Mercury pollution by gold mining in a global biodiversity hotspot, the Choco biogeographic region, Colombia

Assessment of total mercury (Hg) in soil, sediment, and tilapia fish (Oreochromis niloticus) and health risk assessment among residents of Kitwe mining area, Zambia

Mercury (Hg) is a heavy metal of global concern because of its persistence in the environment and its ability to bioaccumulate and biomagnify in ecosystems. Despite evidence of extensive environmental pollution in the Copperbelt Province, few studies have investigated Hg contamination in the Kafue River and its tributaries in Kitwe District, Zambia. Total Hg concentrations were determined in soil, sediments, and tilapia by inductively coupled plasma mass spectrometer (ICP-MS) from the mining areas and non-mining areas. There were significant differences in the population means for soil samples (Mean (mining) = 1.066, Mean (non-mining) = 0.041, p ≤ 0.05 ) and sediment samples (Mean (mining) = 1.304, Mean (non-mining) = 0.034), p ≤ 0.05 ) between mining and non-mining areas. There were also statistically significant differences in the population means for fish samples (Mean (mining) = 0.015, Mean (non-mining) = 0.007, p ≤ 0.05 ) between mining and non-mining areas. The levels of Hg in the soil and sediments from the mining area were higher than the United States Environmental Protection Agency (USEPA) reference values of 0.3 mg/kg and 0.2 mg/kg, respectively. There was a weak positive correlation between the size of the fish (length) and Hg accumulation in the Kitwe mining area (r = 0.232, P = 0.1166). The observed correlation between Hg accumulation and length of fish was not statistically significant (P > 0.05). The EDI from the consumption of fish from the mining area was below the USEPA and WHO/FAO maximum tolerable daily intake of 0.1 µg/kg/day and 0.23 µg/kg, respectively. The THQ < 1 was also reported in the current study, suggesting that the exposure level may not cause adverse health effects during a lifetime in the human population. Although the EDI and THQ < 1 in the current study were below the USEPA and WHO/FAO maximum tolerable limit, the presence of Hg in fish in this area must be monitored due to its ability to bioaccumulate in large and predatory fish. The lower EDI value reported in the current study might be attributed to the smaller size of the tilapia fish specimens, resulting in low bioaccumulation of Hg. Since the Hg levels in sediments were above the USEPA limit, we recommend further studies on the bioavailability of Hg in humans and other fish species in the region, particularly carnivorous fish, due to Hg biomagnification to offer a clearer perspective on the environmental and health impacts.

Selenium-to-mercury ratios in popularly consumed Colombian fish: A comprehensive risk-benefit assessment

To understand the benefits and risks associated with the interaction between selenium (Se) and mercury (Hg), it is crucial to gather more information on the factors influencing the variability of their molar ratio. We analyzed Se and Hg concentrations, calculated selenium-to-mercury (Se:Hg) molar ratios, and assessed the health benefit values of selenium (HBV-Se) in commercially important fish (n = 309) from various aquatic environments in northern Colombia. Median Se concentrations were significantly higher (162.4 µg kg-1, U = 355, p = 0.01) compared to Hg concentrations (89.05 µg kg-1). Molar ratios values were greater than 1 for all 28 fish species, indicating a protective effect of Se against Hg. However, considerable variation in Se:Hg values was observed between species and sampling sites. All fish had Se:Hg values greater than 1 except for Astyanax magdalenae, Eugerres plumieri, Trachelyopterus sp. and Oreochromis niloticus. The HBV-Se values were also favorable (>1) for most species. Pelagic species had the lowest Hg concentrations (81.3 µg kg-1) but the highest Se:Hg ratios (6.4), while benthopelagic (908 µg kg-1, 5.2) and demersal species (712 µg kg-1, 3.7) showed higher Hg levels with lower Se:Hg values. There was a strong correlation between Hg levels, size (r2 = 0.94, p = 0.001) and trophic level of the fish (r2 = 0.99, p = 0.001). Similarly, Se levels showed a strong association with size (r2 = 0.96, p = 0.001) and trophic level (r2 = 0.94, p = 0.001). The findings of this study indicate that although the Se:Hg ratios suggest a protective action of Se against Hg toxicity, these values were not consistent. Variations in these ratios could have implications for assessing and managing risks associated with consuming Hg-contaminated fish. Therefore, it is crucial to continue evaluating health benefits and risks, especially in different ecosystems, including tropical ones.

The role of soil organic matter quality and mineralogy controlling the highest mercury concentration of the Brazilian mangroves

The ecological role of estuarine areas on organic matter storage is well known. However, the contributions of soil organic matter (SOM) quality and mineralogy as geochemical filters remain unclear. It requires further investigations in pursuit of contaminant retention understanding, such as mercury (Hg), one of the greatest threats to mangrove areas. We evaluated the highest Hg pollution case of the Brazilian mangroves to investigate the role of SOM and minerals composition in controlling this heavy metal fate. Soils were sampled from different forests: Laguncularia racemosa, coexistence of species, and Rhizophora mangle distributed along the Botafogo estuary. Redox potential (Eh), pH, electrical conductivity (ECe), SOM content, and granulometry were performed. Total mercury (THg) and its distribution were also determined. SOM was analyzed by the evaluation of its thermal stability and molecular composition, while mineralogy was investigated due to XRD and microscopy procedures. We identified a severe contamination, in which THg concentration achieved values up to 14.3 mg kg-1, 161-fold higher than the local background. Besides the distance from the source, THg variation along the contaminated forests was controlled by the natural heterogeneity of C groups provided by different species domains. It clearly generates different scenarios for Hg retention in estuarine areas, especially where Rhizophora mangle develops, considering their characteristics to release more refractory C, such as tannin and lignin, responsible for blocking this contaminant. Simultaneously, but with a lower contribution, pyrite (Fe sulfide) acted as a retainer, also controlling Hg fate on the soil.

Hematological Parameters and Mercury Exposure in Children Living Along Gold-Mining-Impacted Rivers in the Mojana Region, Colombia

Mercury (Hg) exposure is a key determinant of human health, arising from environmental, occupational, and domestic sources, as well as the consumption of contaminated food, particularly fish. Due to their developmental stage and heightened susceptibility, children are especially vulnerable. This study evaluated Hg contamination in a high-risk pediatric population affected by local economic activities such as small-scale gold mining, agriculture, and fishing. The objective was to determine whether exposure to this toxic metal was associated with alterations in hematological biomarkers, analyzing potential correlations with total Hg (T-Hg) levels in the hair and blood of 282 children aged 6 to 12 years in the Mojana Bolivarense (Colombia). The mean T-Hg concentration in hair was 0.88 µg/g in Magangue, 1.55 µg/g in Achi, and 0.26 µg/g in Arjona. A total of 35.0% and 44.4% of the examined minors from Magangue and Achi, respectively, exceeded the international threshold for hair Hg (1 µg/g). Likewise, blood T-Hg concentrations surpassed the recommended safety level (5 μg/L) in 39.4% of children from Achi and 0.8% from Magangue, while in Arjona, all values remained below this threshold. The geometric mean (GM) values of the hair-to-blood Hg ratio varied across locations. Spearman correlations revealed a very strong positive association between blood and hair T-Hg levels in Achi (ρ = 0.801; p < 0.01), a moderate correlation in Magangue (ρ = 0.325; p < 0.01), and some significant links with hematological parameters. Multiple linear regression analysis indicated a positive association between blood T-Hg concentration and white blood cell count (β = 0.053; p = 0.021) and granulocytes (β = 0.086; p = 0.011), as well as an inverse correlation with lymphocyte percentage (β =  - 0.353; p = 0.036). These findings suggest that Hg exposure may influence inflammatory and immunosuppressive processes, posing a potential health risk to vulnerable populations, particularly young individuals.

Presence of Nematodes, Mercury Concentrations, and Liver Pathology in Carnivorous Freshwater Fish from La Mojana, Sucre, Colombia: Assessing Fish Health and Potential Human Health Risks

Fish provide high-quality protein and essential nutrients. However, environmental pollution can lead to the accumulation of toxic substances such as mercury (Hg), with known negative impacts on human consumers. The aim of this study was to assess fish health and potential human health risks by analyzing the presence of nematodes, Hg concentrations, and liver pathology in freshwater fish from La Mojana, Colombia. For this purpose, 326 specimens were collected. Parasitic infection was evaluated using parasitological indices. Total Hg (T-Hg) was quantified using a direct mercury analyzer. Liver pathology was assessed through histopathological examination. Risk-based fish consumption limits were established by calculating the hazard quotient (HQ) and safe consumption limits. The overall prevalence and abundance of nematodes (Contracaecum sp.) were 46% and 2.72 ± 0.47 parasites/fish, respectively. Sternopygus macrurus exhibited the highest prevalence (100%) and parasite abundance (13.5 parasites/fish) during the rainy season, whereas Hoplias malabaricus demonstrated the greatest prevalence (100%) and abundance (14.8 parasites/fish) in the dry season. The average T-Hg was 0.31 ± 0.01 µg/g ww. During the rainy season, S. macrurus had the highest T-Hg levels (0.46 ± 0.08 µg/g ww); in the dry season, Cynopotamus magdalenae showed the highest T-Hg concentration (0.54 ± 0.03 µg/g ww). Significant positive relationships were recorded between T-Hg and parasite abundance, while these were negative with the condition factor. All specimens exhibited hepatic alterations. The HQ and Hg values suggest potential health risks from frequent fish consumption, especially in fish-dependent communities. These findings highlight the need for precautionary measures by health and environmental authorities to safeguard human and ecosystem health.

