Health and ecological risk of heavy metals in agricultural soils related to Tungsten mining in Southern Jiangxi Province, China.

Background: Dayu County, a major tungsten producer in China, experiences severe heavy metal pollution. This study evaluated the pollution status, the accumulation characteristics in paddy rice, and the potential ecological risks of heavy metals in agricutural soils near tungsten mining areas of Dayu County. Furthermore, the impacts of soil properties on the accumulation of heavy metals in soil were explored. Methods: The geo-accumulation index (Igeo), the contamination factor (CF), and the pollution load index (PLI) were used to evaluate the pollution status of metals (As, Cd, Cu, Cr, Pb, Mo, W, and Zn) in soils. The ecological risk factor (RI) was used to assess the potential ecological risks of heavy metals in soil. The health risks and accumulation of heavy metals in paddy rice were evaluated using the health risk index and the translocation factor (TF), respectively. Pearson's correlation coefficient was used to discuss the influence of soil factors on heavy metal contents in soil. Results: The concentrations of metals exceeded the respective average background values for soils (As: 10.4, Cd: 0.10, Cu: 20.8, Cr: 48.0, Pb: 32.1, Mo: 0.30, W: 4.93, Zn: 69.0, mg/kg). The levels of As, Cd, Mo, and tungsten(W) exceeded the risk screening values for Chinese agricultural soil contamination and the Dutch standard. The mean concentrations of the eight tested heavy metals followed the order FJ-S > QL > FJ-N > HL > CJ-E > CJ-W, with a significant distribution throughout the Zhangjiang River basin. Heavy metals, especially Cd, were enriched in paddy rice. The Igeo and CF assessment indicated that the soil was moderately to heavily polluted by Mo, W and Cd, and the PLI assessment indicated the the sites of FJ-S and QL were extremely severely polluted due to the contribution of Cd, Mo and W. The RI results indicated that Cd posed the highest risk near tungsten mining areas. The non-carcinogenic and total carcinogenic risks were above the threshold values (non-carcinogenic risk by HQ > 1, carcinogenic risks by CR > 1 × 10-4 a-1) for As and Cd. Correlation analysis indicated that K2O, Na2O, and CaO are main factors affecting the accumulation and migration of heavy metals in soils and plants. Our findings reveal significant contamination of soils and crops with heavy metals, especially Cd, Mo, and W, near mining areas, highlighting serious health risks. This emphasizes the need for immediate remedial actions and the implementation of stringent environmental policies to safeguard health and the environment.

[Determination of cobalt and tungsten in human urine by inductively coupled plasma mass spectrometry].

Objective: To establish a inductively coupled plasma mass spectrometry method for the determination of trace cobalt and tungsten in human urine. Methods: The authors used 1% nitric acid solution as diluent in October-December 2021, the sample dilution factor and internal standard element were optimized by single factor rotation experiment, and the difference between the working curve and the standard curve was compared. Results: The method uses working curve to determine cobalt and tungsten in urine, the linear range of this method was 0.0~10.0 µg/L, the correlation coefficient was 0.999 9, the detection limits respectively were 0.005 µg/L (cobalt) and 0.09 µg/L (tungsten), the recoveries of samples respectively were 87.0%~100.2% (cobalt) and 89.4%~104.8% (tungsten), the relative standard deviations respectively were 0.4%~4.4% (cobalt) and 0.6%~3.8% (tungsten) . Conclusion: A simple and rapid method for determination of cobalt and tungsten in urine has been established. This method has the advantages of simple operation, high sensitivity, low detection limit and good stability. It is suitable for determination of cobalt and tungsten in urine of all kinds of people.

