Roles of benthic algae in the structure,function, and assessment of stream ecosystems affected by acid mine drainage

Tens of thousands of stream kilometers worldwide are degraded by a legacy of acid loads, high metal concentrations, and altered habitat caused by acid mine drainage (AMD) from abandoned underground and surface mines. As the primary production base in streams, the condition of algal‐dominated periphyton communities is particularly important to nutrient cycling, energy flow, and higher trophic levels. Here, we synthesize current knowledge regarding how AMD‐associated stressors affect (i) algal communities and their use as ecological indicators, (ii) their functional roles in stream ecosystems, and (iii) how these findings inform management decisions and evaluation of restoration effectiveness. A growing body of research has found ecosystem simplification caused by AMD stressors. Species diversity declines, productivity decreases, and less efficient nutrient uptake and retention occur as AMD severity increases. New monitoring approaches, indices of biological condition, and attributes of algal community structure and function effectively assess AMD severity and effectiveness of management practices. Measures of ecosystem processes, such as nutrient uptake rates, extracellular enzyme activities, and metabolism, are increasingly being used as assessment tools, but remain in their infancy relative to traditional community structure‐based approaches. The continued development, testing, and implementation of functional measures and their use alongside community structure metrics will further advance assessments, inform management decisions, and foster progress toward restoration goals. Algal assessments will have important roles in making progress toward improving and sustaining the water quality, ecological condition, and ecosystem services of streams in regions affected by the legacy of unregulated coal mining.     

The metabolism of U.S. cities 2.0

In the fifty years since Abel Wolman first published an estimate of U.S. urban metabolism, the field of urban metabolism has begun to thrive, with cities outside the United States being much of the focus. As cities attempt to meet local and international sustainability goals, it is time to revisit the metabolism of cities within the United States. Using existing empirical databases for material flows (the Freight Analysis Framework) and a published database on urban water flux, we provide a revised estimate of urban metabolism for the typical U.S. city. We estimate median values of metabolism for a city of one million people, considering water resources, food, fuel, and construction materials. Food consumption and waste production increased substantially to 3,800 metric tons per day and 4,900 metric tons per day, respectively. To facilitate a second generation of urban metabolism, we extend traditional analyses to include the embedded energy required to facilitate material consumption with important implications in determining sustainable urban metabolism. We estimate that a city of one million people requires nearly 4,000 gigajoules of primary energy per day to facilitate its metabolism. Our results show high heterogeneity of urban metabolism across the United States. As a result of the study, we conclude that there is a distinct need to promote policies at the regional or city scale that collect data for urban metabolism studies. Urban metabolism is an important educational and decision‐making tool that, with an increase in data availability, can provide important information for cities and their sustainability goals.     

Urban Water Mass Balance Analysis

Planning for “water‐sensitive” cities has become a priority for sustainable urban development in Australia. There has been little quantification of the term, however. Furthermore, the water balance of most cities is not well known. Following prolonged drought, there has also been a growing need to make Australian cities more water self‐reliant: to source water from within. This article formalizes a systematic mass‐balance framework to quantify all anthropogenic and natural flows into and out of the urban environment. Quantitative performance indicators are derived, including (1) degree of system centralization; (2) overall balance; potential of (3) rainfall, (4) stormwater, and (5) wastewater to offset current demand; and (6) water cycle rate. Using the method, we evaluate Sydney, Melbourne, South East Queensland and Perth using reported and modeled data. The approach makes visible large flows of water that have previously been unaccounted and ignored. It also highlights significant intercity variation. In 2004–2005, the cities varied 54% to 100% in their supply centralization, 257% to 397% in the ratio of rainfall and water use, 47% to 104% in their potential stormwater recycling potential, and 26% to 86% in wastewater recycling potential. The approach provides a practical, water‐focused application of the urban metabolism framework. It demonstrates how the principles of mass balance can help foster robust water accounting, monitoring, and management. More important, it contributes to the design and quantitative assessment of water‐sensitive cities of the future.     

