PM2.5 and water-soluble inorganic ion concentrations decreased faster in urban than rural areas in China

We investigated variations of PM_2.5 and water-soluble inorganic ions chemical characteristics at nine urban and rural sites in China using ground-based observations. From 2015 to 2019, mean PM_2.5 concentration across all sites decreased by 41.9 µg/m³ with a decline of 46% at urban sites and 28% at rural sites, where secondary inorganic aerosol (SIAs) contributed to 21% (urban sites) and 17% (rural sites) of the decreased PM_2.5. SIAs concentrations underwent a decline at urban locations, while sulfate (SO₄^2–), nitrate (NO₃^–), and ammonium (NH₄⁺) decreased by 49.5%, 31.3% and 31.6%, respectively. However, only SO₄^2– decreased at rural sites, NO₃^– increased by 21% and NH₄⁺ decreased slightly. Those changes contributed to an overall SIAs increase in 2019. Higher molar ratios of NO₃^– to SO₄^2– and NH₄⁺ to SO₄^2– were observed at urban sites than rural sites, being highest in the heavily polluted days. Mean molar ratios of NH₃/NH_x were higher in 2019 than 2015 at both urban and rural sites, implying increasing NH_x remained as free NH₃. Our observations indicated a slower transition from sulfate-driven to nitrate-driven aerosol pollution and less efficient control of NO_x than SO₂ related aerosol formation in rural regions than urban regions. Moreover, the common factor at urban and rural sites appears to be a combination of lower SO₄^2– levels and an increasing fraction of NO₃^– to PM_2.5 under NH₄⁺-rich conditions. Our findings imply that synchronous reduction in NO_x and NH₃ emissions especially rural areas would be effective to mitigate NO₃^–-driven aerosol pollution.     

Incorporating stakeholders’ preferences into a multi-criteria framework for planning large-scale Nature-Based Solutions

Hydro-meteorological risks are a growing issue for societies, economies and environments around the world. An effective, sustainable response to such risks and their future uncertainty requires a paradigm shift in our research and practical efforts. In this respect, Nature-Based Solutions (NBSs) offer the potential to achieve a more effective and flexible response to hydro-meteorological risks while also enhancing human well-being and biodiversity. The present paper describes a new methodology that incorporates stakeholders’ preferences into a multi-criteria analysis framework, as part of a tool for selecting risk mitigation measures. The methodology has been applied to Tamnava river basin in Serbia and Nangang river basin in Taiwan within the EC-funded RECONECT project. The results highlight the importance of involving stakeholders in the early stages of projects in order to achieve successful implementation of NBSs. The methodology can assist decision-makers in formulating desirable benefits and co-benefits and can enable a systematic and transparent NBSs planning process.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01419-4) contains supplementary material, which is available to authorized users.     

Cocky and climate smart? Climate change mitigation and place-branding in three Swedish towns

Sustainable development has emerged as a distinctive marker of place identity in addition to traditional markers such as buildings and spectacles. Climate change mitigation as a potential place brand, indicating sustainable development, is in focus of this article, comparing such efforts in three Swedish towns. Based on documentary studies and interviews, it demonstrates how one town has been successful in branding itself as “the Greenest City in Europe”, whereas mitigation efforts in two other towns are barely known outside the town halls. In the first case, a combination of material, symbolic, and institutional components has been decisive in establishing a brand with internal and external legitimacy. This case highlights the importance of a dedicated network of influential actors and a potent governance structure visualising the will of a town to make its climate mitigation efforts known. Despite similar material conditions, the two others come short on the symbolic and the institutional dimensions, although they may still have a potential for future success in terms of mitigation both in practice and as a marker of identity.     

Understanding the links between urban regeneration and climate-friendly urban development: lessons from two case studies in Japan

Urban regeneration policy and projects could facilitate the implementation of spatial policy responses to mitigate climate change and adapt to its consequences in cities. However, the potential role of urban regeneration in creating climate-friendly urban environments is not sufficiently evaluated and understood. Considering this gap, the paper aims to explore the potential linkage between urban regeneration and climate change. The case study analysis focuses on two urban regeneration projects, representing two major approaches of regeneration practices in Japanese cities, namely “project-based” and “plan-based” approaches. Research findings demonstrate that urban regeneration could help in reorganising existing urban areas in a climate-friendly manner. As a cross-cutting field of urban policy, urban regeneration could also help in creating synergies between mitigation and adaptation goals. Yet, achievement of such outcomes via regeneration projects necessitates the existence of an overriding urban development vision, political commitment, and willingness to implement binding and structural measures.     

Biomass for Fuel Cells: A Technical and Economic Assessment

Fuel cells can be highly efficient energy conversion devices. However, the environmental benefit of utilising fuel cells for energy conversion is completely dependent on the source of the fuel. Hydrogen is the ideal fuel for fuel cells but the current most economical methods of producing hydrogen also result in the production of significant amounts of carbon dioxide. Utilising biomass to produce the fuel for fuel cell systems offers an option that is technically feasible, potentially economically attractive and greenhouse gas neutral. High-temperature fuel cells that are able to operate with carbon monoxide in the feed are well suited to these applications. Furthermore, because they do not require noble metal catalysts, the cost of high-temperature fuel cells has the greatest potential to become competitive in the near future compared to other types of fuel cells. It is, however, extremely difficult to assess the economic feasibility of biomass-fuelled fuel cell systems because of a lack of published cost information and uncertainty in the predicted cost per kW of the various types of fuel cells for large volume production methods. From the scant information available it appears that the current cost for fuel-cell systems operating on anaerobic digester gas is about US$2,500 per kW compared to a target price of US$1,200 required to compete with conventional technologies.     

