artisanal gold mining in madre de dio, peru:
ANNOTATED BIBLIOGRPAHY OF PEER-REVIEWED ARTICLES
HUMAN EXPOSURE TO MERCURY THROUGH ASGM IN PERU
Ashe K. 2012. Elevated mercury concentrations in humans of Madre de Dios, Peru. PLoS ONE. 7(3): 1-6.
This paper reports elevated hair mercury concentrations in people near mining communities (11% of the population) compared to the non-mining community of Puerto Maldonado (5% of the population). The main predictor of mercury concentration in people was fish consumption; of those eating more than 12 fish meals per month, 18% had elevated mercury concentrations compared to 7% of the population with elevated mercury concentrations among those eating 6-11 fish meals per month. Fish consumption patterns were not related to age, gender, or location. Additionally, hair mercury concentration was associated with gender, with males displaying higher concentrations than women; in mining areas, males had an average of 3.39 ug/g merucry compared to women who had an average of 2.23 ug/g mercury. Hair mercury concentrations were not correlated with age or duration of residence in a location.
Fraser B. 2016. Peru's gold rush raises health fears. Nature. 534: 161.
This news release reports a Public Health Emergency established in Madre de Dios due to high mercury exposures in the region. The government of Peru estimates that 48,000 people across 85,301 square kilometers have been affected by high mercury exposure associated with ASGM. Researchers found that 40% of residents in Madre de Dios had hair mercury levels above the maximum level recommended by the World Health Organization. This led to the 60-day public-health emergency declared by the government on May 23, 2016. While the problem will not be solved quickly, the deputy health minister suggested that long-term plans should include the establishment of fish farms. However, some local officials remained unconvinced of the connection between human hair mercury concentration and fish consumption.
Fraser B. 2009. Peruvian gold rush threatens health and the environment. Environ. Sci. & Tech Persp. 43(19): 7612-7164.
This perspective article explains the role of mercury in ASGM and its associated consequences. Mining is popular because it provides the opportunity for miners to earn $100 in 24 hours, compared to the national minimum wage of $180 per month for unskilled workers. This practice, however, releases 32 t of mercury annually. As a result, the article cites research showing mercury levels in river water to be 3 to 25 times the Peruvian limit, while piscivorous fish also displayed elevated mercury concentrations. With high gold prices, the authors speculates that it is unlikely for mercury use to decrease, but incentives could be introduced to encourage mercury recovery; for example, the use of a mercury capture system decreased air mercury concentrations in a Puerto Maldonado shop from 450 ug/m3 to 40 ug/m3, still above the WHO's occupational standard of 20 ug/m3, but much lower than before the measure. Nevertheless, the article concludes that formalization and law enforcement are still necessary for miners to adapt these cleaner practices and reduce other ASGM impacts such as deforestation.
Gonzalez DJX. 2015. Mercury exposure and risk among women of childbearing age in Madre de Dios, Peru. Trop. Res. 34: 16-24.
This paper examines the risk factors associated with mercury exposure in women of childbearing age (18-49 years old) in Madre de Dios. Average mercury level in hair samples from 170 people in three cities was 1.97 ppm mercury (range: 0.01-8.11 ppm), nearly two times the World Health Organization reference limit of 1 ppm. Of the participants tested, 78% had mercury levels higher than 1 ppm. Mercury concentrations were particularly elevated near Iberia (a city outside of the mining zone), where people had an average of 2.37 ppm mercury in hair, though this average hair mercury concentration is lower than that of previous students conducted in Puerto Maldonado. Mercury concentration across the three cities was correlated with fish consumption. This paper also found that most people do not understand the health risks and symptoms associated with mercury exposure (only 26% had at least some knowledge), but were generally worried about this danger (73%).
Langeland AL, Hardin RD, and Neitzel RL. 2017. Mercury levels in human hair and farmed fish near artisanal and small-scale gold mining communities in the Madre de Dios River Basin, Peru. Int. J. of Environ. Res. Public Health. 14(3): 302.
This study compares hair mercury levels (n=80) across three ASGM-impacted communities (Bajo Madre de Dios, Boca Amigo, Mazuco) and one non-impacted community (Pilcopata) in Madre de Dios to the WHO’s Provisional Tolerable Weekly Intake of 2.2 µg/g in hair, and compares mercury levels of fish-farmed paco (n=111) to the EPA limit of 0.3µg/g. Total mercury in hair was found to be higher in mining communities (3.3, 4.5, and 1.9 ug/g, respectively) than the non-mining community (.8 ug/g) and was frequently above the WHO level (14%, 15%, and 6% compared to 1%). Hair mercury levels were not associated with gender or with mercury concentration in aquaculture fish. All paco sampled were below the USEPA criterion for mercury, though the fish were all half the age of those harvested for the market (6 months old compared to 1 year) and the ponds sampled were only a few years old.
Weinhouse C, Ortiz EJ, Berky AJ, Bullins P, Hare-Grogg J, Rogers L, Morales AM, Hsu-Kim H, and Pan WK. 2017. Hair mercury level is associated with anemia and micronutrient status in children living near artisanal and small-scale gold mining in the Peruvian Amazon. The Am. Jour. of Trop. Med. Hyg. 97(6): 1886-1897.
