中国气候变化的科学新认知

了解和认识百年来中国气候发生的变化、引起其变化的驱动因素以及未来的可能变化,可以更好地适应和减缓气候变化。本文综合评估了观测到的中国气候变化事实、中国气候变化的驱动力、中国未来气候变化预估三大方面,分析了气候变暖的趋势、水循环以及降水和冰川变化、极端天气气候事件变化、生物化学循环、海洋和土地覆盖变化及其气候效应以及未来气候变化的特点和趋势等最新科学进展。在中国百年温度趋势、气候系统多气候指标变化特征、极端天气气候事件中的人类活动作用以及气候系统模拟能力等方面的研究有了新的进展。可以看到中国气候变暖趋势持续、大气二氧化碳等长寿命温室气体浓度继续增长、人为强迫影响了多种气候要素在强度和频率的变化,中国陆地生态系统的固碳量增加。本文最后提出未来中国气候变化研究需要进一步加强的问题,包括:中国气候变化中的城市化效应、气候系统内部变率在年代际变化中的作用、气溶胶-云-降雨相互作用的机理、大范围土地利用变化(如大规模生态恢复工程)的气候效应,以及云辐射反馈、海洋环流对气候变化的响应与反馈、气候-碳循环反馈等过程对气候模拟不确定的影响等。     

On the selection of stimulus for the auditory variant of the detection response task method for driving experiments

Objectives: The detection response task (DRT) is a method for measuring attentional effects of secondary tasks on a driver's cognitive load by measuring response times and hit rates to different types of stimuli as indirect indicators of increased cognitive load. ISO 17488 (International Organization for Standardization 2016) only provides guidelines for the technical implementation and measurement methods for the visual and tactile versions (use of visual and tactile stimuli) of the DRT method. This article presents a study with the goal of finding the most appropriate auditory stimulus for the implementation of an auditory version of the DRT method.

Methods: This article presents the results of an experiment in which responses to 7 different auditory DRT stimuli—varying in frequency—were compared while inducing users' cognitive load with a modified n-back task. The experiment was conducted in a surrogate driving environment and in a within-subject design. Response times, hit rates, and secondary task performances were observed as indicators of increased cognitive load.

Results: Significantly shorter response times were found for the white noise signal compared to single-frequency signals. However, the largest differences in response times, for trials without and with a cognitive task, were found for 4- and 8-kHz single-frequency signals. No significant differences were found for hit rates and secondary task performances between the different stimuli.

Conclusions: Consistent significant differences in response times for all tested stimuli prove that the auditory DRT variant is also sensitive to changes in cognitive load. The mean increase in response times of more than 25% for 4- and 8-kHz signals for trials with a cognitive task compared to trials without one indicates that one of these signals could be used as a potential auditory stimulus for the auditory DRT variant.     

基于二氧化钛纳米管有序阵列的氢气探测

基于气体传感器对H_2的泄漏进行探测监控,可以有效预防和控制H_2火灾爆炸事故的发生。通过阳极氧化法制备了高度有序的二氧化钛(TiO_2)纳米管阵列并制成气体传感器元器件,研究其在空气气氛中对H_2的气敏特性。通过粉末X射线衍射(XRD)、扫描电子显微镜(SEM),透射电子显微镜(TEM)表征手段研究了TiO_2纳米管的相组成和微观结构。TiO_2纳米管具有优异的气敏性能,可在200℃以上对H_2进行有效探测,检测极限达到20ppm。325℃对1 000ppm H_2灵敏度为446,响应时间为2s,对H_2选择性好。     

基于Delaunay三角网和地理加权回归的降水空间异常探测方法研究

针对目前已有的降水资料质量控制方法适应性差,降水数据难以模拟局地降水规律的问题。以湖南省为实验区域,利用1985~2014年夏季降水观测数据,定义局部地理空间内降水量发生显著偏离的气象站点为异常,发展了一种结合Delaunay三角网和地理加权回归的降水空间异常探测方法。该方法通过构建不规则三角网来获取各个区域之间稳定合理的地理邻近关系,根据空间邻近关系获取自适应回归带宽,并纳入地理加权回归模型进行计算,最后根据回归残差项的统计分布性质开展空间异常度量与分析。实验表明该方法能有效检测出降水空间异常,可应用于降水数据二次处理时的质量控制阶段,有助于进一步探索局部地理空间内的降水规律。     

Colorado River Floods, Droughts, and Shrimp Fishing in the Upper Gulf of California, Mexico

Accurate procedures that measure hydrologic variability would have great value for evaluating ecosystem impacts of upstream water use in the Colorado River Basin. Many local extractive income-based stakeholders rely directly or indirectly on ecosystem health and are adversely affected when the river does not flow. This study focuses on the impact of little or no Colorado River flow on the Mexican shrimp industry. Although there have been complaints that U.S. diversions of Colorado River flow have greatly impaired the shrimp fishery, this research demonstrates that freshwater rarely reaches the Gulf even during times of flooding, and that other factors such as overfishing may influence the instability of shrimp populations. Advanced very-high-resolution radiometer (AVHRR) satellite imagery was used to assess water volumes diverted away from the channel of the Colorado River and ultimately the Gulf of California during flooding periods. Analysis of data demonstrated that little freshwater actually reaches the Gulf even during floods because of its diversion into a large dry lake bed basin known as Laguna Salada. Fuller use of the Colorado River throughout its entire course to the sea is possible and could benefit a large cohort of users without catastrophic habitat destruction in delta ecosystems. Reconstruction of a natural earthen berm, as proposed by Ducks Unlimited, would maximize the use of floodwaters for ecosystem benefits. These findings have profound implications for local economic activities dependent on hydrologic resources in the Colorado River Delta and Upper Gulf.     

