Relative abundance,age structure,and body size in mudpuppy populations in southwestern Ontario

Little is known of mudpuppy (Necturus maculosus) population structure and ecology; some populations in the Great Lakes are thought to be in decline. Mudpuppies are the obligate hosts for the mudpuppy mussel (Simpsonaias ambigua), a species that is endangered in Canada and in many Great Lakes states. We surveyed mudpuppies from the Sydenham River, the only known Canadian locality of the mudpuppy mussel, in order to generate information on relative density, deformity rates and population age/size structure and used this information to compare them to known mudpuppy populations from Great Lakes sites in the Detroit River, Lake St. Clair and Long Point in Lake Erie. Deformity rates were elevated at some sites in the Sydenham River. The relative density of mudpuppies in the Sydenham River was lower than that of other Great Lakes sites and their age was skewed towards younger individuals. Although at lower densities than at other Great Lakes sites, the mudpuppy population in the Sydenham River appears stable and is showing signs of recruitment which bodes well for the future of the mudpuppy mussel population of the river.     

黄土高塬沟壑区水土保持对小流域地表径流的影响

水土保持对径流的作用是水土流失治理中一个亟待回答的实际问题．本文用小流域平行对比观测法，分析了黄土高塬沟壑区水土保持对小流域地表径流的数量及其时间分布特征的影响，表明在黄土高塬沟壑区，水土保持能使小流域产洪次数减少、地表径流模数和径流系数减小；使小流域地表径流模数的年际变率增大；在洪水产流过程中，水土保持使流域产流起始时间滞后，径流持续时间缩短，瞬时流量及洪峰流量降低以至消失     

黄土高原小流域雨水资源可持续利用指标体系及评价方法研究

针对黄土高原雨水资源利用现状和小流域雨水资源化特点,以小流域为单元,以雨水资源为研究对象,借鉴可持续发展理论,遵循科学、实用及简明的原则,构建雨水资源可持续利用评价指标体系,并利用均方差权数决策方法,对流域雨水资源可持续利用进行全面分析和定量评价。     

基于分布式水文模拟的流域土壤水分时间稳定性分析

针对大范围地面土壤水监测会耗费大量人力物力等问题,为了获取密度较高同时又准确可靠的流域土壤水数据用于时间稳定性分析,寻找可以反映流域土壤水平均状况的代表性点,利用分布式水文土壤植被模型(DHSVM)模拟淮河黄泥庄水文站以上小流域293个采样网格上、中、下三层土壤含水量数据。结果显示:垂向方向上,黄泥庄流域土壤水分时间稳定性随深度递减;流域上层和中层具备时间稳定性特征的代表性点具有较高的一致性,易发生于流域主要土壤和植被类型覆盖区域,在此区域布设测点观测土壤水,可以更准确快速地捕获代表黄泥庄流域上层和中层平均土壤水分特征;采样点7、17和215可作为上、中层土壤的流域平均土壤水代表性点,利用它们预测流域土壤水平均值,可降低观测成本。研究成果可为流域土壤水监测方案设计提供参考。     

子流域划分对HSPF模型径流模拟效果的影响

在水文水质模拟过程中,子流域划分数量直接影响模拟结果的精确度,确定最佳子流域划分方案对提高模拟精确度至关重要。基于PEST-HSPF模型,以中河流域为例,在相同参数及不同参数条件下,采用PEST自动校准方法,判断子流域划分数量对流量模拟精确度的影响。结果表明,在相同水文参数下,子流域划分数量变化时,模拟流量的纳什系数(NSE)和可决系数(R2)在0.65~0.78之间波动,其中子流域划分数量在10~20之间对模拟结果的精确度影响最大;在不同水文参数下,径流模拟结果的NSE与R2随子流域划分数量的增加先增大后减小,相对误差(RE)在子流域划分数量介于1~10之间时急剧下降后趋于稳定;子流域划分对HSPF水文模拟效果影响显著,表现出阈值效应,当划分数量超出阈值范围时,径流模拟精度均会受到很大影响。     

Vapor specific extents of uptake by nanometer scale charged particles

The uptake of vapor molecules by nanometer scale aerosol particles (clusters) is of fundamental importance in aerosol science; uptake is the first step of condensational growth in both the ambient as well as in condensation based particle detectors. However, uptake is not well understood at the nanometer scale. We examined the uptake of organic vapor molecules by nanometer scale sodium chloride cluster ions ((NaCl)_x(Na⁺)_z and (NaCl)_x(Cl^?)_z) using a differential mobility analyzer coupled with a time-of-flight mass spectrometer. Through monitoring cluster ion inverse mobilities as functions of solvent vapor pressure in the mobility analyzer, the extent of uptake was monitored for 1-butanol, ethanol, methyl ethyl ketone (MEK), and toluene. With butanol vapor pressures in the <300 Pa range, shifts in inverse mobility in excess of a factor of 2 were observed for nearly all examined clusters. Ethanol and MEK uptake led to shifts for positively charged cluster ions upwards of a factor of 1.5. Ethanol exposure led to similar sized shifts for negatively charged clusters ions, while MEK exposure led to negative ion inverse mobility shifts less than a factor of 1.3. Toluene was sorbed much less efficiently than the other solvents; toluene exposure led to shifts in inverse mobility below a factor of 1.2. In total, relative inverse mobility shifts, which are direct functions of the extent of vapor uptake, were found to be only weakly dependent on cluster ion size when compared to the influence of vapor molecular structure and cluster ion charge polarity. Classical (Kelvin-based) models are found inadequate to explain the observed mobility shifts, and we instead used a site-specific, Langmuir type model to describe the vapor uptake behavior by the cluster ions.

© 2017 American Association for Aerosol Research     

坝头单薄分水岭边坡支护方案探讨

大坝两岸单薄分水岭条形山体边坡支护对水库大坝安全运行起到重要意义,对此,阐述惠州抽水蓄能电站上水库单薄分水岭边坡支护采用钢筋砼框架锚杆加干砌石护坡面的处理措施.     

集中入流滞时演进型流域地貌汇流模型

在Ｓｔｒａｈｌｅｒ河流分级法的基础上，提出了单元级别的确定原则，并进一步定义了概念性流域地貌汇流模型．为了将河道洪水演算方法移置到流域汇流模型中，还定义了“滞时演进河段”这一新的概念性元素．推导了三级流域瞬时单位线，选用内罚函数法估计模型参数，实例检验，模型拟合精度较高．     

论邓小平、江泽民法治思想

邓小平、江泽民是我党第二代和第三代领导集体的核心，他们的法治思想各具特色，对中国民主法制建设作出了巨大贡献。邓小平、江泽民法治思想理论具有继承性和与时俱进的创新性，共同构成我国改革开放、全面建设小康社会时期依法治国、建设法治国家的理论来源。     

黄土高原沟壑区小流域人居环境规划的生态学途径--以陕北枣子沟小流域为例

试图将生态规划方法应用于黄土高原沟壑区小流域人居环境的研究中．首先从区域背景和调研资料入手，运用德尔菲法筛选了对人居环境建设影响较大的限制因子，通过层次分析法、地图叠加法对陕北枣子沟流域自然生态系统进行了生态敏感性分析和生态适宜度评价．在量化分析的基础上建立了小流域尺度下“生态优先”的生态安全格局和流域发展用地功能分区．分别从生态化、集约化和专业化的角度就人居环境、土地利用和产业布局提出了规划构想．