Mercury pollution from the artisanal gold mining in the La Paz department, Bolivia

Pòster amb el resum gràfic de la tesi doctoral en curs, que forma part de l'exposició "Doctorat en Recursos Naturals i Medi Ambient de la UPC Manresa. 30 anys formant en recerca a la Catalunya Central 1992-2022".Research supported by the project AECID: A3/042750/11 and CCD 2019-B005, 2020-B006, 2021-G007 and 2022-B009.Postprint (published version

The use of mercury for gold recovering in the artisanal gold mining from the Mapiri river basin, Apolobamba, Bolivia

Peer ReviewedPostprint (published version

Environmental pollution produced by gold artisanal mining in the Mapiri river basin, Apolobamba, Bolivia

Mining activity is very important in Bolivia since colonial times. Today it has been reactivated, especially gold mining, due to rise in metal prices. Artisanal and small-scale mining activities are abundant in the protected area of Apolobamba, near the border with Peru. Here mercury is used to recovery gold by obtaining an Hg-Au amalgam. This manipulation with mercury causes an important environmental impact in the area. The present work is a preliminary study of the contamination of the Mapiri river basin in the Apolobamba area. In the head of this basin, located at more than 4000 m above sea level, gold is mined from hydrothermal gold deposits of Paleozoic age. We have sampled several mining sites from this area, in particular the ones known as Viscachani, Flor de Mayo and Chojlaya, located in the proximity of the head area of the Mapiri river basin. These mining sites were in activity during the present sampling campaign. Different metals were measured by means of XRF (Se, As, Cu, Zn, Cd, Pb, Hg) in tailing samples from the different gold mining sites. In addition mercury concentrations were measured in water and in vegetation close to the processing areas by means of atomic absorption spectrometry with Zeeman effect (LUMEX RA-915 Equipment). Tailings are mainly constituted by quartz with minor contents of clay minerals and sulphides. The most abundant sulphides are galena and arsenopyrite. Chalcopyrite, sphalerite, pyrite and sulphosalts also occur in minor amounts, as well as minor secondary minerals. Gold content, after recovery with mercury, is high, between 4.56 ppm and 10.35 ppm. The Hg content of the tailings ranges from 149 to 1027 ppm. Lixiviable mercury from these samples ranges between 30.10 and 859.94 ng l-1. Water released from the tailings contains between 0.1 and 5.7 ppb of Hg. Studied vegetation typical of the area has high Hg contents, between 162 and 219 ppm. In addition there is a high arsenic content in all the studied tailings, except in those from the Viscachani mining site, where concentrations of this element ranges from 456 ppm to 18540 ppm. The Pb content usually ranges from 337 to 939 ppm. The Chojlaya mining site tailing has exceptionally high values of heavy metals: Pb content is between 2.26 and 3.27 wt.%, Cd ranges from 160 to 228 ppm, Zn from 194 to 794 ppm, Cu from 847 to 1052 ppm and Se from 105 to 187 ppm. These contents also contribute to an environmental pollution. In conclusion the gold mining activities in the Mapiri river basin produce and intense environmental pollution, mainly related to mercury and arsenic contents in the proximity of these mining activities. After processing, tailings still contain important amounts of gold suggesting that the amalgamation method is not effective to gold recovering.Peer ReviewedPostprint (published version

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Environmental pollution produced by gold artisanal mining in the Mapiri river basin, Apolobamba, Bolivia

