K; Myers, Chelsea E; Meuer, Stacy M; Tan, Ava G; Holliday, Elizabeth G; Attia, John; Liew, Gerald; Iyengar, Sudha K; de Jong, Paulus T V M; Hofman, Albert; Vingerling, Johannes R; Mitchell, Paul; Klaver, Caroline C W; Klein, Ronald; Wang, Jie Jin

2018-01-01

Purpose To assess the 5-year progression from unilateral to bilateral age-related macular degeneration (AMD) and associated risk factors. Design Pooled data analyses of three prospective population-based cohorts, the Blue Mountains Eye Study, Beaver Dam Eye Study and Rotterdam Study. Methods Retinal photography and interview with comprehensive questionnaires were conducted at each visit of three studies. AMD was assessed following the modified Wisconsin AMD grading protocol. Progression to bilateral any (early and late) or late AMD was assessed among participants with unilateral involvement only. Factors associated with the progression were assessed using logistic regression models while simultaneously adjusting for other significant risk factors. Results In any 5-year duration, 19–28% of unilateral any AMD cases became bilateral and 27–68% of unilateral late AMD became bilateral. Factors associated with the progression to bilateral involvement of any AMD were age (per year increase, adjusted OR 1.07), carrying risk alleles of the complement factor H and age-related maculopathy susceptibility 2 genes (compared with none, OR 1.76 for 1 risk allele and OR 3.34 for 2+ risk alleles), smoking (compared with non-smokers, OR 1.64 for past and OR 1.67 for current smokers), and the presence of large drusen area or retinal pigmentary abnormalities in the first eye. Conclusion One in four to one in five unilateral any AMD cases, and up to one in two unilateral late AMD cases, progressed to bilateral in 5 years. Known AMD risk factors, including smoking, are significantly associated with the progression to bilateral involvement. PMID:28108569

Autophagy regulates death of retinal pigment epithelium cells in age-related macular degeneration.

PubMed

Kaarniranta, Kai; Tokarz, Paulina; Koskela, Ali; Paterno, Jussi; Blasiak, Janusz

2017-04-01

Age-related macular degeneration (AMD) is an eye disease underlined by the degradation of retinal pigment epithelium (RPE) cells, photoreceptors, and choriocapillares, but the exact mechanism of cell death in AMD is not completely clear. This mechanism is important for prevention of and therapeutic intervention in AMD, which is a hardly curable disease. Present reports suggest that both apoptosis and pyroptosis (cell death dependent on caspase-1) as well as necroptosis (regulated necrosis dependent on the proteins RIPK3 and MLKL, caspase-independent) can be involved in the AMD-related death of RPE cells. Autophagy, a cellular clearing system, plays an important role in AMD pathogenesis, and this role is closely associated with the activation of the NLRP3 inflammasome, a central event for advanced AMD. Autophagy can play a role in apoptosis, pyroptosis, and necroptosis, but its contribution to AMD-specific cell death is not completely clear. Autophagy can be involved in the regulation of proteins important for cellular antioxidative defense, including Nrf2, which can interact with p62/SQSTM, a protein essential for autophagy. As oxidative stress is implicated in AMD pathogenesis, autophagy can contribute to this disease by deregulation of cellular defense against the stress. However, these and other interactions do not explain the mechanisms of RPE cell death in AMD. In this review, we present basic mechanisms of autophagy and its involvement in AMD pathogenesis and try to show a regulatory role of autophagy in RPE cell death. This can result in considering the genes and proteins of autophagy as molecular targets in AMD prevention and therapy.

Identifying and Further Understanding the Role of Bacteria and Archaea in a Basic Mine Drainage Remediation Site in Tanoma, PA

NASA Astrophysics Data System (ADS)

Sharp, G.; Mount, G.

2017-12-01

Acid mine drainage pollutes over 3000 miles of streams and ground water in Pennsylvania alone, and in response many solutions have been developed to counteract the effects of acidic mine drainage. It is estimated by USGS that restoring these watersheds would cost 5 billion-15 billion in total. As economic conditions place limits on expenditures, cost effective means of remediation will be of critical importance. One such method is passive bioremediation, and in the case of metal contamination, self-sustaining oxygenation. Our location of interest is the Tanoma Acid Mine Drainage engineered wetland near Tanoma, Pennsylvania. It is estimated that up to 5,000 gallons per minute is currently being discharged into the site. While most local remediation sites are acidic (pH <4), the Tanoma wetland allows for the study of bioremediation in more neutral pH setting (pH of 5.5-7.5). In this study, we look to further understand biologic, chemical, and hydrologic controls that contribute to the efficiency of the wetland. Our research will focus on the spatial and temporal distribution of biomass through the wetland system as well as changes in water and soil chemistry. Local biofilm (Leptothrix discophora ) are an important part of the remediation process, using iron from the water as an energy source. The bacteria reduce the iron content of the water, precipitating it onto the pond bed as Terraced Iron Formations (TIF). Terraces iron formations (TIF's) are correlated with localized biofilm-archaea densities where archaea thrive in iron rich sediments. By determining bacteria densities in the wetland through gram stain analysis, we can further understand their role in terraced iron formation creation, find localized TIF's that occur, and correlate methane production due to archaea in that location. Mapping TIF locations and identifying bacteria densities will help determine the bioremediation effects on the overall efficiency of iron reduction throughout the Tanoma AMD passive remediation system.

The role of anti-inflammatory agents in age-related macular degeneration (AMD) treatment

PubMed Central

Wang, Y; Wang, V M; Chan, C-C

2011-01-01

Although age-related macular degeneration (AMD) is not a classic inflammatory disease like uveitis, inflammation has been found to have an important role in disease pathogenesis and progression. Innate immunity and autoimmune components, such as complement factors, chemokines, cytokines, macrophages, and ocular microglia, are believed to be heavily involved in AMD development. Targeting these specific inflammatory molecules has recently been explored in an attempt to better understand and treat AMD. Although antivascular endothelial growth factor therapy is the first line of defence against neovascular AMD, anti-inflammatory agents such as corticosteroids, nonsteroidal anti-inflammatory drugs (NSAIDs), immunosuppressive agents (eg, methotrexate and rapamycin), and biologics (eg, infliximab, daclizumab, and complement inhibitors) may provide an adjunct or alternative mechanism to suppress the inflammatory processes driving AMD progression. Further investigation is required to evaluate the long-term safety and efficacy of these drugs for both neovascular and non-neovascular AMD. PMID:21183941

Cellular models and therapies for age-related macular degeneration

PubMed Central

Forest, David L.; Johnson, Lincoln V.; Clegg, Dennis O.

2015-01-01

ABSTRACT Age-related macular degeneration (AMD) is a complex neurodegenerative visual disorder that causes profound physical and psychosocial effects. Visual impairment in AMD is caused by the loss of retinal pigmented epithelium (RPE) cells and the light-sensitive photoreceptor cells that they support. There is currently no effective treatment for the most common form of this disease (dry AMD). A new approach to treating AMD involves the transplantation of RPE cells derived from either human embryonic or induced pluripotent stem cells. Multiple clinical trials are being initiated using a variety of cell therapies. Although many animal models are available for AMD research, most do not recapitulate all aspects of the disease, hampering progress. However, the use of cultured RPE cells in AMD research is well established and, indeed, some of the more recently described RPE-based models show promise for investigating the molecular mechanisms of AMD and for screening drug candidates. Here, we discuss innovative cell-culture models of AMD and emerging stem-cell-based therapies for the treatment of this vision-robbing disease. PMID:26035859

The role of omega-3 and micronutrients in age-related macular degeneration.

PubMed

Querques, Giuseppe; Souied, Eric H

2014-01-01

Age-related macular degeneration (AMD) is the leading cause of irreversible vision loss in the United States, Europe, and other developed countries. Although the pathogenesis of AMD remains unclear, current evidence suggests a multifactorial aetiology. Nutrition may play an important role in the development and progression of AMD. There have been several epidemiological studies suggesting that omega-3 fatty acids could have a protective role in AMD, but a beneficial effect remains to be demonstrated in randomized controlled trials. There also exists a substantial body of evidence suggesting that protection against AMD may be provided by specific micronutrients (vitamins and minerals and antioxidants). The identification of risk factors for the development and progression of AMD is of particular importance for understanding the origins of the disorder and for establishing strategies for its prevention. We examine the relationship between dietary omega-3 intake and the incidence and progression of AMD, as well as the role of omega-3 supplementation in the prevention of the disorder, and also explore the role of other micronutrients in AMD. Copyright © 2014 Elsevier Inc. All rights reserved.

C-Reactive Protein as a Therapeutic Target in Age-Related Macular Degeneration.

PubMed

Molins, Blanca; Romero-Vázquez, Sara; Fuentes-Prior, Pablo; Adan, Alfredo; Dick, Andrew D

2018-01-01

Age-related macular degeneration (AMD), a retinal degenerative disease, is the leading cause of central vision loss among the elderly population in developed countries and an increasing global burden. The major risk is aging, compounded by other environmental factors and association with genetic variants for risk of progression. Although the etiology of AMD is not yet clearly understood, several pathogenic pathways have been proposed, including dysfunction of the retinal pigment epithelium, inflammation, and oxidative stress. The identification of AMD susceptibility genes encoding complement factors and the presence of complement and other inflammatory mediators in drusen, the hallmark deposits of AMD, support the concept that local inflammation and immune-mediated processes play a key role in AMD pathogenesis that may be accelerated through systemic immune activation. In this regard, increased levels of circulating C-reactive protein (CRP) have been associated with higher risk of AMD. Besides being a risk marker for AMD, CRP may also play a role in the progression of the disease as it has been identified in drusen, and we have recently found that its monomeric form (mCRP) induces blood retinal barrier disruption in vitro . In this review, we will address recent evidence that links CRP and AMD pathogenesis, which may open new therapeutic opportunities to prevent the progression of AMD.

AMD-stability in the presence of first-order mean motion resonances

NASA Astrophysics Data System (ADS)

Petit, A. C.; Laskar, J.; Boué, G.

2017-11-01

The angular momentum deficit (AMD)-stability criterion allows to discriminate between a priori stable planetary systems and systems for which the stability is not granted and needs further investigations. AMD-stability is based on the conservation of the AMD in the averaged system at all orders of averaging. While the AMD criterion is rigorous, the conservation of the AMD is only granted in absence of mean-motion resonances (MMR). Here we extend the AMD-stability criterion to take into account mean-motion resonances, and more specifically the overlap of first-order MMR. If the MMR islands overlap, the system will experience generalized chaos leading to instability. The Hamiltonian of two massive planets on coplanar quasi-circular orbits can be reduced to an integrable one degree of freedom problem for period ratios close to a first-order MMR. We use the reduced Hamiltonian to derive a new overlap criterion for first-order MMR. This stability criterion unifies the previous criteria proposed in the literature and admits the criteria obtained for initially circular and eccentric orbits as limit cases. We then improve the definition of AMD-stability to take into account the short term chaos generated by MMR overlap. We analyze the outcome of this improved definition of AMD-stability on selected multi-planet systems from the Extrasolar Planets Encyclopædia.

Lack of association of CFD polymorphisms with advanced age-related macular degeneration.

PubMed

Zeng, Jiexi; Chen, Yuhong; Tong, Zongzhong; Zhou, Xinrong; Zhao, Chao; Wang, Kevin; Hughes, Guy; Kasuga, Daniel; Bedell, Matthew; Lee, Clara; Ferreyra, Henry; Kozak, Igor; Haw, Weldon; Guan, Jean; Shaw, Robert; Stevenson, William; Weishaar, Paul D; Nelson, Mark H; Tang, Luosheng; Zhang, Kang

2010-11-03

Age-related macular degeneration (AMD) is the most common cause of irreversible central vision loss worldwide. Research has linked AMD susceptibility with dysregulation of the complement cascade. Typically, complement factor H (CFH), complement factor B (CFB), complement component 2 (C2), and complement component 3 (C3) are associated with AMD. In this paper, we investigated the association between complement factor D (CFD), another factor of the complement system, and advanced AMD in a Caucasian population. Six single nucleotide polymorphisms (SNPs), rs1683564, rs35186399, rs1683563, rs3826945, rs34337649, and rs1651896, across the region covering CFD, were chosen for this study. One hundred and seventy-eight patients with advanced AMD and 161 age-matched normal controls were genotyped. Potential positive signals were further tested in another independent 445 advanced AMD patients and 190 controls. χ2 tests were performed to compare the allele frequencies between case and control groups. None of the six SNPs of CFD was found to be significantly associated with advanced AMD in our study. Our findings suggest that CFD may not play a major role in the genetic susceptibility to AMD because no association was found between the six SNPs analyzed in the CFD region and advanced AMD.

Do nutritional supplements have a role in age macular degeneration prevention?

PubMed

Pinazo-Durán, Maria D; Gómez-Ulla, Francisco; Arias, Luis; Araiz, Javier; Casaroli-Marano, Ricardo; Gallego-Pinazo, Roberto; García-Medina, Jose J; López-Gálvez, Maria Isabel; Manzanas, Lucía; Salas, Anna; Zapata, Miguel; Diaz-Llopis, Manuel; García-Layana, Alfredo

2014-01-01

Purpose. To review the proposed pathogenic mechanisms of age macular degeneration (AMD), as well as the role of antioxidants (AOX) and omega-3 fatty acids ( ω -3) supplements in AMD prevention. Materials and Methods. Current knowledge on the cellular/molecular mechanisms of AMD and the epidemiologic/experimental studies on the effects of AOX and ω -3 were addressed all together with the scientific evidence and the personal opinion of professionals involved in the Retina Group of the OFTARED (Spain). Results. High dietary intakes of ω -3 and macular pigments lutein/zeaxanthin are associated with lower risk of prevalence and incidence in AMD. The Age-Related Eye Disease study (AREDS) showed a beneficial effect of high doses of vitamins C, E, beta-carotene, and zinc/copper in reducing the rate of progression to advanced AMD in patients with intermediate AMD or with one-sided late AMD. The AREDS-2 study has shown that lutein and zeaxanthin may substitute beta-carotene because of its potential relationship with increased lung cancer incidence. Conclusion. Research has proved that elder people with poor diets, especially with low AOX and ω -3 micronutrients intake and subsequently having low plasmatic levels, are more prone to developing AMD. Micronutrient supplementation enhances antioxidant defense and healthy eyes and might prevent/retard/modify AMD.

Bmp6 Regulates Retinal Iron Homeostasis and Has Altered Expression in Age-Related Macular Degeneration

PubMed Central

Hadziahmetovic, Majda; Song, Ying; Wolkow, Natalie; Iacovelli, Jared; Kautz, Leon; Roth, Marie-Paule; Dunaief, Joshua L.

2011-01-01

Iron-induced oxidative stress causes hereditary macular degeneration in patients with aceruloplasminemia. Similarly, retinal iron accumulation in age-related macular degeneration (AMD) may exacerbate the disease. The cause of retinal iron accumulation in AMD is poorly understood. Given that bone morphogenetic protein 6 (Bmp6) is a major regulator of systemic iron, we examined the role of Bmp6 in retinal iron regulation and in AMD pathogenesis. Bmp6 was detected in the retinal pigment epithelium (RPE), a major site of pathology in AMD. In cultured RPE cells, Bmp6 was down-regulated by oxidative stress and up-regulated by iron. Intraocular Bmp6 protein injection in mice up-regulated retinal hepcidin, an iron regulatory hormone, and altered retinal labile iron levels. Bmp6−/− mice had age-dependent retinal iron accumulation and degeneration. Postmortem RPE from patients with early AMD exhibited decreased Bmp6 levels. Because oxidative stress is associated with AMD pathogenesis and down-regulates Bmp6 in cultured RPE cells, the diminished Bmp6 levels observed in RPE cells in early AMD may contribute to iron build-up in AMD. This may in turn propagate a vicious cycle of oxidative stress and iron accumulation, exacerbating AMD and other diseases with hereditary or acquired iron excess. PMID:21703414

Passive aerobic treatment of net-alkaline, iron-laden drainage from a flooded underground anthracite mine, Pennsylvania, USA

USGS Publications Warehouse

Cravotta, C.A.

2007-01-01

This report evaluates the results of a continuous 4.5-day laboratory aeration experiment and the first year of passive, aerobic treatment of abandoned mine drainage (AMD) from a typical flooded underground anthracite mine in eastern Pennsylvania, USA. During 1991-2006, the AMD source, locally known as the Otto Discharge, had flows from 20 to 270 L/s (median 92 L/s) and water quality that was consistently suboxic (median 0.9 mg/L O2) and circumneutral (pH ??? 6.0; net alkalinity >10) with moderate concentrations of dissolved iron and manganese and low concentrations of dissolved aluminum (medians of 11, 2.2, and <0.2 mg/L, respectively). In 2001, the laboratory aeration experiment demonstrated rapid oxidation of ferrous iron (Fe 2+) without supplemental alkalinity; the initial Fe2+ concentration of 16.4 mg/L decreased to less than 0.5 mg/L within 24 h; pH values increased rapidly from 5.8 to 7.2, ultimately attaining a steady-state value of 7.5. The increased pH coincided with a rapid decrease in the partial pressure of carbon dioxide (PCO2) from an initial value of 10 -1.1atm to a steady-state value of 10-3.1atm. From these results, a staged aerobic treatment system was conceptualized consisting of a 2 m deep pond with innovative aeration and recirculation to promote rapid oxidation of Fe2+, two 0.3 m deep wetlands to facilitate iron solids removal, and a supplemental oxic limestone drain for dissolved manganese and trace-metal removal. The system was constructed, but without the aeration mechanism, and began operation in June 2005. During the first 12 months of operation, estimated detention times in the treatment system ranged from 9 to 38 h. However, in contrast with 80-100% removal of Fe2+ over similar elapsed times during the laboratory aeration experiment, the treatment system typically removed less than 35% of the influent Fe2+. Although concentrations of dissolved CO2 decreased progressively within the treatment system, the PCO2 values for treated effluent remained elevated (10-2.4 to 10-1.7atm). The elevated PCO 2 maintained the pH within the system at values less than 7 and hence slowed the rate of Fe2+ oxidation compared to the aeration experiment. Kinetic models of Fe2+ oxidation that consider effects of pH and dissolved O2 were incorporated in the geochemical computer program PHREEQC to evaluate the effects of detention time, pH, and other variables on Fe2+ oxidation and removal rates. These models and the laboratory aeration experiment indicate that performance of this and other aerobic wetlands for treatment of net-alkaline AMD could be improved by aggressive, continuous aeration in the initial stage to decrease PCO 2, increase pH, and accelerate Fe2+ oxidation. ?? 2007 Springer-Verlag.

Education, socio-economic status and age-related macular degeneration in Asians: the Singapore Malay Eye Study.

