生活污水处理厂污泥处置技术研究

针对生活污水处理厂污泥处置技术,介绍了国内外污泥的处理现状,提出了传统的污泥处置技术,主要是海洋倾倒,污泥消化技术法,污泥堆肥技术法,污泥的土地利用和污泥的有效利用法,给出林地利用与绿化利用随着污泥量的增长,污泥的处置越来越来受到人们的关注。介绍了国内外污泥处理现状和传统污泥处理处置方法,分析了污泥稳定和资源化处置技术及应用进展,提出了污泥堆肥和堆肥后污泥的土地利用是符合中国国情的污泥处置与资源化利用途径。     

旱季不同土地利用类型下岩溶碳汇效应差异

为研究不同土地利用类型下碳酸盐岩溶蚀对土壤CO2消耗量的差异,在2013年11月至2014年5月选取了柏树湾泉、兰花沟泉和后沟泉这3个岩溶泉进行水化学分析及野外监测.结果表明,在上覆植被为林地的柏树湾泉域,泉水的HCO-3浓度最高,草地与耕地下的兰花沟泉次之,耕地为主的后沟泉最低.柏树湾泉的HCO-3主要来自于碳酸对碳酸盐岩的溶蚀,Ca2++Mg2+与HCO-3的摩尔比接近0.5,而兰花沟泉和后沟泉的HCO-3则主要来源于硫酸和硝酸对碳酸盐岩的溶蚀,Ca2++Mg2+与HCO-3的摩尔比远远大于0.5.柏树湾泉域由于凋落物的输入以及土壤透气性差,土壤CO2更容易溶于下渗水并与碳酸盐岩反应,而兰花沟泉和后沟泉的耕地由于土壤疏松,土壤CO2更容易以土壤呼吸的形式返回到大气中.因此,为准确评估岩溶碳汇作用,需要研究不同土地利用类型下碳酸盐岩对CO2消耗量的差异.     

Spatial and Seasonal Response of Municipal Water Use to Weather across the Contiguous U.S.

Weather variability has the potential to influence municipal water use, particularly in dry regions such as the western United States (U.S.). Outdoor water use can account for more than half of annual household water use and may be particularly responsive to weather, but little is known about how the expected magnitude of these responses varies across the U.S. This nationwide study identified the response of municipal water use to monthly weather (i.e., temperature, precipitation, evapotranspiration [ET]) using monthly water deliveries for 229 cities in the contiguous U.S. Using city‐specific multiple regression and region‐specific models with city fixed effects, we investigated what portion of the variability in municipal water use was explained by weather across cities, and also estimated responses to weather across seasons and climate regions. Our findings indicated municipal water use was generally well‐explained by weather, with median adjusted R² ranging from 63% to 95% across climate regions. Weather was more predictive of water use in dry climates compared to wet, and temperature had more explanatory power than precipitation or ET. In response to a 1°C increase in monthly maximum temperature, municipal water use was shown to increase by 3.2% and 3.9% in dry cities in winter and summer, respectively, with smaller changes in wet cities. Quantifying these responses allows urban water managers to plan for weather‐driven variability in water use.     

Fatal pedestrian crashes on interstates and other freeways in the United States

Introduction: More than 800 pedestrians die annually in crashes on interstates and other freeways in the United States, but few studies have examined their characteristics. Method: Data from the Fatality Analysis Reporting System on pedestrians fatally injured during 2015–2017 were analyzed. Chi-square tests compared characteristics of pedestrians killed on interstates and other freeways with those that died on other roads, and across crash types among freeway deaths. Land use characteristics of locations where pedestrians were killed while crossing freeways in a large state (California) were identified using Google Earth. Results: A larger proportion of pedestrians killed on freeways died on dark and unlit roads (48% vs. 32%), were male (78% vs. 68%), or were ages 20–44 (55% vs. 32%) compared with pedestrians killed on other roads. Crossing (42%) was the most common crash type among pedestrian deaths on freeways, followed by disabled-vehicle-related crashes (18%). Pedestrians who died while crossing more often had blood alcohol concentrations ≥ 0.08 g/dL (40%) than those in disabled-vehicle-related (22%) or other crashes (34%). Deaths in crossing crashes were more likely than other freeway deaths to occur on urban roads (81%), at speed limits ≤50 mph (13%), or between 18:00 and 23:59 (49%), and 58% of crossing crashes analyzed for land use were located between residential and other (e.g., commercial, recreational) uses. Over a third (37%) of deaths in disabled-vehicle-related crashes occurred at speed limits ≥70 mph. Conclusions: A surprising proportion of pedestrian deaths occur on controlled-access roads not designed for walking. Countermeasures for these crashes need to be implemented to see meaningful reductions in pedestrian fatalities overall. Practical applications: Improving roadway and vehicle lighting, requiring reflective warning devices for marking disabled vehicles, constructing pedestrian overpasses and underpasses in areas frequently crossed, and promoting alternative means of traveling between residential and commercial areas could help.     

Can we gain precision by sampling with probabilities proportional to size in surveying recent landscape changes in the Netherlands?

