Gold Mining Operations Research Articles

Food Sovereignty: A Framework for Assessing Agrarian Responses to Climate Change in the Philippines

INTRODUCTIONThe Philippines is one of the foremost countries affected by climate change, with increasing incidence of super typhoons, droughts, floods, and changing rain patterns - all of which exacerbate existing food insecurity, poverty, and ecological degradation (United Nations University & Alliance Development Works, 2014; Yumal et al., 2011). In response to these challenges, the development and diffusion of adaptation and mitigation strategies are necessary to enhance agrarian resiliency. Our ongoing research involves the assessment of food sovereignty pathways in Ecuador, Brazil, Canada, and the Philippines. Here, we report on our progress in using food sovereignty principles to develop an assessment framework for climate resiliency and food security among a network of smallholder agrarian systems in the Philippines. The objective of this research project is to analyze how and to what extent these smallholder farmers are enhancing their livelihoods; responding to loss and damage incurred due to climate change; and serving as catalysts for climate change adaptation, mitigation, and overall resiliency through farmer-led agricultural development initiatives.The Magsasaka at Siyentipiko para sa Pag-Unlad ng Agrikultura (Farmer-Scientist Partnership for Agricultural Development, MASIPAG) is a national Filipino farmer-led network engaging in agroecological strategies to promote the sustainable use and management of biodiversity through farmers' control of genetic and biological resources, agricultural production, and associated knowledge (Medina, 2009). Since MASIPAG's establishment in the 1980s, the network has grown from 50 farmers to an estimated 35,000 farmers today. Our team is working with MASIPAG to assess the degree and scope of their effectiveness in facilitating livelihood resilience, especially in the context of climate change.The challenge with this research lies in capturing the range of complex and interrelated dimensions encompassed in agrarian systems. Another challenge is developing new methodological approaches to empirically measure the outcomes of dynamic agroecological strategies and their overall impact on climate resiliency and food security. In response, we propose a systems-based approach built on the principles of 'food sovereignty' as a framework for investigating these dynamics and assessing their impact on both food security and climate resiliency.In the Philippines, an estimated 17 percent (16.4 million) of Filipinos do not meet their nutritional requirements and basic needs (Food and Agriculture Organization, 2012). A quarter of the population (24.2 million) lives in poverty (World Bank Group, 2012) and poverty is most severe and widespread among indigenous peoples and small-scale farmers (International Fund for Agricultural Development, 2009). Contributors to poverty and food insecurity include land reform policies dating back to 1988 that have been ineffective at breaking up and redistributing privately owned lands acquired during Spanish colonialism (Bello, 2001); multinational agricultural companies that are expanding industrial palm oil, banana, and pineapple plantations (Franco & Borras, 2007); and large-scale gold and copper mining operations that are destroying landscapes and watersheds (CEC-Philippines, 2012). These factors perpetuate a cycle of landlessness and poverty among farmers and contribute to the ongoing concentration of wealth and power in the Philippines (Ballesteros & de la Cruz, 2006; Borras, 2007).Major reports (De Schutter, 2010; McIntyre et al., 2009; United Nations Conference on Trade and Development, 2013), high profile case studies (Altieri & Koohafkan, 2008; Bachmann, Cruzada, & Wright, 2009; Holt-Gimenez, 2002), and reviews (Altieri, Funes-Monzote, & Petersen, 2012; Lin et al., 2011) suggest that in order to address worsening inequalities, limited resources, and degrading ecological conditions while improving climate resiliency, agrarian systems should facilitate effective social processes for community empowerment as well as exhibit high levels of diversity, synergy, recycling, and integration. …

Inuit knowledge and environmental assessment in Nunavut, Canada

Related climatic, socioeconomic and political pressures act on socio-ecological systems and drive change. Co-management boards such as the Nunavut impact review board (NIRB) in Canada’s north are linked, multi-level institutions that attempt to involve aboriginal stakeholders in decision making and collaborative learning through the application of traditional knowledge (TK), among other things. This case study describes the process of collecting and applying TK in the review phase of regulatory environmental impact assessment (EA) in Nunavut. Through a review of documentation from the Meadowbank EA, currently the only operating gold mine in the region, the type of knowledge collected and how it is applied to inform impact prediction, planning, design and monitoring are described. The results show TK in the form of factual observations, and past and current uses of land are most useful and complement modern science. Strategies for management, ethics, values and spiritual relationships are not directly applicable to project impacts, yet these facets of TK can be communicated experientially to project proponents through the EA process that is lengthy and encourages face to face contact with local stakeholders. Multi-level governing boards provide a forum for dialogue to combine TK and modern scientific principles—a good example for a broader science of sustainability. The cumulative impacts of ever more complex projects pose a challenge to the accuracy of traditional knowledge applied to EA.

