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71.
Evelyne Brisebois Marc Veillette Vanessa Dion-Dupont Jacques Lavoie Jacques Corbeil Alexander Culley Caroline Duchaine 《环境科学学报(英文版)》2018,30(5):45-53
Wastewater treatment center(WTC) workers may be vulnerable to diseases caused by viruses, such as the common cold, influenza and gastro-intestinal infections. Although there is a substantial body of literature characterizing the microbial community found in wastewater, only a few studies have characterized the viral component of WTC aerosols,despite the fact that most diseases affecting WTC workers are of viral origin and that some of these viruses are transmitted through the air. In this study, we evaluated in four WTCs the presence of 11 viral pathogens of particular concern in this milieu and used a metagenomic approach to characterize the total viral community in the air of one of those WTCs. The presence of viruses in aerosols in different locations of individual WTCs was evaluated and the results obtained with four commonly used air samplers were compared.We detected four of the eleven viruses tested, including human adenovirus(h Ad V),rotavirus, hepatitis A virus(HAV) and Herpes Simplex virus type 1(HSV1). The results of the metagenomic assay uncovered very few viral RNA sequences in WTC aerosols, however sequences from human DNA viruses were in much greater relative abundance. 相似文献
72.
Marc Naguib 《Behavioral ecology and sociobiology》1997,40(6):385-393
Male territorial song birds are usually spaced far apart and most often hear conspecific song after it has been degraded
by propagation through the environment. Their ability to use the degradation of songs to assess the distance of a singing
rival without approaching (called ranging) presumably increases the efficiency of defending a territory. In order to assess
degradation in a song the receiver needs to compare the characteristics of the received song to its characteristics at the
source or at different distances. Earlier experiments on ranging in species with song repertoires have suggested that prior
familiarity with the particular song type is necessary for ranging. Here I show that male Carolina wrens (Thryothorus ludovicianus) can use either temporal or spectral characteristics for ranging song types which they were unlikely to have heard previously.
Playbacks consisting of only one song prevented subjects' close-range experience with the loudspeaker, and flights beyond
the loudspeaker provided direct evidence for over-assessment of distance when songs were degraded. Because ranging of songs
was not affected by the degree of familiarity with the song type, this experiment provides no evidence that song repertoires
hinder ranging in Carolina wrens, as suggested by Morton's ranging hypothesis. Instead, at least approximate ranging of songs
is evidently possible by assessment of degradation in general features of a species' songs.
Received: 9 August 1996 / Accepted after revision: 15 February 1997 相似文献
73.
Schichtel BA Gebhart KA Malm WC Barna MG Pitchford ML Knipping EM Tombach IH 《Journal of the Air & Waste Management Association (1995)》2005,55(11):1709-1725
The Big Bend Regional Aerosol and Visibility Observational (BRAVO) study was an intensive monitoring study from July through October 1999 followed by extensive assessments to determine the causes and sources of haze in Big Bend National Park, located in Southwestern Texas. Particulate sulfate compounds are the largest contributor of haze at Big Bend, and chemical transport models (CTMs) and receptor models were used to apportion the sulfate concentrations at Big Bend to North American source regions and the Carbón power plants, located 225 km southeast of Big Bend in Mexico. Initial source attribution methods had contributions that varied by a factor of > or =2. The evaluation and comparison of methods identified opposing biases between the CTMs and receptor models, indicating that the ensemble of results bounds the true source attribution results. The reconciliation of these differences led to the development of a hybrid receptor model merging the CTM results and air quality data, which allowed a nearly daily source apportionment of the sulfate at Big Bend during the BRAVO study. The best estimates from the reconciliation process resulted in sulfur dioxide (SO2) emissions from U.S. and Mexican sources contributing approximately 55% and 38%, respectively, of sulfate at Big Bend. The distribution among U.S. source regions was Texas, 16%; the Eastern United States, 30%; and the Western United States, 9%. The Carbón facilities contributed 19%, making them the largest single contributing facility. Sources in Mexico contributed to the sulfate at Big Bend on most days, whereas contributions from Texas and Eastern U.S. sources were episodic, with their largest contributions during Big Bend sulfate episodes. On the 20% of the days with the highest sulfate concentrations, U.S. and Mexican sources contributed approximately 71% and 26% of the sulfate, respectively. However, on the 20% of days with the lowest sulfate concentrations, Mexico contributed 48% compared with 40% for the United States. 相似文献
74.
