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991.
The assessment of the particulate matter (PM) levels and its constituents presented in the atmosphere is an important requirement of the air quality management and air pollution abatement. The heavy metal levels in PM10 are commonly evaluated by experimental measurements; nevertheless, the EC Directives also allow the Regional Governments to estimate the regulated metal levels (Pb in Directive 2008/50/EC and As, Ni and Cd in Directive 2004/107/EC) by objective estimation and modelling techniques. These techniques are proper alternatives to the experimental determination because the required analysis and/or the number of required sampling sites are reduced. The present work aims to estimate the annual levels of regulated heavy metals by means of multivariate linear regression (MLR) and principal component regression (PCR) at four sites in the Cantabria region (Northern Spain). Since the objective estimation techniques may only be applied when the regulated metal concentrations are below to the lower assessment threshold, a previous evaluation of the determined annual levels of heavy metals is conducted to test the fulfilment of the EC Directives requirements. At the four studied sites, the results show that the objective estimations are allowed alternatives to the experimental determination. The annual average metal concentrations are well estimated by the MLR technique in all the studied sites; furthermore, the EC quality requirements for the objective estimations are fulfilled by the developed statistical MLR models. Hence these estimations may be used by Regional Governments as a proper alternative to the experimental measurements for the regulated metal levels assessment. 相似文献
992.
Moyo S Mujuru M McCrindle RI Mokgalaka-Matlala N 《Journal of environmental monitoring : JEM》2011,13(5):1488-1494
Samples of coal were collected from different seams at a South African coal mine and comparative leaching experiments were carried out under various pH conditions and times to investigate the leaching behavior and potential environmental impact of possibly hazardous elements such as As, Cd, Co, Cr, Mn, Ni, Pb, Th and U. The calculated leaching intensities, sequential extraction results and cumulative percentages demonstrate that the leaching behavior of the elements is strongly influenced by the pH, the leaching time and the properties and occurrences of the elements. The leached concentrations of As, Cd, Co, Cr, Mn, Ni and Pb exceeded the maximum concentrations recommended by the Environmental Protection Agency (EPA) for surface water. 相似文献
993.
Ahmed A. Nassr Kamran Hessami Elena D’Alberti Antonella Giancotti Nazlisadat Meshinchiasl Mark I. Evans Daniele Di Mascio Alireza A. Shamshirsaz 《黑龙江环境通报》2023,43(11):1425-1432
To evaluate obstetrical outcomes for women having late amniocentesis (on or after 24 weeks). Electronic databases were searched from inception to January 1st, 2023. The obstetrical outcomes evaluated were gestational age at delivery, preterm birth (PTB) < 37 weeks, PTB within 1 week from amniocentesis, premature prelabor rupture of membranes (pPROM), chorionamnionitis, placental abruption, intrauterine fetal demise (IUFD) and termination of pregnancy (TOP). The incidence of PTB <37 weeks was 4.85% (95% CI 3.48–6.56), while the incidence of PTB within 1 week was 1.42% (95% CI 0.66–2.45). The rate of pPROM was 2.85% (95% CI 1.21–3.32). The incidence of placental abruption was 0.91% (95% CI 0.16–2.25), while the rate of IUFD was 3.66% (95% CI 0.00–14.04). The rate of women who underwent TOP was 6.37% (95%CI 1.05–15.72). When comparing amniocentesis performed before or after 32 weeks, the incidence of PTB within 1 week was 1.48% (95% CI 0.42–3.19) and 2.38% (95% CI 0.40–5.95). Amniocentesis performed late after 24 weeks of gestation is an acceptable option for patients needing prenatal diagnosis in later gestation. 相似文献
994.
Sang-Won Park Sung-Kuk Kim Jeong-Bae Kim Sung-Woo Choi Hilary I. Inyang Shuzo Tokunaga 《Water, Air, & Soil Pollution: Focus》2006,6(1-2):97-110
Halogenated aliphatic compounds (HACs) can be reduced by iron sulfides in aqueous systems. Generally, the thermodynamics and
kinetics of dehalogenation reactions are controlled by the mineralogical and particle surface characteristics of the iron
sulfide, the composition of the HAC and reaction conditions such as component concentrations, pH and Eh. In this theoretical
and experimental investigation of CCl4 and C2Cl6 reduction by FeS and FeS2, the roles of hydrophobic and hydrophilic sites on the iron sulfides were analyzed. Experimental data obtained through zeta
potential measurements, were used along with the Gouy-Chapman model and the simple two-layer surface complexation model to
relate iron sulfide surface hydroxyl densities to the degree of HAC dehalogenation. The surface hydroxyl site densities of
FeS and FeS2 were found to be 0.11 sites/nm2 and 0.21 sites/nm2, respectively. During the dehalogenation reaction process, CCl4 was found to decrease to its first intermediate product CHCl3 within the first 20 hours followed by a slower process of conversion to CH2Cl2. The results also show that FeS is less hydrated (more hydrophobic) than FeS2. For CCl4 and C2Cl6, FeS is a better dehalogenator than FeS2. These results imply that particle surface hydrophobicity is a critical factor in surface-mediated dehalogenation of chlorinated
compounds. 相似文献
995.