This study investigates the association between hair mercury concentration and anemia in Madre de Dios. It reports that 49% of children under 5 and 52% of children aged 5 to 11 were anemic, but few children were stunted (12%), wasted (2%) or underweight (5%), suggesting that anemia is not caused by malnutrition in this region. Median total hair mercury was 1.03 µg/g, with 22% of children under 12 above the USEPA guideline of 1.2 µg /g mercury in hair. Though the full sampled population showed no correlation between total hair mercury and hemoglobin levels, a subset of the population displayed an inverse relationship between hair mercury and hemoglobin, providing preliminary data that mercury exposure may be associated with anemia. The association between mercury and hemoglobin held with age, sex, BMI, and vitamin B12, but was not apparent when vitamin A was included in the model. Hair mercury was also associated with vitamin B12 and vitamin A, but not with zinc, folate, or vitamin D. Four potential pathways for methylmercury induced anemia are proposed in the study: methylmercury induces eryptosis due to excessive oxidative damage, methylmercury mimics or exacerbates vitamin B12 or folate deficiency, methylmercury dysregulates iron homeostasis, and methylmercury induces mitochondrial anemia.
This study investigates the association between hair mercury concentration and anemia in Madre de Dios. It reports that 49% of children under 5 and 52% of children aged 5 to 11 were anemic, but few children were stunted (12%), wasted (2%) or underweight (5%), suggesting that anemia is not caused by malnutrition in this region. Median total hair mercury was 1.03 µg/g, with 22% of children under 12 above the USEPA guideline of 1.2 µg /g mercury in hair. Though the full sampled population showed no correlation between total hair mercury and hemoglobin levels, a subset of the population displayed an inverse relationship between hair mercury and hemoglobin, providing preliminary data that mercury exposure may be associated with anemia. The association between mercury and hemoglobin held with age, sex, BMI, and vitamin B12, but was not apparent when vitamin A was included in the model. Hair mercury was also associated with vitamin B12 and vitamin A, but not with zinc, folate, or vitamin D. Four potential pathways for methylmercury induced anemia are proposed in the study: methylmercury induces eryptosis due to excessive oxidative damage, methylmercury mimics or exacerbates vitamin B12 or folate deficiency, methylmercury dysregulates iron homeostasis, and methylmercury induces mitochondrial anemia.
Wyatt L, Ortiz EJ, Feingold B, Berky A, Diringer S, Morales AM, Jurado ER, Hsu-Kim H, and Pan W. 2017. Spatial, temporal, and dietary variables associated with elevated mercury exposure in Peruvian riverine communities upstream and downstream of artisanal and small-scale gold mining. Int. J. Environ. Res. Public Health. 14: 1582.
This study examines hair mercury concentration (n=231) in twelve communities where ASGM has increased 4-6 fold over the past decade in comparison to concentrations of mercury in locally caught fish tissue. It evaluates general mercury exposure risks including fish and non-fish dietary items through household surveys and reports that calculations of oral reference dose using mercury content in fish underestimated observed mercury exposure (by 26%), especially in communities upstream of ASGM (by up to 48%). The study found that 86% of individuals and 77% of children exceeded the USEPA mercury provisional level of 1.2 µg/g. Adults had higher mercury concentration than children, but mercury did not differ by sex. Communities in or downstream of ASGM had the greatest prevalence of people exceeding 2.0 µg/g mercury (80% and 62%, respectively), though the highest average hair mercury concentration occurred in the upstream community of Boca Manu (4.8 µg/g). Despite having the highest hair mercury concentrations, previous studies at Boca Manu found low sediment and fish mercury concentrations. In general, fish did not correlate to hair mercury concentration, though consumption of high trophic level fish was correlated and led to a 57-168% increase in hair mercury. Hair mercury concentrations did not vary over time, with 63% of hair segments containing mercury concentrations within 20% of the most proximal 2-cm hair segment. Though average household hair mercury was negatively correlated with individual hair mercury (likely because males over 40 years had high mercury levels), children were 2-4 times more likely to exceed 1.2 µg/g if their mother exceeded this level than children whose mothers were below this level. Additionally, for children under 5 years of age, being underweight was associated with lower hair mercury concentrations, while over 80% of women of childbearing age had hair mercury concentration above 1.2 µg/g. The study also reports a 97% probability than an individual with mercury above 1.2 µg/g also had high mercury levels 8-10 months of the previous year. It also finds that hair mercury concentrations were higher in the dry season (by 28%) compared to the rainy season and that frequent consumption of fruits (tomato, banana) and grains (quinoa) were significantly associated with 29-75% reductions in hair mercury.
