Morphometric parameters and total mercury in eggs of snowy egret (Egretta thula) from Cartagena Bay and Totumo Marsh, north of Colombia

Genotoxic effects in island populations of Cartagena de Indias, Colombia due to environmental exposure to mercury and cadmium

Background

Contamination of Cartagena Bay, Colombia with heavy metals such as mercury (Hg) and cadmium (Cd) presents a major environmental and public health concern, particularly for human communities residing on nearby islands and coastal areas. These populations face enhanced exposure risks owing to their traditional fishing practices and continuous interactions with polluted marine environments. This study aimed to evaluate the genotoxic effects of environmental exposure to Hg and Cd in populations from the island zone of the Cartagena district, Bolívar.

Methods

Ninety-four individuals from the four island communities (study group) and 30 individuals from the urban area of Cartagena (control group) participated in this study. The blood samples were collected to measure total mercury (T-Hg) and Cd concentrations, and a Buccal Micronucleus Cytome (BMCyt) assay was used to evaluate exposure effects.

Results

Cadmiun levels in the blood of the study group were within the normal range and comparable to those of the control group (p > 0.05). However, the study group exhibited significantly higher T-Hg levels (7.34 μg/L) compared to the control group (2.01 μg/L), surpassing the accepted limit. Moreover, the study group showed a higher incidence of DNA damage and cell death biomarkers (p < 0.05). Additionally, significant correlations were observed between total blood Hg levels and the frequencies of micronuclei, karyorrhexis, and karyolysis.

Conclusion

These results suggest that island populations of Cartagena are exposed to high levels of Hg and exhibit genotoxic damage, indicating a problem that must be addressed.

Marine Pollution and Advances in Biomonitoring in Cartagena Bay in the Colombian Caribbean

Coastal zones sustain extensive biodiversity, support key processes for ocean dynamics, and influence the balance of the global environment. They also provide resources and services to communities, determine their culture, and are the basis for their economic growth. Cartagena Bay in the Colombian Caribbean is the place of the establishment of one of the country's main cities, which has a great historical and tourist attraction, and it is also the location of the main commercial port and a great variety of industries. Historically, it has been affected by several environmental impacts and intense pollution. This situation has gained the attention of different researchers, so herein is presented a literature review with a systematic approach using RStudio's bibliometrix on the presence of pollutants and the impact on biodiversity in recent decades, providing a critical analysis of the state of Cartagena Bay and its future needs to ensure its recovery and conservation. In addition, the socioeconomic dynamics related to the environmental state of Cartagena Bay are presented from the framework drivers, pressures, status, impacts, and responses (DPSIR). The update and critical understanding of the sources, fate, and effects of pollution are important not only for the knowledge of the status of this singular ecosystem but also to encourage future research and entrench evidence to support decision makers' actions. This review highlights that several pollutants that have been detected exceeding sediment quality guidelines, like As, Cd, Hg, and PAH, are also reported to bioaccumulate and cause damage throughout the trophic levels of the coastal environment. In addition, the potential use of sentinel species and biomarkers for their monitoring is discussed. Finally, the factors that cause pollution and threaten the state of the bay continue to exert pressure and impact; thus, there is a call for the further monitoring of this ecosystem and the strengthening of policies and regulations.

Total and methylmercury concentrations in nocturnal migratory birds passing through Mount Ailao, Southwest China

