Evaluation of Satellite‐Derived Rainfall Data for Multiple Physio‐Climatic Regions in the Santiago River Basin,Mexico

Assessment of water resources requires reliable rainfall data, and rain gauge networks may not provide adequate spatial representation due to limited point measurements. The Tropical Rainfall Measuring Mission (TRMM) provides rainfall data at global scale, and has been used with good results. However, TRMM data are an indirect measurement of rainfall, and therefore must be validated for its proper use. In this work, a validation scheme was designed and implemented to compare the TRMM Version 7 (V7) monthly rainfall product at different time frames with data measured in two hydrologic subregions of the Santiago River Basin (SRB) in Mexico: Río Alto Santiago and Río Bajo Santiago (RBS). Additionally, three physio‐climatic regions provide an assessment of the interplay of topography, distance from coastal regions, and seasonal weather patterns on the correspondence between both datasets. The TRMM V7 rainfall product exhibited good agreement with the rain gauge data particularly for the RBS and for the whole SRB during wettest summer and autumn seasons. However, strong regional dependence was observed due to differences in climate and topography. Overall, in spite of some noted underestimations, the monthly TRMM V7 rainfall product was found to provide useful information that can be used to complement limited monitoring as is the case of RBS. An improved combined rainfall product could be generated and thus gaining the most benefits from both data sources.     

Inventory and treatment of compost maturation emissions in a municipal solid waste treatment facility

Emissions of volatile organic compounds (VOCs) from the compost maturation building in a municipal solid waste treatment facility were inventoried by solid phase microextraction and gas chromatography–mass spectrometry. A large diversity of chemical classes and compounds were found. The highest concentrations were found for n-butanol, methyl ethyl ketone and limonene (ppm_v level). Also, a range of compounds exceeded their odor threshold evidencing that treatment was needed. Performance of a chemical scrubber followed by two parallel biofilters packed with an advanced packing material and treating an average airflow of 99,300 m³ h^?1 was assessed in the treatment of the VOCs inventoried. Performance of the odor abatement system was evaluated in terms of removal efficiency by comparing inlet and outlet abundances. Outlet concentrations of selected VOCs permitted to identify critical odorants emitted to the atmosphere. In particular, limonene was found as the most critical VOC in the present study. Only six compounds from the odorant group were removed with efficiencies higher than 90%. Low removal efficiencies were found for most of the compounds present in the emission showing a significant relation with their chemical properties (functionality and solubility) and operational parameters (temperature, pH and inlet concentration). Interestingly, benzaldehyde and benzyl alcohol were found to be produced in the treatment system.     

Mapping human vulnerability and risk due to chemical accidents

Chemical accidents in the vicinity of densely populated areas can cause colossal damage. Close proximity of chemical facilities to the general public has been identified as a major issue for increased human exposure in 43% of the accidents investigated by the U.S. Chemical Safety Board (CSB). This emphasises the need for incorporating societal factors in risk assessment to plan actions in order to minimise exposure during accidents. The purpose of this research is to develop a model for the assessment of human vulnerability and risk due to chemical accidents. A GIS based methodology is proposed which uses computer aided hazard modelling tools and technical guidelines to model accidents and assesses population vulnerability. The population vulnerability is determined based on a set of societal indicators derived from relevant research work, expert opinions and suggestions by World Bank. Risk is defined as the probable magnitude of harm to humans and dependent on both the degrees of hazard and vulnerability. A case study is carried out by applying the methodology to Meghnaghat Industrial Area in Bangladesh. Accident scenarios are built and hazard modelling software ALOHA is used to spatially display accident footprints. Vulnerability of population is assessed using data from Bangladesh Bureau of Statistics (BBS) and field survey. The hazard footprints and vulnerability map are superimposed using mapping software ArcGIS to generate a composite risk map. The risk map is used to assess existing land use and recommendations are made for future land use planning. The composite risk map is expected to be of help for effective community response, emergency response planning and allocation of medical and support services during emergencies.     

Key airborne concentrations of chemicals for emergency response planning in HAZMAT road transportation- margin of safety or survival

The release of chemicals due to road transportation accidents could have adverse consequences such as fatality, physical and financial loss and environmental damage. The purpose of this study was to determine the suitable margin of safety/survival of individuals in HAZMAT road transportation accidents for use in Emergency Response Planning (ERP). In this study, at first, the safety margin and survival margin were defined and proposed. Then, as a case study, the chemical tanker trucks in Iran's road transport fleet were investigated and the full bore rupture of the tanker trucks was considered as the selective scenario. Eventually, safety margin and survival margin were determined using ALOHA and PHAST software and the Chemical Exposure Index (CEI). The results showed that using the CEI, among the selected chemicals, ammonia, chlorine and 1,3-butadiene had the highest chemical release potential with the exposure indices of 597, 548 and 284, respectively, and need further investigation. The possible safety margin obtained in this study was distances over 5100 m (using ALOHA software for ammonia) and 10,983 m (using PHAST software for chlorine). On the other hand, the survival margin was distances over 980 m away from the accident area (using ALOHA software for ammonia) and 620 m away from the accident area (using the PHAST software for chlorine). The results of this study indicate that determining the safety and survival margins surrounding the tanker trucks and containers of chemicals is a critical issue for the emergency response planning and determining the standards of road's safety and survival margins. On the other hand, due to the obtainment of different results by various methods and software, in road accidents, the highest hazard distance is suggested to be considered to determine the safety margin (distances longer than 10,983 m) and survival margin (distances longer than 980 m) for ERP, regardless of the type of used material and software.     

