Transitional dynamics from mercury to cyanide-based processing in artisanal and small-scale gold mining: Social, economic, geochemical, and environmental considerations.

Artisanal and small-scale gold mining (ASGM) is the leading global source of anthropogenic mercury (Hg) release to the environment. Top-down mercury reduction efforts have had limited results, but a bottom-up embrace of cyanide (CN) processing could eventually displace mercury amalgamation for gold recovery. However, ASGM transitions to cyanidation nearly always include an overlap phase, with mercury amalgamation then cyanidation being used sequentially. This paper uses a transdisciplinary approach that combines natural and social sciences to develop a holistic picture of why mercury and cyanide converge in gold processing and potential impacts that may be worse than either practice in isolation. We show that socio-economic factors drive the comingling of mercury and cyanide practices in ASGM as much or more so than technical factors. The resultant Hg-CN complexes have been implicated in increasing the mobility of mercury, compared to elemental mercury used in Hg-only processing. To support future inquiry, we identify key knowledge gaps including the role of Hg-CN complexes in mercury oxidation, transport, and fate, and possible links to mercury methylation. The global extent and increase of mercury and cyanide processing in ASGM underscores the importance of further research. The immediacy of the problem also demands interim policy responses while research advances, though ultimately, the well-documented struggles of mercury reduction efforts in ASGM temper optimism about policy responses to the mercury-cyanide transition.

Perceptions and realities of mercury contamination in a Peruvian artisanal and small-scale gold mining (ASGM) community.

Artisanal and small-scale gold mining (ASGM) is the leading global source of mercury pollution. Efforts to reduce or eliminate mercury use in ASGM have produced limited results, in part because they do not engage the complex socio-technical nature of mercury issues in ASGM. The paper takes a multidisciplinary approach to understand the mercury issue with a socio-technical lens, pairing sampling of mercury in soils with surveys of miners' and residents' perceptions of mercury pollution and its dispersion. The research was conducted in Secocha, an ASGM boomtown in southern Peru. Mercury levels in soils exceeded relevant standards in both industrial zones (average of 72.6 mg/kg, versus the Peruvian standard of 24 mg/kg) and residential/urban zones (average of 9.5 mg/kg, versus the Peruvian standard of 6.6 mg/kg). Mercury levels were highest where processing and gold buying activity were concentrated. Surveys revealed that miners and residents correctly assumed mercury pollution to be highest in those areas. However, respondents seemed to underestimate the extent of mercury pollution in other parts of town, and many believed that only those who handle mercury directly were affected by it. Respondents also placed low priority on reducing mercury pollution. Miners' and residents' partial knowledge about mercury contamination and the low priority accorded to the issue suggest that mercury reduction efforts would likely be met with indifference and potentially resistance.

Pandemic response in rural Peru: Multi-scale institutional analysis of the COVID-19 crisis.

The first wave of the COVID-19 pandemic was devastating in Peru, which suffered a high death rate and severe economic disruption. These results occurred despite ambitious response measures, revealing widespread institutional weaknesses across the country's levels of government. We analyze responses across the four levels of government, with emphasis on local governance in rural areas, to understand how institutions and contexts shape crisis management outcomes. We focus on the Arequipa region, drawing from 44 interviews with officials and community members. We found that the crisis provoked a reversion to the norm across multiple scales, though with significant differentiation. The national government fell back on a centralized, militarized approach that effectively reclaimed power but was ineffective in confronting the pandemic. Counter the overarching recentralization trend, in rural peripheries where state power was always partial, norms of informal local governance were reinforced and intensified. The de facto autonomy in rural areas elicited a mix of paralysis and improvisation, with outcomes that varied widely from place to place and over time. These bifurcated results in the face of crisis reveal important weaknesses in Peru's governance structures and institutions and show how pre-existing habits and norms were reproduced in the face of crisis, rather than reformed or transcended.

Association of prophage antiterminator Q alleles and susceptibility to food-processing treatments applied to Escherichia coli O157 in laboratory media.

Resistance of Escherichia coli O157 to inactivation by high-pressure processing, heat, and UV and gamma radiation was associated with the allele of the prophage-encoded antiterminator Q gene present upstream of the Shiga toxin gene stx2. Increased processing may be required to kill certain strains of E. coli O157, and the choice of strains used as surrogate markers for processing efficiency is critical.

Genes of Escherichia coli O157:H7 that are involved in high-pressure resistance.

Seventeen Escherichia coli O157:H7 strains were treated with ultrahigh pressure at 500 MPa and 23 +/- 2 degrees C for 1 min. This treatment inactivated 0.6 to 3.4 log CFU/ml, depending on the strain. The diversity of these strains was confirmed by pulsed-field gel electrophoresis (PFGE) analysis, and there was no apparent association between PFGE banding patterns and pressure resistance. The pressure-resistant strain E. coli O157:H7 EC-88 (0.6-log decrease) and the pressure-sensitive strain ATCC 35150 (3.4-log decrease) were treated with a sublethal pressure (100 MPa for 15 min at 23 +/- 2 degrees C) and subjected to DNA microarray analysis using an E. coli K-12 antisense gene chip. High pressure affected the transcription of many genes involved in a variety of intracellular mechanisms of EC-88, including the stress response, the thiol-disulfide redox system, Fe-S cluster assembly, and spontaneous mutation. Twenty-four E. coli isogenic pairs with mutations in the genes regulated by the pressure treatment were treated with lethal pressures at 400 MPa and 23 +/- 2 degrees C for 5 min. The barotolerance of the mutants relative to that of the wild-type strains helped to explain the results obtained by DNA microarray analysis. This study is the first report to demonstrate that the expression of Fe-S cluster assembly proteins and the fumarate nitrate reductase regulator decreases the resistance to pressure, while sigma factor (RpoE), lipoprotein (NlpI), thioredoxin (TrxA), thioredoxin reductase (TrxB), a trehalose synthesis protein (OtsA), and a DNA-binding protein (Dps) promote barotolerance.