轨道尺度下东亚夏季风降水的北方主导演变模态

众多古气候记录的分析表明：轨道尺度气候变化下我国北方地区的季风降水变化显著,该现象的理解对于深入认识东亚夏季风降水的长期演变模态具有重要意义。本文基于瞬变古气候模拟的分析发现：在轨道尺度气候变化下,东亚夏季风降水的变化中心位于季风区北边界附近的半干旱区,是季风环流整体性演变及季风区北边界摆动的综合作用结果。东亚夏季风降水的轨道尺度演变模态与古气候记录的指示相一致,但与当前观测记录给出的以年际尺度变化为主的模态显著不同,说明东亚夏季风降水对气候变化的响应与气候变化的时间尺度有关。进一步的分析表明：轨道尺度气候变化下东亚夏季风北方降水的响应幅度取决于气候变化的驱动因素,其中轨道辐射的影响最为显著。     

岩溶山地撂荒地演变研究—以郎溪槽谷区为例

中国山区面积广、坡耕地比重大,耕地撂荒不仅关系到山区农地的合理利用和可持续发展政策的制定,还对生态环境问题产生影响.因此,本文以2004年、2010年、2014年、2017年朗溪槽谷遥感影像等为数据源,通过景观格局指数、缓冲区分析及结合槽谷高程分析朗溪槽谷撂荒地分布格局、演变规律、驱动机制和撂荒效应.结果得出:耕地撂荒...     

岷江上游干旱河谷海拔梯度上四川黄栌(Cotinus szechuanensis)叶片的生态解剖

运用生态解剖学的方法对岷江上游干旱河谷海拔梯度上乡土优势灌木——四川黄栌(Cotinus szechuanensis)的叶片解剖特征进行了比较分析.观测的解剖学参数有叶片总厚度、表皮厚度、栅栏组织厚度(P)、海绵组织厚度(S)、P/S的比值、主脉厚度(V)、主脉中直径>50μm导管分子的数目及直径.结果表明:1)四川黄栌叶片具有中生型结构特征,但在不同海拔高度存在差异,这是其适应干旱环境的结构基础.随着海拔的升高,叶总厚度、栅栏组织厚度、P/S值和主脉厚度以及导管分子数目等均呈增大趋势,而导管分子直径减小;表皮厚度、海绵组织厚度等无明显差异.2)多元统计分析显示,叶肉组织厚度和叶片总厚度主要受温和度的影响,并随着温和度的降低而增大;P/S值和导管分子数目主要与年降水量和土壤含水量的变化有关,随着水分增加,P/S值和导管分子数目增大,而导管分子直径减小.因此,岷江上游干旱河谷地区年降雨量、土壤含水量与温和度是影响四川黄栌叶片解剖结构的主要环境因子.图1表3参28     

Assessment of Alternative Methods for Statistically Downscaling Daily GCM Precipitation Outputs to Simulate Regional Streamflow

This study applied three statistical downscaling methods: (1) bias correction and spatial disaggregation at daily time scale (BCSD_daily); (2) a modified version of BCSD which reverses the order of spatial disaggregation and bias correction (SDBC), and (3) the bias correction and stochastic analog method (BCSA) to downscale general circulation model daily precipitation outputs to the subbasin scale for west‐central Florida. Each downscaled climate input dataset was then used in an integrated hydrologic model to examine differences in ability to simulate retrospective streamflow characteristics. Results showed the BCSD_daily method consistently underestimated mean streamflow because the highly spatially correlated small precipitation events produced by this method resulted in overestimation of evapotranspiration. Highly spatially correlated large precipitation events produced by the SDBC method resulted in overestimation of the standard deviation of wet season daily streamflow and the magnitude/frequency of high streamflow events. BCSA showed better performance than the other methods in reproducing spatiotemporal statistics of daily precipitation and streamflow. This study demonstrated differences in statistical downscaling techniques propagate into significant differences in streamflow predictions, and underscores the need to carefully select a downscaling method that reproduces precipitation characteristics important for the hydrologic system under consideration.     

Climate change induced eutrophication of cold-water lake in an ecologically fragile nature reserve

Aquatic ecosystem sustainability around the globe is facing crucial challenges because of increasing anthropogenic and natural disturbances. In this study, the Tianchi Lake, a typical cold-water lake and a UNESCO/MAB(Man and Biosphere) nature reserve located in high latitude and elevation with the relatively low intensity of human activity was chosen as a system to examine the linkages between climate change and eutrophication. As a part of the UNESCO Bogda Man and Biosphere Reserve, Tianchi Lake has been well preserved for prevention from human intervention, but why has it been infected with eutrophication recent years? Our results show that climate change played a significant role in the eutrophication in the Tianchi Lake. Increased temperature, changed precipitation pattern and wind-induced hydrodynamic fluctuations in the summer season were suggested to make a major contribution to the accelerated eutrophication. The results also showed that the local temperature and precipitation changes were closely linked to the large-scale atmospheric circulation, which opens the door for the method to be applied in other regions without local climatic information. This study suggests that there is an urgent need to take into consideration of climate change adaptation into the conservation and management of cold-water lakes globally.     

