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41.
William B. Petersen Rodney Allen 《Journal of the Air & Waste Management Association (1995)》2013,63(8):826-833
Carbon monoxide exposures to commuters were simulated in a 5-day study in Los Angeles County. Exposures were determined by measuring CO in three vehicles as they traveled typical commuter routes. The data collected during this study include measurements of vehicle speed and CO measurements in the interior and exterior of the three vehicles during the morning and evening peak traffic periods. In addition, hourly averaged CO measurements were taken from eight south coastal Air Quality Management District fixed-site monitoring stations and six California Department of Transportation vans in the proximity of the commuter routes. These data were used to investigate the relationship of CO exposures to meteorological parameters, fixed-site monitors, and traffic conditions. The average ratio of interior CO concentrations to exterior CO concentrations was 0.92. Concentrations inside and outside the vehicles remained about the same even when the vehicles were driven with vents closed and windows up. Smoking was not permitted in the vehicles during the study. The average ratio of the hour average CO concentrations in the vehicles to fixed-site measurements was 3.9. However, this ratio decreases with increasing ambient CO levels. Although CO levels in the vehicles frequently exceeded 40 ppm and sometimes exceeded 60 ppm, the hour average CO concentrations did not exceed 35 ppm. Slow moving congested traffic is associated with higher CO levels in the vehicles than a high volume of traffic moving at a steady speed. 相似文献
42.
Water hyacinths as a resource in agriculture and energy production: a literature review 总被引:2,自引:0,他引:2
Water hyacinths are becoming a problem in lakes, ponds and waterways in many parts of the world. This paper contains a literature study of different ways to use water hyacinths, mainly in agricultural or alternative energy systems. The literature review indicated that water hyacinths can be rich in nitrogen, up to 3.2% of DM and have a C/N ratio around 15. The water hyacinth can be used as a substrate for compost or biogas production. The sludge from the biogas process contains almost all of the nutrients of the substrate and can be used as a fertiliser. The use of water hyacinth compost on different crops has resulted in improved yields. The high protein content makes the water hyacinth possible to use as fodder for cows, goats, sheep and chickens. Water hyacinth, due to its abundant growth and high concentrations of nutrients, has a great potential as fertiliser for the nutrient deficient soils of Africa and as feed for livestock. Applying the water hyacinths directly without any other processing than sun drying, seems to be the best alternative in small-scale use due to the relatively small losses of nutrients and workload required. To meet the ever-growing energy demand, biogas production could be one option but it requires investments and technological skills that would impose great problems in developing countries where the water hyacinth is often found. Composting as an alternative treatment has the advantage of a product that is easy to work into the soil compared with dried water hyacinths, because of the decomposed structure. Harvesting and transport of water hyacinths can be conducted manually on a small scale and does not require a new harvesting technique to be introduced. Transporting of fresh water hyacinths means, if used as fertiliser in amounts large enough to enhance or effect crop growth, an unreasonably large labour requirement. Based on the labour need and the limited access to technology, using dried water hyacinths, as green manure is a feasible alternative in many developing countries. 相似文献
43.
Larry Larsen Terri Morrell Gretchen Schalge Meghan Gallione Joseph Bell Kip Petersen Frederick Steiner 《Environmental management》1991,15(4):549-563
This article is the third in a series prepared to explain the Teller County growth management planning process. Once it was
determined by local decision-makers that Teller County, Colorado, would pursue a policy of directed growth, concepts based
on this policy were developed. These concepts presented visions and options for the future. Landscape plans then were developed
for Teller County and the City of Woodland Park planning area so that these options could be visualized by local leaders and
the public. The landscape plans were used as part of the ongoing citizen involvement process to inform the public about the
options for growth management. To provide even more information, detailed designs were developed for specific areas in the
county. From the landscape plan, public involvement effort, and detailed designs, specific implementation measures were identified,
discussed, and adopted. These measures included guidelines for administration, so that county and city goals could be linked
to the actual day-to-day management of development proposals.
Paper 3 in a series of 3. 相似文献
44.
Dr. Michael B. Petersen 《黑龙江环境通报》1986,6(5):363-367
A case with an uncommon heteromorphism in the centromeric region of chromosome 20, var (20) (cen, CBG 50), and a family with a pericentric inversion of chromosome 20, inv (20) (p11.23q11.21), are reported, both detected in amniotic fluid cell cultures. It appears that small pericentric inversions of chromosome 20 have a low risk of recombination. 相似文献
45.
