钢铁产业政策导向及在环评中应注意的问题

在介绍中国钢铁产业发展现状及其面临形势、中国对钢铁产业进行结构调整的政策导向的基础上,分析了钢铁产业环境影响评价中应注意的若干评价技术要点及评价难点。经分析,因钢铁产业政策的变化,环评的评价技术要点及难点主要为钢铁产业与国家政策的相符性。     

Modeling the Potential Impact of Seasonal and Inactive Multi‐Aquifer Wells on Contaminant Movement to Public Water‐Supply Wells1

Johnson, R.L., B.R. Clark, M.K. Landon, L.J. Kauffman, and S.M. Eberts, 2011. Modeling the Potential Impact of Seasonal and Inactive Multi‐Aquifer Wells on Contaminant Movement to Public Water‐Supply Wells. Journal of the American Water Resources Association (JAWRA) 47(3):588‐596. DOI: 10.1111/j.1752‐1688.2011.00526.x Abstract: Wells screened across multiple aquifers can provide pathways for the movement of surprisingly large volumes of groundwater to confined aquifers used for public water supply (PWS). Using a simple numerical model, we examine the impact of several pumping scenarios on leakage from an unconfined aquifer to a confined aquifer and conclude that a single inactive multi‐aquifer well can contribute nearly 10% of total PWS well flow over a wide range of pumping rates. This leakage can occur even when the multi‐aquifer well is more than a kilometer from the PWS well. The contribution from multi‐aquifer wells may be greater under conditions where seasonal pumping (e.g., irrigation) creates large, widespread downward hydraulic gradients between aquifers. Under those conditions, water can continue to leak down a multi‐aquifer well from an unconfined aquifer to a confined aquifer even when those multi‐aquifer wells are actively pumped. An important implication is that, if an unconfined aquifer is contaminated, multi‐aquifer wells can increase the vulnerability of a confined‐aquifer PWS well.     

Quantifying ecological thresholds from response surfaces

Ecological thresholds are abrupt changes of ecological state. While an ecological threshold is a widely accepted concept, most empirical methods detect them in time or across geographic space. Although useful, these approaches do not quantify the direct drivers of threshold response. Causal understanding of thresholds detected empirically requires their investigation in a multi-factor domain containing the direct drivers (often referred to as state space). Here, we present an approach to quantify thresholds from response surfaces modeled empirically in state space. We present two indices of shape attributes measured from response surfaces. The response surfaces are built using a regression method in state space. The indices are threshold strength (T) and diagonality (D). We use 48 simulated response surfaces of different shapes to test the efficacy of the indices in 3D. Our results show that T is sensitive to the steepness of the transition from one state to the next, with various forms of abrupt, centralized thresholds yielding the highest values among the simulated surfaces. D represents the orientation of the response surface or the simultaneous influence of more than one predictor in eliciting the response gradient. Strongly diagonal surfaces have the most diagonal surface area demonstrated by sharply undulating diagonal surfaces. Given that the success of T and D requires a regression method to accurately capture any shape of complex data structure, we also test the accuracy of empirical regression methods known to be tractable with complex data. We test classification and regression trees (CART), Random Forest, and non-parametric multiplicative regression (NPMR) for binary and continuous responses. We use the 48 simulated response surfaces to test the methods, and we find that prediction accuracy depends on both the T and D of the simulated data for each method. We choose the most accurate method among those we test for capturing any shape of response surface from real data, NPMR. Finally, we use NPMR to build response surfaces and quantify T and D from real ecological data sets. We demonstrate how measuring threshold strength and diagonality from multi-factor response surfaces can advance ecology.     

Engineering layout of fuel tanks in a tank farm

The present paper deals with the location of tanks in a tank farm, in chemical and allied industries. Ideally the tanks are so placed and installed that in case of fire, the neighbouring tanks could remain safe. The safe distance of separation among the tanks is calculated in no wind condition, as well as, in the presence of wind. The paper uses the methods available in literature and modifies the point source model to include the effect of wind vector on the flame height during the calculation of safe inter-tank distance. It is found that for wind velocity > 4 m/s, the modified point source model provides appropriate inter-tank distance. However, for no wind and with wind velocity < 4 m/s, the Shokri-Beyler’s method provides safe inter-tank distance.     

Determining short chain fatty acids in sewage sludge hydrolysate：A comparison of three analytical methods and investigation of sample storage effects

In anaerobic digestion, the production of short-chain fatty acids （SCFAs） can be beneficial or harmful to the overall process, depending on the concentration of accumulated acids. Therefore, the accurate determination of the SCFA concentration in both fresh and stored sludge hydrolysates is important. To select a suitable method for monitoring SCFAs during the anaerobic digestion of sewage sludge, the accuracy of three available analytical methods, including 5 pH point acid titration （TITRA5）, gas chromatography （GC）, and spectrophotometry, were compared in the present study. The results revealed that TITRA5 and GC displayed better agreement in the achieved measurements and higher precision and accuracy than the spectrophotometric assay, as supported by the application of different statistical models. TITRA5 excelled in titrating unfiltered hydrolysate while simultaneously measuring the alkalinity, whereas the GC method provided detailed information on the contribution of different fatty acids to the total acidity. In contrast, the spectrophotometric assay suffered from many forms of interference, depending on the sample＇s matrix. SCFA production followed the pattern of enzymatic reactions and fitted the Michaelis-Menten model. In addition to promoting TITRA5 as an accurate and robust analytical tool for routine SCFA analyses, this comparative study also demonstrated the possibility of storing hydrolysate samples at different temperatures and durations without altering the SCFA measurements.     

