沿海砼结构耐久性问题研究现状与对策

混凝土耐久性能不良引起的适用性、安全性问题以及由此引发的环境、能源、经济问题在全球范围内已引起广泛的关注.而沿海城市经济的飞速发展和大规模的开发海洋资源使得混凝土结构面临严峻的海洋环境的挑战.因此,了解沿海混凝土结构耐久性问题的研究现状与对策具有十分重要的现实意义.综合分析了沿海砼结构性能退化的原因及解决办法并在此基础上指出进一步研究的可能方向.     

城乡一体化发展下的土地整治规划环境影响评价——以山东省诸城市为例

土地整治环境影响评价是土地整治规划编制过程中的一个重要环节,目前的土地整治环境影响评价多是从某方面评价土地整治规划对环境的影响。在城乡一体化发展的背景下,按照"全域规划、全域整治"的要求,通过识别土地整治规划对经济、社会和环境影响,建立评价指标体系,以山东省诸城市为例,对土地整治规划环境影响进行综合评价。     

陕北黄土丘陵沟壑区农户气候变化的适应行为及影响因素分析

从农户个体微观视角,研究农业的活动主体--农户的气候变化适应行为。选择陕北黄土丘陵沟壑区,采用问卷调查和半结构式访谈相结合的方法研究农户气候变化感知与适应行为,运用二元逻辑回归模型分析影响该地区农户适应行为的因素。结果表明：农户对气候变化趋势感知比较一致,认为近5 年夏季和冬季气温升高,降水减少,但与实际观测存在一定偏差。农户应对气候变化采取适应行为的比重并不高,只有57.8% 的农户表示采取了相应的措施来应对气候变化。农户适应行为受气候变化感知的影响,此外,家庭社会经济属性对农户采取适应行为的概率影响显著,而性别、年龄、文化程度等人口属性因素与农户采取适应行为的概率关系不大。     

基于RS和GIS的松辽平原黑土流失研究

基于RS和GIS技术,利用1986年TM数据和2001年ETM数据,对松辽平原黑土分布现状与动态变化进行监测研究,分析了黑土流失特点及其时空分布规律,并引入冲沟线密度概念量化黑土流失趋势。结果表明:松辽平原典型黑土面积54 989.92 km2,沿京哈铁路线呈弧形条带状展布;1986~2001年间,黑土区水土流失面积达3 765.21 km2,减少速度为251.01 km2/a,集中在河流两岸、较大建筑用地附近和与盐碱土接壤的地区;仅考虑冲沟的有效作用域,预计到2016年黑土面积平均会有1411.0 km2/a转变为冲沟,黑土流失状况不容乐观。     

黄土高原沟壑区干旱阳坡的地域分异特征

针对黄土高原沟壑区干旱阳坡这种典型的困难立地进行因地制宜的植被恢复建设。本文选取甘肃西峰、山西吉县、陕西安塞、宁夏固原为研究区,采用25 m分辨率的DEM为数据源,基于GIS提取相关地形信息研究其干旱阳坡的地域分异特征。结果表明：①不同类型沟壑区干旱阳坡面积比例占45%～54%,表现为高塬沟壑区＞过渡地带＞丘陵沟壑区。②不同类型沟壑区干旱阳坡面积比例随坡度的变化规律不同,高塬沟壑区呈左偏态分布,其他样区均基本呈近似正态分布,且丘五区和过渡地带呈双峰现象。③不同类型沟壑区梁峁坡面积比例关系为：高塬沟壑区>过渡地带>丘陵沟壑区;沟坡面积比例为：丘陵沟壑区>过渡地带>高塬沟壑区;川台地面积比例为：丘五区＞过渡地带＞丘二区＞高塬沟壑。④不同类型沟壑区各立地类型组所占的面积比例各不相同,除高塬沟壑区外基本呈阳向缓坡组＞阳向陡险坡组＞坡顶或沟底。研究成果可为黄土高原地区开展抗旱造林与植被重建提供理论依据。     

雍家沟泥石流活动特征与堵江

自2008年汶川地震以来,四川省绵竹市清平乡雍家沟已暴发过多场泥石流,造成了严重的堵断公路和堵塞河流事件,其中,2012年“8·18”暴发的泥石流规模最大,造成绵远河全部堵塞.通过分析2010年“8·13”与2012年“8· 18”两场泥石流的降雨过程发现,雍家沟暴发泥石流的前期累积雨量在增加,激发雨强在降低.2008年汶川地震导致雍家沟的主沟和支沟内堆积了大量的松散固体物质.野外调查发现,雍家沟多次暴发泥石流的活动路径并不一致,其中,2012年“8· 18”泥石流主要沿1号支沟活动,沟道的侵蚀宽度随着与主沟沟口距离的增加而变窄,沟道内剩余堆积体厚度随着距离的增加呈现先增后减的规律,且沟道内的物质粒径分布具有随机性.对雍家沟在不同暴雨频率下暴发泥石流可能引起的堵江情况进行了分析,结果表明,在暴雨频率大于20％的情况下暴发泥石流便可造成堵江事件,甚至可将主河全部堵塞.     

