Cheng, Y. C., Nakajima, K., Nansai, K., Seccatore, J., Veiga, M. M., & Takaoka, M. (2022). Examining the inconsistency of mercury flow in post-Minamata Convention global trade concerning artisanal and small-scale gold mining activity. Resour. Conserv. Recycl., 185, 106461.
Abstract: In 2017, the Minamata Convention (MC) on mercury (Hg) control entered into force. However, whether the MC is effective and how it reshapes the global Hg flow remain unclear. In this study, we established a method to detect inconsistencies in data on global Hg trade, and calculated the gap between the demand and supply of Hg to the artisanal and small-scale gold mining (ASGM) sector (i.e., the largest source of Hg emissions globally) in 39 countries across four regions. According to our results, inconsistencies in statistical data concerning Hg for ASGM activities exist in both Africa and Central and South America. Asia showed a considerably lower amount of Hg applied to ASGM than apparent Hg consumption; nevertheless, the largest consumer of Hg was Asia, predomi-nantly China and India. Many countries in which ASGM is conducted are already MC parties; however, only few submitted their national action plans (NAPs) or have established/enforced specific laws to curb Hg use in ASGM. Analysis of Hg-related trade information suggests that in 2017, the trade of metallic Hg disappeared in some African and Central and South American countries, but new trade flows of goods with higher Hg content emerged. The method established in this study can support the search for countries implementing ASGM with hidden Hg use and flows, thereby contributing to the planning of further Hg control regulations. To enforce sound Hg management, the submission of NAPs should also be promoted in addition to the expansion of MC parties.
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Cheng, Y. C., Watari, T., Seccatore, J., Nakajima, K., Nansai, K., & Takaoka, M. (2023). A review of gold production, mercury consumption, and emission in artisanal and small-scale gold mining (ASGM). Resour. Policy, 81, 103370.
Abstract: Artisanal and small-scale gold mining (ASGM) is one of the largest sources of Hg emissions and is critical for addressing the Hg problem. Due to scarce and punctual statistics provided by governments and agencies, there is almost no accurate data on ASGM production, Hg use, and emissions. In this study, we surveyed different ap-proaches to estimate ASGM production and collected data from different sources, including academic papers and technical reports. Globally, 380-870 tonnes of gold is produced by ASGM each year, with a median value of 520 tonnes. The Hg use in the ASGM sector was estimated to be 640-1000 tonnes each year, with a median value of 892 tonnes. Consequently, 248-838 tonnes of Hg are emitted from the ASGM sector each year, with a median value of 615 tonnes. However, significant discrepancies were found in the data calculated using different ap-proaches, particularly in countries where the estimates were large, such as China. To obtain a more accurate picture of global ASGM activities, a general estimation approach combining specific studies of dominant coun-tries is necessary. For better management of ASGM in the future, developing a solid baseline and comprehensive future projection scenarios and establishing international collaboration to construct guidance on ASGM are recommended.
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Pina, S., Candia-Onfray, C., Hassan, N., Jara-Ulloa, P., Contreras, D., & Salazar, R. (2021). Glassy Carbon Electrode Modified with C/Au Nanostructured Materials for Simultaneous Determination of Hydroquinone and Catechol in Water Matrices. Chemosensors, 9(5), 88.
Abstract: The simultaneous determination of hydroquinone and catechol was conducted in aqueous and real samples by means of differential pulse voltammetry (DPV) using a glassy carbon electrode modified with Gold Nanoparticles (AuNP) and functionalized multiwalled carbon nanotubes by drop coating. A good response was obtained in the simultaneous determination of both isomers through standard addition to samples prepared with analytical grade water and multivariate calibration by partial least squares (PLS) in winery wastewater fortified with HQ and CT from 4.0 to 150.00 mu M. A sensitivity of 0.154 mu A mu M-1 and 0.107 mu A mu M-1, and detection limits of 4.3 and 3.9 mu M were found for hydroquinone and catechol, respectively. We verified the reliability of the developed method by simultaneously screening analytes in spiked tap water and industrial wastewater, achieving recoveries over 80%. In addition, this paper demonstrates the applicability of chemometric tools for the simultaneous quantification of both isomers in real matrices, obtaining prediction errors of lower than 10% in fortified wastewater.
