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31.
Method: A statewide telephone survey of Michigan drivers and former drivers aged 65 and older collected information on transportation mode choices, experience with alternatives to driving, and whether drivers planned for when they could no longer drive. Results: Results showed that most older adult households owned at least one automobile, and that the automobile was the primary mode of transportation. Most former drivers obtained rides from relatives and friends. Use of public transportation was low, and some seniors were not aware of available public transportation services. Older drivers did not plan for driving cessation. Over half the drivers who perceived a likelihood of driving problems within 5 years expected to keep driving beyond 5 years. Impact on industry: Because of their lifelong reliance on the automobile, their desire to drive themselves, and their lack of experience with public transportation, efforts to enhance the mobility of older people should consider this background while alternatives to the personal automobile are developed. 相似文献
32.
ESTROM—a Romanian–Swiss research programme 总被引:1,自引:0,他引:1
Hua L Wu W Liu Y McBride MB Chen Y 《Environmental science and pollution research international》2009,16(1):1-9
Background, aim, and scope Composting is an effective treatment process to realize sludge land application. However, nitrogen loss could result in the
reduction of nutrient value of the compost products and the stabilization effect of composting on heavy metal concentration
and mobility in sludge has been shown to be very limited.
Materials and methods Laboratory-scale experiments were carried out to investigate the effects of bamboo charcoal (BC) on nitrogen conservation
and mobility of Cu and Zn during sludge composting.
Results The result indicated that the incorporation of BC into the sludge composting material could significantly reduce nitrogen
loss. With 9% BC amendment, total nitrogen loss at the end of composting decreased 64.1% compared with no BC amendment (control
treatment). Mobility of Cu and Zn in the sludge may also have been lessened, based on the decline in diethylenetriaminepentaacetic
acid-extractable Cu and Zn contents of composted sludge by 44.4% and 19.3%, respectively, compared to metal extractability
in the original material.
Discussion Ammonia adsorption capability of BC might be the main reason for the retention of nitrogen in sludge composting materials.
Decrease of extractable Cu2+ and Zn2+ in the composting material mainly resulted from the adsorption of both metals by BC.
Conclusions Incorporation of BC into composting material could significantly lessen the total nitrogen loss during sludge composting.
Mobility of heavy metals in the sludge composting material could also be reduced by the addition of BC.
Recommendations and perspectives Bamboo charcoal could be an effective amendment for nitrogen conservation and heavy metal stabilization in sludge composts.
Further research into the effect of BC-amended sludge compost material on soil properties, bioavailability of heavy metals,
and nutrient turnover in soil needs to be carried out prior to the application of BC-sludge compost in agriculture. 相似文献
33.
M.J. Sánchez‐Martín T. Crisanto M. Arienzo M. Sánchez‐Camazano 《Journal of environmental science and health. Part. B》2013,48(3):473-484
Abstract The mobility of seven pesticides in a chromic cambisol soil was studied by soil thin layer chromatography. Pesticide mobilities were determined by means of conventional autoradiographs of the chromatograms, as well as from sequential series of curves and images of the pesticide spots provided by a linear analyser. The R f values obtained from the autoradiographs and those provided by the linear analyser were quite consistent. Based on such values, pesticide mobility decreased in the following order: acephate > fluometuron > atrazine > ethofumesate > metolachlor > diazinon > glyphosate. According to the mobility scale proposed by Helling and Turner (1968), acephate is highly mobile; atrazine, fluometuron, ethofumesate and metolachlor are moderately mobile; diazinon is slightly mobile; and glyphosate is immobile. The images provided by the linear analyser allow to determine the R f values for the zones of maximum activity in the pesticide spots (R f max), as well as the activities of different spot zones and those corresponding to R f and R f max. The results obtained show the image analyser to provide more expeditious R f measurements from the chromatograms and open up new prospects for using soil TLC to investigate pesticide mobility. 相似文献
34.
Impact of the earthworm Lumbricus terrestris (L.) on As, Cu, Pb and Zn mobility and speciation in contaminated soils 总被引:2,自引:0,他引:2
Sizmur T Palumbo-Roe B Watts MJ Hodson ME 《Environmental pollution (Barking, Essex : 1987)》2011,159(3):742-748
To assess the risks that contaminated soils pose to the environment properly a greater understanding of how soil biota influence the mobility of metal(loid)s in soils is required. Lumbricus terrestris L. were incubated in three soils contaminated with As, Cu, Pb and Zn. The concentration and speciation of metal(loid)s in pore waters and the mobility and partitioning in casts were compared with earthworm-free soil. Generally the concentrations of water extractable metal(loid)s in earthworm casts were greater than in earthworm-free soil. The impact of the earthworms on concentration and speciation in pore waters was soil and metal specific and could be explained either by earthworm induced changes in soil pH or soluble organic carbon. The mobilisation of metal(loid)s in the environment by earthworm activity may allow for leaching or uptake into biota. 相似文献
35.
36.
