Geochemical shifts, ecological consequences, and onset of meromixis in a mine water impacted boreal lake

Sediment chemistry and arcellacean community composition were analyzed to study the ecological effects of copper mine-derived acidic and metal-rich waters in a freshwater bay in eastern Finland. To track spatial and temporal changes in the bay, 32 mine-impacted (top) and pre-impact (bottom) samples were analyzed from 16 short sediment cores taken along a transect extending from the pollution source. In addition, short cores from the impacted and reference sites were studied. Recent sediments displayed a geochemical gradient from the inner bay, where mine water is discharged, to the outer bay. Inner bay sites were enriched with C, S, and Fe, whereas Mn was depleted, but has precipitated in the outer bay. Among the heavy metals, Cu, Al, Zn, and Ni concentrations had increased in the inner and mid bay, while Co and Cd concentrations had increased at mid-bay sites. The change from the natural to mine-impacted condition was also seen in faunal gradients. According to ordination and distance measures, the greatest changes in species composition occurred in the inner bay, with fairly small changes in the outer bay. Numerical methods suggested that metals (Cu, Pb, Al, Zn, Cr), redox-sensitive elements (Fe, Mn), organic carbon and nutrients could be related to changes in arcellacean assemblages. Geochemical changes in the impacted core started at ~20 cm with increases in S alternating with peaks in Cr and Mg. Heavy metal concentrations increased markedly at 10 cm, after the active mining period, suggesting the beginning of acid mine drainage. Geochemical changes at ~20 cm were already apparent in the arcellacean assemblages, but the most notable change coincided with the geochemical shift at 10 cm, with signs of decreased pH. Numerical methods suggest that mining-related metals Co, Cu, Zn and Ni co-vary with arcellaceans, but Al appears to behave independently with respect to the species data.

Microbiological monitoring of acid mine drainage treatment systems and aquatic surroundings using real-time PCR

The introduction of nitrogen from coal into the surface watershed nitrogen cycle due to coal mining activity

Only little attention has been paid to the impact of acid mine drainages (AMD) on aquatic ecosystems in Central Europe. In this study, we investigate the physico-chemical properties of low-order streams and the response of benthic invertebrates to AMD pollution in the Banská Štiavnica mining region (Slovakia). The studied streams showed typical signs of mine drainage pollution: higher conductivity, elevated iron, aluminum, zinc and copper loads and accumulations of ferric precipitates. Electric conductivity correlated strongly with most of the investigated elements (weighted mean absolute correlation = 0.95) and, therefore, can be recommended as a good proxy indicator for rapid AMD pollution assessments. The diversity and composition of invertebrate assemblages was related to water chemistry. Taxa richness decreased significantly along an AMD-intensity gradient. While moderately affected sites supported relatively rich assemblages, the harshest environmental conditions (pH < 2.5) were typical for the presence of a limited number of very tolerant taxa, such as Oligochaeta and some Diptera (Limnophyes, Forcipomyiinae). The trophic guild structure correlated significantly with AMD chemistry, whereby predators completely disappeared under the most severe AMD conditions. We also provide a brief review of the AMD literature and outline the needs for future detailed studies involving functional descriptors of the impact of AMD on aquatic ecosystems.

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 × 107Nitrospira 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.

Acid Mine Drainage (AMD) treatment systems can be broadly categorised as either active or passive systems, which differ according to their ability to handle Acidity, flow rate and Acidity Load of the influent AMD. Most passive and active systems utilise aggregate carbonate to neutralise the pH and encourage precipitation of metals as hydroxides or sulphide minerals. In addition, passive treatment systems often use organic matter to provide alkalinity and create reducing conditions which favour the precipitation of metal sulphides.Active treatment systems can be engineered to accommodate essentially any acidity, flow rate and acidity load. Active treatment of AMD can be achieved using fixed plants or portable equipment for in-situ treatment. Passive treatment systems are almost invariably used for post closure treatment scenarios, and are best suited to AMD with low Acidity and low flow rates. The key factors in selection and design of active and passive AMD treatment systems are water chemistry including pH, metals, sulphate levels and redox state and flow rate of influent AMD, and the objectives of AMD treatment. Other important factors include capital and operating costs, availability of suitable treatment reagents or materials and sludge management issues. Keywords: Acid Mine Drainage, Active Treatment, Passive Treatment, Coal Mining.