Determination of cobalt and tungsten in human urine by inductively coupled plasma mass spectrometry / 中华劳动卫生职业病杂志

Objective: To establish a inductively coupled plasma mass spectrometry method for the determination of trace cobalt and tungsten in human urine. Methods: The authors used 1% nitric acid solution as diluent in October-December 2021, the sample dilution factor and internal standard element were optimized by single factor rotation experiment, and the difference between the working curve and the standard curve was compared. Results: The method uses working curve to determine cobalt and tungsten in urine, the linear range of this method was 0.0~10.0 μg/L, the correlation coefficient was 0.999 9, the detection limits respectively were 0.005 μg/L (cobalt) and 0.09 μg/L (tungsten), the recoveries of samples respectively were 87.0%~100.2% (cobalt) and 89.4%~104.8% (tungsten), the relative standard deviations respectively were 0.4%~4.4% (cobalt) and 0.6%~3.8% (tungsten) . Conclusion: A simple and rapid method for determination of cobalt and tungsten in urine has been established. This method has the advantages of simple operation, high sensitivity, low detection limit and good stability. It is suitable for determination of cobalt and tungsten in urine of all kinds of people.

Speciation, leachability and bioaccessibility of tungsten in tungsten ore processing residue.

Tungsten ore processing residue (TOPR) poses a potential risk due to tungsten (W) leaching. However, the leachability of W in TOPR is not well understood. Herein, the mechanism of W leachability from TOPR was investigated using complementary characterization techniques and leaching experiments. Our X-ray absorption near edge structure (XANES) analysis resolved wolframite in TOPR with a distorted octahedral coordination. The sequential extraction procedure showed that 78% of mobile fraction W in TOPR were bound to Fe oxides, and consequently W leachability was positively correlated with dissolved Fe concentration as evidenced by the general acid neutralizing capacity (GANC) test. The GANC results showed that the W release was negatively correlated with Ca concentration due to CaWO4 precipitation. The in vitro gastrointestinal procedure (IVG) results indicated that organic acids, abundant in fruits and vegetables, significantly improved the bioaccessibility of W from 10% to 20% of total W in TOPR. As a consequence, accidental ingestion of TOPR with a chemical daily intake at 0.8 mg kg-1 day-1 evidenced its emerging concern in the environment and human health.

Deep-mantle krypton reveals Earth's early accretion of carbonaceous matter.

Establishing when, and from where, carbon, nitrogen and water were delivered to Earth is a fundamental objective in understanding the origin of habitable planets such as Earth. Yet, volatile delivery to Earth remains controversial1-5. Krypton isotopes provide insights on volatile delivery owing to their substantial isotopic variations among sources6-10, although pervasive atmospheric contamination has hampered analytical efforts. Here we present the full suite of krypton isotopes from the deep mantle of the Galápagos and Iceland plumes, which have the most primitive helium, neon and tungsten isotopic compositions11-16. Except for 86Kr, the krypton isotopic compositions are similar to a mixture of chondritic and atmospheric krypton. These results suggest early accretion of carbonaceous material by proto-Earth and rule out any combination of hydrodynamic loss with outgassing of the deep or shallow mantle to explain atmospheric noble gases. Unexpectedly, the deep-mantle sources have a deficit in the neutron-rich 86Kr relative to the average composition of carbonaceous meteorites, which suggests a nucleosynthetic anomaly. Although the relative depletion of neutron-rich isotopes on Earth compared with carbonaceous meteorites has been documented for a range of refractory elements1,17,18, our observations suggest such a depletion for a volatile element. This finding indicates that accretion of volatile and refractory elements occurred simultaneously, with krypton recording concomitant accretion of non-solar volatiles from more than one type of material, possibly including outer Solar System planetesimals.

Inflammatory and coagulatory markers and exposure to different size fractions of particle mass, number and surface area air concentrations in the Swedish hard metal industry, in particular to cobalt.

PURPOSE: To study the relationship between inhalation of airborne particles and cobalt in the Swedish hard metal industry and markers of inflammation and coagulation in blood. METHODS: Personal sampling of inhalable cobalt and dust were performed for subjects in two Swedish hard metal plants. Stationary measurements were used to study concentrations of inhalable, respirable, and total dust and cobalt, PM10 and PM2.5, the particle surface area and the particle number concentrations. The inflammatory markers CC16, TNF, IL-6, IL-8, IL-10, SAA and CRP, and the coagulatory markers FVIII, vWF, fibrinogen, PAI-1 and D-dimer were measured. A complete sampling was performed on the second or third day of a working week following a work-free weekend, and additional sampling was taken on the fourth or fifth day. The mixed model analysis was used, including covariates. RESULTS: The average air concentrations of inhalable dust and cobalt were 0.11 mg/m3 and 0.003 mg/m3, respectively. For some mass-based exposure measures of cobalt and total dust, statistically significant increased levels of FVIII, vWF and CC16 were found. CONCLUSIONS: The observed relationships between particle exposure and coagulatory biomarkers may indicate an increased risk of cardiovascular disease.