PubMed

Cackett, P; Tay, W T; Aung, T; Wang, J J; Shankar, A; Saw, S M; Mitchell, P; Wong, T Y

2008-10-01

Low socio-economic status is increasingly being identified as a risk marker for chronic diseases, but few studies have investigated the link between socio-economic factors and age-related macular degeneration (AMD). The present study aimed to assess the association between socio-economic status and the prevalence of AMD. A population-based cross-sectional study of 3280 (78.7% response rate) Malay adults aged 40-80 years residing in 15 south-western districts of Singapore. AMD was graded from retinal photographs at a central reading centre using the modified Wisconsin AMD scale. Early and late AMD signs were graded from retinal photographs following the Wisconsin grading system. Socio-economic status including education, housing type and income were determined from a detailed interview. Of the participants, 3265 had photographs of sufficient quality for grading of AMD. Early AMD was present in 168 (5.1%) and late AMD in 21 (0.6%). After adjusting for age, gender, smoking, hypertension, diabetes and body mass index, participants with lower educational levels were significantly more likely to have early AMD (multivariate OR 2.2, 95% CI 1.2 to 4.0). This association was stronger in persons who had never smoked (multivariate OR 3.6, 95% confidence CI 1.4 to 9.4). However, no association with housing type or income was seen. Low educational level is associated with a higher prevalence of early AMD signs in our Asian population, independent of age, cardiovascular risk factors and cigarette smoking.

Healthy Lifestyles Related to Subsequent Prevalence of Age-Related Macular Degeneration

PubMed Central

Mares, JA; Voland, R.; Sondel, SA; Millen, A.E.; LaRowe, T; Moeller, SM; Klein, M.L.; Blodi, B.A; Chappell, R.; Tinker, L.; Ritenbaugh, C; Gehrs, K; Sarto, G; Johnson, E.J; Snodderly, M; Wallace, RB

2010-01-01

Purpose The relationships between lifestyle behaviors of diet, smoking and physical activity and the subsequent prevalence of age-related macular degeneration (AMD) were investigated. Methods The population included 1,313 participants (55 to 74 years) in the Carotenoids in Age-Related Eye Disease Study (CAREDS), an ancillary study of the Women's Health Initiative Observational Study (WHIOS). Scores on a modified 2005 Healthy Eating Index (mHEI) were assigned using responses to a food frequency questionnaire administered at WHIOS baseline (1994-1998). Physical activity and lifetime smoking history were queried. An average of six years later, stereoscopic fundus photographs were taken to assess presence and severity of AMD; present in 202 women, 94% of whom had early AMD, the primary outcome. Results In multivariate models, women whose diets scored in the highest compared with the lowest quintile on the mHEI had a 46% lower odds for early AMD. Women in the highest vs. lowest quintile for physical activity (MET- Hrs/Wk) had 54% lower odds for early AMD. Although smoking, alone was not independently associated with AMD, having a combination of three healthy lifestyles (healthy diet, physical activity and not smoking) was associated with a 71% lower odds for AMD compared with having high risk scores (P=0.0004). Conclusions Modifying lifestyles might reduce risk for early AMD as much as 3-fold, lowering the risk for advanced AMD in a person's lifetime and the social and economic costs of AMD to society. PMID:21149749

Prevalence of age-related macular degeneration in rural southern China: the Yangxi Eye Study.

PubMed

Jin, Guangming; Ding, Xiaohu; Xiao, Wei; Xu, Xiao; Wang, Lanhua; Han, Xiaotong; Xiao, Ou; Liu, Ran; Wang, Wei; Yan, William; An, Lei; Zhao, Jialiang; He, Mingguang

2018-05-01

To describe the prevalence of age-related macular degeneration (AMD) among older adults in rural southern mainland China. Eligible persons aged 50 years or over were identified by geographically defined cluster sampling from Yangxi County, Guangdong Province, China. Participants underwent a standardised interview and comprehensive eye examinations from August to November in 2014. Digital retinal photographs were graded for AMD lesions using the Clinical Classification of Age-Related Macular Degeneration developed by the Beckman Initiative for Macular Research Classification Committee. Age-standardised prevalence of AMD and AMD lesions was calculated using the 2010 world population data and compared with those of other populations. Of 5825 subjects who participated (90.7% response rate), 4881 (83.8%) had fundus photographs gradable for AMD. Early, intermediate and late AMD were present in 2003 (41.0%), 879 (18.0%) and 42 (0.86%) participants. The age-standardised prevalence of early, intermediate and late AMD was 40.4% (95% CI 39.6% to 41.2%), 17.6% (95% CI 17.0% to 18.2%) and 0.79% (95% CI 0.65% to 0.95%), respectively. Total AMD was more prevalent in men than in women (62.8% vs 57.1%). AMD is an important public health concern for rural southern China, and the prevalence of AMD was higher in men than in women. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Retinal vascular caliber, iris color, and age-related macular degeneration in the Irish Nun Eye Study.

PubMed

McGowan, Amy; Silvestri, Giuliana; Moore, Evelyn; Silvestri, Vittorio; Patterson, Christopher C; Maxwell, Alexander P; McKay, Gareth J

2014-12-18

To evaluate the relationship between retinal vascular caliber (RVC), iris color, and age-related macular degeneration (AMD) in elderly Irish nuns. Data from 1233 participants in the cross-sectional observational Irish Nun Eye Study were assessed from digital photographs with a standardized protocol using computer-assisted software. Macular images were graded according to the modified Wisconsin Age-related Maculopathy Grading System. Regression models were used to assess associations, adjusting for age, mean arterial blood pressure, body mass index, refraction, and fellow RVC. In total, 1122 (91%) participants had gradable retinal images of sufficient quality for vessel assessment (mean age: 76.3 years [range, 56-100 years]). In an unadjusted analysis, we found some support for a previous finding that individuals with blue iris color had narrower retinal venules compared to those with brown iris color (P < 0.05), but this was no longer significant after adjustment. Age-related macular degeneration status was categorized as no AMD, any AMD, and late AMD only. Individuals with any AMD (early or late AMD) had significantly narrower arterioles and venules compared to those with no AMD in an unadjusted analysis, but this was no longer significant after adjustment. A nonsignificant reduced risk of any AMD or late AMD only was observed in association with brown compared to blue iris color, in both unadjusted and adjusted analyses. Retinal vascular caliber was not significantly associated with iris color or early/late AMD after adjustment for confounders. A lower but nonsignificant AMD risk was observed in those with brown compared to blue iris color. Copyright 2015 The Association for Research in Vision and Ophthalmology, Inc.

A 5-year multicenter prospective cohort study on the long-term visual prognosis and predictive factors for visual outcome in Japanese patients with age-related macular degeneration: the AMD2000 study.

PubMed

Akagi-Kurashige, Yumiko; Tsujikawa, Akitaka; Yuzawa, Mitsuko; Ishibashi, Tatsuro; Nakanishi, Hideo; Nakatani, Eiji; Teramukai, Satoshi; Fukushima, Masanori; Yoshimura, Nagahisa

2018-03-01

In this study (AMD2000), we aimed to determine the visual prognosis of Japanese patients with age-related macular degeneration (AMD). This was a multicenter prospective observational cohort study. In total, 460 patients with AMD were recruited from April 2006 to March 2009 from 18 clinical trial sites in Japan. They were followed up for 5 years, as they continued to receive medical treatment. Of the 409 study eyes followed up for at least 1 year, 243 eyes (59.4%) were treated with photodynamic therapy (PDT) using verteporfin, and 58 eyes (14.2%) were treated with intravitreal injections of antivascular endothelial growth factor agents as the initial treatment. The mean best-corrected visual acuities (BCVA) for typical AMD (tAMD; 0.688 ± 0.498) and polypoidal choroidal vasculopathy (PCV; 0.451 ± 0.395) were significantly less at 2 years (tAMD, 0.779 ± 0.632, P < 0.05; PCV, 0.534 ± 0.618, P < 0.05) and at 5 years (AMD, 0.873 ± 0.718, P < 0.05; PCV, 0.635 ± 0.668, P < 0.05) than at baseline. In eyes with tAMD, absence of blocked fluorescence was associated with 5-year maintenance of the baseline BCVA. Regarding PCV, the presence of polypoidal lesions and cystoid macular edema as well as the lesion size was associated with 5-year maintenance of the baseline BCVA. In some patients, the diagnosis changed: of the 192 eyes initially diagnosed with typical AMD, 19 were newly diagnosed with PCV during follow-up. Maintaining the baseline BCVA over the long term is difficult in Japanese eyes with wet AMD.

Nutritional Modulation of Age-Related Macular Degeneration

PubMed Central

Weikel, Karen A; Taylor, Allen

2012-01-01

Age-related macular degeneration (AMD) is the leading cause of blindness in the elderly worldwide. It affects 30–50 million individuals and clinical hallmarks of AMD are observed in at least one third of persons over the age of 75 in industrialized countries (Gehrs et al., 2006). Costs associated with AMD are in excess of $340 billion US (American-Health-Assistance-Foundation, 2012). The majority of AMD patients in the United States are not eligible for clinical treatments (Biarnes et al., 2011; Klein et al., 2011). Preventive interventions through dietary modulation are attractive strategies because many studies suggest a benefit of micro and macronutrients with respect to AMD, as well as other age-related debilities, and with few, if any, adverse effects (Chiu, 2011). Preservation of vision would enhance quality of life for millions of elderly people, and alleviate the personal and public health financial burden of AMD (Frick et al., 2007; Wood et al., 2011). Observational studies indicate that maintaining adequate levels of omega-3 fatty acids (i.e. with 2 servings/wk of fish) or a low glycemic index diet may be particularly beneficial for early AMD and that higher levels of carotenoids may be protective, most probably, against neovascular AMD. Intervention trials are needed to better understand the full effect of these nutrients and/or combinations of nutrients on retinal health. Analyses that describe effects of a nutrient on onset and/or progress of AMD are valuable because they indicate the value of a nutrient to arrest AMD at the early stages. This comprehensive summary provides essential information about the value of nutrients with regard to diminishing risk for onset or progress of AMD and can serve as a guide until data from ongoing intervention trials are available. PMID:22503690

Cost-effectiveness of anti-oxidant vitamins plus zinc treatment to prevent the progression of intermediate age-related macular degeneration. A Singapore perspective.

PubMed

Saxena, Nakul; George, Pradeep Paul; Heng, Bee Hoon; Lim, Tock Han; Yong, Shao Onn

2015-06-01

To determine if providing high dose anti-oxidant vitamins and zinc treatment age-related eye disease study (AREDS formulation) to patients with intermediate age-related macular degeneration (AMD) aged 40-79 years from Singapore is cost-effective in preventing progression to wet AMD. A hypothetical cohort of category 3 and 4 AMD patients from Singapore was followed for 5 calendar years to determine the number of patients who would progress to wet AMD given the following treatment scenarios: (a) AREDS formulation or placebo followed by ranibizumab (as needed) for wet AMD. (b) AREDS formulation or placebo followed by bevacizumab (monthly) for wet AMD. (c) AREDS formulation or placebo followed by aflibercept (VIEW I and II trial treatment regimen). Costs were estimated for the above scenarios from the providers' perspective, and cost-effectiveness was measured by cost per disability-adjusted life year (DALY) averted with a disability weight of 0.22 for wet AMD. The costs were discounted at an annual rate of 3%. Over 5400 patients could be prevented from progressing to wet AMD cumulatively if AREDS formulation were prescribed. AREDS formulation followed by ranibizumab was cost-effective compared to placebo-ranibizumab or placebo-aflibercept combinations (cost per DALY averted: SGD$23,662.3 and SGD$21,138.8, respectively). However, bevacizumab (monthly injections) alone was more cost-effective compared to AREDS formulation followed by bevacizumab. Prophylactic treatment with AREDS formulation for intermediate AMD patients followed by ranibizumab or for patients who progressed to wet AMD was found to be cost-effective. These findings have implications for intermediate AMD screening, treatment and healthcare planning in Singapore.

Prevention and treatment of age-related macular degeneration: an update for pharmacists.

PubMed

Marshall, Leisa L; Roach, J Michael

2013-11-01

Review the current recommendations for the prevention and treatment of age-related macular degeneration (AMD). Articles indexed in PubMed (National Library of Medicine), the Cochrane Reviews and Trials, Dynamed, and Iowa Drug Information Service (IDIS) in the last 10 years using the key words macular degeneration, agerelated macular degeneration (AMD), AMD and treatment, AMD and prevention. Sixty-nine published papers were reviewed, and criteria supporting the primary objective were used to identify useful resources. The literature included practice guidelines, original research articles, review articles, product prescribing information, and supplement product information for the prevention and treatment of AMD. AMD is a leading cause of visual impairment in older adults. At present there is no cure for advanced AMD, but intravitreal vascular endothelial growth factor inhibitors minimize and even reverse vision loss in patients with AMD of the neovascular type. In the Age-Related Eye Disease Study (AREDS), participants with intermediate AMD who received a supplement combination of vitamins C and E, beta-carotene, and zinc had a greater delay in progression to advanced AMD than those participants who received a portion of these supplements. In the second AREDS, AREDS2, the addition of lutein + zeaxanthin, docosahexaenoic acid (DHA) + eicosapentaenoic acid (EPA), or lutein + zeaxanthin and DHA + EPA to the complete AREDS formulation did not further reduce the risk of progression to advanced AMD. Subgroup analyses indicated that additional research with lutein + zeaxanthin supplementation is warranted as it was beneficial in participants with low dietary intake of lutein + zeaxanthin. A formulation without beta-carotene may be best for most patients, especially smokers or former smokers. Health care professionals will want to consider patient-specific information before recommending ocular health supplements.

Preferential Hyperacuity Perimeter (PreView PHP) for detecting choroidal neovascularization study.

PubMed

Alster, Yair; Bressler, Neil M; Bressler, Susan B; Brimacombe, Judith A; Crompton, R Michael; Duh, Yi-Jing; Gabel, Veit-Peter; Heier, Jeffrey S; Ip, Michael S; Loewenstein, Anat; Packo, Kirk H; Stur, Michael; Toaff, Techiya

2005-10-01

To assess the ability of the Preferential Hyperacuity Perimeter (PreView PHP; Carl Zeiss Meditec, Dublin, CA) to detect recent-onset choroidal neovascularization (CNV) resulting from age-related macular degeneration (AMD) and to differentiate it from an intermediate stage of AMD. Prospective, comparative, concurrent, nonrandomized, multicenter study. Eligible participants' study eyes had a corrected visual acuity of 20/160 or better and either untreated CNV from AMD diagnosed within the last 60 days or an intermediate stage of AMD. After obtaining consent, visual acuity with habitual correction, masked PHP testing, stereoscopic color fundus photography, and fluorescein angiography were performed. Photographs and angiograms were evaluated by graders masked to diagnosis and PHP results. The reading center's diagnosis determined if the patient was categorized as having intermediate AMD or neovascular AMD. A successful study outcome was defined a priori as a sensitivity of at least 80% and a specificity of at least 80%. Of 185 patients who gave consent to be enrolled, 11 (6%) had PHP results judged to be unreliable. An additional 52 were not included because they did not meet all eligibility criteria. Of the remaining 122 patients, 57 had an intermediate stage of AMD and 65 had neovascular AMD. The sensitivity to detect newly diagnosed CNV using PHP testing was 82% (95% confidence interval [CI], 70%-90%). The specificity to differentiate newly diagnosed CNV from the intermediate stage of AMD using PHP testing was 88% (95% CI, 76%-95%). Preferential Hyperacuity Perimeter testing can detect recent-onset CNV resulting from AMD and can differentiate it from an intermediate stage of AMD with high sensitivity and specificity. These data suggest that monitoring with PHP should detect most cases of CNV of recent onset with few false-positive results at a stage when treatment usually would be beneficial. Thus, this monitoring should be considered in the management of the intermediate stage of AMD.

C-Reactive Protein and the Incidence of Macular Degeneration – Pooled Analysis of 5 Cohorts

PubMed Central

Mitta, Vinod P.; Christen, William G.; Glynn, Robert J.; Semba, Richard D.; Ridker, Paul M.; Rimm, Eric B.; Hankinson, Susan E.; Schaumberg, Debra A.

2013-01-01

Objectives To investigate the relationship between high-sensitivity C-reactive protein (hsCRP) and future risk of age-related macular degeneration (AMD) in US men and women. Methods We measured hsCRP in baseline blood samples from participants in five ongoing cohort studies. Patients were initially free of AMD. We prospectively identified 647 incident cases of AMD and selected age- and sex-matched controls for each AMD case (2 controls for each case with dry AMD, or 3 controls for each case of neovascular AMD). We used conditional logistic regression models to examine the relationship between hsCRP and AMD, and pooled findings using meta-analytic techniques. Results After adjusting for cigarette smoking status, participants with high (> 3 mg/L) compared with low (< 1 mg/L) hsCRP levels, had cohort-specific odds ratios (OR) for incident AMD ranging from 0.94 (95% CI 0.58-1.51) in the Physicians’ Health Study to 2.59 (95% CI 0.58-11.67) in the Women’s Antioxidant and Folic Acid Cardiovascular Study. After testing for heterogeneity between studies (Q=5.61, p=0.23), we pooled findings across cohorts, and observed a significantly increased risk of incident AMD for high versus low hsCRP levels (OR=1.49, 95% CI 1.06-2.08). Risk of neovascular AMD was also increased among those with high hsCRP levels (OR=1.84, 95% CI 1.14-2.98). Conclusion Overall these pooled findings from 5 prospective cohorts add further evidence that elevated levels of hsCRP predict greater future risk of AMD. This information might shed light on underlying mechanisms, and could be of clinical utility in the identification of persons at high risk of AMD who may benefit from increased adherence to lifestyle recommendations, eye examination schedules, and therapeutic protocols. PMID:23392454

The effect of non-neovascular age-related macular degeneration on face recognition performance.

PubMed

Taylor, Deanna J; Smith, Nicholas D; Binns, Alison M; Crabb, David P

2018-04-01

There is a well-established research base surrounding face recognition in patients with age-related macular degeneration (AMD). However, much of this existing research does not differentiate between results obtained for 'wet' AMD and 'dry' AMD. Here, we test the hypothesis that face recognition performance is worse in patients with dry AMD compared with visually healthy peers. Patients (>60 years of age, logMAR binocular visual acuity 0.7 or better) with dry AMD of varying severity and visually healthy age-related peers (controls) completed a modified version of the Cambridge Face Memory Test (CFMT). Percentage of correctly identified faces was used as an outcome measure for performance for each participant. A 90% normative reference limit was generated from the distribution of CFMT scores recorded in the visually healthy controls. Scores for AMD participants were then specifically compared to this limit, and comparisons between average scores in the AMD severity groups were investigated. Thirty patients (median [interquartile range] age of 76 [70, 79] years) and 34 controls (median age of 70 [64, 75] years) were examined. Four, seventeen and nine patients were classified as having early, intermediate and late AMD (geographic atrophy) respectively. Five (17%) patients recorded a face recognition performance worse than the 90% limit (Fisher's exact test, p = 0.46) set by controls; four of these had geographic atrophy. Patients with geographic atrophy identified fewer faces on average (±SD) (61% ± 22%) than those with early and intermediate AMD (75 ± 11%) and controls (74% ± 11%). People with dry AMD may not suffer from problems with face recognition until the disease is in its later stages; those with late AMD (geographic atrophy) are likely to have difficulty recognising faces. The results from this study should influence the management and expectations of patients with dry AMD in both community practice and hospital clinics.

