Effects of lipid concentration on anaerobic co-digestion of municipal biomass wastes

The influence of the lipid concentration on the anaerobic co-digestion of municipal biomass waste and waste-activated sludge was assessed by biochemical methane potential (BMP) tests and by bench-scale tests in a mesophilic semi-continuous stirred tank reactor. The effect of increasing the volatile solid (VS) concentration of lipid from 0% to 75% was investigated. BMP tests showed that lipids in municipal biomass waste could enhance the methane production. The results of bench-scale tests showed that a lipids concentration of 65% of total VS was the inhibition concentration. Methane yields increased with increasing lipid concentration when lipid concentrations were below 60%, but when lipid concentration was set as 65% or higher, methane yields decreased sharply. When lipid concentrations were below 60%, the pH values were in the optimum range for the growth of methanogenic bacteria and the ratios of volatile fatty acid (VFA)/alkalinity were in the range of 0.2–0.6. When lipid concentrations exceeded 65%, the pH values were below 5.2, the reactor was acidized and the values of VFA/alkalinity rose to 2.0. The amount of Brevibacterium decreased with increasing lipid content. Long chain fatty acids stacked on the methanogenic bacteria and blocked the mass transfer process, thereby inhibiting anaerobic digestion.     

晋东旱区农作物秸秆资源综合利用模式研究

系统分析了晋东丘陵旱农地区（寿阳）农作物秸秆资源及其利用现状,通过秸秆过腹还田生态系统物质循环；粪肥与秸秆配合还田、培肥土壤的定位试验；及其旱地水分利用效率等研究,获得秸秆过腹还田、农田休闲期秸秆覆盖、作物生育期秸秆覆盖和直接还田等４种利用途径的有关参数。以秸秆所产生的经济效益最大为目标函数,运用线性规划模型,优化秸秆综合利用结构,对北方旱地农作物秸秆资源综合利用具有一定的指导意义。     

北京地区渗灌条件下冬小麦田间土壤水分动态及节水机理的研究

根据对渗灌条件下冬小麦田间土壤水分、冬小麦生长发育状况及产量的观测 ,研究了渗灌条件下冬小麦田间土壤水分动态及节水机理。试验结果表明 ,渗灌条件下田间土壤水分动态变化与灌溉、冬小麦生长发育状况及气象条件密切相关 ;渗灌用于冬小麦灌溉可以明显起到节约灌溉用水的作用 ,并有利于冬小麦的生长发育及产量形成。在冬小麦的整个生育期 ,采用渗灌比喷灌田间耗水量减少了44 4mm ,灌溉用水节约了1200m3/hm₂ ,而最终产量提高了714kg/hm₂ ,渗灌条件下作物水分利用效率为21 11kg/(hm₂·mm) ,比喷灌条件下高4 49kg/(hm₂·mm)。渗灌用于冬小麦灌溉的节水机理主要表现为两个方面 :①每次灌溉后 ,地表湿度较喷灌条件下要小得多 ,减小了土壤水分的无效物理蒸发 ;②渗灌利于冬小麦根系向地中供水层 (20～120cm )延伸 ,提高了冬小麦根系对灌溉供水层的水分利用     

城市局部气候分区及其参数化条件下风环境模拟

在改善城市空气污染和城市热岛研究时,城市风环境研究受到人们关注。利用计算流体力学(CFD)的方法直接对城市尺度风环境进行模拟,将是一种高效的研究方法。本文对局部气候分区及其参数特征进行分析,针对中国城市化建筑高大化、密集化的特点以及多孔介质模型对城市下垫面参数化的要求,提出基于局部气候分区及其参数进行城市风环境数值模拟的方法,并以西安市西咸新区的沣西新城为例进行初步探讨。对沣西新城的模拟结果显示了本文方法的可行性,并对该区域通风廊道建设进行分析。     

人工湿地污水处理系统冬季植物的筛选与评价

选用25种冬季湿地植物进行了污水净化潜力筛选试验,并在综合应用原有湿地植物筛选与评价体系的基础上,增加植物逆境酶和基质酶指标,对试验植物进行了聚类分析.结果表明,测试植物的根系长度、活力、叶片丙二醛含量、生长量、氮磷浓度、氮磷的积累能力、根际基质脲酶活性与磷酸酶活性均存在显著差异.采用建立的净化潜力评价体系将测试植物聚类分为3大类,第1类净化力强,植物种类有水芹、油菜、灯芯草、虎耳草、德国鸢尾、桂花和花菖蒲,第2类净化力中等,植物种类有羽衣甘蓝、金盏菊、撒金珊瑚、女贞、红甜菜、杜鹃和大叶冬青,第3类净化力弱,植物种类有白菜、五月菊、月季、金鱼草、麦冬、葱兰、熊掌木、矮牵牛、小叶冬青、香石竹和红继木.     