Furtak-Cole E. Gillies J. A. Hilgendorf Z. Walker I. J. Nikolich G. 《Environmental Fluid Mechanics》2022,22(6):1399-1420
Environmental Fluid Mechanics - Wind-driven shear stresses drive saltation and dust emissions over sand dunes. However, the complex topography of coastal dunes and practical difficulties in... 相似文献
996.
Volova Tatiana G. Kurachenko Natalya L. Bopp Valentina L. Thomas Sabu Demidenko Aleksey V. Kiselev Evgeniy G. Baranovsky Sergey V. Sukovatyi Aleksey G. Zhila Natalia O. Shishatskaya Ekaterina I. 《Environmental science and pollution research international》2022,29(14):20249-20264
Environmental Science and Pollution Research - The efficacy of slow-release formulations of tribenuron-methyl (TBM) embedded in the matrix of degradable poly(3-hydroxybutyrate) blended with birch... 相似文献
997.
When parasitic infections are severe or highly prevalent among prey, a significant component of the predator's diet may consist of parasitized hosts. However, despite the ubiquity of parasites in most food webs, comparisons of the nutritional quality of prey as a function of infection status are largely absent. We measured the nutritional consequences of chytridiomycete infections in Daphnia, which achieve high prevalence in lake ecosystems (>80%), and tested the hypothesis that Daphnia pulicaria infected with Polycaryum laeve are diminished in food quality relative to uninfected hosts. Compared with uninfected adults, infected individuals were smaller, contained less nitrogen and phosphorus, and were lower in several important fatty acids. Infected zooplankton had significantly shorter carapace lengths (8%) and lower mass (8-20%) than uninfected individuals. Parasitized animals contained significantly less phosphorus (16-18% less by dry mass) and nitrogen (4-6% less) than did healthy individuals. Infected individuals also contained 26-34% less saturated fatty acid and 31-42% less docosahexaenoic acid, an essential fatty acid that is typically low in cladocera, but critical to fish growth. Our results suggest that naturally occurring levels of chytrid infections in D. pulicaria populations reduce the quality of food available to secondary consumers, including planktivorous fishes, with potentially important effects for lake food webs. 相似文献
998.
M. Schratzberger T. A. D. Maxwell K. Warr J. R. Ellis S. I. Rogers 《Marine Biology》2008,153(4):621-642
Spatial variation of populations and their assemblages is an important component of many aspects of ecology, including the
maintenance of species diversity. In nature, organisms are generally aggregated in patches or form gradients or other spatially
related patterns. This investigation quantified the degree of spatial structure in benthic invertebrate assemblages. It examined
the distribution of infaunal assemblages of different size, mobility and contrasting life-history strategies (i.e. meiofaunal
nematodes and macrofaunal polychaetes) in two offshore muddy habitats in the Celtic Deep and the NW Irish Sea off the west
coast of the United Kingdom. The more heterogeneous habitat in the NW Irish Sea was characterised by higher tidal stress and
bottom temperature while greater water depth, mean particle diameter and organic carbon content was typical for the comparatively
homogeneous environment in the Celtic Deep. In both habitats, the environmental conditions became increasingly dissimilar
with separation. A total of 125 nematode and 88 polychaete species were recorded with 69% of the nematode and 49% of polychaete
species present at both study sites. Occurrence frequency of species, species diversity and average similarity of assemblage
composition was higher in the Celtic Deep than in the NW Irish Sea. Results from correlation analyses revealed statistically
robust relationships of community similarity and sample distance. Given their small size and low mobility, nematodes were
more susceptible to within-habitat physical variability than larger-sized, more mobile polychaetes. This, coupled with limits
to long-distance dispersal and likely restrictions in gene flow, resulted in a significant decrease in community similarity
with distance at the spatial scales sampled (i.e. within 0.1–23 km). Polychaetes, in contrast, combined a higher dispersal
potential (>23 km) with a relatively high tolerance to within-habitat environmental variability and these were the most likely
causes for non-significant relationships between the similarity of their assemblages and sample distance. The potential mechanisms
causing the observed variation and implications of results for environmental management strategies are discussed.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
999.
1000.