Reference diatom assemblage response to restoration of an acid mine drainage stream

ABSTRACTThe research investigates a novel method to treat acid mine drainage (AMD) using lime and sodium hydroxide modified fly ash (NCFA) with varied dose and time. The analysis showed that pH was raised to 8.24 and approximately 99% of Al, Cd, Cr, Cu, Ni, Pb; 97% of Co, Mn, Zn; 83% of Fe; 35% of Mg; 21% of Na, SO4; and 49% of Cl were removed after 20 min of reaction with 70 gm L−1 dose. The precipitation of these metals as well as sulfate in the form of gypsum on the NCFA surface was detected by X-ray diffraction and field emission scanning electron microscope. The possible mineral phases were identified by PHREEQC geochemical modeling. However, this analysis does not evaluate the hazard of the treated water to aquatic life and human health. Therefore, water quality index (WQI) and hazard index (HI) is proposed in this study to evaluate the risk and identify the optimum dose and time for AMD treatment. These indices confirmed that AMD should be treated with 70 gm L−1 dose of NCFA for 20 min to safeguard human and aquatic life. This study gives a new direction to treat AMD effectively and identify its potential risk to living organisms.

The precipitation of Fe-compounds from acid mine drainage (AMD) and stream water polluted by AMD plays a crucial role in regulating pollutant migration and determining the impacts of AMD on aquatic ecosystems. It is thus essential to identify the nature of precipitates that form and to understand their stabilities in order to assess their environmental impact. This is a necessary prerequisite before an appropriate treatment program can be prepared. Various kinds of Fe-compounds have been found to precipitate from AMD, but not all of them have been investigated in detail. Schwertmannite is one of the Fe-compounds which need more investigation. Its stability constant was reported only once (Bigham et al., 1996). The purpose of this study is to determine the stability of schwertmannite and ferrihydrite as a function of the composition of the stream water from which they precipitate. Schwertmannite and ferrihydrite have been found to precipitate respectively from the stream waters of Imgok Creek and Osheep Creek in Kangwon-Do, Korea (Yu, 1996; Yu et al., 1996). Although Imgok and Osheep Creeks both drain what were once very actively operated mining areas and are polluted by AMD from the abandoned coal mines, their compositions are very different.

A trading ratio is required for water quality trading that involves nonpoint sources to compensate for the difficulty of determining nonpoint loadings, the stochastic characteristics of nonpoint loadings, and the uncertainty inherent in nonpoint source pollution control strategies. Compensating for risk and uncertainty is one of the primary justifications that a trading ratio greater than one is commonly considered. However, the appropriate specific value of a trading ratio remains unclear because of qualitative differences between point and nonpoint sources. This study addresses a growing concern with the analytical underpinnings of point/nonpoint trading ratios in water quality trading programs. This paper considers a basic spatial-temporal optimal control model assuming that the goal of the decision maker is to maximize ecological services from the watershed over a 10-year planning horizon given a predetermined budget each year to treat acid mine drainage problems. The level of pollution is assumed to be known but declining slightly over time as the acid mine drainage sources evolve. Resources are assumed to be spent on remediation projects that produce long term but declining treatment results. The primary goal of the model is to distribute the available resources over the basin by investing in restoration projects for targeted streams each year that will maximize the ecological return on this investment. The model reflects both the spatial reality of variations in flow, in pollution, in treatment, and in the ecological benefits produced and the intertemporal constraints of limited resources and the inability to move remediation programs once the initial investment is made. The resulting optimal temporal and spatial investment strategies are derived from solutions to a mixed integer programming problem obtained using the GAMS/CPLEX mixed integer programming package. The optimal results are then manipulated to evaluate trading ratios. A hypothetical acidity trading scenario is proposed in which a point source (a new coal mine operation subject to TMDL rules) uses credits generated through remediation projects at other sites from treatment of nonpoint sources within the same basin over the 10-year planning horizon. The trading ratio is the ratio of the expected amount of pollutant removed by treating the nonpoint source divided by the amount of additional pollution allowed from the new point source. Our results indcate that point/nonpoint trading ratios in proposed trading scenarios greater than one can be justified. For example, for a point/nonpoint trade between sources in adjacent stream segments, the appropriate trading ratio is 3.66 (or 3.66 to one). We note that current regulations give a lower bound for point/nonpoint trading ratio of 1:1. The upper bound for point/nonpoint trading ratio depends on technical aspects of the relative costs of treating the point source or treating nonpoint sources and reflects the limit of how much one is willing to pay for credits. A variety of factors determine trading ratios. First, to encourage trades with less uncertainty, trades in which the credit seller and buyer are in close proximity, and in which the credit seller is upstream, lower trading ratios are recommended. Second, trading ratios should be adjusted to favor trades that contribute to strategic restoration goals such as the improvement or maintenance of water quality in a particular basin. Reduced ratios provide incentives to promote the generation of credits in priority locations. Finally, trading ratios for same-pollutant trades should be lower than those for cross-pollutant trades. Three separate trading currencies would be used to account for same-pollutant acid mine drainage trades: pounds of iron, aluminum, and manganese. There would be little uncertainty in the outcome of a trade if the credit generator and buyer were affecting the same pollutant. In contrast, cross-pollutant trades that use a common currency such as ecological indices would be measured based on their ecological effect, which is one step removed from the actual changes in pollutant loads. The higher trading ratio required for cross-pollutant trades reflects this greater uncertainty. All potential trades considered in this study are interspatial trades; trades occur in the same basin; trades could be cross-pollutant trades within acid mine draiange and same-pollutant trades as well; and the credit buyer is the new coal mining operation; credit generators could be government agencies or nonprofit organization; and abandned mine lands and bond forfeiture sites can be sites where credits are generated.

