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"Pollution Probe History."
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Metal(loid)s and their bioaccessibility in urban soils from residential areas of a medieval mining town
In historic mining towns, where mining activities were abandoned many decades or even centuries ago, legacy contaminations can be remobilized and redispersed, representing a threat for the environment and human health. This study focuses on urban soils (
n
= 19) in the town of Jihlava, the Czech Republic, one of the medieval centers of silver mining in central Europe. The basic geochemical characterization of the soils was combined with mineralogical investigations to understand the solid speciation of the metal(loid) contaminants, oral bioaccessibility tests, and exposure assessment. The total concentrations of the metal(loid)s in the original soils were not excessively high (up to 45.8 mg As/kg, 19.2 mg Cd/kg; 205 mg Cr/kg; 91.8 mg Cu/kg, 163 mg Pb/kg, 253 mg V/kg, 262 mg Zn/kg), although, in some cases, they exceeded the regulatory guidelines for agricultural and/or residential soils. A substantial increase in the metal(loid)s contents was confirmed for the < 48-µm soil fraction that was later used for the bioaccessibility tests. Scanning electron microscopy and the electron microprobe showed that ore-derived primary sulfides were rare in the studied soils. Still, hydrous ferric oxides rich in Cu, Pb and Zn and fragments of metallurgical slags composed of metal-containing glass and silicates (olivine) were prone to dissolution during extraction in a simulated gastric fluid (SGF, glycine solution acidified to pH 1.5 by HCl). The maximum bioaccessible concentrations corresponded to 4.69 mg As/kg, 1.75 mg Cd/kg, 2.02 mg Cr/kg, 20.3 mg Cu/kg, 81.6 mg Pb/kg, 16.2 mg V/kg, and 233 mg Zn/kg. Exposure estimates were carried out for children (10 kg) as a target group and a conservative soil ingestion rate (100 mg/d). However, the daily intake of all the studied contaminants was far below the tolerable limits. Our results show that the human health risk based on incidental soil ingestion in the studied area seems limited.
Journal Article
Pushing back the frontiers of mercury speciation using a combination of biomolecular and isotopic signatures: challenge and perspectives
Mercury (Hg) pollution is considered a major environmental problem due to the extreme toxicity of Hg. However, Hg metabolic pathways in biota remain elusive. An understanding of these pathways is crucial to elucidating the (eco)toxic effects of Hg and its biogeochemical cycle. The development of a new analytical methodology based on both speciation and natural isotopic fractionation represents a promising approach for metabolic studies of Hg and other metal(loid)s. Speciation provides valuable information about the reactivity and potential toxicity of metabolites, while the use of natural isotopic signature analysis adds a complementary dynamic dimension that allows the life history of the target element to be probed, the source of the target element (i.e., the source of pollution) to be identified, and reactions to be tracked. The resulting combined (bio)molecular and isotopic signature affords precious insight into the behavior of Hg in biota and Hg detoxification mechanisms. In the long term, this highly innovative methodology could be used in life and environmental science studies of metal(loid)s to push back the frontiers of our knowledge in this field. This paper summarizes the current status of the application of Hg speciation and the isotopic signature of Hg at the biomolecular level in living organisms, and discusses potential future uses of this combination of techniques.
Graphical Abstract
Application of Hg speciation and the isotopic signature of Hg to enhance our understanding of the roles of Hg in metabolic, toxicological, and environmental processes
Journal Article
Mars contamination fear could divert Curiosity rover
Four years into its travels across Mars, NASA's Curiosity rover faces an unexpected challenge: wending its way safely among dozens of dark streaks that could indicate water seeping from the red planet's hillsides. Although scientists might love to investigate the streaks at close range, strict international rules prohibit Curiosity from touching any part of Mars that could host liquid water, to prevent contamination.
Journal Article
Assessment of alternatives to environmental toxic formalin for DNA conservation in biological specimens
One essential step of museum and clinical specimen preservation is immersion in a fixative fluid to prevent degradation. Formalin is the most largely used fixative, but its benefit is balanced with its toxic and carcinogenic status. Moreover, because formalin-fixation impairs nucleic acids recovery and quality, current museum wet collections and formalin-fixed, paraffin-embedded clinical samples do not represent optimal tanks of molecular information. Our study has been developed to compare formalin to two alternative fixatives (RCL2® and ethanol) in a context of molecular exploitation. Based on a unique protocol, we created mammalian fixed collections, simulated the impact of time on preservation using an artificial ageing treatment and followed the evolution of specimens’ DNA quality. DNA extraction yield, purity, visual integrity and qualitative and quantitative ability to amplify the
Cox1
gene were assessed. Our results show that both RCL2 and ethanol exhibit better performances than formalin. They do not impair DNA extraction yield, and more importantly, DNA alteration is delayed over the preservation step. The use of RCL2 or ethanol as fixative in biological collections may insure a better exploitation of the genetic resources they propose.
Journal Article
Nova
Zero and infinity. These seemingly opposite, obvious and indispensable concepts are relatively recent human inventions. Discover the surprising story of how these key concepts that revolutionized mathematics came to be—not just once, but over and over again as different cultures invented and re-invented them across thousands of years.
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