Metal accumulation in intertidal litter through decomposing leaf blades, sheaths and stems of Phragmites australis 总被引:3,自引:0,他引:3
Metal contents of decomposing leaf blades, leaf sheaths and stems of common reed (Phragmites australis) were monitored by a litter bag method on the sediment of an intertidal brackish marsh in the Scheldt estuary (The Netherlands). On monthly intervals, two litter bags were retrieved from the marsh during 9 months for both leaf blades and sheaths and during 16 months for stems. All samples were dried, weighed and analysed for ash and Cd, Cu, Cr, Ni, Pb and Zn contents. Most concentrations increased considerably during the decomposition. Generally, also a very important net metal inflow into the litter bags could be observed. The inflow was highest for leaf blades. High correlations between ash contents and metal concentrations for leaf blades suggest that the increase of leaf blade metal contents can be due to physicochemical sorption of dissolved metals and an important infiltration of mud particles, which were not removed by rinsing the leaf blades with distilled water preceding the analyses. For stems, smaller amounts of inflowing ash and even outflowing ash amounts were found, which suggests that inflow of inorganic particles is not the major factor determining metal accumulation by stems on medium term. Ergosterol concentrations in stem tissue however proved to be correlated with metal contents, which suggests a significant role of fungal litter colonizers in metal accumulation. For leaf sheaths, the effects of physicochemical sorption, infiltration of mud particles and incorporation by microbial litter colonizers do not seem to be as pronounced as for stems and leaf blades. 相似文献
75.
Hairy root cultures of Daucus carota L., Ipomoea batatas L. and Solanum aviculare Forst were investigated for their susceptibility to the highly toxic pollutants phenol and chlorophenols and for the involvement of inherent peroxidases in the removal of phenols from liquid media. Roots of D. carota grew normally in medium containing 1000 micromol l(-1) of phenol, whilst normal growth of roots of I. batatas and S. aviculare was only possible at levels up to 500 micromol l(-1). In the presence of chlorophenols, normal root growth was possible only in concentrations not exceeding 50 micromol l(-1), except for I. batatas which was severely affected at all concentrations. Despite the reduction in biomass, the growth of S. aviculare cultures was sustained in medium containing up to 2000 micromol l(-1) of phenol or 2-chlorophenol, and up to 500 micromol l(-1) of 2,6-dichlorophenol. The amounts of phenol removed by the roots within 72 h of treatment were 72.7%, 90.7% and 98.6% of the initial concentration for D. carota, I. batatas and S. aviculare, respectively. For the removal of 2,6-dichlorophenol the values were, respectively, 83.0%, 57.7% and 73.1%. Phenols labelled with 14C were absorbed by the root tissues and condensed with highly polar cellular substances as well as being incorporated into the cell walls or membranes. The results suggest that S. aviculare, an ornamental plant, would be best suited for remediation trials under field conditions. 相似文献
76.
Perrodin Y Babut M Bedell JP Bray M Clement B Delolme C Devaux A Durrieu C Garric J Montuelle B 《Environment international》2006,32(6):804-814
The implementation of an ecological risk assessment framework is presented for dredged material deposits on soil close to a canal and groundwater, and tested with sediment samples from canals in northern France. This framework includes two steps: a simplified risk assessment based on contaminant concentrations and a detailed risk assessment based on toxicity bioassays and column leaching tests. The tested framework includes three related assumptions: (a) effects on plants (Lolium perenne L.), (b) effects on aquatic organisms (Escherichia coli, Pseudokirchneriella subcapitata, Ceriodaphnia dubia, and Xenopus laevis) and (c) effects on groundwater contamination. Several exposure conditions were tested using standardised bioassays. According to the specific dredged material tested, the three assumptions were more or less discriminatory, soil and groundwater pollution being the most sensitive. Several aspects of the assessment procedure must now be improved, in particular assessment endpoint design for risks to ecosystems (e.g., integration of pollutant bioaccumulation), bioassay protocols and column leaching test design. 相似文献
77.
