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961.
Neal Colin Reynolds Brian Neal Margaret Wickham Heather Hill Linda Pugh Bronwen 《Water, Air, & Soil Pollution: Focus》2003,3(1):119-138
A 12-year record of water quality data for runoff from a spruce forested hillslope with podzolic soils shows the impacts of conifer harvesting and replanting in relation to nitrate generation and its influence on surface water acidification. With felling, nitrate increases from a background of 18 Eq/l to about 50 Eq/l after 1 to 2 years and then declines to background levels over the next 1 to 2 years and to lower concentrations thereafter. This change is mirrored by an acidification process as manifest by a change in Gran alkalinity, acid neutralization capacity (ANC) and aluminium concentrations as well as pH. For example, Gran alkalinity and ANC, which start at negative concentrations prior to felling (about –20 and –50 Eq/l, respectively), become more negative (–30 and –100 Eq/l, respectively) at high nitrate concentrations. Correspondingly, pH decreases from about 4.7 to 4.5 and aluminium concentrations increase from about 14 to 16 M. Subsequently, the acidification is reversed as nitrate concentrations decline and after five years post-felling the system has higher pH, Gran alkalinity and ANC together with lower aluminium concentrations than even before the felling took place (the post-felling values are about 4.9, -15 Eq/l, –20 Eq/l and 7 M/l, respectively).Other determinands show clear changes over time. For example, there is a marked increase in sodium and chloride prior to and around the time of felling (200 to 300 and 230 to 400 Eq/l, respectively), with a subsequent decline in concentration to pre-felling and to lower values of around 160 and 170 Eq/l, respectively, thereafter. This change is probably associated with abnormally high inputs of sea-salts from the atmosphere during the first quarter of the year of felling, and dilution thereafter, rather than a direct consequence of the felling activity itself: this change in sea salt loading has had an impact on stream acidity. Dissolved organic carbon and iron also change with concentrations increasing over time (60 to 200 and 1.0 to 1.5 M/l, respectively) and this mirrors a general pattern observed across the Plynlimon catchments irrespective of whether or not there has been felling activity.The implications of the findings are discussed in relations to environmental management and hydrochemical processes. 相似文献
962.
A high performance liquid chromatography method for determination of gas-phase hydrogen peroxide in ambient air using Fenton's chemistry 总被引:1,自引:0,他引:1
A new method for determination of hydrogen peroxide in atmospheric samples is described. Cryogenically collected H2O2 is reacted with sodium salicylate in the presence of Fe(2+) to produce dihydroxybenzoate, which is separated from the reaction mixture by high performance liquid chromatography and detected by UV absorption. Measurements of atmospheric H2O2 were conducted in Las Vegas, NV from June 1999 to December 1999 to evaluate and characterize the method. Measured mixing ratios of H2O2 (there were also non-detects) ranged from 0.012 to 2.74 ppbv, with expected correlations to primary gaseous pollutants and strong seasonal variation consistent with a photochemically derived species. It was concluded that the method is easy to use and has sufficient sensitivity and selectivity to be useful in atmospheric monitoring. 相似文献
963.
Brian A. Hazlett 《Behavioral ecology and sociobiology》1980,6(3):177-184
Summary The patterns of shell exchange in three species of hermit crabs which overlap in distribution and shell use were observed in the laboratory. Crabs showed no tendency to initiate more exchanges with conspecifics as compared with nonconspecific individuals and there were no specific size dominance effects. Lack of common communicatory patterns betweenClibararius vittatus andPagurus pollicaris was correlated with minimal actual exchange, whilePagurus impressus exchanged with both species and executed patterns in common with both. The pattern of shell exchanges and preferences indicated that, in some cases, both individuals may gain in interspecific exchanges. 相似文献
964.
965.
966.