Fate of Acrylamide in Soil and Groundwater Systems: Microbial Degradation

NASA Astrophysics Data System (ADS)

Labahn, S.; Moser, D.; Arrowood, T.; Young, M.; Robleto, E.

2007-12-01

Acrylamide monomer (AMD), a suspected human neurotoxin and carcinogen, is present as a contaminant (up to 0.05%) in commercial preparations of polyacrylamide (PAM). PAM is currently being evaluated for wide-spread use as a temporary water-delivery canal sealant across the western United States. To better constrain potential risks associated with PAM applications, we examined the capacity of natural canal microorganisms to degrade AMD in laboratory and field experiments. Dilution cultivation and enrichment approaches were employed to determine the abundance of culturable microorganisms in several canal habitats which can utilize AMD as a sole nitrogen source (typically 104-106/mL) and a collection of isolates was developed. AMD-degrading microorganisms in our collection fell within a limited diversity of genera including Arthrobacter, Xanthomonas, and Pseudomonas; with the latter demonstrating highest capacity for degrading AMD under laboratory conditions. One strain of Pseudomonas fluorescens, isolated from Klamath Irrigation District (Klamath Falls, OR) canal sediment, was chosen for further study in part because this species is well-studied and ubiquitous. The potential for microbial AMD degradation was tested under laboratory conditions using this strain in repacked short (15 cm) column tests with two relevant soil types (sand and loam). Subsequently, the capacity of mixed natural microbial populations to degrade AMD was examined using soil cores collected from the Highline Canal (Rocky Ford, CO), and canal water/sediment slurries with spiked (5 ppm AMD) in situ bottle tests. Degradation of the monomer in the repacked column experiments was evaluated using a step input of 5 ppm AMD and the canal columns were tested with a range of AMD concentrations (1-5 ppm) followed by quantification with an HPLC. The repacked soil columns inoculated with P. fluorescens demonstrated 80-100% AMD degradation within 12 hours. Natural microbial communities in fresh canal sediment columns produced varying levels of AMD degradation, ranging from 40-50% after 36 hours. The in situ bottle test resulted in 50% degradation after 72 hours. Experimental AMD degradation rates and transport parameters, such as sorption and retardation, were combined to model AMD transport in canal and ground water systems (Arrowood et al. 2007). Initial calculations demonstrate the importance of the microbial role in removal of the monomer and infer possible implications informing the development of safe and effective PAM application protocols.

Prediction model for prevalence and incidence of advanced age-related macular degeneration based on genetic, demographic, and environmental variables.

PubMed

Seddon, Johanna M; Reynolds, Robyn; Maller, Julian; Fagerness, Jesen A; Daly, Mark J; Rosner, Bernard

2009-05-01

The joint effects of genetic, ocular, and environmental variables were evaluated and predictive models for prevalence and incidence of AMD were assessed. Participants in the multicenter Age-Related Eye Disease Study (AREDS) were included in a prospective evaluation of 1446 individuals, of which 279 progressed to advanced AMD (geographic atrophy or neovascular disease) and 1167 did not progress during 6.3 years of follow-up. For prevalent AMD, 509 advanced cases were compared with 222 controls. Covariates for the incidence analysis included age, sex, education, smoking, body mass index (BMI), baseline AMD grade, and the AREDS vitamin-mineral treatment assignment. DNA specimens were evaluated for six variants in five genes related to AMD. Unconditional logistic regression analyses were performed for prevalent and incident advanced AMD. An algorithm was developed and receiver operating characteristic curves and C statistics were calculated to assess the predictive ability of risk scores to discriminate progressors from nonprogressors. All genetic polymorphisms were independently related to prevalence of advanced AMD, controlling for genetic factors, smoking, BMI, and AREDS treatment. Multivariate odds ratios (ORs) were 3.5 (95% confidence interval [CI], 1.7-7.1) for CFH Y402H; 3.7 (95% CI, 1.6-8.4) for CFH rs1410996; 25.4 (95% CI, 8.6-75.1) for LOC387715 A69S (ARMS2); 0.3 (95% CI, 0.1-0.7) for C2 E318D; 0.3 (95% CI, 0.1-0.5) for CFB; and 3.6 (95% CI, 1.4-9.4) for C3 R102G, comparing the homozygous risk/protective genotypes to the referent genotypes. For incident AMD, all these variants except CFB were significantly related to progression to advanced AMD, after controlling for baseline AMD grade and other factors, with ORs from 1.8 to 4.0 for presence of two risk alleles and 0.4 for the protective allele. An interaction was seen between CFH402H and treatment, after controlling for all genotypes. Smoking was independently related to AMD, with a multiplicative joint effect with genotype on AMD risk. The C statistic for the full model with all variables was 0.831 for progression to advanced AMD. Factors reflective of nature and nurture are independently related to prevalence and incidence of advanced AMD, with excellent predictive power.

Association of Anticholinergic Drug Use With Risk for Late Age-Related Macular Degeneration.

PubMed

Aldebert, Gauthier; Faillie, Jean-Luc; Hillaire-Buys, Dominique; Mura, Thibault; Carrière, Isabelle; Delcourt, Cécile; Creuzot-Garcher, Catherine; Villain, Max; Daien, Vincent

2018-05-24

Amyloid-β is a major component of retinal drusen, the primary lesions of age-related macular degeneration (AMD), and autopsy and animal models suggested that anticholinergic drug (ACD) use increased brain amyloid-β deposition. To investigate the association between exposure to ACDs and late AMD (features of neovascular AMD or geographic atrophy of the retinal pigment epithelium in at least 1 eye). A multicenter case-control study in 4 French ophthalmologic centers comprising 200 cases with late AMD and 200 controls enrolled from July 2016 to June 2017. Exposure to at least 3 months of ACDs started before AMD diagnosis was recorded during a specific interview. A dose-effect association with cumulative exposure duration and Anticholinergic Burden Score was explored. The association between ACD exposure and AMD was assessed by multivariate logistic regression analysis adjusted for age, sex, smoking status, family history of AMD, alcohol consumption, and use of anticoagulant and anti-inflammatory drugs. Odds ratios (ORs) and 95% confidence intervals were estimated. Association between exposure to ACDs and late AMD. Among case participants, the mean (SD) age was 74.8 (9.2) years, 129 (64.5%) were women, 192 (96%) were white, 65 (32.5%) had geographic atrophy, 135 (67.5%) had neovascular AMD, 116 (58%) had unilateral AMD, and 84 (42%) had bilateral AMD. Among control participants, the mean (SD) age was 75.5 (7.2) years, with 116 (58%) women and 187 (93.5%) white participants. Twenty-six cases (13%) and 10 controls (5%) were exposed to ACDs throughout life for at least 3 months before AMD onset. Risk of AMD was increased with ever exposure to ACDs (adjusted OR [aOR], 2.84; 95% CI, 1.33-6.06; P = .007), high Anticholinergic Burden Score (≥3) (aOR, 6.42; 95% CI, 1.38-29.92; P = .02), and longest cumulative exposure to ACD (≥15 years) (aOR, 5.88; 95% CI, 1.22-28.31; P = .03). Risk of late AMD may be increased with at least 3 months' use of ACDs. A dose-effect association was suggested by a greater association with prolonged use and high Anticholinergic Burden Score. Further studies, in particular those with longitudinal design, are needed to confirm this association.

Joint Associations of Diet, Lifestyle, and Genes with Age-Related Macular Degeneration.

PubMed

Meyers, Kristin J; Liu, Zhe; Millen, Amy E; Iyengar, Sudha K; Blodi, Barbara A; Johnson, Elizabeth; Snodderly, D Max; Klein, Michael L; Gehrs, Karen M; Tinker, Lesley; Sarto, Gloria E; Robinson, Jennifer; Wallace, Robert B; Mares, Julie A

2015-11-01

Unhealthy lifestyles have been associated with increased odds for age-related macular degeneration (AMD). Whether this association is modified by genetic risk for AMD is unknown and was investigated. Interactions between healthy lifestyles AMD risk genotypes were studied in relation to the prevalence of AMD, assessed 6 years later. Women 50 to 79 years of age in the Carotenoids in Age-Related Eye Disease Study with exposure and AMD data (n=1663). Healthy lifestyle scores (0-6 points) were assigned based on Healthy Eating Index scores, physical activity (metabolic equivalent of task hours/week), and smoking pack years assessed in 1994 and 1998. Genetic risk was based on Y402H in complement factor H (CFH) and A69S in age-related maculopathy susceptibility locus 2 (ARMS2). Additive and multiplicative interactions in odds ratios were assessed using the synergy index and a multiplicative interaction term, respectively. AMD presence and severity were assessed from grading of stereoscopic fundus photographs taken in 2001-2004. AMD was present in 337 women, 91% of whom had early AMD. The odds of AMD were 3.3 times greater (95% confidence interval [CI], 1.8-6.1) in women with both low healthy lifestyle score (0-2) and high-risk CFH genotype (CC), relative to those who had low genetic risk (TT) and high healthy lifestyle scores (4-6). There were no significant additive (synergy index [SI], 1.08; 95% CI, 0.70-1.67) or multiplicative (Pinteraction=0.94) interactions in the full sample. However, when limiting the sample to women with stable diets before AMD assessment (n=728) the odds for AMD associated with low healthy lifestyle scores and high-risk CFH genotype were strengthened (odds ratio, 4.6; 95% CI, 1.8-11.6) and the synergy index was significant (SI, 1.34; 95% CI, 1.05-1.70). Adjusting for dietary lutein and zeaxanthin attenuated, and therefore partially explained, the joint association. There were no significant additive or multiplicative interactions for ARMS2 and lifestyle score. Having unhealthy lifestyles and 2 CFH risk alleles increased AMD risk (primarily in the early stages), in an or additive or greater (synergistic) manner. However, unhealthy lifestyles increased AMD risk regardless of AMD risk genotype. Copyright © 2015 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Environmental and socioeconomic assessment of impacts by mining activities-a case study in the Certej River catchment, Western Carpathians, Romania.

PubMed

Zobrist, Jürg; Sima, Mihaela; Dogaru, Diana; Senila, Marin; Yang, Hong; Popescu, Claudia; Roman, Cecilia; Bela, Abraham; Frei, Linda; Dold, Bernhard; Balteanu, Dan

2009-08-01

In the region of the Apuseni Mountains, part of the Western Carpathians in Romania, metal mining activities have a long-standing tradition. These mining industries created a clearly beneficial economic development in the region. But their activities also caused impairments to the environment, such as acid mine drainage (AMD) resulting in long-lasting heavy metal pollution of waters and sediments. The study, established in the context of the ESTROM programme, investigated the impact of metal mining activities both from environmental and socioeconomic perspectives and tried to incorporate the results of the two approaches into an integrated proposition for mitigation of mining-related issues. The small Certej catchment, situated in the Southern Apuseni Mountains, covers an area of 78 km(2). About 4,500 inhabitants are living in the basin, in which metal mining was the main economic sector. An open pit and several abandoned underground mines are producing heavy metal-loaded acidic water that is discharged untreated into the main river. The solid wastes of mineral processing plants were deposited in several dumps and tailings impoundment embodying the acidic water-producing mineral pyrite. The natural science team collected samples from surface waters, drinking water from dug wells and from groundwater. Filtered and total heavy metals, both after enrichment, and major cations were analysed by inductively coupled plasma optical emission spectroscopy (ICP-OES). Major anions in waters, measured by ion chromatography, alkalinity and acidity were determined by titration. Solid samples were taken from river sediments and from the largest tailings dam. The latter were characterised by X-ray fluorescence and X-ray diffraction. Heavy metals in sediments were analysed after digestion. Simultaneously, the socioeconomic team performed a household survey to evaluate the perception of people related to the river and drinking water pollution by way of a logistic regression analysis. The inputs of acid mine waters drastically increased filtered heavy metal concentrations in the Certej River, e.g. Zn up to 130 mg L(-1), Fe 100 mg L(-1), Cu 2.9 mg L(-1), Cd 1.4 mg L(-1) as well as those of SO(4) up to 2.2 g L(-1). In addition, river water became acidic with pH values of pH 3. Concentrations of pollutant decreased slightly downstream due to dilution by waters from tributaries. Metal concentrations measured at headwater stations reflect background values. They fell in the range of the environmental quality standards proposed in the EU Water Framework Directive for dissolved heavy metals. The outflow of the large tailing impoundment and the groundwater downstream from two tailings dams exhibited the first sign of AMD, but they still had alkalinity. Most dug wells analysed delivered a drinking water that exhibited no sign of AMD pollution, although these wells were a distance of 7 to 25 m from the contaminated river. It seems that the Certej River does not infiltrate significantly into the groundwater. Pyrite was identified as the main sulphide mineral in the tailings dam that produces acidity and with calcite representing the AMD-neutralising mineral. The acid-base accounting proved that the potential acid-neutralising capacity in the solid phases would not be sufficient to prevent the production of acidic water in the future. Therefore, the open pits and mine waste deposits have to be seen as the sources for AMD at the present time, with a high long-term potential to produce even more AMD in the future. The socioeconomic study showed that mining provided the major source of income. Over 45% of the households were partly or completely reliant on financial compensations as a result of mine closure. Unemployment was considered by the majority of the interviewed persons as the main cause of social problems in the area. The estimation of the explanatory factors by the logistic regression analysis revealed that education, household income, pollution conditions during the last years and familiarity with environmental problems were the main predictors influencing peoples' opinion concerning whether the main river is strongly polluted. This model enabled one to predict correctly 77% of the observations reported. For the drinking water quality model, three predictors were relevant and they explained 66% of the observations. Coupling the findings from the natural science and socioeconomic approaches, we may conclude that the impact of mining on the Certej River water is high, while drinking water in wells is not significantly affected. The perceptions of the respondents to pollution were to a large extent consistent with the measured results. The results of the study can be used by various stakeholders, mainly the mining company and local municipalities, in order to integrate them in their post-mining measures, thereby making them aware of the potential long-term impact of mining on the environment and on human health as well as on the local economy.

A Revised Hemodynamic Theory of Age-Related Macular Degeneration

PubMed Central

Gelfand, Bradley D.; Ambati, Jayakrishna

2016-01-01

Age-related macular degeneration (AMD) afflicts one out of every 40 individuals worldwide, causing irreversible central blindness in millions. The transformation of various tissue layers within the macula in the retina has led to competing conceptual models of the molecular pathways, cell types, and tissues responsible for the onset and progression of AMD. A model that has persisted for over 6 decades is the hemodynamic, or vascular theory of AMD progression, which states that vascular dysfunction of the choroid underlies AMD pathogenesis. Here, we re-evaluate this hypothesis in light of recent advances on molecular, anatomic, and hemodynamic changes underlying choroidal dysfunction in AMD. We propose an updated, detailed model of hemodynamic dysfunction as a mechanism of AMD development and progression. PMID:27423265

The construction technology of Chinese ancient city drainage facilities

NASA Astrophysics Data System (ADS)

Hequn, Li; Yufengyun

2018-03-01

In ancient china, according to the local natural environment, a variety of drainage facilities were built in order to excrete rainwater, domestic sewage, production wastewater and so on. These drainage facilities were mainly made of pottery, bricks, wood, stone, etc. For example, ceramic water pipelines, buried in the ground, connect together one by one, and there was a slight drop from one end to the other in favor of drainage. These measures can also be used for reference in today’s urban drainage and flood control.

Potential public health impact of Age-Related Eye Disease Study results: AREDS report no. 11.

PubMed

Bressler, Neil M; Bressler, Susan B; Congdon, Nathan G; Ferris, Frederick L; Friedman, David S; Klein, Ronald; Lindblad, Anne S; Milton, Roy C; Seddon, Johanna M

2003-11-01

To estimate the potential public health impact of the findings of the Age-Related Eye Disease Study (AREDS) on reducing the number of persons developing advanced age-related macular degeneration (AMD) during the next 5 years in the United States. The AREDS clinical trial provides estimates of AMD progression rates and of reduction in risk of developing advanced AMD when a high-dose nutritional supplement of antioxidants and zinc is used. These results are applied to estimates of the US population at risk, to estimate the number of people who would potentially avoid advanced AMD during 5 years if those at risk were to take a supplement such as that used in AREDS. An estimated 8 million persons at least 55 years old in the United States have monocular or binocular intermediate AMD or monocular advanced AMD. They are considered to be at high risk for advanced AMD and are those for whom the AREDS formulation should be considered. Of these people, 1.3 million would develop advanced AMD if no treatment were given to reduce their risk. If all of these people at risk received supplements such as those used in AREDS, more than 300,000 (95% confidence interval, 158,000-487,000) of them would avoid advanced AMD and any associated vision loss during the next 5 years. If people at high risk for advanced AMD received supplements such as those suggested by AREDS results, the potential impact on public health in the United States would be considerable during the next 5 years.

A thermographic study on eyes affected by Age-related Macular Degeneration: Comparison among various forms of the pathology and analysis of risk factors

NASA Astrophysics Data System (ADS)

Matteoli, Sara; Finocchio, Lucia; Biagini, Ilaria; Giacomelli, Giovanni; Sodi, Andrea; Corvi, Andrea; Virgili, Gianni; Rizzo, Stanislao

2016-05-01

The aims of this study are to investigate (1) the ocular thermographic profiles in eyes affected by Age related Macular Degeneration (AMD) and age-matched controls to detect possible hemodynamic abnormalities that could be involved in the pathogenesis of the disease, (2) whether any risk factors associated with the disease could affect the development of a form of AMD rather than another. Thirty-four eyes with Age-Related Maculopathy (ARM), 41 eyes with dry AMD, 60 eyes affected by wet AMD, and 74 eyes with fibrotic AMD were included in the study. The control group consisted of 48 healthy eyes. Exclusion criteria were represented by any other ocular diseases other than AMD, tear film abnormalities, systemic cardiovascular abnormalities, systemic diseases and a body temperature higher than 37.5 °C. A total of 210 eyes without pupil dilation were investigated by infrared thermography (FLIR A320). The Ocular Surface Temperature (OST) of five ocular areas was calculated by means of an image processing technique from the infrared images. Two-sample t-test, one-way ANOVA test and multivariate analysis were used for statistical analyses. ANOVA analyses showed no significant differences among AMD groups (P-value > 0.05), however, OST in AMD patients was significantly lower than in controls (P-value < 0.0001). Smokers showed higher possibility (P-value = 0.012) of developing wet AMD instead of dry AMD. Infrared thermography may be a helpful, non-invasive and not time-consuming method to be used in the management of patients with this common degenerative maculopathy.

