Mine waste (MW) in historical mercury (Hg) mining areas continuously emits Hg into local environment, including aquatic ecosystems. Tracing Hg migration process from MW and determining its relative contribution to Hg pollution is critical for understanding the environmental impact of MW remediation. In this study, we combined data of Hg concentration, speciation, and isotope to address this issue in the Wanshan Hg mining area in southwest China. We found that rainfall can elevate Hg concentrations in river water and control the partitioning and transport of Hg in karst fissure zones through changing the hydrological conditions. A consistently large offset of δHg (1.24‰) was observed between dissolved Hg (DHg) and particulate Hg (PHg) in surface water during the low-flow period (LFP), which may have been related to the relatively stable hydrologic conditions and unique geological background (karst fissure zones) of the karst region (KR). Results from the ternary Hg isotopic mixing model showed that, despite an order of magnitude reduction in Hg concentration and flux in river water after remediation, the remediated MW is still a significant source of Hg pollution to local aquatic ecosystems, accounting for 49.3 ± 11.9% and 37.8 ± 11.8% of river DHg in high flow period (HFP) and LFP, respectively. This study provides new insights into Hg migration and transportation in aquatic ecosystem and pollution source apportionment in Hg polluted area, which can be used for making polices for future remediation actions.
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http://dx.doi.org/10.1016/j.watres.2023.119592 | DOI Listing |
Biomed Phys Eng Express
January 2025
Mindanao Radiation Physics Center, MSU-Iligan Institute of Technology, Andres Bonifacio Street Tibanga, Iligan City, Lanao Norte, 9200, PHILIPPINES.
To accurately model and validate the 6 MV Elekta Compactlinear accelerator using the Geant4 Application for Tomographic Emission (GATE). In particular, this study focuses on the precise calibration and validation of critical parameters, including jaw collimator positioning, electron source nominal energy, flattening filter geometry, and electron source spot size, which are often not provided in technical documentation. Methods: Simulation of the Elekta Compact6 MV linear accelerator was performed using the Geant4 Application for Tomographic Emission (GATE) v.
View Article and Find Full Text PDFLangmuir
January 2025
Centre for Energy (M473), The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
The mechanisms of NO reduction by CO over nitrogen-doped graphene (N-graphene)-supported single-atom Ni catalysts in the presence of O, HO, CO, and SO have been studied via density functional theory (DFT) modeling. The catalyst is represented by a single Ni atom bonded to four N atoms on N-graphene. Several alternative reaction pathways, including adsorption of NO on the Ni site, direct reduction of NO by CO, decomposition of NO to NO followed by reduction of NO to N, formation of active oxygen radical O*, and reduction of O* by CO, were hypothesized and the energy barrier corresponding to each of the reaction steps was calculated using DFT.
View Article and Find Full Text PDFLangmuir
January 2025
Department of Chemistry, The University of Utah, Salt Lake City, Utah 84112, United States.
Slip flow, a fluid flow enhanced in comparison to that calculated using continuum equations, has been reported for many nanopores, mostly those with hydrophobic surfaces. We investigated the flow of water, hexane, and methanol through hydrophilic nanopores in silica colloidal crystals. Three silica sphere sizes were used to prepare the crystals: 150 ± 30, 500 ± 40, and 1500 ± 100 nm.
View Article and Find Full Text PDFBackground: It is generally accepted that the greater palatine nerve and artery supply the palatal mucosa, gingiva, and glands, but not the bone or tooth adjacent to those tissues. When the bony palate is observed closely, multiple small foramina are seen on the palatal surface of the alveolar process. The authors hypothesized that the greater palatine nerve and artery might supply the maxillary teeth via the foramina on the palatal surface of the alveolar process and the superior alveolar nerve and artery.
View Article and Find Full Text PDFSoft Matter
January 2025
Center of Excellence in Energy Conversion (CEEC), Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran.
Recent progress in digital microfluidics has revealed the distinct advantages of liquid marbles, such as minimal surface friction, reduced evaporation rates, and non-wettability compared to uncoated droplets. This study provides a comprehensive examination of an innovative technique for the precise, contamination-free manipulation of non-magnetic water liquid marbles (WLMs) carried by a ferrofluid liquid marble (FLM) under the control of direct current (DC) and pulse-width modulation (PWM) magnetic fields. The concept relies on the phenomenon in which an FLM and WLMs form a shared meniscus when placed together on a water surface, causing the WLMs to closely track the magnetically actuated FLM.
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