Mining activity is very important in Bolivia since colonial times. Today it has been reactivated, especially gold mining, due to rise in metal prices. Artisanal and small-scale mining activities are abundant in the protected area of Apolobamba, near the border with Peru. Here mercury is used to recovery gold by obtaining an Hg-Au amalgam. This manipulation with mercury causes an important environmental impact in the area. The present work is a preliminary study of the contamination of the Mapiri river basin in the Apolobamba area. In the head of this basin, located at more than 4000 m above sea level, gold is mined from hydrothermal gold deposits of Paleozoic age. We have sampled several mining sites from this area, in particular the ones known as Viscachani, Flor de Mayo and Chojlaya, located in the proximity of the head area of the Mapiri river basin. These mining sites were in activity during the present sampling campaign. Different metals were measured by means of XRF (Se, As, Cu, Zn, Cd, Pb, Hg) in tailing samples from the different gold mining sites. In addition mercury concentrations were measured in water and in vegetation close to the processing areas by means of atomic absorption spectrometry with Zeeman effect (LUMEX RA-915 Equipment). Tailings are mainly constituted by quartz with minor contents of clay minerals and sulphides. The most abundant sulphides are galena and arsenopyrite. Chalcopyrite, sphalerite, pyrite and sulphosalts also occur in minor amounts, as well as minor secondary minerals. Gold content, after recovery with mercury, is high, between 4.56 ppm and 10.35 ppm. The Hg content of the tailings ranges from 149 to 1027 ppm. Lixiviable mercury from these samples ranges between 30.10 and 859.94 ng l-1. Water released from the tailings contains between 0.1 and 5.7 ppb of Hg. Studied vegetation typical of the area has high Hg contents, between 162 and 219 ppm. In addition there is a high arsenic content in all the studied tailings, except in those from the Viscachani mining site, where concentrations of this element ranges from 456 ppm to 18540 ppm. The Pb content usually ranges from 337 to 939 ppm. The Chojlaya mining site tailing has exceptionally high values of heavy metals: Pb content is between 2.26 and 3.27 wt.%, Cd ranges from 160 to 228 ppm, Zn from 194 to 794 ppm, Cu from 847 to 1052 ppm and Se from 105 to 187 ppm. These contents also contribute to an environmental pollution. In conclusion the gold mining activities in the Mapiri river basin produce and intense environmental pollution, mainly related to mercury and arsenic contents in the proximity of these mining activities. After processing, tailings still contain important amounts of gold suggesting that the amalgamation method is not effective to gold recovering.Peer Reviewe

The use of mercury for gold recovering in the artisanal gold mining from the Mapiri river basin, Apolobamba, Bolivia

Peer Reviewe

Environmental pollution produced by gold artisanal mining in the Mapiri river basin, Apolobamba, Bolivia

Mining activity is very important in Bolivia since colonial times. Today it has been reactivated, especially gold mining, due to rise in metal prices. Artisanal and small-scale mining activities are abundant in the protected area of Apolobamba, near the border with Peru. Here mercury is used to recovery gold by obtaining an Hg-Au amalgam.This manipulation with mercury causes an important environmental impact in the area.The present work is a preliminary study of the contamination of the Mapiri river basin in the Apolobamba area.In the head of this basin, located at more than 4000 m above sea level, gold is mined from hydrothermal golddeposits of Paleozoic age. We have sampled several mining sites from this area, in particular the ones known asViscachani, Flor de Mayo and Chojlaya, located in the proximity of the head area of the Mapiri river basin. These mining sites were in activity during the present sampling campaign.Different metals were measured by means of XRF (Se, As, Cu, Zn, Cd, Pb, Hg) in tailing samples from the different gold mining sites. In addition mercury concentrations were measured in water and in vegetation closeto the processing areas by means of atomic absorption spectrometry with Zeeman effect (LUMEX RA-915 Equipment).Tailings are mainly constituted by quartz with minor contents of clay minerals and sulphides. The most abundant sulphides are galena and arsenopyrite. Chalcopyrite, sphalerite, pyrite and sulphosalts also occur in minoramounts, as well as minor secondary minerals. Gold content, after recovery with mercury, is high, between 4.56 ppm and 10.35 ppm.The Hg content of the tailings ranges from 149 to 1027 ppm. Lixiviable mercury from these samples ranges between 30.10 and 859.94 ng l-1. Water released from the tailings contains between 0.1 and 5.7 ppb of Hg.Studied vegetation typical of the area has high Hg contents, between 162 and 219 ppm.In addition there is a high arsenic content in all the studied tailings, except in those from the Viscachani mining site, where concentrations of this element ranges from 456 ppm to 18540 ppm. The Pb content usually ranges from 337 to 939 ppm. The Chojlaya mining site tailing has exceptionally high values of heavy metals: Pb content is between 2.26 and 3.27 wt.%, Cd ranges from 160 to 228 ppm, Zn from 194 to 794 ppm, Cu from 847 to 1052 ppm and Se from 105 to 187 ppm. These contents also contribute to an environmental pollution.In conclusion the gold mining activities in the Mapiri river basin produce and intense environmental pollution, mainly related to mercury and arsenic contents in the proximity of these mining activities. After processing,tailings still contain important amounts of gold suggesting that the amalgamation method is not effective to gold recovering.Peer Reviewe

The use of mercury for gold recovering in the artisanal gold mining from the Mapiri river basin, Apolobamba, Bolivia

Peer Reviewe

Mercury pollution from the artisanal mining in Yani gold district, Northern Bolivia