Jaroslav Hynt Miloslav imek Petr Br
ek Sren O. Petersen 《Agriculture, ecosystems & environment》2007,120(2-4):269-279
Cattle overwintering areas common in central Europe may represent significant point sources of the important greenhouse gases, nitrous oxide (N2O) and carbon dioxide (CO2). A 2-year field study was carried out in order to estimate the emissions of N2O and CO2 from soil in a cattle overwintering area located in the southwest of the Czech Republic. The measurements were performed at three sampling locations along a gradient of animal impact (severe, moderate, slight) to test the hypothesis that emissions of CO2 and N2O are positively related to the degree of impact. In addition to CO2 and N2O fluxes determined by using non-vented manual closed chambers, soil mineral nitrogen (NH4+ and NO3−), pH and temperature were determined to assess their regulatory role and impact on gas fluxes. The overwintering area was about 4 ha and it had been used for overwintering of about 90 cows since 1995. Deposition of animal excreta resulted in a significant accumulation of nitrogen in the soil during winter, but most of the N2O was emitted during a few short periods in spring and/or in late autumn. Maximum N2O fluxes of up to 2.5 mg N2O-N m−2 h−1 were recorded at the most impacted location near the animal house, where the highest concentrations of soil mineral nitrogen also occurred. The emissions of CO2 showed a completely different pattern to those of N2O, being correlated with soil temperature; the highest emissions thus occurred in June–July, while very low fluxes were found in winter. Emission values ranged from about 0 to 700 mg C-CO2 m−2 h−1. Furthermore, the effect of animal impact on CO2 emissions was opposite to that on N2O fluxes, as the highest CO2 fluxes were mostly recorded at the least impacted location, where respiration of plants most likely increased overall CO2 production. The results show that cattle overwintering areas are important sources of greenhouse gases, including N2O and CO2. Fluxes of these two gases are, however, differently distributed over the year, which also suggests that they are controlled by different environmental and soil factors. 相似文献
46.
Power analysis as a reflexive scientific tool for interpretation and implementation of the precautionary principle in the European Union 总被引:1,自引:0,他引:1
Sanderson H Petersen S 《Environmental science and pollution research international》2002,9(4):221-226
The diversity of interpretation, the subsequent lack of implementation, and the enforcement of the precautionary principle have been important issues in the European environmental discourse for the past five years. The European Commission published a communication on the Commission's interpretation of the precautionary principle on February 2nd, 2000. However, the distinction between precaution and prevention is absent in the EU Commission's interpretation, resulting in the communication's lacking relevance for the precautionary principle. The important consequence of the precautionary concept in policy and decision-making is that it should not be based on an assumed certainty of the certainty of environmental knowledge--but rather on a certainty of the uncertainty of environmental knowledge. In other words, the regulation should, to a greater extent, be based on the management of uncertainty, and risk assessments should explicitly present and discuss related uncertainty and lack of knowledge. The management of uncertainty should be based on setting the acceptable level of risk of accepting a failure to reject the null hypothesis of no adverse effects (beta). This is done by setting the required power (1-beta) according to a socioeconomic cost-benefit analysis. Moreover, the acceptable ecological effect size (A) could also be set a priori which would have implications for the power of a study. Reversal of the burden of proof could be considered in order to resolve possible legal implications for the risk managers. 相似文献
47.
Petersen 《Die Naturwissenschaften》1922,10(17):439-440
48.
49.
Microbial growth and transport in porous media under denitrification conditions: experiments and simulations 总被引:1,自引:0,他引:1
T. P. Clement B. M. Peyton R. S. Skeen D. A. Jennings J. N. Petersen 《Journal of contaminant hydrology》1997,24(3-4)
Soil column experiments were conducted to study bacterial growth and transport in porous media under denitrifying conditions. The study used a denitrifying microbial consortium isolated from aquifer sediments sampled at the U.S. Department of Energy's Hanford site. One-dimensional, packed-column transport studies were conducted under two substrate loading conditions. A detailed numerical model was developed to predict the measured effluent cell and substrate concentration profiles. First-order attachment and detachment models described the interphase exchange processes between suspended and attached biomass. Insignificantly different detachment coefficient values of 0.32 and 0.43 day−1, respectively, were estimated for the high and low nitrate loading conditions (48 and 5 mg l−1 NO3, respectively). Comparison of these values with those calculated from published data for aerobically growing organisms shows that the denitrifying consortium had lower detachment rate coefficients. This suggests that, similar to detachment rates in reactor-grown biofilms, detachment in porous media may increase with microbial growth rate. However, available literature data are not sufficient to confirm a specific analytical model for predicting this growth dependence. 相似文献
50.
The reunification of Germany led to dramatically reduced emissions of nitrogen (N) and phosphorus (P) to the environment. The aim of the present study was to examine how these exceptional decreases influenced the amounts of nutrients carried by the Elbe River to the North Sea. In particular, we attempted to extract anthropogenic signals from time series of riverine loads of nitrogen and phosphorus by developing a normalization technique that enabled removal of natural fluctuations caused by several weather-dependent variables. This analysis revealed several notable downward trends. The normalized loads of total-N and NO3-N exhibited an almost linear trend, even though the nitrogen surplus in agriculture dropped dramatically in 1990 and then slowly increased. Furthermore, the decrease in total-P loads was found to be considerably smaller close to the mouth of the river than further upstream. Studying the predictive ability of different normalization models showed the following: (i) nutrient loads were influenced primarily by water discharge; (ii) models taking into account water temperature, load of suspended particulate matter, and salinity were superior for some combinations of sampling sites and nutrient species; semiparametric normalization models were almost invariably better than ordinary regression models. 相似文献