Time filter

Source Type

Umeå, Sweden

Kumar R.,Orebro University | Kumar R.,Tomsk State University | Pradhan A.,Orebro University | Khan F.A.,Orebro University | And 4 more authors.

Metals are essential for many physiological processes and are ubiquitously present in the environment. However, high metal concentrations can be harmful to organisms and lead to physiological stress and diseases. The accumulation of transition metals in the environment due to either natural processes or anthropogenic activities such as mining results in the contamination of water and soil environments. The present study used Caenorhabditis elegans to evaluate gene expression as an indicator of physiological response, following exposure to water collected from three different locations downstream of a Swedish mining site and a lab reconstituted metal mixture. Our results indicated that the reconstituted metal mixture exerted a direct stress response in C. elegans whereas the environmental waters elicited either a diminished or abrogated response. This suggests that it is not sufficient to use the biological effects observed from laboratory mixtures to extrapolate the effects observed in complex aquatic environments and apply this to risk assessment and intervention. © 2015 Kumar et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Source

Saiang C.,Lulea University of Technology | Miskovsky K.,Lulea University of Technology | Miskovsky K.,Envix Nord AB
Harmonising Rock Engineering and the Environment - Proceedings of the 12th ISRM International Congress on Rock Mechanics

A laboratory study was conducted to study the effect of heat on the mechanical properties of diabase, granite and quartzitic schist at temperatures of 400°C, 750°C and 1100°C. Unheated samples were also studied. The reasoning behind this study was to understand the effect of elevated temperatures on the rock mass, such as in the event of a fire in a rock tunnel. Samples from the aforementioned rock types were heat treated at temperatures shown above, cooled slowly to room temperature and then subjected to uniaxial compression and Brazilian tests. Thin sections were extracted from the heat treated samples for microscopic analyses, which assisted in explaining the reasons for the mechanical behaviour observed from the mechanical test results. The uniaxial compression test showed that the strength of the rock specimens increased by 6% for granite to 29% for diabase at 400°C when compared to the UCS values of the unheated specimens. From 750°C to 1100°C the decay in the strength was very rapid. From the microscopic analyses it was concluded that the increase in the strength of the rock specimens at 400°C is attributed to the initial reaction of the rock forming minerals, hence the rock specimens were less brittle but more plastic. The rapid drop in the strength from 750°C to 1100°C is attributed to the mineralogical changes, micro-cracking and dehydration due to the loss of crystal bound water. At 1100°C the rocks were highly friable and crumbled very easily when tested mechanically. The effect of mineralogical changes was obvious in diabase where the physical appearance of the samples mimicked that of natural iron, which is believed to be due to the alteration of pyroxene. The result was an increase in strength by 29% at 400°C compared to the unheated specimens. Even at 750°C the strength was slightly higher than unheated specimens. In summary; the mechanical behaviour of the rock specimens depended on the temperature level and the mineralogical and physical changes that occur at that temperature. © 2012 Taylor & Francis Group, London. Source

Newton S.,University of Stockholm | Bidleman T.,Umea University | Bergknut M.,Umea University | Bergknut M.,Envix Nord AB | And 4 more authors.
Environmental Sciences: Processes and Impacts

Bimonthly bulk atmospheric deposition samples (precipitation + dry particle) were taken for one year at an arctic (Abisko, 68°20′ N, 19°03′ E) and a sub-arctic (Krycklan 64°14′ N, 19°46′ E) location in northern Sweden using Amberlite IRA-743 as an absorbent for hydrophobic pollutants. The samples were analyzed by gas chromatography-high resolution mass spectrometry (GC-HRMS) for polychlorinated biphenyls (PCBs), legacy organochlorine pesticides (OCPs = hexachlorocyclohexanes and chlordane-related compounds), polybrominated diphenyl ethers (PBDEs) and emerging chemicals. Higher deposition rates of most compounds were observed at the more northern site despite its receiving less precipitation and being more remote. HCHs and PCBs made up the bulk of the total deposition at both sites. Five emerging chemicals were detected: the current-use pesticides trifluralin and chlorothalonil; and non-BDE flame retardants 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), and Dechlorane Plus (DP). A decrease in the fraction of the anti isomer of DP was observed at the arctic site, indicating isomer-selective degradation or isomerization during long range transport. Air parcel back trajectories revealed a greater influence from air originating over the ocean at the more northern site. The differences in these air sources were reflected in higher ∑HCH to ∑PCB ratios compared to the more southern site, as HCHs are related to volatilization from the ocean and Abisko is located <100 km from the Norwegian coast, while PCBs are emitted from continental sources. This journal is © The Royal Society of Chemistry 2014. Source

Ragnvaldsson D.,Envix Nord AB | Bergknut M.,Envix Nord AB | Lewis J.,Envix Nord AB | Drotz S.,Metsa Board Sweden AB | And 3 more authors.
Environmental Chemistry Letters

When exposed to the weather, sulfidic minerals release sulfuric acid, metals and metalloids. This leachate can devastate nearby ecosystems for centuries. This article reports a novel barrier system based on green liquor dregs that reduces acid generation, is inexpensive, and is practical for implementation at operational mines. Two waste rock piles were constructed. One pile was left open to the atmosphere, and the other was sealed with green liquor dregs and partially capped with a polyethylene liner. This test was designed in collaboration with personnel from Boliden Mineral AB, a Swedish mining company in order to ensure that the results would be practical to implement at an operational mine. Leachate flow and chemistry were monitored in both piles over a period of 12 months. Effluent volume was 40 % lower in the test pile, while thirteen of the twenty elements assessed showed average concentrations that were 50 % lower in the test pile than in the control pile. For the most environmentally toxic elements As, Cd, Pb and Hg, reductions were even more significant, ranging between 67 and 87 %. These positive results are hypothesized to be primarily due to the chemical and physical characteristics of the green liquor dregs. The novelty of this result is that it is the first barrier system that fulfills the multiple needs of the Swedish mining industry: It is effective in reducing acid mine drainage while remaining both economical and practical. No other barrier system meets these requirements. © 2014 Springer International Publishing Switzerland. Source

Discover hidden collaborations