丹麦——“绿色”能源的先行者

"在平时的政治工作中,各政党总是持有异见,但是在丹麦的绿色未来上我们没有任何分歧。"——丹麦气候、能源和建设部长马丁·里德嘉德在京都议定书第二承诺期中,欧盟设定的目标是到2020年可再生能源占比达到20%。而丹麦,早在2011年就完成了这一目标,不仅如此,丹麦还计划在2020年将可再生能源比例提高到30%,并在2050年之前建立一个不含核能、完全摆脱对化石燃料依赖的能源系统,这被称为丹麦的第二次能源革命。     

博斯腾湖水文特征的变化及其合理利用

一、湖区概况博斯腾湖是我国十大湖泊之一。位于天山南坡焉耆盆地的东南部,处于该盆地的最低处,东西长55公里,南北宽25公里。当其水面高程为1048.28米时(1959年),水面面积为992平方公里,总容积为88亿立方米。湖水平均深度约8米,最深处可达14—15米(湖底最低处高程为1031米)。湖的西部、     

Analysis of trace dicyandiamide in stream water using solid phase extraction and liquid chromatography UV spectrometry

An improved method for trace level quantification of dicyandiamide in stream water has been developed. This method includes sample pretreatment using solid phase extraction. The extraction procedure (including loading, washing, and eluting) used a flow rate of 1.0 mL/min, and dicyandiamide was eluted with 20 mL of a methanol/acetonitrile mixture (V/V = 2:3), followed by pre-concentration using nitrogen evaporation and analysis with high performance liquid chromatography–ultraviolet spectroscopy (HPLC–UV). Sample extraction was carried out using a Waters Sep-Pak AC-2 Cartridge (with activated carbon). Separation was achieved on a ZIC^®-Hydrophilic Interaction Liquid Chromatography (ZIC-HILIC) (50 mm × 2.1 mm, 3.5 μm) chromatography column and quantification was accomplished based on UV absorbance. A reliable linear relationship was obtained for the calibration curve using standard solutions (R² > 0.999). Recoveries for dicyandiamide ranged from 84.6% to 96.8%, and the relative standard deviations (RSDs, n = 3) were below 6.1% with a detection limit of 5.0 ng/mL for stream water samples.     

The evolution of mass balance models of persistent organic pollutant fate in the environment

Current approaches to modelling the fate of persistent organic pollutants (POPs) in the environment have evolved in response to four dominant characteristics of these substances; namely: (1) the presence of POPs in virtually all environmental phases and the ease with which they move from one to the other requires multi-compartmental modelling. Describing transport across phase boundaries becomes as, or even more, important as quantifying transport within the phases; (2) POPs may persist in the environment for many decades. For chemicals that 'have time', concepts such as equilibrium partitioning and steady-state become more important than for short-lived substances whose fate is more controlled by the rates of transformation; (3) measuring POPs is difficult and expensive and observed concentrations of POPs are not available in high spatial or temporal resolution. Consequently, high resolution tends not to be a high priority in POP models; and (4) detrimental effects of POPs often manifest themselves in top predators, which has led to a focus on modelling biotic uptake and transfer within food chains. The task of building a POPs model is viewed as combining the four 'building blocks' of partitioning, transport, transformation and source data with the help of the law of the conservation of mass. Process models, evaluative models, models of real local, regional and global fate, as well as biological uptake models are presented and references to numerous examples are provided. An attempt is made to forecast future directions in the field of POPs modelling. It is expected that modelling techniques that do not rely on quantitative emission estimates as well as approaches that take into account spatial, temporal and climatic variability as well as parameter uncertainty will increase in importance. Finally, the relationship between modelling POPs and models of other pollutant issues is addressed, as are potential interactions between POPs and pollutant issues such as eutrophication, acidification and global climate change.     