Brian M. Snyder Ronald M. Dennis Mary J. S. Roth Ramesh Krishnan Harry W. Parker 《补救:环境净化治理成本、技术与工艺杂志》1995,6(1):69-80
The Palmerton Zinc Site is a Superfund site in Palmerton, Pennsylvania. Its former mineral processing operations have contaminated nearby wells and soils with zinc and cadmium. Preliminary analysis of soil and dust sampling conducted in May 1991 has revealed that the dust poses a potential threat to human health. Based on the results of a previous study, which showed a high percentage of silt and clay in soils from Palmerton residential properties, it was concluded that soil washing is not likely to be a viable method to treat the soil and dust contamination in Palmerton. However, since the completion of this study, a soil-washing process for “unwashable” clays and silts has been developed. A residential soil sample from Palmerton, which had low concentrations of arsenic, cadmium, and lead, and a somewhat high concentration of zinc, was washed in a bench-scale version of this process. The results showed that the new soil-washing process for “unwashable” clays and silts may be a viable method to treat the soil and dust contamination in Palmerton, depending on the soil quality criteria concentrations selected for site cleanup. 相似文献
967.
Fluorescence in situ hybridization (FISH) of chromosome-specific probes to interphase nuclei can rapidly identify aneuploidies in uncultured amniotic fluid cells. Using DNA probe sets specific for chromosomes 13, 18, 21, X, and Y, we have identified 14 fetuses where the hybridization pattern was consistent with a triploid chromosome constitution. In each case, the identification of fetal abnormalities by ultrasound examination initiated a request for rapid determination of ploidy status via prenatal FISH analysis of uncultured amniocytes. FISH produced a three-signal pattern for the three autosomes in combination with signals indicating an XXX or XXY sex chromosome complement. This hybridization pattern was interpreted to be consistent with triploidy. Results were reported to the physician within 2 days of amniocentesis and subsequently confirmed by cytogenetics. These cases demonstrate the utility of FISH for rapid prenatal identification of triploidy, particularly when fetal abnormalities are seen with ultrasonographic examination. 相似文献
968.
Brian A. Hazlett 《Behavioral ecology and sociobiology》1989,25(2):119-128
Summary The reproductive behavior of two species of diogenid hermit crabs was studied in Hawaii. In the shell generalist, Clibanarius zebra, male reproductive success varied little with size, although the largest males were less successful in obtaining copulations than were medium-large males. Male and female size were positively correlated, in successful pairs, thus larger males had the potential to fertilize more eggs when they were successful in obtaining a copulation. Female fecundity in C. zebra was not affected by species of gastropod shell inhabited once female size was taken into account. Male copulatory success was very strongly influenced by the species of gastropod shell inhabited. Males in Trochus or Nerita shells had greatly reduced reproductive success compared to males in Turbo or Nassarius shells. This result was due both to (1) males in Trochus especially dropping and otherwise poorly handling females during precopulatory behavior and (2) females not responding to precopulatory behavior patterns executed by males in Trochus and Nerita. Transferring males from good to bad shapes of shells and vice versa showed that male success was a function of shell type inhabited and not some correlated feature of the crabs. In the shell specialist, Calcinus seurati, which is found primarily in Nerita shells as an adult, males in Nerita shells were quite successful in obtaining copulations. 相似文献
970.
Tapping the leakages: Methane losses, mitigation options and policy issues for Russian long distance gas transmission pipelines 总被引:1,自引:0,他引:1
Stefan Lechtenbhmer Carmen Dienst Manfred Fischedick Thomas Hanke Roger Fernandez Don Robinson Ravi Kantamaneni Brian Gillis 《International Journal of Greenhouse Gas Control》2007,1(4):387-395
The Russian natural gas industry is the world's largest producer and transporter of natural gas. This paper aims to characterize the methane emissions from Russian natural gas transmission operations, to explain projects to reduce these emissions, and to characterize the role of emissions reduction within the context of current GHG policy. It draws on the most recent independent measurements at all parts of the Russian long distance transport system made by the Wuppertal Institute in 2003 and combines these results with the findings from the US Natural Gas STAR Program on GHG mitigation options and economics.With this background the paper concludes that the methane emissions from the Russian natural gas long distance network are approximately 0.6% of the natural gas delivered. Mitigating these emissions can create new revenue streams for the operator in the form of reduced costs, increased gas throughput and sales, and earned carbon credits. Specific emissions sources that have cost-effective mitigation solutions are also opportunities for outside investment for the Joint Implementation Kyoto Protocol flexibility mechanism or other carbon markets. 相似文献