Hydrochemical characterization of an acid mine drainage-affected reservoir: the Sancho Reservoir,Huelva, southwest Spain

Abstract

The objectives of this study were to discover the relationship between variables in a water reservoir and the hydrochemical variations related to acid mine drainage (AMD), and to describe the horizontal stratification related to vertical salinity and variations in metals present in the region. The information obtained may be used for establishing risk evaluation criteria and to design future remediation strategies, which could be useful for new dams. The hydrochemical characterization was based on a sampling campaign performed in October 2011. A total of 28 samples, at 1-m-deep intervals, were obtained. The hydrogeochemical study of the polluted reservoir shows that the dilution effect is not sufficient to neutralize AMD contributions from mining activity. Sampling carried out from the surface water to the deepest points reveals stratification of the reservoir that allows it to be included in the group of monomictic and holomitic lakes.

Editor D. Koutsoyiannis; Associate editor M.D. Fidelibus     

Modeling the Permeability Loss of Metallic Iron Water Filtration Systems

Over the past 30 years the literature has burgeoned with in situ approaches for groundwater remediation. Of the methods currently available, the use of metallic iron (Fe⁰) in permeable reactive barrier (PRB) systems is one of the most commonly applied. Despite such interest, an increasing amount of experimental and field observations have reported inconsistent Fe⁰ barrier operation compared to contemporary theory. In the current work, a critical review of the physical chemistry of aqueous Fe⁰ corrosion in porous media is presented. Subsequent implications for the design of Fe⁰ filtration systems are modeled. The results suggest that: (i) for the pH range of natural waters (>4.5), the high volumetric expansion of Fe⁰ during oxidation and precipitation dictates that Fe⁰ should be mixed with a non‐expansive material; (ii) naturally occurring solute precipitates have a negligible impact on permeability loss compared to Fe⁰ expansive corrosion; and (iii) the proliferation of H₂ metabolizing bacteria may contribute to alleviate permeability loss. As a consequence, it is suggested that more emphasis must be placed on future work with regard to considering the Fe⁰ PRB system as a physical (size‐exclusion) water filter device.     

Modeling the morphology of gully cross sections in the Yuanmou Dry-hot Valley

Abstract

Characterizing gully cross sections (GCs) is essential for calculating the volume and erosion rate of the gully. However, little research has focused on modeling the morphology of GCs. This study investigated 456 GCs with a laser distance meter located at the mouth, middle, and head of 152 gullies in the Yuanmou Dry-hot Valley of China; mapped them with AutoCAD software; fitted them with 2nd–6th degree polynomial functions, and discussed the correlation between the coefficients and the morphology of GCs. The results showed that: (1) using a 2nd-degree polynomial function (y = ax² + bx + c) to describe the morphology of GCs produced a better result than other polynomial functions; (2) the coefficient a of 2nd-degree polynomial function was correlated with depth (r = ?0.226, p < 0.01), gradient (r = 0.545, p < 0.01), and activities; and (3) the symmetry axis (?b/2a) of 2nd-degree polynomial function increased with gully change from left-deflection to right-skewed, and the absolute value showed the asymmetrical degree (r = 0.216, p < 0.01). This study will not only help to understand the morphology and evolution of gullies, but will also provide a scientific basis for prevention of gully erosion.     

济南市土壤重金属污染现状及其土壤生物学表征

以济南市区及郊区农田土壤为对象,研究土壤中重金属污染的特征,结果表明,土壤重金属污染不仅引起了生态环境的恶化,而且影响土壤生物多样性,降低了土壤活性。济南市土壤动物各类群的数量与土壤重金属元素含量的相关性统计结果显示:土壤原生动物数量与Co、Ni含量呈明显负相关;土壤线虫数量与Cu、Mo含量呈显著负相关;旱生土壤动物数量与Cu含量呈显著负相关;说明重金属元素对土壤动物多样性具有不利影响,土壤线虫是耐污种类,旱生动物多为不耐污种类,土壤线虫与旱生动物密度之比可以作为土壤重金属污染程度的生物学指标。通过对土壤地球化学元素含量与土壤生物学参数的相关性分析,找到了重金属的敏感生物指标:Pb污染的生物学指标为土壤线虫;As污染的生物学指标是真菌PLFA含量等,用土壤生物作为敏感、快速的重金属污染生物毒性的指示物,具有广阔的应用前景。