Raman Spectroscopy as Molybdenum and Tungsten Content Analysis Tool for Mesoporous Silica and Beta Zeolite Catalysts.

Raman spectroscopy was used for the quantitative determination of Mo and W in Mo- and W-supported mesoporous silica (Mo/SBA-15 and W/SBA-15, respectively) and Mo-supported beta zeolite (Mo-BEA). Three Raman quantitative models were developed and optimized for the metal contents of Mo/SBA-15, W/SBA-15, and Mo/BEA. Subsequently, the models were characterized using the root mean square error of calibration (RMSEC), root mean square error of cross-validation (RMSECV), root mean square error of prediction (RMSEP), correlation coefficient, and predicted residual error sum of squares (PRESS) diagnostic function. The calibration range of the models were in the range of approximately 2-40 wt% for the SBA-15 support and 1-21 wt% for the BEA support because the BEA support presented lower Mo absorption than the SBA-15 support. The RMSEC, RMSECV, and RMSEP values were below 1.80% for all developed models. The highest and lowest correlation coefficients corresponded to the W/SBA-15 (0.9984) and Mo/BEA (0.9777) models, respectively. The change in catalyst support affected the mentioned chemometric parameters (Mo/SBA-15 vs. Mo/BEA). Subsequently, Raman spectroscopy combined with the temperature control stage was used to study the calcination of Mo/BEA, Mo/SBA-15, and W/SBA-15 using three-dimensional diagrams, in which the changes in catalyst structure were analyzed as functions of the temperature and time. Raman spectroscopy was determined to be a suitable analytical tool for the quantitative analysis of the metal contents of the catalyst and optimization of the calcination process. Therefore, Raman spectroscopy can be used during catalyst manufacturing.

A novel photocatalytic reactor for the extended reuse of W-TiO2 in the degradation of sulfamethazine.

In this study, a photocatalytic reactor with a novel engineering design has been used for the extended degradation of sulfamethazine (SMZ). The reactor employed four consecutive stainless-steel plates immobilized by tungsten-dope TiO2 (W-TiO2) using polysiloxane. The characterization of W-TiO2 by X-ray diffraction (XRD), Raman spectroscopy, and energy-dispersive X-ray (EDX) denoted successful doping of tungsten in the lattice of anatase crystals of TiO2 suggesting a high photocatalytic activity under UV and visible light. A Box-Behnken experimental design was employed for the optimization of the operating parameters such as solution pH, flow rate, and the initial SMZ concentration. The residual SMZ concentration was below the detection limit after 30 min of the photocatalytic reaction under the optimum operating conditions. A highly remarkable degradation of SMZ was observed in five consecutive cycles, which reveals an extended stable photocatalytic activity offered by the reactor design. The transformation products were identified by tandem mass spectrometry, and they were employed to propose the degradation pathway. These results highlight the importance of using the photocatalysts in retained forms and open additional avenues for the practical application of photocatalysis in wastewater treatment.

Addressing K/L-edge overlap in elemental analysis from micro-X-ray fluorescence: bioimaging of tungsten and zinc in bone tissue using synchrotron radiation and laser ablation inductively coupled plasma mass spectrometry.