This study examines hair mercury concentration (n=231) in twelve communities where ASGM has increased 4-6 fold over the past decade in comparison to concentrations of mercury in locally caught fish tissue. It evaluates general mercury exposure risks including fish and non-fish dietary items through household surveys and reports that calculations of oral reference dose using mercury content in fish underestimated observed mercury exposure (by 26%), especially in communities upstream of ASGM (by up to 48%). The study found that 86% of individuals and 77% of children exceeded the USEPA mercury provisional level of 1.2 µg/g. Adults had higher mercury concentration than children, but mercury did not differ by sex. Communities in or downstream of ASGM had the greatest prevalence of people exceeding 2.0 µg/g mercury (80% and 62%, respectively), though the highest average hair mercury concentration occurred in the upstream community of Boca Manu (4.8 µg/g). Despite having the highest hair mercury concentrations, previous studies at Boca Manu found low sediment and fish mercury concentrations. In general, fish did not correlate to hair mercury concentration, though consumption of high trophic level fish was correlated and led to a 57-168% increase in hair mercury. Hair mercury concentrations did not vary over time, with 63% of hair segments containing mercury concentrations within 20% of the most proximal 2-cm hair segment. Though average household hair mercury was negatively correlated with individual hair mercury (likely because males over 40 years had high mercury levels), children were 2-4 times more likely to exceed 1.2 µg/g if their mother exceeded this level than children whose mothers were below this level. Additionally, for children under 5 years of age, being underweight was associated with lower hair mercury concentrations, while over 80% of women of childbearing age had hair mercury concentration above 1.2 µg/g. The study also reports a 97% probability than an individual with mercury above 1.2 µg/g also had high mercury levels 8-10 months of the previous year. It also finds that hair mercury concentrations were higher in the dry season (by 28%) compared to the rainy season and that frequent consumption of fruits (tomato, banana) and grains (quinoa) were significantly associated with 29-75% reductions in hair mercury.
Yard EE, Horton J, Schier JG, Caldwell K, Sanchez C, Lewis L, and Gatanaga C. 2012. Mercury Exposure among artisanal gold miners in Madre de Dios, Peru: A cross-sectional study. Jour. of Med. Tox. 8(4): 441-448.
This study examines mercury concentrations in urine and blood of 103 residents in the ASGM community of Huaypetue. It reports 100% of participants with detectable urine mercury levels (0.7-151 µg/g creatine), 91% with detectable blood methylmercury levels (0.6-10.0 µg/L), 10.7% with blood methylmercury levels above the USEPA reference level of 5.8 µg/L, and 13% reporting neurological disorders or kidney dysfunction. Total mercury was highest for those who burned mercury-gold amalgams, and methylmercury was highest for fish consumers. Urine total mercury concentration did not differ by age, gender, highest level of education, time living in the ASGM community, or fish consumption. Blood methylmercury concentration was positively associated with a university level education, nonpublic drinking water source, and fish consumption, and negatively associated with people who mixed mercury with gold. The frequency of symptoms reported in 2010 by the Madre de Dios sample population, stratified by participation in heating amalgams, is illustrated in the figure below.
This study examines mercury concentrations in urine and blood of 103 residents in the ASGM community of Huaypetue. It reports 100% of participants with detectable urine mercury levels (0.7-151 µg/g creatine), 91% with detectable blood methylmercury levels (0.6-10.0 µg/L), 10.7% with blood methylmercury levels above the USEPA reference level of 5.8 µg/L, and 13% reporting neurological disorders or kidney dysfunction. Total mercury was highest for those who burned mercury-gold amalgams, and methylmercury was highest for fish consumers. Urine total mercury concentration did not differ by age, gender, highest level of education, time living in the ASGM community, or fish consumption. Blood methylmercury concentration was positively associated with a university level education, nonpublic drinking water source, and fish consumption, and negatively associated with people who mixed mercury with gold. The frequency of symptoms reported in 2010 by the Madre de Dios sample population, stratified by participation in heating amalgams, is illustrated in the figure below.
ENVIRONMENTAL IMPACTS OF MERCURY FROM ASGM IN PERU
Alvarez-Berrios N, Campos-Cerqueira M, Hernandez-Serna A, Delgado CJA, Roman-Danobeytia F, and Aide TM. 2016. Impacts of small-scale gold mining on birds and anurans near the Tambopata Natural Reserve, Peru, assessed using passive acoustic monitoring. Trop. Cons. Sci. 9(2): 832-851.
This paper examines vocalizing birds and anurans (frogs/toads) in the buffer zone of Tambopata National Reserve in sites that contain forests, abandoned ASGM mines, and active ASGM mines. While bird species richness did not differ by site type, fewer species of birds sensitive to disturbance were found in the active mining sites. Conversely, anuran species richness was highest in the active mining sites, and lowest in the forested site, likely because of the creation of ponds associated with ASGM. The types of bird and anuran species found at each site type also differed, with little overlap of species. Finally, 72% of forest bird species were specialists with 1-2 habitats, whereas 61% of active mine bird species were generalists with 4-6 habitats.
Beal SA, Jackson BP, Kelly MA, Stroup JS, and Landis JD. Effects of historical and modern mining on mercury deposition in southeastern Peru. Environ. Sci. & Tech. 47(22): 12715-12720.
This study examines mercury distribution over four centuries using lake sediments collected near ASGM (90-150 km) and far from preindustrial mining (>400 km). It reports elevated mercury deposition in remote Peruvian lakes from 1600-1850 associated with pre-industrial mercury use for silver mining, though the variable distribution of the depositional pattern suggests differentiated mercury emissions across the region. It also reports that modern mercury deposition in these lakes, though higher than during preindustrial times (3.4-6.9 µg/m2a-1, compared t 0.8-2.5 µg/m2a-1), modern levels are not elevated above the global average; this suggests that ASGM mercury is either locally deposited or directly enters the global mercury pool.
