Considerations for using alternative technologies in nutrient management on Cape Cod: Beyond cost and performance

Mitigating non-point source nitrogen in coastal estuaries is economically, environmentally, logistically, and socially challenging. On Cape Cod, Massachusetts, nitrogen management includes both traditional, centralized wastewater treatment and sewering as well as a number of alternative technologies. We conducted semi-structured interviews with 37 participants from governmental and non-governmental organizations as well as related industries to identify the barriers and opportunities for the use of alternative technologies to mitigate nitrogen pollution. The interviews were recorded, transcribed, and then analyzed using content analysis and rhetorical analysis. Cost and technical capacity to reduce nitrogen were the most discussed considerations. Beyond those, there were a slew of additional considerations that also impacted whether a technology would be installed, permitted, and socially accepted. These included: maintenance and monitoring logistics, comparisons to sewering, co-benefits, risk/uncertainty, community culture, extent of public engagement, permitting/regulatory challenges, and siting considerations. The insights about these additional considerations are valuable for transferring to other coastal areas managing nutrient impairments that may have not yet factored in these considerations when making decisions about how to meet water quality goals.     

北京地表水中三氟乙酸的测定

三氟乙酸是HFC-134a等氯氟烃替代品的降解产物,对植物和土壤微生物群落的生长有一定抑制作用。笔者建立了测定TFA质量浓度的实验方法:将样品中的三氟乙酸与硫酸二甲酯在浓硫酸介质中衍生为三氟乙酸甲酯(MTFA),利用MTFA的易挥发性,以顶空进样和气相色谱-质谱联用的方法检测样品中MTFA的质量浓度,进而得到环境水样中TFA的质量浓度。并应用该方法测定了北京部分地表水体中三氟乙酸的质量浓度。测定结果:北京青年湖水样和北海水样中的ρ(三氟乙酸)分别为78和93ng L,而北京大学自来水水样中ρ(三氟乙酸)低于方法检测限10ng L。      

Co-creating an alternative: the moral economy of participating in farmers’ markets

Growing dissatisfaction with the globalised food system, articulated on the behalf of both producers and consumers, has caused a variety of public debates surrounding the ethics of food production and consumption to become increasingly visible in society over the last two decades. Simultaneously, farmers’ markets (FMs) and other forms of direct marketing have experienced a noteworthy increase in participants, indicating an emerging demand for an alternative to conventional food networks, alternatives that are often perceived as providing a more just and moral relationship to food production and consumption. This study examines consumer and producer motivations for participation in FMs and opinions towards conventional and alternative agriculture in order to elucidate what (if any) values and morals are shared among producers and consumers. This study draws upon the theoretical framework of moral economy to understand whether these shared values suggest FM participants are working to co-create an alternative economy based on “moral” principles such as fairness, justice, and reciprocity. This mixed-methods study consists of consumer surveys (N?=?377) and semi-structured interviews with producers (N?=?17) from five FMs in the state of Delaware. The results suggest that producer and consumer motivations to participate in FMs, particularly a shared emphasis on social value, are indicative of a sense of moral economy. However, this moral economy is complicated by tension towards consumers and the alternative food movement more generally expressed on behalf of producers.     

资源型城市统筹规划的思考与建议

以编制区域循环经济发展规划为主线,概述了我国循环经济发展的总体趋势和资源型城市经济转型试点的接续产业发展规划;探索性地提出制定循环经济产业基地集聚区建设规划的工作思路;强调发挥政府规划和投融资政策的引导作用,以及建立产业政策体系和激励机制的必要性。     

污泥酵制园林营养土好氧-厌氧交替法可行性分析

为研究好氧-厌氧交替法用于脱水污泥酵制园林营养土达到无害化、营养化、腐殖化(三化)目标的可行性,开展了好氧、厌氧、交替实验效果分析。结果表明:大肠菌群死亡率,酵温50℃时为80%,60℃时为95%;好氧、厌氧、交替,冬季最高酵温分别为52.5、29.5、52.2℃(夏季分别为62.5、41.8、64℃),大肠菌群达标所需时间好氧、交替均为8 d(冬)和3d(夏),厌氧28 d以上;平均碱解氮,厌氧0.859 g/kg>交替0.856 g/kg>好氧0.798 g/kg;20 d后平均有效磷,交替1.852g/kg>好氧1.692 g/kg>厌氧1.636 g/kg;20 d后平均有效钾:交替14.215 g/kg>好氧13.187 g/kg>厌氧11.945 g/kg;20d后平均腐殖质,交替10.510 g/kg>厌氧9.398 g/kg>好氧8.768 g/kg。分析可知,好氧法、交替法可使发酵污泥达到无害化,营养化、腐殖化指标交替法高于好氧法,交替法用于污泥酵制园林三化营养土可行,其控制参数需实验确定。     