Two challenges persist in the applications of nanoscale zero-valent iron(nZVI) for environmental remediation and waste treatment: limited mobility due to rapid aggregation and short lifespan in water due to quick oxidation. Herein, we report the nZVI incorporated into mesoporous carbon(MC) to enhance stability in aqueous solution and mobility in porous media. Meanwhile, the reactivity of nZVI is preserved thanks to high temperature treatment and confinement of carbon framework. Small-sized(~16 nm) nZVI nanoparticles are uniformly dispersed in the whole carbon frameworks. Importantly, the nanoparticles are partially trapped across the carbon walls with a portion exposed to the mesopore channels. This unique structure not only is conductive to hold the nZVI tightly to avoid aggregation during mobility but also provides accessible active sites for reactivity. This new type of nanomaterial contains ~10 wt% of iron. The nZVI@MC possesses a high surface area(~ 500 m~2/g) and uniform mesopores(~ 4.2 nm) for efficient pollutant diffusion and reactions. Also, high porosity of nZVI@MC contributes to the stability and mobility of nZVI. Laboratory column experiments further demonstrate that nZVI@MC suspension(~4 g Fe/L) can pass through sand columns much more efficiently than bare nZVI while the high reactivity of nZVI@MC is confirmed from reactions with Ni(II). It exhibits remarkably better performance in nickel(20 mg/L) extraction than mesoporous carbon, with 88.0% and 33.0%uptake in 5 min, respectively. 相似文献
37.
Measuring heavy metal migration rates in a low-permeability soil 总被引:2,自引:0,他引:2
Heavy metals at high concentrations are often toxic to living organisms, and their environmental toxicity depends on soil
properties. It has long been thought that in clay-rich, low-permeability soils, heavy metals are bound to soil particles,
and thus there are only few toxicity risks. This study questioned this perception and tested heavy metal mobility in such
a soil, of the London Clay series, using a benchtop centrifuge. Soil columns were placed in the centrifuge and were infiltrated
with solutions of Cu, Ni and Zn ions, while the centrifuge was running at three different gravity levels, at 5,280, 2,600
and 1,300 gravities. The measured rates of migration of Cu, Ni and Zn ions were extrapolated down to 1 gravity, which represents
field conditions, the conditions for which an assessment of risk due to metal toxicity would be needed. It was found that
heavy metal movement was significant in London Clay, Ni being the most mobile metal in the study, followed by Zn and then
Cu ions. Centrifuge infiltration tests were proven to be a valuable tool in the study and quantification of metal mobility
in low-permeability soil, because they were easy to run and precise in predicting metal movement in London Clay.
Electronic Publication 相似文献
38.
株洲市某交通干道夏季细颗粒物分布特征及相关因素 总被引:1,自引:0,他引:1
2014年夏季采用扫描电迁移率粒径谱仪,选取株洲市某交通干道附近,对其环境细颗粒物进行连续测量,并统计干道的车流量。实验结果表明:环境中的细颗粒物数浓度呈双峰分布,峰值一般出现在9.47~17.5、98.2~121.9 nm粒径段,晴天和雨天不同粒径段的细颗粒物数浓度的波动性不一致,降水过程对细颗粒有一定的去除作用。结合所观测的机动车流量和所排放的细颗粒物粒径谱,分析其与细颗粒物浓度之间的关系,可初步判断该环境中爱根核模态的细颗粒物来源于机动车排放。 相似文献
39.
The degradation intermediates of phenanthrene (PHE) may have increased health risks to organisms than PHE. Therefore, environmental fate and risk assessment studies should take into considerations of PHE degradation products. This study compared the sorption properties of PHE and its degradation intermediates, 9,10-phenanthrenequinone (PQN) and 9-phenanthrol (PTR) in soils, sediments and soil components. A relationship between organic carbon content (fOC) and single-point sorption coefficient (log Kd) was observed for all three chemicals in 10 soils/sediments. The large intercept in the log fOC − log Kd regression for PTR indicated that inorganic fractions control PTR sorption in soils/sediments. No relationship between specific surface area and Kd was observed. This result indicated that determination of surface area based on gas sorption could not identify surface properties for PHE, PQN, and PTR sorption and thus provide limit information on sorption mechanisms. The high sorption and strong nonlinearity (low n values) of PTR in comparison to PHE suggested that the mobility of PTR could be lower than PHE. Increased mobility of PQN compared with PHE may be expected in soils/sediments because of PQN lower sorption. The varied sorption properties of the three chemicals suggested that their environmental risks should be assessed differently. 相似文献
40.
Metal (Cu, Cd and Zn) removal and stabilization during multiple soil washing by saponin 总被引:10,自引:0,他引:10
The influence of multiple saponin washing on copper, cadmium and zinc removal and stability in three types of soils (loamy sand, loam, silty clay) was investigated. Distribution of metals and their mobility measured as the ratio of exchangeable form to the sum of all fractions in soils was differential. After single washing the highest efficiency of metal removal was obtained in loamy sand (82-90%) and loam (67-88%), whereas the lowest in silty clay (39-62%). In loamy sand and loam metals had higher mobility factors (44-61% Cu, 60-76% Cd, and 68-84% Zn) compared to silty clay (9% Cu, 28% Cd and 36% Zn). Triplicate washing led to increase both efficiency of metal removal and percentage content of their stable forms.In consequence, fractional patterns for metals before and after treatment changed visibly as a result of their redistribution. Based on the redistribution index, the most stable metal (mainly in residual and organic fractions) after triplicate washing was Cu in loamy sand and loam. For silty clay contaminated with Cd, effective metal removal and its stabilization required a higher number of washings. 相似文献