Using structural equation modeling to investigate relationships among ecological variables

Structural equation modeling is an advanced multivariate statistical process with which a researcher can construct theoretical concepts, test their measurement reliability, hypothesize and test a theory about their relationships, take into account measurement errors, and consider both direct and indirect effects of variables on one another. Latent variables are theoretical concepts that unite phenomena under a single term, e.g., ecosystem health, environmental condition, and pollution (Bollen, 1989). Latent variables are not measured directly but can be expressed in terms of one or more directly measurable variables called indicators. For some researchers, defining, constructing, and examining the validity of latent variables may be the end task of itself. For others, testing hypothesized relationships of latent variables may be of interest. We analyzed the correlation matrix of eleven environmental variables from the U.S. Environmental Protection Agency's (USEPA) Environmental Monitoring and Assessment Program for Estuaries (EMAP-E) using methods of structural equation modeling. We hypothesized and tested a conceptual model to characterize the interdependencies between four latent variables-sediment contamination, natural variability, biodiversity, and growth potential. In particular, we were interested in measuring the direct, indirect, and total effects of sediment contamination and natural variability on biodiversity and growth potential. The model fit the data well and accounted for 81% of the variability in biodiversity and 69% of the variability in growth potential. It revealed a positive total effect of natural variability on growth potential that otherwise would have been judged negative had we not considered indirect effects. That is, natural variability had a negative direct effect on growth potential of magnitude –0.3251 and a positive indirect effect mediated through biodiversity of magnitude 0.4509, yielding a net positive total effect of 0.1258. Natural variability had a positive direct effect on biodiversity of magnitude 0.5347 and a negative indirect effect mediated through growth potential of magnitude –0.1105 yielding a positive total effects of magnitude 0.4242. Sediment contamination had a negative direct effect on biodiversity of magnitude –0.1956 and a negative indirect effect on growth potential via biodiversity of magnitude –0.067. Biodiversity had a positive effect on growth potential of magnitude 0.8432, and growth potential had a positive effect on biodiversity of magnitude 0.3398. The correlation between biodiversity and growth potential was estimated at 0.7658 and that between sediment contamination and natural variability at –0.3769.     

京津冀地区经济发展与PM10浓度变化的灰色关联分析

近几年,京津冀地区因灰霾天气频发而备受关注。通过分析京津冀地区PM10浓度变化与主要经济指标的关系,查找京津冀地区空气污染原因,并为今后污染控制措施提供参考。采用灰色关联分析法,对2007—2012年京津冀地区PM10与GDP、钢铁产量、煤炭消费总量、原油消费总量、天然气消费总量5项经济指标进行了分析,结果表明,在与本地经济指标的关联度方面,京津冀地区、北京市、天津市的PM10与煤炭消费总量相关性高;河北省略有不同,钢铁产量为关联度最高的经济指标。在与京津冀地区经济指标的关联度方面,相比本地,北京市、河北省均呈现较大差异性,天津市差异性较小,说明北京市、河北省空气质量受自身影响较大,天津市空气质量受区域传输影响明显。建议整个京津冀地区均应重点加大"控煤"力度,天津市还需加强区域联防联控力度,河北省应加快钢铁企业转型升级,压缩过剩产能。     

Excitation-emission matrix (EEM) fluorescence spectroscopy for characterization of organic matter in membrane bioreactors: Principles,methods and applications

• Principles and methods for fluorescence EEM are systematically outlined. • Fluorophore peak/region/component and energy information can be extracted from EEM. • EEM can fingerprint the physical/chemical/biological properties of DOM in MBRs. • EEM is useful for tracking pollutant transformation and membrane retention/fouling. • Improvements are still needed to overcome limitations for further studies. The membrane bioreactor (MBR) technology is a rising star for wastewater treatment. The pollutant elimination and membrane fouling performances of MBRs are essentially related to the dissolved organic matter (DOM) in the system. Three-dimensional excitation-emission matrix (3D-EEM) fluorescence spectroscopy, a powerful tool for the rapid and sensitive characterization of DOM, has been extensively applied in MBR studies; however, only a limited portion of the EEM fingerprinting information was utilized. This paper revisits the principles and methods of fluorescence EEM, and reviews the recent progress in applying EEM to characterize DOM in MBR studies. We systematically introduced the information extracted from EEM by considering the fluorescence peak location/intensity, wavelength regional distribution, and spectral deconvolution (giving fluorescent component loadings/scores), and discussed how to use the information to interpret the chemical compositions, physiochemical properties, biological activities, membrane retention/fouling behaviors, and migration/transformation fates of DOM in MBR systems. In addition to conventional EEM indicators, novel fluorescent parameters are summarized for potential use, including quantum yield, Stokes shift, excited energy state, and fluorescence lifetime. The current limitations of EEM-based DOM characterization are also discussed, with possible measures proposed to improve applications in MBR monitoring.     

