Multi-Decadal Changes in Snow Characteristics in Sub-Arctic Sweden

A unique long term, 49-year record (divided into three time periods 1961–1976, 1977–1992, and 1993–2009) of snow profile stratigraphy from the Swedish sub Arctic, was analyzed with a focus on changes in snow characteristics. The data set contained grain size, snow layer hardness, grain compactness, and snow layer dryness, observed every second week during the winter season. The results showed an increase in very hard snow layers, with harder snow in early winter and more moist snow during spring. There was a striking increase in the number of observations with very hard snow at ground level over time. More than twice as many occasions with hard snow at ground level were observed between 1993 and 2009 compared to previous years, which may have a significant effect on plants and animals. The changes in snow characteristics are most likely a result of the increasing temperatures during the start and the end of the snow season.     

Spatial and temporal variations and mobile source emissions of polycyclic aromatic hydrocarbons in Quito, Ecuador

Motor vehicles are a major source of air pollution in Quito, Ecuador; however, little work has been done to characterize spatial and temporal variations in traffic-related pollutants, or to measure pollutants in vehicle emissions. We measured PAH continuously for one year at two residential sites in Quito, and PAH and traffic patterns for one week near a busy roadway. Morning rush-hour traffic and temperature inversions caused daily PAH maxima between 06:00 and 08:00. SO₂, NO_x, CO, and PM_2.5 behaved similarly. At the residential sites PAH levels during inversions were 2-3-fold higher than during the afternoon, and 10-16-fold higher than 02:00-03:00 when levels were lowest. In contrast, at the near-roadway site, PAH concentrations were 3-6-fold higher than at the residential sites, and the effects of inversions were less pronounced. Cars and buses accounted for >95% of PAH at the near-roadway site. Near-roadway PAH concentrations were comparable to other polluted cities.     

A novel four-way combining catalysts for simultaneous removal of exhaust pollutants from diesel engine

A novel four-way combining catalysts containing double layers was applied to simultaneously remove four kinds of exhaust pollutants(NOx,CO,HC and PM) emitted from diesel engine.The four-way catalysts were characterized using scanning electron microscope(SEM) and Ultraviolet visible diffuse reflectance spectroscopy(UV-Vis DRS).Their catalytic performances were evaluated by temperature-programmed reaction technology.The double layer catalysts could effectively remove the four main pollutants.The highest catalytic activity was given by the two-layered catalysts of La0.6K0.4CoO3/Al2O3 and W/HZSM-5.Under the simulated exhaust gases conditions,the peak temperature of the soot combustion was 421°C,the maximal conversion of NO to N2 was 74%,the temperature of the HC total conversion was 357°C,and the maximum conversion ratio of CO was 99%.     

不同土壤层中4种菊酯类农药残留量的测定

采集农田中表层、里层、深层土壤,采用正己烷 ∶ 丙酮＝1 ∶ 1(V/V)作为提取剂^[1,2],土壤样品于Florisil柱中净化,浓缩定容后,用电子捕获检测器检测,石英毛细管柱气相色谱法测定,用外标法定量。以农田表层土壤测定结果为例,甲氰菊酯的回收率为85.2%~102.7%,RSD为2.27%~5.41%;氯氰菊酯的回收率为80.5%~102.7%,RSD为2.84%~6.70%;氰戊菊酯的回收率为80.2%~103.0%,RSD为2.33%~5.95%;溴氰菊酯的回收率为80.8%~102.7%,RSD为2.45%~6.24%。方法简便、快速、成本低。     

Probability and frequency calculations related to protection layers revisited

This article casts a new glance over some methods dedicated to the calculation of the likelihood (probability or frequency) of failure of systems and, in particular, safety-related systems working alone or in association with other protection layers. It consists first in examining with a critical eye the relevancy of the aforementioned methods, which are still often used in spite of their restrictive limitations, and second in proposing an alternative approach for each of them. The correctness of the examinated methods is tested by applying them to very simple systems modeled by fault tree models, with intent to show why these methods are debatable and how they can be replaced by other ones, more appropriate. The particular case of several protection layers having to react on the demand resulting from the global failure of their associated control system is considered. That case leads to revisit the common assumption of the independence between the above protection layers and control system, by taking into account the order of their respective failures from a qualitative and quantitative point of view.     

四川盆地多层逆温特征及其对大气污染的影响

利用2015~2018年探空观测资料以及国家生态环境部发布的环境空气质量监测数据,对四川盆地多层逆温这一特殊的、尚未见详细报道的逆温结构进行了研究,并评估不同逆温类型及垂直结构对大气污染的影响.结果表明：四川盆地多层逆温实际上是一种并不少见的现象,年平均出现频率为20.1%.冬季最为频发,成都冬季高达51.6%.以边界层逆温叠加对流层低层逆温（LTI）的配置为主要特征.依据其垂直结构,划分为四种配置类型,即贴地逆温（SI）叠加脱地逆温（EI）、SI+LTI、EI+LTI、SI+EI+LTI,分别对应第I、Ⅱ、Ⅲ、IV类多层逆温.其中以第Ⅱ、Ⅲ类多层逆温为主.逆温的叠加作用对大气污染的影响更大,多层逆温（特别是第Ⅱ、IV类多层逆温）尤其加大了中度及重度污染出现的可能性.第I、IV类多层逆温对污染物扩散的抑制作用最为明显,其次是第Ⅱ类多层逆温和仅SI（即只出现SI）.第Ⅱ类多层逆温在污染最重的冬季出现频率高、强且厚,叠加抑制作用明显,应是重点关注对象.     