Despite growing concerns over mercury (Hg) accumulation in birds in recent decades, little is known about Hg exposure in nocturnal migratory birds. Here, total mercury (THg) and methylmercury (MeHg) were detected in the feathers of nocturnal migratory birds (n = 286, belonging to 46 species) passing through Mount Ailao in Southwest China. The stable isotope ratios of carbon (δ¹³C) and nitrogen (δ¹⁵N) were also determined to clarify the effects of trophic position, foraging guild, and foraging behavior on Hg bioaccumulation. Our results show that the THg and MeHg concentrations varied by two orders of magnitude among all nocturnal migratory birds investigated, with the lowest values (THg: 0.056 mg kg^-1; MeHg: 0.038 mg kg^-1) in the Asian koel (Eudynamys scolopaceus) and the highest (THg: 12 mg kg^-1; MeHg: 7.8 mg kg^-1) in the hair-crested drongo (Dicrurus hottentottus). Waterbirds showed higher δ¹⁵N values and higher THg and MeHg concentrations than songbirds, and the Hg concentrations in piscivorous species were significantly higher than those in herbivores, omnivores, and insectivores. Significant effects of foraging guilds (Kruskal-Wallis one-way ANOVA, p < 0.001) and foraging behaviors (Kruskal-Wallis one-way ANOVA, p < 0.001) on the Hg concentrations in migratory bird feathers were detected. A risk assessment indicated that approximately 7.0% of individuals were at moderate (2.4-5.0 mg kg^-1) to high (>5.0 mg kg^-1) risk of Hg exposure, and were therefore vulnerable to adverse physiological and behavioral effects. A long-term monitoring campaign during the migratory period is highly recommended to better understand the bioaccumulation of Hg in these nocturnal migratory bird populations over time.

South American National Contributions to Knowledge of the Effects of Endocrine Disrupting Chemicals in Wild Animals: Current and Future Directions

Human pressure due to industrial and agricultural development has resulted in a biodiversity crisis. Environmental pollution is one of its drivers, including contamination of wildlife by chemicals emitted into the air, soil, and water. Chemicals released into the environment, even at low concentrations, may pose a negative effect on organisms. These chemicals might modify the synthesis, metabolism, and mode of action of hormones. This can lead to failures in reproduction, growth, and development of organisms potentially impacting their fitness. In this review, we focused on assessing the current knowledge on concentrations and possible effects of endocrine disruptor chemicals (metals, persistent organic pollutants, and others) in studies performed in South America, with findings at reproductive and thyroid levels. Our literature search revealed that most studies have focused on measuring the concentrations of compounds that act as endocrine disruptors in animals at the systemic level. However, few studies have evaluated the effects at a reproductive level, while information at thyroid disorders is scarce. Most studies have been conducted in fish by researchers from Brazil, Argentina, Chile, and Colombia. Comparison of results across studies is difficult due to the lack of standardization of units in the reported data. Future studies should prioritize research on emergent contaminants, evaluate effects on native species and the use of current available methods such as the OMICs. Additionally, there is a primary focus on organisms related to aquatic environments, and those inhabiting terrestrial environments are scarce or nonexistent. Finally, we highlight a lack of funding at a national level in the reviewed topic that may influence the observed low scientific productivity in several countries, which is often negatively associated with their percentage of protected areas.

Mercury contamination and potential health risks to Arctic seabirds and shorebirds

Since the last Arctic Monitoring and Assessment Programme (AMAP) effort to review biological effects of mercury (Hg) on Arctic biota in 2011 and 2018, there has been a considerable number of new Arctic bird studies. This review article provides contemporary Hg exposure and potential health risk for 36 Arctic seabird and shorebird species, representing a larger portion of the Arctic than during previous AMAP assessments now also including parts of the Russian Arctic. To assess risk to birds, we used Hg toxicity benchmarks established for blood and converted to egg, liver, and feather tissues. Several Arctic seabird populations showed Hg concentrations that exceeded toxicity benchmarks, with 50 % of individual birds exceeding the "no adverse health effect" level. In particular, 5 % of all studied birds were considered to be at moderate or higher risk to Hg toxicity. However, most seabirds (95 %) were generally at lower risk to Hg toxicity. The highest Hg contamination was observed in seabirds breeding in the western Atlantic and Pacific Oceans. Most Arctic shorebirds exhibited low Hg concentrations, with approximately 45 % of individuals categorized at no risk, 2.5 % at high risk category, and no individual at severe risk. Although the majority Arctic-breeding seabirds and shorebirds appeared at lower risk to Hg toxicity, recent studies have reported deleterious effects of Hg on some pituitary hormones, genotoxicity, and reproductive performance. Adult survival appeared unaffected by Hg exposure, although long-term banding studies incorporating Hg are still limited. Although Hg contamination across the Arctic is considered low for most bird species, Hg in combination with other stressors, including other contaminants, diseases, parasites, and climate change, may still cause adverse effects. Future investigations on the global impact of Hg on Arctic birds should be conducted within a multi-stressor framework. This information helps to address Article 22 (Effectiveness Evaluation) of the Minamata Convention on Mercury as a global pollutant.

