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571.
PROBLEM: Graduated Driver Licensing (GDL) programs vary in the United States in terms of implementation and restrictions. The State of Iowa's GDL program is assessed for its effectiveness in reducing crashes among teenage drivers. METHOD: Time series analysis was used to evaluate police documented crashes involving 16-, 17-, and 18-year-old drivers over a 10 year period, with an intervention identified at the point of GDL implementation. RESULTS: After controlling for seasonal trends and auto-correlative effects, a significant reduction in the crash rate of and 16- and 17-year-old drivers was observed due to the GDL implementation. However, there were no significant reductions in crash rates for 18-year-old drivers. DISCUSSION: The analyses suggest that the Iowa GDL program is effective in reducing the crash rates of 16- and 17-year-old drivers but the effects do not sustain for 18-year-old drivers. IMPACT ON INDUSTRY: The results suggest that the program appears to be working, however further analysis is needed to determine what factors are preventing lasting effects for these teenage drivers. 相似文献
572.
Separating the effects of organic matter-mineral interactions and organic matter chemistry on the sorption of diuron and phenanthrene 总被引:1,自引:0,他引:1
Even though it is well established that soil C content is the primary determinant of the sorption affinity of soils for non-ionic compounds, it is also clear that organic carbon-normalized sorption coefficients (K(OC)) vary considerably between soils. Two factors that may contribute to K(OC) variability are variations in organic matter chemistry between soils and interactions between organic matter and soil minerals. Here, we quantify these effects for two non-ionic sorbates-diuron and phenanthrene. The effect of organic matter-mineral interactions were evaluated by comparing K(OC) for demineralized (HF-treated) soils, with K(OC) for the corresponding whole soils. For diuron and phenanthrene, average ratios of K(OC) of the HF-treated soils to K(OC) of the whole soils were 2.5 and 2.3, respectively, indicating a substantial depression of K(OC) due to the presence of minerals in the whole soils. The effect of organic matter chemistry was determined by correlating K(OC) against distributions of C types determined using solid-state (13)C NMR spectroscopy. For diuron, K(OC) was positively correlated with aryl C and negatively correlated with O-alkyl C, for both whole and HF-treated soils, whereas for phenanthrene, these correlations were only present for the HF-treated soils. We suggest that the lack of a clear effect of organic matter chemistry on whole soil K(OC) for phenanthrene is due to an over-riding influence of organic matter-mineral interactions in this case. This hypothesis is supported by a correlation between the increase in K(OC) on HF-treatment and the soil clay content for phenanthrene, but not for diuron. 相似文献
573.
Semipermeable membrane device (SPMD) for monitoring PCDD and PCDF levels from a paper mill effluent in the Androscoggin River, Maine, USA 总被引:1,自引:1,他引:0
Paper mill effluents may contain polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) that are normally generated due to chlorinated bleaching of pulp and paper. We used the semipermeable membrane device (SPMD) to monitor PCDD/F levels upstream and downstream of a paper mill on the Androscoggin River, in Jay (ME). Following the 36 day deployment, SPMD dialysis and cleanup, the samples were analyzed by HRGC/HRMS. Total concentrations of PCDD/Fs in SPMDs (sum of all tetra-through octachlorinated congeners) ranged from 4.71 pg g(-1) to 26.26 pg g(-1). Five out of the targeted 17 toxic congeners were detected, including: 2,3,7,8-TCDF; 1,2,3,7,8-PeCDF; 2,3,4,7,8-PeCDF; 1,2,3,4,6,7,8-HpCDD and OCDD. Permeability reference compounds (PRCs) were used for in situ calibration of the SPMD sampling rate (Rs). In all sites, water concentrations were the highest for OCDD (0.081-0.103 pg l(-1)), and the lowest for 1,2,3,7,8-PeCDF (0.005-0.009 pg l(-1)). There was not a consistent pattern of upstream-downstream gradient in the PCDD/F levels. This suggested that processes other than the mill in Jay (multiple sources, river dynamics) governed the flux of PCDD/Fs in the sampling locations. The SPMD results were validated by comparison to other studies on the Androscoggin River and elsewhere, confirming the potential of the device as a useful monitoring technique for PCDD/Fs in large river systems. 相似文献
574.
Aishah S. A. K. Sharifah Hanafiah Zainal Abidin Mohamad R. Sulaiman Kheng H. Khoo Hairi Ali 《Journal of Material Cycles and Waste Management》2008,10(2):116-123
Malaysia is in dire need of alternatives to landfilling for solid waste management. Recently, landfills have faced the problems
of overfilling, overflowing of leachates leading to pollution of water resources, and uncontrolled dust emissions adversely
affecting the local environment. With the rising cost of urbanization coupled with the high rate of waste generation, one
possible method of waste treatment that is receiving particular attention by the government is incineration. Incineration
of solid waste is rather new in Malaysia, with limited usage in handling small sources of waste generation such as the municipal
solid waste (MSW) of resort islands; however, its potential in ameliorating the problems associated with solid waste treatment
may make it an attractive alternative to landfill. This article presents the results of test runs conducted to investigate
the performance of a locally designed and manufactured rotary kiln incinerator (RKI). The test runs were conducted using MSW
collected from the Shah Alam municipality. The combustion efficiency was analyzed by looking at the temperature profiles and
chemical species concentrations. To complement the combustion characteristics measurements, predictions of the air flow in
the incinerator during the process were also investigated. The overall performance of the RKI suggests that it is suitable
for treating MSW. 相似文献
575.