Risk assessment of chemical process considering dynamic probability of near misses based on Bayesian theory and event tree analysis

With the development of modern automatic control systems, chemical accidents are of low frequency in most chemical plants, but once an accident happens, it often causes serious consequences. Near-misses are the precursor of accidents. As the process progresses, near misses caused by abnormal fluctuation of process variables may eventually lead to accidents. However, variables that may lead to serious consequences in the production process cannot update the risk in the life cycle of the process by traditional risk assessment methods, which do not pay enough attention to the near misses. Therefore, this paper proposed a new method based on Bayesian theory to dynamically update the probability of key variables associated with process failure risk and obtain the risk change of the near-misses. This article outlines the proposed approach and uses a chemical process of styrene production to demonstrate the application. In this chemical process, the key variables include flow rate, liquid level, pressure and temperature. In order to study the dynamic risk of the chemical process with consideration of near misses, according to the accumulated data of process variables, firstly the abnormal probability of the variables and the failure rate of safety systems associated with the variables were updated with time based on Bayesian theory. On the basis of the dynamic probability of key process variables, an event tree of possible consequences caused by variable anomalies was established. From the logical relationship of the event tree, the probability of different consequences can be obtained. The results show that the proposed risk assessment method based on Bayesian theory can overcome the shortcomings of traditional analysis methods. It shows the dynamic characteristics of the probability of different near misses, and achieves the dynamic risk analysis of chemical process accidents.     

一株茎点霉菌的抗镉机制

从矿区土壤筛选到一株对镉具有较强抗性和富集能力的丝状真菌,编号为F2,根据其形态主要是分生孢子器的特征鉴定为茎点霉菌.对不同镉浓度液体培养下菌体的生长及培养液的pH值变化作了分析,利用扫描电镜、透射电镜与能谱分析相结合的方法研究镉在F2胞内外的沉积作用及分布情况,从而分析该菌对镉的抗性和富集机制.结果表明,100mg/L的镉浓度下,在细胞壁及周围区域存在大量颗粒状镉沉积物,而在菌体表面也有沉淀物附着.因此胞内外沉积作用可能是该菌对高浓度镉的抗性和富集作用的重要途径,而且因为该菌生长过程中尤其是高镉浓度下pH值的大幅度上升,沉积过程可能与该菌在生长过程中产生碱性物质有关.     

螯合沉淀法处理电镀废水的工业实践

介绍了一个采用螯合沉淀法处理电镀废水的典型工业实例。在工业装置上,进行了氢氧化钠、硫化钠和DT-CR去除重金属离子效果的对比,讨论了DTCR的加入量与处理成本的关系和pH值对DTCR用量的影响。结果表明,将废水的pH值调至8.0~8.5后再加DTCR,可以使DTCR的使用量最少,处理成本最低;此法对重金属离子的去除效果远优于传统化学沉淀法。     

高炉煤气洗涤水处理方法的研究

采用化学絮凝法处理高炉煤气洗涤水,通过实验确定了最佳的实验条件和工艺条件。     

20世纪90年代以来上海地区降水资源变化研究

为了揭示20世纪90年代上海地区降水资源的变化特点,根据1991-2003年上海地区11个站降水资料,在与前30年(1961-1990年)平均比较的基础上,统计分析1991年以来降水量、降水日数、相对湿度、蒸发量、降雪日的变化情况,结果表明:20世纪90年代以后,上海地区年平均降水量增加11%,汛期平均雨量增加18%,年平均降水日数却略有减少,这样使年平均降水强度增强了12%,季节分配格局改变,区域分布格局未变;年平均相对湿度和年平均蒸发量略减小,年平均降雪日数减少5d。     

TA对印染废水处理效果的影响

印染综合废水的酸析预处理效率主要受废水中对苯二甲酸（TA）含量的影响,且印染综合废水酸析规律与纯TA配制液相比较存在一定的差异,分别对纯TA配制液,印染综合废水,加TA后的废水,酸析预处理后的废水进行好氧生化处理试验,研究其降解规律与去除效率,结果表明TA属易好氧生化物质,它的存在可提高废水的可生化性。