激光诱导击穿光谱技术在环境领域中的应用动态

激光诱导击穿光谱技术是一种通过分析物质等离子体发射光谱而获取物质成分和含量的分析技术。近些年,该技术已经成为光谱学领域的研究热点且发展迅速,涌现出多种新的检测手段和仪器。从它的基本原理、发展历史及其在土壤、水和大气等生态环境保护领域的应用情况为基础,分析总结其优点以及所面临的问题和挑战。     

湖南省农业旱灾脆弱性综合分析与定量评价

旱灾是湖南省农业特别是粮食生产可持续发展的严重制约因素。在同一致灾强度下，灾情随灾害脆弱性的增强而加重，降低灾害脆弱性可减轻灾害造成的直接经济损失，因此农业旱灾脆弱性的研究对湖南省减灾和农业可持续发展具有特别重要的意义，湖南省自然生态环境和社会经济状况各异，农业旱灾脆弱性各地不同，选择降水量，蒸发量，水利化程度等9个指标综合评价了各个县市的旱灾脆弱性，并利用GIS技术进行旱灾脆弱性区划，结果表明，湘中衡邵盆地和湘西北山地是农业旱灾严重脆弱带，湖南山地区为强度旱灾脆弱带，沅麻盆地山地区为中度旱灾脆弱带，洞庭湖平原和湘东北山地旱灾脆弱性较小。     

小麦高分子量谷蛋白亚基基因的PCR及AS-PCR标记

选用高分子量麦谷蛋白亚基(HMW-GS)在Glu-D1位点已知的 26个普通小麦品种,包括 15个 (TriticumaestivumL. )川育系列品种及其 11个亲本,根据其亚基Dx5和Dy10基因的特异序列设计引物.通过对Dx5基因的PCR扩增及对Dy10基因的AS-PCR扩增,结果表明,所设计的引物对Dx5和Dy10都能扩增出特异条带,而携有Dx5基因的材料同时也携有Dy10基因.说明用所设计的引物可快速有效的鉴定出普通小麦中是否带有优质的 5 10亚基.图 4参 15     

地铁人员可用疏散时间模拟

人员可用安全疏散时间是衡量公共场所安全性能的重要指标.为了能从定量风险分析的角度考察公共场所的安全疏散性能,引入蒙特卡罗模拟技术.选取天津小白楼地铁系统作为研究对象;建立极限状态方程以刻画地铁人员可用安全疏散时间;最后,通过Matlab提供的M语言编程,实现了蒙特卡罗模拟,得到了与极限状态方程相对应的概率密度函数,累加分布函数和余补累加分布函数.通过余补累加分布函数定量描述了人员在地铁火灾事故中安全逃生的概率.结果表明,蒙特卡罗模拟技术是描述同时具有参数不确定性和模型不确定性的复杂问题的有力工具.     

Study on membrane fouling of submerged membrane bioreactor in treating bathing wastewater

A pilot-scale submerged membrane bioreactor (MBR) was used to treat the bathing wastewater for more than 90 d. Several factors affecting membrane fouling were studied, including the variation in transmembrane pressure (TMP), changes in extracellular polymeric substance (EPS), and distribution of membrane resistance (R). The relationships between R and EPS concentration were found to be R = 0.00008(EPSS)2.915 in the mixed liquor (EPSS) and R = 0.2853(EPSm) - 0.824 on the membrane surface (EPSm). The constant...     

Real-time risk assessment of explosion on offshore platform using Bayesian network and CFD

Combustion or explosion accident resulting from accidental hydrocarbon release poses a severe threat to the offshore platform's operational safety. Much attention has been paid to the risk of an accident occurring over a long period, while the real-time risk that escalates from a primary accident to a serious one was ignored. In this study, a real-time risk assessment model is presented for risk analysis of release accidents, which may escalate into a combustion or explosion. The proposed model takes advantage of Fault Tree-Event Tree (FT-ET) to describe the accident scenario, and Bayesian network (BN) to obtain the initial probability of each consequence and describe the dependencies among safety barriers. Besides, Computational Fluid Dynamics (CFD) is applied to handle the relationship between gas dispersion and time-dependent risk. Ignition probability model that considering potential ignition sources, gas cloud, and time series are also integrated into this framework to explain the likelihood of accident evolution. A case of release accidents on a production platform is used to test the availability and effectiveness of the proposed methodology, which can be adopted for facilities layout optimization and ignition sources control.     

Defining the balance point between conservation and development

In the face of the current global ecological crisis and the threats it poses to human survival and security, the fundamental solution is to resolve the deep contradiction between conservation and economic development. We considered the 3 key and basic questions of why to protect, how much to protect, and where to protect natural areas. Human survival depends on functioning ecosystems and the ecosystem services they provide. In this regard, conserving core biodiversity conservation priority areas (BCPAs) can provide maximum conservation benefit. The goals of protected area (PA) systems globally and nationally must be clearly defined so as to sustain the survival and development of people and to coordinate and balance other objectives with this goal at the center. There is an urgent need to study, calculate, and define the extent of the natural world to ensure the well-being of people. We call this area over which natural areas of land and sea extend across the world or a country nature proportion (N%). Especially, a minimum area that ensures human survival should be protected, and we suggest that this area should cover core BCPAs so that it can achieve the maximum conservation benefit. These recommendations could be applied at global or national levels. The Chinese government proposes “developing a protected-area system composed mainly of national parks,” and it has unified the administration of PAs into a central management authority. At this key time in the reform of the PA system, should this proposal be adopted, conservation will garner the greatest social consensus and support, and planning at the national level for BCPA coverage will be improved. We believe these recommendations are critical for China and other countries and extremely important for the world because they will pave the way toward a balance between nature conservation and human development as the projected human population reaches 10 billion by 2050.     