海陆风对天津市PM2.5和O3质量浓度的影响

静稳天气下局地环流往往会对污染物的传输扩散起重要作用.根据天津市地处渤海西岸,常年受到海陆风影响的特点,综合气象、环境资料及HYSPLIT模型,针对沿海、市区、城郊、山区等代表性站点,研究了海陆风对天津市ρ（PM_2.5）和ρ（O₃）的影响.结果表明:①2015年天津市海陆风天数为78 d,占全年的22%;海陆风多集中于6-9月,其中,7月海陆风日最多、2月最少.②ρ（PM_2.5）和ρ（O₃）季节性变化和空间分布特征不同.春、夏两季ρ（PM_2.5）山区最高、城郊最低;秋、冬两季ρ（PM_2.5）市区最高、山区最低.春、秋两季ρ（O₃）沿海最高、市区最低;夏季ρ（O₃）山区最高、沿海最低.③海陆风对ρ（PM_2.5）有扩散作用,对ρ（O₃）有增加作用.海陆风对沿海ρ（PM_2.5）扩散作用最为明显,致使冬、秋两季ρ（PM_2.5）分别下降20.2%和7.9%;对城郊ρ（O₃）增加作用最为明显,致使秋、夏两季ρ（O₃）分别升高39.8%和16.2%.④个例研究表明,海风向内陆推进过程中垂直方向最高可达1 000 m,受海风影响天津市ρ（PM_2.5）下降,陆风使得ρ（PM_2.5）小幅上升,海陆风总体起扩散作用;海陆风使天津市ρ（O₃）日变化出现3个峰值,日均值明显增大,其中,城郊增幅（68.2%）最大.研究显示,海陆风对天津市ρ（PM_2.5）有扩散的作用,但会增高ρ（O₃）.      

山西省沁河流域农村生活污水入河水质研究

针对农村生活污水管理的需求,在水生态功能区和水环境控制单元的基础上提出了农村生活污水入河水质核算方法.具体步骤包括:①根据地貌类型、降水蒸发量、植被和土壤类型等指标,进行水生态功能区划分;②在水生态功能分区基础上,结合水文单元和行政区边界,划定水环境控制单元;③对控制单元内的水环境容量进行计算,并调查核算各类污染源污染物排放入河量,然后基于水环境容量和污染物入河量确定农村生活污水污染物排放限值.结果表明,沁河流域可划分为2个一级水生态功能区和7个二级水生态功能区,并划分为15个水环境控制单元.以控制单元内沁河上游水质改善区为例,区域内农村生活污水COD排放限值为134.05 mg·L~(-1),且此标准下河流不满足接纳农村污水进行NH_3-N消减的条件.在以上研究成果基础上,提出了农村生活污水分区分级管理措施建议.     

Buoyancy and turbulence-driven atmospheric circulation over urban areas

In the buoyancy and turbulence-driven atmospheric circulations (BTDAC) that occur over urban areas where the approach means wind speeds are very low (less than turbulent fluctuations and typically < 3 m/sec), the surface temperatures are significantly higher than those in the external rural areas, and the atmosphere above the mixing layer is stably stratified. In this paper, the mechanisms of BTDAC formation are studied through laboratory experiments and modelling, with additional low-level inflow from external rural areas and a divergent outflow in the opposite direction in the upper part of the mixed layer. Strong turbulent plumes in the central region mix the flow between lower and higher levels up to the inversion height. There are shear-driven turbulent eddies and weaker buoyant plumes around the periphery of the urban area. As the approach flow is very weak, the recirculating streamlines within the dome restrict the ventilation, and the dispersion of pollution emitted from sources below the inversion height leading to a rise in the mean concentration. Low-level air entrained from rural areas can, however, improve ventilation and lower this concentration. This trend can also be improved if the recirculating structure of the BTDAC flow pattern over urban areas breaks down as a result of the surface temperature distribution not being symmetrical, or as the approach wind speed increases to a level comparable with the mean velocity of circulation, or (except near the equator) the urban area is large enough that the Coriolis acceleration is significant.     

ZL-1与PAM联用治理煤泥水的研究

针对煤泥水难以自然沉降的问题，研究了煤泥水的性质，提出了新的混凝剂ZL—1与PAM联用的治理方法。该方法简单，处理效果好，处理后上清水完全回用于洗煤，实现了洗水闭路循环。     

小龙潭电厂冲渣水系统零排放改造工程

详细介绍了小龙潭电厂冲渣水回收系统改造成闭路循环“零排放”的工艺及设计过程,分析了原系统不合理的原因和改造前后的经济比较,为火电厂废水处理与重复利用提供了设计与运行经验。