Drivers of urban metabolism: Toward a framework for urban transformations

The environmental and social crises in cities call for radical future visions that can incite transformative change. Yet, urban metabolism research typically adopts an explanatory, retrospective approach to the drivers of urban flows and stocks, resulting in conservative, business-as-usual future outlooks. In this study, we present the results of a narrative literature review on drivers and futures of urban metabolism, and consequently use these results to propose and apply a framework that can be used by researchers (i) to systematically identify the drivers of urban metabolism, and (ii) to critically engage with these drivers for the development of transformative future visions. The framework comprises seven thematic categories of drivers (demographic, economic, cultural, political, technological, environmental, and infrastructural) and an eighth category (power) to be used as the lens through which the interactions between drivers, activities, and flows in the city are critically examined. Applying the framework to the case study of biowaste management in Rennes, France, we found it useful for the systematic identification of often overseen drivers. The proposed framework, allowing for a combined analysis of flows and drivers, can become a useful tool toward a solution-oriented urban metabolism research.     

基于能值分析方法的城市代谢过程——案例研究

城市代谢过程研究是实现城市生态规划和环境管理等实际工作优化与决策的关键理论问题之一。核算了1999-2006年北京代谢过程中能值通量和强度,并依照Eco-Indictor 99的划分标准,结合自然系统对污染物的自净化及污染对经济系统和生态系统的损害程度测度方法(DALY法和PDF法),从城市代谢生产过程和消费过程研究城市代谢对人群健康和自然生态系统的影响,结果表明:(1)北京城市代谢过程大部分依赖于外部购买的不可更新资源的消耗;(2)外部购买的不可更新资源主要依赖于它省的资源供给,对国外资源利用很少,说明北京是一个本国资源依赖性的城市,而且这种依赖程度在不断增长;(3)当前过快的城市代谢过程主要由固定资产建设所拉动,随着北京基础建设程度放缓,这种高依赖性的代谢模式会的到一定的改变;(4)在考虑生态损失的情况下其可持续发展水平有5%的下降。该研究克服传统外在预警式评价方法的局限,综合评价城市生态系统内在代谢过程及代谢水平,为城市生态规划和环境管理提供更为有效的优化与决策依据。     

城市食物磷足迹研究——以龙岩市为例

运用物质流分析法,以龙岩市为例,分析了1985—2010年城市食物磷代谢的变化,估算了食物磷足迹。研究表明,龙岩市总磷输入和总磷输出都有明显的增长(总磷输入从4110 t增加到12102 t,总磷输出从3855 t增加到11315 t);总磷足迹从6482t增加到20473 t,直接磷足迹的比例从53%下降到42%;而间接磷足迹的增速明显高于直接磷足迹;龙岩市在城市尺度上是重要的磷汇,在流域尺度上则是重要的磷源。磷足迹的研究有助于全面理解和评估城市磷代谢的特征;将磷足迹与磷流动分析结合,对我国磷资源和区域磷素管理调控具有指导意义。     

Achieving Dewaterization in Industrial Parks

Water resource management is a critical component of eco‐industrial parks. This article proposes a methodology, termed the water resource management model for industrial parks, that integrates a water input‐output table with water pinch technology. A case study of the Yixing Economic Development Zone (YEDZ) in China illustrates the methodology. Each sector's water utilization and direct and indirect intersectoral interactions of water and water pollutants in 2007 and 2015 are accounted for. It is proposed that water metabolism in 2015 could achieve certain objectives of water resource management in the YEDZ. In addition, future policies are proposed. The YEDZ needs to focus on improving various technologies regarding the manufacture of textiles, the manufacture of raw chemical materials and chemical products, and the production and supply of electric and heat power—which will promote the utilization of water cascading among sectors and encourage the reuse of treated water from wastewater treatment plants. Last, future work for water resource management is proposed.     