Graduated driver licensing: the New Zealand experience

In New Zealand, on 1 August 1987, a three-stage graduated driver licensing (GDL) system that applied to all new drivers aged 15-24 years was introduced. The essential elements of GDL were a 6-month learner license (supervised driving) and an 18-month restricted license stage (with restrictions on night driving and carrying passengers). A blood alcohol limit of 0.03 mg% applied at both stages. EVALUATION STUDIES: Early studies indicated that young people were reasonably accepting of the restrictions, with the passenger restriction being the least acceptable. Problems of compliance with the restricted license driving restrictions were reported. Evaluations of the impact of the graduated driver licensing (GDL) on serious traffic-related injury showed that up until 1991-1992, an 8% reduction could be attributed to GDL. At this time, it was considered that reduced exposure was the main reason for this reduction. However, the number of fatalities and hospital admissions among young people continued to decline, as did the population rate and the rate per number of licensed drivers among the young driver age group. A further evaluation study showed that drivers with a restricted license had a smaller proportion of crashes at night, and with passengers, compared with drivers licensed before GDL. IMPACT OF GDL: These results suggested that GDL restrictions had contributed to the reduction in crashes among young people and that it was not simply a case of reduced exposure to risk. An update of the most recent crash statistics indicated that, compared with older age groups, the fatal and serious injury crash rate among young people has remained substantially below the pre-GDL level. This suggests that the impact of GDL has not diminished over time.     

轰燃后火焰的辐射热通量计算

轰燃后火焰的热辐射危害，是目前确定建筑物间安全距离的主要依据之一。该文提出了轰燃后火焰在室外一定距离处辐射热通量的计算方法；并在喷出火焰不受室外风影响的情况下，利用小规模试验的结果对这一方法进行了验证。     

Tolerance (PICT) of the bacterial communities to copper in vineyards soils from Spain

To detect effects of Cu pollution, the Cu tolerance of soil bacterial communities extracted from several vineyards located in NW Spain was measured. Bacterial community tolerance was estimated by means of the thymidine (TdR) and leucine (Leu) incorporation techniques using either IC(50) values (the log of the metal concentration that reduced incorporation to 50%) or the percentage of activity at one specific Cu concentration (10(-6) mol L(-1)). The tolerance measurements by the TdR incorporation technique were similar to those obtained by the Leu incorporation method, indicating that the two methods were equivalent in terms of suitability for detecting the toxicity of Cu to soil bacterial communities. The two tolerance indices considered (IC50 values and percentage of activity) were closely correlated (r = 0.975, P < 0.001), showing that both were equally good in measuring Cu tolerance of the bacterial community. An increased bacterial community tolerance to Cu, indicating a pollution effect, was observed in vineyard soils with more than 100 mg Cu kg(-1) soil. Thus, the long-term use of Cu in vineyards has a toxic effect on the soil bacterial community, resulting in an increased tolerance. An effect of increased levels of Cu could not be detected when measuring bacterial community activity, pointing to the increased sensitivity to detect toxicity in field studies using tolerance measurements.     

Dissolved organic carbon in runoff and tile-drain water under corn and forage fertilized with hog manure

Dissolved organic carbon (DOC) export from soils can play a significant role in soil C cycling and in nutrient and pollutant transport. However, information about DOC losses from agricultural soils as influenced by management practices is scarce. We compared the effects of mineral fertilizer (MF) and liquid hog manure (LHM) applications on the concentration and molecular size of DOC released in runoff and tile-drain water under corn (Zea mays L.) and forage cropping systems. Runoff and tile-drain water samples were collected during a 2-mo period (October to December 1998) and DOC concentration was measured. Characterization of DOC was performed by tangential ultrafiltration with nominal cut-offs at 3 and 100 kDa. Mean concentration of DOC in runoff water (12.7 mg DOC L(-1)) was higher than in tile-drain water (6.5 mg DOC L(-1)). Incorporation of corn residues increased the DOC concentration by 6- to 17-fold in surface runoff, but this effect was short-lived. In runoff water, the relative size of the DOC molecules increased when corn residues and LHM were applied probably due to partial microbial breakdown of these organic materials and to a faster decomposition or preferential adsorption of the small molecules. The DOC concentration in tile-drain water was slightly higher under forage (7.5 mg DOC L(-1)) than under corn (5.4 mg DOC L(-1)) even though the application rates of LHM were higher in corn plots. We suggest that preferential flow facilitated the migration of DOC to tile drains in forage plots. In conclusion, incorporation of corn residues and LHM increased the concentration of DOC and the relative size of the molecules in surface runoff water, whereas DOC in tile-drain water was mostly influenced by the cropping system with relatively more DOC and larger molecules under forage than corn.     

