旅游灾害事件成灾模型的建立及解析

在我国旅游业蓬勃发展的今天,旅游灾害事件频发已引起了相关部门的高度重视和全社会的关注.根据灾害学原理和对旅游灾害事件成灾机制的研究,建立旅游灾害事件成灾模型,将在成功防范和减轻旅游灾害事件的损失方面发挥巨大作用.该模型主要就旅游灾害事件的基础条件、旅游灾害的诱发因素、旅游灾害的承灾体、旅游灾害损失类型、以及防灾减灾有效措施等方面的问题进行了分析和探讨.     

陕西石泉ML4.9级地震建筑物震害分析

2003年4月24日陕西省石泉县红卫乡一带发生ML4.9级地震.这次地震对石泉、汉阴等县建筑物特别是农村建筑物造成一定程度的破坏,本文统计了不同类型的房屋建筑破坏情况,并对此进行了分析和探讨.     

基于W ebG IS的防震减灾系统研究与设计

开发基于新技术的防震减灾系统以更好地开展大中城市的防震减灾工作是地震工作者亟待解决的重要问题。详细介绍了所开发的基于W ebG IS和人工智能技术的防震减灾信息管理与智能决策支持系统。开发中,以A rcIM S为开发平台,建造了基于GM L(G eography M arkup L anguage)的3层B/S结构(客户端、服务器层、数据库层)的防震减灾W ebG IS体系;采用GM L描述空间数据,构建基于GM L的地理空间数据模型,实现异构数据间的互访;引入A gen t技术,构造出基于多A gen t的智能决策支持系统,通过一系列的A gen t来代替决策支持系统中的功能单元,并以“黑板”为中介,协同A gen t间的工作,以合作求解复杂问题,实现智能化的辅助决策。     

Prediction of zinc, cadmium, lead, and copper availability to wheat in contaminated soils using chemical speciation, diffusive gradients in thin films, extraction, and isotopic dilution techniques

To predict the availability of metals to plants, it is important to understand both solution- and solid-phase processes in the soil, including the kinetics of metal release from its binding agent (ligand and/or particle). The present study examined the speciation and availability of Zn, Cd, Pb, and Cu in a range of well-equilibrated metal-contaminated soils from diverse sources using several techniques as a basis for predicting metal uptake by plants. Wheat (Triticum aestivum L.) was grown in 13 metal-contaminated soils and metal tissue concentrations (Zn, Cd, Pb, and Cu) in plant shoots were compared with total soil metal concentrations, total soluble metal, and free metal activities (pM2+) in soil pore waters, 0.01 M CaCl2-extractable metal concentrations, E values measured by isotope dilution, and effective metal concentrations, C(E), measured by diffusive gradients in thin films (DGT). In the DGT technique, ions are dynamically removed by their diffusion through a gel to a binding resin, while E values represent the isotopically exchangeable (labile) metal pools. Free metal activities (Zn2+, Cd2+, and Pb2+) in soil pore waters were determined using a Donnan dialysis technique. Plant Zn and Cd concentrations were highly related to C(E), while relationships for Zn and Cd with respect to the other measures of metals in the soils were generally lower, except for CaCl2-extractable Cd. These results suggest that the kinetically labile solid-phase pool of metal, which is included in the DGT measurement, played an important role in Zn and Cd uptake by wheat along with the labile metal in soil solution. Plant Pb concentrations were highly related to both soil pore water concentrations and C(E), indicating that supply from the solid phase may not be so important for Pb. Predictions of Cu uptake by wheat from these soils by the various measures of Cu were generally poor, except surprisingly for total Cu.     

Mycorrhizae increase arsenic uptake by the hyperaccumulator Chinese brake fern (Pteris vittata L.)

Chinese brake fern (Pteris vittata L.) is a hyperaccumulator of arsenic (As) that grows naturally on soils in the southern United States. It is reasonable to expect that mycorrhizal symbiosis may be involved in As uptake by this fern. This is because arbuscular mycorrhizal (AM) fungi have a well-documented role in increasing plant phosphorus (P) uptake, P and As have similar chemical properties, and ferns are known to be colonized by AM fungi. We conducted a factorial greenhouse experiment with three levels of As (0, 50, and 100 mg kg(-1)) and P (0, 25, and 50 mg kg(-1)) and with and without Chinese brake fern colonized by a community of AM fungi from an As-contaminated site. We found that the AM fungi not only tolerated As amendment, but their presence increased frond dry mass at the highest As application rate. Furthermore, the AM fungi increased As uptake across a range of P levels, while P uptake was generally increased only when there was no As amendment. These data indicate that AM fungi have an important role in arsenic accumulation by Chinese brake fern. Therefore, to effectively phytoremediate As-contaminated soils, the mycorrhizal status of ferns needs to be taken into account.     

