土壤盐碱化的灾害学定义及其风险评价体系

阐明土壤盐碱化的灾害学概念提出的必要性,并分析土壤盐碱化传统概念在风险评价和其造成的灾害损失评价中的局限性。从深入剖析土壤盐碱化成因出发,以对区域内整体生态环境及社会经济造成损失为判别依据,提出了土壤盐碱化的灾害学定义并论述其概念的内涵与组成。通过与传统土壤盐碱化概念的比较和分析,进一步阐述新概念所具备的进步性和实际应用意义,最后建立了土壤盐碱灾害风险评价体系。     

A Structural Equation Model of Residents＇ Support for Mega Event

The aim of this article is to develop a structural equation model to assess key factors of residents' support for hosting mega event based on previous literature. The model consisted of five latent constructs and eight path hypotheses. A survey was conducted in Shanghai before 2010 World Expo. It was found that the support for mega events is affected directly and/or indirectly by four determinants factors: perceived benefits, perceived costs, personal benefits and community attachment, and support relies heavily on perceived benefits rather than costs. This study contributes to the existing body of knowledge in an attempt to understand local residents' support for a mega event in different economic and cultural settings.     

Short-term physiological responses to a severe acid stress in three macroinvertebrate species: a comparative study

The present study focuses on the sensitivity among freshwater invertebrate species to acidic stress. Three common macroinvertebrate species in the Vosges Mountains (North-Eastern France), Gammarus fossarum (Amphipoda), Hydropsyche pellucidula (Trichoptera) and Dinocras cephalotes (Plecoptera) were exposed for 24, 72 and 120 h to natural acidified water (pH=4.73+/-0.08, [Ca2+]=39.1+/-0.6 micromol l(-1), [Al(tot)]=28.4+/-1 micromol l(-1)). Short-term exposure to acid stress caused significant decreases both in survival rate and haemolymph ions ([Cl-] and [Na+]). The relative sensitivity to a natural acidic stress slightly differed among the species and was in the following order: G. fossarum, as the most sensitive, then H. pellucidula and D. cephalotes. Results of this study confirm the interest of in situ tests to assess the toxicity of short-term acid exposure. Finally, our results reinforce the hypothesis that transient acidification can offset the recovery of sensitive species of macroinvertebrates in streams chemically recovering from acidification either through liming or declining deposition.     

茂名单点系泊系统接卸超巨型油轮的安全论证

通过对30×104t级巨型油轮的吃水深度以及茂名单点系泊缆绳、锚链强度的计算,分析了茂名单点系泊系统接卸30×104t级油轮的安全可靠性.     

Ranking Agricultural Sub-basins for Environmental Protection

Abstract

Reconstructing long-term vegetation buffers along streams in agricultural landscapes has become a common environmental restoration strategy for improving water quality and wildlife habitat connectivity. This article developed a linear weighted model to rank the priority of agricultural sub-basins for the establishment of vegetative buffers. The method was applied to an agricultural watershed of 146 km² in Ontario, Canada. The watershed was divided into 11 sub-basins as basic decision units. In each subbasin, four stream buffer schemes with widths of 5, 10, 15 and 20m were generated. For each buffer, three benefit-cost attributes of reconstructing vegetation cover were estimated, which include acreage per dollar, sediment abatement per dollar and habitat benefit per dollar. These attributes were first normalized using a linear normalization approach to eliminate the effects across different units. The normalized attributes were then integrated using a simple additive weighting method to rank the 11 sub-basins for prioritizing spatial restoration action. A sensitivity analysis was also conducted to observe the impact of a change in attribute weights on the management decisions. The results suggest that vegetation buffers reconstructed for achieving the water quality goal are not effective in improving habitat connectivity and vice versa.     