Synchrotron radiation micro-X-ray fluorescence (SR-µXRF) is a powerful elemental mapping technique that has been used to map tungsten and zinc distribution in bone tissue. However, the heterogeneity of the bone samples along with overlap of the tungsten L-edge with the zinc K-edge signals complicates SR-µXRF data analysis, introduces minor artefacts into the resulting element maps, and decreases image sensitivity and resolution. To confirm and more carefully delineate these SR-µXRF results, we have employed laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to untangle the problem created by the K/L-edge overlap of the tungsten/zinc pair. While the overall elemental distribution results are consistent between the two techniques, LA-ICP-MS provides significantly higher sensitivity and image resolution compared with SR-µXRF measurements in bone. These improvements reveal tissue-specific distribution patterns of tungsten and zinc in bone, not observed using SR-µXRF. We conclude that probing elemental distribution in bone is best achieved using LA-ICP-MS, though SR-µXRF retains the advantage of being a non-destructive method with the capability of being paired with X-ray techniques, which determine speciation in situ. Since tungsten is an emerging contaminant recently found to accumulate in bone, accurately determining its distribution and speciation in situ is essential for directing toxicological studies and informing treatment regimes. Graphical abstract Tungsten and zinc localization and uptake in mouse femurs were imaged by synchrotron radiation, left, and by laser ablation ICP-MS, right. The increased resolution of the LA-ICP-MS technique resolves the problem of the overlap in tungsten's L-edge and zinc's K-edge.

Tungsten in Washington State surface waters.

At high concentrations, tungsten can be toxic to humans, animals, and the environment, though little is known about natural, aqueous tungsten in surface waters. To improve understanding and develop a model predicting tungsten concentrations, we collected water and sediment from 77 water bodies in 20 watersheds in Washington State, USA. We found aqueous tungsten concentrations spanning two orders of magnitude (10.3 ng L-1 - 2.05 µg L-1) with average tungsten concentrations in both water and sediments more than two-fold higher in watersheds with tungsten-bearing underlying rock types (average: 0.217 µg L-1, 0.669 mg kg-1; range: 0.010-2.05 µg L-1, 0.0713-4.691 mg kg-1 for surface waters and sediments, respectively) than in watersheds without such underlying geology (average: 0.068 µg L-1, 0.352 mg kg-1; range: 0.010-0.211 µg L-1, 0.0349-2.399 mg kg-1 for surface waters and sediments, respectively). Aqueous concentrations of tungsten significantly correlated with beryllium (Be) and copper (Cu) (R2 = 0.31, 0.41, respectively) and a multiple linear regression model using Be and Cu explained 65% of the variance in measured aqueous tungsten concentrations. Applying this model to existing Be and Cu data from 19 sites across the Pacific Northwest resulted in predicted tungsten concentrations ranging from 0.116 to 0.458 µg L-1. These predicted concentrations along with our measured concentrations indicate none of these sites were close to the drinking water standard for tungsten set by the former Soviet Union-the only country so far to set limits for tungsten in drinking water (50 µg L-1).

[Determination of tungsten and insoluble compounds in the air of workplace by ICP-OES].

Objective: To establish the method for determination of tungsten and insoluble compounds in the air of workplace by inductively coupled plasma optical emission spectrometry (ICP-OES) . Methods: The tungsten and insoluble compounds were digested by microwave digestion apparatus using nitric acid and hydrofluoric acid, detected by ICP-OES. Results: The linearity of tungsten and insoluble compounds (as tungsten) were good at the range of 0.16-100.0 µg/ml, the minimum quantitation concentration was 0.11 mg/m(3), the recovery was ranged from 81.9%-97.1%, the RSD of intra-and inter-batch precision were 0.5%-2.5% and 1.2%-4.4%, respectively. Conclusion: The determination method meet the requirement of analysis and apply to the determination of tungsten and insoluble compounds in the air of workplace.

APPLICATION OF THE EUROPEAN PROTOCOL IN THE EVALUATION OF DIGITAL MAMMOGRAPHY UNITS WITH TUNGSTEN TARGET TUBES.

The performance of the first direct digital mammography unit in Gozo General Hospital, the Hologic Selenia Dimensions 2D, was assessed by applying the European Protocol for quality control in mammography screening. This system employs a Tungsten anode in association with a Rhodium or Silver filter, depending on the compressed breast thickness. The objective of this article was to apply the European Protocol in the evaluation of this system in terms of dose, image quality and detector performance and determine whether this system is suitable for use in the national breast-screening program.

Mobility of multiple heavy metalloids in contaminated soil under various redox conditions: Effects of iron sulfide presence and phosphate competition.

