Activity

Metal-insulator crossover throughout multilayered MoS2.

The bioaccessibility of As in soil, rather than its total concentration, is closely related to its potential risk. In this study, the in situ formation of amorphous Fe oxides was applied to As-contaminated soil to induce As-Fe coprecipitates that can withstand the gastric digestion condition of human beings. To promote the formation of Fe oxides, 2% ferric nitrate (w/w) and 30% water (v/w) were introduced, and the pH was adjusted to ~7. The chemical extractability of As in soil was determined using the solubility/bioavailability research consortium method and five-step sequential extraction. In situ formation of Fe oxides resulted in a remarkable increase in the As associated with amorphous Fe oxides, decreasing most of the exchangeable As (i.e., the sum of SO42- and PO43- extractable As), and thereby reducing the bioaccessibility of As. The types of association between As and Fe oxides were investigated using X-ray absorption spectroscopy analysis. Linear combination fit (LCF) analysis demonstrated that As bound to amorphous Fe oxides could exist as coprecipitates with ferrihydrite and schwertmannite after stabilization. The bioaccessibility of the coprecipitated As in soil further decreased as amorphous Fe oxides transformed to crystalline form with time, which was supported by the LCF results showing an increase of goethite in aged soil.Assessing polar bear (Ursus maritimus) immune function in relation to environmental stressors, including habitat change, nutritional stress, pathogen prevalence, and pollution, has been identified as critical for improved understanding of the species’ health. The objectives of this study were two-fold 1) to assess the role of climate-associated factors (habitat use, body condition) in explaining the plasma concentrations of contaminants in southern Beaufort Sea (SB) polar bears, and 2) to investigate how climate-associated factors, contaminant concentrations, and pathogen sero-prevalence influence the plasma concentrations of immune-signaling proteins called cytokines. A commercially available multiplex canine cytokine panel was validated for the quantification of five pro- and anti-inflammatory cytokines in polar bear plasma tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), IL-8, IL-10, and interferon gamma-induced protein 10 (IP-10). This panel was then used to measure cytokine concentrations in 49ential adverse consequences on a well-balanced immune system.Every year during the peak winter months (December-January), dense and prolonged fog envelops the Indo-Gangetic Basin (IGB) over the Indian sub-continent leading to economic loss. see more Many efforts are being made to understand its characteristics to improve forecasting skills. see more In the present work Indian National SATellite (INSAT-3D), a geostationary satellite, retrieved fog data available at every 30 min interval throughout the day and night is used to study its evolution, spatial and temporal variability for the winter months of December 2016 and January 2017 in conjunction with surface measurements. Fog data when compared with ground-based horizontal visibility over different stations in IGB showed good relationship, also depicted similar temporal variability in tune with the favorable meteorological parameters of temperature, relative humidity, and wind speed. It is observed that INSAT-3D captured fog very well for visibility ranging from 0 to 500 m representing very dense, dense, and moderate fog, while, the shallow fog with visibility >600 m is captured occasionally. From the maps of spatial and temporal variability of fog, the regions most affected are identified based on fog duration. The intense fog events covering the entire IGB for long duration are observed mostly in the midnight (0000-0400) and early morning (0400-0800) hours (local time) of December as compared to January. While in January, moderate intense fog spans the entire IGB during day time also. Due to increase in pollution levels, including biomass burning as inferred from MODIS fire counts, and stable atmosphere, high aerosol optical depths (AOD) are observed across IGB. The high AOD regions (> 0.8) covering central and west IGB, are also the hotspot regions of fog/smog onset and slowly expand over a larger area and intensify.Naturally complete mixing (i.e., ΔT less then 1 °C across the entire water column) driven by convection in winter is an ideal state for maintaining good water quality, as it spontaneously redistributes dissolved oxygen (DO) over the entire water column and prevents hypolimnetic anoxia and associated pollution. A complete mixing duration is quite short under natural mixing conditions, whereas artificial destratification systems can artificially induce an earlier occurrence of complete mixing, thereby prolonging the span of the naturally complete mixing period by several months. Based on multi-year in situ water quality measurements and meteorological data during natural and artificial mixing periods, this study evaluates the effects of water-lifting aerators (WLAs) and climatic factors on convective mixing processes and their duration. WLA-supplied turbulent kinetic energy (TKE) and WLA-induced hypolimnion warming significantly decrease the water stability and extend the naturally complete mixing period for 2.6-fold. The results indicate that an optimal WLA implementation should immediately achieve complete mixing when surface mixing occurs in autumn. By evaluating the influence of WLAs and other factors on convective mixing, this study provides insights for successful destratification system operations (i.e., WLAs) to replenish oxygen concentrations across the water column and minimize operating costs by taking advantage of climatic conditions. Although our study focuses on WLA-induced mixing, these observations can be applicable to other destratification systems in most of the stratified reservoirs and lakes.Delhi is one of the most polluted cities worldwide and a comprehensive understanding and deeper insight into the air pollution and its sources is of high importance. We report 5 months of highly time-resolved measurements of non-refractory PM2.5 and black carbon (BC). Additionally, source apportionment based on positive matrix factorization (PMF) of the organic aerosol (OA) fraction is presented. The highest pollution levels are observed during winter in December/January. During that time, also uniquely high chloride concentrations are measured, which are sometimes even the most dominant NR-species in the morning hours. With increasing temperature, the total PM2.5 concentration decreases steadily, whereas the chloride concentrations decrease sharply. The concentrations measured in May are roughly 6 times lower than in December/January. PMF analysis resolves two primary factors, namely hydrocarbon-like (traffic-related) OA (HOA) and solid fuel combustion OA (SFC-OA), and one or two secondary factors depending on the season.