Trace elements contamination assessment in marine sediments from different regions of the Caribbean Sea

Trace elements (TEs), rare earth elements (REEs), and methylmercury (MeHg) concentrations as well as mercury (Hg) and lead (Pb) isotope compositions in sediment samples collected from strategic locations along the Caribbean Sea were determined. The analyzed sediment samples were collected at different core depths from localities in Colombia, Cuba, Haiti, and the Dominican Republic. The evaluation of pollution assessment indices i.e. enrichment factors and geoaccumulation index revealed significant enrichment of several priority substances, such as Pb, Cd and Hg, in most of the sampling sites. Hg was found in extremely high concentrations (up to 22 ± 3 mg kg^-1) in bottom samples of Colombian core, which led the authors to further investigate this area with respect to the source for Hg contamination. The analysis of Hg isotope ratios in Colombian sediments and the Pb isotope ratios in all studied cores, helped in the identification of likely pollution sources and represents a critically important record of anthropogenic influence in the region. Finally, the REEs patterns determined in all samples, also provide a needed baseline for these contaminants in the Caribbean region.

Ionic Cross-Linking Fabrication of Chitosan-Based Beads Modified with FeO and TiO2 Nanoparticles: Adsorption Mechanism toward Naphthalene Removal in Seawater from Cartagena Bay Area

Polycyclic aromatic hydrocarbons (PAHs) are complex molecules produced by the thermal decomposition of organic matter in anthropogenic activities. Novel composites with enhanced physicochemical properties aim to overcome limitations such as adsorption capacity, affinity, and stability for PAHs adsorption. Composites based on chitosan are promising due to the good biocompatibility and adsorption properties. This study focuses on the facile preparation of chitosan beads modified with iron oxide (FeO) and titanium dioxide (TiO₂) nanoparticles via ionic cross-linking (Ch-FeO/TiO₂). FeO and TiO₂ were synthesized performing co-precipitation and green chemistry methods, respectively. The characterization evidenced the formation of Ch-FeO/TiO₂ with good crystallinity, excellent thermal stability, and superparamagnetic response, attributed to the presence of FeO and TiO₂ nanoparticles. High thermal stability up to 270 °C was related to the cross-linked chitosan network. The enhanced adsorption mechanism of Ch-FeO/TiO₂ was determined by removing naphthalene from water and seawater samples. The Ch-FeO/TiO₂ showed a higher adsorption capacity of 33.1 mg/g compared to 29.8 mg/g of the unmodified chitosan (un-Ch) beads. This is due to the higher functional surface area of 27.13 m²/g, compared to that of 0.708 m²/g for un-Ch. We found a rapid adsorption rate of 240 min and the maximum adsorption capacity of 149.3 mg/g for Ch-FeO/TiO₂. A large number of actives sites allows for increasing the naphthalene molecules interaction. Adsorption in seawater samples from Cartagena Bay (Colombia) exhibits an outstanding efficiency of up to 90%. These results suggest a promising, cheap, and environmentally friendly composite for remediation of water sources contaminated with complex compounds.

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.

Hydrodynamic modelling of a polluted tropical bay: Assessment of anthropogenic impacts on freshwater runoff and estuarine water renewal

A bay's capacity to buffer fluvial fluxes between the land and sea is sensitive to hydrological changes that can affect its water renewal rates. In Cartagena Bay, Colombia, pollution issues have been associated with freshwater fluxes which are projected to increase in future years. This has led to plans to reduce freshwater flows by constructing upstream hydraulic doors. Given the influence of freshwater discharge on coastal water renewal, it is important to assess how these upstream changes will affect the bay's hydrodynamic processes. This study calibrated the 3D MOHID Water model, configured with a high-resolution mixed vertical discretization to capture the bay's characteristic processes of vertical stratification and mixing. A Lagrangian transport model was used to analyze the flow of passive particle tracers and calculate water renewal time scales. Mean residence times of 3-6 days and flushing times of 10-20 days for canal water were found, while mean residence times of 23-33 days and flushing times of 70-99 days were calculated for the bay's complete water volume. An assessment of future scenarios showed that increases in freshwater runoff would result in faster water renewal in the bay, while plans to decrease freshwater discharge would result in slower water renewal in the bay. It is therefore imperative that any plans for reducing fluvial fluxes into the bay be accompanied by the control of local pollution sources, which are abundant and could worsen the bay's water quality issues should water renewal times become longer.

Mercury levels in birds and small rodents from Las Orquideas National Natural Park, Colombia

Mercury (Hg) is a heavy metal known as one of the most toxic elements on the planet. The importance of Hg on living organisms resides on its biomagnification ability. Artisanal gold extraction activities release substantial amounts of this metal, polluting the ecosystems. To assess the impact of gold mining in Las Orquideas National Natural Park (Colombia), total Hg (T-Hg) levels were evaluated from 37 bird and 8 small rodent species collected at two sites within the boundaries of the Natural Park (Abriaqui and Frontino municipalities) that have experienced some gold-extraction history. The mean concentration of T-Hg in bird feathers from both sites was 0.84 ± 0.05 μg/g fw. Differences between species were found according to diet. Total Hg levels were greater on insectivorous (1.00 ± 0.08 μg/g fw), followed by nectarivorous (0.73 ± 0.07 μg/g fw) and frugivorus (0.57 ± 0.09 μg/g fw) species. These Hg levels were greater than those found in feathers from a control sample belonging to the species Penelope perspicax (0.53 ± 0.03 μg/g fw), a frugivorous species living at the Otun Quimbaya Fauna and Flora Sanctuary, a forest without known gold mining. Mercury concentrations in the livers of small rodents were greater in specimens from Frontino (0.15 ± 0.01 μg/g fw) than those from Abriaqui (0.11 ± 0.01 μg/g fw), but levels were not different between species. These results indicate that Hg in birds depends mainly on their diet, but geographical location may affect Hg concentration in rodents. Moreover, Hg sources in natural parks of Colombia may not rely solely on gold mining, atmospheric deposition, among others factors, could be influencing its accumulation in biota.

Bioecological Aspects and Heavy Metal Contamination of the Mollusk Donax denticulatus in the Colombian Caribbean Coastline

Donax denticulatus is a key mollusk for the ecology of sandy beaches, serving as a controller of organic matter, microorganisms, and as bioindicator of heavy metals pollution. The goal of this study was to characterize some ecological aspects of D. denticulatus and its relationship with the content of heavy metals in their tissue, in three beaches of the Caribbean coast of Colombia. The results showed the study populations were different in terms of morphological characteristics and density (Berrugas-Sucre < Cartagena-Bolívar < Riohacha-Guajira), but not in sexual proportion; although density was clearly related to beach occupancy by tourists. Analysis of metals revealed tissue concentrations varied depending on the location (Greater means: Hg = 0.018 ± 0.004 in Riohacha; Pb = 0.110 ± 0.060 in Berrugas and Cd = 0.040 ± 0.010 µg/g in Cartagena). No relationships were found between morphometric variables and heavy metals content. Principal components analysis highlighted Riohacha for presenting differences respecting to Bocagrande and Berrugas in terms of physicochemical water parameters such as pH, temperature, salinity, dissolved oxygen and conductivity. Results suggest tourism rather than environmental pollution could be a sensitive factor for biota survival in Caribbean beaches.