Effects of large‐scale gold mining on migratory behavior of a large herbivore

Loss of migratory corridors has been identified as an important ecological issue among species that exhibit long‐distance migration worldwide. Increased mineral exploration and development has raised the level of concern over the protection of terrestrial migration routes for ungulates. Mineral exploration and other types of development may adversely affect migratory corridors for large herbivores, but little is known about functional effects on migratory behavior and resource selection. To address these important questions we examined movement patterns and resource selection to understand the effects of an operating gold mine on migratory pathways of mule deer (Odocoileus hemionus). We captured and applied radio collars to female mule deer (n = 43) on the migratory pathway and in the proximity of an active mine in the Ruby Mountains of eastern Nevada. We used Brownian Bridge Movement Models to delineate stopover sites for each individual during both the autumn and spring migrations. We calculated linear efficiency of movement along the migration path and movement rate between stopover locations outside and within the mining area to determine the effects of the mine on movement patterns. We also used resource selection functions to determine if mule deer avoided areas with extensive excavation and disturbance of the land surface when navigating through the mine complex. Our results indicated greater linear efficiency of movement along the migration path and movement rates between stopover locations outside the mine when compared with movement through the mine complex. Additionally, mule deer that migrated through the mine complex avoided the highest disturbance levels by spending the majority of their time in undisturbed habitat patches. These results suggest an increase in energy expenditure of mule deer navigating through highly disturbed areas, which may have fitness consequences for migratory animals. Such increases in energy expenditure during migration may decrease survival or productivity of migratory populations of large, terrestrial mammals.

Gas-exchange chamber analysis of elemental mercury deposition/emission to alluvium, ore, and mine tailings

Deposition of mercury (Hg) from the atmosphere is an important source of this contaminant to terrestrial ecosystems. Once deposited, all forms of Hg can be retained or emitted back to the atmosphere. Distinguishing between volatilization of geogenic or indigenous Hg and that deposited from the atmosphere is difficult. Field flux measurements in the general area of two industrial scale gold mining operations, showed local deposition of Hg emitted from point and nonpoint sources, and subsequent re-emission. The work presented in this paper investigated deposition/emission of elemental Hg to and from alluvium and two mine materials before, during, and after exposure to high air concentrations, for both wet and dry conditions, using a laboratory gas exchange chamber and a Hg permeation source. In general, results showed a range in mean elemental Hg deposition velocities ranging from 0.13 to 0.46cms−1 that varied with material. A significant influence of atmospheric ozone (O3) on flux was observed that depended on the material and whether wet or dry. A synergistic relationship existed between O3 and light promoting Hg flux, and flux was also influenced by material grain size, chemistry, and primary mineralogy.

A Study of Residual Cyanides and Potential Stabilities in Tailings Storage Facility of Gold Mining Operation

The study aimed to investigate residual cyanides and their potential stabilities in tailings from a gold processing plant deposited in the Tailings Storage Facility (TSF) of a gold mining site. For this purpose, several samples of tailings were taken from the recently abandoned TSF to a depth of 2.5 meters, representing 1 to 2 years old tailings. The samples were analyzed for pH, metals, residual cyanides, and Net Acid Generation Test (NAG test). The results showed that, in all samples, pH values were neutral to slightly alkaline. Fe concentrations were relatively high (22,800-35,000 mg kg-1) indicating that Fe can readily react with free cyanide (CN-) to form iron cyanide complexes (strong metal cyanide complexes). The residual cyanide concentration in tailings was found to be very low; free cyanide (CNFree), weak acid dissociable cyanide (CNWAD), strong acid dissociable cyanide (CNSAD) and total cyanide (CNT) were in the range of 0.16-0.64, 0.37-1.06, 1.96-3.89 and 2.33-4.95 mg kg-1, respectively. Cyanides in the tailings were predominantly strong metal cyanide complexes being more stable to dissociate. Total cyanide (CNT) concentration was quite low compared with Thailand’s environmental regulations for soil quality standards andwere environmentally insignificant. The NAG test for all samples revealed that NAG pH was in the range of 5.02-6.10 and NAG was in the range of 0.08-0.31 kg H2SO4t-1indicating all samples have low or non-acid forming potentials. The findings indicated a potential to form a high proportion of strong metal cyanide complexes in the tailings, which is difficult to dissociate and releasehigh toxic cyanide to the environment.

