Rapid monitoring of mercury in air from an organic chemical factory in China using a portable mercury analyzer

Remediation of chromium and mercury polluted calcareous soils using nanoparticles: Sorption -desorption kinetics, speciation and fractionation

Stabilization is an emerging technology for the cost-effective remediation of heavy metals polluted soils. To evaluate the potential of water treatment residual nanoparticles (nWTR) in reducing Hg and Cr mobility in contaminated calcareous soil, sorption-desorption kinetics; speciation and fractionation experiments were performed. Application of nWTR strongly enhanced Cr and Hg sorbed in the calcareous soil, whereas the released amount of both metals through 6 successive desorption steps dramatically decreased. The power function model best described the desorption kinetic data of Cr and Hg from nWTR amended and non-amended calcareous soil. Fractionation experiment data demonstrated that nWTR amendment significantly increased metals concentration in the residual fraction (RS) and simultaneously decreased the more accessible forms of Hg and Cr. Addition of nWTR at a rate of 0.3% to the contaminated calcareous soil significantly increased Hg and Cr in the RS fraction from 69.27% and52.62% to 93.89% and 90.05% respectively. Additionally, the formation of stable Hg and Cr species such as Hg(OH)₂ amor, CrSO₄. xH₂O and Cr(OH)₂) were increased as a result of nWTR application. These findings jointly indicate the enhancement of Hg and Cr immobilization in the nWTR amended calcareous soil. FTIR spectroscopy analysis indicated the contribution of OH group and Al-O-Si of nWTR in Hg and Cr sorption process and suggests chemo-sorption reaction between both metals and the nWTR surface functional groups. Overall, the final results confirm the strong capability of nWTR application in reducing Hg and Cr risks in highly contaminated sites of the calcareous soil.

Mercury species in formerly contaminated soils and released soil gases

Total mercury (T-Hg), elemental mercury (Hg⁰), methylmercury (MeHg⁺), phenylmercury (PhHg⁺), and gaseous elemental mercury (GEM) species were determined in soils formerly contaminated by different processes from two sites in the Czech Republic. Analytical methods involved atomic absorption spectrometry (AAS) using a single-purpose Advanced Mercury Analyser AMA-254 and radiochemical neutron activation analysis (RNAA) for T-Hg determination, a thermal desorption method was used for Hg⁰ determination, gas chromatography coupled with atomic fluorescence spectrometry (GC-AFS) was employed for assay of MeHg⁺ and PhHg⁺, while GEM measurement was carried out using a portable Zeeman-AAS device Lumex RA-915⁺. The first sampling site was in the surroundings of a former PhHgCl-based fungicide processing plant next to Příbram (central Bohemia). Although the use of Hg-based fungicides as seed mordant have been banned, and their production stopped at the end of 1980's, highly elevated Hg contents in soil are still observed in the vicinity of the former plant, reaching T-Hg values >13mgkg^-1. The second sampling site was an abandoned mining area named Jedová hora Hill near Hořovice (central Bohemia), where cinnabar (HgS) was occasionally mined as by-product of Fe ores hematite and siderite. Mining activities have been stopped here in 1857. Very high contents of T-Hg are still found at this site, up to 144mgkg^-1. In most cases we found a statistically significant correlation between T-Hg and Hg⁰ values regardless of the pollution source. On the contrary, insignificant correlation was observed neither between T-Hg and GEM values, nor between GEM and Hg⁰. Concentrations of the investigated organomercury species were above a limit of detection (LOD) only in the most contaminated samples, where their levels were about two to three orders of magnitude lower compared to those of T-Hg.

A compilation of field surveys on gaseous elemental mercury (GEM) from contrasting environmental settings in Europe, South America, South Africa and China: separating fads from facts

Mercury is transported globally in the atmosphere mostly in gaseous elemental form (GEM, [Formula: see text]), but still few worldwide studies taking into account different and contrasted environmental settings are available in a single publication. This work presents and discusses data from Argentina, Bolivia, Bosnia and Herzegovina, Brazil, Chile, China, Croatia, Finland, Italy, Russia, South Africa, Spain, Slovenia and Venezuela. We classified the information in four groups: (1) mining districts where this contaminant poses or has posed a risk for human populations and/or ecosystems; (2) cities, where the concentration of atmospheric mercury could be higher than normal due to the burning of fossil fuels and industrial activities; (3) areas with natural emissions from volcanoes; and (4) pristine areas where no anthropogenic influence was apparent. All the surveys were performed using portable LUMEX RA-915 series atomic absorption spectrometers. The results for cities fall within a low GEM concentration range that rarely exceeds 30 ng m(-3), that is, 6.6 times lower than the restrictive ATSDR threshold (200 ng m(-3)) for chronic exposure to this pollutant. We also observed this behavior in the former mercury mining districts, where few data were above 200 ng m(-3). We noted that high concentrations of GEM are localized phenomena that fade away in short distances. However, this does not imply that they do not pose a risk for those working in close proximity to the source. This is the case of the artisanal gold miners that heat the Au-Hg amalgam to vaporize mercury. In this respect, while GEM can be truly regarded as a hazard, because of possible physical-chemical transformations into other species, it is only under these localized conditions, implying exposure to high GEM concentrations, which it becomes a direct risk for humans.