为了可以深深深呼吸

时间已到初冬季节,除了御寒外,空气质量也变成了大家关心的问题。冬季,尤其是进入采暖季节之后,由于燃煤量增大,再加上每次冷空气过后,大气中出现逆温现象,污染物很难扩散,如果连续几天风力不大,污染物就像一层厚厚的被子盖在城市上空,让人感觉"暗无天日"。     

基于季节指数的四川省旅游季节性研究

旅游季节性波动是旅游经济学研究的重要命题。选取四川省旅游总收入作为分析指标,采用年度季节强度指数(R)与月季指数(Zt)揭示旅游总收入的年度季节集中性与月度季节变化规律。结果显示,R值整体上呈逐年递增的趋势,指标随季节变化明显,且按一定规律分布;Zt值指示3月、6月、8月、9月、10月、12月为旅游旺季,其余月份为淡季。研究结论为四川旅游经济的淡旺季问题提供了基础数据,也为进一步合理修订全国节日放假办法提供了重要的科学决策依据。     

变频空调器中国能效与美国能效标准计算差异分析

空调能效标准作为产品节能控制的有效手段,已普遍被各国采用。本文针对美国能效标准ARI Standard 210/240-2008~([1])与中国能效标准GB/T 7725-2004~([2])中的季节能效测试及计算方法的差异进行了解析,分析并实验验证了两种标准下的能效值差异,提出国标发展方向建议。通过验证,同一样机美标下得出的制冷季节能效SEER值始终高于国标。国标入门1级能效样品的SEER和HSPF分别高出美国能源之星要求的47.3 %、37.4 %,为国标与美标能效等级的横向对应关系提供参考。     

公路工程环境影响重大变动与变更环评要点分析

公路工程属易产生重大不良环境影响、易发生重大变动的建设项目，但由于重大变动判定标准不清晰、重新报批环评的时间节点不统一、变更环评文件形式和内容不规范等问题，导致环评违法违规现象频发，变更环评制度管理效能难以有效发挥。根据公路建设项目重大变动有关定义，结合环境影响评价技术导则、环境影响评价审批原则、公路建设项目工程特性，及调查和分析四川省公路建设项目环境影响重大变动重新报批情况，对公路建设项目环境影响重大变动环评要点进行归纳和总结，在一定程度上有利于环境影响评价制度的完善，可为公路建设项目重大变动环境影响评价文件的编制和审批提供思路。     

龙泉湖浮游植物群落分布及季节变化

2008年5月~2009年4月对龙泉湖的浮游植物群落结构进行了研究。结果表明:龙泉湖浮游植物共计8门,71属,225种(含变种和变型),种群结构主要以蓝藻、绿藻和硅藻为主。浮游植物种类组成季节变化显著,冬季、初春以硅藻为主,夏秋季以蓝藻为优势,并将优势从5月持续至10月。龙泉湖浮游植物数量变化在5.26×105个/L~636.77×105个/L之间,标志龙泉湖的水体营养程度较高。     

伪环保批判书：“反季节植树”之批判

自从塑料大棚解决了部分蔬菜的反季节生长问题之后,人们似乎产生了一个错觉,以为现代技术已经可以越过季节的限制而随心所欲。因之,好多事情便与季节拧着干,或者说人们似乎淡忘了自然界中还有四季的分别。本该在一个特定季节做的事情,人们偏偏放到其他季节去做。比如植树就是这样。近年来，一些城市植树绿化的时节已渐渐模糊，有些城市反季节植树的总数己占到植树总量的40％以上。植树节前后不植树，酷暑盛夏挥汗如雨猛植树的现象在许多城市都不鲜见。     

中国电器科学研究院标准化工作取得新突破——作为第一单位获得2008年中国标准创新贡

金秋十月，收获的季节。近日接国家质量监督检验检疫总局、国家标准化管理委员会文件《关于公布2008年“中国标准创新贡献奖”获奖项目的通知》（国质检标联【2009】426号），经中国标准化专家委员会评审和国家标准化管理委员会审核公示，全国共有124项标准获“中国标准创新贡献奖”，     

BOD5测定中以花园土浸出液作为接种液使用量季节差异探讨

通过对不同季节测定BOD5中以花园土浸出液为接种液使用量进行分析、探讨,旨在为今后更为精确、简便地测定BOD5提供科学的依据。     

烟台地区在业人口就业结构分析

根据人口普查资料，本文从行业和职业方面对烟台地区在业人口的就业结构现状及变动特点进行了系统分析，并在此基础上对农业剩余劳动力的转移问题作了深入探讨。     

我从山中来带着兰花草

这次出差路过大别山腹地一个国家级自然保护区,在这个季节,路边无论是高大的乔木还是低矮的灌木甚至是平时不为人所注意的野草,都尽量展示出生命中所具备的原始冲动,它们交织成一幅幅欣欣向荣的春山全景图,处处都张扬着春天的气息。     

