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Raphael Mainiero Marian Kazda 《Environmental pollution (Barking, Essex : 1987)》2009,157(10):2638-2644
Fine root dynamics (diameter < 1 mm) in mature Fagus sylvatica, with the canopies exposed to ambient or twice-ambient ozone concentrations, were investigated throughout 2004. The focus was on the seasonal timing and extent of fine root dynamics (growth, mortality) in relation to the soil environment (water content, temperature). Under ambient ozone concentrations, a significant relationship was found between fine root turnover and soil environmental changes indicating accelerated fine root turnover under favourable soil conditions. In contrast, under elevated ozone, this relationship vanished as the result of an altered temporal pattern of fine root growth. Fine root survival and turnover rate did not differ significantly between the different ozone regimes, although a delay in current-year fine root shedding was found under the elevated ozone concentrations. The data indicate that increasing tropospheric ozone levels can alter the timing of fine root turnover in mature F. sylvatica but do not affect the turnover rate. 相似文献
45.
Dias Raphael Igor Webster Michael S. Macedo Regina H. 《Behavioral ecology and sociobiology》2017,71(9):1-11
Behavioral Ecology and Sociobiology - Studies with individual rodents have revealed that they display protean (unpredictable) behavior when attacked by an owl. Other studies have revealed that... 相似文献
46.
Long-Term Variability in Bioassessments: A Twenty-Year Study from Two Northern California Streams 总被引:2,自引:2,他引:0
Long-term variability of bioassessments has not been well evaluated. We analyzed a 20-year data set (1984–2003) from four
sites in two northern California streams to examine the variability of bioassessment indices (two multivariate RIVPACS-type
O/E scores and one multimetric index of biotic integrity, IBI), as well as eight metrics. All sites were sampled in spring;
one site was also sampled in summer. Variability among years was high for most metrics (coefficients of variation, CVs ranging
from 16% to 246% in spring) but lower for indices (CVs of 22–26% for the IBI and 21–32% for O/E scores in spring), which resulted
in inconsistent assessments of biological condition. Variance components analysis showed that the time component explained
variability in all metrics and indices, ranging from 5% to 35% of total variance explained. The site component was large (i.e.,
>40%) for some metrics (e.g., EPT richness), but nearly absent from others (e.g., Diptera richness). Seasonal analysis at
one site showed that variability among seasons was small for some metrics or indices (e.g., Coleoptera richness), but large
for others (e.g., EPT richness, O/E scores). Climatic variables did not show consistent trends across all metrics, although
several were related to the El Ni?o Southern Oscillation Index at some sites. Bioassessments should incorporate temporal variability
during index calibration or include climatic variability as predictive variables to improve accuracy and precision. In addition,
these approaches may help managers anticipate alterations in reference streams caused by global climate change and high climatic
variability. 相似文献
47.
Raphael D. Mazor Kenneth Schiff Kerry Ritter Andy Rehn Peter Ode 《Environmental monitoring and assessment》2010,167(1-4):91-104
Biomonitoring programs are often required to assess streams for which assessment tools have not been developed. For example, low-gradient streams (slope ≤1%) comprise 20–30% of stream miles in California and are of particular interest to watershed managers, yet most sampling methods and bioassessment indices in the state were developed in high-gradient systems. This study evaluated the performance of three sampling methods [targeted riffle composite (TRC), reach-wide benthos (RWB), and the margin–center–margin modification of RWB (MCM)] and two indices [the Southern California Index of Biotic Integrity (SCIBI) and the ratio of observed to expected taxa (O/E)] in low-gradient streams in California for application in this habitat type. Performance was evaluated in terms of efficacy (i.e., ability to collect enough individuals for index calculation), comparability (i.e., similarity of assemblages and index scores), sensitivity (i.e., responsiveness to disturbance), and precision (i.e., ability to detect small differences in index scores). The sampling methods varied in the degree to which they targeted macroinvertebrate-rich microhabitats, such as riffles and vegetated margins, which may be naturally scarce in low-gradient streams. The RWB method failed to collect sufficient numbers of individuals (i.e., ≥450) to calculate the SCIBI in 28 of 45 samples and often collected fewer than 100 individuals, suggesting it is inappropriate for low-gradient streams in California; failures for the other methods were less common (TRC, 16 samples; MCM, 11 samples). Within-site precision, measured as the minimum detectable difference (MDD) was poor but similar across methods for the SCIBI (ranging from 19 to 22). However, RWB had the lowest MDD for O/E scores (0.20 versus 0.24 and 0.28 for MCM and TRC, respectively). Mantel correlations showed that assemblages were more similar within sites among methods than within methods among sites, suggesting that the sampling methods were collecting similar assemblages of organisms. Statistically significant disagreements among methods were not detected, although O/E scores were higher for RWB samples than TRC. Index scores suggested impairment at all sites in the study. Although index scores did not respond strongly to several measurements of disturbance in the watershed, percent agriculture showed a significant, negative relationship with O/E scores. 相似文献
48.
Kreangkrai Maneeintr Amr Henni Raphael O. Idem Paitoon Tontiwachwuthikul Andrew G.H. Wee 《Process Safety and Environmental Protection》2008,86(4):291
Densities, viscosities and refractive indices of 4-diethylamino-2-butanol + water mixtures were measured over the entire concentration range of 0–1 mole fraction and temperature range from 298.15 to 343.15 K. Excess molar volumes, viscosity deviations, and molar refraction changes were calculated from the measurement results and correlated as a function of the mole fractions. Various models were used for correlation with the measured data. Out of these, the Redlich–Kister equation was the most suitable model that correlated best with experimental data. The percent absolute deviations obtained with this model were 0.03% for density, 0.88% for viscosity and 0.009% for refractive index. 相似文献
49.
Isenberg G Edinger R Ebner J 《Environmental science and pollution research international》2002,9(2):99-104
Transportation contributes to energy consumption and greenhouse gas emissions, while sustainable mobility requires reductions in both areas. Alternative fuels from natural gas and from renewable resources can contribute in the mid and long-term to the fuel market for mobile as well as stationary applications. The lack of reliable data on emissions, energy chain efficiencies, and costs demonstrates the need for field tests and demonstration projects. Fuel cells offer the technology to use ‘new fuels’ in a highly efficient way. 相似文献
50.
Andreas Stork Raphael Witte Fritz Führ 《Environmental science and pollution research international》1994,1(4):234-245
Volatilization from treated areas is a major source of pesticide residues in air, fog, and rain. This may lead to long-range
transport of pesticide residues to remote areas. Up to now most information on pesticide volatilization has come from laboratory
experiments under controlled conditions. A new system has been designed and developed to measure the volatile losses of14C-labelled chemicals after application; the method compares with agricultural practice of treating soils or plants grown in
lysimeters. Sensitive analytical methods guarantee a distinction between residues of unchanged pesticide, its metabolites
or14CO2 as a mineralization product released into the air. 相似文献