Diringer SE, Feingold BJ, Ortiz EJ, Gallis JA, Araujo-Flores JM, Berky A, Pan WKY, and Hsu-Kim H. 2015. River transport of mercury from artisanal and small-scale gold mining and risks for dietary mercury exposure in Madre de Dios. Environ. Sci. Proc. & Impacts: 478-487.
This study examines river sediment, suspended solids, and fish at 62 sites over 560 km of the Madre de Dios River and its tributaries. The highest concentrations of total mercury in sediment, suspended solids, and fish were found near ASGM; the highest concentrations of methylmercury and percent of mercury as methylmercury in sediments were also found near ASGM. Further downstream of ASGM, total suspended solid concentration decreased, but total particulate mercury concentrations remained elevated. The highest mercury concentrations in suspended solids were found in the ASGM tributaries of the Inambari River and Colorado River. This study also found one third of carnivorous fish collected from the Madre de Dios study area to exceed the international health mercury standard of 0.5 mg/kg, particularly near ASGM. These high fish mercury levels in fish represent a source of exposure to people across Madre de Dios.
Gutleb AC, Schenck C, and Staib E. 1997. Giant otter (Pteronura brasiliensis) at risk? Total mercury and methylmercury levels in fish and otter scats, Peru. Ambio. 26(8): 511-514.
This study examines mercury levels in fish as a food source to otters in the Madre de Dios region. Mercury in smaller fish eaten by otters was below 0.2 µg/g, a tolerable amount for otters. Larger fish up to 50 kg had levels ranging from 0.46-1.55 µg/g but were too big to be prey for otter. The study provides information on mercury levels in fish in the early 1990s, prior to the drastic increase in ASGM in the past two decades.
Gutleb AC, Schenck C, and Staib E. 1997. Giant otter (Pteronura brasiliensis) at risk? Total mercury and methylmercury levels in fish and otter scats, Peru. Ambio. 26(8): 511-514.
This study examines mercury and methylmercury in fish muscle and giant otter scat in Manu National Park and a nearby ASGM site. It reports that 68% of fish muscles have mercury concentrations above the maximum tolerable level of 0.1mg/kg fresh weight in fish for European otter consumption, and 17.6% exceed the 0.5 mg/kg fresh weight Brazilian Amazon standard for human consumption. The highest fish mercury concentration was found near he ASGM site. These levels of fish mercury pose a risk for negative health impacts in the giant otter. Low levels of mercury in otter scat suggest that most of the consumed mercury is retained within its body.
Kumar A, Divoll TJ, Ganguli PM, Trama FA, and Lamborg CH. 2018. Presence of artisanal gold mining predicts mercury bioaccumulation in five genera of bats (Chiroptera). Environ. Poll. 236: 862-870.
This study investigates methylmercury exposure in bats in Peru over time by examining historical museum specimens and samples collected in the field from ASGM- and non-ASGM-impacted areas. Bats play a major role in the movement of methylmercury from aquatic to terrestrial ecosystems. They find that bat mercury concentrations have increased over the last 100 years. In addition, methylmercury concentrations are greatest in the highest bat trophic level (insectivores), among reproductive female bats, and near ASGM.
This paper examines vocalizing birds and anurans (frogs/toads) in the buffer zone of Tambopata National Reserve in sites that contain forests, abandoned ASGM mines, and active ASGM mines. While bird species richness did not differ by site type, fewer species of birds sensitive to disturbance were found in the active mining sites. Conversely, anuran species richness was highest in the active mining sites, and lowest in the forested site, likely because of the creation of ponds associated with ASGM. The types of bird and anuran species found at each site type also differed, with little overlap of species. Finally, 72% of forest bird species were specialists with 1-2 habitats, whereas 61% of active mine bird species were generalists with 4-6 habitats.
Beal SA, Jackson BP, Kelly MA, Stroup JS, and Landis JD. Effects of historical and modern mining on mercury deposition in southeastern Peru. Environ. Sci. & Tech. 47(22): 12715-12720.
This study examines mercury distribution over four centuries using lake sediments collected near ASGM (90-150 km) and far from preindustrial mining (>400 km). It reports elevated mercury deposition in remote Peruvian lakes from 1600-1850 associated with pre-industrial mercury use for silver mining, though the variable distribution of the depositional pattern suggests differentiated mercury emissions across the region. It also reports that modern mercury deposition in these lakes, though higher than during preindustrial times (3.4-6.9 µg/m2a-1, compared t 0.8-2.5 µg/m2a-1), modern levels are not elevated above the global average; this suggests that ASGM mercury is either locally deposited or directly enters the global mercury pool.
Diringer SE, Feingold BJ, Ortiz EJ, Gallis JA, Araujo-Flores JM, Berky A, Pan WKY, and Hsu-Kim H. 2015. River transport of mercury from artisanal and small-scale gold mining and risks for dietary mercury exposure in Madre de Dios. Environ. Sci. Proc. & Impacts: 478-487.
This study examines river sediment, suspended solids, and fish at 62 sites over 560 km of the Madre de Dios River and its tributaries. The highest concentrations of total mercury in sediment, suspended solids, and fish were found near ASGM; the highest concentrations of methylmercury and percent of mercury as methylmercury in sediments were also found near ASGM. Further downstream of ASGM, total suspended solid concentration decreased, but total particulate mercury concentrations remained elevated. The highest mercury concentrations in suspended solids were found in the ASGM tributaries of the Inambari River and Colorado River. This study also found one third of carnivorous fish collected from the Madre de Dios study area to exceed the international health mercury standard of 0.5 mg/kg, particularly near ASGM. These high fish mercury levels in fish represent a source of exposure to people across Madre de Dios.