Green Gold—Dirty Gold, Tadó, Dept. Chocó, Colombia

In place of mercury, small-scale alluvial gold miners in Tadó, Dept. Chocó, Colombia produce “green gold” (oroverde) using locally available plant extracts. The leaves of Balso (Ochroma pyramidale) and Malva (Hibiscus furcellatus) are crushed by hand and are mixed with water to make a foamy liquid that is added to the gold pan (batea) instead of mercury. After the plant extract is added, the gold, magnetite, and other heavy minerals sink and the lighter minerals are floated out of the gold pan. For final clean-up, a combination of other methods may be used. However, ICP (Inductively Coupled Plasma) analyses indicate that even green gold contains 208 - 4530 ppm Hg—this mercury may have been released from dragas or other small-scale gold mining operations that continue to use mercury; coal burning; volcanism; or native mercury released from cinnabar occurrences. ICP also indicates 308 - 106,000 ppm Ag and 452 - 585 ppm Pt.

A review of mercury concentrations in freshwater fishes of Africa: patterns and predictors.

The methylated form of mercury (methylmercury) is a potent neurotoxic chemical and a contaminant of concern for fisheries because of its potential effects on ecosystem and human health. In Africa, inland fisheries are a crucial component of food and economic security, yet little information is available on mercury (Hg) contamination trends. The authors compiled published data on Hg contamination in African freshwater fishes, invertebrates, and plankton, as well as on potential drivers of Hg concentrations in these organisms. From 30 identified studies the authors assembled 407 total Hg concentrations from 166 fish species, 10 types of invertebrates, and various plankton, distributed across 31 water bodies in 12 countries. In fishes, total Hg concentrations, expressed as mean (± standard deviation) per location, averaged 156.0 ± 328.0 ng/g wet weight and ranged from 5.5 ng/g wet weight to 1865.0 ng/g wet weight. Only locations with nearby artisanal and small-scale gold mining operations had mean Hg concentrations above the World Health Organization/Food and Agriculture Organization's recommended guideline for fish (500 ng/g wet wt). The authors used mixed models to detect relationships between fish Hg concentrations and trophic level, mass, latitude, and chlorophyll a. Mass, trophic level, and latitude were all positive predictors of Hg concentration, confirming the presence of Hg bioaccumulation and biomagnification in African fishes. Although strong trends in Hg concentrations were evident, the present study also highlights limited availability of Hg data in Africa.

Large-scale drivers of malaria and priority areas for prevention and control in the Brazilian Amazon region using a novel multi-pathogen geospatial model.

BackgroundMost of the malaria burden in the Americas is concentrated in the Brazilian Amazon but a detailed spatial characterization of malaria risk has yet to be undertaken.MethodsUtilizing 2004-2008 malaria incidence data collected from six Brazilian Amazon states, large-scale spatial patterns of malaria risk were characterized with a novel Bayesian multi-pathogen geospatial model. Data included 2.4 million malaria cases spread across 3.6 million sq km. Remotely sensed variables (deforestation rate, forest cover, rainfall, dry season length, and proximity to large water bodies), socio-economic variables (rural population size, income, and literacy rate, mortality rate for children age under five, and migration patterns), and GIS variables (proximity to roads, hydro-electric dams and gold mining operations) were incorporated as covariates.ResultsBorrowing information across pathogens allowed for better spatial predictions of malaria caused by Plasmodium falciparum, as evidenced by a ten-fold cross-validation. Malaria incidence for both Plasmodium vivax and P. falciparum tended to be higher in areas with greater forest cover. Proximity to gold mining operations was another important risk factor, corroborated by a positive association between migration rates and malaria incidence. Finally, areas with a longer dry season and areas with higher average rural income tended to have higher malaria risk. Risk maps reveal striking spatial heterogeneity in malaria risk across the region, yet these mean disease risk surface maps can be misleading if uncertainty is ignored. By combining mean spatial predictions with their associated uncertainty, several sites were consistently classified as hotspots, suggesting their importance as priority areas for malaria prevention and control.ConclusionThis article provides several contributions. From a methodological perspective, the benefits of jointly modelling multiple pathogens for spatial predictions were illustrated. In addition, maps of mean disease risk were contrasted with that of statistically significant disease clusters, highlighting the critical importance of uncertainty in determining disease hotspots. From an epidemiological perspective, forest cover and proximity to gold mining operations were important large-scale drivers of disease risk in the region. Finally, the hotspot in Western Acre was identified as the area that should receive highest priority from the Brazilian national malaria prevention and control programme.Electronic supplementary materialThe online version of this article (doi:10.1186/1475-2875-13-443) contains supplementary material, which is available to authorized users.

