SciCombinator

Discover the most talked about and latest scientific content & concepts.

Journal: The Science of the total environment

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Airborne biological particles containing viruses, bacteria, and/or fungi can be toxic and cause infections and allergy symptoms. Recently, natural materials such as tea tree oil and Sophora flavescens have shown promising antimicrobial activity when applied as air filter media. Although many of these studies demonstrated excellent antimicrobial efficacy, only a few of them considered external environmental effects such as the surrounding humidity, temperature, and natural degradation of chemicals, all of which can affect the antimicrobial performance of these natural materials. In this study, we investigated the antimicrobial durability of air filters containing airborne nanoparticles from S. flavescens for 5months. Antimicrobial tests and quantitative chemical analyses were performed every 30days. Morphological changes in the nanoparticles were also evaluated by scanning electron microscopy. The major antimicrobial compounds remained stable and active for ~90days at room temperature. After about 90days, the quantities of major antimicrobial compounds decreased noticeably with a consequent decrease in antimicrobial activity. These results are promising for the implementation of new technologies using natural antimicrobial products and provide useful information regarding the average life expectancy of antimicrobial filters using nanoparticles of S. flavescens.

Concepts: Chemistry, Scanning electron microscope, Air filter, Chemical substance, Filters, Antimicrobial, Life expectancy, Tea tree oil

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Medium pressure UV is used for controlling the concentration of combined chlorine (chloramines) in many public swimming pools. Little is known about the fate of other disinfection by-products (DBPs) in UV treatment. Photolysis by medium pressure UV treatment was investigated for 12 DBPs reported to be found in swimming pool water: chloroform, bromodichloromethane, dibromochloromethane, bromoform, dichloroacetonitrile, bromochloroacetonitrile, dibromoacetronitrile, trichloroacetonitrile, trichloronitromethane, dichloropropanone, trichloropropanone, and chloral hydrate. First order photolysis constants ranged 26-fold from 0.020min(-1) for chloroform to 0.523min(-1) for trichloronitromethane. The rate constants generally increased with bromine substitution. Using the UV removal of combined chlorine as an actinometer, the rate constants were recalculated to actual treatment doses of UV applied in a swimming pool. In an investigated public pool the UV dose was equivalent to an applied electrical energy of 1.34kWhm(-3)d(-1) and the UV dose required to removed 90% of trichloronitromethane was 0.4kWhm(-3)d(-1), while 2.6kWhm(-3)d(-1) was required for chloral hydrate and the bromine containing haloacetonitriles and trihalomethanes ranged from 0.6 to 3.1kWhm(-3)d(-1). It was predicted thus that a beneficial side-effect of applying UV for removing combined chlorine from the pool water could be a significant removal of trichloronitromethane, chloral hydrate and the bromine containing haloacetonitriles and trihalomethanes.

Concepts: Chlorination, Pool, Chloroform, Trihalomethane, Swimming pool, Chlorine

28

Dune slacks are a seasonal coastal wetland habitat, whose plant assemblages and soil properties are strongly linked to a fluctuating water table. Climate change is predicted to cause major shifts in sand dune hydrological regimes, yet we know remarkably little about the tolerance of these communities to change, and their precise hydrological requirements are poorly quantified. Dune slack vegetation and soils were sampled within five vegetation types across four west coast UK sites. Relationships between vegetation assemblages, and parameters of soil development (moisture, loss on ignition, pH, KCl extractable ions) and groundwater hydrological regime (annual maximum and minimum water levels and range, duration of flooding) were established to define the environmental tolerances of different communities. In multivariate analysis of the vegetation, the dominant gradient was hydrological: dry to wet, followed by a secondary soil development gradient: young calcareous organic-poor soils to acidic/neutral soils with greater organic matter contents. Most measured hydrological and soil variables explained a significant proportion of observed variation in species composition when tested individually, with the exception of soil nitrate and soil calcium concentrations. Maximum water level was the key hydrological variable, and soil moisture and soil pH were the key soil variables. All hydrological and soil parameters together explained 22.5% of the total species variation. There were significant differences in hydrological and soil parameters between community types, with only 40cm difference in mean annual minimum water levels (averaged over 4years) separating the wettest and the driest dune slack communities. Therefore, predicted declines in water level exceeding 100cm by 2080 are likely to have a major impact on the vegetation of these priority conservation habitats.

Concepts: Level, Surface runoff, Aquifer, Maxima and minima, Potassium, Sand, Hydrology, Soil

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This review critically evaluates the available mercury (Hg) data in Arctic marine biota and the Inuit population against toxicity threshold values. In particular marine top predators exhibit concentrations of mercury in their tissues and organs that are believed to exceed thresholds for biological effects. Species whose concentrations exceed threshold values include the polar bears (Ursus maritimus), beluga whale (Delphinapterus leucas), pilot whale (Globicephala melas), hooded seal (Cystophora cristata), a few seabird species, and landlocked Arctic char (Salvelinus alpinus). Toothed whales appear to be one of the most vulnerable groups, with high concentrations of mercury recorded in brain tissue with associated signs of neurochemical effects. Evidence of increasing concentrations in mercury in some biota in Arctic Canada and Greenland is therefore a concern with respect to ecosystem health.

