User pay financing of stormwater management: A case-study in Ottawa-Carleton, Ontario

Stormwater management upgrade and maintenance costs in the province of Ontario are significant. As capital grant programs decline, municipalities are exploring alternative means for financing the abatement of stormwater quantity and quality problems. User pay financing represents one such option. The economic, institutional and legal issues related to implementing user pay financing of stormwater management in Ontario are addressed using the Regional Municipality of Ottawa-Carleton (RMOC) as a case-study. The paper reviews the experience with user pay stormwater management programs in Canada and the USA, and recent stormwater issues and financing needs in the RMOC. The presented spreadsheet rate model is based on stormwater quantity and quality considerations and best management practices (BMPs) for various land-use categories. The modelling results vary depending on the inclusion or exemption of certain land-use categories and whether BMPs are implemented. Preliminary results indicate the monthly stormwater user charges are comparable with those charged in USA programs. In Ontario, existing statutes provide the enabling legislation for stormwater user charges, and there are no legal or regulatory barriers to implementing them. However, program we start-up costs and public perception could be significant obstacles to instituting user charges.     

基于多项污染物综合相对重要性的主成分子集合环境测点优选法

根据对多项污染物环境测点的优选,提出了单项污染物测值的相对重要性和多项污染物测值的综合相对重要性新概念,并给出了综合相对重要性的计算公式．根据测点的综合相对重要性,再用主成分子集合选择法优选测点该方法与基于交叉相关性的主成分子集合优选法相比,不仅减少了计算量,而且避免了当各单项污染物选出的测点不一致时,难以确定公共优化点的困难．该方法用于成都市大气污染物的12个测点优选结果符合实际情况．     

Within-plant allocation of a chemical defense in Secale cereale. Is concentration the appropriate currency of allocation?

Summary. The among-leaves allocation of DIBOA, a hydroxamic acid associated with plant resistance, in the shoot of rye (Secale cereale) was evaluated over the vegetative development of the plant. The appropriateness of using the concentration of secondary metabolites, DIBOA in this case, as the parameter to evaluate defense allocation in plants is discussed. Both biological and statistical arguments are put forward to suggest that allocation of chemical defenses should refer to absolute content and not to concentration. Results showed that leaf age was significantly linked to leaf concentration of DIBOA, young leaves having higher concentrations. In contrast, leaf content of DIBOA, our proposed currency of allocation, was not significantly higher in younger leaves. Furthermore, a regression analysis showed that the DIBOA content of leaves was better explained by the leaf relative biomass (proportion of shoot biomass) than by leaf biomass itself. It is suggested that, rather than leaf age, leaf relative biomass is the major factor determining DIBOA allocation in rye shoots. It is proposed that studies addressing within-plant defense allocation should use chemical defense content as the currency, emphasizing the major factors driving this process and its underlying mechanisms. Likewise, it is proposed that studies aiming at characterizing optimal patterns of plant defense should use chemical defense concentration as the currency, and be accompanied by evaluations of the actual resistance against herbivores of the plant parts analyzed, together with the effect on plant fitness. Received 19 February 1999; accepted 28 April 1999.     

城市物质代谢及其调控

对比研究了城市系统与自然生态系统物质代谢的主要差别。从现代控制论原理出发,对城市物质代谢涉及的主要因素及其相互关系进行了结构性分类研究,建立了城市物质代谢的控制论理论模型。      

城市河流重金属元素对降雨径流的动态响应

以海口市美舍河市区河段为研究对象,于2020年雨季分别采集降雨径流以及降雨径流汇入后的河流瞬时水样,测定并分析主要重金属元素的浓度及其变化规律,探讨其对降雨径流的动态响应。研究结果表明：降雨径流对河流可溶态污染元素质量浓度的贡献不突出,对可溶态锌（Zn）、砷（As）、镉（Cd）、硒（Se）具有一定稀释作用,排水口下游 3 m处是可溶态铬(Cr）、锰（Mn）、钴（Co）对降雨径流响应最显著区域;降雨径流对各悬浮态元素质量浓度贡献较大,排水口下游7 m处是绝大多数悬浮态元素对降〖JP〗雨径流响应最显著区域;Mn、Zn、Cr、镍（Ni）、As、Co、Cd 7种元素的总质量浓度对降雨径流的动态响应表现为先上升后下降。其中,排水口下游3 m处是Cr、As总质量浓度对降雨径流响应最显著区段,排水口下游7 m处是Mn、Co、Ni、Zn及Cd总质量浓度对降雨径流响应最显著区段。降雨径流对河流主要污染元素年输入总量估算结果表明,海口市建成区降雨径流向美舍河等受纳水体直接年输入量最大的是Mn和Zn,其次是Cr、As、Ni,Se与Cd的年输入量最小。     

