黄土高原半干旱区侧柏林群落土壤呼吸日变化及季节动态变化特征

Desertification is one of the most serious eco-environmental problems around Qinghai Lake. Based on GIS and RS, GIS analysis was used to obtain the information of spatial-temporal change and different pattern of desertification in each county around Qinghai Lake in four phases of 1976, 1987, 1995 and 2006. Using the function of intersect and overlay supported by ARCGIS, with analyzing attributes of vector RS images, we obtained transition data and established transfer matrix of land-use types in recent 30 years, besides, protracted land-use transition maps of all desertification classes. In further, we analyzed transition quantity and direction of desertification in each county, moreover, reconstructed the process of spatial-temporal evolution of desertification. The results are showed below: (1) it′s the transition between desertified land and others but not in the desertified that played the main role in Gangcha and Gonghe County, while the transfer between desertified lands were greater than that with other land-use types in Haiyan County. (2) Extremely severe desertified land mainly distributes in Ketu and Sand Islands that belongs to Haiyan County, and moderate desertified land in riversides of Gangcha County, also, the light desertification expanded too rapidly to become the most desertified land-use type in the surrounding of Qinghai Lake since 1976. (3) By using relative change rate of desertified land, the regional variability rank from top to toe was Gangcha, Haiyan and Gonghe.     

种群水平生态风险评价方法概述及其在环境管理中的应用

生态风险评价的目的是保护生态系统功能的完整性、稳定性和持久性,为环境风险管理提供理论依据。然而,目前常见的用于保护生物的化学污染物浓度阈值大多是以个体水平的毒性试验结果为基础,忽略了物种在时间和空间相互作用等因素,不能够完全保护生态环境安全和生态系统功能的延续性。本文从生态风险评价的概念、目的和意义引出种群水平生态风险评价在环境管理应用的重要性,综述了种群水平生态风险评价的科学问题(如密度依赖、遗传变异和空间结构等),归纳了种群水平风险评价主要模型方法及其应用(如Euler-Lotka方程、预测矩阵、个体模型、空间模型和动态能量预算模型等),列举了各国现有法律法规中关于种群水平生态风险评价的规定,以期为种群水平生态风险评价方法研究及在环境管理中的应用提供有益借鉴。     

城市创新能够驱散雾霾吗?--基于空间溢出视角的检验

中国多城市群大范围持续遭遇雾霾等空气环境问题,不仅严重影响着人民生活健康,同时成为制约中国社会经济发展的主要瓶颈。创新驱动作为引领发展的重要源泉,是治理城市雾霾的重要手段。因此,本文利用2004—2016年中国地级市PM_2.5浓度、创新等数据,基于STIRPAT模型,通过空间计量方法在同时考虑空间横向维度及时间纵向维度下就中国城市创新对雾霾的影响进行了实证分析,并进一步从城市创新对雾霾的动态效应、作用距离阈值等多个角度进行了稳健性检验。实证结果表明:①中国城市雾霾污染呈现明显的空间溢出效应和高排放俱乐部集聚特征。②中国城市创新具有积极的减霾作用。从横向空间维度来看表现为积极的空间溢出效应,但存在一定的有效距离阈值。从纵向时间维度来看,减霾效应整体存在边际递减态势。③交通便利化及能源效率的提高有效抑制了城市雾霾污染的加剧,以煤为主的能源结构仍是城市雾霾污染加剧的一大诱因。基于上述事实,本文提出以下政策建议:中国在城市雾霾治理过程中应实施科学规划,布局联防联控。防止城市"单边"治霾努力成果被周边城市的"泄漏效应"所削减;聚集创新要素,打造创新型城市引擎。在城市群内部形成创新竞争、合作机制,创新重塑城市群发展模式以缓解城市雾霾污染;考虑到城市创新对于雾霾治理红利存在边际递减态势,除上述减霾渠道外,治霾政策仍需坚持从源头着手,优化产业、能源结构,促进能效、路效提高,最终成就美丽城市。     

Microscale Spatial Variation in Forest Litter Phytotoxicity

The spatial variation (within a 100 × 100 m plot) in the pollution of forest litter with heavy metals (Cu, Cd, Pb, and Zn), its acidity, and phytotoxicity (measured by the results of the root test using seedlings from a genetically homogeneous sample of common dandelion (Taraxacum officinale s.l.) have been estimated. Forest litter has been sampled in three zones differing in the toxic impact of long-term polymetal pollution by emissions from a copper-smelting plant emissions in the Middle Urals. The phytotoxicity variation is maximum in a moderately polluted plot, where both very high and very low pollution levels were observed, which determines a substantially nonlinear dose–effect relationship. The litter phytotoxicity is mainly accounted for by exchangeable forms of metals. Biological testing of samples from the most polluted plot has demonstrated marked antagonism between heavy metals and acidity.     

Associations of Decadal to Multidecadal Sea‐Surface Temperature Variability with Upper Colorado River Flow1

Abstract: The relations of decadal to multidecadal (D2M) variability in global sea‐surface temperatures (SSTs) with D2M variability in the flow of the Upper Colorado River Basin (UCRB) are examined for the years 1906‐2003. Results indicate that D2M variability of SSTs in the North Atlantic, North Pacific, tropical Pacific, and Indian Oceans is associated with D2M variability of the UCRB. A principal components analysis (with varimax rotation) of detrended and 11‐year smoothed global SSTs indicates that the two leading rotated principal components (RPCs) explain 56% of the variability in the transformed SST data. The first RPC (RPC1) strongly reflects variability associated with the Atlantic Multidecadal Oscillation and the second RPC (RPC2) represents variability of the Pacific Decadal Oscillation, the tropical Pacific Ocean, and Indian Ocean SSTs. Results indicate that SSTs in the North Atlantic Ocean (RPC1) explain as much of the D2M variability in global SSTs as does the combination of Indian and Pacific Ocean variability (RPC2). These results suggest that SSTs in all of the oceans have some relation with flow of the UCRB, but the North Atlantic may have the strongest and most consistent association on D2M time scales. Hydroclimatic persistence on these time scales introduces significant nonstationarity in mean annual streamflow, with critical implications for UCRB water resource management.     