Influence of environmental and biological factors on mercury accumulation in fish from the Atrato River Basin, Colombia

Understanding variations in total mercury (T-Hg) levels in fish is crucial for protecting aquatic biota and human health. This article evaluates the influence of environmental factors (temperature, pH) and biological variables (feeding habits, trophic level, total length, total weight), on T-Hg concentrations in fish from the Atrato River basin, Colombia. Utilizing a robust secondary data set of 842 fish samples from 16 species collected in 2019, we conducted a comprehensive analysis of these influences. We examined differences in T-Hg accumulation rates by habitat type (pelagic, benthopelagic and demersal) and probabilistically classified species based on their feeding habits and trophic levels. Our analysis identified a hierarchy of variables influencing T-Hg levels: feeding habits > total length > estimated total weight > trophic level > water temperature > pH, with temperature being the only predictor exerting a negative influence. Together, these variables accounted for over 60% of the variability in T-Hg accumulation in fish muscle tissue. Furthermore, fish in the Atrato River exhibited differential T-Hg based on habitat type, grouping into three distinct subpopulations stratified by feeding habits and trophic levels. These findings suggest that observed T-Hg accumulation patterns are driven by the functional ecology of the organisms, phenological characteristics, metabolism, contamination patterns, biogeography, land use, and the spatial and chemical configuration of the environmental matrices of the basin. Our results emphasize the importance of understand how biological and environmental factors influence T-Hg concentrations in fish, as these factors vary across aquatic systems. This knowledge is crucial for developing effective biodiversity management strategies. While we used a machine learning approach to identify key predictors of T-Hg accumulation, we also caution against potential biases in modeling T-Hg concentrations for aquatic biota management.

Analysis of Pollutant Accumulation in the Invasive Bivalve Perna viridis: Current Status in the Colombian Caribbean 2020-2023

The Colombian Caribbean faces environmental challenges due to urbanization, industrialization, and maritime activities, which introduce pollutants such as heavy metals, hydrocarbons, and microplastics into aquatic ecosystems. Perna viridis (Asian green mussel), an invasive species that has been established in Cartagena Bay since 2009, exhibits potential bioaccumulation capacity, making it a promising biomonitor. This study assessed the concentrations of mercury (Hg), cadmium (Cd), lead (Pb), and selenium (Se) in P. viridis across two key sites-a port area at the Cartagena Bay (CB) and Virgen marsh (VM) in Colombia-from 2020 to 2023. Seasonal variations driven by La Niña and El Niño phenomena significantly influenced metal concentrations, with transitional periods modulating pollutant accumulation. The levels of trace metals in soft tissue of P. viridis (dry weight) ranged from 0.0003 to 0.0039 µg/g (Cd), 0.04 to 0.21 µg/g (Hg), 0.05 to 1.18 µg/g (Pb), and 0.0029 to 0.0103 µg/g (Se). In suspended particulate matter (SPM), Cd ranged from 0.07 to 0.33 µg/g; Pb ranged from 4.94 to 25.66 µg/g; and Hg ranged from 0.18 to 1.20 µg/g. Results revealed differences in metal concentrations between sites and seasons, highlighting the role of environmental and anthropogenic factors in pollutant distribution. The findings confirm P. viridis as an effective biomonitor of complex pollution scenarios in Cartagena Bay. However, its invasive status highlights ecological risks to be addressed, such as interaction with native bivalves and benthic community structures. These results emphasize the need for ongoing monitoring efforts to mitigate pollution and preserve marine biodiversity in the Colombian Caribbean.

Mercury-Resistant Bacteria Isolated from an Estuarine Ecosystem with Detoxification Potential

Mercury pollution is a significant environmental issue, primarily resulting from industrial activities, including gold mining extraction. In this study, 333 microorganisms were tested in increasing mercury concentrations, where 158 bacteria and 14 fungi were able to grow and remain viable at concentrations over 5.0 mg/L of mercuric chloride (II). One of the bacterial strains, Stenotrophomonas sp. INV PRT0231, isolated from the mouth of the San Juan River in the Chocó region in Colombia, showed a high mercury resistance level (MIC90 of 27 ± 9 mg/L), with a removal rate of 86.9%, an absorption rate of 1.2%, and a volatilization rate of 85.7% at pH 6.0 and 30.0 °C. The FTIR analysis showed changes in the functional groups, including fatty acid chains and methyl groups, proteins, and lipopolysaccharides associated with the carboxylate group (COO-), suggesting an important role of these biomolecules and their associated functional groups as mechanisms employed by the bacterium for mercury detoxification. Our study contributes to the understanding of the mechanisms of mercury biotransformation in microbial environmental isolates to help develop bioremediation strategies to mitigate mercury pollution caused by anthropogenic activities.

Evaluating ecological risks and metal bioavailability in post-dredging sediments of a wetland affected by artisanal gold mining

The evaluation of metal contamination, ecological risk, bioavailability, and the environmental dredging depth in sediments of two Colombian riverine systems impacted by artisanal gold mining and agricultural activities, was conducted following dredging processes. Results indicated significant contamination by Cd and Pb before dredging, based on the contamination factor (CF) and the geoaccumulation index (Igeo). Additionally, Cu and Hg were found to cause adverse biological effects according to sediment quality guidelines. Post-dredging, surface sediments exhibited a moderate ecological risk index (RI, 150-300), primarily due to increased contamination by Hg, Pb, and Cd. To mitigate this ecological risk (RI < 150), the environmental dredging depth needed to exceed 20 cm for all metals. On average, the bioavailable fraction increased 2.3 times within two months after dredging. However, the low environmental risk (%F1 = 1-10) calculated using risk assessment codes (RAC) indicates a potential risk due to metals entering the water column and bioaccumulating in organisms. These findings provide insights into the dynamics of metals and the impact of dredging activities on sediments in the Colombian Caribbean coast affected by various anthropogenic activities. The research underscores the importance of integrating sustainable practices in mining and agriculture to protect the ecological integrity of these riverine systems.

Riverine connectivity modulates elemental fluxes through a 200- year period of intensive anthropic change in the Magdalena River floodplains, Colombia

Tropical floodplain lakes are increasingly impacted by human activities, yet their pathways of spatial and temporal degradation, particularly under varying hydrological connectivity regimes and climate change, remain poorly understood. This study examines surface-sediment samples and 210Pb-dated sediment cores from six floodplain lakes, representing a gradient in hydrological connectivity in the lower Magdalena River Basin, Colombia. We analysed temporal and spatial variations in several sediment biogeochemical indicators: the concentration and flux of nutrients, heavy metals, and organic matter (OM), and redox conditions, flooding and erosion. Multiple factor analysis (MFA) of surface-sediments identified redox conditions, OM, flooding, heavy metals and lake connectivity as the main contributors to spatial variability within- and between-lakes sediments, accounting for 48 % of the total variation. Additionally, no clear distinction was found between littoral and open-water sediment characteristics. Isolated lakes sediments exhibited reductive conditions rich in OM and nutrients, whereas connected lakes sediments showed greater heavy metal enrichment and higher concentrations of coarse river-fed material. Generalised additive models identified significant changes in the biogeochemical indicators since the late 1800s, that accelerated post-1980s. Shifts in OM, erosion, flooding, redox conditions, land-cover change, heavy metals and climate were identified by MFA as the main drivers of change, explaining 60 %-71 % of the variation in the connected lakes and 53 %-72 % in the isolated lakes. Post-1980s, connected lakes transitioned from conditions of higher accumulation of OM and little erosion to higher accumulation of heavy metals and river-fed material. Conversely, isolated lakes, shifted from detrital-heavy metal-rich sediments to OM-, and nutrient-rich, reductive sediments. Sedimentation rates also surged post-1980s, particularly in highly connected lakes, from 0.14 ± 0.07 g cm² yr⁻¹ to 0.5 ± 0.5 g cm² yr⁻¹, with elevated fluxes of metals, OM and nutrients. These changes in sediment biogeochemistry align with deforestation, river regulation and prolonged dry periods, highlighting the complexities behind establishing reliable reference conditions for pollution assessments in large, human-impacted tropical river systems.

Biomonitoring of Mercury and Lead Levels in the Blood of Children Living near a Tropical River Impacted by Artisanal and Small-Scale Gold Mining in Colombia

(1) Background: Mercury and lead contamination resulting from various anthropogenic activities represents a global environmental problem and a considerable risk to the health of the human population. (2) Methods: The objective of this research was to evaluate the concentrations of mercury (Hg) and Lead (Pb) in the blood of the child population in the municipalities in the Atrato River basin using a direct Hg analyzer and graphite furnace atomic absorption spectrometry. (3) Results: In total, 171 children (5-14 years of age) were taken into account, and 18.71% (32) of the children had concentrations of Hg and Pb above the permissible values established by the WHO. In the municipality of UN, 19 children had blood Hg concentrations between 5.29 and 17.71 μg/L. In CA, two children had concentrations of 5.03 and 8.43 μg/L, separately. In the case of Pb, seven children showed concentrations between 3.60 and 4.83 μg/dL in the municipality of RQ, three in UN (3.59, 3.61, and 4.60 μg/dL), and one in Carmen de Atrato (5.47 μg/dL). (4) Conclusions: The levels of Hg and Pb in the blood of children living in the riparian areas of the Atrato River basin are related to gold mining activities in the basin and the consumption of contaminated fish.

