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851.
Lowenthal DH Kumar N Hand J Day D Kreidenweis S Collett J Lee T Ashbaugh L 《Journal of the Air & Waste Management Association (1995)》2003,53(10):1273-1279
The hygroscopic properties of the organic fraction of aerosols are poorly understood. The ability of organic aerosols to absorb water as a function of relative humidity (RH) was examined using data collected during the 1999 Big Bend Regional Aerosol and Visibility Observational Study (BRAVO). (On average, organics accounted for 22% of fine particulate matter with an aerodynamic diameter less than 2.5 microm (PM2.5) mass). Hourly RH exceeded 80% only 3.5% of the time and averaged 44%. BRAVO aerosol chemical composition and dry particle size distributions were used to estimate PM2.5 light scattering (Bsp) at low and high ambient RH. Liquid water growth associated with inorganic species was sufficient to account for measured Bsp for RH between 70 and 95%. 相似文献
852.
Eun Jung Choy Qtae Jo Hyo-Bang Moon Chang-Keun Kang Ju-Chan Kang 《Marine Biology》2007,151(1):157-165
The time-course of uptake and elimination of benzo(a)pyrene (BaP) for the Pacific oyster, Crassostrea gigas and reproduction damage and reproductive outputs were studied. Sexually immature C. gigas broodstock were fed for 28 days with live algae grown in four BaP solutions of 0, 50, 500, and 5,000 μg L−1 (hereafter, control, 50, 500, and 5,000 oysters) and were subsequently conditioned to maturation by a feeding with BaP-free
live algae under temperature manipulation for another 28 days. The 5,000 μg L−1 oysters gained a steady state concentration, around 30,000 ng g−1 d.w. for digestive gland, a week earlier compared to the 500 μg L−1 oysters. The earlier gain or longer persistence of the steady state concentration influenced elimination of BaP, with an
eliminating trend for 500 μg L−1 oysters, while no elimination for 5,000 μg L−1 oysters. The maternal persistence of the steady state concentration resulted in significant damages in the reproductive success
and their reproductive outputs in terms of the hatching rate and larval growth, survival, and settlement. The 50 μg L−1 oysters remained far below the steady state concentration, and showed a manifest eliminating behavior during the subsequent
BaP-free 28 day maturation period. The reproductive success and initial larval events of 50 μg L−1 oysters were comparable to those of control. However, the damage potential of the 50 μg L−1 oysters might be more significant if their maternal exposure continued beyond 28 days, since the accumulation profile at this
dose was linear. 相似文献
853.
Alex Kacelnik Marco Vasconcelos Tiago Monteiro Justine Aw 《Behavioral ecology and sociobiology》2011,65(3):547-558
Charles Darwin aided his private decision making by an explicit deliberation, famously deciding whether or not to marry by
creating a list of points in a table with two columns: “Marry” and “Not Marry”. One hundred seventy-two years after Darwin’s
wedding, we reconsider whether this process of choice, under which individuals assign values to their options and compare
their relative merits at the time of choosing (the tug-of-war model), applies to our experimental animal, the European Starling,
Sturnus vulgaris. We contrast this with the sequential choice model that postulates that decision-makers make no comparison between options
at the time of choice. According to the latter, behaviour in simultaneous choices reflects adaptations to contexts with sequential
encounters, in which the choice is whether to take an opportunity or let it pass. We postulate that, in sequential encounters,
the decision-maker assigns (by learning) a subjective value to each option, reflecting its payoff relative to background opportunities.
This value is expressed as latency and/or probability to accept each opportunity as opposed to keep searching. In simultaneous
encounters, choice occurs through each option being processed independently, by a race between the mechanisms that generate
option-specific latencies. We describe these alternative models and review data supporting the predictions of the sequential
choice model. 相似文献
854.
Larisa Lee Cruz Rona A. R. McGill Simon J. Goodman Keith C. Hamer 《Marine Biology》2012,159(4):873-880
Stable isotope analysis of carbon and nitrogen is frequently used to study the diets and foraging ecology of marine predators.
However, isotopic values may also be affected by an individual’s nutritional status and associated physiological processes.
