对河流生态健康状况进行评价,可为河流治理和生态修复提供依据.基于2018年8—9月天津市河流现场调查获取的物理、化学和生物群落指标（浮游动物、浮游植物、底栖动物、鱼类、水生大型植物、陆生植物）数据,构建包含物理完整性、化学完整性和生物完整性在内的河流IEI（index of ecological integrity,生态完整性指数）评价体系,对天津市河流生态健康状况进行评价.根据生物栖息地评分和水质状况确定参照点位,采用标准化方法筛选候选指标,应用层次分析法计算三部分指标权重,最终得出天津市河流生态健康评价结果.结果表明:①IEI评价结果显示,天津市河流生态健康状况等级为“健康”的样点占18.8%,“较好”的样点占28.1%,“一般”的样点占40.6%,“较差”的样点占6.3%,“差”的样点占6.3%,天津市河流生态健康状况整体处于“一般”水平.②相关性分析表明,ρ（NH4+-N）和ρ（CODMn）超标是造成天津市水质达不到功能区标准的主要原因,同时也是影响河流生态健康的主要因素.研究显示,IEI评价法能够较为敏感地响应研究区面临的环境压力,适用于评价研究区河流生态健康. 相似文献
This study explored the national hydrogen refueling infrastructure requirement along major United States (US) interstate highway corridors to support the deployment of fuel cell electric trucks (FCETs) for the national long-haul trucking fleet. Given the long-haul trucking shipment demand in 2025 projected by the Freight Analysis Framework, locations and capacities of hydrogen stations were identified for inter-zone freight flows, and the total daily refueling demand was estimated for intra-zone flows for each FAF zone. Based on the infrastructure deployment results, we conducted an economic feasibility analysis of FCETs by evaluating the total ownership cost. We found that when the FCET penetration is relatively high (e.g., 10% penetration), FCETs become more competitive in terms of fuel cost and idling cost and could be economic viable if the incremental vehicle cost is reduced to meet the near-term FCET technology cost targets and the liquefaction cost is reduced to an optimal case. We also observed that the station cost depends on regional factors, particularly regional demand, which is used to determine station capacity. Thus, one possible strategy for station roll-out is to have early investment in target regions where station costs are expected to be relatively low such as the Pacific and West South Central regions.