Artisanal and small-scale gold mining and biodiversity: a global literature review

Artisanal and small-scale gold mining (ASGM) is crucial to the livelihoods of close to 20 million people in over 80 countries, including 4-5 million women, mainly in rural areas with limited alternative economic prospects, particularly in developing countries. ASGM is largely informal, which can add to the challenge of addressing negative social and environmental effects including impacts on biodiversity. However, with proper guidance, ASGM can operate in a responsible manner, using cleaner production methods that minimize impacts on human health and the environment. This study presents and analyzes the interactions between ASGM and biodiversity based on new findings from 27 ASGM National Action Plans (NAPs) developed within the framework of Article 7 and Annex C of the Minamata Convention on Mercury, as well as a global literature review of more than 100 publications. In terms of key findings according to the literature reviewed, alongside other human occupation such as agriculture and industrial activities, ASGM also has an impact on the environment and biodiversity. The interrelationship between ASGM and biodiversity, including protected areas, is pervasive at every stage of ASGM operations, from extraction to mine closure, and generates significant impacts on the surrounding ecosystems. These impacts include, in descending order of most reported impacts: deforestation, soil degradation, chemical contamination of aquatic and terrestrial systems, and changes to the turbidity of watercourses. Tropical regions and key species such as amphibians and freshwater fish are among the most affected. Singly or combined, these environmental stressors lead to loss or deterioration of habitat and, by extension, indigenous biodiversity and ecosystem services. In addition, legal, institutional, and regulatory frameworks and related measures, inadequate or non-existent in some cases, may not necessarily support sustainable practices, often resulting in exploited sites abandoned without remediation, reclamation, rehabilitation, or restoration measures. To mitigate such impacts a key recommendation arising from the literature review is to strengthen the integration of the interrelationship between ASGM and biodiversity in the implementation of existing relevant national strategies, including those developed under the NAPs. The global literature review also highlights the importance of a multi-stakeholder, systemic approach combining the use of geospatial analysis, scientific and local knowledge, as well as the adaptation of the relevant frameworks, capacity building, and awareness raising. This approach can inform decision making with a view to developing sustainable initiatives that prevent and reduce the impacts of artisanal and small-scale gold mining on ecosystems, and that preserve biodiversity.

Global mercury concentrations in biota: their use as a basis for a global biomonitoring framework

An important provision of the Minamata Convention on Mercury is to monitor and evaluate the effectiveness of the adopted measures and its implementation. Here, we describe for the first time currently available biotic mercury (Hg) data on a global scale to improve the understanding of global efforts to reduce the impact of Hg pollution on people and the environment. Data from the peer-reviewed literature were compiled in the Global Biotic Mercury Synthesis (GBMS) database (>550,000 data points). These data provide a foundation for establishing a biomonitoring framework needed to track Hg concentrations in biota globally. We describe Hg exposure in the taxa identified by the Minamata Convention: fish, sea turtles, birds, and marine mammals. Based on the GBMS database, Hg concentrations are presented at relevant geographic scales for continents and oceanic basins. We identify some effective regional templates for monitoring methylmercury (MeHg) availability in the environment, but overall illustrate that there is a general lack of regional biomonitoring initiatives around the world, especially in Africa, Australia, Indo-Pacific, Middle East, and South Atlantic and Pacific Oceans. Temporal trend data for Hg in biota are generally limited. Ecologically sensitive sites (where biota have above average MeHg tissue concentrations) have been identified throughout the world. Efforts to model and quantify ecosystem sensitivity locally, regionally, and globally could help establish effective and efficient biomonitoring programs. We present a framework for a global Hg biomonitoring network that includes a three-step continental and oceanic approach to integrate existing biomonitoring efforts and prioritize filling regional data gaps linked with key Hg sources. We describe a standardized approach that builds on an evidence-based evaluation to assess the Minamata Convention's progress to reduce the impact of global Hg pollution on people and the environment.

Common carp as an ecological indicator of environmental pollution in reservoirs of southern Spain: inferring the environmental risks of anthropogenic activities

Extraction and mineral processing, as well as the waste generated by old abandoned mining sites, are the main sources of contamination of water bodies and lands by potentially toxic elements (PTEs). The common carp (Cyprinus carpio Linnaeus 1758) has been reported to be a good ecological indicator of environmental pollution in water bodies. Hence, we evaluated the concentration of eleven PTEs (As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, and Zn) in different tissues of common carp in two reservoirs of the province of Jaén, southern Spain: El Tranco de Beas (S1) and La Fernandina (S2). We also assessed the concentration of PTEs in water and sediment samples. We used inductively coupled plasma mass spectrometry for all the collected samples. We found high concentrations of As and Fe in water in the S2 reservoir, above the maximum limits allowed by the sanitary criteria in Spain; however, the analysis of sediments indicated low ecological risk in S1 and moderate ecological risk for As in S2. The concentration of PTEs in common carp was higher in the S2 reservoir, exceeding the permissible limits in the case of As, Cd, Pb, and Zn. As and Cd showed higher concentrations in the kidney; Cu, Fe, and Zn showed higher concentrations in the liver; and Pb and Mn presented higher concentrations in the gill and gill bone. There was a good correlation between the concentrations found in water/sediment samples and those in common carp, corroborating its usefulness as a good ecological indicator, allowing the detection of environmental pollution and inferring previous or current anthropogenic activities such as mining.

Poison in the nursery: Mercury contamination in the tadpole-rearing sites of an Amazonian frog

Artisanal and small-scale gold mining (ASGM) has become a major threat for Neotropical forests. This technique for obtaining gold is a substantial driver of small-scale deforestation and the largest contributor of Hg emissions to both the atmosphere and freshwater systems globally. Previous studies have demonstrated the impacts of Hg accumulation on various aquatic ecosystems and organisms. However, its consequences in other, more discrete systems such as phytotelmata (water-holding plant structures), and the organisms therein, have so far gone unnoticed. Here, we show high concentrations of Hg (mean ± SD: 1.43 ± 2.19 ppm) in phytotelmata and other small pools, the aquatic microenvironments used by the Neotropical poison frog Dendrobates tinctorius as tadpole-rearing sites. In 17 % of the cases, we detected Hg concentrations above the severe effect level (SEL = 2 ppm) for freshwater sediments. Hg concentrations varied depending on pool characteristics and tended to increase in proximity to known ASGM sites. We did not find an effect of Hg concentration on the number of D. tinctorius tadpoles in a given pool. Tadpoles were found in pools with concentrations of up to 8.68 ppm, suggesting that D. tinctorius fathers do not avoid pools with high Hg levels for tadpole deposition. While further research is needed to determine the potential effects of Hg on tadpole development, we found an intriguing tendency for tadpoles in later developmental stages to have lower body condition when occurring in pools with higher Hg concentrations. Our findings provide evidence of relevant Hg concentrations in the terrestrial water systems used by phytotelm-breeding anurans, and highlight the need of further field and experimental studies investigating the implications of Hg contamination for tadpole development and behaviour and the overall conservation of Amazonian biodiversity.

DNA hypomethylation-associated transcriptional rewiring enables resistance to heavy metal mercury (Hg) stress in rice

Mercury (Hg) is an important hazardous pollutant that can cause phytotoxicity and harm human health through the food chain. Recently, rice (Oryza sativa L.) has been confirmed as a potential Hg bioaccumulator. Although the genetic and molecular mechanisms involved in heavy metal absorption and translocation in rice have been investigated for several heavy metals, Hg is largely neglected. Here, we analyzed one Hg-resistant line in rice (RHg) derived from a DNA methyltransferase-coding gene, OsMET1-2 heterozygous mutant. Compared with its isogenic wild-type (WT), RHg exhibited a significantly higher survival rate after Hg treatment, ameliorated oxidative damage, and lower Hg uptake and translocation. RNAseq-based comparative transcriptomic analysis identified 34 potential Hg resistance-related genes involved in phytohormone signaling, abiotic stress response, and zinc (Zn) transport. Importantly, the elevated expression of Hg resistance-related genes in RHg was highly correlated with DNA hypomethylation in their putative promoter regions. An ionomic analysis unraveled a negative correlation between Zn and Hg in roots. Moreover, Hg concentration was effectively decreased by exogenous application of Zn in Hg-stressed rice plants. Our findings indicate an epigenetic basis of Hg resistance and reveal an antagonistic relationship between Hg and Zn, providing new hints towards Hg detoxification in plants. ENVIRONMENTAL IMPLICATION: Mercury (Hg) as an important hazardous pollutant adversely impacts the environment and jeopardizes human health, due to its chronicity, transferability, persistence, bioaccumulation and toxicity. In this paper, we identified 34 potential genes that may significantly contribute to Hg resistance in rice. We find the expression of Hg resistance-related genes was highly correlated with DNA hypomethylation in their putative promoter regions. Our results also revealed an antagonistic relationship between Hg and Zinc (Zn), providing new hints towards Hg detoxification in plants. Together, findings of this study extend our current understanding of Hg tolerance in rice and are informative to breed seed non-accumulating rice cultivars.