Identifying fecal sources in a selected catchment reach using multiple source-tracking tools

Given known limitations of current microbial source-tracking (MST) tools, emphasis on small, simple study areas may enhance interpretations of fecal contamination sources in streams. In this study, three MST tools-Escherichia coli repetitive element polymerase chain reaction (rep-PCR), coliphage typing, and Bacteroidales 16S rDNA host-associated markers-were evaluated in a selected reach of Plum Creek in south-central Nebraska. Water-quality samples were collected from six sites. One reach was selected for MST evaluation based on observed patterns of E. coli contamination. Despite high E. coli concentrations, coliphages were detected only once among water samples, precluding their use as a MST tool in this setting. Rep-PCR classification of E. coli isolates from both water and sediment samples supported the hypothesis that cattle and wildlife were dominant sources of fecal contamination, with minor contributions by horses and humans. Conversely, neither ruminant nor human sources were detected by Bacteroidales markers in most water samples. In bed sediment, ruminant- and human-associated Bacteroidales markers were detected throughout the interval from 0 to 0.3 m, with detections independent of E. coli concentrations in the sediment. Although results by E. coli-based and Bacteroidales-based MST methods led to similar interpretations, detection of Bacteroidales markers in sediment more commonly than in water indicates that different tools to track fecal contamination (in this case, tools based on Bacteroidales DNA and E. coli isolates) may have varying relevance to the more specific goal of tracking the sources of E. coli in watersheds. This is the first report of simultaneous, toolbox approach application of a library-based and marker-based MST analyses to flowing surface water.     

Ecotoxic effect of phenanthrene on nitrifying bacteria in soils of different properties

Information on ecotoxicity of organic contaminants, such as polycyclic aromatic hydrocarbons (PAHs), in terrestrial environment is needed for establishing soil quality criteria and for risk assessment purposes. An ecotoxic effect of a model PAH compound (phenanthrene) toward soils microorganisms (nitrifying bacteria) was evaluated in 50 different soils. The soil samples were collected from agricultural land in four regions of Poland with varying levels of industrialization (Slaskie, Dolnoslaskie, Podlaskie, and Lubelskie voievodeships). Soils were characterized for basic physicochemical properties (texture, organic matter content, pH(KCl), total nitrogen content, total sorption capacity) and the content of contaminants including PAHs (73-800 microg kg(-1)), Pb (6-720 mg kg(-1)), and Zn (9-667 mg kg(-1)). Ecotoxicity of phenanthrene (applied at 10, 100, 500, and 1000 mg kg(-1)) to soils microorganisms was evaluated in laboratory studies in control conditions (incubation of soils for 7 d at 20 +/- 2 degrees C). Nitrification potential was used as the ecotoxicity measurements end point. The EC50 values (146-1670 mg kg(-1)) calculated from the square root-X linear regression model differed significantly in various soils, although it was difficult to establish a causative relationship between soil physicochemical characteristic and phenanthrene toxicity. A significant factor in the assessment of soils vulnerability to the effect of phenanthrene was level of soil contamination, particularly with PAHs. Soils with previous contamination were more susceptible (mean EC50, 325 mg kg(-1)) than soils from uncontaminated, rural areas (mean EC50, 603 mg kg(-1)).