Neurological and neuropsychological deterioration in artisanal gold miners from the town of Andacollo,Chile

It is widely known that human exposure to mercury vapor can cause neurological and neuropsychological deterioration. We have investigated if a population of Chilean artisanal gold-mining workers heavily exposed to elemental mercury (Hg⁰) display neurological and neuropsychological impairment. Male volunteers occupationally exposed to Hg⁰ (“gold miners”, n = 35) were recruited and compared with a group of unexposed workers (n = 40). Blood specimens were obtained from both groups for total mercury quantification. Upon neurological examination, 71% of the “gold miners” group showed abnormalities expressed as frontal impairment, tremor, or simultaneously frontal impairment, parkinsonism, and pyramidal syndrome. In contrast, only 16% of the individuals in the control group displayed neurological abnormalities. The “gold miners” group also showed impairment of the neuropsychological performance and the distribution of abnormal scores for almost all the neuropsychological tests applied was significantly higher in this group compared to the control group. Educational level, alcohol intake, and smoking habits did not influence the outcome of the neurological or neuropsychological examinations. Finally, despite that the higher blood mercury concentrations were found in the “gold miners” group, they were not significantly different from the values obtained in the control group.     

Changes in surface water quality from small-scale gold mining operations in the Surinamean rainforest

Abstract

Small-scale miners often engage in environmentally damaging activities, are subject to poor safety conditions, and utilize inefficient mineral extraction technologies. Here, we explore environmental impacts to surface waters from regional artisanal small-scale gold placer mining operations conducted in iron and aluminum-rich saprolites found within the lateritic, interior Amazon rainforest of Suriname. Heavy equipment was utilized to release gold from its host material followed by amalgamation and gravity separation. In contrast with background tributary recordings, streams adjacent to these gold mining operations consistently contained turbidity measurements that exceeded United States’ EPA guidelines for aquatic species of 50 nephelometric turbidity units and were typically in the hundreds to thousands of units. Turbidity was further heightened in association with precipitation events. Mercury played a prominent role in whole ore amalgam concentration practices. Freshwater fish from the region were found to harbor mercury that encroached upon public health criteria. Dissolved phase metals present further ecotoxicological challenges to the region, but their association with mining activities was less clear. These findings collectively reveal that small-scale placer gold mining practices in the Surinamese rainforest result in an increase of suspended sediments and release of mercury into waterways that could impact communities that depend upon local fisheries.     

Impact of Gold mining on the Environment and Human Health: A Case Study in the Migori Gold Belt, Kenya

The study of gold sites in the Migori Gold Belt, Kenya, revealed that the concentrations of heavy metals, mainly Hg, Pb and As are above acceptable levels. Tailings at the panning sites recorded values of 6.5–510 mg kg^–1 Pb, 0.06–76.0 mg kg^–1 As and 0.46–1920 mg kg^–1 Hg. Stream sediments had values of 3.0–11075 mg kg^–1 Pb, 0.014–1.87 mg kg^–1 As and 0.28–348 mg kg^–1 Hg. The highest metal contamination was recorded in sediments from the Macalder stream (11075 mg kg^–1 Pb), Nairobi mine tailings (76.0 mg kg^–1 As) and Mickey tailings (1920 mg kg^–1 Hg). Mercury has a long residence time in the environment and this makes its emissions from artisan mining a threat to health. Inhaling large amounts of siliceous dust, careless handling of mercury during gold panning and Au/Hg amalgam processing, existence of water logged pits and trenches; and large number of miners sharing poor quality air in the mines are the major causes of health hazards among miners. The amount of mercury used by miners for gold amalgamation during peak mining periods varies from 150 to 200 kg per month. Out of this, about 40% are lost during panning and 60% lost during heating Au/Hg amalgam. The use of pressure burners to weaken the reef is a deadly mining procedure as hot particles of Pb, As and other sulphide minerals burn the body. Burns become septic. This, apparently, leads to death within 2–3 years. On-site training of miners on safe mining practices met with enthusiasm and acceptance. The use of dust masks, air filters and heavy chemical gloves during mining and mineral processing were readily accepted. Miners were thus advised to purchase such protective gear, and to continue using them for the sake of their health. The miners' workshop, which was held at the end of the project is likely to bear fruit. The Migori District Commissioner and other Government officials, including medical officers attended this workshop. As a result of this, the Government is seriously considering setting up a clinic at Masara, which is one of the mining centres in the district. This would improve the health of the mining community.     