Detection of dioxygenase genes present in various activated sludge

GOAL, SCOPE AND BACKGROUND: Activated sludge from refineries contains various microorganisms that could utilize aromatics under aerobic conditions due to the oxygenase enzymes. Dioxygenase enzymes are oxygenases, which are involved in the ring cleavage step of aromatic hydrocarbons. In this study, the selected catabolic loci involved in ring cleavage have been monitored in the activated sludge samples at different time intervals. The investigation of the dioxygenase genes in the Effluent Treatment Plants (ETPs) and evaluation of their presence at different time points provides a clue for the aromatic utilizing potential of the inherent microbial flora. METHODS: The catabolic gene loci pheB, xylE, tod-isp, bed and nahG responsible for the enzymes catechol 1,2-dioxygenase, catechol 2,3-dioxygenase, toluene dioxygenase-iron-sulphur protein component, benzene dioxygenase and naphthalene dioxygenase were used respectively. The time dependent change in eubacterial population was demonstrated by the amplification of 16S rDNA product, followed by restriction digestion. The template DNA was obtained from the activated sludge collected from ETPs. The supporting physiological data for the overall performance of sludge was developed using respirometric analysis. The on-site COD and MLSS analysis for ETP was used in final evaluation. The study was carried out with samples collected from three different ETPs and also from a selected ETP at different time intervals. RESULTS AND DISCUSSION: The respirometric studies were carried out with phenol, catechol, toluene, and naphthalene to arrive at the target genotypes for further study by PCR protocol. The respirometric analysis coupled with the COD and MLSS analysis represented the physiological capacity of the various sludges. Initially, the tracking protocol was optimized by using different sludge samples, which were collected from refineries. The selected genotypes were amplified and their presence has been confirmed using Southern analysis. The gene loci tod-isp, bed and xylE were commonly observed at various time intervals of the sludge from the same source. The gene loci pheB and nahG were found to be relatively rare. CONCLUSION: The 16S rDNA PCR products after restriction digestion produced different DNA fingerprint patterns, suggesting that the microbial community composition was diverse in the three sources. Similarly, the presence of the catechol 2,3-dioxygenase, benzene dioxygenase and toluene dioxygenase genes confirmed the aromatic degrading potential in the various sludges. The probes could not pick the nahG and pheB genes. However, the respirometeric assay suggested that the oxidative capacity to use naphthalene as a substrate exists. RECOMMENDATION AND PERSPECTIVE: Our study of the diversity at various time points from the ETP provided an overview of the shifts of the catabolic composition of the sludge. This also depends on the influential parameters like the incoming pollutant level and the environmental conditions that are prevailing and often changing from time to time. The results of direct DNA extraction and PCR amplification do reflect the relative abundance of a particular catabolic genotype, which could be used to monitor the efficiency of treatment.     

基于Tanks 4.0.9d模型的石化储罐VOCs排放定量方法研究

石化储罐VOCs排放是石化行业重要的VOCs排放源之一.为了掌握石化储罐VOCs的排放情况,研究了基于Tanks4.0.9d模型计算各种类型储罐VOCs排放量的方法,并对卧式固定顶罐、立式固定顶罐、内浮顶罐和外浮顶罐的VOCs排放量进行了实例计算.同时,探讨了在国内使用Tanks 4.0.9d模型时需要考虑的所在地气象数据、储罐密封情况、储存物质的参数选择及参数单位换算问题.Tanks 4.0.9d模型可以作为一种方便且准确性较高的石化储罐VOCs排放定量方法在国内推广使用.     

平寨水库荧光溶解性有机质的来源、特征及其动态转化

利用三维激发发射矩阵光谱(3-D EEM)和平行因子分析,研究了三岔河流域平寨水库溶解有机质的来源、组成和转化情况。在平寨水库的入库水、表层水(0～5 m)、深层水(10～60 m)和出库水中,检测到了几种荧光溶解有机质组分,分别为陆源类腐殖质、自源类腐殖质和浮游植物源的类蛋白质(或类色氨酸或类酪氨酸)。陆源类腐殖质的荧光强度在入库水中略高于出库水,表明陆源类腐殖质在水库系统中相对稳定,大坝截流对其影响不大。自源类腐殖质的荧光强度在库区明显高于入库水和出库水,表明自源类腐殖质既由自源有机物分解产生,又在光化学、微生物和大坝物理拦截过程的影响下发生分解;其他荧光组分中也检测到相似的结果。水温、pH、溶解氧和有色溶解有机质表现出相似的季节变化,光化学和微生物以及大坝拦截是引起水库入库水、库区表层水、库区深层水和出库水中荧光溶解有机质时空动态变化的主要原因。