四川省游客流时间分布特征及成因分析

将四川省作为旅游目的地,以旅游人数为指标,运用季节性强度指数、季节指数以及数理统计方法比较分析了四川省入境游客流与国内游客流的时间分布特征,主要从年际变化特征与月变化特征两个方面进行研究。依据四川省主要旅游景点季节性强度指数的时间变化特征,从旅游主体、旅游客体和旅游媒体三方面分别探讨了游客流时间变化的成因,重点研究了旅游客体类型、知名度、区位等因素对游客流时间分布特征的影响。     

SOME HYDROLOGIC IMPACTS OF PLOWING RANGELAND SOILS1

ABSTRACT: Rainfall simulator studies were conducted during 1982 and 1983 on agricultural and native rangeland soils of the same soil series in northern Utah. Results indicate that the same soil series mapped at different locations on agricultural land will have similar 10, 20, and 30 minute infiltration rates and similar interrill erosion rates. Seasonal differences in infiltration and erosion rates were significant. Comparisons between agricultural and native soils were complicated by three-way statistical interactions. Seasonal variations in both infiltration rates and erosion rates were greatest on agricultural soils. Of four soil series on native rangeland, only one showed significant seasonal variation in infiltration rates, while erosion rates were similar across all seasons for all soil series. Soil and cover factors important in predicting infiltration and erosion were identified.     

Modeling Variability and Trends in Pesticide Concentrations in Streams1

Abstract: A parametric regression model was developed for assessing the variability and long‐term trends in pesticide concentrations in streams. The dependent variable is the logarithm of pesticide concentration and the explanatory variables are a seasonal wave, which represents the seasonal variability of concentration in response to seasonal application rates; a streamflow anomaly, which is the deviation of concurrent daily streamflow from average conditions for the previous 30 days; and a trend, which represents long‐term (inter‐annual) changes in concentration. Application of the model to selected herbicides and insecticides in four diverse streams indicated the model is robust with respect to pesticide type, stream location, and the degree of censoring (proportion of nondetections). An automatic model fitting and selection procedure for the seasonal wave and trend components was found to perform well for the datasets analyzed. Artificial censoring scenarios were used in a Monte Carlo simulation analysis to show that the fitted trends were unbiased and the approximate p‐values were accurate for as few as 10 uncensored concentrations during a three‐year period, assuming a sampling frequency of 15 samples per year. Trend estimates for the full model were compared with a model without the streamflow anomaly and a model in which the seasonality was modeled using standard trigonometric functions, rather than seasonal application rates. Exclusion of the streamflow anomaly resulted in substantial increases in the mean‐squared error and decreases in power for detecting trends. Incorrectly modeling the seasonal structure of the concentration data resulted in substantial estimation bias and moderate increases in mean‐squared error and decreases in power.     

FEASIBILITY OF SEASONAL WATER PRICING CONSIDERING METERING COSTS1

ABSTRACT: Efficiency implications of seasonal pricing, uniform pricing, and optimal seasonal pricing with metering costs are analyzed qualitatively using classical optimization technique. The first two schemes are special cases of the last pricing scheme. A nonlinear-integer programming model is formulated for a case study application to Salt Lake City to examine the feasibility of seasonal pricing. The analysis indicates that uniform pricing is preferable unless metering costs are substantially lower than present levels.     

WATER QUALITY TRENDS AT INFLOWS TO EVERGLADES NATIONAL PARK1

ABSTRACT: Water quality data collected at inflows to Everglades National Park (ENP) are analyzed for trends using the seasonal Kendall test (Hirsch et al., 1982; Hirsch and Slack, 1984). The period of record is 1977–1989 for inflows to Shark River Slough and 1983–1989 for inflows to Taylor Slough and ENP's Coastal Basin. The analysis considers 20 water quality components, including nutrients, field measurements, inorganic species, and optical properties. Significant (p<0.10) increasing trends in total phosphorus concentration are indicated at eight out of nine stations examined. When the data are adjusted to account for variations in antecedent rainfall and water surface elevation, increasing trends are indicated at seven out of nine stations. Phosphorus trend magnitudes range from 4 percent/year to 21 percent/year Decreasing trends in the Total N/P ratio are detected at seven out of nine stations. N/P trend magnitudes range from -7 percent/year to -15 percent/year. Trends in water quality components other than nutrients are observed less frequently and are of less importance from a water-quality-management perspective. The apparent nutrient trends are not explained by variations in marsh water elevation, antecedent rainfall, flow, or season.     