Vulnerability associated with “symptoms similar to those of mercury poisoning” in communities from Xingu River,Amazon basin

The Brazilian Amazon is known to be a region with high levels of mercury (Hg) in the environment and studies point to an association between high levels of natural mercury in the mother rock and the vast number of clandestine gold mines. Other studies already report the contamination of fish in this region, as well as high levels of Hg in biological material from environmentally exposed populations. On the other hand, this is one of the least developed regions of the planet and it is necessary to understand the vulnerability factors in these populations that may be intoxicated by this element. The purpose of the present study was to investigate the vulnerability factors in communities from Xingu River—Amazon basin probably exposed to Hg. A cross-selection study in two cities localized in Xingu River was conducted, and the sample contained was 268 individuals. sociodemographic questions, lifestyle, diet habits and health conditions were collated. The majority of the sample was female, between 30 and 59 years old, had less than 3 years of educational level and lived in the local of study more than 240 months. There was regular fish consumption (95.9%), principally carnivorous species (80.5%). The visual problem has a highest prevalence (43.3%) between the health problems and about the symptoms of Hg intoxication, memory loss (42.9%), weakness (35.1%), fatigue (34.3%), mood changes (28.7%) and difficulties in concentration (27.2%) was most reported. The female sex, age over 60, educational level below 3 years of study, did not had flush toilet, smoke and least one chronic non-communicable disease represent higher probability to had symptoms of Hg intoxication. Lack of access to health services, low education level and income evidence the susceptibility of this community to diseases and injuries. The vulnerable groups identified in this study should be a priority in public health and environmental health policies.     

The impact of artisanal gold mining,ore processing and mineralization on water quality in Marmato,Colombia

Marmato, Colombia, has been an important centre of gold mining since before the first Spanish colonizers arrived in 1536. The Marmato deposit is hosted in a dacite and andesite porphyry stock as sheeted sulphide-rich veinlet systems. The district is currently experiencing a surge in both major mining projects and artisanal mining, driven by sustained high gold prices. Ore from small-scale and artisanal gold mining is processed in numerous small mills (entables) around Marmato, which impact surface water quality through the discharge of milled waste rock slurry, highly alkaline cyanide-treated effluent, and high dissolved metal loads. To investigate the impact of artisanal mining and ore processing, water samples were collected in January 2012 from streams around Marmato. The average dissolved metal concentrations in impacted streams were Zn, 78 mg L^?1; Pb, 0.43 mg L^?1; Cu, 403 µg L^?1 Cd, 255 µg L^?1; As, 235 µg L^?1; Ni, 67 µg L^?1; Co, 55 µg L^?1; Sb, 7 µg L^?1; and Hg, 42 ng L^?1, exceeding World Health Organization drinking water guidelines. In addition, arsenic speciation was conducted in-situ and indicated that 91–95% of inorganic arsenic species is in the form of As(V). Spatial analysis of the data suggests that entables processing ore for artisanal miners are the main contributor to water pollution, with high sediment loads, alkalinity and elevated concentrations of dissolved arsenic, cadmium, mercury and lead, caused by the processing of gold-bearing sulphides in the entables. Geochemical data from surface water were compared to a comprehensive data set of whole rock analyses from drill core and channel samples from the deposit, indicating that the deposit is significantly enriched in gold, silver, lead, zinc, arsenic, antimony, and cadmium compared to crustal averages, which is reflected in the surface water geochemistry. However, elevated mercury levels in surface water cannot be explained by enrichment of mercury in the deposit and strongly suggest that mercury is being added to concentrates during ore processing to amalgamate fine gold.

