Contamination level and spatial distribution of heavy metals in water and sediments of El Guájaro Reservoir, Colombia

Heavy metals have become a subject of special concern worldwide, mainly due to high persistence in the environment, toxicity, biogeochemical recycling and ecological risk. Therefore, the objective of this investigation was to analyze the spatial–temporal distribution of heavy metals in water and sediments to determine the environmental status of El Guájaro Reservoir, where such studies have not been developed. Two measurement campaigns (dry and wet period) were carried out and eight sampling stations were selected. A comparison of water and sediment quality parameters with existing national and international regulations was done. Also, heavy metal distribution maps were generated, and the geoaccumulation index was calculated to identify sources and sediments contamination level. Based on the obtained results, agriculture and mining activities are the main causes of the reservoir contamination. This metals levels could be a potential risk for the aquatic life and the populations that are supplied from this water body

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) 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.Financial support from the Spanish Ministry of Science and Innovation through Project PGC 2018–097961-B-I00 is acknowledged. Laura Suárez-Criado is grateful to the Principality of Asturias, Spain, for their financial support through the Severo Ochoa scholarship ref. BP19-131. The authors would also like to acknowledge the Spanish National Research Council (CSIC) through project I–COOP+2021-COOPA20490 and the Programa Iberoamericano de Ciencia y Tecnología para el Desarrollo (CYTED), for financing the MercuRed Network (420RT0007).Peer reviewe

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. © 2020 Elsevier B.V

Hg, Cu, Pb, Cd, and Zn accumulation in macrophytes growing in tropical wetlands

The concentrations of Hg, Cu, Pb, Cd, and Zn accumulated by regional macrophytes were investigated in three tropical wetlands in Colombia. The studied wetlands presented different degrees of metal contamination. Cu and Zn presented the highest concentrations in sediment. Metal accumulation by plants differed among species, sites, and tissues. Metals accumulated in macrophytes were mostly accumulated in root tissues, suggesting an exclusion strategy for metal tolerance. An exception was Hg, which was accumulated mainly in leaves. The ranges of mean metal concentrations were 0.035-0.953 mg g -1 Hg, 6.5-250.3 mg g -1 Cu, 0.059-0.245 mg g -1 Pb, 0.004-0.066 mg g -1 Cd, and 31.8-363.1 mg g -1 Zn in roots and 0.033-0.888 mg g -1 Hg, 2.2-70.7 mg g -1 Cu, 0.005-0.086 mg g -1 Pb, 0.001-0.03 mg g -1 Cd, and 12.6-140.4 mg g -1 Zn in leaves. The scarce correlations registered between metal concentration in sediment and plant tissues indicate that metal concentrations in plants depend on several factors rather than on sediment concentration only. However, when Cu and Zn sediment concentrations increased, these metal concentrations in tissues also increased in Eichhornia crassipes, Ludwigia helminthorriza, and Polygonum punctatum. These species could be proposed as Cu and Zn phytoremediators. Even though macrophytes are important metal accumulators in wetlands, sediment is the main metal compartment due to the fact that its total mass is greater than the corresponding plant biomass in a given area.Fil: Núñez, S. E. Romero. Universidad de Córdoba; ColombiaFil: Negrete, J. L. Marrugo. Universidad de Córdoba; ColombiaFil: Rios, J. E. Arias. Universidad de Córdoba; ColombiaFil: Hadad, Hernán Ricardo. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Laboratorio de Química Analítica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Maine, Maria Alejandra. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Laboratorio de Química Analítica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin