移殖“标准化”背角无齿蚌监测五里湖重金属污染

移殖生物因子相同、遗传质量稳定和污染本底值低的“标准化”背角无齿蚌至太湖五里湖,并以仍养殖在未受污染的中国水产科学研究院淡水渔业研究中心南泉基地的同批蚌作为对照,每3个月回收蚌样,应用电感耦合等离子质谱仪(ICP-MS)研究了重金属Al、Cr、Mn、Fe、Co、Ni、Cu、Zn、As、Mo、Ag、Cd、Ba、Tl和Pb的含量变化.结果表明,“标准化”背角无齿蚌对重金属的积累与特定的季节/时间密切相关,在夏季的含量明显低于春季.移殖五里湖3个月蚌样中Mo和Tl的含量显著高于相应的对照组(P<0.05),而前者Ba的含量显著低于后者(P<0.05).移殖五里湖6个月蚌样中As的含量显著低于对照组(P<0.05).综合重金属污染指数(MPI)和我国及国际上的相关限量标准评价显示,五里湖和南泉基地水体中重金属的含量处于相同水平,重金属污染均不明显.     

Vegetation dynamics in succession process from Stipa bungeana to Artemisia ordosica in the Ordos Plateau北大核心CSCD

Shrub invasion has a serious effect on the structure and function of grassland ecosystems and understanding vegetation dynamics is of great significance to control shrub invasion and recover shrub invaded grassland. In the Ordos Plateau, we selected representative communities in transition process from Stipa bungeana to Artemisia ordosica. By sampling, cutting, and root-drilling methods, plant coverage, density, biomass, litter, root, and species diversity of different communities were investigated and analyzed. The results showed the following: (1) the succession process had six vegetation types, S. bungeana communities, S. bungeana + Cleistogenes squarrosa communities, S. bungeana + Artemisia ordosica communities, A. ordosica + C. squarrosa communities, A. ordosica + Lespedeza davurica communities, and A. ordosica communities. (2) The community coverage decreased initially, and then increased. Whereas, the total density decreased initially, then increased, and then decreased. The aboveground, underground, and total biomasses, and the dry weight of litter showed an increasing trend. (3) The coverage, density, and biomass of S. bungeana decreased gradually, whereas A. ordosica showed an opposite trend. (4) With the increase in soil depth, the dry weight of root showed a decreasing trend. The roots were mainly distributed in the 0-30 cm soil layer. At VI stage, the root distribution of Artemisia community initially increased, and then decreased, and the root depth reached 80-90 cm. (5) The species richness, Simpson, Shannon-Winner, and Pielou evenness indexes initially increased, and then decreased. In summary, shrub encroachment is severe in the Ordos Plateau. Although the community coverage, biomass, and biodiversity during the moderate shrub encroachment stage were high, the shrub-invaded grassland should be restored to S. bungeana grassland due to the decreased grazing value of grassland after shrub invasion. Keywords. © 2018 Science Press. All rights reserved.     

永久基本农田保护的实施评价与政策启示--以我国东部地区XX地级市为例

基于“三调”数据分析我国东部地区XX地级市永久基本农田保护变化,从流失去向与流失空间分布两个方面深入分析了其真实境况,从而提出切实的保护政策建议。结果表明:①流失去向包括农业结构调整、建设占用和自然损毁,其中农业结构调整占用为主导。②城市圈内比圈外占用普遍严重,尤其是城乡建设占用了大量基本农田。③永久基本农田存在空间错配现象,未做到“应划尽划”。据此,提出构建农户补偿机制、县级保护任务量与存量建设指标相挂钩、协同基本农田—生态—城镇空间布局,实施圈内基本农田动态监测机制等系列措施,以提升保护效果。     

关于三峡工程的安全管理

三峡工程举世瞩目，搞好三峡工程的安全管理，对保障参建人员的生命安全和身体健康、促进三峡工程的文明施工、树立三峡工程一流的建设形象具有重要意义。本文在分析三峡工程安全管理现状及特点的基础上，指出切实执行国家对工程施工安全与卫生状况的直接监察、加大工程监理对施工现场安全与卫生状况的监督管理力度与加强三峡工程安全文化建设、提高参建人员安全素质相结合，是实现一流的安全管理的重要保证。     

若尔盖高原可持续发展制约因素浅析

若尔盖谪原包括四川省境内黄河流域区的全部范围，与相邻的甘肃省玛曲沼泽湿地共同成为黄河重要水源涵养地。本文从自然、经济、社会及政策等方面，对若尔盖高原可持续发展的制约因素加以分析，并提出了一些对策和建议。     