     

Graduated stringency within collective incentives for group environmental compliance: Building coordination in field-lab experiments with artisanal gold miners in Colombia

Small-scale gold mining is important to rural livelihoods in the developing world but also a source of environmental externalities. Incentives for individual producers are the classic policy response for a socially efficient balance between livelihoods and the environment. Yet monitoring individual miners is ineffective, or it is very costly, especially on frontiers with scattered small-scale miners. We ask whether monitoring at a group level effectively incentivizes cleaner artisanal mining by combining lower-cost external monitoring with local collective action. We employ a mining-framed, threshold-public-goods experiment in Colombia's Pacific region, with 640 participants from frontier mining communities. To study compliance with collective environmental targets, we vary the target stringency, including to compare increases over time in the stringency versus decreases. We find that collective incentives can induce efficient equilibria, with group compliance – and even inefficient overcompliance – despite the existence of equilibria with zero contributions. Yet, for demanding targets in which the reward for compliance barely outweighs the cost, compliance can collapse. Those outcomes improve with past successes for easier targets, however, so our results suggest gain from building coordination via graduated stringency.     

Great tits breeding performance and mercury contamination from the paper and pulp industry in the west coast of Portugal

Passerine species have been increasingly used as monitors of metal pollution, especially by making use of non-destructive indicators of bird exposure, such as collecting feathers, faeces or blood. During this study, mercury concentrations were determined in feathers, faeces and blood of nestling great tits (Parus major) in industrial (a paper mill) and rural sites on the west coast of Portugal. The aim of this study was to compare the level of mercury in both areas over the study period, as indicated by nestlings’ mercury levels, while assessing possible contamination effects on the breeding performance and health status of great tits. Over the years, feathers showed a significant annual decrease in mercury contamination in the study area. Blood analyses also revealed a significant annual decrease in mercury concentrations, but no significant differences were detected between areas. Faeces data showed no significant difference between years or areas. We found no direct influence of mercury levels on nestling health status or great tit breeding performance.     

Serum Iron Concentrations, Lipid Peroxidation and Superoxide Dismutase Activity in Turkish Iron Miners

The effects of iron exposure, on serum iron, serum superoxide dismutase (SOD), a free radical scavenger, and plasma malondialdehyde (MDA), a lipid peroxidation parameter, were investigated in Turkish iron miners, office workers and healthy control subjects. Serum iron levels in both miner and office workers groups were higher than those of healthy controls (p < 0.05). There were higher mean values of plasma MDA levels in both iron miners and office workers compared to controls (p < 0.05). Serum SOD activity in the miner group was lower than that of controls (p < 0.05). These results suggested that elevated MDA levels in both miners and office workers were the result of an increased production and/or decreased catabolism of MDA in chronic iron exposure. These changes in MDA metabolism may be due to iron-induced lipid peroxidation in the blood and related body compartments.     

Seasonal distribution and speciation of mercury in a gold mining area,north-west province,South Africa

The seasonal speciation of mercury (Hg) was determined in water, soil, and sediments from watersheds located in the North-West province of South Africa. The study area is known to have a long history of mining activities which also include the recovery of gold from old tailings. Both inorganic (IHg) and methyl mercury (MHg) were detected at high concentrations (up to 8480 μg IHg kg^?1 and 13 μg MHg kg^?1) in surface sediments during dry season. A considerable remobilization of Hg from bottom sediments was observed in water from dry to wet season as well as the migration of Hg away from pollution sources due to seasonal influences. Hg in sediments mostly has been speciated as Hg⁰. Enhancement of Hg methylation occurred mainly in deeper sediments at regions corresponding to the lowest redox potential, higher pH, and enrichment of IHg. Hg values in borehole waters were very high (up to 3310 ng L^?1) suggesting a serious contamination of the site groundwater which needs to be addressed urgently in order to minimize further impact that affects the Vaal River and other water systems located nearby.     

Environmental contamination and risk assessment of mercury from a historic mercury mine located in southwestern China

A field survey of mercury pollution in environmental media and human hair samples obtained from residents living in the area surrounding the Chatian mercury mine (CMM) of southwestern China was conducted to evaluate the health risks of mercury to local residents. The results showed that mine waste, and tailings in particular, contained high levels of mercury and that the maximum mercury concentration was 88.50 μg g^?1. Elevated mercury levels were also found in local surface water, paddy soil, and paddy grain, which may cause severe health problems. The mercury concentration of hair samples from the inhabitants of the CMM exceeded 1.0 μg g^?1, which is the limit recommended by the US EPA. Mercury concentrations in paddy soil were positively correlated with mercury concentrations in paddy roots, stalks, and paddy grains, which suggested that paddy soil was the major source of mercury in paddy plant tissue. The average daily dose (ADD) of mercury for local adults and preschool children via oral exposure reached 0.241 and 0.624 μg kg^?1 body weight per day, respectively, which is approaching or exceeds the provisional tolerable daily intake. Among the three oral exposure routes, the greatest contributor to the ADD of mercury was the ingestion of rice grain. Open-stacked mine tailings have resulted in heavy mercury contamination in the surrounding soil, and the depth of appreciable soil mercury concentrations exceeded 100 cm.     

