杭州地区大气CO2体积分数变化特征及影响因素

选取2015年8月至2016年9月杭州城区、远郊地区在线观测CO_2体积分数,分析杭州地区CO_2体积分数的城郊差异,并结合风向、CO_2体积分数周末效应、二十国集团(G20)峰会期间CO_2体积分数变化过程分析,探讨杭州城市对CO_2体积分数的影响程度.结果表明,杭州城区、远郊地区CO_2体积分数的日变化分布以单峰型形态为主,植物光合作用/呼吸作用和大气输送条件的日变化是主要的影响因素;城郊CO_2体积分数差值表现为双峰形态,人为排放对城郊CO_2体积分数差值的日变化分布存在重要影响.CO_2体积分数日变化幅度在春夏季节远郊地区大于城区,秋季则反之.杭州城区、远郊地区CO_2体积分数的季节变化趋势基本一致,均表现为冬、春季高,夏季低;城郊CO_2体积分数差值冬季最高,夏季最低.杭州地区CO_2体积分数高值的输送方向与周边城市区域的分布方向一致.杭州城区、远郊地区CO_2体积分数均呈现周末效应,尤其在城区,机动车排放对工作日-周末CO_2体积分数的日变化分布存在影响.杭州城区CO_2平均体积分数比远郊地区高9.3×10-6,G20峰会期间人为源排放的减少有效地降低了大气CO_2体积分数,尤其对市区的削减效果更为明显.     

城市综合管廊燃气舱室输气管道泄漏扩散规律研究

为了掌握输气管道在城市综合管廊舱室泄漏扩散的基本规律,采用FLUENT软件,针对管廊正常通风—泄漏报警—事故通风—警报解除的全过程进行动态分析。首先在正常通风速度建立的稳态风场中,模拟天然气在不同管输压力下发生小孔泄漏后的报警时间,根据首个响应的报警器的位置判断泄漏源位置。结果表明,当泄漏孔径为20 mm,通风速度为1.92 m/s,且泄漏源处于2个报警器中间时,管输压力为200,400,800 kPa时对应的报警时间分别为10.4,6.7,4.5 s。事故通风速度下,对不同管输压力的天然气扩散进行分析,当天然气朝逆风侧扩散时,随动量逐渐减小而到达不同的边界坐标。同时,环境大气压的降低不仅会缩短报警器的首次报警时间,还能延长总扩散距离。预测所得的天然气爆炸上下限浓度区移动速度有助于动态了解处于爆炸上下限浓度之间气体的实时位置。解除报警时间与进风口风速呈近似线性关系,可为现场救援队伍选择经济通风量提供理论指导。     

埋地输氢管道泄漏爆炸事故后果模拟分析

为了输氢管道的安全建设与运营,基于计算流体力学FLACS软件,模拟了埋地输氢管道在半受限空间内的泄漏爆炸事故后果,探讨了泄漏孔径、泄漏时长、输氢压力和环境风速对爆炸事故后果的影响规律,并得出相应的危险区域。结果表明:泄漏孔径、输氢压力和最大爆炸超压均与危险区域呈正相关关系,泄漏时长对事故后果几乎无影响;随着输氢压力的增大,危险区域受建筑物和风速的影响更为明显,在建筑物附近形成了狭长的危险区域带;最大爆炸超压和危险区域随环境风速的增大均呈现出先增大后减小的趋势。     

基于因子分析的嫩江重要省界缓冲区水质评价研究

嫩江流域省界缓冲区水质监测与评价,是针对2010年和2015年引起嫩江省界缓冲区水环境质量主要污染物的变化分析,判断主要超标指标为有机生化指标。为进一步明确嫩江缓冲区水质影响关键因子,采用因子分析评价嫩江重要省界缓冲区水质状况。依据因子的荷载矩阵,2010年和2015年的主导因子均累计解释了原始向量80%以上的信息,反映了这两年水环境和污染因子之间的关系。嫩江流域省界缓冲区流域水质状况分析,为今后对嫩江流域水功能区目标管理提供理论支持。     

Advanced treatment of municipal wastewater by nanofiltration: Operational optimization and membrane fouling analysis

