Spatial and annual variability in concentrations and sources of Escherichia coli in multiple watersheds

Nonpoint source fecal contamination is a concern for drinking water supplies worldwide. In this study, 4812 E. coli isolates were classified to source. Results of this experiment show that the fecal coliform (FC) counts varied by year, month, and site, for each of the watersheds sampled. For both years, the lowest FC counts tended to be at the highest elevation sites followed by the drinking water intake sites at the lowest elevation. The highest FC counts tended to be at the mid-elevation sites on BX, Deer, and Duteau Creeks. The sources of E. coli varied significantly with stream for 2003 and 2004 (P < 0.001, df = 39), although the main sources of E. coli (avian, deer/elk, canine, rodent, bovine, and bear) tended to be similar between watersheds. The dominant sources of E. coli changed from 2003 (avian, deer/elk, and canine) to 2004 (avian, bovine, and rodent). It is important to look at the results of more than 1 year of source tracking data to get a better picture of the dominant sources within a watershed. Overall, wildlife was the largest contributor of E. coli to the watersheds in both 2003 (> 84%) and 2004 (> 73%).     

中西结合江南情

水晶牛肉 主料:酱牛健肉、青豆瓣、枸杞、肉皮. 调料:盐、味精、料酒. 做法:1、将牛健肉切成小丁,青豆飞水冲凉,肉皮飞水后把油脂去净切丝.     

Effect of NOx on secondary organic aerosol concentrations

The secondary organic aerosol (SOA) module in PMCAMx, a three-dimensional chemical transport model, has been updated to incorporate NOx-dependent SOA yields. Under low-NOx conditions, the RO2 radicals react with other peroxy radicals to form a distribution of products with lower volatilities, resulting in higher SOA yields. At high-NOx conditions, the SOA yields are lower because aldehydes, ketones, and nitrates dominate the product distribution. Based on recent laboratory smog chamber experiments, high-NOx SOA parametrizations were created using the volatility basis-set approach.The organic aerosol (OA) concentrations in the Eastern US are simulated for a summer episode, and are compared to the available ambient measurements. Changes in NOx levels result in changes of both the oxidants (ozone, OH radical, etc.) and the SOA yields during the oxidation of the corresponding organic vapors. The NOx dependent SOA parametrization predicts a maximum average SOA concentration of 5.2 microg m(-3) and a domain average concentration of 0.6 microg m(-3). As the NOx emissions are reduced by 25%, the domain average SOA concentration does not significantly change, but the response is quite variable spatially. However, the predicted average SOA concentrations increase in northern US cities by around 3% but decrease in the rural southeast US by approximately 5%. A decrease of the average biogenic SOA by roughly 0.5 microg m(-3) is predicted for the southeast US for a 50% reduction in NOx emissions.     

Estimated effects of composition on secondary organic aerosol mass concentrations

The composition dependence of secondary organic aerosol (SOA) mass concentrations is explored using an absorptive partitioning model under a variety of simplified atmospheric conditions. A thermodynamic model based on the Wilson equation is used to estimate activity coefficients for mixtures containing primary organics, secondary organics, and water. Changes in the mean molecular weight of the absorbing aerosol mixture due to the presence of water are also accounted for. Model simulations use semivolatile and primary organic components with differing affinities for each other and for water. Results suggest that aerosol composition has an effect on SOA levels that is significant and comparable in magnitude to those due to diurnal temperature variations and semivolatile precursor emission rates. For dissimilar organic components at zero relative humidity, predicted peak SOA mass concentrations are reduced up to 45%. Under low and high relative humidity conditions, SOA levels increase by 3-41% and 11-130%, respectively, depending on the hydrophobicity of the organic components, with maximum concentrations at night when humidity is highest Effects are most pronounced for relatively volatile components that are most sensitive to shifts in the amount and type of absorbing aerosol.     

