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141.
142.
Paul Allen 《Journal of environmental science and health. Part. B》2013,48(4):549-567
Abstract The effects of cadmium and lead on chronic mercury accumulation were investigated in O. aureus. After 140 days’ exposure the accumulation of mercury in the liver, brain, gill filaments, intestine, caudal muscle, spleen, trunk kidney and eye was analysed. The exposure concentrations were 0.05, 0.10 and 0.20 mg/L for mercury alone. O. aureus was also exposed to mixtures of 0.05 mg/L mercury with lead (0.05 mg/L and 0.50 mg/L or cadmium (0.05 mg/L) and 0.10 mg/L mercury with 0.10 mg/L cadmium. In food fish, a knowledge of toxic metal accumulation patterns is of great importance because of their contribution to the human diet and, as fishmeal, to the diet of agricultural animals. The trunk kidney consistently accumulated higher concentrations of mercury than any of the other tissues investigated. 相似文献
143.
Jiří Kopáček Jan Turek Josef Hejzlar Hana Šantrůčková 《Atmospheric environment (Oxford, England : 1994)》2009,43(34):5443-5453
Precipitation and throughfall fluxes of major ions, nutrients (C, N, P), and metals (Al, Fe, Mn), and the chemical composition of litter fall and living plant tissue in Norway spruce stands (the Bohemian Forest; Czech Republic), were used to evaluate how microbial processes and decay of plant tissue in canopies influence canopy leaching (CL) of elements. Proton exchange for Mg2+, Ca2+, and K+ in decaying biomass and co-transport of Ca2+ and K+ out of plant cells with organic acid anions were the most likely processes contributing to CL of base cations. The CL of total P and N (and also NO3?) was minor. Important proportions of the N and P mineral forms were transformed to organic forms by microbial processes (primary and bacterial production), with the respective CL of ?13.9 and 16.4 mmol m?2 yr?1 for NH4+ and organic N, and ?0.33 and 0.22 mmol m?2 yr?1 for dissolved reactive P (DRP) and organic P. Most of particulate P and N in throughfall (~90%) originated from microbial DRP and NH4+ transformations, but particulate C mostly came from the fragmentation of plant tissue (58%). Among metals, CL was not observed for Al, was small for Fe (0.3 mmol m?2 yr?1), and greatest for Mn (0.9 mmol m?2 yr?1) due to leaching from decaying tissue by acidic precipitation. 相似文献
144.
Hana Patzenhauerová Josef Bryja Radim Šumbera 《Behavioral ecology and sociobiology》2010,64(5):757-767
The African mole-rats (Bathyergidae, Rodentia) are subterranean rodents that have evolved a wide range of social organisations
varying from solitary to eusocial. Due to some unusual features of their breeding and social systems, much attention has been
focused on social species, with solitary species being virtually ignored. Here, we present the first genetic study on the
mating system of any solitary mole-rats, the silvery mole-rat (Heliophobius argenteocinereus) - a species which is assumed to be monogamous. Microsatellite markers were used to analyse the mating system and the kinship
structure in populations in southern Malawi. Isolation by distance between individuals was apparent in two studied populations,
but not in the third, probably, as a result of barriers limiting dispersal in the latter population. Polygyny was found to
be a mating system in this population, where a strongly female-biased adult sex ratio was present. In this case, large distances
between the burrow systems of mating partners exclude the possibility of belowground searching for mates, suggesting that
the males might seek females aboveground. Interestingly, among analysed litters from various localities, one multiple-sired
litter was found. Therefore, the results suggest that the mating system in potentially monogamous solitary subterranean rodents
may be much more variable than expected and can differ among populations. 相似文献
145.
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147.
Anna Francová Vladislav Chrastný Hana Šillerová Jana Kocourková Michael Komárek 《Environmental monitoring and assessment》2017,189(9):478
This study is a continuation of our preceding research identifying suitable environmental samples for the tracing of atmospheric pollution in industrial areas. Three additional types of environmental samples were used to characterise contamination sources in the industrial area of Ostrava city, Czech Republic. The region is known for its extensive metallurgical and mining activities. Fingerprinting of stable Pb isotopes was applied to distinguish individual sources of anthropogenic Pb. A wide range of 206Pb/207Pb ratios was observed in the investigated samples: 206Pb/207Pb = 1.168–1.198 in mosses; 206Pb/207Pb = 1.167–1.215 in soils and 206Pb/207Pb = 1.158–1.184 in tree cores. Black and brown coal combustion, as well as metallurgical activities, is the two main sources of pollution in the area. Fossil fuel burning in industry and households seems to be a stronger source of Pb emissions than from the metallurgical industry. Concentration analyses of tree rings showed that a significant increase in As concentrations occurred between 1999 and 2016 (from 0.38 mg kg?1 to 13.8 mg kg?1). This shift corresponds to the use of brown coal from Bílina, Czech Republic, with an increased As concentration. The burning of low-quality fuels in households remains a problem in the area, as small ground sources have a greater influence on the air quality than do industrial sources. 相似文献
148.