Markéta Julinová Marie Dvořáčková Jan Kupec Jitka Hubáčková Martina Kopčilová Jaromír Hoffmann Pavol Alexy Anna Nahálková Ida Vašková 《Journal of Polymers and the Environment》2008,16(4):241-249
Improving biodegradability of PVA/starch blends is a reality already documented by a number of works. Admittedly, mechanical
properties of products (for example, tensile strength) are somewhat worse, but suitable composition optimizing or chemical
modifying of starch may eliminate the problem to a large degree. This work is an attempt to find another potential effect
influencing biodegradability, that of technological procedure for producing films from these blends on an extruder. The procedure
with a so-called pre-extrusion step (two-stage) and dry-blend (single-stage) produced blends of slightest differences in achieved
biodegradability (virtually within limits of experimental error) in aerobic (76 vs. 79%) as well as anaerobic breakdown (48
vs. 52%). Conversely, morphological analysis exhibited superior homogeneity of films prepared by the two-stage process; their
tensile strength was also higher. 相似文献
576.
577.
Sławomir Stelmach Ryszard Wasielewski 《Journal of Material Cycles and Waste Management》2008,10(2):110-115
More than 1.1 million tons of municipal and industrial sewage sludge is produced annually in Poland. Most of this sewage sludge
is landfilled or used for recultivation and fertilization of soil. After accession of Poland to the EU, large investments
are planned for wastewater treatment, so it is expected that the amount of sewage sludge produced in Poland will grow in the
near future. It is well known that the combustion of sewage sludge is becoming a more and more popular utilization method
of such waste. Unfortunately, the current situation in Poland makes it impossible to incinerate the sewage sludge because
of a lack of incinerators. One possible solution for Poland is the co-firing of dried sewage sludge in existing coal-fired
utility boilers. This article presents results of initial Polish industrial trials of dried municipal sewage sludge and hard
coal co-combustion in an OP-230 pulverized coal boiler. Such a solution was shown to be technically viable and not to require
changes to the existing technological system. Cocombustion of sewage sludge with coal in power plants seems to be the best
solution for sludge utilization in the near future in Poland. 相似文献
578.
Jörg Luster Manoj Menon Sandra Hermle Rainer Schulin Madeleine S. Günthardt-Goerg Bernd Nowack 《Water, Air, & Soil Pollution: Focus》2008,8(2):163-176
Soil translocation for recultivation of soil removed from construction sites and for the preparation of refilled lysimeters
inevitably involves disturbance of soil structure, and, if intermediate storage is included, also drying and rewetting of
the soil. We report on an experiment with model forest ecosystems, where uncontaminated forest subsoils were covered with
non-contaminated or freshly heavy metal (mainly Zn and Cu) contaminated topsoil in large lysimeters. Monitoring of the chemical
composition of the drainage water revealed two distinct soil conditioning phases. During an initial phase of about a year
strongly elevated nitrate and sulfate concentrations occurred that were attributed to a mineralisation flush caused by the
increased accessability of mineralisable nitrogen and sulfur in destroyed aggregates. These effects were significantly larger
in lysimeters with calcareous subsoil than in those with acidic subsoil. The second phase was characterised by a gradual decrease
in dissolved organic carbon and sulfate concentrations, in particular in the acidic subsoil. This decrease may be attributed
to the depletion of pools made accessible during aggregate destruction or the formation of new aggregates. These chemical
changes had only little effects on the concentrations of copper and zinc in the drainage water. Based on our results, it can
be concluded that large refilled lysimeters can be used for many purposes without risk of compromised results, if a conditioning
phase of about 1 year with sufficiently moist soil conditions is respected. Nevertheless, gradual changes in soil chemical
characteristics still occur after this initial phase. Implications for the recultivation of sites using relocated soils are
discussed. 相似文献
579.
580.
Reiner Schroll Sabine Grundmann Ulrike Dörfler Bernhard Ruth Jean Charles Munch 《Water, Air, & Soil Pollution: Focus》2008,8(2):209-216
Several lysimeter scenarios and approaches exist to study the fate of agro-chemicals or contaminants from deposition in soil
columns. In many systems just transport and leaching of the parent compound is followed, in some systems the leaching and
transport of the metabolites is investigated as well. In more sophisticated lysimeter systems the volatilization and also
the mineralization of the applied chemicals can be additionally monitored. Depending on the lysimeter system used and on the
fact whether the applied chemicals are 14C-labeled or not, different results and various interpretations of the results might be achieved. Different lysimeter systems
are described in this paper and a real dataset of a specific lysimeter experiment was transferred and evaluated in a virtual
approach in the different lysimeter systems in order to show the advantages and disadvantages of the various systems. 相似文献