Heavy Metal Tolerance of Microorganisms Isolated from Coastal Marine Sediments and Their Lead Removal Potential

In this study, 338 microorganisms, comprising 271 bacteria and 67 fungi, were isolated from sediment samples collected from underexplored Pacific and Caribbean regions of Colombia. Screening trials were conducted on selected strains (n = 276) to assess their tolerance to cadmium (Cd2+), lead (Pb2+), and zinc (Zn2+), leading to the identification of six bacteria capable of withstanding 750 mg·L-1 of each heavy metal ion. Three promising microorganisms, identified as Enterobacter sp. INV PRT213, Pseudomonas sp. INV PRT215, and Stenotrophomonas sp. INV PRT216 were selected for lead removal experiments using LB broth medium supplemented with 400 mg·L-1 Pb2+. Among these, Pseudomonas sp. INV PRT215 exhibited significant potential, removing 49% of initial Pb2+ after 240 min of exposure (16.7 g wet biomass·L-1, pH 5, 30 °C). Infrared spectra of Pb-exposed biomass showed changes in functional groups, including carbonyl groups of amides, carboxylate, phosphate, hydroxyl, and amine groups, compared to the not-exposed control. These changes suggested interactions between the metal and functional groups in the biomass. The findings of this study highlight the potential of microorganisms derived from coastal marine environments as promising candidates for future applications in bioremediation of polluted environments contaminated with heavy metals.

Vertical distribution and trace element contamination in sediment cores affected by gold mining in Colombia

The vertical distribution, level of contamination, potential ecological risks, and historical fluxes of trace elements (Pb, As, and Hg) were evaluated from 210Pb-dated sediment cores in three different areas with gold mining impacts in northern Colombia: the Atrato River (AR), the Delicias Marsh (DM) and the Encaramada Marsh (EM). All cores spanned ∼100 years; the mass accumulation rates followed the order AR > DM > EM. The average trace elements concentrations in the sediment cores were: Pb 2.41 ± 0.72, As 0.65 ± 0.32, Hg 0.07 ± 0.02 μg g-1 in the Atrato River; Pb 23.49 ± 2.59, As 2.46 ± 0.88, Hg 0.10 ± 0.02 μg g-1 in the Delicias Marsh; and Pb 9.76 ± 4.18, As 2.44 ± 1.26, Hg 0.17 ± 0.06 μg g-1 in the Encaramada Marsh. Sediments are classified according to the contamination factor (CF) and geoaccumulation index (Igeo) as low to very highly contaminated. The Pollution load index (PLI) indicates environmental deterioration (PLI> 1), and the Sediment quality guidelines (SQGs) indicate that only Hg may produce adverse biological effects in the EM core. This study is an example of the reconstruction of temporal changes in pollution levels and impacts of potentially toxic elements caused by gold mining in remote ecosystems, which can be reproduced in other areas where environmental monitoring is scarce or non-existent.

Ecological and human health risk from exposure to contaminated sediments in a tropical river impacted by gold mining in Colombia

Despite being one of the most important tropical biomes in the world, the Atrato River basin has experienced a critical ecological deterioration due to gold mining, posing a significant threat to wildlife and human health. In this study, we measured the concentrations of mercury (Hg) and arsenic (As) in sediments at various swamps within the basin. Classical indices were employed to assess the associated ecological and human health risks linked to exposure to these elements. The concentrations of Hg and As in the sediments ranged between 0.09 and 0.23 mg/kg and 0.59-2.68 mg/kg, respectively. The highest Hg values were found at upstream stations impacted by gold mining activities. For As, the highest levels were found near river mouth (except for station B), where agricultural practices are taken place. The contamination factor (CF) indicated that most of the sediments exhibited moderate contamination levels of Hg and As, depending on the specific sampling area. Conversely, the pollution load index (PLI) suggested a contamination level ranging from basic to moderate, with the exception of station B, which showed a progressive deterioration of the site. The geoaccumulation index (Igeo) indicated that the sediments were moderately contaminated with Hg, while showing signs of increasing contamination for As. According to the criteria for limiting effect concentrations (TEC), Hg concentrations exceeded the TEC at stations B and C, indicating a potential toxic risk to aquatic biota. A moderate potential ecological risk (PERI) was detected at downstream stations (D and E), and a high risk was detected at upstream stations (A, B and C). The hazard index (HI), used for non-carcinogenic risk assessment, suggested a risk of adverse effects on the population, particularly in children, with HI values exceeding 1. However, all lifetime cancer risk (TLCR) values fell within the acceptable range (1 × 10-6 to 1 × 10-4), indicating a negligible risk. Oral ingestion and inhalation were identified as the two primary routes of concern. This study serves as a valuable reference for risk assessment regarding exposures to environmental matrices that may not pose an immediate risk to human health.

Multi-Year Monitoring of the Toxicological Risk of Heavy Metals Related to Fish Consumption by the Population of the Kendari Region (Southeast Sulawesi, Indonesia)

This study measured the concentrations of Hg, As, Ni, Cd, and Pb in six fish species commonly consumed in Kendari. Samples were bought within local markets from 2012 to 2017 at the end of the dry season. Results showed that mercury concentrations fluctuated between years and within species, except in the Caranx sexfasciatus, which showed no significant differences (Kruskall-Wallis, p-value > 0.05, df = 5) and an average concentration of 0.371 ± 0.162 µg g-1 DW. Arsenic was found in high concentrations across species and years and varied widely in C. sexfasciatus, the lowest value being 0.32 ± 0.01 µg g-1 DW in 2012 and the highest was 5.63 ± 1.89 µg g-1 DW in 2017. The highest nickel concentrations were found in 2016 across four of the six species. The fish samples displayed very low cadmium and lead concentrations throughout the study. In addition, the potential human health risk due to fish consumption was assessed. This showed that mercury is the only one of the five metals present in concentrations high enough to individually pose a potential hazard, the only metal likely to be accumulated beyond a safe concentration in Kendari. Chanos chanos never posed a toxicological risk based on the results of this research.

Toxic metal(loids) levels in the aquatic environment and nuclear alterations in fish in a tropical river impacted by gold mining

The Atrato River basin was protected by Colombian law due to anthropogenic impacts, mainly from illegal gold mining, which triggered a critical environmental health problem. In this study we quantified mercury (Hg), methylmercury (MeHg) and arsenic (As) concentrations in aquatic environmental matrices, and explored for the first-time nuclear degenerations in fish from the Atrato River. The median concentrations (μg/kg) for T-Hg, MeHg and As in fish were 195.0, 175.5, and 30.0; in sediments (μg/kg) 165.5, 13.8 and 3.1; and in water (ng/L), 154.7 for T-Hg and 2.1 for As. A 38% and 10% of the fish exceeded the WHO limit for the protection of populations at risk (200 μg Hg/kg) and for human consumption (500 μg Hg/kg); while As concentrations were below the international standard (1000 μg/kg) in all fish. The percentage of MeHg was 89.7% and the highest accumulation was observed in carnivorous fish (336.3 ± 245.6 μg/kg, p < 0.05) of high consumption, indicating risk to human health. In water, T-Hg concentrations exceeded the threshold effect value of 12 ng/L, whereas As concentrations were below the threshold of 10,000 ng/L, established by USEPA. On the contrary, 33% of the sediments exceeded the quality standard of 200 μg/kg for Hg. We found that Prochilodus magdalenae was the species with the highest susceptibility to nuclear alterations in its order, nuclear bud (CNB, 3.7 ± 5.4%), micronuclei (MN, 1.6 ± 2.5%) and binucleated cells (BC, 1.6 ± 2.3%). These results indicate that the species appears to be a good predictor of genotoxicity in the Atrato River. Fulton's condition factor (K) indicated that 31.7% of the fishes had poor growth condition, suggesting that the Atrato River basin needs to be monitored and restored in accordance with the agreements reached in the Minamata Convention on Mercury.

Determination of methylmercury and inorganic mercury in human hair samples of individuals from Colombian gold mining regions by double spiking isotope dilution and GC-ICP-MS

With the aim to distinguish between routes of exposition to mercury (Hg) in artisanal and small-scale gold mining (ASGM) communities and to distinguish between Hg contamination sources, Hg species composition should be performed in human biomarkers. In this work, Hg species-specific determination were determined in human hair samples (N = 96), mostly non-directly occupied in ASGM tasks, from the six most relevant gold mining Colombian regions. Therefore, MeHg, Hg(II) and THg concentrations were simultaneously determined by double spiking species-specific isotope dilution mass spectrometry (IDMS) and GC-ICP-MS. Only 16.67% of participants were involved at some point in AGSM works and fish consumption ranged from 3 to 7 times/week, which is between medium and high intake levels. The median concentration of THg obtained from all samples is higher than the reference dose weekly acceptable of MeHg intake established by the EPA (1 ppm), whereas a 25% were more than 4 times higher than the WHO level (2.2 μg Hg g^-1). Median THg value of individuals consuming fish 5-7 times per week was significantly higher (p < 0.05) than those of the other consuming groups (12.5 μg Hg g^-1). Most of the samples presented a % of MeHg relative to THg higher than 80%. The average % of Hg(II)/THg was 11% and only 10 individuals presented a Hg(II) content over 30%. No significant differences (p > 0.05) were found when the amount of Hg(II) was compared between people involved in AGSM task and people not involved. Interestingly, significant differences among the evaluated groups where found when the percentage of the Hg(II)/THg ratio of these groups were compared. In fact, people involved in AGSM tasks showed 1.7 times higher Hg(II)/THg vs. inhabitants uninvolved. This suggest that Hg(II) determination by IDMS-GC-ICP-MS could be a good proxy for evaluating Hg(II) adsorption by direct exposure to mercury vapors onto hair.