Quantifying a virtual water metabolic network of the Metropolitan District of Quito,Ecuador using ecological network methods

Current human population is mostly located in urban areas making cities the center of attention in terms of achieving sustainability goals. Evidence shows that ecosystems have evolved over time toward a balanced configuration between resource efficiency and functional redundancy. For this reason, they are exemplary models to follow in terms of sustainability. Here, we apply similar ecological network-based methods to study the virtual water metabolic network (VWMN) of the Metropolitan District of Quito. The VWMN was obtained using novel bottom-up, survey-based methods to generate the urban metabolic network. We compare the VWMN results with those previously obtained from ecological food webs, to learn if there are insights about the sustainability of urban metabolic processes. We conclude that VWMN does not exhibit characteristics observed in sustainable ecological networks because this socioeconomic network exhibits higher levels of path redundancy. Urban metabolism studies are gaining in popularity as a research tool aimed at informing resource management and this is one of the first covering a city in the Global South and using a bottom-up survey method.     

Progress and opportunities in advancing near-term forecasting of freshwater quality

Near-term freshwater forecasts, defined as sub-daily to decadal future predictions of a freshwater variable with quantified uncertainty, are urgently needed to improve water quality management as freshwater ecosystems exhibit greater variability due to global change. Shifting baselines in freshwater ecosystems due to land use and climate change prevent managers from relying on historical averages for predicting future conditions, necessitating near-term forecasts to mitigate freshwater risks to human health and safety (e.g., flash floods, harmful algal blooms) and ecosystem services (e.g., water-related recreation and tourism). To assess the current state of freshwater forecasting and identify opportunities for future progress, we synthesized freshwater forecasting papers published in the past 5 years. We found that freshwater forecasting is currently dominated by near-term forecasts of water quantity and that near-term water quality forecasts are fewer in number and in the early stages of development (i.e., non-operational) despite their potential as important preemptive decision support tools. We contend that more freshwater quality forecasts are critically needed and that near-term water quality forecasting is poised to make substantial advances based on examples of recent progress in forecasting methodology, workflows, and end-user engagement. For example, current water quality forecasting systems can predict water temperature, dissolved oxygen, and algal bloom/toxin events 5 days ahead with reasonable accuracy. Continued progress in freshwater quality forecasting will be greatly accelerated by adapting tools and approaches from freshwater quantity forecasting (e.g., machine learning modeling methods). In addition, future development of effective operational freshwater quality forecasts will require substantive engagement of end users throughout the forecast process, funding, and training opportunities. Looking ahead, near-term forecasting provides a hopeful future for freshwater management in the face of increased variability and risk due to global change, and we encourage the freshwater scientific community to incorporate forecasting approaches in water quality research and management.     

城市代谢效率研究的热点识别与综合效率实证研究

城市代谢是城市可持续发展研究的重要部分,其有序运行为城市发展与居民生活提供重要保障,代谢效率的提高有助于缓解资源利用与环境保护间的矛盾。通过分析国内外近30年的城市代谢效率的研究进展,整合代谢效率研究热点选取综合效率评估所需指标,并以深圳市为案例研究,结合数据包络分析（DEA）模型对城市物质代谢综合效率进行评估。结果表明：（1）近30年城市代谢研究处于蓬勃发展阶段,中国在相关研究领域中的影响力凸显,而城市代谢效率研究主要关注能源、水资源、碳氮元素及耐用物质（主要为建筑材料）等要素及其环境效应;（2）基于上述要素对深圳城市代谢的综合效率进行评估,其综合效率在2005-2017年间呈波动状态,多数年份城市代谢过程取得了高效运行（效率值大于1）,但仍存低效年份,包括2006（0.96）、2007（0.76）、2011（0.85）和2013（0.97）年,研究期间综合效率提高不明显。在资源投入与效益产出方面,深圳市在水资源利用效率方面需进一步提高;在当前资源消耗水平下经济效益仍有提高潜力;在减少碳氮元素的环境排放及建筑垃圾产生的效率方面有一定程度的提高。（3）通过城市代谢效率研究的热点识别,可明晰目前城市代谢综合效率评估所需涵盖的要素,由此建立评估体系可用于综合效率评估的实践,通过案例分析研究其反映城市资源利用效率动态的可行性,以期为城市可持续发展评估提供科学参考。     

