陕西省2000年天气气候异常变化与自然灾害

分析陕西省2000年天气气候变化发现,隆冬降雪明显增多,春旱异常严重,秋霖明显,沙尘暴天气明显增加,这是多年来未曾见到的现象。异常的天气气候使得多种自然灾害并发。     

1—硝基芘对斜生栅藻的毒性研究

酿要用评价化学品对藻类毒性的标准实验方法,研究了１－硝基芘对斜生栅藻生长的影响,得到了１－ＮＰ抑制斜生栅藻生长的ＥＣ５０（９６ｈ）为０．１８２４ｍｇ．１＾－１,实验结果还表明,１－ＮＰ对藻生长的抑制作用随时间的延长而增加,抑制物性表现为特久且强度大,抑制机理为不可逆性抑制。     

Research on the alternatives in a strategic environmental assessment based on the extension theory

The main purpose of a strategic environmental assessment (SEA) is to facilitate the early consideration of potential environmental impacts in decision-making processes. SEA alternative identification is a core issue within the SEA framework. However, the current methods of SEA alternative formulation and selection are constrained by the limited setting range and lack of scientific evaluation. Thus, the current paper attempts to provide a new methodology based on the extension theory to identify a range of alternatives and screen the best one. Extension planning is applied to formulate a set of alternatives that satisfy the reasonable interests of the stakeholders. Extension priority evaluation is used to assess and optimize the alternatives and present a scientific methodology for the SEA alternative study. Thereafter, the urban traffic plan of Dalian City is used as an example to demonstrate the feasibility of the new method. The traffic planning scheme and the environmental protection scheme are organically combined based on the extension theory, and the reliability and practicality of this approach are examined.     

Characteristics of atmospheric carbonyls and VOCs in Forest Park in South China

The diurnal variation of atmospheric carbonyls and VOCs in a forest in south China were studied in summer 2004. Twenty kinds of carbonyls and eight kinds of VOCs were identified and quantified. Formaldehyde and acetaldehyde were the two most abundant carbonyls, while the most abundant VOCs were isoprene, followed by o-xylene. Most C₃-C₁₀ carbonyls had higher concentrations from 09:00 to 15:00, and their levels were lower during night-time and often reached the lowest in early morning. Formaldehyde and acetaldehyde, however, showed two high levels in their diurnal patterns partly due to their different sources and sinks. The VOCs had different diurnal patterns compared to most carbonyls. The highest concentrations were observed from 03:00 to 06:00 for 1-butene, from 06:00 to 12:00 for isoprene, and from 12:00 to 15:00 for α-pinene. The highest levels for aromatic hydrocarbons occurred during midnight and the lowest in late afternoon. According to the study, emissions from vegetation and photo-oxidation of gas-phase hydrocarbons were the main sources for some carbonyls and VOCs in this region. Other compounds, such as formaldehyde, acetaldehyde and BTEX, showed anthropogenic sources.     

Chemical dynamics of the Sava riverine system

Presented here is a study of the geochemical dynamics of the entire River Sava watershed, a major tributary of the River Danube which has not previously been investigated. The sampling was performed at 33 selected locations along the main channel of the stream and at its largest tributaries during three sampling seasons (fall 2005, spring 2006 and fall 2006), going from headwater locations to the mouth near the confluence with the Danube. Almost 80% of the solutes are derived from carbonate mineral weathering and represent over 50% of specific HCO(3)(-) flux normalized to unit basin area at the mouth of the Danube. Statistical analysis indicates that agricultural and industrial sources contribute significantly to increased Na(+), K(+), Cl(-), SO(4)(2-) and NO(3)(-) concentrations in tributary waters. Different processes control the water chemistry along the course of the Sava's drainage-the upper reaches are largely regulated by contributions from carbonate mineral weathering, the middle reaches are influenced by agricultural activity and biological processes related to eutrophication, while the lower reaches tend to have more pronounced parameters related to the industrial processing along with leakages from municipal sanitary systems of these higher population density areas.     

Application of response surface methodology to the treatment landfill leachate in a three-dimensional electrochemical reactor

The influence of different variables on the removal of ammonia nitrogen and COD from landfill leachate was investigated in a three-dimensional electrochemical reactor. Box–Behnken statistical experiment design and the response surface methodology were used to investigate operating condition effects, such as current density, activated carbon to water ratio and the reaction time, on ammonia nitrogen removal efficiency and COD removal efficiency. The positive and negative effects of variables and the interaction between variables on ammonia nitrogen removal and COD removal were determined. The response surface methodology models were derived based on the results and the response surface plots were developed accordingly.     

Simulation of substrate degradation in composting of sewage sludge

To simulate the substrate degradation kinetics of the composting process, this paper develops a mathematical model with a first-order reaction assumption and heat/mass balance equations. A pilot-scale composting test with a mixture of sewage sludge and wheat straw was conducted in an insulated reactor. The BVS (biodegradable volatile solids) degradation process, matrix mass, MC (moisture content), DM (dry matter) and VS (volatile solid) were simulated numerically by the model and experimental data. The numerical simulation offered a method for simulating k (the first-order rate constant) and estimating k₂₀ (the first-order rate constant at 20 °C). After comparison with experimental values, the relative error of the simulation value of the mass of the compost at maturity was 0.22%, MC 2.9%, DM 4.9% and VS 5.2%, which mean that the simulation is a good fit. The k of sewage sludge was simulated, and k₂₀, k_20s (first-order rate coefficient of slow fraction of BVS at 20 °C) of the sewage sludge were estimated as 0.082 and 0.015 d^?1, respectively.     

绵竹县社会经济发展战略的系统动力学研究

摆脱传统思维方式的束缚,采用科学的、系统的、程序化的方法制定我国县级经济和社会发展战略,是我国现代化建设提出的一项艰巨任务。本文旨在通过介绍“绵竹县经济社会发展总体规划(系统工程应用)研究”的核心部分——绵竹县社会经济系统动态仿真模型设计与发展战略的仿真实验择优,阐述系统工程的原理和运用数学模型方法对县级社会经济系统进行总体设计、预演和优化的一点体会。