Mercury Pollution Assessment of Mining Wastes and Soils From Former Silver Amalgamation Area in North-Central Mexico

Abstract

Mining wastes and soils from Cedral, San Luis Potosí, Mexico, were studied to assess mercury (Hg) pollution in areas of historical silver (Ag) amalgamation and in areas where amalgamation mining wastes were recently reprocessed for Hg and Ag recovery. The total, soluble and bioaccessible Hg concentrations from eight mining waste and nine soil cores were determined at varying depths, which fluctuated from the surface up to 1.0 m depth. The total Hg concentrations in the mining wastes samples ranged from 8 to 548 mg/kg. The total Hg concentrations in the soil samples were lower (1 to 116 mg/kg) than those in the mining wastes. Eighty percent of the soil samples exceeded the maximum permissible limit for residential soils according to the Mexican regulations, demonstrating the impacts of the amalgamation process in Cedral. The soluble Hg concentrations were low, from 0.009 to 0.32 mg/kg in the mining wastes, and from 0.003 to 0.02 mg/kg in soils. The latter represents 0.007 % to 0.54 % and < 0.03 % of total Hg, from mining wastes and soils, respectively, indicating low aqueous Hg transport during rainfall events. The bioaccessible Hg concentrations in the mining waste samples (0.1 to 60 mg/kg) and soil samples (0.1 to 17 mg/kg), suggested that humans could be exposed to this toxic element through the accidental ingestion of mining wastes and soil particles. Although the total Hg concentrations in the mining wastes decreased after reprocessing, the soluble and bioaccessible Hg concentrations increased.Palabras clave: beneficio de patio, jales, reprocesamiento, solubilidad, bioaccesibilidad RESUMENSe estudiaron residuos mineros y suelos de Cedral, San Luis Potosí, México, para evaluar la contaminación por mercurio (Hg) en áreas de amalgamación histórica de plata (Ag) y de reprocesamiento reciente de residuos de amalgamación para la recuperación de Hg y Ag. Se obtuvieron ocho perfiles de hasta 1 m de profundidad de depósitos de 656residuos mineros y nueve de suelo, de los cuales se recolectaron muestras a diferentes profundidades para la determinación de concentraciones totales, solubles y bioaccesibles de Hg. Las concentraciones totales de Hg en residuos mineros variaron entre 8 y 548 mg/kg, mientras que en suelos las concentraciones se presentaron en un rango de entre 1 y 116 mg/kg. Se encontró que el 80 % de las muestras de suelo analizadas superaron el límite máximo permisible de Hg para suelo de uso residencial establecido en la normatividad mexicana, lo que demuestra el severo impacto de la amalgamación y del reprocesamiento de jales de amalgamación en Cedral. Con relación a las concentraciones solubles de Hg, en las muestras de residuos se obtuvieron de 0.009 a 0.32 mg/kg y de 0.003 a 0.02 mg/kg para suelos, lo que representa de 0.007 % a 0.54 % y < 0.03 % del total de Hg contenido en residuos mineros y suelos, respectivamente. Esto indica un bajo potencial de transporte de especies solubles de Hg durante eventos de lluvia. Finalmente, las concentraciones de Hg bioaccesible obtenidas en el estudio (0.1...

Mercury in Blood of Children Exposed to Historical Residues from Metallurgical Activity

“…To achieve the objective of this study, Hg concentration data of representative sources as tailings samples and their associated impacted soils, previously reported by part of our research team (Leura-Vicencio 2017;Leura-Vicencio et al 2017), were assessed. In addition, soil samples from the entire urban area of Cedral previously reported by Morton-Bermea et al (2015) were also considered.…”

“…Mercury concentration data for the metallurgical residues and soil samples from Cedral were obtained from previous work reported by our research team (Leura-Vicencio 2017;Leura-Vicencio et al 2017). For our study, the results of the uppermost sections (0-10 cm) of three sampling points of reprocessed material from the processing facilities from Jesús María were selected.…”

“…Hg concentration data from 10 top-soil samples (0-15 cm) collected from both older mineral processing facilities and their immediate surroundings were also considered; all of them located on the west side of the urban perimeter of Cedral. Preparation and analysis of these samples are described in Leura-Vicencio (2017) and Leura-Vicencio et al (2017). The quality assurance of the tailing and soil samples data reported by Leura-Viencio et al (2017) was checked with the standard reference material (SRM) 2710a "Montana Soil" obtained from the National Institute of Science and Technology, USA.…”

“…Low Hg concentration (below 0.7%) of Me-Hg and/or HgCl 2 (soluble fraction) was also identified. Leura-Vicencio et al (2017) provided information on Hg concentrations in mining wastes and soils from the study area. The study concluded that reprocessed tailing material has a higher Hg solubility than non-reprocessed material.…”

Biosorption of mercury (II) from aqueous solution onto biomass of Aspergillus niger

“…The total concentrations of Hg in mining residues varied between 8 and 548 mg/kg, while in soils the concentrations were in a range of between 1 and 116 mg/kg. It was found that 80% of the soil samples analyzed exceeded the maximum permissible limit of Hg for land for residential use established in Mexican regulations (Leura Vicencio et. al., 2017).…”