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

Mercury (Hg) is a harmful pollutant released into the environment from gold mining activities, representing a risk to human health and the ecosystems. The aim of this study was to assess the levels of total Hg (T-Hg) in human hair, fish, sediments and air; and to determine fish consumption-based risks for T-Hg ingestion in the Choco biogeographic region, a global biodiversity hotspot located at the Colombian Pacific. Mercury concentrations in hair were measured in two locations, Quibdo, the state capital, and Paimado, a riverine community. The median T-Hg value in human hair in Quibdo was 1.26 μg/g (range: 0.02-116.40 μg/g), whereas in Paimado it was 0.67 μg/g (range: 0.07-6.47 μg/g). Mercury levels in examined locations were weakly associated with height (ρ = 0.145, P = 0.024). Air T-Hg levels in Quibdo were high inside gold shops being up to 200.9-fold greater than the background. Mercury concentrations in fish from Atrato River were above WHO limit (0.5 μg/g), with highest levels in Pseudopimelodus schultzi, Ageneiosus pardalis, Sternopygus aequilabiatus, Rhamdia quelen and Hoplias malabaricus, whereas the lowest appeared in Cyphocharax magdalenae and Hemiancistrus wilsoni. Based on fish consumption, these last two species offer low risk to human health. Sediment samples from fifty different sites of Atrato River showed low T-Hg concentrations, with little variability between stations. However, contamination factors revealed a moderate pollution in 44% of sampling sites along the river. In conclusion, Hg pollution is widespread in the Biogeographic Choco and governmental actions must be taken to protect the population and preserve its biodiversity.

Impacts of Sublethal Mercury Exposure on Birds: A Detailed Review

Mercury is a ubiquitous environmental contaminant known to accumulate in, and negatively affect, fish-eating and oceanic bird species, and recently demonstrated to impact some terrestrial songbirds to a comparable extent. It can bioaccumulate to concentrations of >1 μg/g in tissues of prey organisms such as fish and insects. At high enough concentrations, exposure to mercury is lethal to birds. However, environmental exposures are usually far below the lethal concentrations established by dosing studies.The objective of this review is to better understand the effects of sublethal exposure to mercury in birds. We restricted our survey of the literature to studies with at least some exposures >5 μg/g. The majority of sublethal effects were subtle and some studies of similar endpoints reached different conclusions. Strong support exists in the literature for the conclusion that mercury exposure reduces reproductive output, compromises immune function, and causes avoidance of high-energy behaviors. For some endpoints, notably certain measures of reproductive success, endocrine and neurological function, and body condition, there is weak or contradictory evidence of adverse effects and further study is required. There was no evidence that environmentally relevant mercury exposure affects longevity, but several of the sublethal effects identified likely do result in fitness reductions that could adversely impact populations. Overall, 72% of field studies and 91% of laboratory studies found evidence of deleterious effects of mercury on some endpoint, and thus we can conclude that mercury is harmful to birds, and the many effects on reproduction indicate that bird population declines may already be resulting from environmental mercury pollution.

Stress induced by heavy metals on breeding of magpie (Pica pica) from central Iran

The aim of this study was to address the impacts of some heavy metals (Cd, Pb, Zn, Ni and Cu) contamination on laying behavior, egg quality and breeding performance of Pica pica in north of Isfahan Province, Iran. During the breeding season of 2013, magpie's egg content and eggshell as well as nestling excrements and feathers were collected and total concentrations of heavy metals were measured by ICP-OES. Except for Zn in nestling feathers, the significantly higher concentrations of heavy metals were observed in nestling excrements than other samples. Also, comparison of heavy metals concentrations in egg content and eggshell showed that egg content had significantly higher concentrations of Zn and Pb, instead eggshell had significantly higher amount of Cu and Cd. Except for Cu, all heavy metals concentrations in eggshell had a negative relationship with morphological characters; and also concentration of Cu in egg content showed a significantly negative correlation with egg weight and volume. The most of heavy metals in nestling feathers and excrements had strongly positive correlations with each other. Also all heavy metals levels in eggshell and egg content had significantly positive correlations (except for Cu). Unhatched eggs had significantly lower weight but also greater levels of Zn, Cd, and Pb, than randomly collected eggs. No significant differences were observed for morphometric measurements of eggs between different sites, however, a decreased gradient was observed in egg volume toward the brick kiln site. Samples collected in brick kiln site accumulated higher concentrations of heavy metals than other sites. Although numbers of clutch size in brick kiln site were significantly higher than other sites, however, other breeding variable were lower than other sites. It can be suggested that ecosystem contamination may be caused to decrease the reproduction rate of Pica pica in brick kiln, probably by laying more poor quality eggs per clutch and nestling mortality.