Seventy-two squares of 100 ha were selected by stratified random sampling with probabilities proportional to size (pps) to survey landscape changes in the period 1996–2003. The area of the plots times the urbanization pressure was used as a size measure. The central question of this study is whether the sampling with probabilities proportional to size leads to gain in precision compared to equal probability sampling. On average 1.03 isolated buildings per 100 ha have been built, while 0.90 buildings per 100 ha have been removed, leading to a net change of 0.13 building per 100 ha. The area with unspoiled natural relief has been reduced by 2.3 ha per 100 ha, and the length of linear relicts by 137 m per 100 ha. On average 74 m of linear green elements have been planted per 100 ha, while 106 m have been removed, leading to a net change of −31 m per 100 ha. For the state variables ‘unspoiled natural relief', ‘ linear relicts', ‘removed linear green elements', and ‘new – removed linear green elements' there is a gain in precision due to the pps-sampling. For the remaining state variables there is no gain or even a loss of precision (`new buildings', ‘removed buildings', ‘new – removed buildings', ‘new linear green elements'). Therefore, if many state variables must be monitored or when interest is not only in the change but also in the current totals, we recommend to keep things simple, and to select plots with equal probability.     

Estimation of Land Use Specific Runoff and Pollutant Concentration for Tapi River Basin in India

Non-point source (NPS) pollution is the result of various land use practices such as agriculture, sites of construction and waste disposal, urban development and so on. The control of NPS pollution is possible by regular monitoring and assessment on watershed basis to educate people for implementing well-known structural and non-structural measures. Recent trend is to use GIS based modelling tool for assessment of rainfall-runoff and non-point loading. The approach requires generation and analysis of basin wide data on various features of land and estimates of Event Mean Concentrations (EMCs) of pollutants in the runoff. In the present paper, basin wide data in different districts of Tapi basin has been analysed for land use distribution; fertilizer application; low, medium and high-density habitation; and annual rainfall. Coefficients of runoff have been estimated considering pervious and impervious area for different land use types, and compared with the reported values for Indian conditions. The estimated mean annual runoff flow indicated that two districts Jalgaon and Dhule contribute maximum runoff to the Tapi River. Estimates of EMCs for BOD and nutrients (N and P) in the runoff from various districts are useful in GIS-based modelling study for NPS pollution assessment.     

土地利用/覆盖变化对长江上游非点源污染影响研究

在国内外相关研究的基础上,利用输出系数模型,结合RS和GIS技术,对长江上游的非点源污染负荷进行了空间模拟和负荷估算.模拟结果表明,在不考虑流域损失的前提下,由于土地利用造成的非点源污染负荷TN总量从20世纪70年代的123万t下降至2000年的116万t,基本呈逐年减少的趋势,由土地利用造成的TP的变化趋势与TN基本相同,从70年代的3.7万t下降到2000年的3.5万t左右.就省份、土地利用类型和水系而言,四川省、种植用地和草地以及金沙江水系和嘉陵江水系对长江上游的非点源污染贡献较大.在非点源污染负荷强度上,重庆市和嘉陵江水系单位面积负荷最高,是今后应重点治理的地区.结果表明,该模型可以对长江上游这样的超大尺度空间的非点源污染进行较好的空间模拟.     

经济快速增长区土地利用变化对土壤质量影响研究

以苏锡常地区具有典型性的原锡山市不同土地利用类型和不同时间的土壤取样点为研究对象,从时空转换角度分析土地利用变化对土壤质量的影响. 结果表明,1980—1995年,苏锡常地区土地利用结构变动速率为0.59;1995—2000年,苏锡常地区土地利用结构变动速率增加为0.74. 统计分析和独立样本t检验结果表明:1982—2005年原锡山市pH降低0.58,w(有机质)降低1.02 g/kg,w(全氮)降低0.16 g/kg,w(全磷)降低0.48 g/kg,w(速效氮)降低7.63 mg/kg,w(速效磷)增加26.16 mg/kg,w(速效钾)增加36.9 mg/kg,土壤含水率降低0.52%,土壤的相对质量指数降低3.06;在不同土地利用方式下,土壤质量各指标的变化具有明显的差异性.      

Modeling of air quality with a modified two-dimensional Eulerian model： A case study in the Pearl River Delta （PRD） region of China

A modified two-dimensional Eulerian air quality model was used to simulate both the gaseous and particulate pollutant concentrations during October 21-24, 2004 in the Pearl River Delta （PRD） region, China. The most significant improvement to the model is the added capability to predict the secondary organic aerosols （SOA） concentrations because of the inclusion of the SOA formation chemistry. The meteorological input data were prepared using the CALMET meteorological model. The concentrations of aerosol-bound species such as NO3^-, NH4^＋, SO4^2-, and SOA were calculated in the fine particle size range （〈2.5 μm）. The results of the two-dimensional model were compared to the measurements at the ground level during the PRD Intensive Monitoring Campaign （IMC）. Overall, there were good agreements between the measured and modeled concentrations of inorganic aerosol components and O3. Both the measured and the modeled results indicated that the maximum hourly O3 concentrations exceeded the China National Air Quality Standard. The predicted 24-h average SOA concentrations were in reasonable agreement with those predicted by the method of minimum OC/EC ratio.     

山地农业资源的时空性与持续利用研究：以陕西秦巴山地为例

山地是一种特殊的生态环境类型,受自然分异规律与人类经济活动的双重干预和影响,产生其特有的时空分异规律与层带组合格局。通过土地生态类型格局分析,可以揭示山地生态环境类型结构瑟功能的异质性和有序性,从而为探讨农业资源的时空性及其开发利用模式提供科学指导。