Gutleb AC, Schenck C, and Staib E. 1997. Giant otter (Pteronura brasiliensis) at risk? Total mercury and methylmercury levels in fish and otter scats, Peru. Ambio. 26(8): 511-514.
This study examines mercury levels in fish as a food source to otters in the Madre de Dios region. Mercury in smaller fish eaten by otters was below 0.2 µg/g, a tolerable amount for otters. Larger fish up to 50 kg had levels ranging from 0.46-1.55 µg/g but were too big to be prey for otter. The study provides information on mercury levels in fish in the early 1990s, prior to the drastic increase in ASGM in the past two decades.
Gutleb AC, Schenck C, and Staib E. 1997. Giant otter (Pteronura brasiliensis) at risk? Total mercury and methylmercury levels in fish and otter scats, Peru. Ambio. 26(8): 511-514.
This study examines mercury and methylmercury in fish muscle and giant otter scat in Manu National Park and a nearby ASGM site. It reports that 68% of fish muscles have mercury concentrations above the maximum tolerable level of 0.1mg/kg fresh weight in fish for European otter consumption, and 17.6% exceed the 0.5 mg/kg fresh weight Brazilian Amazon standard for human consumption. The highest fish mercury concentration was found near he ASGM site. These levels of fish mercury pose a risk for negative health impacts in the giant otter. Low levels of mercury in otter scat suggest that most of the consumed mercury is retained within its body.
Kumar A, Divoll TJ, Ganguli PM, Trama FA, and Lamborg CH. 2018. Presence of artisanal gold mining predicts mercury bioaccumulation in five genera of bats (Chiroptera). Environ. Poll. 236: 862-870.
This study investigates methylmercury exposure in bats in Peru over time by examining historical museum specimens and samples collected in the field from ASGM- and non-ASGM-impacted areas. Bats play a major role in the movement of methylmercury from aquatic to terrestrial ecosystems. They find that bat mercury concentrations have increased over the last 100 years. In addition, methylmercury concentrations are greatest in the highest bat trophic level (insectivores), among reproductive female bats, and near ASGM.
Markham KE and Sangermano F. 2018. Evaluating wildlife vulnerability to mercury pollution from artisanal and small-scale gold mining in Madre de Dios, Peru. Trop. Cons. Sci. 11.
This study examines spatially where mercury pollution is affecting or can affect wildlife by examining gamma and beta diversity of amphibians and freshwater species in relation to location of mercury pollution from ASGM. While mining occurs on 121.65 km2 of land in the Madre de Dios region, 23,250 km2 of this land (27%) is highly vulnerable to mercury pollution, particularly alongside rivers and including national park and reserve land. For rivers, 66,263 km2 of the 70,565 km2 of freshwater in the region is highly vulnerable to mercury pollution. The study notes that three of the four highest priority watersheds for amphibian protection are located between the Amarakaeri Communal Reserve and Bahuaja Sonere National Park, on unprotected land. The highest priority watershed for freshwater species protection is located on the Madre de Dios River in an area not currently part of a national protection area. The study provides the following figure summarizing priority areas to promote beta and gamma diversity of amphibians and freshwater species, respectively.
This study examines spatially where mercury pollution is affecting or can affect wildlife by examining gamma and beta diversity of amphibians and freshwater species in relation to location of mercury pollution from ASGM. While mining occurs on 121.65 km2 of land in the Madre de Dios region, 23,250 km2 of this land (27%) is highly vulnerable to mercury pollution, particularly alongside rivers and including national park and reserve land. For rivers, 66,263 km2 of the 70,565 km2 of freshwater in the region is highly vulnerable to mercury pollution. The study notes that three of the four highest priority watersheds for amphibian protection are located between the Amarakaeri Communal Reserve and Bahuaja Sonere National Park, on unprotected land. The highest priority watershed for freshwater species protection is located on the Madre de Dios River in an area not currently part of a national protection area. The study provides the following figure summarizing priority areas to promote beta and gamma diversity of amphibians and freshwater species, respectively.
Martinez G, McCord SA, Driscoll CT, Todorova S, Wu S, Araujo JF, Vega CM, and Fernandez LE. 2018. Mercury contamination in riverine sediments and fish associated with artisanal and small-scale gold mining in Madre de Dios, Peru. Int. J. Environ. Res. Public Health. 15(8): 1-15.
This study compares total mercury concentrations in sediment and fish in an ASGM-impacted river (Malinowski River) to an unimpacted river (Tambopata and Heath Rivers) to investigate if mercury levels are elevated in areas with mining. Sediment mercury concentrations decreased with increasing distance from ASGM, suggesting that ASGM is the main source of sediment mercury loading. The Malinowski River had the highest average sediment mercury concentration (23.9 µg/kg),followed by the Tambopata River (21.1 µg/kg) and the Heath River (19.2 µg/kg). The highest sediment total mercury concentration collected occurred on the Malinowski River directly downstream of ASGM with a concentration of 367.2 µg/kg, an order of magnitude higher than any other sediment collected. Sediment mercury concentration varied by season and by percent carbon, with higher concentrations found in the wet season and with higher carbon content. For fish, total mercury concentrations ranged from 0.01-1.50 mg/kg. Fish total mercury concentration normalized by ∂15N (a measure of trophic position) was highest in the Tambopata River and lowest in the Heath River, with 27% of fish in the Tambopata River exceeding the USEPA criterion of 0.3 mg/kg, compared to 13% of fish in the Heath River, and 9% of fish in the Malinowski River. Higher trophic level fish displayed higher mercury concentrations compared to lower trophic level fish, but no relationship was found between fish mercury concentration and sediment concentration, fish length, or proximity to ASGM, indicating that food web dynamics likely plays a more important role in determining fish mercury levels.