The mobility of heavy metalloids including As, Sb, Mo, W, and Cr in soil was investigated under both reducing and oxidizing conditions. The effects of soil mineralogy and the presence of competitive anions were studied as important factors affecting the mobility of these contaminants. Batch experiments conducted with the addition of oxidized and fresh FeS exhibited enhanced sorption rates for As and W under oxidizing conditions, and for Mo under reducing conditions. The inhibitory effect of phosphate on the sorption rates was most apparent for As and Mo under both oxidizing and reducing conditions, while only a small phosphate effect was observed for Sb and W. For Sb and W mobility, pH was determined to be the most important controlling factor. The results of long-term batch experiments revealed that differences in the mobility of metalloids, particularly As, were also influenced by microbial activity in the oxidizing and reducing conditions.

Assessing potential release tendency of As, Mo and W in the tributary sediments of the Three Gorges Reservoir, China.

As the largest man-made reservoir in China, the Three Gorges Reservoir (TGR) has significant influence on national drinking water safety. The geochemical behavior of trace elements at the sediment-water interface (SWI) is still unknown. The mobilization characteristics of trace elements (As, Mo and W)-determined by diffusive gradients in thin films (DGT)-were studied to quantitatively calculate the release trends in the SWI in three typical tributaries and the mainstream of the TGR in the summer. The results showed that concentrations of DGT-labile As, Mo and W in the overlying water and sediment cores showed significant variations in the ranges of 0.05-50.90, 0.30-1.63 and 0.01-0.42µgL-1, respectively. The apparent net diffusive fluxes were significantly positive in most sampling sites (77.8% for As, 88.8% for Mo and 66.6% for W), suggesting that the sediment was the source of these three elements. It was noteworthy that the maximum net diffusive fluxes of As and W were found in the upstream of Meixi tributary, which may be attributed to anthropogenic activities. In addition, As, Mo and W may be incorporated in Fe and Mn oxyhydroxides and these three elements simultaneously remobilized with Fe and Mn.

Mortality Among Hardmetal Production Workers: Swedish Measurement Data and Exposure Assessment.

BACKGROUND: Mortality pattern was determined in a cohort of 16,999 white and blue-collar workers in the Swedish hardmetal industry. Exposure assessment for cobalt is presented. METHODS: A historical database (1970 to 2012) of personal and area measurements of cobalt, tungsten, and nickel in the Swedish hardmetal industry was created. Log linear and exponential modeling of cobalt concentrations based on time period, job, and site was performed, and cumulative and mean exposures were calculated. RESULTS: Some 37% of the personal cobalt measurements exceeded 0.02 mg/m, mostly for powder production, pressing, and shaping. The log linear regression showed statistical differences (P < 0.05) between sites, time periods, and jobs. Some 1.6% of the cobalt cumulative exposures for blue-collar workers exceeded 0.4 mg/m years. CONCLUSION: Low levels of cumulative and mean exposures were determined.

[Determination of tungsten and cobalt in the air of workplace by ICP-OES].

Objective: To establish the inductively coupled plasma optical emission spectrometry (ICP-OES) method for determination of cobalt and tungsten in the air of workplace. Methods: The cobalt and tungsten were collected by filter membrane and then digested by nitric acid, inductively coupled plasma optical emission spectrometry (ICP-OES) was used for the detection of cobalt and tungsten. Results: The linearity of tungsten was good at the range of 0.01-1 000 µg/ml with a correlation coefficient of 0.999 9, the LOD and LOQ were 0.006 7 µg/ml and 0.022 µg/ml, respectively. The recovery was ranged from 98%-101%, the RSD of intra-and inter-batch precision were 1.1%-3.0% and 2.1%-3.8%, respectively. The linearity of cobalt was good at the range of 0.01-100 µg/ml with a correlation coefficient of 0.999 9, the LOD and LOQ were 0.001 2 µg/ml and 0.044 µg/ml, respectively. The recovery was ranged from 95%-97%, the RSD of intra-and inter-batch precision were 1.1%-2.4% and 1.1%-2.9%, respectively. The sampling efficiency of tungsten and cobalt were higher than 94%. Conclusion: The linear range, sensitivity and precision of the method was suitable for the detection of tungsten and cobalt in the air of workplace.

