ESTIMATION OF PRE- AND POST-DEVELOPMENT NONPOINT WATER QUALITY LOADINGS1

ABSTRACT: A simple procedure for estimating pre- and post-development water quality loadings from residential communities is discussed. The procedure deals with: (a) gathering basic water quality loading numbers observed by others at several watersheds with various land uses; (b) obtaining the breakdown of proposed land uses at various phases of the community development; and (c) estimating pre- and post-development water quality loading numbers by taking the weighted average of the basic loading numbers in terms of areal coverages of different land uses at various phases of development. Results of this simplified procedure have been verified indirectly by comparing them with the estimates derived independently through a more fundamental but time-consuming approach. The procedure was used to evaluate the anticipated water quality impact of two future residential communities in South Florida by analyzing four water quality parameters: Suspended Soils (SS), Total Nitrogen (TN), Total Phosphorus (TP), and Biochemical Oxygen Demand (BOD₅). Although computation of loading numbers with mixed land uses is not an exact science at the present time, the recommended approach appears to be the best available technique to analyze quantitatively the water quality-quantity-land use interactions.     

Rethinking receiver operating characteristic analysis applications in ecological niche modeling

The area under the curve (AUC) of the receiver operating characteristic (ROC) has become a dominant tool in evaluating the accuracy of models predicting distributions of species. ROC has the advantage of being threshold-independent, and as such does not require decisions regarding thresholds of what constitutes a prediction of presence versus a prediction of absence. However, we show that, comparing two ROCs, using the AUC systematically undervalues models that do not provide predictions across the entire spectrum of proportional areas in the study area. Current ROC approaches in ecological niche modeling applications are also inappropriate because the two error components are weighted equally. We recommend a modification of ROC that remedies these problems, using partial-area ROC approaches to provide a firmer foundation for evaluation of predictions from ecological niche models. A worked example demonstrates that models that are evaluated favorably by traditional ROC AUCs are not necessarily the best when niche modeling considerations are incorporated into the design of the test.     

武汉市城市化过程中的空气质量响应研究

以武汉市2000-2013年的城市化水平和空气质量状况数据为基础,运用主成分分析法和目标比率模型构建综合评价体系,并用多元回归模型进行检验,探究城市化过程中的空气环境质量响应特征.结果表明:1)2000年以来,武汉城市化进入稳增长的快速抬升阶段,空气污染综合指数总体变化平稳,2013年有变坏的趋势;2)不同类型的污染物对城市化水平具有不同的响应规律和影响程度,SO2为倒“U”型,表明随着城市发展,SO2浓度得到控制并呈下降趋势;NO2为“U”型,近9年来NO2浓度不减反增,对空气环境污染严重;而PM10及空气质量综合水平表现为倒“N”型特征,表明现阶段空间环境呈现污染加重的趋势;3)城市化快速扩张过程中的基础设施建设、建筑扬尘,汽车尾气排放、工业烟尘等是影响武汉空间环境质量的主要因素,需有针对性地加强城市空气环境管理.     

高寒条件下振弦式传感器在线测量尾矿坝浸润线的误差分析及对策

为减少和消除高寒条件下振弦式传感器在线测量浸润线的误差,通过理论分析和现场试验,对造成误差的因素及其影响情况进行了深入研究。结果表明,振弦式传感器产生测量误差的主要来源为设备安装深度的测量误差与尾矿水密度及重力加速度的取值误差,并提出了减少或消除误差的方法和工程技术措施,为高寒地区的浸润线在线精确测量提供了重要指导意义。     

对生态红线的研究——宁夏生态红线划定的问题和思考

为了贯彻国家的可持续发展战略,更有效地解决中国的环境危机以及更好地进行中国的生态文明建设,就必须建立底线思维.中央第十八届三中全会通过的《中共中央关于全面深化改革若干重大问题的决定》明确规定了要划定生态保护红线.通过对生态保护红线的相关文献和政策进行分析,提出生态红线的类型和划定的思考,结合生态红线落地问题,对宁夏生态红线划定中存在的问题进行思考,以期为全国生态红线划定和生态保护提供参考.     

多级A／O膜生物反应器污泥活性研究

采用一种新型的多级A／O膜生物反应器处理污水,对该工艺的污泥活性进行了研究。结果表明,VSS／SS在实验过程中呈较弱的下降趋势,多级A／O池曝气室污泥比硝化速率逐室下降,但各缺氧室污泥比反硝化速率基本一致;污泥释磷、聚磷过程在30 min和1 h内基本完成,反硝化聚磷试验表明污泥中存在DPB的富集,反硝化作用是反硝化细菌与DPB共同作用的结果。     

公路线源大气环境影响预测方法对比分析研究

文章通过从模式原理、范围和特点等方面对AERMOD大气预测模式与EIAA预测模式进行对比分析,以甘肃省天水段G310国道升级改造项目为例,分别采用AERMOD和EIAA两种模式对交通线源排放的特征污染因子CO在各环境空气敏感点的小时最大浓度进行预测,并对预测值与实测值进行对比分析,探讨两种模式在公路线源大气环境影响预测中的适用性及差异性。以期为今后开展道路交通类建设项目大气环境影响预测评价中模式的选取提供参考和借鉴。     

基于能值分析的武穴市耕地利用效益时空特征分析

开展耕地利用效益评价,对实现农业生态文明和耕地高效持续利用具有指导意义。结合能值分析、自相关等方法,评价和分析了2002~2011年武穴市耕地利用效益的时空演变特征。结果表明:近10a来武穴市耕地利用效益的能值投入和产出处于上升趋势,增长速度分别达58.17%和61.29%;能值投入中工业能值所占比重最大,超过总量的70%以上,2011年达到82.17%;耕地集约度增加6.60×1015sej的同时环境压力也在变大,耕地环境负载率由2002年的2.88上升至2011年的4.61;农业生产能力和农民生活水平不断提高;空间自相关结果显示武穴市各乡镇单位面积耕地能值投入和产出具有较明显的东高—南低—西平的聚集特征。研究结果对优化武穴市农业生产物化投入结构、提高产出效果,实现耕地高效持续利用具有一定的指导意义。     

滁州地区覆盖层厚度对场地地震动参数的影响

以滁州地区近百个钻孔资料为原型建立土层模型,采用一维频域等效线性化波动方法进行了土层地震反应分析,重点分析了覆盖层厚度对场地地震动参数的影响。研究结果表明,随着覆盖层厚度的增加,地表峰值加速度及土层放大系数逐渐增大,当覆盖层厚度超过一定值时,地表峰值加速度及土层放大系数呈逐渐缓慢减小的趋势;而反应谱特征周期总体上随着覆盖层厚度的增加而逐渐增大。     

太原市污灌区农田土壤中多环芳烃污染特征及生态风险评价

通过对污灌区农田土壤多环芳烃(Polycyclic Aromatic Hydrocarbons,PAHs)的分布特征、污染程度及来源进行解析,深入了解污水灌溉引发的土壤污染问题,实现污水灌溉农田土壤的污染预警和科学合理利用.在太原污灌农田共采集110个土壤样品,使用气相色谱-质谱仪(Gas Chromatography...