FOREST HYDROLOGY AND EXTREME RAINFALL FREQUENCY1

Extreme rainfall frequency analysis provides one means to predict, within certain limits of probability, the average time interval between the recurrences of storms of a specified duration and magnitude. This in turn furnishes the forest hydrologist a valuable tool for engineering design and runoff and erosion forecast. A modification in the application of the annual maximum and annual exceedance series analysis described by V. T. Chow can, for special purposes, lead to an even more useful estimate of extreme events on a seasonal basis. This can be particularly important on small forested headwater watersheds where the runoff response to extreme rainfall may vary considerably with seasonal changes in canopy cover and soil moisture characteristics. Although the application of data covering a relatively short period of record has produced some inconsistencies among the frequency diagrams, under certain circumstances for short-term recurrence interval forecast and for non-critical application the analysis of extreme rainfall frequency from less than 20 years data seems justified.     

Reconstructed Stream Flow for the Salt and Verde Rivers From Tree-Ring Data1

ABSTRACT: The Salt and Verde Rivers of central Arizona provide the water supply for metropolitan Phoenix and a considerable acreage of irrigated agriculture. Rapid urbanization has caused concern over future water supply and aggravated flooding in the already flood-prone Salt River Valley. Tree-ring data were used as a proxy source to extend the annual and seasonal runoff records back to A.D. 1580 and thus to determine whether the period of record for annual discharge adequately represents the long term flow characteristics of the two rivers. Results show that several periods of extended low flow have occurred during the past 400 years, many of which were more severe then any comparable period since 1890. The low flow periods appear to have a recurrence interval of about 22 years. Also the gaged records contain an above average number of high seasonal and annual flows when compared to the entire 400 years. The reconstructions contain important implications for future water supply and flood potentials in the Salt River Valley.     

SAMPLING FREQUENCY SELECTION FOR REGULATORY WATER QUALITY MONITORING1

ABSTRACT: The selection of sampling frequencies in order to achieve reasonably small and uniform confidence interval widths about annual sample means or sample geometric means of water quality constituents is suggested as a rational approach to regulatory monitoring network design. Methods are presented for predicting confidence interval widths at specified sampling frequencies while considering both seasonal variation and serial correlation of the quality time series. Deterministic annual cycles are isolated and serial dependence structures of the autoregressive, moving average type are identified through time series analysis of historic water quality records. The methods are applied to records for five quality constituents from a nine-station network in Illinois. Confidence interval widths about annual geometric means are computed over a range of sampling frequencies appropriate in regulatory monitoring. Results are compared with those obtained when a less rigorous approach, ignoring seasonal variation and serial correlation, is used. For a monthly sampling frequency the error created by ignoring both seasonal variation and serial correlation is approximately 8 percent. Finally, a simpler technique for evaluating serial correlation effects based on the assumption of AR(1) type dependence is examined. It is suggested that values of the parameter p₁, in the AR(1) model should range from 0.75 to 0.90 for the constituents and region studied.     

WATER RESOURCE MANAGEMENT AND DROUGHT FORECASTS IN SOUTH CAROLINA1

ABSTRACT: Despite potential benefits for resource planning, community water systems managers have not used seasonal climate forecasts extensively. Obstacles to forecast use include a lack of awareness of their existence, distrust of their accuracy, perceived irrelevance to management decisions, and competition from other technological innovations. In this paper, ways in which seasonal forecasts might be extended to address more directly some concerns of South Carolina community water systems managers are explored. From May 1998 through August 2002, this group experienced drought conditions that threatened water quality and supply and required restrictions on water consumption. Methods for incorporating long lead forecasts with joint probabilities of monthly temperature and precipitation to produce drought forecasts are demonstrated. When tailored to specific places, such forecasts show the likelihood of exceeding drought thresholds that would trigger water use restrictions. The methods illustrate how long lead forecasts can be extended and customized into secondary products that address issues of greater relevance to water resource managers.     

WATER QUALITY OF AN INTENSWE AGRICULTURAL WATERSHED IN QUEBEC1

ABSTRACT: . Under a watershed based approach being examined by the Quebec Ministry of Agriculture to accelerate the adoption of conservation practices, a study on the impacts of agricultural practices on the St. Esprit watershed was initiated in the fall of 1993. The water quality of this 26 km² intensive agricultural watershed was studied over an 18 month period. Water samples taken at the outlet of the watershed were analyzed for nitrate, phosphate, suspended sediment, and atrazine. Water quality data were analyzed to establish seasonal trends in pollutant concentration and load in the watercourse. Spring snowmelt was identified as a significant period of pollutant material export. All pollutant materials displayed seasonal variability in the export process. Peak pollutant concentrations were associated with high flow events. Mean observed pollutant concentrations did not exceed drinking water quality standards.