Genotoxicity effects in freshwater fish species associated with gold mining activities in tropical aquatic ecosystems

The main aim of this study was to investigate total mercury (THg), methylmercury (MeHg) and arsenic (As) concentrations, and their genotoxic effects on fish species in freshwater habitats impacted by gold mining activities in the Mojana and Bajo Cauca regions (Northern Colombia). A total of 255 individuals of Prochilodus magdalenae (PM) and Hoplias malabaricus (HM) were collected in different areas of northern Colombia, 205 in the exposed groups: Mojana 1 (61), Mojana 2 (81) and Bajo Cauca (63); and 50 individuals in the control group. Dorsal muscle was analysed for pollutants and blood to perform micronucleus (MN) and erythrocytic nuclear alterations (ENA) tests. The results of the MN revealed statistically significant (p < 0.05) genetic damage in both PM (Mojana 1 = 29.7 ± 14.2; Mojana 2 = 25 ± 6.25; Bajo Cauca= 26.6 ± 10.6) and in HM (Mojana 1 = 17.7 ± 7.8; Mojana 2 = 20.4 ± 6.3; Bajo Cauca= 20.8 ± 9.8) compared to the control group (PM= 10.5 ± 3.6; HM= 9.1 ± 3.9). Likewise, the frequency of ENA was statistically higher in the exposed groups compared to the control group (p < 0.05). On the other hand, the concentrations of THg, MeHg and As found in tissue samples were significantly higher (p < 0.05) compared to the control group, being the Bajo Cauca region the area of highest risk due to high concentrations of THg (651.2 ± 344.5 μg/kg for HM and 678.5 ± 983.9 μg/kg for PM) and MeHg (504.6 ± 220.9 μg/kg for HM and 606.8 ± 886.4 μg/kg for PM). Results showed that mean THg values for both species in Bajo Cauca exceeded the WHO maximum limit (set in 500 μg Hg/kg) in fish for human consumption. Results suggest that DNA damage in erythrocytes is associated with the presence of Hg, MeHg and As, coming from mining activities.

Elemental mercury accumulation in Eichhornia crassipes (Mart.) Solms-Laubach

The aquatic macrophyte Eichhornia crassipes has great potential for the control of Hg pollution in the environment. The aim of this study was to investigate the capability of E. crassipes to accumulate elemental mercury (Hg⁰). The plants were exposed for 30 days to 5, 10, 20, 40, and 80 mg of Hg⁰ in a 1-L Hoagland medium with the Hg⁰ settled at the bottom of the flask. The roots of the plants did not touch the mercury during the treatment. After exposure, the total Hg (T-Hg) concentrations in the roots, leaves, and stems were measured using a direct mercury (Hg) analyzer. The highest concentrations were found at 80 mg Hg⁰ treatment in the roots, leaves, and stems, in that order. The translocation factor indicated a poor capability of Hg to translocate from the roots to the shoots. The relative growth and the root-length inhibition measurements showed that the differences between Hg⁰ treatments were not significant. In addition, the treatments negatively affected the chlorophyll concentration. The carotenoid content was found to be significantly different at 20 and 40 mg of Hg⁰ in 1 L. Regarding the carbonyl index in root proteins, significant differences compared to control were found at the highest Hg treatment. Based on these results, it was shown that E. crassipes is able to take up elemental Hg from Hoagland medium. However, the Hg⁰ treatments did not show a strong stress-response activation mechanism in the evaluated plant tissues.

Health Risk Assessment for Human Exposure to Heavy Metals via Food Consumption in Inhabitants of Middle Basin of the Atrato River in the Colombian Pacific

The Atrato river basin is one of the world's most biodiverse areas; however, it is highly impacted by mercury gold mining, which generates air, water, and soil pollution. (1) Background: The concentrations of persistent heavy metal pollutants, mercury (Hg), lead (Pb), cadmium (Cd), and arsenic (As) in the fish, fruits, and vegetables most consumed by the riverside inhabitants of the middle basin of the Atrato river represent a danger to public health; (2) Methods: A total of 154 samples of different fruits and vegetables and 440 samples of fish were analyzed by atomic absorption spectroscopy. A sample of 446 people were surveyed to evaluate food consumption and carcinogenic and non-carcinogenic risk; (4) Conclusions: High concentrations of As, Hg, Pb, and Cd were identified in fish, fruits-tubers, and vegetables-stems commonly consumed by inhabitants of the middle basin of the Atrato River, which exceeded the Codex limits and the limits established by the WHO/FAO, especially for carnivorous fish species. A high carcinogenic and non-carcinogenic risk was evidenced amongst inhabitants of the middle basin of the Atrato River due to the consumption of fish contaminated with high concentrations of As, MeHg, and THg. The risk due to the consumption of vegetables was very low.

Health risk assessment for human exposure to mercury species and arsenic via consumption of local food in a gold mining area in Colombia

The risk to human health from exposure to certain pollutants through the consumption of fruits, tubers, and fish were evaluated in a settlement located in a Colombian area highly impacted by gold mining activities. The concentrations of mercury (Hg) and arsenic (As) in edible food tissues and methylmercury (MeHg) in fish were determined for risk assessment. A questionnaire-based dietary survey was answered by 178 residents of three population groups: children (CHD), women of childbearing age (WCBA), and the rest of the population (RP). The estimated weekly intake (EWI) of MeHg presented values of 1.9 and 2.4 times higher than the provisional tolerable weekly intake (1.6 μg/kg BW/week) recommended by the FAO/WHO for CH and WCBA, respectively. The results of the HQ values of As and Hg for different food were above the safety level (HQ < 1) for most of the groups. For Hg, the highest HQ values correspond to fish, whereas for As in most of the food, but specially in fruits. The total target hazard quotients (HI) were higher than 1, in all the groups (except for CHD that consume tubers) indicating potential non-carcinogenic health risks. The values of carcinogenic risk (CR) for As through exposure to food ranged from 1.2·10^-4 to 7.7·10^-4, well above than the safety level of US EPA risk (10^-4-10^-6), suggesting the probability of carcinogenic risk for the entire population via ingestion. Therefore, safety control mechanisms and environmental education strategies should be applied to address food intake, associated with good agricultural practices to provide solutions to protect the health of the residents in areas affected by gold mining activities.

Adverse Health Effects and Mercury Exposure in a Colombian Artisanal and Small-Scale Gold Mining Community

The aim of this study was, first of all, to associate the mercury (Hg) concentrations and respiratory functions of the gold miners in the artisanal small-scale gold mining (ASGM) environment in San Martín de Loba, Colombia. We carried out a cross-sectional study using a survey whereby we collected basic demographic information, occupational medical history, and applied two validated questionnaires (Q16 and SF36). We measured Hg levels in all volunteers using direct thermal decomposition-atomic absorption spectrometry. Univariate and bivariate statistical analyses were carried out for all variables, performing logistic regression to assess the effect of ASGM on health outcomes. Volunteers enrolled (n = 124) were between the ages of 20 and 84 years (84% miners and 79% males). No changes were found in the systolic blood pressure, diastolic blood pressure, and heart rate from the ASGM miners, in crude and adjusted statistical analyses. ASGM miners increased 8.91 (95% confidence interval, 1.55-95.70) times the risk of having these than of having neurotoxic effects. Concentrations of total whole blood mercury (T-Hg) in all participants ranged from 0.6 to 82.5 with a median of 6.0 μg/L. Miners had higher T-Hg concentrations than non-miners (p-value = 0.011). Normal and abnormal respiratory spirometry patterns showed significant differences with the physical role and physical function of quality-of-life scales (the (p-value was 0.012 and 0.004, respectively). The spirometry test was carried out in 87 male miners, with 25% of these miners reporting abnormalities. Out of these, 73% presented a restrictive spirometry pattern, and 27%, an obstructive spirometry pattern. The ASGM population had higher Hg concentrations and worse neurotoxic symptomatology than non-miners of the same community.

Biomonitoring of mercury in water, sediments, and fish (brown and rainbow trout) from remote alpine lakes located in the Himalayas, Pakistan

Mercury (Hg) contamination of aquatic ecological units and subsequent bioaccumulation are major environmental problems of international scope. Moreover, the biogeochemistry of Hg in the remote alpine lakes aquatic ecosystem in the Himalayas remains largely unexplored. The current study investigated Hg concentrations in different environmental compartments such as water, fish, and sediments in the remote alpine lakes (RALs) including Glacial-fed Lake, Ice melting-fed Lake, and Rain-fed Lake in northern areas of Pakistan. The mean concentration of Hg in Rain-fed Lake water was (1.07 µg L-1), Ice melting-fed Lake (1.16 µg L-1), and Glacial-fed Lake (1.95 µg L-1). For fish muscle tissues, mean concentration of Hg was 1.02 mg kg-1 in the Rain-fed Lake, and 1.2 mg kg-1 for the Ice melting-fed Lake, and 1.51 mg kg-1 in the Glacial-fed Lake. Meanwhile, 0.27 mg kg-1 was observed for sediments in the Rain-fed Lake, 0.33 mg kg-1 for the Ice melting-fed Lake, and 0.38 mg kg-1 for the Glacial-fed Lake, respectively. Chronic daily intake (CDI) and potential health quotient (PHQ) for water showed high health risk in Glacial-fed Lake and low in Rain-fed Lake (PHQ < 1). The target hazard quotient (THQ) values for both the Brown and Rainbow trout in all the studied lakes water were less than 1, indicating no health risk. Furthermore, the Hg level showed high level of contamination in the sediments of all the studied lakes (190 ≤ RI < 380). Overall, Glacial-fed Lake water was more polluted with Hg, as compared to Rain-fed Lake and Ice melting-fed Lake. In the light of the abovementioned results, further research work is urgently needed to shed light on the biological and geochemical monitoring of Hg in arid high-altitude ecosystems along with source identification, mercury speciation, and other potential pollutants.