The Sensitivity of California Water Resources to Climate Change Scenarios1

Abstract: Using the latest available General Circulation Model (GCM) results we present an assessment of climate change impacts on California hydrology and water resources. The approach considers the output of two GCMs, the PCM and the HadCM3, run under two different greenhouse gas (GHG) emission scenarios: the high emission A1fi and the low emission B1. The GCM output was statistically downscaled and used in the Variable Infiltration Capacity (VIC) macroscale distributed hydrologic model to derive inflows to major reservoirs in the California Central Valley. Historical inflows used as inputs to the water resources model CalSim II were modified to represent the climate change perturbed conditions for water supply deliveries, reliability, reservoir storage and changes to variables of environmental concern. Our results show greater negative impacts to California hydrology and water resources than previous assessments of climate change impacts in the region. These impacts, which translate into smaller streamflows, lower reservoir storage and decreased water supply deliveries and reliability, will be especially pronounced later in the 21st Century and south of the San Francisco bay Delta. The importance of considering how climate change impacts vary for different temporal, spatial, and institutional conditions in addition to the average impacts is also demonstrated.     

Effects of Riparian Areas,Stream Order,and Land Use Disturbance on Watershed‐Scale Habitat Potential: An Ecohydrologic Approach to Policy1

Abstract: Spatio‐temporal linkages between hydrologic and ecologic dimensions of watersheds play a critical role in conservation policies. Habitat potential is influenced by variation along longitudinal and lateral gradients and land use disturbance. An assessment of these influences provides critical information for protecting watershed ecosystems and in making spatially explicit, conservation decisions. We use an ecohydrologic approach that focuses on interface between hydrological and ecological processes. This study focuses on changes in watershed habitat potentials along lateral (riparian), and longitudinal (stream order) dimensions and disturbance (land use). The habitat potentials were evaluated for amphibians, reptiles, mammals, and birds in the Westfield River Watershed of Massachusetts using geographic information systems and multivariate analysis. We use a polynomial model to study nonlinear effects using robust regression. Various spatial policies were modeled and evaluated for influence on species diversity. All habitat potentials showed a strong influence along spatial dimensions and disturbance. The habitat potential for all vertebrate groups studied decreased as the distance from the riparian zone increased. Headwaters and lower order subwatersheds had higher levels of species diversity compared to higher order subwatersheds. It was observed that locations with the least disturbance also had higher habitat potential. The study identifies three policy criteria that could be used to identify critical areas within a watershed to conserve habitat suitable for various species through management and restoration activities. A spatially variable policy that is based on stream order, riparian distance, and land use can be used to maximize watershed ecological benefits. Wider riparian zones with variable widths, protection of headwaters and lower order subwatersheds, and minimizing disturbance in riparian and headwater areas can be used in watershed policy. These management objectives could be achieved using targeted economic incentives, best management practices, zoning laws, and educational programs using a watershed perspective.     

Individual changes in human EEG caused by 450 MHz microwave modulated at 40 and 70 Hz

This study was aimed to investigate the changes in the human electroencephalographic (EEG) signal caused by modulated low-level microwaves. The 450 MHz microwave exposure modulated at 40 Hz and 70 Hz frequencies was applied to a group of 15 volunteers. The field power density at the scalp was 0.16 mW/cm². Ten cycles of the exposure (1 min on and 1 min off) at both modulation frequencies were applied. Analysis of the EEG signal was performed using three different methods: nonlinear method of scaling analysis for length distribution of low variability periods (LDLVP), relative changes in EEG energy (S-parameter) and beta ratio (H-parameter). The analysis revealed significant changes caused by microwave for the whole group (H-parameter method). The exposure caused increase of the EEG beta power (S-parameter method). Statistically significant changes in EEG were detected for four subjects (26.7%) at 40 Hz modulation frequency (LDLVP method).     

灾害模拟和后果分析软件架构

本文为基于GIS的公共安全应急体系中各灾害模拟和后果分析模块,研究并建立了一个从概念到实现的统一可扩展的接口,使公共安全灾害模拟和后果分析领域的研究成果能被广泛共享,并且更容易建立一个整合各类已有研究成果的软件体系.并且,本文结合"国家十五重点科技攻关(滚动)项目:合肥市公共安全应急示范试点研究"项目给出了原型实现.     

福建省台风灾害时空变化分析

根据福建省灾害性气象年鉴和福建省气候影响评价资料,建立以县域为单元的福建省台风灾害数据库,运用Excel软件和M ap info技术,重建了1980~2005年福建台风灾害时空动态格局。研究表明:福建台风灾害年际变化总体呈波动上升趋势,年内80%左右集中在7~9月份,群发性强。空间上集中在沿海地区,灾情明显存在3个高值中心,即闽中的莆田、福清、长乐和平潭,闽南的漳浦、云霄和诏安,闽东北的霞浦和福鼎;致灾因子与灾情灾次比空间分布错位,体现承灾体脆弱性对台风灾害的影响。分阶段研究表明:台风灾害致灾因子变化不太明显,但灾情呈明显增强趋势,进一步反映环境不稳定性和承灾体脆弱性对台风灾害的影响机制。