吉林省可再生能源战略环境评价指标体系的建立

本文依据“可再生能源法”和与吉林省可再生能源发展相关的政策、规划,提出了在进行可再生能源战略评价时评价指标建立的原则和建立方法以及指标体系权重的确定方法。通过对吉林省可再生能源的发展现状及可再生能源的主要构成情况进行分析,确定了吉林省可再生能源战略环境评价指标体系主要类型,并建立了吉林省可再生能源的战略环境评价指标体系的可选指标集。根据驱动力-压力-状态-影响-响应（DPSIR）指标框架,该指标体系主要包括驱动力指标、压力指标、状态指标、影响指标和响应指标,涉及经济、社会、环境指标和能源指标等4种类型。同时本文指出在指标确定过程中必须依据不同地域的特点,充分体现地域性的差别。     

区域旅游产业集群竞争力提升研究——以湘鄂渝黔边区为例

目前旅游产业集群现象已引起人们广泛的关注,提升区域旅游产业集群竞争力是发展区域旅游产业的关键。对国内外相关研究进行了简要的回顾,对旅游产业集群竞争力的影响要素进行了分析,构建了旅游产业集群的评价模型,并以湘鄂渝黔边区域旅游产业集群为例,提出了提升区域旅游产业集群竞争力的对策。     

中国低碳城市热思考:现状、问题及趋势

近年来我国掀起了一股低碳城市建设热潮。但在这股热潮背后,还有许多尚不明晰的问题需要理性思考。围绕低碳城市相关议题,开展了如下5方面工作:①解读低碳城市概念,指出低碳城市建设是一个多目标问题,要以低碳经济为基础,并实现经济发展、生态环境保护、居民生活水平提高等目标的共赢;②概括低碳城市评价指标,指出针对指标还没有建立明确的标准;③从城市规划、低碳政策、生态产业、可持续能源、绿色交通等方面总结了保定、上海、吉林、杭州等城市的低碳建设途径;④分析城市低碳发展现状水平评价结果,指出低碳城市建设还有很大的提升空间;⑤最终在分析低碳城市建设尚存不足的基础上,提出今后需深化认识的几个问题,如不能因低碳而放弃其它城市发展目标,低碳城市建设要因地制宜,低碳城市是一项长期、复杂的系统工程,需各领域专家通力协作,需从系统规划、阶段性方案实施、实施后评估与修订等环节进行全生命周期跟踪管理。希望这些思考能对我国低碳城市建设的顺利推进起到积极作用。     

垃圾填埋场加速稳定化表征指标的相关性分析

加速稳定化表征指标是生物反应器填埋技术评价的重要内容。通过垃圾填埋室内模拟实验,研究不同运行工况下垃圾挥发性固体(VS)、生物可降解物(BDM)、纤维素(C)和纤维素/木质素(C/L)等组分指标的动态变化规律及其对加速稳定化进程的指示作用,进而探寻各指标之间的相关性,进一步筛选确定垃圾填埋场加速稳定化进程的核心表征指标。结果表明,垃圾组分VS、BDM、C和C/L的衰减符合一级反应动力学,其动态变化能够较为灵敏地指示渗滤液回灌和通风供氧对垃圾稳定化的显著加速作用,可作为垃圾填埋场加速稳定化进程的表征指标。VS、BDM、C和C/L相互之间具有良好的正线性相关性。BDM和C/L适宜作为垃圾填埋场加速稳定化进程的核心表征指标。     

南通市沿海开发水资源保障能力评价研究

以工程保障、社会经济保障、环境保障和效率保障作为南通市沿海开发水资源保障能力评价的准则层,以缺水率、有效灌溉面积率、单位GDP用水等12个指标作为指标层构建了南通市沿海开发水资源保障能力综合评价指标体系。采用层次分析法和专家评分法确定指标权重,通过加权平均确定综合评价值。评价结果为：南通市现状综合保障能力中等,未来在充分节水、保护环境、提高用水效率的前提下,水资源保障能力将有所提高。从分类保障情况看,全市工程保障能力最好而环境保障能力最差;从各行政区的保障能力看,如皋市综合保障能力最好,而海安和如东两县综合保障能力最差。最后对如何提高各地区水资源综合保障能力作了讨论     

Phospholipid fatty acid patterns of microbial communities in paddy soil under different fertilizer treatments

The microbial communities under irrigated rice cropping with different fertilizer treatments, including control （CK）, PK, NK, NP, NPK fertilization, were investigated using phospholipid fatty acid （PLFA） profile method. The results of this study revealed that the fertilizer practice had an impact on the community structure of specific microbial groups. The principal components analysis （PCA） showed that proportion of the actinomycete PLFAs （10Me 18：0 and 10Me 16：0） were the lowest in the PK treatment and the highest in the NPK treatment, which means that soil nitrogen status affected the diversity of actinomycetes, whereas nitrogen cycling was related to the actinomycets. Under CK treatment, the ratio of Gram-positive to Gram-negative bacteria was lower compared with that in fertilizer addition treatments, indicating that fertilizer application stimulated Gram-positive bacterial population in paddy soil. The fatty acid 18：2to6,9, which is considered to be predominantly of fungal origin, was at low level in all the treatments. The ratio of cyl9：0 to 18：1 to7, which has been proposed as an indicator of stress conditions, decreased in PK treatment. Changes of soil microbial community under different fertilizer treatments of paddy soil were detected in this study; however, the causes that lead to changes in the microbial community still needs further study.     

基于熵权法改进的综合污染指数的水质评价——以白云湖为例

以白云湖为例,于2016年12月(枯水期)、2017年5月(平水期)和2017年9月(丰水期)分别采集水样并测定了10种水质指标,采用单因子评价方法和综合污染指数法分析了白云湖在枯水期、平水期和丰水期的水质状况及不同湖区的污染水平,并结合熵权法和单因子评价方法构建了基于熵权法改进的综合污染指数,对白云湖进行了综合水质评...