营养失衡下的分层分质EPS对异型膨胀污泥及其沉降性差异影响

为探索EPS对膨胀污泥沉降性的影响,通过减少进水P源、N源的方式培养异型膨胀活性污泥,分析不同层、不同组分EPS对异型膨胀污泥沉降性影响.结果表明：异型膨胀（非丝状菌粘性膨胀、丝状菌膨胀）活性污泥EPS多糖组分Total-PS、中层组分（L-PS）含量均高于正常污泥.非丝状菌粘性膨胀污泥EPS各层多糖含量高于丝状菌膨胀污泥,而各层蛋白质（PN）含量均低于丝状菌膨胀污泥.非丝状菌粘性膨胀污泥Total-EPS（（229±94）mg/g MLSS）、PS/PN值不仅显著高于正常活性污泥（（86±16）mg/g MLSS）,也高于丝状菌膨胀污泥（（108±30）mg/g MLSS）.非丝状菌粘性膨胀污泥EPS多糖总量Total-PS、蛋白质总量Total-PN越高,SVI值越大,污泥沉降性越差,越易膨胀,且EPS蛋白质组分对污泥膨胀作用大于多糖;从不同层EPS看,松散外层（S层）EPS对非丝状菌粘性膨胀作用最大（S-PN与SVI值相关性最大,r为0.881,P<0.05）,是主要影响因子.丝状菌膨胀污泥,除了内层紧密型T-PN对SVI值影响较大外,其他各层、各组分EPS含量与SVI均呈微弱负相关.     

HFL模型在海上压裂工艺过程风险评估中的应用

为有效降低海上压裂工艺过程事故发生的可能性,建立将危险与可操作性研究(HAZOP)、事故树分析(FTA)和保护层分析(LOPA)集成的量化风险评估模型(HFL模型)。阐述HFL模型的集成机理和分析流程。以海上压裂工艺过程高压管线危险性分析为实例,开展该模型的研究与应用。在运用HAZOP方法对危险源初步辨识基础上,构建高压管线超压的蝴蝶结模型(BTM),确定导致事故发生的9种风险因素和5种事故后果,并估算高压管线断裂事故场景的初始事件概率和剩余事故风险。结果表明,现有的独立保护层(IPL)即超压电子保护装置无法使事故风险达到可接受水平,需要通过增加新的IPL,即安装井口保护装置和泄压装置,提高压裂过程高压管线运行的可靠性,确保剩余事故风险处于可接受水平。     

内环境调节层对厌氧生物反应器填埋场中氮转化的影响

为探究内环境调节层对厌氧生物反应器填埋场内环境和氮组分的长效影响,特设矿化垃圾+重质碳酸钙、矿化垃圾+天然沸石这2种内环境调节层分别置入模拟反应器R2和R3中,同时设R1(不含内环境调节层)作为对照,监测分析390 d内固相垃圾和渗滤液中氮组分的变化.结果表明,R1、R2和R3中pH、碱度、氧化还原电位(Eh)、含水率(MS)的大小关系分别为pH(R2)pH(R3)pH(R1)、碱度(R2)碱度(R3)碱度(R1)、Eh(R2)Eh(R3)Eh(R1)、MS(R3)MS(R2)MS(R1).R1、R2和R3中垃圾全氮降解转化率为79.2%、82.3%和88.5%,氨氮为48.3%、60.1%和67.7%,硝态氮为38.5%、44.2%和53.4%;渗滤液中总氮、氨氮和硝态氮的浓度对比分别为TN(R3)TN(R2)TN(R1)、NH_4~+-N(R3)NH_4~+-N(R1)NH_4~+-N(R2)和NO_3~--N(R3)NO_3~--N(R2)NO_3~--N(R1).总体看来,矿化垃圾+重质碳酸钙、矿化垃圾+天然沸石组成的内环境调节层均能长期优化内环境,为氮的降解转化提供有利条件,而矿化垃圾+天然沸石不仅能促进垃圾和渗滤液中氮组分的降解转化,还能一定程度上控制渗滤液循环造成的氨氮累积.     

Estimating High Latitude Carbon Fluxes With Inversions Of Atmospheric CO2

Atmospheric inversions have proven to be useful tools, showing for example the likely existence of a large terrestrial carbon sink in the northern mid-latitudes. However, as we go to smaller spatial scales the uncertainties in the inversions increase rapidly, and the task of finding the distribution of the sink between North America, Europe and Asia has been shown to be very difficult. The uncertainty in the fluxes due to network selection, transport model error and inversion set up tends to be too high for studying either net annual fluxes or interannual variability on spatial scales such as the North American Boreal or Eurasian Boreal regions. We discuss the path forward; to couple together the atmospheric inversions with process based terrestrial carbon models, creating carbon data assimilation systems. Such systems are being developed now and could prove to be very powerful. The multi-disciplinary nature of the data assimilation system requires information from flux towers, soil and above ground biomass inventories, remote sensed fields, atmospheric CO₂ concentrations and climate data as well as model development and will need a massive community effort if it will succeed.