Assessment of the benefits of climate model weights for ensemble analysis in three urban precipitation frequency studies

In hydrology, projected climate change impact assessment studies typically rely on ensembles of downscaled climate model outputs. Due to large modeling uncertainties, the ensembles are often averaged to provide a basis for studying the effects of climate change. A key issue when analyzing averages of a climate model ensemble is whether to weight all models in the ensemble equally, often referred to as the equal-weights or unweighted approach, or to use a weighted approach, where, in general, each model would have a different weight. Many studies have advocated for the latter, based on the assumption that models that are better at simulating the past, that is, the models with higher hindcast accuracy, will give more accurate forecasts for the future and thus should receive higher weights. To examine this issue, observed and modeled daily precipitation frequency (PF) estimates for three urban areas in the United States, namely Boston, Massachusetts; Houston, Texas; and Chicago, Illinois, were analyzed. The comparison used the raw output of 24 Coupled Model Intercomparison Project Phase 5 (CMIP5) models. The PFs from these models were compared with the observed PFs for a specific historical training period to determine model weights for each area. The unweighted and weighted averaged model PFs from a more recent testing period were then compared with their corresponding observed PFs to determine if weights improved the estimates. These comparisons indeed showed that the weighted averages were closer to the observed values than the unweighted averages in nearly all cases. The study also demonstrated how weights can help reduce model spread in future climate projections by comparing the unweighted and weighted ensemble standard deviations in these projections. In all studied scenarios, the weights actually reduced the standard deviations compared to the equal-weights approach. Finally, an analysis of the results' sensitivity to the areal reduction factor used to allow comparisons between point station measurements and grid-box averages is provided.     

海南近海点带石斑鱼野生和养殖群体微卫星多态分析

采用微卫星分子标记技术对海南近海点带石斑鱼野生和养殖群体的遗传变异进行了研究.实验所用点带石斑鱼分别于2005年6月和9月取自海南万宁石斑鱼养殖基地和三亚近海,均为20尾,取全血以酚-氯仿抽提方法提取基因组DNA,利用微卫星引物进行PCR扩增,反应产物经8%非变性聚丙烯酰胺凝胶电泳分离、银染显色,并计算了相应的遗传学参数.结果表明,在野生和养殖群体中, 7个基因座位的等位基因平均数(A)分别为3.29和3.29,每个基因座位有效等位基因数(ae)分别为1.90～3.68和1.83～4.06,野生和养殖群体平均杂合度(Ho)分别为0.790 4和0.833 7;两个群体间的遗传相似性系数为0.832 5,遗传距离为0.183 4.由此可知,点带石斑鱼野生群体的等位基因数、平均有效等位基因数等于养殖群体,而杂合度两群体相当(P=0.637>0.05),说明海南近海点带石斑鱼野生和养殖群体的种质资源较好.     

酚类化合物的生物吸附特征与其结构关系

选用经处理过的盐泽螺旋藻为吸附剂,研究其对10种酚类化合物的吸附行为。结果表明：盐泽螺旋藻对苯酚、邻苯二酚、对苯二酚、邻氨基酚、对氯酚和2,4-二氯酚6种酚均有不同程度的吸附,用Freundlich和Langmuir吸附等温方程描述时,均呈现良好的线性关系;该6种酚的吸附常数k的对数值与其分子连接性指数（²X^v）呈良好的线性关系;盐泽螺旋藻对其余4种酚（邻甲酚、间羟基酚、间氨基酚、间乙酰氨基酚）均不产生吸附。     

地理信息系统在环境模型研究中的应用

结合国内外环境信息系统的研究现状和研究实例,首先分析了ＧＩＳ与环境模型研究结合的必要性和ＧＩＳ在环境模型研究中潜在的应用范围,然后剖析了ＧＩＳ与环境模型研究结合的三阶水平并介绍了ＧＩＳ在环境模型研究中的应用现状,最后分析了ＧＩＳ和环境模型研究结合的发展趋势并给出了ＧＩＳ、ＲＳ、ＥＳ与环境模型理想的结合框架。     

