乌鲁木齐空气微生物含量的测定

用自然平皿沉降法对乌鲁木齐市13个室内外空气测点作了微生物含量的测定,结果表明平均室外空气的细菌、真菌、总菌含量及F/T%分别为28583 8、780 5、29364 3CFU·m-3及2 7,证实了该市空气处于中度微生物污染状态。少量测点显示其空气已受到严重污染,空气质量不佳。室内空气微生物污染也重。空气微生物污染以细菌为主。分析了室外空气微生物含量的时空分布特点差异,探讨了其成因,并与其他城市作了比较。文章指出增强环境忧患意识,采用切实而有效措施,减少环境污染的必要性。     

对高校扩招有关问题的思考

高等院校扩大招生,满足了广大群众迫切希望接受高等教育的愿望,满足了社会对各种高级专门人才日益增长的需求。伴随着连续的扩招,在高教界普遍出现了基础设施不足,教育质量受到影响的现象,本文针对这一问题进行分析与探讨,并提出了改进的建议。     

Alteration in Rhizosphere Soil Properties of Afforested <Emphasis Type="Italic">Rhamnus lycioides</Emphasis> Seedlings in Short-Term Response to Mycorrhizal Inoculation with <Emphasis Type="Italic">Glomus intraradices</Emphasis> and Organic Amendment

The reestablisment of autochthonous plant species is an essential strategy for recovering degraded areas under semiarid conditions. A field experiment was carried out to assess the short-term effect of two reafforestation methods involving mycorrhizal inoculation and compost addition on soil quality parameters and Rhamnus lycioides seedling growth. The nutrient content (NPK) and enzymatic activities (dehydrogenase, urease, protease-BAA, acid phosphatase and β-glucosidase) increased and bulk density decreased in the rhizosphere soil with the organic amendment. Biomass C of rhizosphere soil increased by at least 240% with respect to the control soil after mycorrhizal inoculation and the combination of compost addition + mycorrhizal inoculation. Both mycorrhizal inoculation and composted organic residue addition increased R. lycioides seedling growth in the same proportion. In the short term, we conclude that the application of both reafforestation methods not only enhances the establishment of R. lycioides seedlings, but also improves soil quality.     

Societal Concerns about Pork and Pork Production and Their Relationships to the Production System

Pork producers in Western Europe moreand more encounter a variety of societalconcerns about pork and pork production. Sofar, however, producers predominantly focusedon low consumer prices, therewith addressingjust one concern. This resulted in an intensiveand large-scale production system, decreasinglyrelated to the area of farm land, andaccompanied with increasing concerns aboutsafety and healthiness of pork, animal welfare,environmental pollution, and others.An overview was given of possible concernsabout West-European pork production with theconsumers, citizens, and producers, and thoseconcerns are traced back to the pork productionsystem. The various kinds and qualities ofinformation about the pork production system onwhich possible concerns are based have beenworked out extensively in this paper. Knowledgeabout the aspects of pork production that cangive rise to concerns can be used in two ways.First, the communication about those aspectstowards consumers and citizens can be adjustedor extended to give them better possibilitiesto make food choices or to develop their ownopinions about pork production. Second,producers could change the pork productionsystem such that it better satisfies consumersand citizens. Such adaptations are wellpossible, as three pork quality schemes, whichhave been evaluated, illustrate. However, mostof these adaptations can only be carried out atthe cost of the present low consumer prices andwill not occur spontaneously on a large scale.Therefore, accounting for the type andrelevance of the concerns, legislation isnecessary to address societal concerns in abalanced way such that pork production systemsbecome acceptable for the majority of oursociety.     

Past and future sustainability of water policies in Europe

The article contributes to a discussion on two global issues on water: water resources management, and water supply and sanitation. Focusing on Europe, it traces the legal roots of current systems in history: as a resource, water is considered as a common property, rather than a market good; while as a public service it is usually a commodity. Public water supply and sanitation technologies and engineering have developed under three main paradigms: quantitative and civil engineering; qualitative and chemical/sanitary engineering (both on the supply side); and the most recent one, environmental engineering and integrated management (on the demand side). The cost of public drinking water is due to rise sharply in view of the two‐fold financial challenge of replacing an ageing infrastructure and keeping up with ever‐rising environmental and sanitary quality standards. Who will pay? Government subsidies, or water users? The author suggests that apparent successes with privatisation may have relied heavily on hidden government subsidies and/or the healthy state of previously installed water infrastructure: past government subsidies are still felt for as long as the lifetime of the infrastructure. The article stresses the importance of public participation and decentralized local management of water and sanitation services. Informing and involving users in water management decisions is seen as an integral part of the ‘ethics’ side of the crucial three E's (economics, environment, ethics). The article strongly argues for municipal provision of water services, and hopes that lessons learnt and solutions found in the European experience may serve water services management efforts in other regions of the world.     