Novel grid combined with peripheral distortion correction for ultra-widefield image grading of age-related macular degeneration

PubMed Central

Mach, Steven; Garas, Shady; Kim, Ivana K; Vavvas, Demetrios G; Miller, Joan W; Husain, Deeba; Miller, John B

2017-01-01

Purpose Eyes with age-related macular degeneration (AMD) often harbor pathological changes in the retinal periphery and perimacular region. These extramacular changes have not been well classified, but may be phenotypically and functionally relevant. The purpose of this study was to demonstrate a novel grid to systematically study peripheral retinal abnormalities in AMD using geometric distortion-corrected ultra-widefield (UWF) imaging. Methods This is a cross-sectional observational case series. Consecutive patients with AMD without any other coexisting vitreoretinal disease and control patients over age 50 without AMD or any other vitreoretinal disease were imaged using Optos 200 Tx. Captured 200° UWF images were corrected for peripheral geometric distortion using Optos transformation software. A newly developed grid to study perimacular and peripheral abnormalities in AMD was then projected onto the images. Results Peripheral and perimacular changes such as drusen, retinal pigment epithelium changes and atrophy were found in patients with AMD. The presented grid in conjunction with geometric distortion-corrected UWF images allowed for systematic study of these peripheral changes in AMD. Conclusion We present a novel grid to study peripheral and posterior pole changes in AMD. The grid is unique in that it adds a perimacular zone, which may be important in characterizing certain phenotypes in AMD. Our UWF images were corrected for geometric peripheral distortion to accurately reflect the anatomical dimensions of the retina. This grid offers a reliable and reproducible foundation for the exploration of peripheral retinal pathology associated with AMD. PMID:29184386

Symptoms of anxiety and mood disturbance alter cardiac and peripheral autonomic control in patients with metabolic syndrome.

PubMed

Toschi-Dias, Edgar; Trombetta, Ivani C; da Silva, Valdo José Dias; Maki-Nunes, Cristiane; Alves, Maria Janieire N N; Angelo, Luciana F; Cepeda, Felipe X; Martinez, Daniel G; Negrão, Carlos Eduardo; Rondon, Maria Urbana P B

2013-03-01

Previous investigations show that metabolic syndrome (MetSyn) causes sympathetic hyperactivation. Symptoms of anxiety and mood disturbance (AMd) provoke sympatho-vagal imbalance. We hypothesized that AMd would alter even further the autonomic function in patients with MetSyn. Twenty-six never-treated patients with MetSyn (ATP-III) were allocated to two groups, according to the levels of anxiety and mood disturbance: (1) with AMd (MetSyn + AMd, n = 15), and (2) without AMd (MetSyn, n = 11). Ten healthy control subjects were also studied (C, n = 10). AMd was determined using quantitative questionnaires. Muscle sympathetic nerve activity (MSNA, microneurography), blood pressure (oscillometric beat-to-beat basis), and heart rate (ECG) were measured during a baseline 10-min period. Spectral analysis of RR interval and systolic arterial pressure were analyzed, and the power of low (LF) and high (HF) frequency bands were determined. Sympatho-vagal balance was obtained by LF/HF ratio. Spontaneous baroreflex sensitivity (BRS) was evaluated by calculation of α-index. MSNA was greater in patients with MetSyn + AMd compared with MetSyn and C. Patients with MetSyn + AMd showed higher LF and lower HF power compared with MetSyn and C. In addition, LF/HF balance was higher in MetSyn + AMd than in MetSyn and C groups. BRS was decreased in MetSyn + AMd compared with MetSyn and C groups. Anxiety and mood disturbance alter autonomic function in patients with MetSyn. This autonomic dysfunction may contribute to the increased cardiovascular risk observed in patients with mood alterations.

Cosegregation and functional analysis of mutant ABCR (ABCA4) alleles in families that manifest both Stargardt disease and age-related macular degeneration.

PubMed

Shroyer, N F; Lewis, R A; Yatsenko, A N; Wensel, T G; Lupski, J R

2001-11-01

Mutations in ABCR (ABCA4) have been reported to cause a spectrum of autosomal recessively inherited retinopathies, including Stargardt disease (STGD), cone-rod dystrophy and retinitis pigmentosa. Individuals heterozygous for ABCR mutations may be predisposed to develop the multifactorial disorder age-related macular degeneration (AMD). We hypothesized that some carriers of STGD alleles have an increased risk to develop AMD. We tested this hypothesis in a cohort of families that manifest both STGD and AMD. With a direct-sequencing mutation detection strategy, we found that AMD-affected relatives of STGD patients are more likely to be carriers of pathogenic STGD alleles than predicted based on chance alone. We further investigated the role of AMD-associated ABCR mutations by testing for expression and ATP-binding defects in an in vitro biochemical assay. We found that mutations associated with AMD have a range of assayable defects ranging from no detectable defect to apparent null alleles. Of the 21 missense ABCR mutations reported in patients with AMD, 16 (76%) show abnormalities in protein expression, ATP-binding or ATPase activity. We infer that carrier relatives of STGD patients are predisposed to develop AMD.

Crystal structure and superconductivity in atomic hydrogen: Deformation between I41/amd and Fddd

NASA Astrophysics Data System (ADS)

Ishikawa, T.; Nagara, H.; Oda, T.; Suzuki, N.; Shimizu, K.

2017-10-01

We investigated crystal structures of solid metallic hydrogen using the potential energy surface trekking for structure search. We applied this technique to a tetragonal I41/amd structure at pressures of 500 and 600 GPa and obtained the transformation into multiple orthorhombic Fddd structures, which are formed by distortions in the ab plane of I41/amd. The potential barriers are easily surmounted by few trekking steps, which indicates that in solid metallic hydrogen crystal structure is softened with respect to the distortion and is easily fluctuated among the I41/amd and Fddd structures. Calculated superconducting critical temperatures show 269 K for I41/amd and 263 K for Fddd at 500 GPa. The structures are softened and the electron-phonon coupling are enhanced with pressurization to 600 GPa. As the results, the superconducting critical temperature is increased to 281 K for I41/amd, whereas it is decreased to 252 K for Fddd owing to its larger phonon softening than that of I41/amd.

Ranibizumab for the treatment of neovascular AMD.

PubMed

Kaiser, P K; Do, D V

2007-03-01

Age-related macular degeneration (AMD) is the leading cause of adult blindness among individuals aged 50 and older in the Western world, with the neovascular form of AMD responsible for the most severe and rapid visual loss. Although monotherapy with currently available treatments can slow the rate of loss of vision in eyes with neovascular AMD, they do not significantly improve vision. Vascular endothelial growth factor-A (VEGF-A) plays a critical role in the pathogenesis of neovascular AMD, and ranibizumab is a promising new treatment that targets all VEGF-A isoforms and their biologically active degradation products. Clinical trials have reported that ranibizumab treatment resulted in greater proportions of patients achieving a < 15 letter loss of visual acuity and improved vision at 12 and 24 months than control groups. The incidence of serious ocular and systemic adverse events was low in all ranibizumab trials to date. Currently, ranibizumab is the only treatment for neovascular AMD to demonstrate significant improvement in vision for many patients and represents a major advance in treating neovascular AMD.

Nutrition and age-related macular degeneration: research evidence in practice.

PubMed

Downie, Laura Elizabeth; Keller, Peter Richard

2014-08-01

Age-related macular degeneration (AMD) is the leading cause of irreversible visual impairment in developed countries. In the absence of effective treatments to slow AMD progression, it is predicted that the prevalence of AMD will double over the next 20 years. One area of significant interest is the potential role that nutrition may play in preventing and/or delaying the progression of AMD. Specifically, is there any benefit in oral antioxidant and/or mineral supplementation? This review critically evaluates the currently available evidence relating to nutrition and AMD, with particular reference to the key findings of two large National Eye Institute-sponsored clinical studies, namely, the Age-Related Eye Disease Study (AREDS) and AREDS2. Topical controversies relating to nutrition and AMD are considered and analyzed in the context of the published literature to guide practitioners through assessing the merit, or otherwise, of common claims. This article provides a foundation for clinicians to provide informed advice to AMD patients based on available research evidence.

Application of a systemic approach to the study of pollution of the Tinto and Odiel rivers (Spain).

PubMed

Sainz, A; Grande, J A; De La Torre, M L

2005-03-01

The province of Huelva in the SW of Spain presents high environmental contrasts: together with the great abundance of natural spaces, it shows the impacts of historical natural resources exploitation processes. In the Ria of Huelva, the effluents of the chemical industries must be added to the contaminating inputs of the Tinto and Odiel rivers, coming from the acid drainage of the mines located in the Iberian Pyrite Belt. This forced the Environmental Agency (AMA) to elaborate in 1987 an Effluent Remediation Plan in order to negate unacceptable environmental impacts. The application of a "grey box" systemic analysis to the AMD pollution, undergone by the Tinto and Odiel rivers has allowed to set a conclusive explanation of the sampling results observed for a period of 11 years, thus making available an overall view of the polluting process and, above all, an explanation of its partial aspects.

Analysis OpenMP performance of AMD and Intel architecture for breaking waves simulation using MPS

NASA Astrophysics Data System (ADS)

Alamsyah, M. N. A.; Utomo, A.; Gunawan, P. H.

2018-03-01

Simulation of breaking waves by using Navier-Stokes equation via moving particle semi-implicit method (MPS) over close domain is given. The results show the parallel computing on multicore architecture using OpenMP platform can reduce the computational time almost half of the serial time. Here, the comparison using two computer architectures (AMD and Intel) are performed. The results using Intel architecture is shown better than AMD architecture in CPU time. However, in efficiency, the computer with AMD architecture gives slightly higher than the Intel. For the simulation by 1512 number of particles, the CPU time using Intel and AMD are 12662.47 and 28282.30 respectively. Moreover, the efficiency using similar number of particles, AMD obtains 50.09 % and Intel up to 49.42 %.

Brueckner-AMD Study of Light Nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kato, Kiyoshi; Yamamoto, Yuhei; Togashi, Tomoaki

2011-06-28

We applied the Brueckner theory to the Antisymmetrized Molecular Dynamics (AMD) and examined the reliability of the AMD calculations based on realistic nuclear interactions. In this method, the Bethe-Goldstone equation in the Brueckner theory is solved for every nucleon pair described by wave packets of AMD, and the G-matrix is calculated with single-particle orbits in AMD self-consistently. We apply this framework to not only {alpha}-nuclei but also N{ne}Z nuclei with A{approx}10. It is confirmed that these results present the description of reasonable cluster structures and energy-level schemes comparable with the experimental ones in light nuclei.

Natural history of drusenoid pigment epithelial detachment in age-related macular degeneration: Age-Related Eye Disease Study Report No. 28.

PubMed

Cukras, Catherine; Agrón, Elvira; Klein, Michael L; Ferris, Frederick L; Chew, Emily Y; Gensler, Gary; Wong, Wai T

2010-03-01

To describe the natural history of eyes with drusenoid pigment epithelial detachments (DPEDs) associated with age-related macular degeneration (AMD). Multicenter, clinic-based, prospective cohort study. Among 4757 participants enrolled in the Age-Related Eye Disease Study (AREDS), 255 were identified as having DPED in at least 1 eye and having 5 or more years of follow-up after the initial detection of the DPED. Baseline and annual fundus photographs were evaluated for the evolution of the fundus features and the development of advanced AMD in the forms of central geographic atrophy (CGA) or neovascular (NV) AMD. Kaplan-Meier analyses of progression to advanced AMD and of moderate vision loss (> or =15 letters compared with baseline) were performed. Rate of progression to advanced AMD and change in visual acuity from baseline (in terms of mean letters lost and proportion losing > or =15 letters). A total of 311 eyes (from 255 participants) with DPED were followed for a median follow-up time of 8 years subsequent to the initial detection of a DPED. Of the 282 eyes that did not have advanced AMD at baseline, advanced AMD developed within 5 years in 119 eyes (42%) (19% progressing to CGA and 23% progressing to NV-AMD). In the remaining eyes that did not develop advanced AMD (n=163), progressive fundus changes, typified by the development of calcified drusen and pigmentary changes, were detected. Visual decline was prominent among study eyes, with approximately 40% of all eyes decreasing in visual acuity by > or =15 letters at 5 years follow-up. Mean visual acuity decreased from 76 letters ( approximately 20/30) at baseline to 61 letters ( approximately 20/60) at 5 years. Five-year decreases in mean visual acuity averaged 26 letters for eyes progressing to advanced AMD and 8 letters for non-progressing eyes. The natural history of eyes containing DPED is characterized by a high rate of progression to both CGA and NV-AMD. Among eyes not progressing to advanced AMD, progressive development of pigmentary changes and calcified drusen were observed. Decline of visual acuity is a common outcome, with or without progression to advanced forms of AMD. Copyright 2010 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Retinal Spectral Domain Optical Coherence Tomography in Early Atrophic Age-Related Macular Degeneration (AMD) and a New Metric for Objective Evaluation of the Efficacy of Ocular Nutrition

PubMed Central

Richer, Stuart; Cho, Jane; Stiles, William; Levin, Marc; Wrobel, James S.; Sinai, Michael; Thomas, Carla

2012-01-01

Purpose: A challenge in ocular preventive medicine is identification of patients with early pathological retinal damage that might benefit from nutritional intervention. The purpose of this study is to evaluate retinal thinning (RT) in early atrophic age-related macular degeneration (AMD) against visual function data from the Zeaxanthin and Visual Function (ZVF) randomized double masked placebo controlled clinical trial (FDA IND #78973). Methods: Retrospective, observational case series of medical center veterans with minimal visible AMD retinopathy (AREDS Report #18 simplified grading 1.4/4.0 bilateral retinopathy). Foveal and extra-foveal four quadrant SDOCT RT measurements were evaluated in n = 54 clinical and ZVF AMD patients. RT by age was determined and compared to the OptoVue SD OCT normative database. RT by quadrant in a subset of n = 29 ZVF patients was correlated with contrast sensitivity and parafoveal blue cone increment thresholds. Results: Foveal RT in AMD patients and non-AMD patients was preserved with age. Extrafoveal regions, however, showed significant slope differences between AMD patients and non-AMD patients, with the superior and nasal quadrants most vulnerable to retinal thinning (sup quad: −5.5 μm/decade thinning vs. Non-AMD: −1.1 μm/decade, P < 0.02; nasal quad: −5.0 μm/decade thinning vs. Non-AMD: −1.0 μm/decade, P < 0.04). Two measures of extrafoveal visual deterioration were correlated: A significant inverse correlation between % RT and contrast sensitivity (r = −0.33, P = 0.01, 2 Tailed Paired T) and an elevated extrafoveal increment blue cone threshold (r = +0.34, P = 0.01, 2 Tailed T). Additional SD OCT RT data for the non-AMD oldest age group (ages 82–91) is needed to fully substantiate the model. Conclusion: A simple new SD OCT clinical metric called “% extra-foveal RT” correlates well with functional visual loss in early AMD patients having minimal visible retinopathy. This metric can be used to follow the effect of repleting ocular nutrients, such as zinc, antioxidants, carotenoids, n-3 essential fats , resveratrol and vitamin D. PMID:23363992

The Association of Statin Use with Age-Related Macular Degeneration Progression: The Age-Related Eye Disease Study 2 Report Number 9.

PubMed

Al-Holou, Shaza N; Tucker, William R; Agrón, Elvira; Clemons, Traci E; Cukras, Catherine; Ferris, Frederick L; Chew, Emily Y

2015-12-01

To evaluate the association of statin use with progression of age-related macular degeneration (AMD). Preplanned, prospective cohort study within a controlled clinical trial of oral supplementation for age-related eye diseases. Age-Related Eye Disease Study 2 (AREDS2) participants, aged 50 to 85 years. Factors, including age, gender, smoking status, aspirin use, and history of diabetes, hypertension, heart disease, angina, and stroke-all known to be associated with statin use-were included in a logistic regression model to estimate propensity scores for each participant. Age-adjusted proportional hazards regression models, with and without propensity score matching, were performed to evaluate the association of statin use with progression to late AMD. Analyses adjusting for the competing risk of death were also performed. Baseline and annual stereoscopic fundus photographs were assessed centrally by masked graders for the development of late AMD, either neovascular AMD or geographic atrophy (GA). Of the 3791 participants (2462 with bilateral large drusen and 1329 with unilateral late AMD at baseline), 1659 (43.8%) were statin users. The overall analysis, with no matching of propensity scores and no adjustment for death as a competing risk, showed that statin use was not associated with progression to late AMD (hazard ratio [HR], 1.08; 95% confidence interval [CI], 0.83-1.41; P = 0.56). When matched for propensity scores and adjusted for death as a competing risk, the result was not statistically significant (HR, 0.81; 95% CI, 0.55-1.20; P = 0.29). Furthermore, subgroup analyses of persons with or without late AMD at baseline and the various components of late AMD (neovascular AMD, central GA, or any GA) also showed no statistically significant association of statin use with progression to AMD. Statin use was not statistically significantly associated with progression to late AMD in the AREDS2 participants, and these findings are consistent with findings in the majority of previous studies. Statins have been demonstrated to reduce the risk of cardiovascular disease, but our data do not provide evidence of a beneficial effect on slowing AMD progression. Published by Elsevier Inc.

HUMAN HtrA1 IN THE ARCHIVED EYES WITH AGE-RELATED MACULAR DEGENERATION

PubMed Central

Chan, Chi-Chao; Shen, Defen; Zhou, Min; Ross, Robert J.; Ding, Xiaoyan; Zhang, Kang; Green, W. Richard; Tuo, Jingsheng

2007-01-01

Purpose HtrA1 belongs to the high temperature requirement factor A family of serine proteases, which are involved in protein quality control and cell fate. A single-nucleotide polymorphism (SNP), rs11200638, in the promoter of HtrA1 at chromosome 10q26 is reported as a likely causal variant for age-related macular degeneration (AMD). The SNP is located in the regulatory region and increases production of HtrA1 protein. This study investigates HtrA1 expression and SNP genotypes in archived ocular slides with AMD. Methods Macular, nonretinal, and peripheral retinal cells were microdissected from archived slides from 57 eyes with AMD and 16 age-matched, non-AMD controls. HtrA1 rs11200638 SNP genotyping was performed using polymerase chain reaction (PCR) and restriction fragment length polymorphism analysis. HtrA1 transcripts were measured using real-time reverse transcriptase–PCR. HtrA1 protein expression was evaluated using avidin-biotin complex immunohistochemistry. Results HtrA1 (G/A) SNP was successfully genotyped in 52 AMD cases and 13 non-AMD subjects. The frequencies of the risk allele (A) were 55 of 104 (52.9%) and 8 of 26 (30.8%) in AMD and control groups, respectively. HtrA1 mRNA was detected in normal peripheral and macular retinas, higher in the periphery than maculae. HtrA1 mRNA was much higher in the macula and a lot lower in the periphery of the AMD eyes as compared to control eyes. HtrA1 protein was expressed in normal retinal vascular endothelia and retinal pigment epithelia. Intense immunoreaction against HtrA1 was found in AMD lesions, slightly more in wet than dry AMD lesions. Conclusion This study successfully analyzes HtrA1 SNP and transcript expression in microdissected cells from archived paraffin fixed slides. Up-regulation of HtrA1 is detected in the macular lesions of AMD eyes. The data further suggest that rs11200638 in HtrA1 promoter is associated with AMD development. PMID:18427598

A prospective study of common variants in the RAR-related orphan receptor alpha (RORalpha) gene and risk of neovascular age-related macular degeneration

PubMed Central

Schaumberg, Debra A.; Chasman, Daniel; Morrison, Margaux A.; Adams, Scott M.; Guo, Qun; Hunter, David J.; Hankinson, Susan E.; DeAngelis, Margaret M.