A human health risk assessment of methylmercury, arsenic and metals in a tropical river basin impacted by gold mining in the Colombian Pacific region

The Atrato River basin is one of the most biodiverse areas worldwide, and paradoxically, it is one of the sites in Colombia with the highest environmental impact from gold mining. This study assessed the distribution of Hg, As, Pb, and Cd in 47 fish species (n = 1372) and the accumulative human health risk in inhabitants (n = 2325) from 13 municipalities located along the Atrato River basin. The results revealed that Hg and As in fish present a high potential human health risk based on their mean concentrations. Estimated daily intake (EDI) calculations showed that humans could present detrimental health effects, while that target hazard quotient (THQ) above 1 showed that the exposed population might experience noncarcinogenic health risks, mainly from the accumulative effects of Hg (80.4%) and As (18.2%). The species that would most affect the health of the inhabitants are carnivorous H. malabaricus, A. pardalis, P. schultzi, R. quelen, and C. kraussii, which are among the fourteen most consumed in the region. These species had values of estimated weekly intake (EWI) above the provisional tolerable weekly intake thresholds for MeHg (PTWI of 1.6 and 3.2 μg/kg bw/week for adults and children, respectively) in 7 of the 13 localities evaluated. According to the surveys, the calculated weekly allowable fish amount (MFW) showed that carnivorous fish may generate adverse effects on the consumers because the allowed MeHg is about 2 times higher than the upper reference limit. Other results indicate a significant carcinogenic health risk, mainly from As, in 8 of the 13 localities evaluated. Due to the high rates of unsatisfied basic needs and the monetary poverty in the region, the possibility that inhabitants can replace fish as the principal source of protein is low. Therefore, a food guidance is required to avoid risks, obtain nutritional benefits, and sustain fish populations.

Poison frog social behaviour under global change: potential impacts and future challenges

The current and cascading effects of global change challenges the interactions both between animal individuals (i.e. social and sexual behaviour) and the environment they inhabit. Amphibians are an ecologically diverse class with a wide range of social and sexual behaviours, making them a compelling model to understand the potential adaptations of animals faced with the effects of human-induced rapid environmental changes (HIREC). Poison frogs (Dendrobatoidea) are a particularly interesting system, as they display diverse social behaviours that are shaped by conspecific and environmental interactions, thus offering a tractable system to investigate how closely related species may respond to the impacts of HIREC. Here, we discuss the potential impacts of global change on poison frog behaviour, and the future challenges this group may face in response to such change. We pay special attention to parental care and territoriality, which are emblematic of this clade, and consider how different species may flexibly respond and adapt to increasingly frequent and diverse anthropogenic stress. More specifically, we hypothesise that some parents may increase care (i.e. clutch attendance and distance travelled for tadpole transport) in HIREC scenarios and that species with more generalist oviposition and tadpole deposition behaviours may fare more positively than their less flexible counterparts; we predict that the latter may either face increased competition for resources limited by HIREC or will be forced to adapt and expand their natural preferences. Likewise, we hypothesise that human-driven habitat alteration will disrupt the acoustic and visual communication systems due to increased noise pollution and/or changes in the surrounding light environment. We highlight the need for more empirical research combining behavioural ecology and conservation to better predict species’ vulnerability to global change and efficiently focus conservation efforts.

Assessment of dissolved mercury by diffusive gradients in thin films devices in abandoned ponds impacted by small scale gold mining

In order to fulfil the Minamata Convention on Mercury, it is necessary to monitor the Hg contamination in freshwater ecosystems nearby artisanal and small scale gold mining (ASGM) areas. Since most of these ASGM communities are located in remote areas, a convenient method for sampling, preserving and transporting samples is needed. In this study we evaluated the feasibility of the diffusive gradient in thin-films (DGT) technique to detect and quantify the labile fraction of Hg and other metals (Pb, Cu, Zn, Cd, Ni, Mn and Cr) in a hard-to-reach gold mining district in the state of Chocó, Colombia. We deployed DGT at sampling sites along the Atrato river and abandoned mining ponds (AMPs) which were deserted in different periods since 1997 to 2019 (6-15 years). In average, the labile THg concentrations in AMPs (148.9 ± 43.2 ng L^-1) were a 50% higher than in the river water (99.9 ± 37.4 ng L^-1). In the ponds, no significant differences were found in labile Hg with respect abandonment period. Labile Ni (0.9-493.1), Mn (1.33-11.48), Cu (0.030-2.233), and Zn (0.67-10.29) (in μg L^-1) were found in higher amounts than for the rest of metals. Labile concentrations of metals are related with their downstream proximity to gold mining activities, being higher in devices deployed close to ASGM sites. Moreover, this study demonstrates the feasibility of the DGT technique to sample, transport, storage, and preserve labile Hg from hard-to-reach ASGM areas.

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.

Mercury Exposure among E-Waste Recycling Workers in Colombia: Perceptions of Safety, Risk, and Access to Health Information

Exposures to the toxic element mercury (Hg) are exceptionally high among recycling workers globally. Recycling is a growing sector in Colombia, yet workers who directly handle e-waste are often unaware of the risks of exposure to mercury from post-consumer lighting products (e.g., fluorescent lamps). This qualitative study aimed to understand how recycling workers perceive their own risks from mercury exposure and how they find information about these risks, through interviews (n = 35) at the three largest formal recycling facilities in Colombia. Workers' risk perception was generally disconnected from their likely actual exposure to mercury, instead often seen juxtaposed to co-workers who worked more directly with hazardous waste. Recycling workers, who were predominantly men from lower-income socioeconomic backgrounds, had limited knowledge of health risks due to mercury exposure and were more likely to receive health-related information from informal sources. Over a third of interviewees had searched online for information about occupational health risks of mercury, but these searches were perceived as unsatisfactory due to information being difficult to find, not available in Spanish, or related to mercury exposure via seafood or mining rather than recycling. Workers expressed (over)confidence in personal protective equipment and concern about frequent employee turnover. This study points to weaknesses in environmental health literacy and public health communication around toxic exposures to mercury in the workplace. Stronger regulation and enforcement are needed to prevent toxic exposures and promote worker health equity.

Cytogenetic toxicity from pesticide and trace element mixtures in soils used for conventional and organic crops of Allium cepa L

Pesticides and trace elements occur in complex mixtures in agroecosystems, affecting soil health and food security. Hence, it is necessary to determine their toxicity in field conditions and to develop monitoring approaches to assess conventional and organic agriculture. The aim of this research was to evaluate the associations between Allium cepa L. cytogenetic biomarkers and the realistic mixture of pesticides and trace elements found in soils of conventional, conversion, and organic crops in an intensive agricultural region in Colombia. Pesticide screening was conducted using GC-MS/MS and LC-MS/MS methods. Arsenic, cadmium, lead, and zinc were analyzed by ICP-MS; chromium, copper, nickel, and selenium by ICP-OES; and mercury by a direct analyzer. The meristematic cells in roots of Allium cepa L. were analyzed through microscopic observations to quantify cytogenetic effects. In conventional crops, 26 pesticides were detected in the soil samples, and those were below the limit of quantification in organic crops. The mean levels of As, Cd, Cr, Ni, Pb, and Se were also greater in soils of conventional crops compared to the organics. In addition, the biomarkers of cytotoxicity and genotoxicity appeared augmented in conventional samples, and those were correlated with pesticide and trace element concentrations, pollution indices, and hazard quotients. Subsequently, a discriminant function based on the mitotic index, chromosomal aberrations, and nuclear abnormalities was suitable to classify the samples by crop type. These results demonstrate the sensitivity of Allium cepa L. to the toxicity of complex mixtures in field crops and its potential as an in-situ approach for soil health monitoring in organic and conventional crop systems.

Environmental and human health risks associated with exposure to hazardous elements present in urban dust from Barranquilla, Colombian Caribbean

Urban dust is a mixture of deposited particles from different sources usually linked to potentially toxic elements (PTEs). Despite the industrialization of many South American countries, little is known about the impact of particulate matter in large cities; these data are necessary to promote environmental policies aiming to protect human health. The main objective of this work was to evaluate the particle size distribution, composition, and environmental and human health risks of settled dust particles from Barranquilla, a Colombian Caribbean industrialized area. Trace elements were analyzed by inductively coupled plasma-mass spectrometry from 35 different sites, covering all city areas. Dust was mostly composed of 10-to-70-μm particles. The average concentrations of V, Cr, Mn, Co, Ni, Cu, Zn, As, Se, Mo, Ag, Cd, Sn, Sb, Pb, and Bi were above background. High spatial heterogeneity was observed for Cu, Zn, As, Se, Mo, Ag, Sn, Sb, and Bi. Concentration factors suggest that urban dusts are extremely contaminated by Zn and Cu. The ecological risk associated with specific elements decreased in the order Cd > Cu > As > Hg > Pb > Ni > Co ≈ Zn ≈ Cr, and the contamination load index showed that 91% of the samples are polluted by PTEs. Although the carcinogenic risks of Cr, Ni, As, Co, and Cd were low, chronic exposure to several PTEs may affect quality of life. Educational programs, as well as monitoring and greater control on traffic, industry, and construction activities are needed to protect environmental and human health.