A critical evaluation of the utility of eggshells for estimating mercury concentrations in avian eggs

Eggshells are a potential tool for nonlethally sampling contaminant concentrations in bird eggs, yet few studies have examined their utility to represent mercury exposure. We assessed mercury concentrations in eggshell components for 23 bird species and determined whether they correlated with total mercury (THg) in egg contents. We designed a multi-experiment analysis to examine how THg is partitioned into eggshell components, specifically hardened eggshells, material adhered to the eggshells, and inner eggshell membranes. The THg concentrations in eggshells were much lower than in egg contents, and almost all of the THg within the eggshell was contained within material adhered to eggshells and inner eggshell membranes, and specifically not within calcium-rich hardened eggshells. Despite very little mercury in hardened eggshells, THg concentrations in hardened eggshells had the strongest correlation with egg contents among all eggshell components. However, species with the same THg concentrations in eggshells had different THg concentrations in egg contents, indicating that there is no global predictive equation among species for the relationship between eggshell and egg content THg concentrations. Furthermore, for all species, THg concentrations in eggshells decreased with relative embryo age. Although the majority of mercury in eggshells was contained within other eggshell components and not within hardened eggshells, THg in hardened eggshells can be used to estimate THg concentrations in egg contents, if embryo age and species are addressed. Environ Toxicol Chem 2017;36:2417-2427. Published 2017 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Toxicogenomics to Evaluate Endocrine Disrupting Effects of Environmental Chemicals Using the Zebrafish Model

The extent of our knowledge on the number of chemical compounds related to anthropogenic activities that can cause damage to the environment and to organisms is increasing. Endocrine disrupting chemicals (EDCs) are one group of potentially hazardous substances that include natural and synthetic chemicals and have the ability to mimic endogenous hormones, interfering with their biosynthesis, metabolism, and normal functions. Adverse effects associated with EDC exposure have been documented in aquatic biota and there is widespread interest in the characterization and understanding of their modes of action. Fish are considered one of the primary risk organisms for EDCs. Zebrafish (Danio rerio) are increasingly used as an animal model to study the effects of endocrine disruptors, due to their advantages compared to other model organisms. One approach to assess the toxicity of a compound is to identify those patterns of gene expression found in a tissue or organ exposed to particular classes of chemicals, through new technologies in genomics (toxicogenomics), such as microarrays or whole-genome sequencing. Application of these technologies permit the quantitative analysis of thousands of gene expression changes simultaneously in a single experiment and offer the opportunity to use transcript profiling as a tool to predict toxic outcomes of exposure to particular compounds. The application of toxicogenomic tools for identification of chemicals with endocrine disrupting capacity using the zebrafish model system is reviewed.