Here, we use C and N stable isotopes in blood and feathers of blue-footed booby chicks at the Galápagos Islands to examine
how isotopic values are related to body condition and growth rate, and to assess the consistency in the isotope ratios of
individuals during growth. Size dimorphism in blue-footed boobies provided an additional opportunity to examine how isotope
ratios differ between sexes in relation to body size and growth rate. There was no significant difference between sexes but
both C and N stable isotopes were significantly negatively related to the body condition of chicks. These data were consistent
with individual variation in physiological processes affecting fractionation, although we cannot rule out the possibility
that they were also influenced to some extent by population-level variation in the stable isotope ratios of prey fed to chicks,
for instance related to prey size, depth or lipid content. Our results highlight the need for methods that take proper account
of confounding physiological factors in isotopic studies of foraging ecology and diet. 相似文献
855.
Ranjan Kumar Mohapatra Pankaj Kumar Parhi Hrudayanath Thatoi 《Chemistry and Ecology》2017,33(2):114-130
Hexavalent chromium-tolerant (1500?mg/L) bacterium MW1 was isolated from harbour water of Paradip Port and evaluated for Cr(VI) reduction potential. The isolate was identified as Exiguobacterium indicum by biochemical and 16S rRNA gene sequence methods. Salt tolerance of the bacterium was evaluated in a wide range of NaCl concentrations (0.5–13%, w/v). The Cr(VI) reduction of the strain was evaluated and optimised with varied Cr(VI) concentrations (100–1000?mg/L), pH (5.0–9.0), temperature (30–40°C) and shaking velocity (100–150?rpm) in two different minimal media (M9 and Acetate). Under optimised conditions, after 192?h of incubation nearly 92%, 50% and 46% reduction in the M9 minimal medium and 91%, 47% and 40% reduction in the acetate minimal medium were observed for 100, 500 and 1000?mg/L of Cr(VI), respectively. The exponential rate equation for Cr(VI) reduction yielded higher rate constant value, that is, 1.27?×?10?2?h?1 (M9) and 1.17?×?10?2?h?1 (Acetate) in case of 100?mg/L and became lower for 500 and 1000?mg/L Cr(VI) concentrations. Further, the association of bacterial cells with reduced product was ascertained by Fourier transform infrared spectrometer, UV–Vis–DRS and field-emission scanning electron microscope–energy-dispersive X-ray analyses. The above study suggests that the higher reducing ability of the marine bacterium E. indicum MW1 will be suitable for Cr(VI) reduction from saline effluents. 相似文献
856.
Ranjan RK Ramanathan A Singh G Chidambaram S 《Environmental monitoring and assessment》2008,147(1-3):389-411
The 26 December 2004-Tsunami has deposited sediments in the Pichavaram mangrove ecosystem, east coast of India. Ten surface and three core sediment samples were collected within thirty days of the event. High concentrations of Cd, Cu, Cr, Pb, and Ni were observed in the tsunamigenic sediments. With respect to Fe, Zn, and Mn, there was little variation as compared to pre-tsunami values. The geo-accumulation index was calculated in order to assess the contamination of heavy metals in the sediments. The sediments were extremely contaminated with respect to Cd and they showed moderate to strong contamination with respect to Cr, Pb and Ni. The study highlighted the future risk of enhanced metal pollution in near future in this mangrove ecosystem. 相似文献
857.
Assessing land use impacts on flood processes in complex terrain by using GIS and modeling approach 总被引:1,自引:0,他引:1
Y. B. Liu F. De Smedt L. Hoffmann L. Pfister 《Environmental Modeling and Assessment》2005,9(4):227-235
A distributed hydrologic modeling and GIS approach is applied for the assessment of land use impact in the Steinsel sub-basin, Alzette, Grand-Duchy of Luxembourg. The assessment focuses on the runoff contributions from different land use classes and the potential impact of land use changes on runoff generation. The results show that the direct runoff from urban areas is dominant for a flood event compared with runoff from other land use areas in this catchment, and tends to increase for small floods and for the dry season floods, whereas the interflow from forested, pasture and agricultural field areas contributes to the recession flow. Significant variations in flood volume, peak discharge, time to the peak, etc., are found from the model simulation based on the three hypothetical land use change scenarios. 相似文献
858.