2010-01-01

Objectives The RAR-related orphan receptor alpha (RORalpha) gene is implicated as a candidate for age-related macular degeneration (AMD) through a previous microarray expression study, linkage data, biological plausibility, and two clinic-based cross sectional studies. We aimed to determine if common variants in RORalpha predict future risk of neovascular AMD. Methods We measured genotypes for 18 variants in intron 1 of the RORalpha gene among 164 cases who developed neovascular AMD and 485 age- and sex-matched controls in a prospective nested case-control study within the Nurses’ Health Study and the Health Professionals Follow-up Study. We determined the incidence rate ratios (IRR) and 95% confidence intervals (CI) for neovascular AMD for each variant, and examined interactions with other AMD-associated variants and modifiable risk factors. Results We identified a single SNP (rs12900948) that was significantly associated with increased incidence of neovascular AMD. Participants with one and two copies of the “G” allele were 1.73 (CI= 1.32–2.27) and 2.99 (CI=1.74–5.14) times more likely to develop neovascular AMD. Individuals homozygous for both the “G” allele of rs12900948 and ARMS2 A69S had a 40.8-fold increased risk of neovascular AMD (CI=10.1–164; P for interaction=0.017). Cigarette smokers who carried two copies of the “G” allele had a 9.89-fold risk of neovascular AMD, but the interaction was not significant (P=0.08). We identified a significant AMD-associated haplotype block containing SNPs rs730754, rs8034864, and rs12900948, with P-values for ACA=1.16 × 10−9, ACG=5.85 × 10−12, and GAA=0.0001 when compared to all other haplotypes. Conclusion Common variants and haplotypes within the RORalpha gene appear to act synergistically with the ARMS2 A69S polymorphism to increase risk of neovascular AMD. These data add further evidence of a high level of complexity linking genetic and modifiable risk factors to AMD development and should help efforts at risk prediction. PMID:21060049

Five-year follow-up of low-level laser therapy (LLLT) in patients with age-related macular degeneration (AMD)

NASA Astrophysics Data System (ADS)

Koev, K.; Avramov, L.; Borissova, E.

2018-03-01

The objective of this study was to examine long-term effects of low-level laser therapy (LLLT) in patients with age-related macular degeneration (AMD). The research was implemented for a period of five years. For LLLT, a He-Ne Laser with continuous emission at 633 nm (0.1 mW/cm2) was used in patients with AMD of all stages (dry to wet exudative forms were included). In total, 33 patients (16 men and 17 women – 66 eyes) with AMD of various stages and a mean age of 68.7 ± 4.2 years were included in the study. Progressive, exudative AMD was diagnosed in 8 eyes. 58 eyes had drusen or were depigmented. Laser radiation was applied transpupillary to the macula for six times for three minutes once in two days; 22 patients with AMD (44 eyes) were randomly selected to receive mock treatment (control group 10 men and 12 women with a mean age of 69.3 ± 4.8 years). The visual acuity was followed for a five-year period. The perimetry and Amsler test were used to screen central scotomas. The fluorescein angiography of AMD and the control groups was examined. The visual acuity remained unchanged in all patients in the control group. There was a statistically significant increase in the visual acuity (p<0.001, end of study versus baseline) for AMD patients for the period of five years after the treatment. The edema and hemorrhage in the patients with progressive, exudative AMD significantly decreased. No side effects were observed during the therapy. The prevalence of metamorphopsia, scotoma in AMD group was reduced. In conclusion, this study shows that LLLT may be a novel long-lasting therapeutic option for both forms of AMD. It is a highly-effective treatment that results in a long-term improvement of the visual acuity.

A comparison of risk factors for age-related macular degeneration and polypoidal choroidal vasculopathy in Chinese patients.

PubMed

Chen, Xiao-Li; Hu, Qin-Rui; Bai, Yu-Jing; Deng, Yu; Wang, Hai-Wei; Liu, Shan; Wang, Yin-Lin; Yue, Yan-Kun

2018-06-01

Neovascular age-related macular degeneration (nAMD) and polypoidal choroidal vasculopathy (PCV) are important vision-threatening diseases worldwide. For effective treatment, the risk factors for the diseases merit investigation. This study aimed to compare the risk factors for nAMD vs. PCV in Chinese patients. A total of 946 participants were recruited in this case-control study, including 281 patients with nAMD, 306 patients with PCV, and 359 controls. All participants underwent comprehensive ophthalmic examinations. Information on risk factors were collected by questionnaire. Multivariate logistic regression analyses were performed to investigate the difference in risk factors between nAMD and PCV. In a subgroup of subjects, serum lipid data were obtained and analyzed. Risk factors for nAMD included older age (OR 1.03, P = 0.001), male gender (OR 1.55, P = 0.020), asthma (OR 2.50, P = 0.028), smoking (OR 1.92, P = 0.001), and family history (OR 6.82, P = 0.001), while smoking (OR 1.67, P = 0.013) was the only risk factor for PCV. Compared to patients with PCV, patients with nAMD were more likely to be older and suffer from hyperlipidemia, coronary artery disease, rheumatism, and tumor. Interestingly, higher levels of high-density lipoprotein were positively associated with PCV in the subgroup analysis (OR 7.74, P = 0.011). Besides, results were quite different between the combination of patients with nAMD and PCV and patients with nAMD or PCV alone. The risk factors for nAMD and PCV is varying with the exception of smoking. Our findings suggest that different strategies might be applied in the clinical management and scientific research on nAMD and PCV.

Tear film proteome in age-related macular degeneration.

PubMed

Winiarczyk, Mateusz; Kaarniranta, Kai; Winiarczyk, Stanisław; Adaszek, Łukasz; Winiarczyk, Dagmara; Mackiewicz, Jerzy

2018-06-01

Age-related macular degeneration (AMD) is the main reason for blindness in elderly people in the developed countries. Current screening protocols have limitations in detecting the early signs of retinal degeneration. Therefore, it would be desirable to find novel biomarkers for early detection of AMD. Development of novel biomarkers would help in the prevention, diagnostics, and treatment of AMD. Proteomic analysis of tear film has shown promise in this research area. If an optimal set of biomarkers could be obtained from accessible body fluids, it would represent a reliable way to monitor disease progression and response to novel therapies. Tear films were collected on Schirmer strips from a total of 22 patients (8 with wet AMD, 6 with dry AMD, and 8 control individuals). 2D electrophoresis was used to separate tear film proteins prior to their identification with matrix-assisted laser desorption/ionization time of flight spectrometer (MALDI-TOF/TOF) and matching with functional databases. A total of 342 proteins were identified. Most of them were previously described in various proteomic studies concerning AMD. Shootin-1, histatin-3, fidgetin-like protein 1, SRC kinase signaling inhibitor, Graves disease carrier protein, actin cytoplasmic 1, prolactin-inducible protein 1, and protein S100-A7A were upregulated in the tear film samples isolated from AMD patients and were not previously linked with this disease in any proteomic analysis. The upregulated proteins supplement our current knowledge of AMD pathogenesis, providing evidence that certain specific proteins are expressed into the tear film in AMD. As far we are aware, this is the first study to have undertaken a comprehensive in-depth analysis of the human tear film proteome in AMD patients.

Association of glutathione S-transferase pi isoform single-nucleotide polymorphisms with exudative age-related macular degeneration in a Chinese population.

PubMed

Gu, Hong; Sun, Erdan; Cui, Lei; Yang, Xiufen; Lim, Apiradee; Xu, Jun; Snellingen, Torkel; Liu, Xipu; Wang, Ningli; Liu, Ningpu

2012-10-01

To investigate the association between single-nucleotide polymorphisms in the pi isoform of glutathione S-transferase (GSTP1) gene and the risk of exudative age-related macular degeneration (AMD) in a Chinese case-control cohort. A total of 131 Chinese patients with exudative AMD and 138 control individuals were recruited. Genomic DNA was extracted from venous blood leukocytes. Two common nonsynonymous single-nucleotide polymorphisms in GSTP1 (rs1695 and rs1138272) were genotyped by polymerase chain reaction followed by allele-specific restriction enzyme digestion and direct sequencing. Significant association with exudative AMD was detected for single-nucleotide polymorphism, rs1695 (P = 0.019). The risk G allele frequencies were 21.8% in AMD patients and 12.7% in control subjects (P = 0.007). Compared with the wild-type AA genotype, odds ratio for the risk of AMD was 1.91 (95% confidence interval, 1.09-3.35) for the heterozygous AG genotype and 2.52 (95% confidence interval, 0.6-10.61) for the homozygous GG genotype. In contrast, rs1138272 was not associated with exudative AMD (P = 1.00). The risk G allele frequencies of rs1138272 were 0.4% in AMD patients and 0.4% in control subjects (P = 1.00). Our data suggest that the GSTP1 variant rs1695 moderately increases the risk of exudative AMD. The variant rs1138272 was rare and was not associated with exudative AMD in this Chinese cohort.

HEALTH CONDITIONS LINKED TO AGE-RELATED MACULAR DEGENERATION ASSOCIATED WITH DARK ADAPTATION.

PubMed

Laíns, Inês; Miller, John B; Mukai, Ryo; Mach, Steven; Vavvas, Demetrios; Kim, Ivana K; Miller, Joan W; Husain, Deeba

2018-06-01

To determine the association between dark adaption (DA) and different health conditions linked with age-related macular degeneration (AMD). Cross-sectional study, including patients with AMD and a control group. Age-related macular degeneration was graded according to the Age-Related Eye Disease Study (AREDS) classification. We obtained data on medical history, medications, and lifestyle. Dark adaption was assessed with the extended protocol (20 minutes) of AdaptDx (MacuLogix). For analyses, the right eye or the eye with more advanced AMD was selected. Multivariate linear and logistic regressions were performed, accounting for age and AMD stage. Seventy-eight subjects (75.6% AMD; 24.4% controls) were included. Multivariate assessments revealed that body mass index (BMI; β = 0.30, P = 0.045), taking AREDS vitamins (β = 5.51, P < 0.001), and family history of AMD (β = 2.68, P = 0.039) were significantly associated with worse rod intercept times. Abnormal DA (rod intercept time ≥ 6.5 minutes) was significantly associated with family history of AMD (β = 1.84, P = 0.006), taking AREDS supplements (β = 1.67, P = 0.021) and alcohol intake (β = 0.07, P = 0.017). Besides age and AMD stage, a higher body mass index, higher alcohol intake, and a family history of AMD seem to impair DA. In this cohort, the use of AREDS vitamins was also statistically linked with impaired DA, most likely because of an increased severity of disease in subjects taking them.

Baseline data from a multicenter, 5-year, prospective cohort study of Japanese age-related macular degeneration: an AMD2000 report.

PubMed

Tsujikawa, Akitaka; Akagi-Kurashige, Yumiko; Yuzawa, Mitsuko; Ishibashi, Tatsuro; Nakanishi, Hideo; Nakatani, Eiji; Teramukai, Satoshi; Fukushima, Masanori; Yoshimura, Nagahisa

2018-03-01

To report research participants' baseline characteristics in the AMD2000 study, a prospective, multicenter, 5-year, observational cohort study of Japanese age-related macular degeneration (AMD). The characteristics were determined using multimodal imaging. Patients with AMD were recruited at 18 clinical sites in Japan between April 2006 and March 2009. Each patient underwent a complete ophthalmic examination, including measurement of best-corrected visual acuity (Landolt chart), indirect ophthalmoscopy, slit-lamp biomicroscopy with a contact lens, optical coherence tomography imaging, fundus photography, and fluorescein and indocyanine green angiography. Four hundred sixty participants (326 men [70.9%]) were included in the study. At enrollment, 131 eyes (28.5%) had hard drusen and 125 eyes (27.2%) had soft drusen in the macular area. A total of 455 eyes (98.9%) were diagnosed as having wet AMD, and 5 eyes (1.1%), as having dry AMD. Of the 455 eyes with wet AMD, 209 eyes (45.4%) had typical AMD, 228 eyes (49.6%) had polypoidal choroidal vasculopathy (PCV), and 18 eyes (3.9%) had retinal angiomatous proliferation. The size of choroidal neovascularization (CNV) was significantly smaller with indocyanine green angiography than with fluorescein angiography (P < 0.001). Poor baseline visual acuity was associated with cystoid macular edema, older age, scar, extrafoveal macular edema, subfoveal CNV, large branching vascular network, and hard exudates. Japanese patients with AMD are predominantly male, lack drusen, and have a high rate of PCV.

The genetics of age-related macular degeneration (AMD)--Novel targets for designing treatment options?

PubMed

Grassmann, Felix; Fauser, Sascha; Weber, Bernhard H F

2015-09-01

Age-related macular degeneration (AMD) is a progressive disease of the central retina and the main cause of legal blindness in industrialized countries. Risk to develop the disease is conferred by both individual as well as genetic factors with the latter being increasingly deciphered over the last decade. Therapeutically, striking advances have been made for the treatment of the neovascular form of late stage AMD while for the late stage atrophic form of the disease, which accounts for almost half of the visually impaired, there is currently no effective therapy on the market. This review highlights our current knowledge on the genetic architecture of early and late stage AMD and explores its potential for the discovery of novel, target-guided treatment options. We reflect on current clinical and experimental therapies for all forms of AMD and specifically note a persisting lack of efficacy for treatment in atrophic AMD. We further explore the current insight in AMD-associated genes and pathways and critically question whether this knowledge is suited to design novel treatment options. Specifically, we point out that known genetic factors associated with AMD govern the risk to develop disease and thus may not play a role in its severity or progression. Treatments based on such knowledge appear appropriate rather for prevention than treatment of manifest disease. As a consequence, future research in AMD needs to be greatly focused on approaches relevant to the patients and their medical needs. Copyright © 2015 Elsevier B.V. All rights reserved.

Review of nutrient actions on age-related macular degeneration.

PubMed

Zampatti, Stefania; Ricci, Federico; Cusumano, Andrea; Marsella, Luigi Tonino; Novelli, Giuseppe; Giardina, Emiliano

2014-02-01

The actions of nutrients and related compounds on age-related macular degeneration (AMD) are explained in this review. The findings from 80 studies published since 2003 on the association between diet and supplements in AMD were reviewed. Antioxidants and other nutrients with an effect on AMD susceptibility include carotenoids (lutein and zeaxanthin, β-carotene), vitamins (vitamin A, E, C, D, B), mineral supplements (zinc, copper, selenium), dietary fatty acids [monounsaturated fatty acids, polyunsaturated fatty acids (PUFA both omega-3 PUFA and omega-6 PUFA), saturated fatty acids and cholesterol], and dietary carbohydrates. The literature revealed that many of these antioxidants and nutrients exert a protective role by functioning synergistically. Specifically, the use of dietary supplements with targeted actions can provide minimal benefits on the onset or progression of AMD; however, this does not appear to be particularly beneficial in healthy people. Furthermore, some supplements or nutrients have demonstrated discordant effects on AMD in some studies. Since intake of dietary supplements, as well as exposure to damaging environmental factors, is largely dependent on population habits (including dietary practices) and geographical localization, an overall healthy diet appears to be the best strategy in reducing the risk of developing AMD. As of now, the precise mechanism of action of certain nutrients in AMD prevention remains unclear. Thus, future studies are required to examine the effects that nutrients have on AMD and to determine which factors are most strongly correlated with reducing the risk of AMD or preventing its progression. Copyright © 2014 Elsevier Inc. All rights reserved.

Enabling Computational Dynamics in Distributed Computing Environments Using a Heterogeneous Computing Template

DTIC Science & Technology

2011-08-09

fastest 10 supercomputers in the world. Both systems rely on GPU co-processing, one using AMD cards, the second, called Nebulae , using NVIDIA Tesla...Page 9 of 10 UNCLASSIFIED capability of almost 3 petaflop/s, the highest in TOP500, Nebulae only holds the No. 2 position on the TOP500 list of the

Quantifying Fenton reaction pathways driven by self-generated H2O2 on pyrite surfaces.

PubMed

Gil-Lozano, C; Davila, A F; Losa-Adams, E; Fairén, A G; Gago-Duport, L

2017-03-06

Oxidation of pyrite (FeS 2 ) plays a significant role in the redox cycling of iron and sulfur on Earth and is the primary cause of acid mine drainage (AMD). It has been established that this process involves multi-step electron-transfer reactions between surface defects and adsorbed O 2 and H 2 O, releasing sulfoxy species (e.g., S 2 O 3 2- , SO 4 2- ) and ferrous iron (Fe 2+ ) to the solution and also producing intermediate by-products, such as hydrogen peroxide (H 2 O 2 ) and other reactive oxygen species (ROS), however, our understanding of the kinetics of these transient species is still limited. We investigated the kinetics of H 2 O 2 formation in aqueous suspensions of FeS 2 microparticles by monitoring, in real time, the H 2 O 2 and dissolved O 2 concentration under oxic and anoxic conditions using amperometric microsensors. Additional spectroscopic and structural analyses were done to track the dependencies between the process of FeS 2 dissolution and the degradation of H 2 O 2 through the Fenton reaction. Based on our experimental results, we built a kinetic model which explains the observed trend of H 2 O 2 , showing that FeS 2 dissolution can act as a natural Fenton reagent, influencing the oxidation of third-party species during the long term evolution of geochemical systems, even in oxygen-limited environments.

Complement pathway biomarkers and age-related macular degeneration

PubMed Central

Gemenetzi, M; Lotery, A J

2016-01-01

In the age-related macular degeneration (AMD) ‘inflammation model', local inflammation plus complement activation contributes to the pathogenesis and progression of the disease. Multiple genetic associations have now been established correlating the risk of development or progression of AMD. Stratifying patients by their AMD genetic profile may facilitate future AMD therapeutic trials resulting in meaningful clinical trial end points with smaller sample sizes and study duration. PMID:26493033

Visual, Musculoskeletal, and Balance Complaints in AMD: A Follow-Up Study

PubMed Central

Richter, Hans Olof

2016-01-01

Purpose. To investigate whether patients with age-related macular degeneration (AMD) run a potentially higher risk of developing visual, musculoskeletal, and balance complaints than age-matched controls with normal vision. Methods. Visual assessments, self-rated visual function, self-rated visual, musculoskeletal, and balance complaints, and perceived general health were obtained in 37 AMD patients and 18 controls, at baseline and after an average of 3.8 years later. Results. At follow-up both groups reported decreased visual acuity (VA) and visual function, but only AMD patients reported significantly increased visual, musculoskeletal, and balance complaints. Decreased VA, need for larger font size when reading, need for larger magnification, and decreased self-rated visual function were identified as risk markers for increased complaints in AMD patients. These complaints were also identified as risk markers for decreased health. For controls, decreased VA and self-reported visual function were associated with increased visual and balance complaints. Conclusions. Visual deterioration was a risk marker for increased visual, musculoskeletal, balance, and health complaints in AMD patients. Specifically, magnifying visual aids, such as CCTV, were a risk marker for increased complaints in AMD patients. This calls for early and coordinated actions to treat and prevent visual, musculoskeletal, balance, and health complaints in AMD patients. PMID:27830084

Photometric Evaluation of Soft Tissue Changes in CLP Patients: Le Fort I Advancement Osteotomy (ALO) Versus Anterior Maxillary Distraction (AMD).