Mortality Among Hardmetal Production Workers: Occupational Exposures.

OBJECTIVE: To generate quantitative exposure estimates for use in retrospective occupational cohort mortality studies of the hardmetal industry. METHODS: Job-exposure matrices (JEMs) were constructed for cobalt, tungsten, and nickel over the time period 1952 to 2014. The JEMs consisted of job class categories, based on job titles and processes performed, and exposure estimates calculated from available company industrial hygiene measurements. RESULTS: Exposure intervals of one-half order magnitude were established for all three agents. Eight job classes had significantly decreasing time trends for cobalt exposure; no significant time trends were detected for tungsten or nickel exposures. CONCLUSIONS: The levels of exposures determined for this study were similar to or lower than those previously reported for the hardmetal industry during the 1952 to 2014 study period.

Biological monitoring of welders' exposure to chromium, molybdenum, tungsten and vanadium.

BACKGROUND: Welders are exposed to a number of metallic elements during work. Bioaccessability, that is important for element uptake, has been little studied. This study addresses bioaccessability and uptake of chromium (Cr), molybdenum (Mo), tungsten (W) and vanadium (V) among welders. METHODS: Bioaccessability of Cr, Mo, V and W was studied in airborne particulate matter collected by personal sampling of the workroom air among shipyard welders by using the lung lining fluid simulant Hatch solution. Associations between concentrations of Hatch soluble and non-soluble elements (Hatchsol and Hatchnon-sol) and concentrations of the four elements in whole blood, serum, blood cells and urine were studied. RESULTS: Air concentrations of the four elements were low. Only a small fraction of Cr, V and W was Hatchsol, while similar amounts of Mo were Hatchsol and Hatchnon-sol. Welders (N=70) had statistically significantly higher concentrations of all four elements in urine and serum when compared to referents (N=74). Highly statistically significant associations were observed between urinary W and Hatchsol W (p<0.001) and serum V and Hatchsol V (p<0.001), in particular when air samples collected the day before collection of biological samples were considered. CONCLUSIONS: Associations between Hatchsol elements in air and their biological concentrations were higher than when Hatchnon-sol concentrations were considered. Associations were generally higher when air samples collected the day before biological sampling were considered as compared to air samples collected two days before.

Elemental Composition of Plant Species from an Abandoned Tungsten Mining Area: Are They Useful for Biogeochemical Exploration and/or Phytoremediation Purposes?

We aimed to evaluate the elemental (W, Mo, Zn, Fe, Cu, Co, Bi, Mn, Cd, Cr, As) composition of some plant species spread around the abandoned tungsten mining area of Uludag Mountain. The plant species tested were Anthemis cretica and Trisetum flavescens which are grown in this area and they are pioneer species on these contaminated sites. W levels in soils were found up to 1378.6 ± 672.3 mg/kg dry weight in contaminated areas. The leaf W contents of the selected plant species were found 41.1 ± 24.4 and 31.1 ± 15.5 mg/kg dry weight for A. cretica and T. flavescens, respectively. Our results indicate that the elemental composition of species changed by the increased tungsten and some element concentrations in soil without detrimental effect. So, these species can be useful tungsten removal and some elements from contaminated sites.

Influence of sediments and tungsten traces on the skeletal structure of Pseudodiploria: a reef building scleractinian coral from the Veracruz Reef System National Park, Mexico / Influencia de los sedimentos y trazas de tungsteno en la estructura del esqueleto de Pseudodiploria un coral escleractinio constructor de arrecifes del Parque Nacional Sistema Arrecifal Veracruzano, México