Artisanal gold mining is the main economic activity in the Yani district, Northern Bolivia. In this area abundant orogenic gold deposits constituted by quartz veins hosted in paleozoic turbiditic series that contain either free gold or associated with pyrite. Gold is recovered in processing plants by gravimetric methods using shaking tables in several communities of this district. Previously, miners ground the mineral in ball mills together with mercury. The present study aims to evaluate the effect of mercury used in the gold recovering process to the environment and human health in the Yani district. The assessment was based on the analysis of human hair, sediments and water from the river nearby the processing plant and drinking water from the fountain that supplies these communities. 47 samples of hair from miners and other people from the Yani and Señor de Mayo communities were obtained in 2014 and 52 samples in 2015. All were analysed to evaluate the mercury exposure in these places. The results from the 2014 sampling show a wide range of Hg concentration in hair, especially in Señor de Mayo, with values up to 136 µg/g THg. However, in 2015 among the 43 residents in Señor de Mayo, 29 (67%) exhibit concentrations higher than 2 µg/g THg, with an average value of 5.36 µg/g THg. On the other hand, in Yani only 40% have concentrations above 2 µg/g THg, with an average value of 2.34 µg/g THg. The content in Hg in most of the hair samples exhibit values above the tolerable limits established by the US Environmental Protection Agency (1 µg/g Hg) and the World Health Organisation (WHO, 2 µg/g Hg). These high Hg concentrations are found not only in miners but also in the other members of the community, in spite of low fish consumption in this area. Part of the hair was analysed before and after cleaning. Usually in the second case the content of Hg is reduced, but still show high Hg levels, then probably the atmosphere is polluted with Hg and population is exposed to Hg vapour. The average of Hg contents in hair from Señor de Mayo is double than in Yani. This can be explained because in the former the processing plant is located much closer to the community. The THg concentration in water from the river vary from 0.12 to 0.22 µg/g THg and from the drinking water display values around 0.22 µg/g THg, both below the tolerable limits indicated by the WHO. THg levels in sediments collected in river near the processing plant of Señor de Mayo and Yani show high Hg concentrations, 2.4 and 5.9 µg/g, respectively, which represent a serious environmental risk. Most of the obtained values of mercury concentration in hair indicate a high level of pollution. The miners of these areas should find out alternative methods for gold recovery.Peer ReviewedPostprint (published version

Mercury pollution from the artisanal mining in Yani gold district, Northern Bolivia

Artisanal gold mining is the main economic activity in the Yani district, Northern Bolivia. In this area abundant orogenic gold deposits constituted by quartz veins hosted in paleozoic turbiditic series that contain either free gold or associated with pyrite. Gold is recovered in processing plants by gravimetric methods using shaking tables in several communities of this district. Previously, miners ground the mineral in ball mills together with mercury. The present study aims to evaluate the effect of mercury used in the gold recovering process to the environment and human health in the Yani district. The assessment was based on the analysis of human hair, sediments and water from the river nearby the processing plant and drinking water from the fountain that supplies these communities. 47 samples of hair from miners and other people from the Yani and Señor de Mayo communities were obtained in 2014 and 52 samples in 2015. All were analysed to evaluate the mercury exposure in these places. The results from the 2014 sampling show a wide range of Hg concentration in hair, especially in Señor de Mayo, with values up to 136 µg/g THg. However, in 2015 among the 43 residents in Señor de Mayo, 29 (67%) exhibit concentrations higher than 2 µg/g THg, with an average value of 5.36 µg/g THg. On the other hand, in Yani only 40% have concentrations above 2 µg/g THg, with an average value of 2.34 µg/g THg. The content in Hg in most of the hair samples exhibit values above the tolerable limits established by the US Environmental Protection Agency (1 µg/g Hg) and the World Health Organisation (WHO, 2 µg/g Hg). These high Hg concentrations are found not only in miners but also in the other members of the community, in spite of low fish consumption in this area. Part of the hair was analysed before and after cleaning. Usually in the second case the content of Hg is reduced, but still show high Hg levels, then probably the atmosphere is polluted with Hg and population is exposed to Hg vapour. The average of Hg contents in hair from Señor de Mayo is double than in Yani. This can be explained because in the former the processing plant is located much closer to the community. The THg concentration in water from the river vary from 0.12 to 0.22 µg/g THg and from the drinking water display values around 0.22 µg/g THg, both below the tolerable limits indicated by the WHO. THg levels in sediments collected in river near the processing plant of Señor de Mayo and Yani show high Hg concentrations, 2.4 and 5.9 µg/g, respectively, which represent a serious environmental risk. Most of the obtained values of mercury concentration in hair indicate a high level of pollution. The miners of these areas should find out alternative methods for gold recovery.Peer Reviewe