Concepts: Arctic, Pilot whale, Bear, Megafauna, Narwhal, Pinniped, Polar bear, Inuit

28

Copper (Cu) containing fungicides have been used for more than one century in Europe on agricultural soils, such as vineyard soils. Total Cu concentrations in such soils can exceed toxicological limits that are commonly derived using artificially spiked soils. This study surveyed Cu toxicity in vineyard soils with reference to soils spiked with CuCl(2). Soil was collected in six established European vineyards. At each site, samples representing a Cu concentration gradient were collected. A control (uncontaminated) soil sampled nearby the vineyard was spiked with CuCl(2). Toxicity was tested using standard ecotoxicity tests: two plant assays (Lycopersicon esculentum Miller (tomato) and Hordeum vulgare L. (barley) growth), one microbial assay (nitrification) and one invertebrate assay (Enchytraeus albidus reproduction). Maximal total Cu concentrations in the vineyard sites ranged 435-690mgCukg(-1), well above the local background (23-105mgCukg(-1)). Toxicity in spiked soils (50% inhibition) was observed at added soil Cu concentrations from 190 to 1039mgCukg(-1) (mean 540mgCukg(-1)) depending on the assay and the site. In contrast, significant adverse effects were only found for three bioassays in vineyard samples of one site and for two bioassays in another site. Biological responses in these cases were more importantly explained by other soil properties than soil Cu. Overall, no Cu toxicity to plants, microbial processes and invertebrates was observed in vineyard soil samples at Cu concentrations well above European Union limits protecting the soil ecosystem.

Concepts: Toxicity, Barley, Europe, Archaea, Copper, Soil, Toxicology, Viticulture

28

The Potomac River basin is an area where a high prevalence of abnormalities such as testicular oocytes (TO), skin lesions, and mortality has been observed in smallmouth bass (SMB, Micropterus dolomieu). Previous research documented a variety of chemicals in regional streams, implicating chemical exposure as one plausible explanation for these biological effects. Six stream sites in the Potomac basin (and one out-of-basin reference site) were sampled to provide an assessment of chemicals in these streams. Potential early life-stage exposure to chemicals detected was assessed by collecting samples in and around SMB nesting areas. Target chemicals included those known to be associated with important agricultural and municipal wastewater sources in the Potomac basin. The prevalence and severity of TO in SMB were also measured to determine potential relations between chemistry and biological effects. A total of 39 chemicals were detected at least once in the discrete-water samples, with atrazine, caffeine, deethylatrazine, simazine, and iso-chlorotetracycline being most frequently detected. Of the most frequently detected chemicals, only caffeine was detected in water from the reference site. No biogenic hormones/sterols were detected in the discrete-water samples. In contrast, 100 chemicals (including six biogenic hormones/sterols) were found in a least one passive-water sample, with 25 being detected at all such samples. In addition, 46 chemicals (including seven biogenic hormones/sterols) were found in the bed-sediment samples, with caffeine, cholesterol, indole, para-cresol, and sitosterol detected in all such samples. The number of herbicides detected in discrete-water samples per site had a significant positive relation to TO(rank) (a nonparametric indicator of TO), with significant positive relations between TO(rank) and atrazine concentrations in discrete-water samples and to total hormone/sterol concentration in bed-sediment samples. Such significant correlations do not necessarily imply causation, as these chemical compositions and concentrations likely do not adequately reflect total SMB exposure history, particularly during critical life stages.

Concepts: Sample, Edible fish, Centrarchidae, Black bass, Potomac River, Water, Chemistry, Smallmouth bass

28

Following a wide-area biological terror attack, numerous decontamination technologies, techniques, and strategies will be required for rapid remediation. Establishing an understanding of how disinfectants will perform under field conditions is of critical importance. The purpose of this study was to determine the efficacy of several liquid decontaminants, when used to inactivate vegetative biological agents on environmental surfaces. Aluminum, carpet, concrete, glass, and wood coupons were inoculated with 1×10(8)CFU of Burkholderia mallei, Francisella tularensis, Vibrio cholerae, or Yersinia pestis. Using spray-based application methods, decontamination was then attempted with pH-adjusted bleach, 1% citric acid, 70% ethanol, quaternary ammonia, or Pine-Sol®. Results indicated that decontamination efficacy varied significantly by decontaminant and organism. Materials such as wood are difficult to decontaminate, even when using sporicides. The data presented here will help responders develop efficacious remediation strategies following a large-scale contamination incident.