Strengths Amidst Vulnerabilities: The Paradox of Resistance in a Mining-Affected Community in Guatemala

The influence of large-scale mining on the psychosocial wellbeing and mental health of diverse Indigenous communities has attracted increased attention. In previous reports, we have discussed the influence of a gold mining operation on the health of a community in the Western highlands of Guatemala. Here, we discuss the community strengths, and acts of resistance of this community, that is, community processes that promoted mental health amidst this context. Using an anti-colonial narrative methodology that incorporated participatory action research principles, we developed a research design in collaboration with community leaders and participants. Data collection involved focus groups, individual interviews and photo-sharing with 54 men and women between the ages of 18 and 67. Data analysis was guided by iterative and ongoing conversations with participants and McCormack's narrative lenses. Study findings revealed key mechanisms and sources of resistance, including a shared cultural identity, a spiritual knowing and being, ‘defending our rights, defending our territory,’ and, speaking truth to power. These overlapping strengths were identified by participants as key protective factors in facing challenges and adversity. Yet ultimately, these same strengths were often the most eroded or endangered due the influence of large-scale mining operations in the region. These community strengths and acts of resistance reveal important priorities for promoting mental health and wellbeing for populations impacted by large-scale mining operations. Mental health practitioners must attend to both the strengths and parallel vulnerabilities that may be occasioned by large-scale projects of this nature.

Pilot Assessment of Hazards and Health Effects in a Small-Scale Artisanal Gold Mining Community in Ghana

Background: Small-scale artisanal gold mining (SAGM) operations contribute a substantial fraction to the exports of some countries – for example, as much as 40% in the West African nation of Ghana....

Hydrological controls on methylmercury distribution and flux in a tidal marsh.

The San Francisco Estuary, California, contains mercury (Hg) contamination originating from historical regional gold and Hg mining operations. We measured hydrological and geochemical variables in a tidal marsh of the Palo Alto Baylands Nature Preserve to determine the sources, location, and magnitude of hydrological fluxes of methylmercury (MeHg), a bioavailable Hg species of ecological and health concern. Based on measured concentrations and detailed finite-element simulation of coupled surface water and saturated-unsaturated groundwater flow, we found pore water MeHg was concentrated in unsaturated pockets that persisted over tidal cycles. These pockets, occurring over 16% of the marsh plain area, corresponded to the marsh root zone. Groundwater discharge (e.g., exfiltration) to the tidal channel represented a significant source of MeHg during low tide. We found that nonchannelized flow accounted for up to 20% of the MeHg flux to the estuary. The estimated net flux of filter-passing (0.45 μm) MeHg toward estuary was 10 ± 5 ng m(-2) day(-1) during a single 12-h tidal cycle, suggesting an annual MeHg load of 1.17 ± 0.58 kg when the estimated flux was applied to present tidal marshes and planned marsh restorations throughout the San Francisco Estuary.

Lessons From The Lives of Two Dams

Many embankment dams completed during the first six decades of the 20th century have been found deficient relative their ability to resist currently anticipated levels of seismic shaking and probable maximum flood. In this Fourth Victor de Mello Lecture, two recent case histories are described. One is a hydraulic fill structure completed in 1920 that is founded on alluvial material, some zones of which are susceptible to liquefaction. The other is a zoned earthfill dam completed in 1956 that is founded over a channel filled with loose, uncompacted, hydraulically placed tailings from gold mining operations. Each dam has been upgraded in phases over periods of several decades using different strategies and ground improvement technologies to improve stability and reduce failure risks. Several take away lessons from these experiences concerning current risk mitigation strategies, the importance of correct soil and site characterization, and implementation and effectiveness of different ground stabilization and improvement methods are presented.