非饱和黄土土水特征及其强度指标

以多种理论模型对非饱和土三轴仪实测数据进行了拟合评价;并在此基础上,引入非饱和土最新理论,反演和解析了土体脱湿与吸湿条件下的边界土-水特征曲线、渗透系数函数以及吸应力特征曲线;进一步从强度本构入手,结合不同基质吸力的三轴剪切试验结果,探究了基于吸应力的强度特性。研究结果表明:非饱和土三轴仪所测数据点及其三种模型拟合曲线均落在水力边界曲线(SWCC、HCF、SSCC)范围之内,表明了试验结果的正确性和合理性,以及非饱和土中水分的能量和数量的关系因路径差异而具可变性,即基质吸力不再是含水率的单值函数,而是一个范围体系;同时采用吸应力特征曲线的统一有效应力原理来描述土体在非饱和条件下的抗剪强度性质是合理的、普遍有效的,并且验证了土体处于饱和或者无基质吸力时,吸应力不为零,此时的吸应力对应的是土体在剪切破坏时的表观粘聚力这一结论。     

Action de métaux lourds à des doses sublétales sur les caractéristiques de la croissance chez la diatomée Skeletonema costatum

Sublethal effects of mercury, cadmium and copper on the diatom Skeletonema costatum (Grev.) Cleve, grown in batch and bacteria-free culture are studied. Division rate, maximum yield growth, mean cell volume, particulate carbon and nitrogen, and ¹⁴C-bicarbonate uptake are used as toxic impairment criteria. Division rate is the first-affected and most sensitive parameter, but algal responses vary according to the metal. Hg produces an acute decrease in division rate, followed by a temporary recovery of growth capacity within the first 48 h after metal addition. Cd, on the other hand, increases division rate, followed by an obvious decrease. Cu reduces division rate slowly or quickly, depending on the metal concentration. Cell synthesis capacity (culture biovolume, particulate carbon and nitrogen, carbon assimilation) is less affected than division rate, especially with Hg. The C:N cell ratio is unchanged at sublethal concentrations, even when production is reduced. The mean cell volume is slightly affected: the variations are not greater than those of the control during its growth phases. Markedly teratological forms are never observed. In the authors' opinion, these results confirm that many parameters and growth kinetic aspects must be considered to fully appreciate the effects of sublethal concentrations of heavy metals. It would also be of advantage to develop a better methodology for such research, applying, for example, techniques already employed in enzymology.     

Benthic Infaunal Composition and Distribution at an Intertidal Wetland Mudflat

Benthic infaunal communities at Mai Po Inner Deep Bay mudflat, Hong Kong were investigated between August 2002 and August 2003. A total of 55 species belonging to 8 Phyla from more than 99,074 specimens were recorded. The species richness varied between 13 at Station B in August 2002 and 28 at Station D in August 2003 with an average of 21 across the mudflat and the species diversity was low [H′(log₂) = 0.7–3.5 with an average H′ = 2.4]. Seasonal variations were also observed through abundance and biomass across the mudflat among the seasons. The abundance density was between 8,977 individuals m⁻² at Station D in February 2003 and 77,256 individuals m⁻² at Station B in November 2002 and the overall average density was 25,274 individuals m⁻² for the four stations. The benthic infauna were dominated by pollution tolerant species at this wetland mudflat.     

Advanced thermal characterization of fractionated natural organic matter

This work focuses on an experimental investigation of the thermodynamic properties of natural organic matter (NOM), and whether fractions of NOM possess the same thermodynamic characteristics as the whole NOM from which they are derived. Advanced thermal characterization techniques were employed to quantify thermal expansion coefficients (alpha), constant-pressure specific heat capacities (C(p)), and thermal transition temperatures (T(t)) of several aquatic- and terrestrial-derived NOM. For the first time, glass transition behavior is reported for a series of NOM fractions derived from the same whole aquatic or terrestrial source, including humic acid-, fulvic acid-, and carbohydrate-based NOM, and a terrestrial humin. Thermal mechanical analysis (TMA), standard differential scanning calorimetry (DSC), and temperature-modulated differential scanning calorimetry (TMDSC) measurements revealed T(t) ranging from -87 degrees C for a terrestrial carbohydrate fraction to 62 degrees C for the humin fraction. The NOM generally followed a trend of increasing T(t) from carbohydrate to fulvic acid to humic acid to humin, and greater T(t) associated with terrestrial fractions relative to aquatic fractions, similar to that expected for macromolecules possessing greater rigidity and larger molecular weight. Many of the NOM samples also possessed evidence of multiple transitions, similar to beta and alpha transitions of synthetic macromolecules. The presence of multiple transitions in fractionated NOM, however, is not necessarily reflected in whole NOM, suggesting other potential influences in the thermal behavior of the whole NOM relative to fractionated NOM. Temperature-scanning X-ray diffraction studies of each NOM fraction confirmed the amorphous character of each sample through T(t).