This study compares total mercury concentrations in sediment and fish in an ASGM-impacted river (Malinowski River) to an unimpacted river (Tambopata and Heath Rivers) to investigate if mercury levels are elevated in areas with mining. Sediment mercury concentrations decreased with increasing distance from ASGM, suggesting that ASGM is the main source of sediment mercury loading. The Malinowski River had the highest average sediment mercury concentration (23.9 µg/kg),followed by the Tambopata River (21.1 µg/kg) and the Heath River (19.2 µg/kg). The highest sediment total mercury concentration collected occurred on the Malinowski River directly downstream of ASGM with a concentration of 367.2 µg/kg, an order of magnitude higher than any other sediment collected. Sediment mercury concentration varied by season and by percent carbon, with higher concentrations found in the wet season and with higher carbon content. For fish, total mercury concentrations ranged from 0.01-1.50 mg/kg. Fish total mercury concentration normalized by ∂15N (a measure of trophic position) was highest in the Tambopata River and lowest in the Heath River, with 27% of fish in the Tambopata River exceeding the USEPA criterion of 0.3 mg/kg, compared to 13% of fish in the Heath River, and 9% of fish in the Malinowski River. Higher trophic level fish displayed higher mercury concentrations compared to lower trophic level fish, but no relationship was found between fish mercury concentration and sediment concentration, fish length, or proximity to ASGM, indicating that food web dynamics likely plays a more important role in determining fish mercury levels.
Moreno-Brush M, Rydberg J, Gamboa N, Storch I, and Biester H. 2016. Is mercury from small-scale gold mining prevalent in the southeastern Peruvian Amazon? Enviro. Poll. 218: 150-159.
This study examines total mercury in riverbank sediments, suspended matter and fish along the ASGM-impacted Malinowski-Tambopata river system, as well as changes in mercury concentrations over time from a sediment core taken from an oxbow lake (Cocococha). It finds that mercury concentrations in riverbank sediments (20-53 ng/g) were lower than suspended matter (400-4,000 ng/g), which the authors attribute to particle size. Mercury concentration in suspended matter in ASGM-affected areas were up to 46 times those in unaffected areas, which the authors attribute to the increased amount of suspended matter rather than increased mercury concentrations. No pattern was evident for mercury concentrations in riverbank sediments. For fish, few fish were collected in the ASGM-impacted river likely due to high sediment loading. In the sediment core, mercury concentration was low (64-86 ng/g) with no change in concentration apparent over time; variability in mercury flux over time was attributed to variable sediment flux rather than differences in atmospheric mercury deposition, with emitted mercury either retained near to its source or transported farther downstream. Sediment flux in the oxbow lake was on average 38.0 µg/m2/yr (range: 15.2-54.4 µg/m2/yr).
Moreno-Brush M, Portillo A, Brandel SD, Storch I, Tschapka M, and Biester H. 2017. Mercury concentrations in bats (Chiroptera) from a gold mining area in the Peruvian Amazon. Ecotoxicology. 27(1): 45-54.
This study examines concentrations of mercury in 204 bats found at three different distances from ASGM. It found that though all measured mercury concentrations in bats were below the toxicity threshold (10 µg/g) and within the range found in other non-ASGM locations globally, mercury concentrations in these bats was generally related to feeding behavior; higher mercury concentrations were found in omnivorous bats (1.16 µg/g) compared to frugivorous bats (0.26 µg/g). In two of the three species found at all three distances from ASGM, bats closer to ASGM had higher concentrations of mercury compared to bats at a greater distance.
This study examines total mercury in riverbank sediments, suspended matter and fish along the ASGM-impacted Malinowski-Tambopata river system, as well as changes in mercury concentrations over time from a sediment core taken from an oxbow lake (Cocococha). It finds that mercury concentrations in riverbank sediments (20-53 ng/g) were lower than suspended matter (400-4,000 ng/g), which the authors attribute to particle size. Mercury concentration in suspended matter in ASGM-affected areas were up to 46 times those in unaffected areas, which the authors attribute to the increased amount of suspended matter rather than increased mercury concentrations. No pattern was evident for mercury concentrations in riverbank sediments. For fish, few fish were collected in the ASGM-impacted river likely due to high sediment loading. In the sediment core, mercury concentration was low (64-86 ng/g) with no change in concentration apparent over time; variability in mercury flux over time was attributed to variable sediment flux rather than differences in atmospheric mercury deposition, with emitted mercury either retained near to its source or transported farther downstream. Sediment flux in the oxbow lake was on average 38.0 µg/m2/yr (range: 15.2-54.4 µg/m2/yr).