Mercury Contamination of Fish and Its Implications for Other Wildlife of the Tapajós Basin, Brazilian Amazon

Abstract: Since 1979 the gold rush in the Brazilian Amazon has caused serious environmental damage to one of the most complex ecosystems on Earth. Mainly due to the toxicity of mercury to humans, this problem has received wide public attention and prompted many studies. Although these studies have involved sampling of fish, the negative effect of mercury contamination to fish themselves and other wildlife has been largely ignored. To assess the present level of mercury contamination of fish, and its implication for fish and other animals, we collected and examined data on mercury concentration in fish of the Brazilian Amazon, especially for the Tapajós basin, between 1991 and 1996. We conclude that omnivores and piscivores that live nearer to gold mining areas in the Tapajós basin are already at high risk of mercury toxification, especially reproductive failure. Mercury concentrations in these fish are also high enough to have detrimental effects on animals at higher trophic levels. The same conclusion applies to other mercury-contaminated areas in the Brazilian Amazon. Because most Amazonian rivers or their tributaries have favorable conditions for mercury contamination, we can expect the problem to persist in the Amazon for a long time, and the consequences are likely to become more significant in the future. These conclusions have important implications for all tropical rainforests where gold mining operations have caused extensive mercury pollution.     

Mercury pollution in the Sonbhadra district of Uttar Pradesh,India, and its health impacts

The Sonbhadra district in the Singrauli area of Uttar Pradesh, India, has many coal mines and thermal power plants and is a critically polluted area. Many residents of this area reported adverse health conditions which may be linked to metal pollution, especially of mercury investigated here.

In May 2012, samples of water (23), soil (7), blood, hair, and nails from persons showing adverse health conditions selected at random were collected and analyzed for total mercury by atomic absorption spectrometry.

Twenty percent drinking water samples contained mercury from 3 to 26 μg L^?1 (3–26 times the permissible limit). Soil samples had 0.5–10.1 mg kg^?1 Hg.

The average concentrations of mercury in human blood, hair, and nails were found to be 34 μg L^?1, 7.4 mg kg^?1, and 0.8 mg kg^?1, respectively. Mercury concentrations in the blood of these persons were 45 and 28 μg L^?1 on average in the case of men and women. This is much higher than the safe level of 5.8 μg L^?1 set by the United States Environmental Protection Agency (USEPA).

It was concluded that all residents of Sonbhadra sampled could be suffering from mercury toxicity as the area is polluted by Hg released from the coal-fired thermal power plants.     

北京地区大气中汞污染状况的初步调查

用镀金细砂填充的石英采样管在采暖期的非采暖期于北京地区七个采样点收集空气中的气态汞,用二步汞齐化原子吸收法测定其浓度并与实时分析结果进行比较,两种方法的结果都表明,采暖期北京地区大气中汞的浓度低于非采暖期大气中汞的浓度,对于除燃煤以外汞的来源尚需进一步研究。     

A compilation of field surveys on gaseous elemental mercury (GEM) from contrasting environmental settings in Europe,South America,South Africa and China: separating fads from facts