Enterococci concentrations in diverse coastal environments exhibit extreme variability

Fecal indicator bacteria (FIB) concentrations in a single grab sample of water are used to notify the public about the safety of swimming in coastal waters. If concentrations are over a single-sample standard, waters are closed or placed under an advisory. Previous work has shown that notification errors occur often because FIB vary more quickly than monitoring results can be obtained (typically 24 h). Rapid detection technologies (such as quantitative polymerase chain reaction) that allow FIB quantification in hours have been suggested as a solution to notification errors. In the present study, I explore variability of enterococci (ENT) over time scales less than a day that might affect interpretation of FIB concentrations from a single grab sample, even if obtained rapidly. Five new data sets of ENT collected at 10 and 1 min periodicities for 24 and 1 h, respectively, are presented. Data sets are collected in diverse marine environments from a turbulent surf zone to a quiescent bay. ENT vary with solar and tidal cycles, as has been observed in previous studies. Over short time scales, ENT are extremely variable in each environment even the quiescent bay. Changes in ENT concentrations between consecutive samples (1 or 10 min apart) greater than the single-sample standard (104 most probable number per 100 mL) are not unusual. Variability, defined as the change in concentration between consecutive samples, is not distinct between environments. ENT change by 60% on average between consecutive samples, and by as much as 700%. Spectral analyses reveal no spectral peaks, but power-law decline of spectral density with frequency. Power-law exponents are close to 1 suggesting ENT time series share properties with 1/f noise and are fractal in nature. Since fractal time series have no characteristic time scale associated with them, it is not obvious how the fractal nature of ENT can be exploited for adaptive sampling or management. Policy makers, as well as scientists designing field campaigns for microbial source tracking and epidemiology studies, are cautioned that a single sample of water reveals little about the true water quality at a beach. Multiple samples must be taken to gain a snapshot into the patchy structure of microbial water quality and associated human health risk.     

Source contributions of sulfate aerosol over East Asia estimated by CMAQ-DDM

We applied the decoupled direct method (DDM), a sensitivity analysis technique for computing sensitivities accurately and efficiently, to determine the source-receptor relationships of anthropogenic SO(2) emissions to sulfate aerosol over East Asia. We assessed source contributions from East Asia being transported to Oki Island downwind from China and Korea during two air pollution episodes that occurred in July 2005. The contribution from China, particularly that from central eastern China (CEC), was found to dominate the sulfate aerosols. To study these contributions in more detail, CEC was divided into three regions, and the contributions from each region were examined. Source contributions exhibited both temporal and vertical variability, largely due to transport patterns imposed by the Asian summer monsoon. Our results are consistent with backward trajectory analyses. We found that anthropogenic SO(2) emissions from China produce significant quantities of summertime sulfate aerosols downwind of source areas. We used a parametric scaling method for estimating anthropogenic SO(2) emissions in China. Using column amounts of SO(2) derived from satellite data, and relationships between the column amounts of SO(2) and anthropogenic emissions, 2009 emissions were diagnosed. The results showed that 2009 emissions of SO(2) from China were equivalent to 2004 levels.     

古韵今风 中西合璧——行之行的家居陈设艺术

<正>在家居设计中,古典与现代、中式与西式的装饰风格,如何使之相得益彰,迥异的风格于融合之中获得协调,异域情调于错位中凸现艺术品位,总是耐人寻味。北京行之行家具有限公司融汇多年来对中式传统家具市场的认识和经验,结合现代人对中式家具的新思想和新需求,推陈出新,行之行的中国风家居艺术馆的设计师们通过一些风格混搭的有益尝试,为我们展示了这个充满挑战而又创意无限的领域。     

二十世纪初东、西文化交流下的中国玉器(之二)

西方文艺复兴运动兴起以后,美学的理论经由西方传教士的东来,渐渐影响我国雕塑艺术品。19世纪中期是西方美学中现实主义美术兴起后,经过淬炼达到最蓬勃兴旺的时期,他们讲究的透视、比例,以及光线明暗的表达出现在我国艺术品上了。同时二十世纪初期,装饰艺术设计运动应运而生,诸如卡地亚等品牌的珠宝设计加入中国风的彩色趣味,成为经典作品。     