Moreno-Brush M, Portillo A, Brandel SD, Storch I, Tschapka M, and Biester H. 2017. Mercury concentrations in bats (Chiroptera) from a gold mining area in the Peruvian Amazon. Ecotoxicology. 27(1): 45-54.
This study examines concentrations of mercury in 204 bats found at three different distances from ASGM. It found that though all measured mercury concentrations in bats were below the toxicity threshold (10 µg/g) and within the range found in other non-ASGM locations globally, mercury concentrations in these bats was generally related to feeding behavior; higher mercury concentrations were found in omnivorous bats (1.16 µg/g) compared to frugivorous bats (0.26 µg/g). In two of the three species found at all three distances from ASGM, bats closer to ASGM had higher concentrations of mercury compared to bats at a greater distance.
DEFORESTATION ASSOCIATED WITH ASGM IN PERU
Asner GP, Llactayo W, and Tupayachi R. 2013. Elevated rates of gold mining in the Amazon revealed through high-resolution monitoring. PNAS. 110(46): 18454-18459.
This study uses high-resolution satellite imagery to identify gold mining activities in Madre de Dios from 1999-2012. In these thirteen years, ASGM increased by 400% from 10,000 ha to 50,000, with an average annual increase of 14%. Mine expansion tripled as a result of the 2008 global expansion to a rate of 6,145 ha/year. This expansion was primarily attributed to ASGM activities, rather than to the three large regional mines; in 2012, ASGM accounted for 51% of all mining in Madre de Dios. The expansion of ASGM also now extends to the Andean foothills that contain headwater streams (at 600-800 m elevation). Additionally, the study finds that gold mining leads to tree mortality on the borders of the mines, is the largest source of deforestation in the region, and results in enormous sediment loading of rivers. |
Asner GP and Tupayachi R. 2017. Accelerated losses of protected forests from gold mining in the Peruvian Amazon. Environ. Res. Lett. 12(9).
This study uses high-resolution remote sensing to determine the expansion of gold mining in Madre de Dios from 1999-2016. Gold mining leads to average deforestation rates of 4437 ha/year. While governmental legislation enacted in 2012 to regulate gold mining supplies decreased the rate of ASGM expansion for a year, deforestation then increased 40% from 2012-2016. The majority of ASGM occurs within 10 km of the Madre de Dios River and its tributaries. ASGM has also begun to spread to the Tambopata National Reserve and Buffer Zone, with a 37% increase in these protected areas since 2012. In the Reserve, ASGM expansion occurred at an average rate of 51 ha/year in this four year period and accounted for 521 ha of forest loss since 2016. In the Buffer Zone, forest loss from ASGM from 2012-2016 averaged 2044 ha/year and accounted for 44% of all mining in the Madre de Dios region. This study suggests that increased regulation and law enforcement are important to decreasing ASGM activities in Madre de Dios.
This study uses high-resolution remote sensing to determine the expansion of gold mining in Madre de Dios from 1999-2016. Gold mining leads to average deforestation rates of 4437 ha/year. While governmental legislation enacted in 2012 to regulate gold mining supplies decreased the rate of ASGM expansion for a year, deforestation then increased 40% from 2012-2016. The majority of ASGM occurs within 10 km of the Madre de Dios River and its tributaries. ASGM has also begun to spread to the Tambopata National Reserve and Buffer Zone, with a 37% increase in these protected areas since 2012. In the Reserve, ASGM expansion occurred at an average rate of 51 ha/year in this four year period and accounted for 521 ha of forest loss since 2016. In the Buffer Zone, forest loss from ASGM from 2012-2016 averaged 2044 ha/year and accounted for 44% of all mining in the Madre de Dios region. This study suggests that increased regulation and law enforcement are important to decreasing ASGM activities in Madre de Dios.
Caballero EJ, Rom F, Ascorra C, Fernandez LE, and Silman M. 2018. Deforestation and forest degradation due to gold mining in the Peruvian Amazon: A 34-year perspective. Remote Sensing. 10(1903): 1-17.
This study reports that ASGM in the Peruvian Amazon was associated with approximately 100,000 ha of deforestation from 1984-2017. It also finds that over half of this deforestation has occurred since 2011, with 10% of it occurring in 2017, representing the highest rates of land conversion ever recorded. Deforestation associated with ASGM was highest during construction of the Interoceanic Highway in 2006-2012 (by increasing access to previously remote areas) and during the economic recession of 2008-2009. While initially most gold mining in the Peruvian Amazon was large-scale, ASGM activity has rapidly increased since 1998, and 65% of all new mines since 2017 are ASGM. This has resulted in more cumulative deforestation by ASGM than large-scale gold mining in Madre de Dios. Protected areas generally are effective at preventing deforestation (only 4% of ASGM occurs on protected areas), though buffer zones remain active areas of ASGM activity with one third of all mining occurring on lands with some protected status (an average of 3157 ha/yr of deforestation occurring in buffer zones since 2010). Additionally, ASGM using suction mining (using suction pumps to extract sediments from rivers) is becoming more common than excavation mining (using heavy machinery to extract soil and sediment), which results in increased soil loss to rivers and increased difficulty for reforestation.
Swenson JJ, Carter CE, Domec JC, and Delgado CI. 2011. Gold mining in the Peruvian Amazon: Global prices, deforestation, and mercury imports. PLoS ONE. 6(4).