几种果粮间作人工植物群落生物生产力的动态变化及其优化调控

为解决果粮间作经营的中后期常出现的作物减产和资源浪费的矛盾,有必要分析果粮人工植物群落中各生态元的时空变化过程,揭示果粮间作经营中矛盾的产生、发展乃至激化的过程,寻求合理的间作作物组合,并进行优化调控,在岷江上游干旱河谷区,选择处于不同经营阶段（３ａ,５ａ,１０ａ,１８ａ,２８ａ）而经营管理条件基本一致的的９种苹果与粮食作物间作模式,调查测定了每一模式各阶段的果树的生长及其苹果产量,各间作粮食作物的生物量、总生物量、作物固定的总能量及其光能利用率、经济产量和经济收入等指标,揭示了苹果和各粮食作物２８ａ内的生物生产力的动态变化及其特点,找到了果树不同经营阶段的合理间作物组合,提出了该区不同经营阶段的最佳模式类型．对果粮间作的作用、理论基础及优化调控指标及其不确定性等问题也进行了讨论     

基于最优尺度地理探测的长三角有机污染物时空分布驱动因素分析

场地污染对人体健康和生态环境造成了严重危害,理解其时空分布规律是污染评估和场地修复的基础.为此基于场地采样数据,利用最优尺度地理探测器分析长三角地区有机污染物时空分布规律及其驱动因素.结果表明:①长三角场地有机污染物空间分布存在显著的尺度效应,其最佳地理探测尺度格网为8000 m;②长三角污染物空间分布的主控因子最主要来源于生物场,其次来源于化学场;③在土壤0~20 cm深度,蔗糖酶含量、脲酶含量、微生物量氮、全氮含量和离子交换量等对有机污染物空间分布的解释力较大.在土壤20~40 cm深度,对有机污染物空间分布解释力较强的因子是土壤湿度、人口和全氮含量等.随着土壤深度的加深,水动力场的因子解释力增强.④春季里人口、全氮含量和多酚氧化酶含量等对有机污染物空间分布解释力较强.秋季里有机污染物的空间分布更复杂,因子之间表现出更强烈的非线性增强现象和双因子增强现象.     

基于最优传递矩阵的层次分析法在桥梁震害评估中的应用

影响桥梁抗震性能的因素众多,鉴于传统的定量方法无法精确权衡各因素的影响程度,因此,考虑将不确定型层次分析法引入桥梁的震害评估中,对区间标度的合理选择作了简要讨论,运用1～9标度采集数据,兼顾10/10～18/2标度的精确性,对初始判断矩阵进行折算。利用最优传递矩阵的概念,对传统的AHP进行改进,直接求出各指标的权重值。并将此方法应用到实例当中,建立基于地震波、墩台基础、支座、结构因素、环境因素等多因素影响下的桥梁震害评估模型,得到桥梁最终的综合评估值。     

城镇污水处理设施空间优化配置研究

城镇污水处理设施建设总体规模不足、空间布局不平衡等问题突出,基于效率最大化、费用最小化原则,从微观效率和宏观布局两个维度进行空间优化配置,为解决城镇污水处理设施的空间均衡问题提供思路.以淮安市盱眙县盱城镇为例,利用ArcGIS网络分析工具,构建"目标市场份额"和"最小阻抗"模型,进行镇区污水处理设施的空间优化配置.结果表明:已有的污水处理设施中,由于管网配套不足,富春运行负荷低,未来扩大服务范围、提高运行效率是重点;在合理运行条件下,已有的污水厂的设计能力仍不满足治理需求,根据排污治污缺口,需新建一座2万t/d规模的污水处理设施;新建污水厂的最佳位置位于缺口地区的最小费用点.微观效率与宏观布局的协同优化方案可为盱城镇污水处理设施的格局优化提供科学依据,同时也为全国同类地区城镇污水处理设施空间规划管理提供参考.