Mercury distribution in different environmental matrices in aquatic systems of abandoned gold mines, Western Colombia: Focus on human health

Total mercury (THg), methylmercury (MeHg) in water, sediments, macrophytes, fish and human health risks were analyzed and assessed from abandoned gold mining ponds (AGMPs)/ mining areas in Western Colombia to know its present environmental condition. Concentrations of THg in water (avg. 13.0 ± 13.73 ng L^-1) was above the EPA threshold level (12 ng L^-1), suggesting possible chronic effects. Sediment sample revealed that the ponds are methylated (%MeHg: 3.3-11). Macrophyte Eleocharis elegans presented higher THg content in the underground biomass (0.16 ± 0.13 µg g^-1 dw) than in the aerial biomass (0.05 ± 0.04 µg g^-1 dw) indicating accumulation of THg. MeHg was the most abundant chemical species in fish (MeHg/THg: 83.2-95.0%), signifying higher bioavailability and its risk towards human health. Fish samples (15%) indicate that THg were above WHO limit (0.5 µg g), particularly in Ctenolucius beani, Hoplias malabaricus and lowest in Sternopygus aequilabiatus and Geophagus pellegrini. Bioaccumulation and biomagnification of MeHg were higher in the carnivores representing a source of exposure and potential threat to human health. Fulton's condition factor (K) for bioaccumulation indicate a decrease with increasing trophic level of fishes. Overall results suggest, mercury species found in different AGMPs compartments should be monitored in this region.

Mercury species in fish from a tropical river highly impacted by gold mining at the Colombian Pacific region

This study was carried out in the Atrato River basin, a tropical ecosystem in northwestern Colombia, highly impacted by gold mining. The aim of this study was to show how these activities have deteriorated the quality of fish species, and how their intensity has influenced the distribution of mercury (Hg) pollution in the Atrato River basin. Results showed that total mercury (THg, n = 842) ranged between 32 ± 53 μg kg^-1 (Cyphocharax magdalenae) and 678.5 ± 345 μg kg^-1 (Agneiosus pardalis); 38% of the samples exceeded the WHO limit for the protection of populations at risk, and 15% surpassed the WHO maximum limit of THg in fish for human consumption. A significant positive correlation (p < 0.001) was found between THg with total fish length and trophic level, indicating bioaccumulation and biomagnification of mercury in fish, respectively. Using the non-migratory and carnivorous fish species Hoplias malabaricus and Caquetaia kraussii, Hg contamination was found distributed from high mining activity zones (Rio Quito, Medio Atrato, and Murindó & Vigía del Fuerte - upstream zones) to low activity areas (Rio Sucio & Carmen del Darién, and Ciénaga de Ungía & Tumaradó - downstream zones). In the first-ever performed methylmercury (MeHg) measurements in 520 fish muscle samples analyzed from the Atrato River basin, a high MeHg/THg ratio (91% of the THg) in species such as A. pardalis and H. malabaricus were recorded. Results indicated that the environment and the fish species in the Atrato River basin had been greatly affected by gold mining activities practiced on the river and its tributaries. Therefore, environmental authorities must take protection measures for the inhabitants of the area as well as for the environment.

Assessment of trace element pollution and ecological risks in a river basin impacted by mining in Colombia

Trace element pollution in rivers by anthropogenic activities is an increasing problem worldwide. In this study, the contamination and ecological risk by several trace elements were evaluated along a 100-km stretch of the San Jorge River in Colombia, impacted by different mining activities. The increase of average concentration levels and range of trace elements in sediments (in μg/g) was as follows: Cu 6656 (454-69,702) > Cd 1159 (0.061-16,227) > Zn 1064 (102-13,483) > Ni 105 (31-686) > Pb 7.2 (5.1-11.7) > As 1.8 (1.0-3.2) > Hg 0.31 (0.12-1.37). Results showed that surface sediments could be classified as very high ecological risk index (RI > 600), associated with high contamination of Hg, Cd, and Cu, in stations close mining activities. Values for pollution load index indicate an environmental deterioration (PLI > 1), and sediment quality guidelines (SQGs) suggested that Cu, Ni, Zn, and Hg caused adverse biological effects. We further used pollution indices such as contamination factor (CF), enrichment factor (EF), and geoaccumulation index (Igeo) to assess the extent of contamination. According to these indices, discharges of hazardous chemicals over many years have resulted in a high degree of pollution for Cu, Pb, and Cd, with critical values in stations receiving wastes from mining activities. Multivariate statistical analysis suggested that Hg, Cd, Cu, and Zn derived from gold and coal mining, Ni and As were related from the mining of ferronickel and coal, respectively, whereas the high Pb load was attributed to diffuse source of pollution. In sum, our study provided the first detailed database on metal concentration and ecological risks to organisms in sediments of the San Jorge River Basin, and the current results also suggested future research for public health action.

Mercury Exposure and Toxicological Consequences in Fish and Fish-Eating Wildlife from Anthropogenic Activity in Latin America

Despite the risk of significant adverse toxicological effects of Hg to humans and wildlife, Hg use in anthropogenic activities, and artisanal small-scale gold mining (ASGM) in particular, is widespread throughout Latin America. However, there are few research and monitoring studies of Hg toxicity in fish and fish-eating wildlife in Latin America compared to North America. In the present paper, we reviewed the literature from published articles and reports and summarized and assessed data on Hg in fish from 10 391 individuals and 192 species sampled across Latin America. We compared fish Hg levels with toxicity reference values (TRVs) for fish and dietary TRVs for fish-eating wildlife. We determined that fish, piscivorous birds, and other wildlife are at risk of Hg toxicity. We observed a large disparity in data quantity between North and Latin America, and identified regions requiring further investigation. In particular, future biomonitoring and research should focus on exposure of wildlife to Hg in Peru, Chile, Uruguay, the eastern and northern regions of Brazil, Venezuela, Ecuador, and Colombia. We also discuss Hg risk assessment methodological issues and recommend that future evaluations of Hg risk to wildlife must collect key physiological variables, including age, body size, and ideally Hg-to-Se molar ratios. Integr Environ Assess Manag 2021;17:13-26. © 2020 Environment and Climate Change Canada. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Negative impacts of mining on Neotropical freshwater fishes

Abstract Mining activities have significantly affected the Neotropical freshwater ichthyofauna, the most diverse in the world. However, no study has systematized knowledge on the subject. In this review, we assembled information on the main impacts of mining of crude oil, gold, iron, copper, and bauxite on aquatic ecosystems, emphasizing Neotropical freshwater fishes. The information obtained shows that mining activities generate several different disturbances, mainly via input of crude oil, metals and other pollutants, erosion and siltation, deforestation, and road construction. Mining has resulted in direct and indirect losses of fish diversity in several Neotropical waterbodies. The negative impacts on the ichthyofauna may change the structure of communities, compromise entire food chains, and erode ecosystem services provided by freshwater fishes. Particularly noteworthy is that mining activities (legal and illegal) are widespread in the Neotropics, and often located within or near protected areas. Actions to prevent and mitigate impacts, such as inspection, monitoring, management, and restoration plans, have been cursory or absent. In addition, there is strong political pressure to expand mining; if – or when – this happens, it will increase the potential of the activity to further diminish the diversity of Neotropical freshwater fishes.

A review on phytoremediation of mercury contaminated soils

Mercury (Hg) and its compounds are one of the most dangerous environmental pollutants and Hg pollution exists in soils in different degrees over the world. Phytoremediation of Hg-contaminated soils has attracted increasing attention for the advantages of low investment, in-situ remediation, potential economic benefits and so on. Searching for the hyperaccumulator of Hg and its application in practice become a research hotspot. In this context, we review the current literatures that introduce various experimental plant species for accumulating Hg and aided techniques improving the phytoremediation of Hg-contaminated soils. Experimental plant species for accumulating Hg and accumulation or translocation factor of Hg are listed in detail. The translocation factor (TF) is greater than 1.0 for some plant species, however, the bioaccumulation factor (BAF) is greater than 1.0 for Axonopus compressus only. Plant species, soil properties, weather condition, and the bioavailability and heterogeneity of Hg in soils are the main factors affecting the phytoremediation of Hg-contaminated soils. Chemical accelerator kinds and promoting effect of chemical accelerators for accumulating and transferring Hg by various plant species are also discussed. Potassium iodide, compost, ammonium sulphate, ammonium thiosulfate, sodium sulfite, sodium thiosulfate, hydrochloric acid and sulfur fertilizer may be selected to promote the absorption of Hg by plants. The review introduces transgenic gene kinds and promoting effect of transgenic plants for accumulating and transferring Hg in detail. Some transgenic plants can accumulate more Hg than non-transgenic plants. The composition of rhizosphere microorganisms of remediation plants and the effect of rhizosphere microorganisms on the phytoremediation of Hg-contaminated soils are also introduced. Some rhizosphere microorganisms can increase the mobility of Hg in soils and are beneficial for the phytoremediation.