水危机与生态环境保护

本文对水危机及全球水源状况进行了分析，为保护人类水资源与生态环境进行了有益的探索。     

NUTRIENT LOADING ASSESSMENT IN THE ILLINOIS RIVER USING A SYNTHETIC APPROACH1

ABSTRACT: A synthetic relationship is developed between nutrient concentrations and discharge rates at two river gauging sites in the Illinois River Basin. Analysis is performed on data collected by the U.S. Geological Survey (USGS) on nutrients in 1990 through 1997 and 1999 and on discharge rates in 1988 through 1997 and 1999. The Illinois River Basin is in western Arkansas and northeastern Oklahoma and is designated as an Oklahoma Scenic River. Consistently high nutrient concentrations in the river and receiving water bodies conflict with recreational water use, leading to intense stakeholder debate on how best to manage water quality. Results show that the majority of annual phosphorus (P) loading is transported by direct runoff, with high concentrations transported by high discharge rates and low concentrations by low discharge rates. A synthetic relationship is derived and used to generate daily phosphorus concentrations, laying the foundation for analysis of annual loading and evaluation of alternative management practices. Total nitrogen (N) concentration does not have as clear a relationship with discharge. Using a simple regression relationship, annual P loadings are estimated as having a root mean squared error (RMSE) of 39.8 t/yr and 31.9 t/yr and mean absolute percentage errors of 19 percent and 28 percent at Watts and Tahlequah, respectively. P is the limiting nutrient over the full range of discharges. Given that the majority of P is derived from Arkansas, management practices that control P would have the most benefit if applied on the Arkansas side of the border.     

A THEORETICAL TRAVEL TIME BASED ON WATERSHED HYPSOMETRY1

ABSTRACT: The time to hydrograph peak of a watershed basin has been found to correlate with various statistical attributes (e.g., skewness and kurtosis) of its hypsometric curve (treated as probability distribution). This paper presents a theoretical travel time that is conceptually analogous to the time to hydrograph peak and can be calculated directly from the hypsometric curve of a watershed basin based on gravity and acceleration. The theoretical travel times for 23 selected watersheds in the United States are found to correlate significantly with their corresponding hypsometric attributes. In addition, the theoretical travel times are consistent with the times of concentration estimated from the Federal Aviation Administration method. Thus, this paper offers a simple theoretical explanation to the empirically identified linkage between time to hydrograph peak and hypsometric attributes. This theoretical travel time can provide an alternative way of characterizing the effects of basin morphometry on hydrologic response.     

INCREASED BASEFLOW IN IOWA OVER THE SECOND HALF OF THE 20TH CENTURY1

ABSTRACT: Historical trends in annual discharge characteristics were evaluated for 11 gauging stations located throughout Iowa. Discharge records from nine eight‐digit hydrologic unit code (HUC‐8) watersheds were examined for the period 1940 to 2000, whereas data for two larger river systems (Cedar and Des Moines Rivers) were examined for a longer period of record (1903 to 2000). In nearly all watersheds evaluated, annual base flow, annual minimum flow, and the annual base flow percentage significantly increased over time. Some rivers also exhibited increasing trends in total annual discharge, whereas only the Maquoketa River had significantly decreased annual maximum flows. Regression of stream discharge versus precipitation indicated that more precipitation is being routed into streams as base flow than as storm flow in the second half of the 20th Century. Reasons for the observed stream flow trends are hypothesized to include improved conservation practices, greater artificial drainage, increasing row crop production, and channel incision. Each of these reasons is consistent with the observed trends, and all are likely responsible to some degree in most watersheds.     

INCORPORATING NATURAL VARIABILITY,UNCERTAINTY, AND RISK INTO WATER QUALITY EVALUATIONS USING DURATION CURVES1

ABSTRACT: Quantifying natural variability, uncertainty, and risk with minimal data is one of the greatest challenges facing those engaged in water quality evaluations, such as development of total maximum daily loads (TMDL), because of regulatory, natural, and analytical constraints. Quantification of uncertainty and variability in natural systems is illustrated using duration curves (DCs), plots that illustrate the percent of time that a particular flow rate (FDC), concentration (CDC), or load rate (LDC; “TMDL”) is exceeded, and are constructed using simple derived distributions. Duration curves require different construction methods and interpretations, depending on whether there is a statistically significant correlation between concentration (C) and flow (Q), and on the sign of the C‐Q regression slope (positive or negative). Flow DCs computed from annual runoff data vary compared with an FDC developed using all data. Percent exceedance for DCs can correspond to risk; however, DCs are not composed of independent quantities. Confidence intervals of data about a regression line can be used to develop confidence limits for the CDC and LDC. An alternate expression to a fixed TMDL is suggested as the risk of a load rate being exceeded and lying between confidence limits. Averages over partial ranges of DCs are also suggested as an alternative expression of TMDLs. DCs can be used to quantify watershed response in terms of changes in exceedances, concentrations, and load rates after implementation of best management practices.