基于灰水足迹的中国城市水资源可持续利用综合评价

随着城市化的快速发展,中国城市水资源面临着水资源短缺与水环境恶化等挑战,因此加强城市水资源可持续利用对于中国可持续发展具有重要意义。基于灰水足迹核算对2016年中国地级市水资源可持续利用情况进行综合评价。研究结果表明：（1）中国城市灰水足迹水平差异大,平均值为23.40×10⁸ m³,主要集中在20.00×10⁸ m³以下。中国城市农业源灰水足迹比例占比主要在70%以上,工业源比例占比主要在20%以下,而生活源比例占比在40%以下;（2）全国灰水经济生产率在12.45-857.31元/m³范围内,地区差异明显。33%城市灰水足迹荷载系数均大于1,全国地级市灰水足迹荷载系数平均值为1.16,城市水资源利用已对水环境产生污染压力,用水不可持续;（3）城市水资源开发率与灰水足迹荷载系数呈一定程度的正相关关系,说明了城市发展对水资源利用的"量"和"质"的压力作用具有一定的协同关系;（4）水资源可持续利用程度呈现大型城市 > 特大型城市 > 超大型城市 > 中小型城市,城市发展一定程度上有助于水资源的可持续利用,但发展规模过大可能会造成用水高产而护水低效的现象。因地制宜的实行水资源循环经济发展模式以及适时纳入灰水足迹核算与管理体系,是当前城市化大背景下实现水资源可持续利用的重要途径。     

城市生活垃圾代谢的研究进展

城市代谢是导致城市发展、能量生产和废物排放的社会、经济和技术过程的总和。生活垃圾管理系统是一类典型的、具备社会、经济、自然要素的复杂系统,它不仅同管理体制、技术水平和居民素质有关,也贯穿生产、消费、流通、还原过程,更和水体、土壤、大气、生物、矿产等自然环境紧密联系。综述了近年来基于城市生态系统代谢思路,在生活垃圾碳、重金属、营养元素和能量的城市代谢等方面的研究进展,分析了未来该领域研究需重点关注的方向。生活垃圾在城市生态系统中的能量流动、物质循环、代谢效率等方面的研究,可为生活垃圾管理系统的评价、规划、工程、管理研究提供科学基础。     

基于水敏性城市设计的城市水环境污染控制体系研究

随着城市化进程加快,自然地表被硬化的不透水地面所替代,城市面源污染加剧,城市水环境恶化成为限制城市发展的关键因素。水敏性城市设计(Water Sensitive Urban Design,WSUD)提出从城市设计和生态管理角度实现城市发展与水环境保护的共同目标。综述了WSUD理论内涵、设计原则、技术体系以及隐含在其中的生态学思想,提出当前WSUD理论发展需要进一步完善的技术体系,整合生态学思想以及建立科学的效益评估方法,并与传统生态智慧关联,为WSUD在我国的发展和研究提供科学参考。同时,基于WSUD技术及蕴含于其中的生态智慧,针对三峡库区城市水环境特点和城市面源污染特征,兼顾城市景观优化、生物生境再造、生态服务功能优化与城市建设协同发展,采取生态缓冲、湿地消纳和自然调控相结合的综合防控思路,以水陆界面生态屏障综合控制为主线,根据城市生活区-休闲娱乐区-水陆界面缓冲区3个空间层次,提出城市污染源头-滨湖绿带-生态护坡-基塘湿地-自然消落带多重拦截和消纳的城市水环境污染控制体系,形成三峡库区水敏性城市设计与建设的模版和参考,为三峡库区城市水体污染控制提供科学依据,促进三峡库区水质保护与城市人居环境协同发展。     