This study uses satellite imagery to draw comparisons between deforestation associated with large-scale gold mining in Madre de Dios, the international price of gold, and Peruvian imports of mercury. It shows that between 2003 and 2009, 6600 ha of land were converted to large-scale mining uses, with mining activity increasing six-fold from 2003-2006 to 2006-2009 to reach 1915 ha/year. It also shows that deforestation associated with mining is increasing nonlinearly with gold price increases (18%/year) since 2003. Finally, the study finds that the price of gold is associated with Peruvian mercury imports and estimate that mercury imports in 2011 will double from 2009 to 500 t/year. The authors speculate that this trend will continue into the future as the gold price continues to increase and also estimates that the full extent of mining is even larger than their calculations since their scale of resolution does not take into account most ASGM activities.
This study reports that ASGM in the Peruvian Amazon was associated with approximately 100,000 ha of deforestation from 1984-2017. It also finds that over half of this deforestation has occurred since 2011, with 10% of it occurring in 2017, representing the highest rates of land conversion ever recorded. Deforestation associated with ASGM was highest during construction of the Interoceanic Highway in 2006-2012 (by increasing access to previously remote areas) and during the economic recession of 2008-2009. While initially most gold mining in the Peruvian Amazon was large-scale, ASGM activity has rapidly increased since 1998, and 65% of all new mines since 2017 are ASGM. This has resulted in more cumulative deforestation by ASGM than large-scale gold mining in Madre de Dios. Protected areas generally are effective at preventing deforestation (only 4% of ASGM occurs on protected areas), though buffer zones remain active areas of ASGM activity with one third of all mining occurring on lands with some protected status (an average of 3157 ha/yr of deforestation occurring in buffer zones since 2010). Additionally, ASGM using suction mining (using suction pumps to extract sediments from rivers) is becoming more common than excavation mining (using heavy machinery to extract soil and sediment), which results in increased soil loss to rivers and increased difficulty for reforestation.
Swenson JJ, Carter CE, Domec JC, and Delgado CI. 2011. Gold mining in the Peruvian Amazon: Global prices, deforestation, and mercury imports. PLoS ONE. 6(4).
This study uses satellite imagery to draw comparisons between deforestation associated with large-scale gold mining in Madre de Dios, the international price of gold, and Peruvian imports of mercury. It shows that between 2003 and 2009, 6600 ha of land were converted to large-scale mining uses, with mining activity increasing six-fold from 2003-2006 to 2006-2009 to reach 1915 ha/year. It also shows that deforestation associated with mining is increasing nonlinearly with gold price increases (18%/year) since 2003. Finally, the study finds that the price of gold is associated with Peruvian mercury imports and estimate that mercury imports in 2011 will double from 2009 to 500 t/year. The authors speculate that this trend will continue into the future as the gold price continues to increase and also estimates that the full extent of mining is even larger than their calculations since their scale of resolution does not take into account most ASGM activities.
SOCIOECONOMIC CONCERNS ASSOCIATED WITH ASGM IN PERU
Fisher J, Arora P, and Rhee S. 2018. Conserving tropical forests: Can sustainable livelihoods outperform artisanal or informal mining? Sustainability, 10(2586): 1-12.
This study examines the economic viability of three main sources of livelihood in the buffer zone of Tambopata National Reserve in Madre de Dios: ASGM, fish farming, and Brazil nut harvesting. While the study finds that with current practices, ASGM is the most lucrative, it finds that if value creation at product origin is increased, fish farming and Brazil nut harvesting can be more profitable than ASGM. Currently, the majority of low skilled workers and migrants are employed by ASGM. However, the estimated average income of Brazil nut harvesting is estimated to be higher than ASGM ($8209-$13,682 compared to $8400-$10800). Brazil nut harvesting and fish farming become even more lucrative when additional markets are available allowing for the products to be sold at higher prices as organically produced or and/or in markets further away from the source (eg, Cusco). This would rely upon local partnerships to allow for these changes to be financially viable when a large group of people are collectively participating in the costs associated with organic certification, additional machines for the processing of products, and transportation of the goods.
UNEP, visited on February 11th.
The UNEP website provides the basic information with regards to the National Action Plan arising from the Minamata Convention.
This study examines the economic viability of three main sources of livelihood in the buffer zone of Tambopata National Reserve in Madre de Dios: ASGM, fish farming, and Brazil nut harvesting. While the study finds that with current practices, ASGM is the most lucrative, it finds that if value creation at product origin is increased, fish farming and Brazil nut harvesting can be more profitable than ASGM. Currently, the majority of low skilled workers and migrants are employed by ASGM. However, the estimated average income of Brazil nut harvesting is estimated to be higher than ASGM ($8209-$13,682 compared to $8400-$10800). Brazil nut harvesting and fish farming become even more lucrative when additional markets are available allowing for the products to be sold at higher prices as organically produced or and/or in markets further away from the source (eg, Cusco). This would rely upon local partnerships to allow for these changes to be financially viable when a large group of people are collectively participating in the costs associated with organic certification, additional machines for the processing of products, and transportation of the goods.
UNEP, visited on February 11th.
The UNEP website provides the basic information with regards to the National Action Plan arising from the Minamata Convention.
Photograph: X-TRAVEL PERU