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José Roberto Ferreira 《Ambio-人类环境杂志》2003,32(1):47-51
引言 莫日-瓜苏河位于纳斯吉拉斯州,海拔高1450m.流淌470km后,该河流注入圣保罗州的帕尔杜河.其流域总面积为1400km2,其中有86%位于圣保罗州,包括一个工业化地区[1]. 相似文献
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Most harvestmen are nocturnal, nonacoustical, and nonvisual arthropods. They have a pair of exocrine glands on the cephalothorax that produce defensive volatile secretions. We investigated in the field the possible alarm effect of these secretions in the gregarious harvestman Goniosoma aff. proximum. A cotton swab soaked with the species' own exudate (treatment), or with water (control), was held 1-2 cm from the center of harvestmen aggregations. The results showed that the gland secretion elicits an alarm response in Goniosoma: whereas 73.3% of the aggregations dispersed after being stimulated with the gland exudate, only 3.3% responded to the water control. Respondent groups are larger than nonrespondent groups, and the time of reaction to the secretion was inversely related to group size. This is the first demonstration of a chemically-mediated alarm effect in harvestmen. The alarm response in gregarious harvestmen has possibly evolved as a by-product of a primarily defensive reaction in the context of predator avoidance. The discovery of this novel function of scent-gland secretion is meaningful in view of the widespread occurrence of gregarious habit among species of the order Opiliones. 相似文献
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Brood desertion is a life history strategy that allows parents to minimize costs related to parental care and increase their future fecundity. The harvestman Neosadocus maximus is an interesting model organism to study costs and benefits of temporary brood desertion because females abandon their clutches periodically and keep adding eggs to their clutches for some weeks. In this study, we tested if temporary brood desertion (a) imposes a cost to caring females by increasing the risk of egg predation and (b) offers a benefit to caring females by increasing fecundity as a result of increased foraging opportunities. With intensive field observations followed by a model selection approach, we showed that the proportion of consumed eggs was very low during the day and it was not influenced by the frequency of brood desertion. The proportion of consumed eggs was higher at night and it was negatively related to the frequency of brood desertion. However, frequent brood desertion did not result in higher fecundity, measured both as the number of eggs added to the current clutch and the probability of laying a second clutch over the course of the reproductive season. Considering that harvestmen are sensitive to dehydration, brood desertion during the day may attenuate the physiological stress of remaining exposed on the vegetation. Moreover, since brood desertion is higher during the day, when egg predation pressure is lower, caring females could be adjusting their maternal effort to the temporal variation in predation risk, which is regarded as the main cost of brood desertion in ectotherms. 相似文献
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Total mercury content was evaluated in water and suspended sediment samples of the Moji-Gua?u river and in water and bottom sediment of its 3 marginal lagoons (Catingueiro, Barrinha, and Rio das Pedras), located downstream of the sampling point in the main channel. In all situations, low Hg concentrations were found in suspended and bottom sediments. Aluminum was used as a geochemical tracer to normalize the Hg concentrations in the sediment cores from the Rio das Pedras lagoon (r = 0.92). It was estimated that the Moji-Gua?u river transports up to 19 kg Hg yr(-1), 65% in the dissolved form and 35% adsorbed onto particulate matter. Following an acute toxic stage observed in the years 1970-1980, the basin has been restored to its original conditions mainly by natural recovery and a general reduction in Hg input to the ecosystem. 相似文献
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Although studies classify the polygynous mating system of a given species into female defense polygyny (FDP) or resource defense
polygyny (RDP), the boundary between these two categories is often slight. Males of some species may even shift between these
two types of polygyny in response to temporal variation in social and environmental conditions. Here, we examine the mating
system of the Neotropical harvestman Acutisoma proximum and, in order to assess if mate acquisition in males corresponds to FDP or RDP, we tested four contrasting predictions derived
from the mating system theory. At the beginning of the reproductive season, males fight with other males for the possession
of territories on the vegetation where females will later oviposit, as expected in RDP. Females present a marked preference
for specific host plant species, and males establish their territories in areas where these host plants are specially abundant,
which is also expected in RDP. Later in the reproductive season, males reduce their patrolling activity and focus on defending
individual females that are ovipositing inside their territories, as what occurs in FDP. This is the first described case
of an arachnid that exhibits a shift in mating system over the reproductive season, revealing that we should be cautious when
defining the mating system of a species based on few observations concentrated in a brief period.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
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Visigalli Simone Turolla Andrea Bellandi Giacomo Bellucci Micol Clagnan Elisa Brusetti Lorenzo Jia Mingsheng Di Cosmo Roberto Menin Glauco Bargna Martina Bergna Giovanni Canziani Roberto 《Environmental science and pollution research international》2021,28(34):46643-46654
Environmental Science and Pollution Research - Digital textile printing (DTP) is a game-changer technology that is rapidly expanding worldwide. On the other hand, process wastewater is rich in... 相似文献
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Atmospheric levels of aldehydes and BTEX and their relationship with vehicular fleet changes in Rio de Janeiro urban area 总被引:1,自引:0,他引:1
A comprehensive monitoring campaign to assess aldehydes and BTEX concentrations was performed during 12 months, in the Tijuca district (Rio de Janeiro), an area with commercial activities and a high flux of vehicles. The mean concentrations of formaldehyde and acetaldehyde were 151 and 30 ppb, respectively. The high formaldehyde/acetaldehyde ratio was attributed to extensive use of compressed natural gas (CNG). The number of CNG vehicles in the metropolitan Region of Rio de Janeiro increased from 23000 in January 2001 to 161000 in January 2005. Monitoring data show that, for the same period, methane and formaldehyde concentrations increased while NO(x) and CO levels diminished. Mean concentrations for benzene, toluene, ethylbenzene, m,p-xylene and o-xylene, were 1.1, 4.8, 3.6, 10.4 and 3.0 micro gm(-3), respectively. Benzene and toluene concentrations were lower than the values determined in 1996, for the same location. The levels of ethylbenzene and xylenes determined in this work are similar to values obtained in 1996. This fact may be explained as a consequence of changes in the gasoline composition. 相似文献
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Laerte I. Sznelwar Fausto L. Mascia Mauro Zilbovicius Glauco Arbix 《International journal of occupational safety and ergonomics》2013,19(2):291-301
AbstractThe discussion developed in this paper is based on the results of an ergonomic work analysis carried out with attendants at call centers. Some critical issues and difficulties, like working pace, inadequate tools and workstations, and software inadequacies were detected in working situations. Operator-customer interactions are presented, attempting to put in evidence working constraints, working conditions, and their connection with health problems.The main conclusion is that serving clients, especially when the job is to provide information, is not a simple task, as information is not always available in the computerized system and is completely fragmented. The scope of workers’ actions is very restricted and complicated and recurrent requests are redirected to others. Workers (individually or as groups) have limited possibilities to make adjustments to be able to give more adequate and personalized treatment to clients and, at the same time, to work in a less stressful environment. In periods of increased workload and work intensification, the situation is very much favorable to the incidence of health disorders, such as work related musculoskeletal disorders (WMSD) and others. Some suggestions to improve the work situation are discussed. 相似文献