Concepts: Bacteria, Vinegar, Fungus, Francisella tularensis, Yersinia pestis, Burkholderia mallei, Vibrio cholerae, Acid

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Intensive firecracker/firework displays during Chinese New Year (CNY) release fine particles and gaseous pollutants into the atmosphere, which may lead to serious air pollution. We monitored ambient PM(2.5) and black carbon (BC) concentrations at a regional background site in the Yellow River Delta region during the CNY in 2011. Our monitoring data and MOUDI images showed that there was a haze event during the CNY. Daily average PM(2.5) concentration reached 183μgm(-3) during the CNY, which was six times higher than that before and after the CNY. Similarly, the black carbon (BC) concentrations were elevated during the CNY. In order to confirm whether the firecracker/firework related emission is the main source of the haze particles, we further analyzed the morphology and chemical composition of individual airborne particles collected before, during and after the CNY by using transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy (TEM/EDS). We found that sulfate and organic-rich particles were dominant in the atmosphere before and after the CNY. In contrast, K-rich sulfates and other metal (e.g., Ba-rich, Al-rich, Mg-rich, and Fe-rich) particles were much more abundant than ammoniated sulfate particles during the CNY. These data suggest that it was the aerosol particles from the firecracker/firework emissions that induced the regional haze episode during the CNY. In individual organic and K-rich particles, we often found more than two types of nano-metal particles. These metal-bearing particles also contained abundant S but not Cl. In contrast, fresh metal-bearing particles from firecrackers generated in the laboratory contained abundant Cl with minor amounts of S. This indicates that the firecracker/firework emissions during the CNY significantly changed the atmospheric transformation pathway of SO(2) to sulfate.

Concepts: Sulfate, Electron, Pollution, Air pollution, Fireworks, Chinese New Year, Atmosphere, Particulate

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This research examines traffic-related trace element emissions and their uptake by plants grown in urban roadside environments in Toronto, Canada. Oregano (Origanum vulgare), beets (Beta vulgaris) and eggplants (Solanum melongena) were cultivated at four locations with variable traffic-related metal inputs in 2010. The top 30cm of soil at the medium-traffic location was first replaced with a triple mix soil (topsoil, compost and peat) to control for pre-existing contamination. The same soil was used to cultivate at the two no/low traffic locations. Soil at the heavy traffic location was not remediated. Soil, plant tissue and plant rhizosphere samples were collected for the analysis of a range of traffic-related metal(loids) using ICP-MS, including Cr, Mn, Cu, Ni, Cd, As, Sb and Pb. Samples were digested with HNO(3) and HCl using a microwave-assisted digestion procedure and then treated with HF prior to analysis. Two certified reference materials, San Joaquin soil (NIST 2709a) and trace elements in spinach leaves (NIST 1570a), were used for QA/QC purposes. Metal(loid) concentrations and accumulation over time were highly variable at the medium traffic site where the soil was replaced. Mn (p<0.10), As (p<0.10) and Sb (p<0.01) concentrations significantly increased in bulk soils from May to November 2010, while Ce (p<0.01) and Cd (p<0.10) levels decreased. For instance, median As concentrations increased from 4.39 to 8.40mg/kg over this period. Metals were found to be more bioaccessible to O. vulgare grown in the new soil at the medium traffic volume site, compared to the aged soil at the heavy traffic location. Several elements, most notably Cd, were also found to accumulate in the root zone of sampled S. melongena. Metal concentrations in S. melongena rhizosphere were better predictors of plant tissue levels, providing evidence that soil quality guidelines based on total metal concentrations for bulk soils are inadequate.

Concepts: Marjoram, Fruit, Heavy metal music, Lamiaceae, Origanum, Soil, Oregano, Greek cuisine

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Little is known about the intensity and extension of subsurface urban heat islands (UHI), and the individual role of the driving factors has not been revealed either. In this study, we compare groundwater temperatures in shallow aquifers beneath six German cities of different size (Berlin, Munich, Cologne, Frankfurt, Karlsruhe and Darmstadt). It is revealed that hotspots of up to +20K often exist, which stem from very local heat sources, such as insufficiently insulated power plants, landfills or open geothermal systems. When visualizing the regional conditions in isotherm maps, mostly a concentric picture is found with the highest temperatures in the city centers. This reflects the long-term accumulation of thermal energy over several centuries and the interplay of various factors, particularly in heat loss from basements, elevated ground surface temperatures (GST) and subsurface infrastructure. As a primary indicator to quantify and compare large-scale UHI intensity the 10-90%-quantile range UHII(10-90) of the temperature distribution is introduced. The latter reveals, in comparison to annual atmospheric UHI intensities, an even more pronounced heating of the shallow subsurface.

Concepts: Internal energy, Groundwater, Heat pump, Energy, Urban heat island, Temperature, Thermodynamics, Heat