水中六价铬光纤传感检测方法的研究

探讨光纤传感检测探头的原理,建立适应现场检测水中六价铬的方法。水中Cr6+与二苯基碳酰二肼反应生成紫红色产物,光纤探头插入水样中进行测定。其检测浓度范围为0.04～1.0mg/L,最低检出限为0.04mg/L。采用光纤传感测定水中六价铬,为野外和在线检测提供一种新方法。     

新形势下地市级环境监测站转型发展初探

以南京市环境监测中心站的实践为例,初步探讨了地市级环境监测站转型发展的优势和困难、总体思路和分步措施。针对转型中存在的人力不足、人才培养滞后、制度和机制与发展需求不匹配等问题,引入社会检测力量,释放人力,促进人员初步转型,并建立组织管理体系、资金管理体系和质控管理体系,试行人员持证上岗制,为顺利转型提供保障。提出强化人才转型、对外的质控与监管、对内的精细化管理、监测成果的挖掘分析,以及对区县站的扶持,进一步深化转型发展。     

低浓度SO2和NOx 自动监测系统性能评价方法

通过对7种废气自动监测系统的比较研究和现场测试,提出了非分散红外法、紫外差分法、紫外荧光法、化学发光法等多种 SO2和 NO x 自动监测技术在低浓度范围实现准确定量监测的性能评价方法,定义了 CEMS 的系统检出限及其主要影响因素。建议采用系统检出限、线性误差等关键参数作为低浓度 CEMS 的性能评价方法,提出将全系统多点标准气体校准或加标回收率作为验收和质控监督的基本方法。     

Invasive species change detection using artificial neural networks and CASI hyperspectral imagery

For monitoring and controlling the extent and intensity of an invasive species, a direct multi-date image classification method was applied in invasive species (salt cedar) change detection in the study area of Lovelock, Nevada. With multidate Compact Airborne Spectrographic Imager (CASI) hyperspectral data sets, two types of hyperspectral CASI input data and two classifiers have been examined and compared for mapping and monitoring the salt cedar change. The two types of input data are all two-date original CASI bands and 12 principal component images (PCs) derived from the two-date CASI images. The two classifiers are an artificial neural network (ANN) and linear discriminant analysis (LDA). The experimental results indicate that (1) the direct multitemporal image classification method applied in land cover change detection is feasible either with original CASI bands or PCs, but a better accuracy was obtained from the CASI PCA transformed data; (2) with the same inputs of 12 PCs, the ANN outperforms the LDA due to the ANN’s non-linear property and ability of handling data without a prerequisite of a certain distribution of the analysis data.     

Temporal and spatial change detecting (1998–2003) and predicting of land use and land cover in Core corridor of Pearl River Delta (China) by using TM and ETM+ images

Land use/land cover (LULC) has a profound impact on economy, society and environment, especially in rapid developing areas. Rapid and prompt monitoring and predicting of LULC’s change are crucial and significant. Currently, integration of Geographical Information System (GIS) and Remote Sensing (RS) methods is one of the most important methods for detecting LULC’s change, which includes image processing (such as geometrical-rectifying, supervised-classification, etc.), change detection (post-classification), GIS-based spatial analysis, Markov chain and a Cellular Automata (CA) models, etc. The core corridor of Pearl River Delta was selected for studying LULC’s change in this paper by using the above methods for the reason that the area contributed 78.31% (1998)–81.4% (2003) of Gross Domestic Product (GDP) to the whole Pearl River Delta (PRD). The temporal and spatial LULC’s changes from 1998 to 2003 were detected by RS data. At the same time, urban expansion levels in the next 5 and 10 years were predicted temporally and spatially by using Markov chain and a simple Cellular Automata model respectively. Finally, urban expansion and farmland loss were discussed against the background of China’s urban expansion and cropland loss during 1990–2000. The result showed: (1) the rate of urban expansion was up to 8.91% during 1998–2003 from 169,078.32 to 184,146.48 ha; (2) the rate of farmland loss was 5.94% from 312,069.06 to 293,539.95 ha; (3) a lot of farmland converted to urban or development area, and more forest and grass field converted to farmland accordingly; (4) the spatial predicting result of urban expansion showed that urban area was enlarged ulteriorly compared with the previous results, and the directions of expansion is along the existing urban area and transportation lines.