钢结构防腐涂层面漆可剥离现象的原因分析及处理措施

目的分析钢结构防腐涂层面漆出现可剥离现象的原因。方法利用质谱仪、环境扫描电镜、ICS 1100型离子色谱仪对涂料和漆膜进行测试分析。结果聚氨酯涂料和漆膜样品含有高沸点溶剂三甲苯和四甲苯,通过微观形貌分析发现漆膜固化不充分,在漆膜样品的萃取溶液中检测出了铵基盐类物质。结论聚氨酯涂料中的高沸点溶剂、低温环境下的小分子胺析出和湿热海洋环境是导致涂层面漆出现大面积可剥离现象的主要原因。     

流域尺度污染溯源模拟-优化防控方法:以铜陵市顺安河流域为例

长江经济带发展是我国重要国家战略,但面临着水环境保护难度大、污染来源不清和措施集成度低等问题.针对流域尺度多源污染协同治理面临的方法瓶颈,结合资料调研分析、机制模型模拟和智能算法优化,构建了"污染精准溯源-措施效果评价-措施整体优化"为主体的流域水环境保护框架,并以安徽省铜陵市顺安河流域为例进行了方案应用.结果表明,新框架可精准量化流域内种植业、农村生活、畜禽养殖、水产养殖、工业废水和生活污水的贡献,并评价多种防控措施及其集成的总体效果;多目标优化蛙跳算法通过系统对比多种方案的成本效益,提供了性价比高的流域多源污染协同治理方案,如通过合理投资可使顺安河流域总氮在丰、平和枯水年分别削减1274.24、855.24和381.96 t ·a^-1,总磷削减321.42、159.80和42.93 t ·a^-1,保障水质达到地表Ⅲ类水质标准.新框架可推广到其他流域,为流域高质量发展背景下的水环境保护提供模式参考.     

基于热爆炸理论的煤燃点确定及动力学分析

为准确判断煤燃点,提高煤自燃灾害防治能力,依据热爆炸理论,结合煤自燃过程放热曲线,将煤自燃升温过程中微分热流曲线上第1处极小值点作为煤的燃点,计算煤着火前后放热过程动力学参数变化.结果表明:随升温速率增加,煤自燃反应放热过程逐渐向高温区域移动,煤燃点逐渐增大,反应的活化能逐渐减小;同一升温速率下燃点之后煤的活化能增大;...     

“Nutrient Inputs to the Laurentian Great Lakes by Source and Watershed Estimated Using SPARROW Watershed Models” by Dale M. Robertson and David A. Saad2

Richards, R. Peter, Ibrahim Alameddine, J. David Allan, David B. Baker, Nathan S. Bosch, Remegio Confesor, Joseph V. DePinto, David M. Dolan, Jeffrey M. Reutter, and Donald Scavia, 2012. Discussion –“Nutrient Inputs to the Laurentian Great Lakes by Source and Watershed Estimated Using SPARROW Watershed Models” by Dale M. Robertson and David A. Saad. Journal of the American Water Resources Association (JAWRA) 1‐10. DOI: 10.1111/jawr.12006 Abstract: Results from the Upper Midwest Major River Basin (MRB3) SPARROW model and underlying Fluxmaster load estimates were compared with detailed data available in the Lake Erie and Ohio River watersheds. Fluxmaster and SPARROW estimates of tributary loads tend to be biased low for total phosphorus and high for total nitrogen. These and other limitations of the application led to an overestimation of the relative contribution of point sources vs. nonpoint sources of phosphorus to eutrophication conditions in Lake Erie, when compared with direct estimates for data‐rich Ohio tributaries. These limitations include the use of a decade‐old reference point (2002), lack of modeling of dissolved phosphorus, lack of inclusion of inputs from the Canadian Lake Erie watersheds and from Lake Huron, and the choice to summarize results for the entire United States Lake Erie watershed, as opposed to the key Western and Central Basin watersheds that drive Lake Erie’s eutrophication processes. Although the MRB3 SPARROW model helps to meet a critical need by modeling unmonitored watersheds and ranking rivers by their estimated relative contributions, we recommend caution in use of the MRB3 SPARRROW model for Lake Erie management, and argue that the management of agricultural nonpoint sources should continue to be the primary focus for the Western and Central Basins of Lake Erie.     

Evaluation of Operational National Weather Service Gridded Flash Flood Guidance over the Arkansas Red River Basin

National Oceanic and Atmospheric Administration's National Weather Service (NWS) flash flood warnings are issued by Weather Forecast Offices and are underpinned by information from the Flash Flood Guidance (FFG) system operated by the River Forecast Centers (RFCs). This study focuses on the quantitative evaluation and limitations of the FFG system using reported flash flood cases in 2010 and 2011. The flash flood reports were obtained from the NWS Storm Event database for the Arkansas‐Red Basin RFC (ABRFC). The current FFG system at the ABRFC provides gridded flash flood guidance (GFFG) system using the NWS Hydrology Laboratory‐Research Distributed Hydrologic Model to translate the upper zone soil moisture to estimates of Soil Conservation Service Curve Numbers. Comparisons of the GFFG and real‐time Multisensor Precipitation Estimator‐derived Quantitative Precipitation Estimate for the same duration and location were used to analyze the success of the system. Typically, the six‐hour duration was characterized by higher probability of detection values than the three‐hour duration, which highlights the difficulty of hydrologic process estimation for shorter time scales. The current system does not take into account physical characteristics such as land use, including irrigated agricultural farm and urban areas, hence, overly dry soil moisture estimates over these areas can lower the success rate of the GFFG product.