Carolina Oliveira de Santana Taíse Bomfim de Jesus William Moura de Aguiar Washington de Jesus Sant’anna Franca-Rocha Carlos Alberto Caroso Soares 《Environmental monitoring and assessment》2017,189(3):123
In this study, an analysis was performed on the concentrations of the trace elements Al, As, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V, and Zn in muscle of two carnivorous and one planktivorous fish species collected at Todos os Santos Bay (BTS). The accumulation order of the trace elements in Lutjanus analis was Al >Zn >Fe >Cr >Ba >Ni. In Cetengraulis edentulus, the order was Al >Fe >Zn >Cr >Ni >Mn >As. In the species Diapterus rhombeus, the order was Al >Fe >Zn >Cr >Ni >Mn >Cd. To determine the risk related to the consumption of fish, toxicity guidelines were used as standard references. It was observed that the species C. edentulus contained concentrations of As exceeding WHO limits, but these concentrations were acceptable according to the Agência Nacional de Vigilância Sanitária (ANVISA) guidelines. Cd levels were found only in D. rhombeus and in low concentrations according to the determinations of WHO and ANVISA. Pb levels were not detected in any of the three fish species. The analyzed elements did not differ statistically according to the species and feeding habits. The results point to possible risks of human contamination by As related to the consumption of the fish species C. edentulus from the BTS. 相似文献
859.
Rapid urban development has led to a critical negative impact on water bodies flowing in and around urban areas. In the present study, 25 physiochemical and biological parameters have been studied on water samples collected from the entire section of a small river originating and ending within an urban area. This study envisaged to assess the water quality status of river body and explore probable sources of pollution in the river. Weighted arithmetic water quality index (WQI) was employed to evaluate the water quality status of the river. Multivariate statistical techniques namely cluster analysis (CA) and principal component analysis (PCA) were applied to differentiate the sources of variation in water quality and to determine the cause of pollution in the river. WQI values indicated high pollution levels in the studied water body, rendering it unsuitable for any practical purpose. Cluster analysis results showed that the river samples can be divided into four groups. Use of PCA identified four important factors describing the types of pollution in the river, namely (1) mineral and nutrient pollution, (2) heavy metal pollution, (3) organic pollution, and (4) fecal contamination. The deteriorating water quality of the river was demonstrated to originate from wide sources of anthropogenic activities, especially municipal sewage discharge from unplanned housing areas, wastewater discharge from small industrial units, livestock activities, and indiscriminate dumping of solid wastes in the river. Thus, the present study effectively demonstrates the use of WQI and multivariate statistical techniques for gaining simpler and meaningful information about the water quality of a lotic water body as well as to identify of the pollution sources. 相似文献
860.
Nabil El Moçayd Sophie Ricci Nicole Goutal Mélanie C. Rochoux Sébastien Boyaval Cédric Goeury Didier Lucor Olivier Thual 《Environmental Modeling and Assessment》2018,23(3):309-331
Assessing epistemic uncertainties is considered as a milestone for improving numerical predictions of a dynamical system. In hydrodynamics, uncertainties in input parameters translate into uncertainties in simulated water levels through the shallow water equations. We investigate the ability of generalized polynomial chaos (gPC) surrogate to evaluate the probabilistic features of water level simulated by a 1-D hydraulic model (MASCARET) with the same accuracy as a classical Monte Carlo method but at a reduced computational cost. This study highlights that the water level probability density function and covariance matrix are better estimated with the polynomial surrogate model than with a Monte Carlo approach on the forward model given a limited budget of MASCARET evaluations. The gPC-surrogate performance is first assessed on an idealized channel with uniform geometry and then applied on the more realistic case of the Garonne River (France) for which a global sensitivity analysis using sparse least-angle regression was performed to reduce the size of the stochastic problem. For both cases, Galerkin projection approximation coupled to Gaussian quadrature that involves a limited number of forward model evaluations is compared with least-square regression for computing the coefficients when the surrogate is parameterized with respect to the local friction coefficient and the upstream discharge. The results showed that a gPC-surrogate with total polynomial degree equal to 6 requiring 49 forward model evaluations is sufficient to represent the water level distribution (in the sense of the \(\ell _2\) norm), the probability density function and the water level covariance matrix for further use in the framework of data assimilation. In locations where the flow dynamics is more complex due to bathymetry, a higher polynomial degree is needed to retrieve the water level distribution. The use of a surrogate is thus a promising strategy for uncertainty quantification studies in open-channel flows and should be extended to unsteady flows. It also paves the way toward cost-effective ensemble-based data assimilation for flood forecasting and water resource management. 相似文献