地形和土地利用对黄土丘陵沟壑区表层土壤有机碳空间分布影响

研究地形和土地利用类型共同作用下表层土壤有机碳空间分布特征,对准确评估区域土壤有机碳的空间分布和变异特征具有重要意义。以黄土丘陵沟壑区燕沟流域3种地形部位(峁顶、峁坡、沟底)和8种土地利用类型(农田、果园、天然与人工草地、天然与人工灌木林、天然与人工乔木林)为研究对象,采集表层(0~20 cm)314个土壤样品用于研究地形和土地利用方式对黄土丘陵沟壑区小流域表层土壤有机碳空间分布的影响。地形和土地利用方式极显著(P0.000 1)影响小流域表层土壤有机碳含量与分布,并且交互作用显著(P=0.051 1)。地形影响下,土壤有机碳空间分布表现为沟底峁坡峁顶的变化趋势,土壤有机碳含量沟底(8.0 g/kg)、峁坡(7.1 g/kg)分别是峁顶(4.2 g/kg)的1.9、1.7倍。土地利用方式影响下,土壤有机碳空间分布表现为天然乔木天然灌木人工乔木天然草地人工灌木人工草地农田果园的分布变化规律。地形和土地利用交互作用下,农田、果园、天然草地在坡面水土流失条件下显示出土壤有机碳在沟底逐渐富集的特征,沟底有机碳含量农田(6.9 g/kg)、果园(8.8 g/kg)、天然草地(9.3 g/kg)分别是峁顶的1.9、2.0、1.9倍。林地(灌木林和乔木林)却表现为峁坡土壤有机碳含量远远高于沟底,天然乔木林且达到了显著水平,天然乔木峁坡土壤有机碳含量(24.6 g/kg)是沟底(16.4 g/kg)的1.5倍。     

Infiltration characteristics of non-aqueous phase liquids in undisturbed loessal soil cores

The widespread contamination of soils and aquifers by non-aqueous phase liquids (NAPL), such as crude oil, poses serious environmental and health hazards globally. Understanding the infiltration characteristics of NAPL in soil is crucial in mitigating or remediating soil contamination. The infiltration characteristics of crude and diesel oils into undisturbed loessal soil cores, collected in polymethyl methacrylate cylindrical columns, were investigated under a constant fluid head (3 cm) of either crude oil or diesel oil. The infiltration rate of both crude and diesel oils decreased exponentially as wetting depth increased with time. Soil core size and bulk density both had significant effects on NAPL infiltration through the undisturbed soil cores; a smaller core size or a greater bulk density could reduce oil penetration to depth. Compacting soil in areas susceptible to oil spills may be an effective stratage to reduce contamination. The infiltration of NAPL into soil cores was spatially anisotropic and heterogeneous, thus recording the data at four points on the soil core is a good stratage to improve the accuracy of experimental results. Our results revealed that crude and diesel oils, rather than their components, have a practical value for remediation of contaminated loessal soils.     

青藏高原清水河流域水化学特征分析

在野外实地调查的基础上,利用地球物理勘探、水化学分析等技术方法,对青藏高原融冻期内清水河源头上升泉的成因及清水河水化学类型进行了研究,初步探索了清水河流域河流、湖泊水化学特征的变化趋势。结果表明:清水河从源头至清水湖出口段河水的水化学类型由HCO3.Cl-Na.Ca型过渡为Cl.SO4-Na.Mg型;清水河中游的清水湖水化学类型为硫酸钠亚型,没有碳酸盐类型的水化学特征存在,表明清水湖正处于盐化浓缩阶段。     

青藏高原冰川雪坑中离子浓度的区域特征及来源分析

研究了青藏高原古仁河口冰川、小冬克玛底冰川和玉珠峰冰川中的离子浓度特征. 使用离子色谱对这3条冰川雪坑中的样品进行了分析,并运用相关分析法探讨了离子的主要来源. 结果表明,Ca²⁺、Mg²⁺、Na⁺、Cl^-和SO^2-₄的浓度从古仁河口冰川、小冬克玛底冰川到玉珠峰冰川依次升高,即从高原南部到北部依次升高. 反映了从青藏高原的南部到北部,陆源物质成分所占比重越来越大的特征. 玉珠峰冰川中Cl^-、Na⁺和SO^2-₄浓度比古仁河口冰川和小冬克玛底冰川高几倍,可能是由于玉珠峰冰川北侧柴达木盆地盐湖的蒸发及盐类矿物风化的结果. NO^-₃、K⁺ 和NH⁺₄的来源比较复杂,对环境的指示意义不够显著.     

重大突发事件应急管理的新思考——以“4.20”雅安地震为例

为了减少重大突发事件造成的损失,以"4.20"雅安地震为例,分析了重大突发事件具有突发性强、影响范围大且后果严重、救援紧迫性强、参与主体多元化等特点。与汶川地震比较,雅安地震在救灾反应速度、救灾手段和救灾效率3个方面有比较大的进步,但也存在管理混乱、信息混乱、角色混乱等问题。在此基础上,阐述了面对重大突发事件时值得人们思考的问题,为类似事件应急管理提供参考与思路。