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Seccatore, J., & de Theije, M. (2017). Socio-technical study of small-scale gold mining in Suriname. J. Clean Prod., 144, 107–119.
Abstract: Small-scale gold mining is Suriname's main economic sector, producing about two thirds of the nation's gold. Despite this, the sector is only very loosely regulated and most small-scale mining activities are informal. Surinamese miners are only a minority: the majority are Brazilian migrants, who have no right to the land and therefore have to pay a percentage of their production for land use. This study reports the findings of a field mission to small-scale mines in the region of Brokopondo reservoir. We document the technical aspects of small-scale gold mining in Suriname and contextualize this technology to social issues to identify links with cultural, political and sociological factors. Our findings show that informality and insecurity lead to a mine management culture that applies short-term solutions, such as cheap but polluting and inefficient technologies, and fails to produce stable, long-term mining conditions for clean, efficient technology and secure business planning. We conclude that the social context of the mining economy in Suriname strongly interacts with the technologies employed. (C) 2016 Elsevier Ltd. All rights reserved.
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Shanmugaraj, K., Mangalaraja, R. V., Campos, C. H., Singh, D. P., Aepuru, R., Thirumurugan, A., et al. (2023). Gold nanoparticles decorated two-dimensional TiO2 nanosheets as effective catalyst for nitroarenes and rhodamine B dye reduction in batch and continuous flow methods. Inorg. Chem. Commun., 149, 110406.
Abstract: Our environment is greatly endangered by the accumulation of various toxic organic pollutants that are continually produced through unavoidable human needs and the industrialization process. Herein, we report highly active gold nanoparticles (AuNPs) immobilized on two-dimensional (2D) TiO2 nanosheets (AuNPs-TiO2NSs) as a catalyst for the catalytic reduction of nitroarenes (NAs) such as 4-nitroaniline (4-NA), 4-(4-nitrophenyl)morpholine (4-NM), 4-(2-fluoro-4-nitrophenyl)morpholine (4-FNM) and rhodamine B (RhB) dye in the presence of sodium borohydride (NaBH4) medium. Initially, TiO2NSs are prepared by the hydrothermal treatment followed by the modification with 3-aminopropyl-trimethoxysilane (APTMS) coupling agent for strong anchoring of the AuNPs. HR-TEM images exhibit that AuNPs (2.30 +/- 0.06 nm) are immobilized on the surface of ultrathin 2-dimensional TiO2NSs. AuNPs-TiO2NSs catalyst shows excellent catalytic activity towards the reduction of various NAs (4-NA, 4-NM and 4-FNM) and RhB dye with maximum conversion efficiency of >98 %. Moreover, the pseudo-first-order rate constants are estimated as 5.50 x 10- 3 s- 1, 7.20 x 10- 3 s- 1, 6.40 x 10-3 s- 1 and 4.30 x 10-3 s- 1 for the reduction of 4-NA, 4-NM, 4-FNM, and RhB, respectively. For large-scale in-dustrial applications, AuNPs-TiO2NSs catalyst embedded in a continuous flow-fixed bed reactor for the catalytic reduction of 4-NA and RhB dye under optimized reaction conditions. AuNPs-TiO2NSs catalyst shows high con-version rates for 4-NA (>99 %) and RhB (>99%) along with excellent recyclability over 12 cycles in continuous flow fixed bed reactor. The mechanism of synthetic pathway and catalytic reduction of NAs and RhB dye over AuNPs-TiO2NSs catalyst are also proposed. This study may lead to the use AuNPs-TiO2NSs catalyst with superior recyclable catalytic efficiency in various catalytic reactions.
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