Biomonitoring of Mercury, Cadmium and Selenium in Fish and the Population of Puerto Nariño, at the Southern Corner of the Colombian Amazon

Heavy metals threaten communities near biodiversity hotspots, as their protein sources come from the environment. This study assessed Hg, Cd, and Se concentrations in fish, as well as the magnitude of exposure and hematological conditions of adult citizens from Puerto Nariño (Colombian Amazon). Among fish samples, greater Hg concentrations were found in higher trophic level species, including Rhaphiodon vulpinus (880 ± 130 ng/g) and Pseudoplatystoma tigrinum (920 ± 87 ng/g). These species presented the highest hazard quotients and lowest Se:Hg molar ratios among those studied, showing their consumption represents a health risk to consumers. Moreover, some samples of Mylossoma duriventre and Prochilodus magdalenae had Cd levels greater than the regulated limit (100 ng/g). The average total Hg (T-Hg) concentrations in human hair and blood were 5.31 µg/g and 13.7 µg/L, respectively. All hair samples exceeded the 1.0 μg/g threshold set by the USEPA, whereas 93% of the volunteers had T-Hg blood levels greater than 5 μg/L, suggesting elevated exposure. The mean Cd level was 3.1 µg/L, with 21% of samples surpassing 5 µg/L, value at which mitigating actions should be taken. Eighty-four percent of participants presented Se deficiencies (<100 μg/L). There was a significant association between fish consumption and T-Hg in hair (ρ = 0.323; p = 0.032) and blood (ρ = 0.381; p = 0.011). In this last matrix, Se correlated with Cd content, whereas lymphocytes were inversely linked to Hg concentrations. The results of this study show that there is  extensive exposure to Hg in fish, the consumption of which may promote detrimental impacts on hematology parameters within the community.

Historical reconstruction of Small-scale gold mining activities in tropical wetland sediments in Bajo Cauca-Antioquia, Colombia

Global mining activities in Latin America have increased exponentially over the last decade. The present study aims to assess the historical impact of Artisanal and Small-scale Gold Mining activities (ASGM) in the Department of Antioquia, Colombia, a region characterized by increased mining development over the past century. Historical trends of heavy metals (i.e., Ag, Cr, Cu, Hg, Ni, Pb, and Zn) were reconstructed for the past century in a tropical wetland near the mining district. Results indicate that local mining operations did not have a significant influence in the area until the mid-20th century when metal concentrations began to increase and exceeded background values. The significant increase in both sediment accumulation rates and total organic carbon (TOC) content during the 1920s reflects the deforestation of the area due to the diversification of the economy (e.g. coffee cultivation, mining or animal husbandry). Both concentrations and accumulation rates of metals increased exponentially after the 1980s as a consequence of the reactivation of alluvial gold exploitation, reaching values that exceeded up to 2-5 times the background levels. The historical metal trends in sediments from Las Palmas wetland reflected the historical socio-economic development in Antioquia and can be used as a good proxy for evaluating anthropogenic impacts in this region.

Drivers of Forest Loss in a Megadiverse Hotspot on the Pacific Coast of Colombia

Tropical forests are disappearing at unprecedented rates, but the drivers behind this transformation are not always clear. This limits the decision-making processes and the effectiveness of forest management policies. In this paper, we address the extent and drivers of deforestation of the Choco biodiversity hotspot, which has not received much scientific attention despite its high levels of plant diversity and endemism. The climate is characterized by persistent cloud cover which is a challenge for land cover mapping from optical satellite imagery. By using Google Earth Engine to select pixels with minimal cloud content and applying a random forest classifier to Landsat and Sentinel data, we produced a wall-to-wall land cover map, enabling a diagnosis of the status and drivers of forest loss in the region. Analyses of these new maps together with information from illicit crops and alluvial mining uncovered the pressure over intact forests. According to Global Forest Change (GFC) data, 2324 km2 were deforested in this area from 2001 to 2018, reaching a maximum in 2016 and 2017. We found that 68% of the area is covered by broadleaf forests (67,473 km2) and 15% by shrublands (14,483 km2), the latter with enormous potential to promote restoration projects. This paper provides a new insight into the conservation of this exceptional forest with a discussion of the drivers of forest loss, where illicit crops and alluvial mining were found to be responsible for 60% of forest loss.

Hematological parameters and hair mercury levels in adolescents from the Colombian Caribbean

Mercury (Hg) is one of the heavy metals of concern for fish-eating populations. This pollutant can be released from many sources and generates diverse toxic effects in humans. The aim of this study was to evaluate hematological parameters and their relationship with total Hg (T-Hg) levels in the hair of adolescents from Tierrabomba, an island close to an industrialized area, and also from San Onofre, a reference site. Blood and hair samples were collected from 194 individuals, aged 11-18 years old, as well as sociodemographic and dietary information. The hematological profile showed marked differences between the two sites. Mean values for almost all variables of the red blood cell line, as well as lymphocyte percentage (LYM%) and monocyte percentage (MID%), were greater in Tierrabomba. In contrast, red cell distribution width (RDW), white blood cells (WBC), granulocyte percentage (GRA%), and plateletcrit (PTC) were higher at the reference site. Total Hg mean in Tierrabomba was 1.10 ± 0.07 μg/g, while at San Onofre, it was 1.87 ± 0.11 μg/g. In both places, more than 49% of participants had Hg concentrations over the limit threshold (1 μg/g). Overall mean corpuscular hemoglobin concentration (MCHC) and T-Hg showed a negative correlation (r = - 0.162, p = 0.024). However, positive associations were observed between T-Hg and MID% for Tierrabomba (r = 0.193, p = 0.041), and between T-Hg and mixed cells (MID) for the reference site (r = 0.223, p = 0.044). A significant relationship was found for fish consumption frequency and T-Hg levels (r = 0.360, p < 0.001). These results indicate blood parameters may be affected by Hg even at low-level exposure.

Environmental risks associated with trace elements in sediments from Cartagena Bay, an industrialized site at the Caribbean

Cartagena Bay (CB) is an industrialized site in the Caribbean. The aim of this study was to evaluate contamination patterns by trace elements in sediments from CB. Sediment samples from twelve sites in CB, and three at the Grand Marsh of Santa Marta (GMSM), a reference site, were collected during dry and rainy seasons. Forty-four trace elements were evaluated employing ICP-MS, and mercury (Hg) was measured using a Hg analyzer. Most contaminated sites corresponded to stations related to repair and maintenance of ships, with high concentrations of Cr, Cu, As and Cd; as well as in areas where cargo transshipment centers and cruise ship terminals operate, which showed elevated levels of Ba. Stations receiving inputs from petrochemical and fertilizer plants displayed high content of Pb. At the station where an extinct chlor-alkali plant was located, a high total Hg level was found, highlighting its persistence. At least 70% of the samples presented Cr, Cu, and As concentrations that were ≥ Threshold Effect Level, < Probable Effect Level, ≥ Effects Range Low and < Effects Range Medium, suggesting adverse biological effects could occur occasionally. Potential Ecological risk values revealed that only Hg and Cd may generate deleterious effects to the aquatic life. However, with few exceptions, sediment samples from CB can be considered as moderately to heavily contaminated, as shown by the I_geo. In short, the principles of ecosystem-based management should be implemented along Cartagena Bay to guarantee safe levels of trace elements in sediments and a better quality of this estuary.

Development of a Low-Cost UV-Vis Spectrophotometer and Its Application for the Detection of Mercuric Ions Assisted by Chemosensors

Detection of an environmental contaminant requires the use of expensive measurement equipment, which limits the realization of in situ tests because of their high cost, their limited portability, or the extended time duration of the tests. This paper presents in detail the development of a portable low-cost spectrophotometer which, by using a specialized chemosensor, allows detection of mercuric ions (Hg²⁺), providing effective and accurate results. Design specifications for all the stages assembling the spectrophotometer and the elements selected to build them are presented along with the process to synthesize the chemosensor and the tests developed to validate its performance in comparison with a high-precision commercial laboratory spectrophotometer.

Trace elements in sediments and fish from Atrato River: an ecosystem with legal rights impacted by gold mining at the Colombian Pacific

The Atrato watershed is a rainforest that supports exceptional wildlife species and is considered one of the most biodiversity-rich areas on the planet, currently threatened by massive gold mining. Aimed to protect this natural resource, the Constitutional Court of Colombia declared the river subject to rights. The objective of this study was to quantify trace elements in sediments and fish from Atrato watershed, assessing their environmental and human health risk. Forty-two trace elements were quantified using ICP-MS. Thirty-one elements increased their concentration downstream the river. Concentration Factors (CF) suggest sediments were moderately polluted by Cr, Cu, Cd, and strongly polluted by As. Most stations had Cr (98%) and Ni (78%) concentrations greater than the Probable Effect Concentration (PEC) criteria. Together, toxic elements generate a Pollution Load Index (PLI) and a Potential Ecological Risk Index (RI) that categorized 54% of the sediments as polluted, and 90% as moderate polluted, respectively. Hemiancistrus wilsoni, a low trophic guild fish species, had the greater average levels for Ni, Cu, As and Cd, among other elements. Rubidium and Cs showed a positive correlation with fish trophic level, suggesting these two metals biomagnify in the food chain. The Hazard Quotient (HQ) for As was greater than 1 for several species, indicating a potential risk to human health. Collectively, data suggest gold mining carried out in this biodiversity hotspot releases toxic elements that have abrogated sediment quality in Atrato River, and their incorporation in the trophic chain constitutes a large threat on environmental and human health due to fish consumption. Urgent legal and civil actions should be implemented to halt massive mining-driven deforestation to enforce Atrato River rights.