旅游活动对岩溶地下水水质动态变化的影响——以重庆金佛山水房泉为例

为了更好地揭示岩溶地下水的影响因素,采用野外现场实测、自动观测、实验室分析相结合的方法,在"十一"旅游旺季对重庆金佛山水房泉流域各项理化指标进行连续监测。监测结果表明,岩溶地下水对外界条件反应敏感,其岩溶水理化性质容易受外界条件的影响,自然因素和人为因素的改变,可直接快速地改变地下水水质。旅游季节地下水水质发生明显变化,旅游因素对地下水质的变化有较好的响应关系。表现为旅游高峰前期的正常水平;旅游高峰期的骤然恶化,出现污染状况;旅游高峰后期,叠加降雨因素的影响从而使各个水质指标出现好转。     

我国大气铅浓度水平与污染源排放特征

总结和评价了我国大气铅浓度水平、大气铅污染源的主要类型和排放特征,对今后我国大气铅污染发展趋势进行了说明.汽油无铅化以后,我国城市大气环境中的铅浓度有所下降,一般不超过国家标准的限值,但农村地区大气铅污染状况应引起高度重视.涉铅工业排放、燃煤排放和汽车尾气是大气铅污染的主要来源.我国大气铅污染源涉及行业和部门庞杂,伴随着铅产品的整个生命周期.     

电子垃圾回收地得克隆的污染水平及分布特征

对浙江某电子垃圾回收地水体、沉积物、土壤以及大气中得克隆（DP）的污染水平及分布特征进行了调查。结果表明,水、沉积物、土壤和大气样品中均检测出了 DP,分别为0．843～1．56 ng/L,0．185～7．03 ng/g干重,0．115～26．4 ng/g干重和11．2 pg/m3;该区域 DP分布特征表明电子垃圾的拆解和焚烧是环境中 DP的重要来源。     

并流加料沉淀法处理含铜锌废水同时形成类水滑石污泥

分别采用传统沉淀法和并流加料沉淀法处理含铜锌废水,考察了废水进样速率、废水pH、搅拌速率对重金属离子残留质量浓度的影响。采用FTIR、XRD和SEM表征了所得污泥的物相和形貌。实验结果表明:并流加料沉淀法所得滤液中Zn~(2+)、Cu~(2+)和Al3+的质量浓度远低于传统沉淀法;在废水进样速率1.0 mL/min、废水pH 9、搅拌速率500 r/min的最佳工艺条件下,滤液中Cu~(2+)和Zn~(2+)基本没有残留,Al3+质量浓度仅为0.2 mg/L,达到工业排放标准;所得污泥结晶度良好,为类水滑石Cu_3Zn_3Al_2(OH)_(16)CO_3·4H_2O(PDF#37-0629)结构。     

Researching Visual Representations of Climate Change

This paper responds to calls for greater clarity about the application of theory and method in research on mediated communication about climate-change. Specifically, it identifies conceptual and methodological challenges for researching visual representations of climate change. We suggest current research is impeded by a lack of methodological explication and an unclear relationship between theories of visual meaning and the application of social science methods such as content analysis and frame analysis. As a first step towards addressing these issues, we review existing research to identify the methodological procedures that require explication in order to support the replication of studies and the comparison of findings. We then draw on the seminal work of Roland Barthes to examine how theories of visual meaning may be integrated into social-scientific research methods. Specifically, we demonstrate how Barthes’ concepts of denotation, connotation and mythology may be related to research concerns about the selection of visual content, the classification of image frames, audience responses, and analyses of ideological meaning. The conclusion highlights further possibilities for developing a robust form of visual analysis that meets the standards of social scientific research while addressing the fundamental insights about visual meaning derived from cultural theories of meaning.