Gold mining areas in Suriname: reservoirs of malaria resistance?

BackgroundAt present, malaria cases in Suriname occur predominantly in migrants and people living and/or working in areas with gold mining operations. A molecular survey was performed in Plasmodium falciparum isolates originating from persons from gold mining areas to assess the extent and role of mining areas as reservoirs of malaria resistance in Suriname.MethodsThe status of 14 putative resistance-associated single nucleotide polymorphisms in the pfdhfr, pfcrt, pfmdr1, and pfATP6 genes was assessed for 28 samples from gold miners diagnosed with P. falciparum malaria using polymerase chain reaction amplification and restriction fragment length polymorphism analysis, and the results were compared with earlier data from nonmining villagers.ResultsIsolates from miners showed a high degree of homogeneity, with a fixed pfdhfr Ile51/Asn108, pfmdr1 Phe184/Asp1042/Tyr1246, and pfcrt Thr76 mutant genotype, while an exclusively wild-type genotype was observed for pfmdr1 Asn86 and pfdhfr Ala16, Cys59, and Ile164, and for the pfATP6 positions Leu263/Ala623/Ser769. Small variations were observed for pfmdr1 S1034C. No statistically significant difference could be detected in allele frequencies between mining and nonmining villagers.ConclusionDespite the increased risk of malaria infection in individuals working/living in gold mining areas, we did not detect an increase in mutation frequency at the 14 analyzed single nucleotide polymorphisms. Therefore, mining areas in Suriname cannot yet be considered as reservoirs for malaria resistance.

A Lantern Retort for Small-Scale Gold Extraction

Two major retorts used in small-scale gold mining operations to reduce mercury emissions, during amalgam distillation are the steel and thermex retorts. Steel retorts are not very popular due to the reported darkening of gold after retorting. In addition, its opaque nature prevents miners from observing the process directly. The Thermex glass retort introduced by the United Nations Industrial Development Organisation (UNIDO) is also not patronised due to the extended heating periods resulting from the low thermal conductivity of glass. This paper describes a new retort, the Lantern retort, a combination of highly conductive steel with transparent glass, and therefore, a potential solution to the above concerns. The Lantern retort has a shorter warm-up and amalgam distillation time, and the rate of heating is 1.81oC/s while that of the Thermex is 1.49oC/s. For an amalgam of mass 20 g, 900 s was required to carry out complete distillation in the Lantern retort as against 2100 s in the Thermex. The height of the distillation column of the Lantern retort required to reduce mercury loss to below 1%, as it is with the Thermex retort, is 2.5 cm. Other advantages of the Lantern retort are that, it is less expensive and can withstand the harsh terrain of small-scale gold mining.

The Challenges of Supply Chain in the Gold Mining Sector of Obuasi Municipality of Ghana

Gold mining industry represents an important source of socio-economic development in most economies. Ghana has had its fair share of the benefits the mining sector brings by way of direct revenue generation and job creation. In spite of this significant contribution from gold mining, the sector appears to be facing various forms of challenges. This study aims at assessing the supply chain challenges facing the gold mining operations in Obuasi and its environs in the Ashanti region of Ghana. A combination of qualitative and quantitative methods with case study strategy was used in the study. Primary data was collected from field survey through questionnaires, semi-structured interviews and observation. The data was analysed using quantitative and qualitative approaches. The major supply chain challenges found to be facing the mining sector in Obuasi include supply of low quality products, unreliable or variable lead times, non-availability of local firms of international standard, fluctuation in Gold prices on the international market, high transportation cost and violence and sporadic attack from the communities. It is recommended that the mining firms should involve their key and strategic suppliers in product designs and development of specifications. Also, improving upon information sharing and building trust and transparency and developing the capacities of their key suppliers to improve the performances of the entire supply chain could also deal with delays and quality related supplies. Finally the Ministry of Energy, the Environmental Protection Agency and other institutions should collaborate with the mining firms to deal with issues of environmental pollution and matters of perceived inadequate compensation to community members whose farm lands get destroyed by the mining activities to address any unhealthy conflicts between the mining firms and the communities.