Mineral types dominate microbiomes and biogeochemical cycling in acid mine drainage.

We examined whether there was a particular group of diatoms specific to acid mine drainage (AMD) sites and/or reclaimed sites in streams in a coal-mining region of southeastern Ohio. Streams were initially placed into 5 categories: 1) stream receiving AMD from an unreclaimed site, 2) stream receiving drainage from a site reclaimed prior to a 1972 regulation, 3) stream receiving drainage from a site reclaimed between 1972 and 1982 under Ohio Revised Code (ORC) 1513, 4) stream receiving drainage from site reclaimed after 1982 under the Surface Mining Control and Reclamation Act (SMCRA), and 5) stream not impacted by AMD. The diatom flora from riffles in each system and environmental parameters (pH, conductance, metal concentrations [Al, Fe, Mn], current velocity, width, and depth) were examined to assess the recovery of reclamation sites from mining. Canonical correspondence analyses separated heavily impacted AMD streams from other sites. Total alkalinity and pH were highly correlated to the 1st axis, and SO4, average depth, and temperature were influential in additional axes. Discriminant analyses of the diatom and environmental data sets were successful in assigning samples into 1 of the a priori stream categories (85% and 81.8% accuracy, respectively). AMD streams were characterized by a dominant flora of Eunotia exigua and Frustulia rhomboides. Streams that fluctuated between acidic and circumneutral pH (termed oscillating) had greater abundances of Brachysira vitrea than other study streams. Streams of intermediate water quality (i.e., reclaimed sites) were dominated by Achnanthidium minutissimum. There was a predictable relationship between post-reclamation stream water quality and diatom assemblages, which may prove useful in assessment and management of reclamation efforts.