缓坡植烟田土壤微量元素的空间变异特征

采用地统计学和地理信息系统(GIS)相结合的方法,对典型缓坡植烟田土壤有效微量元素含量的空间变异规律进行研究,并运用普通克里格(Kriging)进行最优无偏线性估计,绘制空间分布图。结果表明,研究区域4种微量元素含量均属于中等程度变异,变异性大小表现为Zn>Mn>Fe>Cu。土壤Fe和Zn的最适模型为指数模型;Mn和Cu为球状模型。土壤Cu和Zn块金系数分别为20%、23.7%,具有强烈的空间相关性;Fe和Mn为28%和43.5%,具有中等程度的空间相关性。各向异性分析表明,土壤Cu存在较强烈的各向异性,Mn的各向异性则较小。研究区4种土壤元素含量的低值均出现在坡度大的中北部,东北部较平缓的区域含量则较高;同一坡向下,坡度是影响微量元素含量空间分布的重要地形因素。因此,在山地烟田精准施肥决策中应考虑坡度等地形因素对微量元素空间变异的影响。     

Causes of variability in pesticide and PCB concentrations in air near the Great Lakes

Data through 2001 from the Integrated Atmospheric Deposition Network (IADN) were used to investigate the causes of variability in gas-phase polychlorinated biphenyl (PCB) and pesticide concentrations measured near Lakes Michigan, Erie, and Superior. A multiple linear regression model that incorporates temperature and time was used explain the variability in the concentrations. Our approach used autocorrelation analyses of the residuals to help us determine the effectiveness of the regression. Autocorrelation plots forthe in-use pesticide lindane indicated that an agricultural application cycle was also present in the regression residual data at all sites. The addition of parameters for this effect to the regression equation accounted for, on average, 16% more of the variability in the data. Similar analyses forthe in-use pesticide endosulfan did not show an agricultural application effect. The banned compounds DDT and chlordane showed that temperature and time correctly accounted for the variability in the atmospheric concentrations of these compounds at all sites. In contrast to the other compounds, PCBs and hexachlorobenzene showed strong residual autocorrelation patterns near Lake Michigan of an unknown origin.     

On-line analysis of urban particulate matter focusing on elevated wintertime aerosol concentrations

A 10-day winter sampling campaign was conducted in downtown Toronto for particulate matter (PM) air pollution in the fine (<2.5 microm) size range. An aerosol laser ablation mass spectrometer (LAMS), a tapered-element oscillating microbalance (TEOM), and an aerodynamic particle sizer (APS) were operated in parallel to characterize the PM on-line. In this study, the LAMS observed differences in the chemical composition between three separate episodes with higher PM2.5 mass and APS counts. LAMS results showed that in one instance of elevated PM, organic amines were present in the particulates. Temporal analyses of this episode revealed chemical transformations as the amines, characterized by m/z peaks 58(C3HeN)+, 86(C5H2N)+, and nitrates, increased in number concentration while Ca and hydrocarbon particle classes concurrently decreased. On another day, sulfates were found to have increased significantly. The third event was only 4 h in duration and exhibited an increase in the number of submicron-sized K/hydrocarbons and sulfate-containing particles. In this last event, the hydrocarbons and a K to Fe ratio enrichment indicated there was likely a contribution from a combustion source. This work offers some of the first insights into single particle size and chemistry in a cold winter climate.     