Abstract:Coral reefs are under intense conditions of stress caused by the anthropogenic activities in coastal areas and the increase of human population. Water effluents from urban and industrial areas carry large amounts of sediments and pollutants affecting corals populations, inducing bioerosion, increasing diseases and promoting the development of algae that compete for space with corals. In the Veracruz Reef System National Park (VRSNP) coral reefs are strongly affected by human activities carried out in the area. Gallega and Galleguilla reefs are among the most affected by wastewater discharges from the industrial (petrochemical and metallurgical) and urban areas in their vicinity. To assess the potential impact of this contamination on corals in the VRSNP, a chemical composition and morphology study of 76 Pseudodiploria colonies collected in reefs Gallega, Galleguilla, Isla Verde and Isla de Enmedio, was performed. Fragments of ~10 cm2 were collected and boric acid at 0.5 % was used to remove tissue from the skeleton; once clean, the morphology of each sample was determined with a scanning electron microscope (SEM). Subsequently, to test the chemical composition, an energy dispersion spectroscopy of X-ray chemical microanalysis (EDSX) was performed in the SEM. We found that corals from Gallega and Galleguilla reefs, located closer to human populations, presented high levels of tungsten and the skeleton exhibited multiple perforations. In contrast, corals from the farthest offshore reefs (Isla Verde and Isla de Enmedio) exhibited lower levels of tungsten and fewer perforations in their skeleton. These results demonstrated that anthropogenic activities in the NPVRS are affecting corals skeleton, highly damaging and promoting their bioerosion. The presence of traces of tungsten in the skeleton of corals is an evidence of the damage that waste discharges are causing to coral reefs. Discharges of large amounts of contaminants promoted the growth of harmful species that grow and develop into the corals skeleton, causing its bioerosion, and making them susceptible to disease and physical damage. This study is the first evidence of the effects of contamination on these species; therefore, further studies are necessary to determine the impact of pollution on their biology and survival. Rev. Biol. Trop. 64 (3): 1077-1089. Epub 2016 September 01.

ResumenLos arrecifes de coral se encuentran bajo condiciones intensas de estrés causado por las actividades antropogénicas y el incremento de las poblaciones humanas en las zonas costeras. Las descargas de aguas de origen urbano e industrial transportan sedimentos y contaminantes que afectan a las poblaciones de corales, induciendo la bioerosion, el aumento de enfermedades en los corales y promueven el desarrollo de algas que compiten por espacio con los corales. En el Parque Nacional Sistema Arrecifal Veracruzano (NPVRS) los arrecifes de coral son afectados fuertemente por las actividades humanas que se llevan a cabo en la zona. Los arrecifes Gallega y Galleguilla son de los más afectados por las descargas de aguas residuales provenientes de la industria (petroquímica y metalúrgica) y de áreas urbanas que desembocan sus aguas en las proximidades de los arrecifes. Para evaluar el posible impacto de las descargas de aguas en los corales del NPVRS, se realizó un estudio de la composición química y morfología de 76 colonias de Pseudodiploria en los arrecifes Gallega, Galleguilla, Isla Verde e Isla de Enmedio. Se recolectaron fragmentos de ~10 cm2, el tejido del esqueleto fue removido utilizando ácido bórico al 0.5 %. Una vez limpia la muestra, la morfología fue analizada con un microscopio electrónico de barrido (SEM), posteriormente, para analizar la composición química de las muestras, realizamos una espectroscopia de dispersión de energía o micro-análisis químico de rayos X (EDSX) en el SEM. Encontramos que los corales de los arrecifes Gallega y Galleguilla que se encuentran ubicados cerca de poblaciones humanas, presentan altos niveles de tungsteno y el esqueleto exhibe múltiples agujeros. En contraste, los corales de los arrecifes más lejanos (Isla Verde e Isla de En medio) mostraron niveles más bajos de tungsteno y un menor número de agujeros en su esqueleto. Nuestros resultados demuestran que las actividades antropogénicas en el NPVRS, están afectando el esqueleto de los corales y promueven la bioerosión. Las descargas de grandes cantidades de contaminantes hacia las zonas costeras, promueven el crecimiento de especies dañinas que crecen y se desarrollan dentro del esqueleto de los corales, causando bioerosión del esqueleto, haciéndolos susceptibles a enfermedades y daños físicos. Debido a que este estudio es la primera evidencia de los efectos de la contaminación sobre esta especie de corales, son necesarios más estudios para determinar el impacto de la contaminación sobre su biología y la supervivencia de los corales.