Mercury is transported globally in the atmosphere mostly in gaseous elemental form (GEM, \( {\text{Hg}}_{\text{gas}}^{0} \) ), but still few worldwide studies taking into account different and contrasted environmental settings are available in a single publication. This work presents and discusses data from Argentina, Bolivia, Bosnia and Herzegovina, Brazil, Chile, China, Croatia, Finland, Italy, Russia, South Africa, Spain, Slovenia and Venezuela. We classified the information in four groups: (1) mining districts where this contaminant poses or has posed a risk for human populations and/or ecosystems; (2) cities, where the concentration of atmospheric mercury could be higher than normal due to the burning of fossil fuels and industrial activities; (3) areas with natural emissions from volcanoes; and (4) pristine areas where no anthropogenic influence was apparent. All the surveys were performed using portable LUMEX RA-915 series atomic absorption spectrometers. The results for cities fall within a low GEM concentration range that rarely exceeds 30 ng m^?3, that is, 6.6 times lower than the restrictive ATSDR threshold (200 ng m^?3) for chronic exposure to this pollutant. We also observed this behavior in the former mercury mining districts, where few data were above 200 ng m^?3. We noted that high concentrations of GEM are localized phenomena that fade away in short distances. However, this does not imply that they do not pose a risk for those working in close proximity to the source. This is the case of the artisanal gold miners that heat the Au–Hg amalgam to vaporize mercury. In this respect, while GEM can be truly regarded as a hazard, because of possible physical–chemical transformations into other species, it is only under these localized conditions, implying exposure to high GEM concentrations, which it becomes a direct risk for humans.     

Reagenzienfreie Bestimmung von Quecksilberspuren in Wasserproben

A comprehensive ecological monitoring of hazardous substances is indispensable to preserve our health and environment. Therefore, fast and inexpensive techniques for routine analysis of pollutants are essential. However, in the measuring procedure itself often toxic reagents are used producing hazardous waste. Omitting environmentally hazardous substances in the analysis procedure is an important contribution to a more sustainable and green analytical chemistry. A reagent-free method for ultra-trace (pg to ng?L^-1) mercury determination in water samples was developed and validated. An active nanogold collector integrated in a fully automated flow injection system is the core of this new method. All mercury species dissolved in the water sample are adsorbed and preconcentrated on the nano-structured gold surface of the collector. After rinsing and drying of the collector, the enriched mercury is thermally desorbed and finally measured by atomic fluorescence spectrometry. This method was optimized and validated for the determination of mercury in natural waters. The influence of various water constituents was investigated and only high contents of dissolved organic carbon (DOC) showed interferences of mercury preconcentration due to the strong complexation of mercury by DOC. This restriction can be solved by UV-irradiation, i.?e. reagent-free digestion of DOC rich samples prior to the preconcentration procedure. Mercury concentration of several natural river and sea waters and water from the discharge of a waste water treatment plant were determined with this new analytical method. Accuracy and precision of the method were demonstrated by several recovery experiments in natural water samples (recoveries: 96–102?%) and by analysis of the certified reference material BCR-579 (Mercury in Coastal Sea Water; recovery: 101?±?1?%). With a detection limit of only 80?pg?Hg?L^–1 the proposed method is highly sensitive. Furthermore the method avoids potential contamination of the sample by reagent addition and is due to the reagent-free procedure environment-friendly. Hence this work is an important contribution to sustainable environmental analysis and at the same time improves accurate routine mercury trace analysis.     

铝对荞麦和金荞麦根际土壤微生物及酶活性的影响

以两种耐锅性不同蓼科荞麦属植物荞麦和金荞麦为材料,通过土培盆栽试验,比较研究其根际土壤微生态对铝胁迫反应的差异.结果表明,一定质量分数的Al对荞麦和金荞麦根际土壤绌菌具有显著刺激效应,对金荞麦的影响更大,但Al质量分数过高,对细菌的刺激效应明显减弱,甚至产生抑制作用,荞麦和金荞麦根际土壤真菌数量均随着Al质量分数的升高而明显增加,荞麦根际土壤真菌增加幅度更为显著,Al胁迫下二者根际放线菌数量的变化亦表现出一定的差异;Al胁迫下,养麦和金荞麦根际土壤氨化细菌、硝化绌菌、反硝化细菌等氮素生理群微生物的变化趋势亦显示出明显差异,整体上荞麦根际土壤细菌生珲群对Al胁迫比金荞麦更敏感;Al胁迫对荞麦和金荞麦根际土壤过氧化氢酶活性均表现出较弱的抑制效应,但荞麦根际土壤始终维持较金荞麦更高的过氧化氢酶活性,这与荞麦具有更强的耐铝性有一定的关系,荞麦和金荞麦根际土壤转化酶对Al非常敏感,随着铝的加入,其活性显著下降,荞麦和金荞麦根际土壤脲酶活性的变化趋势基本一致,但整体上荞麦根际土壤脲酶活性均明显低于金荞麦,这是否与其耐铝毒特性的差异有关有待于进一步探讨.     