Mitochondrial DNA Variability of the Gray Wolf: Genetic Consequences of Population Decline and Habitat Fragmentation 总被引:3,自引:0,他引:3
Robert K. Wayne Niles Lehman Marc W. Allard Rodney L. Honeycutt 《Conservation biology》1992,6(4):559-569
The gray wolf is a large, highly mobile predator whose original geographic range included most of the Northern Hemisphere. High rates of genetic exchange probably characterized even distantly-separated populations in the past, but recent population declines and habitat fragmentation have isolated previously contiguous populations, especially in the Old World. We examine mitochondrial DNA (mtDNA) variability among twenty-six populations of wolves from throughout their geographic range. We find eighteen mtDNA genotypes in gray wolves, seven of these are derived from hybridization with coyotes, four are confined to the New World, six are confined to the Old World and one is shared by both areas. Genetic differentiation among wolf populations is significant but small in magnitude. In the Old World, most localities have a single unique genotype, whereas in the New World several genotypes occur at most localities and three of the five genotypes are nearly ubiquitous. The pattern of genetic differentiation in the gray wolf contrasts with that of another large, highly vagile canid, the coyote, in which genetic differentiation among populations is not significant even among widely separated localities. We suggest that the difference between these two species reflects the rapid, recent increase in coyote numbers and expansion of their geographic range, and the coincident decline in gray wolf populations. Apparent genetic differences among extant wolf populations may be a recent phenomenon reflecting population declines and habitat fragmentation rather than a long history of genetic isolation. 相似文献
78.
Marc?Le Lann Catherine?ElleouetEmail author Fran?ois?Quentel Christian?Louis?Madec 《Environmental Chemistry Letters》2003,1(1):98-102
Cathodic adsorptive stripping voltammetry is one of the most sensitive analytical methods for ultratrace analysis. The detection
limit is usually lower than 10−9 mol/L. Most adsorptive stripping procedures have been focused on the one ligand/one analyte approach. In order to reduce
analysis time and sample volume, the possibility of simultaneously determining several metals by cathodic stripping voltammetry
using a mixture of ligands was explored, e.g., by Colombo and van den Berg (1997). Here, we describe a new procedure for quantifying
chromium and copper using 2,2′-bipyridine and 8-hydroxyquinoline (oxine). The effect of various operational parameters such
as buffer type, ligand concentration, potential and time collection were assessed and optimized. Possible interferences by
trace metals and organic matter were also investigated. Applicability for fresh water is illustrated.
Electronic Publication 相似文献
79.
In signalling interactions, animals can directly address information to a specific individual. Vocal overlapping is such a
signalling strategy used in songbirds, anurans, and insects. In songbirds, numerous studies using high rates of song overlap
to simulate an escalating situation have shown that song overlapping is perceived as a threatening signal by interacting and
by listening (eavesdropping) individuals, indicating a high social relevance of song overlapping. Here we present a playback
experiment on nocturnally singing male territorial nightingales (Luscinia megarhynchos). Using three different rates of song overlap (1, 25, or 50%), we tested whether or not lower levels of song overlapping
act as a signal of aggressive intent and if birds would increase the intensity of their response with increasing level of
song overlapping. Subjects did not vary song duration in response to the different playback treatments but increasingly interrupted
their singing with increasing overlap by the three playback treatments. The effects persisted even after the playback ceased
to overlap and switched to an alternating singing mode. These results expand on previous studies by showing that song overlapping
is interpreted as an aggressive signal even when it is used at low or moderate levels. They suggest that, within the range
tested here, increasing levels of song overlapping are perceived to be increasingly aggressive. 相似文献
80.
Gail L. Patricelli Marc S. Dantzker Jack W. Bradbury 《Behavioral ecology and sociobiology》2007,61(7):1099-1110
Studies of animal acoustic communication have found that the frequency and temporal structure of acoustic signals can be shaped
by selection for efficient communication. The directionality of acoustic radiation may also be adapted for communication,
but we know relatively little about how directionality varies with signal function, sender morphology, and the environment
in which the sound is transmitted. We tested the hypothesis that the directionality of a vocalization is adapted to its function
in communication. This hypothesis predicts that vocalizations that are directed to multiple conspecifics (e.g., advertisements
and alarms) will be relatively omnidirectional because this will maximize the number of neighbors and mates that receive the
signal, and that vocalizations directed to particular individuals will be relatively directional because this will maximize
detection of the signal by the targeted receiver and minimize eavesdropping. To test these predictions, we measured the directionality
and amplitude of red-winged blackbird (Agelaius pheoniceus) vocalizations in the field by recording vocalizations simultaneously on eight calibrated microphones encircling the bird.
We found significant variation in directionality among vocalizations. Supporting our predictions, we found that the most omnidirectional
vocalizations were those used to alert conspecifics to danger, and the most directional vocalizations are those used during
courtship and solicitation of copulation, when the costs of eavesdropping are likely to be high. These results suggest that
the directionality of red-winged blackbird vocalizations is shaped by selection for effective communication. This study is
the first to provide statistical support for the hypothesis that directionality is related to the function of a signal in
communication. 相似文献