Municipal sewage from an oxidation ditch was treated for reuse by nanofiltration (NF) in this study. The NF performance was optimized, and its fouling characteristics after different operational durations (i.e., 48 and 169 hr) were analyzed to investigate the applicability of nanofiltration for water reuse. The optimum performance was achieved when transmembrane pressure = 12 bar, pH = 4 and flow rate = 8 L/min using a GE membrane. The permeate water quality could satisfy the requirements of water reclamation for different uses and local standards for water reuse in Beijing. Flux decline in the fouling experiments could be divided into a rapid flux decline and a quasi-steady state. The boundary flux theory was used to predict the evolution of permeate flux. The expected operational duration based on the 169-hr experiment was 392.6 hr which is 175% longer than that of the 48-hr one. High molecular weight (MW) protein-like substances were suggested to be the dominant foulants after an extended period based on the MW distribution and the fluorescence characteristics. The analyses of infrared spectra and extracellular polymeric substances revealed that the roles of both humic- and polysaccharide-like substances were diminished, while that of protein-like substances were strengthened in the contribution of membrane fouling with time prolonged. Inorganic salts were found to have marginally influence on membrane fouling. Additionally, alkali washing was more efficient at removing organic foulants in the long term, and a combination of water flushing and alkali washing was appropriate for NF fouling control in municipal sewage treatment.     

Organic aerosol molecular composition and gas–particle partitioning coefficients at a Mediterranean site (Corsica)

Molecular speciation of atmospheric organic matter was investigated during a short summer field campaign performed in a citrus fruit field in northern Corsica(June 2011). Aimedat assessing the performance on the field of newly developed analytical protocols, this work focuses on the molecular composition of both gas and particulate phases and provides an insight into partitioning behavior of the semi-volatile oxygenated fraction. Limonene ozonolysis tracers were specifically searched for, according to gas chromatography–mass spectrometry(GC–MS) data previously recorded for smog chamber experiments. A screening of other oxygenated species present in the field atmosphere was also performed. About sixty polar molecules were positively or tentatively identified in gas and/or particle phases. These molecules comprise a wide range of branched and linear, mono and di-carbonyls(C_3–C7),mono and di-carboxylic acids(C_3–C_18), and compounds bearing up to three functionalities.Among these compounds, some can be specifically attributed to limonene oxidation and others can be related to α- or β-pinene oxidation. This provides an original snapshot of the organic matter composition at a Mediterranean site in summer. Furthermore, for compounds identified and quantified in both gaseous and particulate phases, an experimental gas/particle partitioning coefficient was determined. Several volatile products, which are not expected in the particulate phase assuming thermodynamic equilibrium, were nonetheless present in significant concentrations. Hypotheses are proposed to explain these observations, such as the possible aerosol viscosity that could hinder the theoretical equilibrium to be rapidly reached.     

Temporal and spatial changes of microbial community in an industrial effluent receiving area in Hangzhou Bay

Anthropogenic activities usually contaminate water environments, and have led to the eutrophication of many estuaries and shifts in microbial communities. In this study, the temporal and spatial changes of the microbial community in an industrial effluent receiving area in Hangzhou Bay were investigated by 454 pyrosequencing. The bacterial community showed higher richness and biodiversity than the archaeal community in all sediments. Proteobacteria dominated in the bacterial communities of all the samples; Marine_Group_Ⅰ and Methanomicrobia were the two dominant archaeal classes in the effluent receiving area. PCoA and AMOVA revealed strong seasonal but minor spatial changes in both bacterial and archaeal communities in the sediments. The seasonal changes of the bacterial community were less significant than those of the archaeal community, which mainly consisted of fluctuations in abundance of a large proportion of longstanding species rather than the appearance and disappearance of major archaeal species. Temperature was found to positively correlate with the dominant bacteria, Betaproteobacteria, and negatively correlate with the dominant archaea,Marine_Group_Ⅰ; and might be the primary driving force for the seasonal variation of the microbial community.     

