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61.
Fatih Ilhan Kubra Ulucan-Altuntas Yasar Avsar Ugur Kurt Arslan Saral 《Frontiers of Environmental Science & Engineering》2019,13(5):73
62.
Influence of water circulation rate on in situ measurements of benthic community respiration 总被引:3,自引:0,他引:3
W. R. Boynton W. M. Kemp C. G. Osborne K. R. Kaumeyer M. C. Jenkins 《Marine Biology》1981,65(2):185-190
The relationship between water circulation rate and benthic community respiration was investigated using in situ chambers fitted with variable speed pumps. A strong, positive relationship was exhibited for three estuarine study sites which represented a broad spectrum of sediment characteristics. Both aerobic respiration (65–90% of the total sediment oxygen demand, SOD) and chemical oxygen demand, COD (10–35%) increased with stirring of the overlying waters at velocities up to 20 cm s-1. Contrary to the notion that COD accounts for any increase in SOD at velocities which initiate sediment resuspension, we observed that aerobic respiration was also stimulated by high velocities. We conclude that measurements of SOD in estuarine environments should be made using water circulation rates which attempt to mimic the natural environment, and that COD cannot be assumed unimportant and should be measured directly.Supported by National Science Foundation Grant SMI 78-03130, Md. Dept. of Natural Resources, MPPSP P2-72-02 (B)Contribution No. 1137, Center for Environmental and Estuarine Studies of the University of Maryland 相似文献
63.
Masami Fujiwara Kurt E. Anderson Michael G. Neubert Hal Caswell 《Environmental and Ecological Statistics》2006,13(2):183-197
We present a new method for estimating a distribution of dispersal displacements (a dispersal kernel) from mark-recapture
data. One conventional method of calculating the dispersal kernel assumes that the distribution of displacements are Gaussian
(e.g. resulting from a diffusion process) and that individuals remain within sampled areas. The first assumption prohibits
an analysis of dispersal data that do not exhibit the Gaussian distribution (a common situation); the second assumption leads
to underestimation of dispersal distance because individuals that disperse outside of sampling areas are never recaptured.
Our method eliminates these two assumptions. In addition, the method can also accommodate mortality during a sampling period.
This new method uses integrodifference equations to express the probability of spatial mark-recapture data; associated dispersal,
survival, and recapture parameters are then estimated using a maximum likelihood method. We examined the accuracy of the estimators
by applying the method to simulated data sets. Our method suggests designs for future mark-recapture experiments.
Received: January 2004 / Revised: July 2005 相似文献
64.
65.
Kurt Schubert 《Die Naturwissenschaften》1954,41(10):231-231
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68.
Data for eight reservoirs in the South Pennines covering the period 1980-98, and for 1988-98 at the River Etherow Acid Waters Monitoring Network site, have been analysed for temporal trends using the Seasonal Kendall test. Rising trends in pH were identified at seven of the eight reservoirs, generally accompanied by declining aluminium levels. Nitrate concentrations have, however, increased sharply at the two reservoirs for which adequate data were available. Data for a wider range of determinands at the Etherow suggest that pH increases in the region can be attributed to declining sulphate concentrations, as a result of reductions in sulphur deposition. Nitrate concentrations have again increased at this site. Results are significant in a national context in that pH recovery, although widely believed to have taken place in the UK since the 1970s, has rarely been shown to have occurred. For the South Pennine region, which has been severely acidified by historically high acid deposition levels, there have clearly been improvements over the last 18 years, although many surface waters remain acidic. Observed trends for nitrate suggest that some of the pH recovery resulting from reduced sulphur deposition may have been offset by nitrogen saturation in the region, due in part to continued high levels of nitrogen deposition. 相似文献
69.
The porous polymers Amberlite XAD-2 and XAD-7 were evaluated for the sampling of ethylene glycol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol and 2-ethoxyethyl acetate in work-room air. Using diethyl ether desorption, these adsorbents were found excellent for the compounds studied. 相似文献
70.
Dioxins and furans were detected in emissions from eight medical waste incinerators tested in California. Total uncontrolled emissions ranged from 363 to 11, 811 nanograms per dry standard cubic meter. The most effective of three wet scrubbers achieved an emissions control efficiency of 95 percent for total PCDD and PCDF. A baghouse was less than 30 percent efficient in removing PCDD and PCDF from the incinerator emissions. 相似文献