Zdenka Valová Hana Hudcová Kevin Roche Jana Svobodová Ilja Bernardová Pavel Jurajda 《Environmental monitoring and assessment》2013,185(4):3359-3368
We examined the relationship between muscle and scale mercury (Hg) and lead (Pb) concentrations in chub Squalius cephalus L. from six riverine sites in the Czech Republic in order to determine whether scale analysis alone could provide a nonlethal and convenient method for prediction of heavy metal concentration in muscle tissue. Our results confirm tissue-specific heavy metal accumulation in chub, with Hg tending to accumulate primarily in muscle tissue and Pb in scales. We found no significant relationship, however, for concentrations of either Pb or Hg between muscle tissue and scales of chub. Our results indicate that scales cannot be used for predicting heavy metal contamination in muscle of chub and we recommend, therefore, that muscle biopsy methods continue as the preferred method of analysis. 相似文献
149.
Allen S. Lefohn Alan A. Lucier 《Journal of the Air & Waste Management Association (1995)》2013,63(5):694-701
Ambient O3 exposures have reduced growth rates of tree genotypes in some areas of the United States. For characterizing O3 exposures in forested areas, data from primarily population-oriented sites have been used. It has been speculated that exposures calculated from population-oriented sites provide estimates greater than those that would actually be experienced in the majority of forested areas. Accordingly, we compared 1988 O3 data from three remote forested sites with data from several population-oriented monitoring sites in and around the mid? and southern Appalachian Mountains. The number of hours ≥0.08 ppm was lower at the remote forested sites than at the nearby population-oriented locations. In addition, we characterized the temporal variability of O3 exposures in forested regions of the United States and Canada for the period 1978-1988. We found that the years of highest O3 exposure in the eastern United States during 1978-1988 were 1978, 1980, 1983, and 1988, with 1988 being the worst year in four of seven eastern forest regions. In 1988, the Whiteface Mountain summit site (1483 m) experienced approximately 10 percent more hourly average concentrations ≥0.08 ppm than in the second highest O3 exposure year (i.e., 1979). Consistently throughout the 11-year period, the highest O3 exposures at the Whiteface Mountain site occurred during the late evening and early morning hours, with the result that the longterm 7-h (0900-1559h) exposure index could not distinguish those years in which the highest exposures occurred from those in which the lowest occurred. Similar to the Whiteface Mountain site, two high-elevation Shenandoah National Park sites experienced their highest O3 exposures in 1988. With the exception of 1986, the lower elevation site (Dickey Ridge) consistently experienced more frequent occurrences of hourly average concentrations ≥0.08 ppm than the higher elevation site (Big Meadows). 相似文献
150.
P.L. Livingstone K. Magliano K. Gürer P.D. Allen K.M. Zhang Q. Ying B.S. Jackson A. Kaduwela M. Kleeman L.F. Woodhouse K. Turkiewicz L.W. Horowitz K. Scott D. Johnson C. Taylor G. O'Brien J. DaMassa B.E. Croes F. Binkowski D. Byun 《Atmospheric environment (Oxford, England : 1994)》2009,43(37):5971-5977
We investigated a two-week episode with high PM concentrations in California Central Valley during the Christmas–New Year of 2000–2001 using a modeling system that consists of a computationally efficient, 3-D photochemical–microphysical transport model, a mesoscale meteorological model, emission models, and an evaluation package. One hundred simulations were conducted with fine resolutions and observational constraints, to reproduce spatial and temporal features of observed PM concentrations and to understand the formation mechanism of the episode. Simulated PM concentrations consist of secondary inorganic components, mainly ammonium nitrate, and total carbon in areas with elevated concentrations in the accumulation mode, and consist of mainly dust and sea salt in the coarse mode. Simulated oxidants and nitrate were significantly elevated over the valley, and the latter showed much less amplitude than the former. Simulated PM concentrations were evaluated with observations systematically with spatially and temporally paired method, a more restrictive multivariate method (NMFROC), and a more flexible “gradient evaluation” method. The paired evaluation shows that high correlation coefficient (R = ~0.8) and low fractional error (FE = ~0.1) could be achieved at stations with elevated 24-h concentration of PM in the accumulation mode in some simulations. The NMFROC method was used to extract useful information from seemingly failed simulations. A “gradient evaluation” method is introduced here to extract additional information from simulations. We found that emission reductions of NOx and AVOC showed similar effects on percentage basis in different areas, and both are more effective than reducing NH3 for abating elevated concentrations of accumulation mode PM in California Central Valley during the winter episode. 相似文献