Influence of canola and sunflower diet amendments on cattle feedlot manure

Cattle (Bos taurus) producers can replace a part of the traditional diet of barley (Hordeum vulgare L.) grain/silage with sunflower (Helianthus annus L.) seeds or canola meal (Brassica napus L.)/oil to enhance conjugated linoleic acids (CLA) content in milk and meat for its positive health benefits. The objective of this study is to investigate the effects of feeding sunflower or canola to finishing steers on cattle manure chemical properties and volatile fatty acid (VFA) content. The control diet contained 84% rolled barley and 15% barley silage, which provided only 2.6% lipid. The other six treatments had 6.6 to 8.6% lipid delivered from sources such as hay, sunflower seed (SS), canola meal/oil, and SS forage pellets. Manure samples (a mixture of cattle urine, feces, and woodchip bedding materials) were collected and analyzed after cattle had been on these diets for 113 d. The dietary source and level of lipid had no effect on organic N and nitrate N content in manure, but significantly affected ammonia N and VFA. Inclusion of SS forage pellets, hay, or canola meal/oil in cattle diets had no significant impact on manure characteristics, but SS significantly reduced the pH and increased propionic, isobutyric, and isovaleric content. In addition, N loss after excretion (mainly from urine N) increases with the pH and N levels in both feed and manure. The combination of SS with barley silage resulted in a lower VFA and NH3 content in manure and should be a more attractive option. To better manage N nutrient cycles and reduce NH3 related odor problems, feed and manure pH should be one of the factors to consider when determining feed mix rations.     

White spruce response to co-composted hydrocarbon-contaminated drilling waste: effects of compost age and nitrogen fertilization

There are growing interests to use co-composted drilling wastes contaminated with hydrocarbons as growth media for planting in land reclamation. However, such use of the compost may have potential problems such as inherent toxicity of residual hydrocarbon and microbial N immobilization due to high compost C to N ratios. We investigated the growth, biomass production, N uptake, and foliar delta13C of white spruce (Picea glauca [Moench] Voss) seedlings in a pot experiment using 1-, 2-, 3-, and 4-yr-old composts (with different hydrocarbon concentrations and C to N ratios) and a local noncontaminated soil with (200 kg N ha(-1)) or without N fertilization. Growth and N content of seedlings (particularly N content in roots) were lower when grown in the compost media as compared with those grown in the soil. Within the compost treatments seedling growth was affected by compost age, but the magnitude of growth reduction was not linearly proportional to hydrocarbon concentrations. Plant N uptake increased with compost age, which corresponds with an increase in indigenous mineral N concentration. Effects of N fertilization on N uptake were curtailed by the presence of indigenous mineral N (e.g., in the 4-yr-old compost) and by fertilization-induced stimulation of microbial activities (e.g., in the 1-yr-old compost). The differences in foliar delta13C values between seedlings grown in compost and soil (P < 0.05) suggest that limitations on water uptake caused by the residual hydrocarbon might have been the predominant factor limiting seedling growth in the compost media. This study suggests that water stress caused by residual hydrocarbons may be a critical factor for the successful use of co-composted drilling wastes as a growth medium.     

Analysis of ecotoxic influence of waste from the biomass gasification process

Environmental Science and Pollution Research - The purpose of this research was evaluation of the effect of soil contamination with waste coming from biomass gasification on chosen indicators of...     

Optimal Policy Mechanism Design for Cross-Sector and Multi-Stage Pollution Control with a Bilevel Model: Application to SO<Subscript>2</Subscript> Emission in China

In this paper, we construct a multi-stage coordinated programming model under tax system to control SO₂ emission. The model is based on an explicitly formulated SO₂ abatement cost function created under Chinese condition. Analysis of the effectiveness and impact on the economy of the model is carried out with consideration of game theory. By solving the model, theoretical results show that the volume-based multi-stage SO₂ tax system has two properties: effectiveness and equal-rate. Based on these theoretical results, empirical study is also performed using Chinese historical data. Compared with yearly single-stage programming model, the tax rate generated by the coordinated multi-stage programming model is time-invariant and rather moderate in scale. The total abatement cost among planning years in our model is 21.03 % less than the actual number and 6.68 % less than that in the single-stage situation. The tax payment suggested by our model is 10.62 % less than by the single-stage model. In general, a coordinated multi-stage programming model helps reduce the overall costs of environmental protection while achieving the same emission control target with less burden added to the economy.     

Research status,challenges and future prospects of renewable synthetic fuel catalysts for CO2 photocatalytic reduction conversion

Environmental Science and Pollution Research - In recent years, with global climate change, the utilization of carbon dioxide as a resource has become an important goal of human society to achieve...