含氧柴油对柴油机排放及细颗粒物碳质组分的影响

乙缩醛(1,1-diethoxyethane)与柴油互溶性好, 可替代乙醇作为生物质来源的柴油含氧添加成分. 生物柴油掺混可以提高乙缩醛和柴油混合燃料的闪点及含氧量. 在柴油发动机台架上, 考察柴油和2种含氧柴油(10%乙缩醛+90%柴油和10%乙缩醛＋10%生物柴油＋80%柴油)在2个固定转速不同负荷的5个工况点的排放特性, 分析了NO_x、HC、CO和PM_2.5排放情况, 并用DRI的碳分析仪分析了PM_2.5中的碳质组分.结果表明, 与普通柴油排放相比, 含氧柴油对NO_x排放速率的影响不大, 在某些工况点HC排放速率有较显著的增加. 含氧柴油降低了柴油机PM_2.5排放速率, 最大降低幅度29%. 从碳质组成上看, 含氧燃料降低了PM_2.5中总碳 (total carbon,TC) 的排放速率, 最大降低幅度24%. 含氧柴油的元素碳(elemental carbon,EC)排放速率普遍低于普通柴油; 有机碳(organic carbon,OC)的排放速率在发动机高转速工况时明显低于普通柴油; PM_2.5的OC/EC值在大多数工况下高于普通柴油. 3种燃料排放PM_2.5的碳质组成百分比相似, OC和EC主要为OC1和EC1. 含氧柴油降低了柴油机PM_2.5的排放速率, 颗粒物中OC的比例有所增加, 但对颗粒物的碳质组分组成没有明显的影响.     

Knowledge-based decision-making model for the management of transit system alternative fuel infrastructures

Energy-efficient and environmentally sustainable public transportation systems are within the solution space provided by alternative fuel vehicles. Given the large revenue service potential of alternative fuel buses within the urban space, they are good candidates for emissions reductions when they are employed as part of a comprehensive urban transit planning process. The determination of the most appropriate alternative fuel bus asset for a given application is not necessarily that straightforward. The typical bus fleet is developed over a broad time horizon with each asset being acquired to meet a certain agency need or to close a perceived gap in the delivery of public transportation service. Therefore, as new assets are considered, it is critical for the fleet manager to consider as many factors of the fleet infrastructure to better ensure the positive impact that the newly acquired asset will have on fleet performance relative to the overall service goals and objectives of the fleet. This study investigates a broad range of alternative fuel bus technologies and the associated factors that will inform the decision-making process. Further, this work utilizes the inventory and understanding of the range of technology factors and leverages the perspective knowledge of industry experts on each of these factors to develop an expert systems decision-making philosophy to aid in the adoption of industry standards, best practices, consistency and sustainability in fleet asset management over time.     

基于SSA-BP与SSA的地下水污染源反演识别

应用基于SSA-BP神经网络替代模型的模拟-优化方法和SSA研究了地下水污染源位置及释放历史的反演识别问题。并在建立地下水水流模型时,应用Cholesky分解方法建立含水层渗透系数连续场,该方法相比于普通的参数分区方法更好地描述了水文地质参数的非均质性。结果表明:SSA-BP神经网络替代模型对模拟模型具有较高的逼近精度,其平均相对误差仅有3.21%。应用SSA求解优化模型,能够快速准确地识别出点污染源的位置及释放历史。SSA对污染源位置的反演识别相对误差在10%左右,对污染源源强的反演识别相对误差不超过4%。因此,本文所提出的方法是一种有效的地下水污染源识别方法,可为污染责任认定及污染修复方案的优化提供参考。     

平遥双林寺彩塑——另类曲线美

平遥双林寺彩塑是一种以佛教为题材、世俗形象的民间艺术。彩塑塑造方法虽然也是写实主义,但却有独特的塑造风格,民间艺人采用夸张的曲线线条来体现一种力量型的另类曲线美感。以天王殿四大金刚及著名的千佛殿里韦驮做主要的观察对象,探讨了平遥双林寺彩塑独特的塑造技术和对线条音律的运用能力。