PubMed

Paulose, Joby; Markose, Eldho

2014-12-01

This paper is a comparative photometric evaluation of soft tissue changes in patients with CLP associated with maxillary deficiency treated with conventional Le Fort I advancement osteotomy (ALO) and anterior maxillary distraction (AMD). Twenty patients with maxillary hypoplasia associated with cleft lip and palate who had undergone either LeFort I osteotomy or distraction osteogenesis with maxillary advancement were included in this study. Frontal and profile photographs were used to ascertain the changes post-surgically. Photographs were obtained before treatment and 1 year after surgical correction in both groups. Vertical as well as horizontal changes in pronasale was well observed in both groups. A substantial increase in nasal parameters was noted in case of AMD group in comparison to ALO group. Though maxillary advancement was quite evident in AMD and ALO groups, a significant and consistent change was observed in AMD group. Significant vertical and horizontal changes were seen with respect to subnasale and labrale superius in AMD group. The hard and soft tissue changes produced by AMD by intra oral distractors were being evaluated so far. The results of the above studies have proved the excellence of AMD over conventional osteotomies. The present study goes hand in hand with the research outcomes till date.

Population-based incidence of exudative age-related macular degeneration and ranibizumab treatment load.

PubMed

Geirsdottir, Asbjorg; Jonsson, Oskar; Thorisdottir, Sigridur; Helgadottir, Gudleif; Jonasson, Fridbert; Stefansson, Einar; Sigurdsson, Haraldur

2012-03-01

The use of intravitreal vascular endothelial growth factor antibodies for exudative age-related macular degeneration (AMD) has stressed ophthalmology services and drug budgets throughout the world. The authors study the population-based incidence of exudative AMD in Iceland and the use of intravitreal ranibizumab in a defined population. This is a prospective study of 439 consecutive patients aged 60 years and older with exudative AMD starting intravitreal ranibizumab for exudative AMD in Iceland from March 2007 to December 2009. All patients initially received three consecutive ranibizumab injections, with regular follow-up visits and re-treatment as needed. In total, 517 eyes from 439 patients received treatment for exudative AMD (mean age 79 years). The annual incidence of exudative AMD in the population 60 years and older is 0.29%. The incidence increased with advancing age, double for patients 85 years and older compared with those 75-79 years. Approximately 2400 ranibizumab injections per 100,000 persons aged 60 years and older were given each year for exudative AMD. These data allow an estimation of the incidence of exudative AMD in a Caucasian population and the treatment load with ranibizumab, which may help plan anti-vascular endothelial growth factor treatment programmes and estimate costs.

Plasma Homocysteine and Asymmetrical Dimethyl-l-Arginine (ADMA) and Whole Blood DNA Methylation in Early and Neovascular Age-Related Macular Degeneration: A Pilot Study.

PubMed

Pinna, Antonio; Zinellu, Angelo; Tendas, Donatella; Blasetti, Francesco; Carru, Ciriaco; Castiglia, Paolo

2016-01-01

To compare the plasma levels of homocysteine and asymmetrical dimethyl-l-arginine (ADMA) and the degree of whole blood DNA methylation in patients with early and neovascular age-related macular degeneration (AMD) and in controls without maculopathy of any sort. This observational case-control pilot study included 39 early AMD patients, 27 neovascular AMD patients and 132 sex- and age-matched controls without maculopathy. Plasma homocysteine and ADMA concentrations and the degree of whole blood DNA methylation were measured. Quantitative variables were compared by Student's t-test or Mann-Whitney test. Logistic regression models were used to investigate the significance of the association between early or wet AMD and some variables. There were no significant differences in mean plasma homocysteine and ADMA concentrations and in the degree of whole blood DNA methylation between patients with early or neovascular AMD and their controls. Similarly, logistic regression analysis disclosed that plasma homocysteine and ADMA levels were not associated with an increased risk for early or neovascular AMD. We failed to demonstrate an association between early or neovascular AMD and increased plasma homocysteine and/or ADMA. Results also suggest that the degree of whole blood DNA methylation is not a marker of AMD.

Early and intermediate age-related macular degeneration: update and clinical review.

PubMed

García-Layana, Alfredo; Cabrera-López, Francisco; García-Arumí, José; Arias-Barquet, Lluís; Ruiz-Moreno, José M

2017-01-01

Age-related macular degeneration (AMD) is the leading cause of irreversible central vision loss in developed countries. With the aging of population, AMD will become globally an increasingly important and prevalent disease worldwide. It is a complex disease whose etiology is associated with both genetic and environmental risk factors. An extensive decline in the quality of life and progressive need of daily living assistance resulting from AMD among those most severely affected highlights the essential role of preventive strategies, particularly advising patients to quit smoking. In addition, maintaining a healthy diet, controlling other risk factors (such as hypertension, obesity, and atherosclerosis), and the use of nutritional supplements (antioxidants) are recommendable. Genetic testing may be especially important in patients with a family history of AMD. Recently, unifying criteria for the clinical classification of AMD, defining no apparent aging changes; normal aging changes; and early, intermediate, and late AMD stages, are of value in predicting AMD risk of progression and in establishing recommendations for the diagnosis, therapeutic approach, and follow-up of patients. The present review is focused on early and intermediate AMD and presents a description of the clinical characteristics and ophthalmological findings for these stages, together with algorithms for the diagnosis and management of patients, which are easily applicable in daily clinical practice.

Early and intermediate age-related macular degeneration: update and clinical review

PubMed Central

García-Layana, Alfredo; Cabrera-López, Francisco; García-Arumí, José; Arias-Barquet, Lluís; Ruiz-Moreno, José M

2017-01-01

Age-related macular degeneration (AMD) is the leading cause of irreversible central vision loss in developed countries. With the aging of population, AMD will become globally an increasingly important and prevalent disease worldwide. It is a complex disease whose etiology is associated with both genetic and environmental risk factors. An extensive decline in the quality of life and progressive need of daily living assistance resulting from AMD among those most severely affected highlights the essential role of preventive strategies, particularly advising patients to quit smoking. In addition, maintaining a healthy diet, controlling other risk factors (such as hypertension, obesity, and atherosclerosis), and the use of nutritional supplements (antioxidants) are recommendable. Genetic testing may be especially important in patients with a family history of AMD. Recently, unifying criteria for the clinical classification of AMD, defining no apparent aging changes; normal aging changes; and early, intermediate, and late AMD stages, are of value in predicting AMD risk of progression and in establishing recommendations for the diagnosis, therapeutic approach, and follow-up of patients. The present review is focused on early and intermediate AMD and presents a description of the clinical characteristics and ophthalmological findings for these stages, together with algorithms for the diagnosis and management of patients, which are easily applicable in daily clinical practice. PMID:29042759

Animal models of age related macular degeneration

PubMed Central

Pennesi, Mark E.; Neuringer, Martha; Courtney, Robert J.

2013-01-01

Age related macular degeneration (AMD) is the leading cause of vision loss of those over the age of 65 in the industrialized world. The prevalence and need to develop effective treatments for AMD has lead to the development of multiple animal models. AMD is a complex and heterogeneous disease that involves the interaction of both genetic and environmental factors with the unique anatomy of the human macula. Models in mice, rats, rabbits, pigs and non-human primates have recreated many of the histological features of AMD and provided much insight into the underlying pathological mechanisms of this disease. In spite of the large number of models developed, no one model yet recapitulates all of the features of human AMD. However, these models have helped reveal the roles of chronic oxidative damage, inflammation and immune dysregulation, and lipid metabolism in the development of AMD. Models for induced choroidal neovascularization have served as the backbone for testing new therapies. This article will review the diversity of animal models that exist for AMD as well as their strengths and limitations. PMID:22705444

Dry Age-Related Macular Degeneration Pharmacology

PubMed Central

Wright, Charles B.

2017-01-01

Age-related macular degeneration (AMD), the most common form of irreversible blindness in the industrially developed world, can present years before a patient begins to lose vision. For most of these patients, AMD never progresses past its early stages to the advanced forms that are principally responsible for the vast majority of vision loss. Advanced AMD can manifest as either an advanced avascular form known as geographic atrophy (GA) marked by regional retinal pigment epithelium (RPE) cell death or as an advanced form known as neovascular AMD marked by the intrusion of fragile new blood vessels into the normally avascular retina. Physicians have several therapeutic interventions available to combat neovascular AMD, but GA has no approved effective therapies as of yet. In this chapter, we will discuss the current strategies for limiting dry AMD in patients. We will also discuss previous attempts at pharmacological intervention that were tested in a clinical setting and consider reasons why these putative therapeutics did not perform successfully in large-scale trials. Despite the number of unsuccessful past trials, new pharmacological interventions may succeed. These future therapies may aid millions of AMD patients worldwide. PMID:27900609

Spectral induced polarization (SIP) response of mine tailings

NASA Astrophysics Data System (ADS)

Placencia-Gómez, Edmundo; Parviainen, Annika; Slater, Lee; Leveinen, Jussi

2015-02-01

Mine tailings impoundments are a source of leachates known as acid mine drainage (AMD) which can pose a contamination risk for surrounding surface and groundwater. Methodologies which can help management of this environmental issue are needed. We carried out a laboratory study of the spectral induced polarization (SIP) response of tailings from the Haveri Au-Cu mine, SW Finland. The primary objectives were, (1) to determine possible correlations between SIP parameters and textural properties associated with oxidative-weathering mechanisms, mineralogical composition and metallic content, and (2) to evaluate the effects of the pore water chemistry on SIP parameters associated with redox-inactive and redox-active electrolytes varying in molar concentration, conductivity and pH. The Haveri tailings exhibit well defined relaxation spectra between 100 and 10,000 Hz. The relaxation magnitudes are governed by the in-situ oxidative-weathering conditions on sulphide mineral surfaces contained in the tailings, and decrease with the oxidation degree. The oxidation-driven textural variation in the tailings results in changes to the frequency peak of the phase angle, the imaginary conductivity and chargeability, when plotted versus the pore water conductivity. In contrast, the real and the formation electrical conductivity components show a single linear dependence on the pore water conductivity. The increase of the pore water conductivity (dominated by the increase of ions concentration in solution) along with a transition to acidic conditions shifts the polarization peak towards higher frequencies. These findings show the unique sensitivity of the SIP method to potentially discriminate AMD discharges from reactive oxidation zones in tailings, suggesting a significant advantage for monitoring threatened aquifers.

Effect of acidity and elevated PCO2 on acid. Neutralization within pulsed limestone bed reactors receiving coal mine drainage

USGS Publications Warehouse

Watten, B.J.; Sibrell, P.L.; Schwartz, M.F.

2004-01-01

Limestone has potential for reducing reagent costs and sludge volume associated with the treatment of acid mine drainage (AMD), but its use has been restricted by slow dissolution rates and sensitivity to scale forming reactions that retard transport of H+ at the solid-liquid interface. We evaluated a pulsed limestone bed (PLB) remediation process designed to circumvent these problems through use of intermittently fluidized beds of granular limestone and elevated carbon dioxide pressure. PLB limestone dissolution (LD, mg/L), and effluent alkalinity (Alk, mg/L) were correlated with reactor pressure (PCO2, kPa), influent acidity (Acy, mg/L) and reactor bed height (H, cm) using a prototype capable of processing 10 L/min. The PLB process effectively neutralized sulfuric acid acidity over the range of 6-1033 mg/L (as CaCO3) while generating high concentrations of alkalinity (36-1086 mg/L) despite a hydraulic residence time of just 4.2-5.0 min. Alk and LD (mg/L CaCO3) rose with increases in influent acidity and PCO2 (p < 0.001) according to the models: Alk = 58 + 38.4 (PCO2)0.5 + 0.080 (Acy) - 0.0059(PCO2) 0.5 (Acy); LD = 55 + 38.3 (PCO2)0.5 + 1.08 (Acy) - 0.0059 (PCO2)0.5 (Acy). Alkalinity decreased at an increasing rate with reductions in H over the range of 27.3-77.5 cm (p < 0.001). Carbon dioxide requirements (Q(avg)CO2, L/min) increased with PCO2 (p < 0.001) following the model Q(avg)CO2 = 0.858 (PCO2)0.620, resulting in a greater degree of pH buffering (depression) within the reactors, a rise in limestone solubility and an increase in limestone dissolution related to carbonic acid attack. Corresponding elevated concentrations of effluent alkalinity allow for sidestream treatment with blending. Numerical modeling demonstrated that carbon dioxide requirements are reduced as influent acidity rises and when carbon dioxide is recovered from system effluent and recycled. Field trials demonstrated that the PLB process is capable of raising the pH of AMD above that required for hydrolysis and precipitation of Fe3+ and Al 3+ but not Fe2+ and Mn2+.

Observed and modeled seasonal trends in dissolved and particulate Cu, Fe, Mn, and Zn in a mining-impacted stream.

PubMed

Butler, Barbara A; Ranville, James F; Ross, Philippe E

2008-06-01

North Fork Clear Creek (NFCC) in Colorado, an acid-mine drainage (AMD) impacted stream, was chosen to examine the distribution of dissolved and particulate Cu, Fe, Mn, and Zn in the water column, with respect to seasonal hydrologic controls. NFCC is a high-gradient stream with discharge directly related to snowmelt and strong seasonal storms. Additionally, conditions in the stream cause rapid precipitation of large amounts of hydrous iron oxides (HFO) that sequester metals. Because AMD-impacted systems are complex, geochemical modeling may assist with predictions and/or confirmations of processes occurring in these environments. This research used Visual-MINTEQ to determine if field data collected over a two and one-half year study would be well represented by modeling with a currently existing model, while limiting the number of processes modeled and without modifications to the existing model's parameters. Observed distributions between dissolved and particulate phases in the water column varied greatly among the metals, with average dissolved fractions being >90% for Mn, approximately 75% for Zn, approximately 30% for Cu, and <10% for Fe. A strong seasonal trend was observed for the metals predominantly in the dissolved phase (Mn and Zn), with increasing concentrations during base-flow conditions and decreasing concentrations during spring-runoff. This trend was less obvious for Cu and Fe. Within hydrologic seasons, storm events significantly influenced in-stream metals concentrations. The most simplified modeling, using solely sorption to HFO, gave predicted percentage particulate Cu results for most samples to within a factor of two of the measured values, but modeling data were biased toward over-prediction. About one-half of the percentage particulate Zn data comparisons fell within a factor of two, with the remaining data being under-predicted. Slightly more complex modeling, which included dissolved organic carbon (DOC) as a solution phase ligand, significantly reduced the positive bias between observed and predicted percentage particulate Cu, while inclusion of hydrous manganese oxide (HMO) yielded model results more representative of the observed percentage particulate Zn. These results indicate that there is validity in the use of an existing model, without alteration and with typically collected water chemistry data, to describe complex natural systems, but that processes considered optimal for one metal might not be applicable for all metals in a given water sample.

Treated mine drainage effluent benefits Maryland and West Virginia fisherman

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ashby, J.C.

1995-12-31

In January of 1994, the Maryland Department of Natural Resources-Freshwater Fisheries Division and Mettiki Coal Corporation of Oakland, Maryland entered into a cooperative agreement to construct a trout rearing facility within Mettiki`s 10 million gallons per day acid mine drainage treatment system to supplement the DNR stockings in the newly revitalized North Branch of the Potomac River. Due to pyrite oxidation and a lack of alkaline buffering capacity in the Freeport coal strata, seven thousand gallons per minute of acidic water containing oxidized sulfide minerals must be pumped through Mettiki`s AMD treatment systems and elevated to Federal standards prior tomore » discharge into the Upper North Branch of the Potomac River. Utilizing hydrated lime, aeration, flocculation, sedimentation, and sludge recirculation, Mettiki`s treatment imparts superior trout propagation qualities to the discharge (pH of 8.1, dissolved oxygen of 8.0 ppm, temperature ranges of from 52 to 60 degrees Fahrenheit) and has allowed for weight gain throughout the typically dormant winter months. Presently, 30,000 brown, rainbow, and cutthroat trout are suspended in floating net pens within the systems` discharge collection pond where pH, flow, temperature, feed assimilation, and growth rates were compared with typical stream diversion hatcheries. Growth rates, lack of significant disease, and quality parameters coupled with ideal temperatures suggests treated acidic mine effluent can offer successful fish propagation opportunities.« less

Adsorptive removal of sulfate from acid mine drainage by polypyrrole modified activated carbons: Effects of polypyrrole deposition protocols and activated carbon source.

PubMed

Hong, Siqi; Cannon, Fred S; Hou, Pin; Byrne, Tim; Nieto-Delgado, Cesar

2017-10-01

Polypyrrole modified activated carbon was used to remove sulfate from acid mine drainage water. The polypyrrole modified activated carbon created positively charged functionality that offered elevated sorption capacity for sulfate. The effects of the activated carbon type, approach of polymerization, preparation temperature, solvent, and concentration of oxidant solution over the sulfate adsorption capacity were studied at an array of initial sulfate concentrations. A hardwood based activated carbon was the more favorable activated carbon template, and this offered better sulfate removal than when using bituminous based activated carbon or oak wood activated carbon as the template. The hardwood-based activated carbon modified with polypyrrole removed 44.7 mg/g sulfate, and this was five times higher than for the pristine hardwood-based activated carbon. Various protocols for depositing the polypyrrole onto the activated carbon were investigated. When ferric chloride was used as an oxidant, the deposition protocol that achieved the most N + atomic percent (3.35%) while also maintaining the least oxygen atomic percent (6.22%) offered the most favorable sulfate removal. For the rapid small scale column tests, when processing the AMD water, hardwood-based activated carbon modified with poly pyrrole exhibited 33 bed volume compared to the 5 bed volume of pristine activated carbons. Copyright © 2017 Elsevier Ltd. All rights reserved.

Optimization of limestone drains for long- term treatment of acidic mine drainage, Swatara Creek Basin, Schuylkill County, PA

USGS Publications Warehouse

Cravotta, Charles A.; Ward, S.J.; Koury, Daniel J.; Koch, R.D.