Joint stochastic optimisation of short and long term mine production planning: method and application in a large operating gold mine

A new multistage stochastic mine production scheduling approach is developed and tested in a large operating gold mine. The approach takes short scale orebody information in the form of grade control data into account. As simulated orebodies used in stochastic long term mine planning are based on sparse exploration data while grade control data are unavailable at the time of production scheduling, the short scale information is simulated stochastically. Stage 1 of the approach simulates high density future grade control data based on exploration data and grade control in previously mined out parts of a deposit. In stage 2, the technique of conditional simulation by successive residuals enables preexisting simulated orebody models to be updated using the simulated future grade control information. Stage 3 is based on a stochastic programming mine scheduling formulation that handles jointly multiple simulated orebody models from stage 2, and accommodates both maximising net present value (NPV) and minimising deviations from expected production targets. Stage 4 includes quantification of risk in the production schedules generated, comparisons and reporting. The application at a large operating gold mine demonstrates that the proposed approach is practical, and adds value to the operation. The approach is shown to deliver additional ore (3·6 Mt more) and metal (2·6 Mg more) which matches the mines reconciliations, unlike the conventional schedule, and results in a cumulative NPV which is on average 7·7 million AUD higher than that of a stochastic schedule without the simulated grade control data. The NPV is 230 million AUD higher compared to the NPV from the actual schedule of the mine. An additional key contribution of the proposed approach is the compliance of short- to long term production schedules and performance, leading to higher probability of meeting production targets and increased productivity. Given the capital intensity of mining projects, this contribution can be critically important to mining operations.

Multiple methods for regional- to mine-scale targeting, Pataz gold field, northern Peru

Gold production in the Pataz district, northern Peru, is derived from mesothermal veins hosted by the Pataz batholith and basement-hosted epithermal and carbonate–base metal veins. At the regional scale, processing of Advanced Spaceborne Thermal Emission and Reflection Radiometer data can be used to delineate district-scale argillic alteration. One such area extends for tens of kilometres NNW of Vijus in the Maranon Valley. At the southern end of this area, basement-hosted quartz–carbonate–sulfide veins in faults support artisanal gold-mining operations. SEM analyses show that the alteration envelopes around these faults are dominated by illitic clays. These artisanal gold workings highlight the economic potential of the largely unexplored parts of the district-scale argillic alteration zone, further north. At the district scale, paleostress modelling maps areas of low minimum stress during Carboniferous ENE–WSW shortening, based on a new 1:25 000 geological map of the Pataz district. The resulting distribution of low minimum stress is used to predict sites of rock fracture under high fluid pressure, and consequent vein formation. These areas of low minimum stress occupy 11% of the modelled area but contain 50% of the known veins in the Pataz district. Some areas of low minimum stress contain no known veins, and where these are poorly explored or poorly exposed, they are proposed as potential targets for gold exploration. In combination with SEM microanalysis, ASD hyperspectral reflectance analysis of drill core samples shows that visible proximal sericitic alteration around batholith-hosted auriferous veins is predominantly phengitic illite. Automated software interpretation of ASD reflectance spectra using The Spectral Assistant shows that sericite in cryptic alteration distal from auriferous veins varies from mainly illite adjacent to the phengitic illite zone, to more distal muscovite. Reactivation of faults and mineralised vein contacts during the largely Cenozoic Andean orogeny produced chlorite alteration that locally overprints proximal phengitic illite alteration. ASD spectrometry identifies relict phengitic illite in some chloritic alteration zones and thus indicates proximity to mineralised veins at the deposit scale. Elevated pathfinder element concentrations within proximal phengitic illite alteration zones around batholith-hosted veins do not extend more than a few metres beyond the visible alteration envelope. The alkali alteration index [(Rb + Cs)/Th]N is elevated above background levels for up to 15 m beyond the visible sericite alteration zone in one of two holes investigated. In the other hole, both [(Rb + Cs)/Th]N and 3K/Al can be used as a lode-scale vector to gold-bearing veins within broad intersections of visible sericite alteration.