Toxic metals and associated sporulated bacteria on Andean hummingbird feathers

Human activities in the Sabana de Bogotá, Colombia, release toxic metals such as lead (Pb) and chromium (Cr) into the environment polluting the air, water, and soil. Because birds are in contact with these pollutants and their sources, they may serve as bioindicator organisms. We evaluated the use of hummingbird feathers obtained from individuals captured in three sites of the Sabana de Bogotá as bioindicators of toxic metal pollution using spectrophotometric and spectroscopic methods based on single-feather samples. We also characterized the bacterial microbiota associated with hummingbird feathers by molecular identification using the 16S rRNA with a special focus on sporulated bacteria. Finally, we described the interactions which naturally occur among the feathers, their associated bacteria, and pollutants. We found differences in Pb and Cr concentrations between sampling sites, which ranged from 2.11 to 4.69 ppm and 0.38 to 3.00 ppm, respectively. This may reflect the impact of the activities held in those sites which release pollutants to the environment. Bacterial assemblages mainly consisted of sporulated bacilli in the Bacillaceae family (65.7 % of the identified morphotypes). We conclude that the feathers of wild tropical birds, including hummingbirds, can be used as lead and chromium bioindicators and that bacteria growing on feathers may in fact interact with these two toxic metals.

Human exposure and risk assessment associated with mercury pollution in the Caqueta River, Colombian Amazon

Mercury (Hg) is a global contaminant posing severe risks to human health worldwide. The aim of this study was to assess the levels of total Hg (T-Hg) in human hair and fish in the Caqueta River, at the Colombian Amazon, as well as to determine fish consumption-based risks for T-Hg ingestion. T-Hg levels were measured using a direct mercury analyzer. The overall mean T-Hg level in hair for humans in the Caqueta River sample (n = 200) was 17.29 ± 0.61 μg/g (1.2 to 47.0 μg/g). Ninety-four percent of the individuals had hair T-Hg concentrations greater than the WHO threshold level (5 μg/g), and 79 % displayed levels higher than 10 μg/g. Average Hg concentrations in fish varied between 0.10-0.15 μg/g and 0.10-1.60 μg/g, for noncarnivorous and carnivorous species, respectively. Based on the maximum allowable fish consumption rate for adults, most carnivorous species should be avoided in the diet, as their target hazard quotient ranged from 2.96 up to 31.05, representing a risk for Hg-related health problems. In the light of existing evidence for elevated Hg levels in the indigenous population of the Colombian Amazon, carnivorous fish should be restricted as part of the diet, and breastfeeding should be reduced to protect children health. Most importantly, gold mining activities directly on rivers demand immediate attention from the national government to avoid extensive damage on the environment and human health.

Metals and metalloid in eight fish species consumed by citizens of Bogota D.C., Colombia, and potential risk to humans

The risk imposed upon society by consumption of foods contaminated with metals and metalloids is an environmental problem attributed to the increasing number of mining extraction activities currently underway in Colombia. The aim of the current study was to determine concentrations of mercury (Hg), lead (Pb), cadmium (Cd), and a metalloid arsenic (As) found in the species of most consumed fish species by citizens of Bogota D.C. (Colombia), and the consequent potential risk to human health was also calculated. Muscle samples of 8 fish species were obtained from 203 individuals collected through 2014. The highest metal concentrations detected were as follows: Pb in Oncorhynchus sp. (0.0595 mg/kg), Cd and Hg in Pimelodus sp. (0.0072 and 0.0579 mg/kg, respectively), and As in Scomberomorus sp (0.0471 mg/kg). Further, the levels of metal accumulation from consumption of fish were calculated utilizing the metal pollution index (MPI), with elevated values noted in Pseudoplatystoma sp (0.06 mg/kg), followed by Scomberomorus sp. and Centropomus sp. (0.05 and 0.04 mg/kg, respectively). The multiple species exposure index (Em.j) denotes the level of exposure associated with consumption of various contaminated fish species, and this level occurred in decreasing order as follows: As > Pb > Cd > Hg. The multiple chemical exposure index (Ej.m), which accounts for exposure to multiple metals, identified Prochilodus sp. as the species displaying the highest level of exposure per consumption (8 × 10(-6) mg/kg-d). The target hazard quotient (THQ) for human health indicated high levels for Hg and Cd in Prochilodus sp. (0.026 and 0.005, respectively), Pb in Oncorhynchus sp (0.025), and As in Pseudoplatistoma sp. and Centropomus sp. (0.023). Data emphasize the need for adequate nationwide public policies that promote assessment of exposure levels and potential adverse health risks associated with dietary consumption of different fish species in Colombia.