Causes of variability in concentrations of polychlorinated biphenyls and polybrominated diphenyl ethers in indoor air

Airborne concentrations of PCBs and PBDEs were measured in offices, homes, public environments, and cars. Variations in concentrations between different rooms in the same domestic and office buildings, showed some intra-building variability for both compound groups. Stepwise multiple linear regression analysis revealed no clear and consistent relationships between log-normalized concentrations of PCBs and PBDEs in homes and offices and factors such as the number of personal computers. This is considered to reflect the complexity of relationships between indoor air contamination and microenvironment characteristics. The influence of personal computers was demonstrated when PBDE concentrations in one office fell appreciably following the exchange of a computer constructed in 1998 for one dating from 2003. Concentrations of PCBs in buildings constructed between 1950 and 1979 were significantly higher (p < 0.001) than in those constructed since. When two of the most contaminated cars were omitted as outliers, a significant (p < 0.01) positive linear relationship was detected between PBDE concentrations and vehicle age. Concentrations of PCBs and PBDEs were monitored throughout a calendar year in four homes and four offices. Although concentrations in warmer months usually exceeded those in colder months, seasonal variability in indoor contamination appears less significant than observed previously for outdoor air.     

Spatial and temporal variability of arsenic solid-state speciation in historically lead arsenate contaminated soils

The arsenic (As) solid-state speciation (i.e., oxidation state, precipitates, and adsorption complexes) is one of the most important factors controlling dissolved As concentrations at As contaminated sites. In this case study, two representative subsurface samples (i.e., oxidized and semi-reduced sites) from former lead arsenate contaminated soils in the northeastern United States were chosen to investigate the effects of aging on As retention mechanisms using multiscale spectroscopic techniques. X-ray powder diffraction (XRD), synchrotron based microfocused (micro) XRD, in situ micro-synchrotron based X-ray fluorescence spectroscopy (SXRF), and micro-X-ray absorption near edge structure (XANES) spectroscopy were used to compliment the final bulk X-ray absorption spectroscopy (XAS) analyses. In the sample from an oxic area, As is predominantly (approximately 71%) present as As(V) adsorbed onto amorphous iron oxyhydroxides with a residue (approximately 29%) of an original contaminant, schultenite (PbHAsO4). Contrarily, there is no trace of schultenite in the sample from a semi-reduced area. Approximately 25% of the total As is present as adsorbed phases on amorphous iron oxyhydroxide and amorphous orpiment (As2S3). The rest of the fractions (approximately 46%) were identified as As(V)-Ca coprecipitates. This study shows that aging effects can significantly alter the original chemical constituent (schultenite) in soils, resulting in multi and site-specific As solid-state speciation. The variability in spatial and temporal scale may be important in assessing the environmental risk and in developing in situ remediation technologies.     

Predicted secondary organic aerosol concentrations from the oxidation of isoprene in the eastern United States

Isoprene, the most abundant non-methane hydrocarbon emitted into the troposphere, has generally not been considered a major source of SOA due to the relatively high volatility of its oxidation products. In this study, the SOA formed from the oxidation of isoprene is predicted using a three-dimensional chemical transport model, PMCAMx, across the eastern U.S. for July, October, January, and April 2001-2002. The variability of the measured SOA yields in the available smog chamber studies is captured by combining the base case scenario with upper and lower bound estimates of the measurements. For the base case simulation, the predicted annual average isoprene SOA concentration in the southeast is 0.09 microg m(-3) (bounds 0.04-0.23 microg m(-3)). Isoprene is predicted to produce 70% less SOA across the entire domain for spring and fall than during the summer and negligible amounts of SOA during the winter. During the summer, the average concentrations in the northeast are predicted to be 0.11 microg m(-3) (bounds 0.04-0.31 microg m(-3)) and in the southeast 0.19 microg m(-3) (bounds 0.11 -0.58 microg m(-3)). PMCAMx predictions are compared to available measurements of some isoprene SOA components in North Carolina and New York State. These modeling results suggest that on an annual basis isoprene oxidation is a small but non-negligible organic aerosol source in the eastern U.S. Its contribution is relatively more important during the summer and in the southeast U.S.     

东西方文化差异对家具设计的影响

东西方文化是两个不同的文化体系,存在着差异。而家具文化是文化的一个重要组成部分,文化的差异性造成了家具设计文化的差异性,也造成了东西方家具设计的差异性和家具设计的多样性。