阳-非离子混合表面活性剂对沉积物吸附硝基苯的影响

研究了非离子表面活性剂Triton X-100、阳离子表面活性剂氯化十六烷基吡啶(CPC)及其混合物在沉积物上的吸附行为,探讨了它们对沉积物吸附硝基苯的影响.结果表明,CPC和Triton X-100在沉积物上的吸附等温线均为非线性,吸附量随着平衡浓度的增加急剧增加,并迅速达到最大吸附量.低浓度CPC能明显增加Triton X-100在沉积物上的吸附,而高浓度的CPC则显著降低Triton X-100在沉积物上的吸附.Triton X-100略微降低CPC在沉积物上的吸附.在表面活性剂浓度较低的实际环境中,无论是阳离子或非离子表面活性剂,将主要被土壤或沉积物吸附并固定.硝基苯在沉积物上的吸附等温线为线性.CPC和Triton X-100促进沉积物对硝基苯的吸附,CPC-Triton X-100混合表面活性剂溶液能进一步增强沉积物对硝基苯的吸附.因此,阳离子和非离子混合表面活性剂可增强土壤或沉积物对有机污染物的吸附固定能力,也可以用来制备有机膨润土以提高其吸附处理废水的性能.     

天津地区土壤多环芳烃在剖面中的纵向分布特征

在天津市北部山区、中部农田和东南部油田采油作业区分别采集了土壤样品 ,研究了土壤中多环芳烃 (PAHs)的纵向分布特征 ,并对土壤中多环芳烃的来源进行了分析 .结果表明 ,PAHs含量峰值一般位于土壤表层或次表层 ,并随着土壤剖面的加深而减少 .农田菜地土壤PAHs在 4 0cm深处含量仍然较高 ,而油田仅表层 3cm富集PAHs ,这与耕作土壤表层常受到人为扰动有关 .与高环物质相比 ,低环物质更容易向下迁移 .土壤中有机碳的含量、土壤的性质以及土壤的粒度均是影响PAHs迁移的重要因素 .山区和菜地土壤中PAHs主要来自燃烧源 ,而油田则显示为石油源和燃烧源的混合源 .     

有机垃圾处理机发酵工艺研究

叙述了新型有机垃圾处理机的结构特点,分析了有机垃圾处理的生物发酵过程,通过不同温度、搅拌频率和通风时间的发酵实验,根据发酵效果的不同确定最佳关键工艺参数,为有机垃圾处理机的进一步发展提供依据。     

Characterizing Interpersonal Influence for Grassland Conservation Behaviours in a Unique Population

Interpersonal communication can influence the decisions people make about engaging in conservation behaviours. In-depth interviews with Tibetan pastoralists serve as the basis for examining interpersonal communication patterns and sources of interpersonal influence about grassland conservation behaviours. Herding and family groups are key collectives; salient sources of information vary across types of information. Salient individuals are those with credibility and means control: community leaders, elders, veterinarians, and government officials. Explicit information about conservation comes from religious leaders. The findings have significant implications for understanding the function and nature of interpersonal influence in unique population groups regarding conservation actions.     

固相萃取-气相色谱-FPD法检测生活饮用水中的氧乐果、甲拌磷和二嗪磷残留量

研究建立固相萃取-气相色谱-FPD法检测生活饮用水中的氧乐果、甲拌磷和二嗪磷残留量的分析方法。将采集的生活饮用水过滤后上自动固相萃取仪,选择HLB固相萃取柱净化、富集,丙酮洗脱,洗脱液氮吹至近干,丙酮定容至1.0 mL,上气相色谱-FPD仪检测,外标法定量。实验结果表明,本方法具有快速、准确、高效等特点,可以用于生活饮用水中的氧乐果、甲拌磷和二嗪磷等有机磷类杀虫剂残留量的检测。     

秦岭南北地区农业气候资源时空变化特征

利用秦岭南北地区1960~2016年47个气象站点的观测资料,运用气候倾向率、Mann-Kendall趋势检验、相关分析与反距离加权插值等方法分析了秦岭南北地区光、热、水等农业气候资源的时空变化特征。结果表明：1960年以来,秦岭南北地区气温、≥10℃活动积温呈显著增加趋势,1995年后气温快速上升,并在2002年增温达到显著水平。春、冬、秋季增温明显,空间上秦岭以北增温倾向率大于秦岭以南。 1960~2016年,秦岭南北地区降水量总体呈微弱下降趋势,从时间上看,1995年前降水量以下降为主,1995年后降水量转为上升趋势;从空间上看,1960~2016年,下降较明显地区为秦岭以北、嘉陵江沿线,其次为汉水流域丹江口水库区域;部分地区呈现微弱上升趋势,主要分布在巴巫谷地、汉水流域大巴山等山地段和秦岭南坡东部。相对湿度呈微弱下降趋势;日照时数呈显著下降趋势,四季下降程度为夏>冬>秋>春,下降显著地区为研究区东部平原、汉中盆地、关中盆地及巴巫谷地。 关键词： 农业气候资源,时空变化,秦岭南北地区