2004-01-01

Limestone drains were constructed in 1995, 1997, and 2000 to treat acidic mine drainage (AMD) from the Orchard, Buck Mtn., and Hegins discharges, respectively, in the Swatara Creek Basin, Southern Anthracite Coalfield, east-central Pennsylvania. This report summarizes the construction characteristics and performance of each of the limestone drains on the basis of influent and effluent quality and laboratory tests of variables affecting limestone dissolution rates. Data for influent and effluent indicate substantial alkalinity production by the Orchard and Buck Mtn. limestone drains and only marginal benefits from the Hegins drain. Nevertheless, the annual alkalinity loading rates have progressively declined with age of all three systems. Collapsible-container (cubitainer) testing was conducted to evaluate current scenarios and possible options for reconstruction and maintenance of the limestone drains to optimize their long-term performance. The cubitainer tests indicated dissolution rates for the current configurations that were in agreement with field flux data (net loading) for alkalinity and dissolved calcium. The dissolution rates in cubitainers were larger for closed conditions than open conditions, but the rates were comparable for coated and uncoated limestone for a given condition. Models developed on the basis of the cubitainer testing indicate (1) exponential declines in limestone mass and corresponding alkalinity loading rates with increased age of limestone drains and (2) potential for improved performance with enlargement, complete burial, and/or regular flushing of the systems.

Acute mental disorders and short and long term morbidity in patients with third degree flame burn: A population-based outcome study of 96,451 patients from the Nationwide Inpatient Sample (NIS) database (2001-2011).

PubMed

Mahendraraj, Krishnaraj; Durgan, Diane M; Chamberlain, Ronald S

2016-12-01

Although burn patients with preexisting mood disorders have been shown to have diminished clinical recovery, acute mental disorders (AMD) are often unrecognized despite a link with post-traumatic stress disorder and social maladjustment later on. This study assessed the clinical profile of a large cohort of burn patients who developed AMD compared to those with chronic mental illness (CMI) and those without mental health problems to assess the impact of AMI on burn outcomes. Admission data on 96,451 patients with third degree flame burns was abstracted from the Nationwide Inpatient Sample (NIS) Database from 2001 to 2011. AMD was defined as adjustment disorder (ICD-10 codes F43.2-F43.29) and acute stress disorder (F43.0), while CMI was defined as major depressive disorder (F33.0-F33.9) and bipolar disorder (F31.0-F31.9). Data was compared across three subgroups: AMD, CMI, and patients without any mood disorders. Categorical variables were compared using the Chi-square test, and continuous variables were compared using Student t-test and analysis of variance (ANOVA). Multivariate analysis using the "backward Wald" method was performed to calculate odds ratios (OR) and determine independent factors which increased the risk of developing AMD after burn. 979 (1%) burn patients were diagnosed with AMD, compared to 5971 (6.2%) with CMI and 89,501 (92.8%) without mood disorders at the time of the burn. Patients with AMD were significantly younger, predominantly male and Caucasian. Patients with AMD had a higher frequency of multiple third-degree burn sites. AMD patients had a significantly longer length of hospitalization and shorter actuarial survival. More AMD patients lacked social or family support, suffered from alcoholism or illicit drug abuse, and had a history of psychological trauma or self-inflicted injuries compared to other groups. After burn, 4.9% of AMD patients developed burn wound infections, 5.0% had nutritional deficiencies, 1.7% had skin graft failure, 0.7% had acute psychosis, and 3.7% had suicidal ideation, p<0.05. Multivariate analysis identified age 10-39 (OR 4.6), alcoholism (OR 1.4), drug abuse (OR 1.9), psychoses (OR 1.4), and total body surface are (TBSA) 10-39% third degree burns (OR 1.8) as independently associated with developing AMD, p<0.005. The development of AMD in burn patients is associated with poor clinical outcomes including longer hospitalization, decreased survival, and increased complication rates. Premorbid psychopathology, substance abuse and age were associated with a higher incidence AMD after burn than was the severity of the burn wound itself. Routine screening for psychological symptoms of AMD should be performed in all burn patients to avoid increased rates of short and long-term morbidity and mortality. Copyright © 2016 Elsevier Ltd and ISBI. All rights reserved.

Natural and anthropogenic atmospheric mercury in the European Arctic: a fractionation study

NASA Astrophysics Data System (ADS)

Steen, A. O.; Berg, T.; Dastoor, A. P.; Durnford, D. A.; Engelsen, O.; Hole, L. R.; Pfaffhuber, K. A.

2011-07-01

Gaseous elemental mercury (GEM) is converted to reactive gaseous mercury (RGM) during springtime Atmospheric Mercury Depletion Events (AMDE). This study reports the longest time series of GEM, RGM and particle-bound mercury (PHg) concentrations from a European Arctic site. From 27 April 2007 until 31 December 2008 composite GEM, RGM and PHg measurements were conducted in Ny-Ålesund (78° 54' N, 11° 53' E). The average concentrations of the complete dataset were 1.6 ± 0.3 ng m-3, 8 ± 13 pg m-3 and 8 ± 25 pg m-3 for GEM, RGM and PHg, respectively. For the complete dataset the atmospheric mercury distribution was 99 % GEM, whereas RGM and PHg constituted <1 %. The study revealed a seasonal distribution of GEM, RGM and PHg previously undiscovered in the Arctic. Increased concentrations of RGM were observed during the insolation period from March through August, while increased PHg concentrations occurred almost exclusively during the spring AMDE period in March and April. The elevated RGM concentrations suggest that atmospheric RGM deposition also occurs during the polar summer. RGM was suggested as the precursor for the PHg existence, but long range transportation of PHg has to be taken into consideration. Still there remain gaps in the knowledge of how RGM and PHg are related in the environment. RGM and PHg accounted for on average about 10 % of the depleted GEM during AMDEs. Although speculative, the fairly low RGM and PHg concentrations supported by the predominance of PHg with respect to RGM and no clear meteorological regime associated with these AMDEs would all suggest the events to be of non-local origin. With some exceptions, no clear meteorological regime was associated with the GEM, RGM and PHg concentrations throughout the year.

Complement activation and choriocapillaris loss in early AMD: Implications for pathophysiology and therapy

PubMed Central

Whitmore, S.Scott; Sohn, Elliott H.; Chirco, Kathleen R.; Drack, Arlene V.; Stone, Edwin M.; Tucker, Budd A.; Mullins, Robert F.

2015-01-01

Age-related macular degeneration (AMD) is a common and devastating disease that can result in severe visual dysfunction. Over the last decade, great progress has been made in identifying genetic variants that contribute to AMD, many of which lie in genes involved in the complement cascade. In this review we discuss the significance of complement activation in AMD, particularly with respect to the formation of the membrane attack complex in the aging choriocapillaris. We review the clinical, histological and biochemical data that indicate that vascular loss in the choroid occurs very early in the pathogenesis of AMD, and discuss the potential impact of vascular dropout on the retinal pigment epithelium, Bruch's membrane and the photoreceptor cells. Finally, we present a hypothesis for the pathogenesis of early AMD and consider the implications of this model on the development of new therapies. PMID:25486088

Complement activation and choriocapillaris loss in early AMD: implications for pathophysiology and therapy.

PubMed

Whitmore, S Scott; Sohn, Elliott H; Chirco, Kathleen R; Drack, Arlene V; Stone, Edwin M; Tucker, Budd A; Mullins, Robert F

2015-03-01

Age-related macular degeneration (AMD) is a common and devastating disease that can result in severe visual dysfunction. Over the last decade, great progress has been made in identifying genetic variants that contribute to AMD, many of which lie in genes involved in the complement cascade. In this review we discuss the significance of complement activation in AMD, particularly with respect to the formation of the membrane attack complex in the aging choriocapillaris. We review the clinical, histological and biochemical data that indicate that vascular loss in the choroid occurs very early in the pathogenesis of AMD, and discuss the potential impact of vascular dropout on the retinal pigment epithelium, Bruch's membrane and the photoreceptor cells. Finally, we present a hypothesis for the pathogenesis of early AMD and consider the implications of this model on the development of new therapies. Copyright © 2014 Elsevier Ltd. All rights reserved.

miRNAs as potential therapeutic targets for age-related macular degeneration.

PubMed

Wang, Shusheng; Koster, Kyle M; He, Yuguang; Zhou, Qinbo

2012-03-01

Since their recent discovery, miRNAs have been shown to play critical roles in a variety of pathophysiological processes. Such processes include pathological angiogenesis, the oxidative stress response, immune response and inflammation, all of which have been shown to have important and interdependent roles in the pathogenesis and progression of age-related macular degeneration (AMD). Here we present a brief review of the pathological processes involved in AMD and review miRNAs and other noncoding RNAs involved in regulating these processes. Specifically, we discuss several candidate miRNAs that show promise as AMD therapeutic targets due to their direct involvement in choroidal neovascularization or retinal pigment epithelium atrophy. We discuss potential miRNA-based therapeutics and delivery methods for AMD and provide future directions for the field of miRNA research with respect to AMD. We believe the future of miRNAs in AMD therapy is promising.

Age-related macular degeneration: current treatments

PubMed Central

Hubschman, Jean Pierre; Reddy, Shantan; Schwartz, Steven D

2009-01-01

Purpose: Although important progress has been made in understanding age-related macular degeneration (AMD), management of the disease continues to be a challenge. AMD research has led to a widening of available treatment options and improved prognostic perspectives. This essay reviews these treatment options. Design: Interpretative essay. Methods: Literature review and interpretation. Results: Current treatments to preserve vision in patients with non-exudative AMD include antioxidant vitamins and mineral supplementations. Exudative AMD is currently most often treated monthly with anti-VEGF intravitreal injections. However, investigators are beginning to experiment with combination therapy and surgical approaches in an attempt to limit the number of treatment and reduce the financial burden on the health care system. Conclusion: By better understanding the basis and pathogenesis of AMD, newer therapies will continue to be developed that target specific pathways in patients with AMD, with the hoped for outcome of better management of the disease and improved visual acuity. PMID:19668560

The Role of mf-ERG in the Diagnosis and Treatment of Age-Related Macular Degeneration: Electrophysiological Features of AMD.

PubMed

Moschos, Marilita M; Nitoda, Eirini

2018-01-01

Age-related macular cegeneration (AMD) is the leading cause of visual dysfunction worldwide, affecting 9-25% of individuals between 65 and 75 years old. We have reviewed the published articles investigating the role of multifocal electroretinogram (mf-ERG) in the diagnosis and treatment of AMD. Visual evoked potentials have revealed decreased amplitudes and higher latencies in patients with AMD, while the degeneration of photoreceptors and abnormalities of retinal pigment epithelium can be identified by electro-oculogram recordings. Moreover, ERG can detect the functional abnormalities observed in AMD and evaluate each therapeutic approach. The record of local electrophysiological responses coming from different retinal areas can be accurately performed by mfERG. The accuracy of mfERG in detecting the degeneration of photoreceptors, as well the disturbances of macular function, could be useful both in the early diagnosis of AMD and the assessment of treatment efficacy.

Adaptation Options for Land Drainage Systems Towards Sustainable Agriculture and Environment: A Czech Perspective

NASA Astrophysics Data System (ADS)

Kulhavý, Zbyněk; Fučík, Petr

2015-04-01

In this paper, issues of agricultural drainage systems are introduced and discussed from the views of their former, current and future roles and functioning in the Czech Republic (CR). A methodologically disparate survey was done on thirty-nine model localities in CR with different intensity and state of land drainage systems, aimed at description of commonly occurred problems and possible adaptations of agricultural drainage as perceived by farmers, land owners, landscape managers or by protective water management. The survey was focused on technical state of drainage, fragmentation of land ownership within drained areas as well as on possible conflicts between agricultural and environmental interests in a landscape. Achieved results confirmed that there is obviously an increasing need to reassess some functions of prevailingly single-purpose agricultural drainage systems. Drainage intensity and detected unfavourable technical state of drainage systems as well as the risks connected with the anticipated climate change from the view of possible water scarcity claims for a complex solution. An array of adaptation options for agricultural drainage systems is presented, aiming at enhancement of water retention time and improvement of water quality. It encompasses additional flow-controlling measures on tiles or ditches, or facilities for making selected parts of a drainage system inoperable in order to retain or slow down the drainage runoff, to establish water accumulation zones and to enhance water self-cleaning processes. However, it was revealed that the question of landowner parcels fragmentation on drained land in CR would dramatically complicate design and realization of these measures. Presented solutions and findings are propounded with a respect to contemporary and future state policies and international strategies for sustainable agriculture, water management and environment.

Environmental cadmium and lead exposures and age-related macular degeneration in U.S. adults: The National Health and Nutrition Examination Survey 2005 to 2008

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Erin W.; Schaumberg, Debra A.; Center for Translational Medicine, Department of Ophthalmology and Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT

Age-related macular degeneration (AMD) is a complex disease resulting from the interplay of genetic predisposition and environmental exposures, and has been linked to oxidative stress and inflammatory mechanisms. Lead and cadmium can accumulate in human retinal tissues and may damage the retina through oxidative stress, and may thereby play a role in the development of AMD. We examined associations between blood lead, blood cadmium, and urinary cadmium concentrations and the presence of AMD in 5390 participants aged 40 years and older with blood lead and blood cadmium measures and a subsample of 1548 with urinary cadmium measures in the 2005–2008more » National Health and Nutrition Examination Surveys. AMD was identified by grading retinal photographs with a modification of the Wisconsin Age-Related Maculopathy Grading System. The weighted prevalence of AMD was 6.6% (n=426). Controlling for age, gender, race/ethnicity, education and body mass index, adults in the highest blood cadmium quartile had higher odds of AMD compared to the lowest quartile (odds ratio [OR], 1.56; 95% CI, 1.02–2.40), with a significant trend across quartiles (p-trend=0.02). After further adjustment for pack-years of cigarette smoking, estimates were somewhat attenuated (OR, 1.43; 95% CI, 0.91–2.27; p-trend=0.08). Similar associations were found with urinary cadmium. The association between urinary cadmium and AMD was stronger in non-Hispanic whites (NHW) than in non-Hispanic blacks (NHB) (OR, 3.31; 95% CI, 1.37–8.01 for levels above versus below the median among NHW; OR,1.45; 95% CI, 0.40–5.32 for levels above versus below the median among NHB; p-interaction=0.03). We found no association between blood lead levels and AMD. Higher cadmium body burden may increase risk of AMD, particularly among non-Hispanic white individuals; however, additional studies are needed before firm conclusions can be drawn. - Highlights: • We examined the association of cadmium and lead with age-related macular degeneration (AMD) in U.S. adults. • Cadmium in both blood and urine was borderline significantly associated with the risk of AMD. • Blood lead was not associated with the risk of AMD. • The association between urine cadmium and AMD was stronger in whites than in blacks.« less

Incidence of Age-Related Macular Degeneration in a Multi-Ethnic United States Population: The Multi-Ethnic Study of Atherosclerosis.

PubMed

Fisher, Diana E; Klein, Barbara E K; Wong, Tien Y; Rotter, Jerome I; Li, Xiaohui; Shrager, Sandi; Burke, Gregory L; Klein, Ronald; Cotch, Mary Frances

2016-06-01

To describe the incidence of age-related macular degeneration (AMD) and associated risk factors in 4 racial/ethnic groups (white, black, Hispanic, and Chinese) residing in the United States. Prospective cohort study. A total of 3811 participants, aged 46 to 86 years, from the Multi-Ethnic Study of Atherosclerosis (MESA) cohort, with retinal data collected twice, on average, 8 years apart. Fundus images, taken using a digital camera through dark-adapted pupils using a standard protocol and the same equipment at both study visits, were graded centrally for early and late AMD on the basis of drusen size, type and area, increased retinal pigment, retinal pigment epithelial depigmentation, neovascular lesions, and geographic atrophy using the modified Wisconsin Age-Related Maculopathy Grading System. Demographic, clinical, and laboratory measures were included in multivariable regression models to determine their impact on the variation in AMD incidence among racial/ethnic groups. Incident early and late AMD. The overall 8-year age- and sex-standardized incidence of early and late AMD were 4.1% and 2.3%, respectively, with incidence of early and late AMD highest in whites (5.3% and 4.1%, respectively), intermediate in Chinese (4.5% and 2.2%, respectively) and Hispanics (3.3% and 0.8%, respectively), and lowest in blacks (1.6% and 0.4%, respectively). By adjusting for age and sex, blacks had a 70% lower risk of developing early AMD than whites, and this decreased only slightly to a 67% lower risk after multivariable adjustment. By adjusting for age, sex, and race/ethnicity, hyperopia was associated with early AMD (odds ratio [OR], 1.51; 95% confidence interval [CI], 1.04-2.20), as was astigmatism (OR, 1.47; 95% CI, 1.00-2.16), but not myopia (P = 0.29). Age, race/ethnicity, current smoking, hyperopia, and AMD-susceptibility genotypes Complement Factor H (CFH) RS1061170 and Age Related Maculopathy Susceptibility 2 (ARMS2) RS3793917 were independently associated with incident early AMD in multivariable models for the combined sample. However, the only statistically significant factor consistently associated with incident early AMD across the 4 racial/ethnic groups was increasing age. Risk factors for late AMD were not assessed because of its low incidence, particularly across racial/ethnic groups. Variation in the incidence of early AMD exists among racial/ethnic groups in the United States and is not explained by the clinical, genetic, and environmental factors included in this study. Published by Elsevier Inc.

Absolute and estimated values of macular pigment optical density in young and aged Asian participants with or without age-related macular degeneration.

PubMed

Ozawa, Yoko; Shigeno, Yuta; Nagai, Norihiro; Suzuki, Misa; Kurihara, Toshihide; Minami, Sakiko; Hirano, Eri; Shinoda, Hajime; Kobayashi, Saori; Tsubota, Kazuo

2017-08-29

Lutein and zeaxanthin are suggested micronutrient supplements to prevent the progression of age-related macular degeneration (AMD), a leading cause of blindness worldwide. To monitor the levels of lutein/zeaxanthin in the macula, macular pigment optical density (MPOD) is measured. A commercially available device (MPSII®, Elektron Technology, Switzerland), using technology based on heterochromatic flicker photometry, can measure both absolute and estimated values of MPOD. However, whether the estimated value is applicable to Asian individuals and/or AMD patients remains to be determined. The absolute and estimated values of MPOD were measured using the MPSII® device in 77 participants with a best-corrected visual acuity (BCVA) > 0.099 (logMAR score). The studied eyes included 17 young (20-29 years) healthy, 26 aged (>50 years) healthy, 18 aged and AMD-fellow, and 16 aged AMD eyes. The mean BCVA among the groups were not significantly different. Both absolute and estimated values were measurable in all eyes of young healthy group. However, absolute values were measurable in only 57.7%, 66.7%, and 43.8%, of the aged healthy, AMD-fellow, and AMD groups, respectively, and 56.7% of the eyes included in the 3 aged groups. In contrast, the estimated value was measurable in 84.6%, 88.9% and 93.8% of the groups, respectively, and 88.3% of eyes in the pooled aged group. The estimated value was correlated with absolute value in individuals from all groups by Spearman's correlation coefficient analyses (young healthy: R 2  = 0.885, P = 0.0001; aged healthy: R 2  = 0.765, P = 0.001; AMD-fellow: R 2  = 0.851, P = 0.0001; and AMD: R 2  = 0.860, P = 0.013). Using the estimated value, significantly lower MPOD values were found in aged AMD-related eyes, which included both AMD-fellow and AMD eyes, compared with aged healthy eyes by Student's t-test (P = 0.02). Absolute, in contrast to estimated, value was measurable in a limited number of aged participants; however, it was correlated with estimated value both in young and aged Asian populations with or without AMD. These results may inform future clinical studies investigating the measurement of MPOD in understanding the role of macular pigments in the pathogenesis of AMD.