城市化对流域生态水文过程的影响研究综述

了解流域水文过程(水量和水质)是流域综合管理的基础。城市化引起的生态环境问题已成为目前和未来一段相当长的时期内人类社会面临的重大问题。然而,城市化(土地利用/覆被变化、新污染物产生)、水文(降水、入渗、蒸散、径流过程)和生态系统服务(产水服务、调节气候、土壤保持、初级生产力、维持生物多样性等)在不同时空尺度之间的相互作用还存在知识空白。从城市化对流域生态系统结构和功能的影响、城市化对地表能量平衡与水量平衡的影响、城市化对水质和水生生物的影响、以及城市土地利用/覆被变化的大气环境效应等多方面系统总结了城市化影响流域生态水文过程的研究进展。研究发现,城市"热岛"、"干岛"、暴雨径流引起的城市内涝、水污染等环境现象都与生态水文过程密切相关。强调现代城市规划需要遵循生态水文学规律,从全流域生态系统角度认识近年来新出现的不同尺度的城市环境效应。城市最佳管理措施应以流域为单元实施,以调节土地利用/覆被、保护湿地(包括自然与人工湿地)为手段,充分发挥自然生态系统调节功能(如植被蒸散和净化水质)。未来城市生态水文学应围绕"低影响开发"以及"基于自然的解决方案"等城市流域管理措施,在稳定城市小气候、缓解洪涝干旱等极端水文气象灾害风险以及减轻城市水污染等方面开展多尺度综合研究。     

关中平原城市群扩张对生态用地的多尺度影响

城市扩张与生态空间保护的矛盾是新型城镇化和国土空间规划过程中急需解决的问题之一。作为黄河流域生态保护与高质量发展的核心区域,关中平原城市群面临更加严峻的生态和资源胁迫。但相关研究主要对研究区整体的生态环境变化进行测度,少有研究分析城市群发展对生态用地的多尺度影响,且忽略了城市群中土地变化最剧烈,生态受胁迫最严重的城市边缘区。因此,基于土地利用数据,结合土地利用转移矩阵、景观指数、估算城市扩张间接影响的生态用地面积等方法,研究从城市群、重点城市和主要城市边缘区3个尺度分析1990-2018年城镇扩张对生态用地的直接和间接影响。结果表明：（1）关中平原城市群土地利用类型以半生态用地（耕地）为主,面积占比超过40%。而城市边缘区主要以半生态用地和建设用地为主。1990-2018年城市群建设用地面积比例由3.67%增长至5.93%,耕地面积共计减少3032.11 km²,自然生态用地的面积增加628.03 km²。受耕地占补、退耕还林等多重政策的影响,半生态用地和自然生态用地的变化呈现为"拉锯式"发展特征。（2）城市扩张对半生态用地的直接影响大于对自然生态用地的直接影响,各尺度土地利用转移变化大同小异,新增建设用地的主要来源均为耕地,其中城市边缘区的耕地受城镇扩张的挤占最为突出。（3）城市扩张对自然生态用地的间接影响大于直接影响,且不同城市建设用地对自然生态用地的间接影响因耕地补偿机制的不同而有所差异。因此,对关中平原城市群实施"一刀切"的耕地补偿政策实际上并不合理,应当因地制宜,考虑地区土地资源条件,适当调整发展和约束政策,更有利于城市群的可持续发展。     

干旱区典型绿洲城市发展与水资源潜力协调度分析

基于1995-2010年城市发展与水资源开发利用现状,构建了城市发展与水资源潜力的综合评价模型及二者的协调度模型,以探讨乌鲁木齐城市发展及水资源潜力的变化与二者的协调关系。结论如下:(1)乌鲁木齐市的城市发展综合水平基本呈逐年上升趋势,其中经济发展与人口增长是乌鲁木齐城市发展的主要形式,社会进步和空间扩张对城市综合发展的影响相对较小。(2)水资源开发利用潜力的变化波动性较强,总体呈现下降趋势,主要受水资源本底条件变化的影响,水资源利用效率和管理能力的提高则促进水资源潜力的提升。(3)城市发展与水资源系统的协调度先升后降,呈倒U字型变化,总体二者的协调发展度不高,城市发展系统和水资源系统的矛盾日渐突出。     