Testing and modeling the influence of reclamation and control methods for reducing nonpoint mercury emissions associated with industrial open pit gold mines

Industrial gold mining is a significant source of mercury (Hg) emission to the atmosphere. To investigate ways to reduce these emissions, reclamation and dust and mercury control methods used at open pit gold mining operations in Nevada were studied in a laboratory setting. Using this information along with field data, and building off previous work, total annual Hg emissions were estimated for two active gold mines in northern Nevada. Results showed that capping mining waste materials with a low-Hg substrate can reduce Hg emissions from 50 to nearly 100%. The spraying of typical dust control solutions often results in higher Hg emissions, especially as materials dry after application. The concentrated application of a dithiocarbamate Hg control reagent appears to reduce Hg emissions, but further testing mimicking the actual distribution of this chemical within an active leach solution is needed to make a more definitive assessment. Implications: Laboratory and field measurements of mercury flux from materials typically found at large open pit gold mines in Nevada indicate that non-point-source mercury emissions are a significant component of total mercury emissions, but that these nonpoint emissions can be significantly reduced by postmining capping and reclamation, and possibly by chemical treatments of leach ore and tailings waste.

Assessing the impacts of gold mining assessing the impacts of gold mining operations on river sediments and water samples from ilesa west local government area ILESA West Local Government Area of Osun State, Nigeria

Gold mining operations started in the Ilesa-West Local Government Area of Osun state Nigeria in early 1950s. Though official mining operation stopped in mid 1990s, illegal mining is still active in the area till today. Twelve (12) villages were selected for the study based on the high rate of mining activities. The villages are Mokuro, Oke-Ora, Okutu-Omo, Oko Ogboni, Alaba, Itagunmodi, Ariyelepe, Alaba-Oke, Iyere, Igun, Aba-Isobo and Sabo, all in Ilesa South West Local Government area of Osun state, Nigeria within longitude 4 0 36 1 - 4 0 42 1 E and latitude 7 0 30 1 - 7 0 34 1 N. A total of 51 stream water and sediment samples were randomly collected from water sources available to the communities. Stream water samples collected were analyzed for heavy metals using atomic absorption spectrophotometer (AAS) while associated stream sediments were analyzed with x-ray fluorescence spectrometer (XRF). Heavy metals analyzed in both sample types include As, Cu, Cd, Pb, Fe, Cr, Mn, Zn, Zr, and Sr. Results obtained showed the stream waters to be richly concentrated with toxic metals in the range of As(0.002± 0.001 to 0.004± 0.001 mg/l), Cd (0.003±0.001 to 0.034± 0.004 mg/l), Pb (0.002± 0.001 to 0.017±0.003mg/l), Cu(0.078±0.003 to 2.326±0.004 mg/l), Zn(0.013 ±0.004 to 1.937±0.015mg/l), Fe (0.013±0.005 to 0.825±0.085mg/l), Mn (0.002±0.001 to 0.016±0.001mg/l) and Cr (0.009 ± 0.002 to 0.069 ± 0.031mg/l). The variation of heavy metals in stream water samples are Cu>Zn>Cr>Fe>Cd>As>Pb>Mn. Similar contamination of the stream sediments were observed as XRF results showed the sediments to have high concentration of heavy metals As, Cd, Pb ,Cu and Cd clearly above regulated limits. Enrichment Factor of the elements obtained showed high contamination of both the stream water and sediments with toxic metals as a result of high illegal gold mining operations in the area under study.

Wetland-based passive treatment systems for gold ore processing effluents containing residual cyanide, metals and nitrogen species

Gold extraction operations generate a variety of wastes requiring responsible disposal in compliance with current environmental regulations. During recent decades, increased emphasis has been placed on effluent control and treatment, in order to avoid the threat to the environment posed by toxic constituents. In many modern gold mining and ore processing operations, cyanide species are of most immediate concern. Given that natural degradation processes are known to reduce the toxicity of cyanide over time, trials have been made at laboratory and field scales into the feasibility of using wetland-based passive systems as low-cost and environmentally friendly methods for long-term treatment of leachates from closed gold mine tailing disposal facilities. Laboratory experiments on discrete aerobic and anaerobic treatment units supported the development of design parameters for the construction of a field-scale passive system at a gold mine site in northern Spain. An in situ pilot-scale wetland treatment system was designed, constructed and monitored over a nine-month period. Overall, the results suggest that compost-based constructed wetlands are capable of detoxifying cyanidation effluents, removing about 21.6% of dissolved cyanide and 98% of Cu, as well as nitrite and nitrate. Wetland-based passive systems can therefore be considered as a viable technology for removal of residual concentrations of cyanide from leachates emanating from closed gold mine tailing disposal facilities.