Peripheral blood mononuclear cells from neovascular age-related macular degeneration patients produce higher levels of chemokines CCL2 (MCP-1) and CXCL8 (IL-8).

PubMed

Lechner, Judith; Chen, Mei; Hogg, Ruth E; Toth, Levente; Silvestri, Giuliana; Chakravarthy, Usha; Xu, Heping

2017-02-23

Infiltrating immune cells including monocytes/macrophages have been implicated in the pathogenesis of neovascular age-related macular degeneration (nAMD). The aim of this study was to investigate the cytokine and chemokine expression and secretion profile of peripheral blood mononuclear cells (PBMCs) from nAMD patients and the relationship between the cytokine/chemokine expression profile and clinical phenotype of nAMD, including macular fibrosis, macular atrophy or the responsiveness to anti-VEGF therapy. One hundred sixty-one nAMD patients and 43 controls were enrolled in this study. nAMD patients were divided into subgroups based on the presence/absence of (1) macular atrophy, (2) macular fibrosis and (3) responsiveness to anti-VEGF therapy; 25-30 ml of peripheral blood were obtained from all participants and 5 ml were used for serum collection, and the remaining were used for PBMC isolation using density gradient centrifugation. Intracellular cytokine expressions by PBMCs following phorbol 12-myristate 13-acetate (PMA) and ionomycin stimulation were examined using flow cytometry. Cytokine productions in lipopolysaccharides (LPS)-or 1% oxygen -treated PBMC were measured using cytometric bead array (CBA) assay. In addition, cytokine and chemokine levels in the serum were also measured by CBA assay. PBMCs from nAMD patients secreted higher levels of IL-8, CCL2 and VEGF, especially following LPS and 1% oxygen stimulation, than those from controls. 60~80% of IL-8 producing cells were CD11b + CD3 - monocytes. The percentage of CD11b + CD3 - IL-8 + was significantly increased in nAMD patients compared to controls. PBMCs from nAMD patients without macular fibrosis produced the highest levels of IL-8 and CCL2, whilst PBMCs from nAMD patients with macular atrophy produced highest levels of VEGF. In addition, PBMCs from patients who partially responded to anti-VEGF produced higher levels of IL-8 compared to the cells from complete responders. Interestingly, serum level of CCL2 was not increased in nAMD patients although there was a trend of increased IL-8 in nAMD patients. PBMCs, in particular monocytes, may contribute to CNV development in nAMD through secreting elevated levels of IL-8, CCL2 and VEGF after they are recruited to the macula. Apart from VEGF, IL-8 and CCL2 may be additional targets for nAMD management.

Oxidative stress, innate immunity, and age-related macular degeneration

PubMed Central

Shaw, Peter X.; Stiles, Travis; Douglas, Christopher; Ho, Daisy; Fan, Wei; Du, Hongjun; Xiao, Xu

2016-01-01

Age-related macular degeneration (AMD) is a leading cause of vision loss affecting tens of millions of elderly worldwide. Early AMD is characterized by the appearance of soft drusen, as well as pigmentary changes in the retinal pigment epithelium (RPE). These soft, confluent drusen can progress into two forms of advanced AMD: geographic atrophy (GA, or dry AMD) or choroidal neovascularization (CNV, or wet AMD). Both forms of AMD result in a similar clinical progression in terms of loss of central vision. The exact mechanism for developing early AMD, as well as triggers responsible for progressing to advanced stage of disease, is still largely unknown. However, significant evidence exists demonstrating a complex interplay of genetic and environmental factors as causes of AMD progression. Multiple genes and/or single nucleotide polymorphisms (SNPs) have been found associated with AMD, including various genes involved in the complement pathway, lipid metabolism and extracellular matrix (ECM) remodeling. Of the known genetic contributors to disease risk, the CFH Y402H and HTRA1/ARMS polymorphisms contribute to more than 50% of the genetic risk for AMD. Environmentally, oxidative stress plays a critical role in many aging diseases including cardiovascular disease, cancer, Alzheimer’s disease and AMD. Due to the exposure to sunlight and high oxygen concentration, the oxidative stress burden is higher in the eye than other tissues, which can be further complicated by additional oxidative stressors such as smoking. Increasingly, evidence is accumulating suggesting that functional abnormalities of the innate immune system incurred via high risk genotypes may be contributing to the pathogenesis of AMD by altering the inflammatory homeostasis in the eye, specifically in the handling of oxidation products. As the eye in non-pathological instances maintains a low level of inflammation despite the presence of a relative abundance of potentially inflammatory molecules, we have previously hypothesized that the tight homeostatic control of inflammation via the innate immune system is likely critical for avoidance of disease progression. However, the presence of a multitude of potential triggers of inflammation results in a sensitive balance in which perturbations thereof would subsequently alter the inflammatory state of the retina, leading to a state of chronic inflammation and pathologic progression. In this review, we will highlight the background literature surrounding the known genetic and environmental contributors to AMD risk, as well as a discussion of the potential mechanistic interplay of these factors that lead to disease pathogenesis with particular emphasis on the delicate control of inflammatory homeostasis and the centrality of the innate immune system in this process. PMID:27239555

[Macular choroidal blood flow in concurrent age-related macular degeneration and primary open-angle glaucoma].

PubMed

Panova, I E; Ermak, E M; Shaimova, T A; Shaimova, V A

2016-01-01

Ocular circulation disorders are an important factor in the development of primary open-angle glaucoma (POAG) and age-related macular degeneration (AMD). To date, however, there have been no studies on choroidal blood flow peculiarities in case of concurrent AMD and POAG. to determine distinctive features of choroidal blood flow characteristic of concurrent AMD and POAG and to assess their role in disease pathogenesis. Macular choroidal blood flow, including blood supply, was assessed in 54 patients (102 eyes) by means of Doppler ultrasound. Three groups were formed: group 1 - 38 eyes with both AMD and POAG; group 2 - 41 eyes with AMD and no signs of optic nerve pathology; and group 3 - 23 eyes with POAG and no signs of AMD. Groups 1 and 2 were subdivided into two subgroups each: А - atrophic AMD and B - macular drusen. The mean patient age was 78.7±8.4 years. The following parameters of choroidal blood flow were of interest: peak systolic velocity (Vps), end diastolic velocity (Ved), time-averaged maximum velocity (Vtamax), and resistance index (RI). Groups 1, 3, and 2A had an evident choroidal hypoperfusion in the macular area (decreased Vtamax) with uncompensated perfusion deficit, despite autoregulation efforts (decreased Vps, Ved, decreased or normal RI). Group 2B demonstrated a significantly higher rate of choroidal hyperperfusion (increased Vps, Ved, Vtamax, and RI). Concurrent AMD and POAG are notable for choroidal hypoperfusion in the macular area that leads to inadequate trophism of the neurosensory retina and can aggravate the course of AMD contributing to progression of its atrophic form.

Age-related macular degeneration: the importance of family history as a risk factor.

PubMed

Shahid, Humma; Khan, Jane C; Cipriani, Valentina; Sepp, Tiina; Matharu, Baljinder K; Bunce, Catey; Harding, Simon P; Clayton, David G; Moore, Anthony T; Yates, John R W

2012-03-01

Family history is considered a risk factor for age-related macular degeneration (AMD). With the advent of effective therapy for the disease, the importance of family history merits further investigation. This study quantifies the risk associated with family history, first, by a case-control study of reported family history and, second, by examining the siblings of AMD cases. The authors recruited cases with advanced AMD, spouses and siblings. All subjects were carefully phenotyped. Clinical findings in the siblings were compared with spouses. Information about family history was collected. The ORs for reported family history of AMD were calculated. Analyses were adjusted for age, smoking and genotype. 495 AMD cases, 259 spouses and 171 siblings were recruited. The OR for AMD was 27.8 (CI 3.8 to 203.0; p=0.001) with a reported family history of an affected parent and 12.0 (CI 3.7 to 38.6; p<0.0001) with a history of an affected sibling. ORs adjusted for age and smoking were higher. Examination of siblings confirmed their increased risk with 23% affected by AMD and an OR of 10.8 (4.5 to 25.8; p<0.0001). Adjusting for age increased the OR to 16.1 (6.2 to 41.8). The risk of AMD is greatly increased by having an affected first-degree relative. Those at risk need to be made aware of this and AMD patients should advise siblings and children to seek prompt ophthalmological advice if they develop visual symptoms of distortion or reduced vision.

Complement Factor D in Age-Related Macular Degeneration

PubMed Central

Stanton, Chloe M.; Yates, John R.W.; den Hollander, Anneke I.; Seddon, Johanna M.; Swaroop, Anand; Stambolian, Dwight; Fauser, Sascha; Hoyng, Carel; Yu, Yi; Atsuhiro, Kanda; Branham, Kari; Othman, Mohammad; Chen, Wei; Kortvely, Elod; Chalmers, Kevin; Hayward, Caroline; Moore, Anthony T.; Dhillon, Baljean; Ueffing, Marius

2011-01-01

Purpose. To examine the role of complement factor D (CFD) in age-related macular degeneration (AMD) by analysis of genetic association, copy number variation, and plasma CFD concentrations. Methods. Single nucleotide polymorphisms (SNPs) in the CFD gene were genotyped and the results analyzed by binary logistic regression. CFD gene copy number was analyzed by gene copy number assay. Plasma CFD was measured by an enzyme-linked immunosorbent assay. Results. Genetic association was found between CFD gene SNP rs3826945 and AMD (odds ratio 1.44; P = 0.028) in a small discovery case-control series (462 cases and 325 controls) and replicated in a combined cohorts meta-analysis of 4765 cases and 2693 controls, with an odds ratio of 1.11 (P = 0.032), with the association almost confined to females. Copy number variation in the CFD gene was identified in 13 out of 640 samples examined but there was no difference in frequency between AMD cases (1.3%) and controls (2.7%). Plasma CFD concentration was measured in 751 AMD cases and 474 controls and found to be elevated in AMD cases (P = 0.00025). The odds ratio for those in the highest versus lowest quartile for plasma CFD was 1.81. The difference in plasma CFD was again almost confined to females. Conclusions. CFD regulates activation of the alternative complement pathway, which is implicated in AMD pathogenesis. The authors found evidence for genetic association between a CFD gene SNP and AMD and a significant increase in plasma CFD concentration in AMD cases compared with controls, consistent with a role for CFD in AMD pathogenesis. PMID:22003108

Dactinomycin and Vincristine Toxicity in the Treatment of Childhood Cancer: A Retrospective Study from the Children’s Oncology Group

PubMed Central

Langholz, Bryan; Skolnik, Jeffrey M.; Barrett, Jeffrey S.; Renbarger, Jamie; Seibel, Nita L.; Zajicek, Anne; Arndt, Carola A.S.

2011-01-01

Background Dactinomycin (AMD) and vincristine (VCR) have been used for the treatment of childhood cancer over the past 40 years but evidence-based dosing guidance is lacking. Methods Patient AMD and VCR dose and drug-related adverse event (AE) information from four rhabdomyosarcoma (RMS) and two Wilms tumor (WT) studies were assembled. Statistical modeling was used to account for differences in AE data collection across studies, develop rate models for grade 3/4 CTCAE v3 hepatic- (AMD) and neuro- (AMD) toxicity, assess variation in toxicity rates over age and other factors, and predict toxicity risk under current dosing guidelines. Results For the same dose/body size, AMD toxicity rates were higher in patients <1 year than older patients and VCR toxicity rates increased with age. The statistical model provided estimates for AMD and VCR toxicity risk under current dosing schedules and indicated that patients of smaller body size were at lower risk of VCR toxicity than larger patients of the same age. The rate of AMD toxicity was highest early in treatment and was lower in patients who tolerated initial AMD without toxicity. Conclusion The observed decrease in AMD toxicity rate with cumulative dose may indicate sensitivity in a subgroup of patients while the observed increase in VCR toxicity risk with age may indicate changing sensitivity to VCR. Current dosing practices result in a fairly uniform toxicity profile within age group. However, PK/PD studies should be done to provide further provide further information on best dosing guidelines. PMID:21671362

The association of aspirin use with age-related macular degeneration.

PubMed

Liew, Gerald; Mitchell, Paul; Wong, Tien Yin; Rochtchina, Elena; Wang, Jie Jin

2013-02-25

To determine whether regular aspirin use is associated with a higher risk for developing age-related macular degeneration (AMD) by using analyzed data from a 15-year prospective cohort. A prospective analysis was conducted of data from an Australian population-based cohort with 4 examinations during a 15-year period (1992-1994 to 2007-2009). Participants completed a detailed questionnaire at baseline assessing aspirin use, cardiovascular disease status, and AMD risk factors. Age-related macular degeneration was graded side-by-side from retinal photographs taken at each study visit to assess the incidence of neovascular (wet) AMD and geographic atrophy (dry AMD) according to the international AMD classification. Of 2389 baseline participants with follow-up data available, 257 individuals (10.8%) were regular aspirin users and 63 of the 2389 developed neovascular AMD. Persons who were regular aspirin users were more likely to have incident neovascular AMD: the 15-year cumulative incidence was 9.3% in users and 3.7% in nonusers. After adjustment for age, sex, smoking, history of cardiovascular disease, systolic blood pressure, and body mass index, persons who were regular aspirin users had a higher risk of developing neovascular AMD (odds ratio [OR], 2.46; 95% CI, 1.25-4.83). The association showed a dose-response effect (multivariate-adjusted P = .01 for trend). Aspirin use was not associated with the incidence of geographic atrophy (multivariate-adjusted OR, 0.99; 95% CI, 0.59-1.65). Regular aspirin use is associated with increased risk of incident neovascular AMD, independent of a history of cardiovascular disease and smoking.

[⁹⁹mTc]O₂-AMD3100 as a SPECT tracer for CXCR4 receptor imaging.

PubMed

Hartimath, Siddesh V; Domanska, Urszula M; Walenkamp, Annemiek M E; Rudi A J O, Dierckx; de Vries, Erik F J

2013-05-01

CXCR4 plays an important role in HIV infection, tumor progression, neurogenesis, and inflammation. In-vivo imaging of CXCR4 could provide more insight in the role of this receptor in health and disease. The aim of this study was to investigate [(99m)Tc]O₂-AMD3100 as a potential SPECT tracer for imaging of CXCR4. AMD3100 was labelled with [(99m)Tc]pertechnetate. A cysteine challenge assay was performed to test the tracer stability. Heterologous and homologous receptor binding assay and internalization assay were performed in CXCR4 expressing Jurkat-T cells. Ex vivo biodistribution was studied in healthy mice at 30, 60, and 120 min after tracer injection. Tumor uptake of the tracer was determined by microSPECT imaging in nude mice xenografted with human PC-3 prostate tumor. Specificity of tracer uptake was determined by blocking studies using an excess of unlabelled AMD3100. AMD3100 was labelled with technetium-99m with a radiochemical yield of >98%. The tracer was stable in PBS and mouse plasma for at least 6h at 37 °C. Heterologous and homologous binding assays with AMD3100 showed IC50 values of 240 ± 10 μM, and 92 ± 5 μM for [(125)I]SDF-1α and [(99m)Tc]O₂-AMD3100 respectively, with negligible receptor internalisation. The tracer showed high uptake in liver, lungs, spleen, thymus, intestine and bone. Blocking dose of AMD3100.8HCl (20mg/kg) decreased the uptake in these organs (p<0.05). [(99m)Tc]O2-AMD3100 showed specific tumor accumulation in mice bearing PC-3 xenografts model. Time activity curves (TAC) in AMD3100 pre-treated animals tracer showed 1.7 times less tumor uptake as compared to control animals (p<0.05). [(99m)Tc]O2-AMD3100 is readily labelled, is stable in plasma and displays a favourable binding affinity for the CXCR4 receptors. [(99m)Tc O₂-AMD3100 shows specific binding in organs with high CXCR4 expression and in CXCR4 positive tumors. These results justify further evaluation of this radiopharmaceutical as a potential biomarker for the non-invasive imaging of CXCR4 receptors. Copyright © 2013 Elsevier Inc. All rights reserved.

Whole-Exome Sequencing in Age-Related Macular Degeneration Identifies Rare Variants in COL8A1, a Component of Bruch's Membrane.

PubMed

Corominas, Jordi; Colijn, Johanna M; Geerlings, Maartje J; Pauper, Marc; Bakker, Bjorn; Amin, Najaf; Lores Motta, Laura; Kersten, Eveline; Garanto, Alejandro; Verlouw, Joost A M; van Rooij, Jeroen G J; Kraaij, Robert; de Jong, Paulus T V M; Hofman, Albert; Vingerling, Johannes R; Schick, Tina; Fauser, Sascha; de Jong, Eiko K; van Duijn, Cornelia M; Hoyng, Carel B; Klaver, Caroline C W; den Hollander, Anneke I

2018-04-26

Genome-wide association studies and targeted sequencing studies of candidate genes have identified common and rare variants that are associated with age-related macular degeneration (AMD). Whole-exome sequencing (WES) studies allow a more comprehensive analysis of rare coding variants across all genes of the genome and will contribute to a better understanding of the underlying disease mechanisms. To date, the number of WES studies in AMD case-control cohorts remains scarce and sample sizes are limited. To scrutinize the role of rare protein-altering variants in AMD cause, we performed the largest WES study in AMD to date in a large European cohort consisting of 1125 AMD patients and 1361 control participants. Genome-wide case-control association study of WES data. One thousand one hundred twenty-five AMD patients and 1361 control participants. A single variant association test of WES data was performed to detect variants that are associated individually with AMD. The cumulative effect of multiple rare variants with 1 gene was analyzed using a gene-based CMC burden test. Immunohistochemistry was performed to determine the localization of the Col8a1 protein in mouse eyes. Genetic variants associated with AMD. We detected significantly more rare protein-altering variants in the COL8A1 gene in patients (22/2250 alleles [1.0%]) than in control participants (11/2722 alleles [0.4%]; P = 7.07×10 -5 ). The association of rare variants in the COL8A1 gene is independent of the common intergenic variant (rs140647181) near the COL8A1 gene previously associated with AMD. We demonstrated that the Col8a1 protein localizes at Bruch's membrane. This study supported a role for protein-altering variants in the COL8A1 gene in AMD pathogenesis. We demonstrated the presence of Col8a1 in Bruch's membrane, further supporting the role of COL8A1 variants in AMD pathogenesis. Protein-altering variants in COL8A1 may alter the integrity of Bruch's membrane, contributing to the accumulation of drusen and the development of AMD. Copyright © 2018 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.