单次降水对高寒草地温室气体通量昼夜变化的影响研究

在全球变化背景下,青藏高原降水格局发生改变,并影响高寒草地温室气体排放.为了更好地认识降水变化与高寒草地温室气体排放的关系,在2015年7月24日,通过人工降水6.7 mm,研究了单次降水对高寒草地温室气体昼夜变化的影响.表明:(1)单次降水没有改变土壤温度,但显著增加了土壤湿度;(2)单次降水后24小时内,高寒草地CH4吸收量降低了2.46倍,CO2和N2 O排放量分别提高15.3%和98.9%;(3)单次降水弱化了高寒草地CH4和N2 O排放量与土壤温度的关系.     

Mobility of acid-treated carbon nanotubes in water-saturated porous media

The production, use, and disposal of nanomaterials may inevitably lead to their appearance in water. With the development of new industries around nanomaterials, it seems necessary to be concerned about the transport of nanomaterials in the environment. In this paper, the transport of acid-treated carbon nanotubes (CNTs) in porous media was investigated. Before the mobility investigation, the stability of acid-treated CNT dispersions was studied using ultraviolet-visible spectra and it was indicated that, under the chemical conditions employed in this work, there was no apparent aggregation. The mobility investigation showed that transport of acid-treated CNTs increased with treatment time due to increase in particle zeta potential. Carbon nanotubes treated with nitric acid for 2, 6, and 12 h possessed measured zeta potentials of -30.0, -43.0, and -48.5 mV, respectively. Utilizing clean-bed filtration theory, we showed that acid-treated CNTs have the potential to migrate 3.28, 5.67, and 7.69 m in saturated glass beads, respectively. We showed that solution ionic strength and pH have important effects on the mobility of acid-treated CNTs. Increasing the pH from 6.0 to 7.9 resulted in an increase in migration potential from 2.96 to 10.86 m. Increasing the ionic strength from 0.005 to 0.020 M resulted in a decrease in CNT migration potential from 5.67 to 1.42 m.     

Levels, distribution, and health risk of phthalate esters in urban soils of Beijing, China

The content of phthalate esters (PAEs) was investigated in urban soil samples ( = 127, 0-20 cm) collected from a business area (BU), classical garden (CL), culture and educational area (CU), large public green space (LA), residential area (RE), and roadside area (RO) in Beijing. The sum of all PAE contents ranged from 1.9 to 3141.7 ng/g, with an average of 1139.6 ± 727.6 ng/g. Di-n-butyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP) were the major contaminants in the soil samples. The content of DEHP and DBP in the urban soil of Beijing showed decreasing trends from the center of the city to the suburbs, which was probably because the center of the city has a longer history. In addition, higher DBP content also occurred in the south of the city, which was caused by the existence of several factories that produce commodity chemical and building materials in these areas. Because of its greater age, less disturbance from human activity, and high levels of total organic carbon and black carbon in CL, PAE content in CL was the highest among the six types of land use, followed by RE, CU, BU, LA, and RO. Although in 82.6% of the soil samples, DBP content exceeded the recommended allowable soil content in New York, USA, health risk assessment with CalTOX and Monte Carlo analysis showed that the total cancer risk values of PAEs were lower than the acceptable cancer risk value (10(-4)) and that the risk mainly came from dermal uptake and inhalation exposure pathways.     

Lake area changes in the middle Yangtze region of China over the 20th century

The Jianghan Plain and the Dongting lake area, located in the middle reaches of the Yangtze River are famous for their abundant freshwater lakes. The lakes have undergone changes in size and number over thousands of years due to natural causes and human activities. The 20th century particularly, witnessed dramatic changes in the freshwater resources of this region. This paper traces and analyzes lake evolution in the middle reaches of the Yangtze River over the past century. Lakes greater than 0.1 km(2) in size are mapped using Geographic Information System. Data is acquired and integrated from drainage network maps, relief maps, historical maps and remotely sensed images for different time periods. The results indicate that while there has been little change in the number of lakes over the past century, the lake area has experienced a dramatic decrease of 58.06%. The paper also examines the natural processes and human activities that may have contributed to the decrease in lake area. The results show that the decrease in total lake area appears to coincide with periods of rapid land reclamation in the middle reaches of the Yangtze River. Moreover, uncontrolled land reclamation activities can create an increase in sediment deposition in lakes thereby further reducing the lake size. Reduction of the lake area directly affects flood-control and has a negative ecological impact on the environment and on human life and property.     

火灾损失特性研究

基于物质的热释放速率、燃烧热值和耐火极限的相关知识,通过量纲分析法确定固体单体的火灾事故损失特性函数。在此基础上,对于区域内有m个固体单体的情况,以传热学中热辐射理论为基础,运用随机理论的科尔莫弋罗夫-查普曼方程确定单体间的相互影响,最终确定了区域火灾损失特性函数。     

抗高温环保钻井液体系研究

文章选择清洁环保的钻井液处理剂进行抗高温钻井液体系实验研究与评价,对包被增粘剂、降失水剂等进行优选,对抗高温环保钻井液配方进行评价,研究出无毒、无害,抗温能力强、流变性好,失水较低的钻井液体系,现场应用满足高温深井的钻井生产要求。     

南四湖流域水污染防治存在的问题及对策

南四湖通过采用"治、用、保"并举的流域污染综合治理措施,把污染治理与水资源循环利用相结合,取得了明显的成效,但仍面临工业结构性污染严重、城市基础设施建设滞后、面源污染突出等问题。根据南四湖实际情况,可从加大资金筹措力度、继续实施流域综合治理、整合现有港口资源、开展生态养殖、加强执法等方面入手,解决流域水污染防治存在的问题。     

环境法学专业模式建构与发展展望

以中国环境管理干部学院环境法学专业模式构建为研究对象,从专业设置的理论与现实依据、模式建构、专业建设的系列措施、努力方向等方面对环境法学专业建设问题进行了层层剖析,旨在高职高专院校层面、社会层面、教师层面以及学生层面释明设立法学专业的必要性。     

陕西省精细化地质灾害气象预报预警研究

在黄土高原和秦巴山区地质灾害与降水相关特征分析基础上,介绍了陕西省气象台精细化地质灾害气象预报预警模型与业务系统.利用新一代多普勒天气雷达和自动气象站加密资料实现了综合雨量的精细估计,结合GIS地形地貌信息和历史灾害风险分析确定出降水影响系数后,通过计算指标量与灾害临界阈值判断实现了陕西省l 915个乡镇地质灾害的逐日...     

应对重大灾害的轴辐式应急物资储备网络体系

分析了应对重大灾害的应急物资需求的特点和我国现有应急物资储备体系的现状和不足,基于轴辐网络优势,构建了轴辐式应急物资储备网络体系,分析了应急轴辐网络储备体系运行的四个阶段,同时提出了建立轴辐式应急物资储备网络相关具体措施建议,实现中央和地方应急储备库物资、各职能部门储备物资、军队物资、各社会团体储备物资、国内外捐助物资以及企业物资生产能力储备等专业应急物资储备和社会应急物资储备的有效整合,以有助于在较短时间内积聚大量应急物资,扩大应急物资的服务辐射范围,提高应急物资调度效率,以有效应对各类重大灾害。