城市生态环境需水量研究--理论与方法

生态环境需水量是一个整合的新概念。从降水量概念和水资源量概念两个角度界定了城市生态环境需水量的概念与内涵 ,分析其类型和属性特征 ,建立了城市生态环境需水量的方法体系 ,包括城市分类的指标体系与方法、基于降水量概念和水资源量概念的城市生态环境需水量计算方法与等级划分方案 ,为城市生态环境需水量研究提供理论依据与方法支持     

城市生态基础设施管理研究进展

城市生态基础设施作为城市生态系统的重要组成部分,在维持自然生态过程稳定、促进社会经济发展、保障人居环境质量方面发挥着重要的作用。在快速城市化进程中,对城市生态基础设施进行科学的管理显得尤为重要。在重新明确城市生态基础设施管理概念和内涵的基础上,归纳提炼了4项管理原则,并对现有管理类型进行了梳理。对生态基础设施管理涉及的3个关键问题的常见解决方法进行了总结、分类,并对每类方法的优劣进行了分析讨论。针对此领域的工作做了展望。对于现有城市生态基础设施管理问题与方法的整合研究既有利于明确今后研究重点,也为城市生态基础设施管理提供了科学依据和案例参考。     

城市湿地公园使用者评价的影响因素及其行为偏好——以宜昌运河公园为例

城市湿地公园是城市水环境保护和市民活动的共同载体。如何达到保护城市水环境和满足使用者社会需求的平衡是本研究的关键问题。以景观绩效评价为基础,对宜昌运河公园的社会绩效进行了详细量化,并在调查结果上分析研究了影响城市湿地公园使用者评价的原因,以及在城市湿地公园内使用者的行为偏好和季节变化下使用者满意度和行为模式的变化情况,并提出了设计建议。结果表明,城市湿地公园的水环境治理目标与城市居民的公园服务需求是统一的。但是在公园生态和社会效益之间还是存在着冲突关系,如湿地面积和活动空间面积的权衡,消减河流污染物和维持公园水景质量的权衡以及湿地生境冬季景观效果不佳降低使用者满意度的情况。     

Net Zero Fort Carson: Integrating Energy,Water, and Waste Strategies to Lower the Environmental Impact of a Military Base

Military bases resemble small cities and face similar sustainability challenges. As pilot studies in the U.S. Army Net Zero program, 17 locations are moving to 100% renewable energy, zero depletion of water resources, and/or zero waste to landfill by 2020. Some bases target net zero in a single area, such as water, whereas two bases, including Fort Carson, Colorado, target net zero in all three areas. We investigated sustainability strategies that appear when multiple areas (energy, water, and waste) are integrated. A system dynamics model is used to simulate urban metabolism through Fort Carson's energy, water, and waste systems. Integrated scenarios reduce environmental impact up to 46% from the 2010 baseline, whereas single‐dimension scenarios (energy‐only, water‐only, and waste‐only) reduce impact, at most, 20%. Energy conserving technologies offer mutual gains, reducing annual energy use 18% and water use 15%. Renewable energy sources present trade‐offs: Concentrating solar power could supply 11% of energy demand, but increase water demand 2%. Waste to energy could supply 40% of energy demand and reduce waste to landfill >80%, but increase water demand between 1% and 22% depending on cooling system and waste tonnage. Outcomes depend on how the Fort Carson system is defined, because some components represent multiple net zero areas (food represents waste and energy), and some actions require embodied resources (energy generation potentially requires water and off‐base feedstock). We suggest that integrating multiple net zero goals can lead to lower environmental impact for military bases.