&amp;lt;p&amp;gt;Mining is a crucial industry worldwide because of its economic and social importance. However, the increasing number of operating mines raises major concerns for health and the environment. The intense mining activity generates large quantities of wastes associated with several environmental problems. For example, the generation of acid mine drainages (AMD) by oxidation of sulphide ores stored in tailings deposits, leachates high concentrations of potentially harmful elements (PHEs), which poses severe pollution problems to the environment (aquatic and terrestrial ecosystems). This study evaluates the acid neutralisation capacity and the removal effectiveness of inorganic PHEs present in an AMD of different waste materials. This study is a first approach to future studies to develop pilot remediation studies using designed waste-derived Technosols. The waste used includes 4 mining wastes (iron oxide and hydroxide sludges [IO], marble cutting and polishing sludge [MS], gypsum spoil [GS], and carbonated waste from a peat extraction [CW]), 3 urban wastes (composted sewage sludge [WS], bio-stabilised material from municipal solid waste [BM], and vermicompost from pruning and gardening [VC]), and 3 agro-industrial wastes (2 solid olive-mill by-products [OW, OL] and composted greenhouse waste [GW]). All waste materials were spiked with the acidic water (AMD&amp;lt;sub&amp;gt;L&amp;lt;/sub&amp;gt;) prepared in the laboratory from the oxidation of pyritic tailings from the Aznalc&amp;amp;#243;llar mine accident (1998). Afterward, they were stirred for 24 h and filtered, separating the waste (solid phase) from the leachate (liquid phase). In the leachate (AMD&amp;lt;sub&amp;gt;L&amp;lt;/sub&amp;gt; treated), pH&amp;lt;sub&amp;gt;(L) 1:5&amp;lt;/sub&amp;gt;, EC&amp;lt;sub&amp;gt;(L) 1:5&amp;lt;/sub&amp;gt;, and inorganic PHEs concentrations were measured, the latter by ICP-MS. The acidic water showed a strongly acidic character (pH&amp;lt;sub&amp;gt;(L)&amp;lt;/sub&amp;gt; ~ 2.89), high salinity (EC&amp;lt;sub&amp;gt;(L)&amp;lt;/sub&amp;gt; ~ 3.76 dS m&amp;lt;sup&amp;gt;-1&amp;lt;/sup&amp;gt;), and high concentrations of PHEs. Among them, As, Cd, Cr, Cu, Ni, Pb, Sb, Th, Tl, U, V, Y, and Zn stood out since they far exceed various legal limits widely used worldwide and/or because their high toxicity to humans, animals, plants or microorganisms. The most abundant were Zn (32.21 mg l&amp;lt;sup&amp;gt;-1&amp;lt;/sup&amp;gt;), Cu (6.24 mg l&amp;lt;sup&amp;gt;-1&amp;lt;/sup&amp;gt;), As (2.86 mg l&amp;lt;sup&amp;gt;-1&amp;lt;/sup&amp;gt;), Sb (0.82 mg l&amp;lt;sup&amp;gt;-1&amp;lt;/sup&amp;gt;), Pb (0.60 mg l&amp;lt;sup&amp;gt;-1&amp;lt;/sup&amp;gt;), and Cd (0.45 mg l&amp;lt;sup&amp;gt;-1&amp;lt;/sup&amp;gt;). All wastes were effective in neutralising the acidic pH&amp;lt;sub&amp;gt;(L)&amp;lt;/sub&amp;gt; of the AMD, as the leachates showed pH&amp;lt;sub&amp;gt;(L)&amp;lt;/sub&amp;gt; close to 7. In contrast, changes in the EC&amp;lt;sub&amp;gt;(L)&amp;lt;/sub&amp;gt; have been very irregular among the wastes used. In general, all wastes have been effective in adsorbing the PHEs. Inorganic wastes have been much more effective than organic ones, with adsorption efficiencies above 95% for many of the PHEs (particularly for those in higher concentrations). The waste with the best remediation behaviour were IO, CW, MS, GS, and VC. Conversely, GW and WS were the worst at removing PHEs present in AMD. Therefore, this study shows that many of wastes tested are suitable for the construction of Technosols from these wastes to prevent soil pollution by AMD discharge.&amp;lt;/p&amp;gt;

Environmental concern during construction has become a serious matter, especially regarding water quality. Earth materials weather rapidly when excavated and in some instances produce deleterious products. One such product is acid drainage (AD). Weathering of Precambrian metasedimentary rocks excavated during road construction in the Southern Appalachian Mountains is a classic example of AD formed in this fashion. Before the problem was recognized, aquatic life was decimated in several “blue ribbon” trout streams. In order to address the problem of how to handle acid-producing material during construction, the Federal Highway Administration initiated studies resulting in development of guidelines. The guidelines suggest procedures for detecting and evaluating potential AD problems and provide suggestions for handling acid-producing material without requiring post-construction mitigation. Geologic mapping is the basic tool for assessing AD potential in an area. However, in covered areas geophysical methods have been applied effectively to detect the sulfide minerals primarily responsible for AD production. To determine the bottom-line as to whether sulfidic material has the potential to generate AD the use of an Acid-Base Accounting analysis has proven successful. If construction encounters acid-producing material and the cost:benefit of the project permits, AD can be successfully abated by encapsulation of the material within specially designed embankments.

This study employs chemical fractionations of sedimentary metals and analyses of sediment arcellacean (thecamoebian) faunas to study the ecological effects of mining wastewaters in a boreal lake bay that receives metal-rich waters from a Cu mine. Sediment chemistry and arcellacean species compositions were analyzed from both surface sediment samples and a sediment profile to investigate spatial and temporal changes in mine water pollution and biota. Based on the results, geochemical gradients in the area are caused by dispersal and dilution of metal-rich, low-pH mine waters entering the lake; transport and focusing of fine grained metal precipitates and sulphate in the deep areas of the bay; increase in pH due to sulphate reduction and mobilization of redox-sensitive elements from deep water sites; and precipitation of the mobilized metals at shallower sites. Arcellacean species compositions change systematically with increasing distance from the source of pollution and species diversity as well as concentrations of tests in the samples increase as well. Fe:Mn ratio and adsorbed Al explained variation in surface sediment arcellaceans with statistical significance. Fe:Mn ratio is an indicator of the overall geochemical environment (Eh, pH), while the toxicity of Al in aquatic environments is well known. Changes in arcellacean species and geochemistry in the long core suggest that before the mine closure in 1983, mine waters differed in nature from the present acid drainage and metals such as Cu, Co, Zn and Ni may have affected arcellaceans at that time.