渭河咸阳段水环境有机污染负荷与环境容量分析

以COD为有机污染负荷指标,分析了渭河流域咸阳段有机污染负荷现状;同时根据该河段功能区划对应的地表水环境标准,核算了流域咸阳段现有排污口稀释混合区河长,以及该河段的水环境容量,最后讨论并制订了渭河流域咸阳段各排污口有机污染负荷削减方案:流域南岸1号和2号排污口在执行地表水IV、V类标准时,需要削减的COD污染负荷分别是147.095t/a和94.54t/a、130.05t/a和83.22t/a;北岸3号和4+号两个排污口需要关闭。     

中国旱作农田一氧化氮排放及减排:Meta分析

农田是大气污染物一氧化氮（NO）的主要排放源之一.与水稻田相比,旱作农田NO排放量和排放系数高,但其异质性及影响因素尚不明确.目前,我国农田NO排放和减排的研究以原位观测为主,缺乏系统的整合（Meta）分析.通过收集文献数据,定量分析玉米-冬小麦、水稻-冬小麦旱地阶段、蔬菜、茶园和果园等旱作体系NO排放量和排放系数的异质性及主要影响因素;定量评价减量施氮、有机肥替代化肥、配施新型增效氮肥和施用生物质炭等管理措施对NO排放量和排放系数的影响.收集相关文献共计49篇（发表于2006~2021年）.结果表明,玉麦轮作、茶园和果园体系年排放量平均值分别为1.44、7.45和0.92 kg ·hm^-2,在这3个体系间有显著性差异（P<0.05）,稻麦轮作旱地阶段和蔬菜季节排放量平均值分别为2.13 kg ·hm^-2和2.09 kg ·hm^-2.在玉麦轮作、稻麦轮作旱地阶段和茶园体系中,NO排放量均与施氮量呈正相关关系（P<0.01）,但在蔬菜和果园体系中二者无显著相关性.玉麦轮作、稻麦轮作旱地阶段、蔬菜、茶园和果园体系排放系数平均值分别为0.31%、0.71%、0.96%、1.74%和0.13%,除玉麦轮作分别与稻麦轮作旱地阶段和蔬菜体系间的差异不显著外（P>0.05）,在其余体系间均有显著性差异（P<0.01）.由于各体系间排放系数差异大,在编制区域或全国农田NO排放清单时,有必要对各作物体系采用不同的排放系数.减量施氮仅在减氮比例高于25%时可显著降低NO排放量（36%）,但对排放系数的影响不显著.由于减氮比例过高可能会造成作物减产,尚需进一步确定既不影响作物产量又降低NO排放的减氮比例.有机肥替代化肥在土壤有机碳含量低［ω（SOC）<15 g ·kg^-1］或酸性（pH<7）条件下以及配施新型增效氮肥在玉麦轮作农田中可显著降低NO排放量（-46%~-38%）和排放系数（-62%~-45%）,施用生物质炭的影响不显著.可为不同田间条件下分别采取有效的NO减排措施提供依据.     

充分发挥政府职能部门作用共同做好防震减灾工作

共同做好防震减灾工作,政府各职能部门要各司其职,各负其责仅靠领导重视及部门之间的密切配合还不够,必须用相应的制度做保证。还要通过不断的加强宣传,在各级领导的思想中树立起“经济建设与防震减灾工作同等重要”的观念。     

水泥工业的废弃物利用与CO2排放控制探讨

水泥工业不仅通过能源利用排放CO2 ,而且还是工业生产工艺过程中CO2 的最大非能源利用排放源。分析了水泥工业的发展现状及其能源消耗状况 ,计算了水泥工业的CO2 排放总量和分途径CO2 排放量 ,介绍了水泥工业的废弃物利用和控制水泥工业CO2 排放方面的一些具体技术 ,提出了一些针对水泥工业的CO2 排放控制措施和新型富氧燃烧技术应用于水泥工业的设想。     

水稻覆膜节水综合高产技术对稻田CH4排放的影响

采用静态箱-气相色谱法观测了常规栽培和水稻覆膜节水综合高产技术下川中丘陵地区稻田的CH4排放通量,探究覆膜节水综合高产技术对稻田CH4排放的影响。结果表明：整个水稻生长期,常规栽培与水稻覆膜节水综合高产技术稻田CH4排放总量分别为(35.0±3.5)和(5.1±1.0) g·m-2,后者较前者减少稻田CH4季节排放量的(86±4)%。二者CH4平均排放通量在不同水稻生长时期存在如下关系：孕穗期>抽穗期>成熟期>分蘖期。水稻各生长时期,覆膜节水综合高产技术均降低稻田CH4排放,在稻田CH4排放盛期（孕穗期）降幅达79%。在不同土壤水分状况下,水稻覆膜节水综合高产技术稻田CH4平均排放通量存在如下关系：烤田期>烤田后>烤田前;而常规栽培则为烤田期>烤田前>烤田后。不同于常规栽培,烤田对水稻覆膜节水综合高产技术下稻田 CH4排放无明显影响,烤田后降雨促进其 CH4排放。土壤水分状况由低变高更易促使覆膜节水综合高产技术下稻田CH4排放。覆膜节水综合高产技术栽培全生育期内,厢面CH4排放通量与土温、土壤Eh无显著相关性（P>0.05）。厢沟CH4排放与土温显著正相关（r=0.447*,P<0.05）。水稻移栽至烤田前,厢面CH4排放通量与土壤Eh显著负相关（r=0.624*,P<0.05）。