面向流域水质安全预警的土地开发压力源评估方法及其应用

为适应水环境风险管理中压力源风险的快速识别需求,构建了土地开发压力源评估方法,并以三峡库区为案例区进行应用研究. 土地开发压力源评估方法首先是基于不同土地利用类型的排污参数来确定敏感土地利用类型和不利转移方向,再采用状态和趋势兼顾的原则筛选流域内敏感单元,然后根据各单元的实际特征逐一确定预警指标,以进行压力源评估和预警级别划分. 案例研究结果表明:重庆市辖区控制单元、涪陵区万州区控制单元和澎溪河开县控制单元是库区水质安全预警的3个敏感单元;其中,重庆市辖区控制单元和涪陵区万州区控制单元的预警指标均为敏感土地类型面积比例和发生不利转移的土地面积比例,其中重庆市辖区控制单元的2个预警指标值分别为42.17%、3.43%;涪陵区万州区控制单元分别为32.86%、1.74%;而澎溪河开县控制单元的预警指标仅为敏感土地类型面积比例,其值为32.31%. ③重庆市辖区控制单元、涪陵区万州区控制单元和澎溪河开县控制单元的预警指标最大超标率分别为163%、33%和19%,相应各单元土地开发压力分别为红色预警(重警)、橙色预警(中警)和黄色预警(轻警)级别. 从管理意义上,重庆市辖区控制单元和涪陵区万州区控制单元未来需要从优化当前土地利用方式、合理控制未来土地开发的双重角度来降低压力;澎溪河开县控制单元未来应重点关注和降低当前土地利用状况对水质安全的压力. 研究认为,所提出的面向流域水质安全预警的土地开发压力源评估方法具有可操作性,其案例研究结果可为三峡库区案例区水环境风险管理提供决策支撑.      

我国典型陆地生态系统固碳重要区范围界定

全球变暖已成为当今最主要的全球性环境问题之一,建立固碳重要区也是应对全球气候变化的重要途径之一.根据我国陆地生态系统现状以及固碳相关的最新研究结果和政府文件,以森林、草地生态系统为主要研究对象,采用GIS空间叠置分析方法,界定我国典型陆地生态系统固碳重要区(注:涉及“全国”的各要素范围均未包含港澳台地区)的空间范围.研究结果:固碳重要区评价指标体系包括生态系统碳储量、碳汇和固碳潜力3个核心因子,界定过程包括界定范围选择、固碳高值区识别、固碳重要区范围确定和分区命名等步骤.在全国尺度界定了森林、草地两大类共计20个固碳重要区,总面积285.6×104 km2.其中,森林生态系统固碳重要区主要分布在我国东北部、西南部的深山区和东南部的山地丘陵,草地生态系统固碳重要区主要分布在内蒙古高原中东部、新疆西北部山地和青藏高原东南部.固碳重要区面积占全国国土总面积的29.8%,所提供的NPP(净初级生产力)量占全国NPP总量的40.7%,固碳能力是全国平均水平的1.37倍.固碳重要区范围界定结果符合“以较小面积获取较大服务”原则,适于作为我国实现碳减排目标的优先保护区域.      

廊坊市区主要大气污染源排放清单的建立

通过调研、统计廊坊市区工业、城中村及机动车等资料,结合以往清单文献研究结果及清单编制指南中的排放因子,计算了廊坊市区主要大气污染物的排放量,得到廊坊市区2014年主要大气污染源排放清单.结果显示,2014年廊坊市区工业源(固定燃烧)NO_x、SO_2、NMVOC、CO、PM_(10)、PM_(2.5)排放总量分别为6.4×10~3、1.2×10~4、31、1.0×10~4、7.3×10~2、4.4×10~2t,其中热电行业排污贡献率最高,分别占NO_x、SO_2、CO、PM_(10)、PM_(2.5)工业源(固定燃烧)年排放总量的55%、48%、67%、63%、69%;安次区工业企业对气态污染物贡献较高,广阳区及开发区工业企业对颗粒物排污贡献较大.低矮面源(城中村)NO_x、SO_2、NMVOC、CO、PM10、PM_(2.5)年排放总量分别为1.8×10~2、3.6×10~3、3.0、4.9×10~3、1.5×10~2、72 t.道路移动源CO、HC、NO_x、PM_(2.5)年排放总量分别为2.4×10~4、1.9×10~3、2.2×10~3、44 t,其中小型客车对HC和CO贡献率较高,分别为53%和61%;NO_x年排放总量中26%由重型货车贡献;PM_(2.5)则主要由轻型货车和重型货车贡献,占比分别为39%和21%.