Catalytic decomposition of low level ozone with gold nanoparticles supported on activated carbon

Highly dispersed gold nanoparticles were supported on coal-based activated carbon (AC) by a sol immobilization method and were used to investigate their catalytic activity for low-level ozone decomposition at ambient temperature. Nitrogen adsorption-desorption, scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS) were used to characterize the catalysts before and after ozone decomposition. The results showed that the supported gold nanoparticles prepared with microwave heating were much smaller and more uniformly dispersed on the activated carbon than those prepared with traditional conduction heating, exhibiting higher catalytic activity for ozone decomposition. The pH values of gold precursor solution significantly influenced the catalytic activity of supported gold for ozone decomposition, and the best pH value was 8. In the case of space velocity of 120000h⁻¹, inlet ozone concentration of 50mg/m³, and relative humidity of 45%, the Au/AC catalyst maintained the ozone removal ratio at 90.7% after 2500min. After being used for ozone decomposition, the surface carbon of the catalyst was partly oxidized and the oxygen content increased accordingly, while its specific surface area and pore volume only decreased a little. Ozone was mainly catalytically decomposed by the gold nanoparticles supported on the activated carbon.     

邻苯二甲酸二乙基己酯（DEHP）对金鲫鱼脑细胞DNA的损伤

为了研究邻苯二甲酸二乙基己酯(DEHP)对金鲫鱼(Carassius auratu)脑细胞DNA的损伤作用,采用不同浓度的DEHP溶液(0、25、50、100、200mg·L-1)对体外培养脑细胞进行染毒,应用单细胞凝胶电泳(彗星实验)检测脑细胞DNA的损伤效应.结果表明,染毒1.5h后,与对照组相比,DEHP各染毒组细胞尾部DNA百分率(Tail DNA%)和尾矩(Tail Moment)均显著升高(p<0.01),即DEHP染毒引起了脑细胞DNA的严重断裂;随着DEHP浓度的增加,DNA损伤程度加剧,细胞尾部DNA百分率及尾距与DEHP染毒浓度呈明显的剂量-效应关系.以上结果表明,DEHP可导致金鲫鱼脑细胞DNA损伤。     

Mercury contamination in selected foodstuffs and potential health risk assessment along the artisanal gold mining,Gilgit-Baltistan,Pakistan

This study investigates the mercury (Hg) contaminations in soil and foodstuffs along the artisanal gold mining areas, Gilgit-Baltistan Province, Pakistan. For this purpose, soils were analyzed for Hg concentrations and evaluated for the enrichment/contamination using enrichment factor or contamination factors (CF). The CF values ranged from 18.9 to 153 showed multifold higher levels of Hg contamination as compared to background or reference site. Foodstuffs including vegetables, seeds or grains and fish muscles showed Hg accumulation. Results revealed that Hg concentrations in foodstuffs were higher than the critical human health value set by European Union. The Hg in foodstuffs was consumed and, therefore, evaluated for the risk assessment indices using the daily intake (DI) and health risk index (HRI) for the exposed human population both children and adults. Results of this study revealed that cumulative HRI values through foodstuffs consumption were <1 (within safe limit), but if the current practices continued, then the Hg contamination could pose potential threat to exposed population in near future.     

Preliminary study on health risk from mercury exposure to residents of Wujiazhan town on the Di’er Songhua river, Northeast China

Mercury concentrations in hair are typically used as a biomarker to assess exposure to mercury. A total of 108 hair samples were collected from residents (age range 5–73 years) of Wujiazhan town, northeast China, to determine total mercury concentrations. Hair mercury concentrations ranged from 0.16 to 199 mg kg^–1 with an average value of 3.41 mg kg⁻¹. The relationships between mercury concentration and gender and between hair mercury concentration and age were not significant. Overall, 16.7% of all samples were above the RfD value published by the United States Environmental Protection agency. The results indicate that there may be some been health risk from mercury exposure to the residents in the study area.