Integrating intraseasonal grassland dynamics in cross-scale distribution modeling to support waterbird recovery plans

Despite much discussion about the utility of remote sensing for effective conservation, the inclusion of these technologies in species recovery plans remains largely anecdotal. We developed a modeling approach for the integration of local, spatially measured ecosystem functional dynamics into a species distribution modeling (SDM) framework in which other ecologically relevant factors are modeled separately at broad scales. To illustrate the approach, we incorporated intraseasonal water-vegetation dynamics into a cross-scale SDM for the Common Snipe (Gallinago gallinago), which is highly dependent on water and vegetation dynamics. The Common Snipe is an Iberian grassland waterbird characteristic of European agricultural meadows and a member of one of the most threatened bird guilds. The intraseasonal dynamics of water content of vegetation were measured using the standard deviation of the normalized difference water index time series computed from bimonthly images of the Sentinel-2 satellite. The recovery plan for the Common Snipe in Galicia (northwestern Iberian Peninsula) provided an opportunity to apply our modeling framework. Model accuracy in predicting the species’ distribution at a regional scale (resulting from integration of downscaled climate projections with regional habitat–topographic suitability models) was very high (area under the curve [AUC] of 0.981 and Boyce's index of 0.971). Local water-vegetation dynamic models, based exclusively on Sentinel-2 imagery, were good predictors (AUC of 0.849 and Boyce's index of 0.976). The predictive power improved (AUC of 0.92 and Boyce's index of 0.98) when local model predictions were restricted to areas identified by the continental and regional models as priorities for conservation. Our models also performed well (AUC of 0.90 and Boyce's index of 0.93) when projected to updated water-vegetation conditions. Our modeling framework enabled incorporation of key ecosystem processes closely related to water and carbon cycles while accounting for other factors ecologically relevant to endangered grassland waterbirds across different scales, allowed identification of priority areas for conservation, and provided an opportunity for cost-effective recovery planning by monitoring management effectiveness from space.     

多因素影响下巷道变形特性数值模拟研究

基于FLAC3D有限差分软件对开挖深度、侧压力系数、断面形状等多因素影响下的巷道变形参数进行正交试验，根据正交试验分析结果，分别选取同一深度条件下的圆形、马蹄形、直墙拱形、矩形巷道进行模拟试验并以圆形巷道作为典型断面，对不同深度下的巷道变形特征进行模拟试验。研究结果表明:开挖深度对巷道开挖后的应力差变化影响明显，断面形状对巷道围岩内的塑性区深度和具有显著影响；巷道开挖后的塑性区深度和随形状指数增加而呈线性增长趋势，圆形巷道的塑性区深度和最小，矩形最大；应力差随着巷道开挖深度的增加呈线性增加，深部开采应重视巷道内的应力分布情况。     

梯度模式原理及其应用

本文推导梯度模式，引用大气边界层湍流系数进行实际运算，与现场大气环境监测结果对照；同时与高斯模式计算结果比较，得出该模式在城市复杂流场的实用性．     

Improving the extraction of tetrachloroethylene from soil columns using surfactant gradient systems

In this work, we extend the recently developed gradient approach for surfactant-enhanced remediation of dense non-aqueous phase liquid (DNAPL)-impacted sites. The goal of the gradient approach is to maximize the DNAPL solubilization capacity in swollen micelles (Type I aqueous microemulsions) while at the same time minimizing the potential for DNAPL mobilization. In this work, we introduce a modified version of the capillary/trapping curve that we refer to as the gradient curve to help interpret and/or design the gradient approach. The gradient curve presents the residual DNAPL saturation as a function of interfacial tension and microemulsion viscosity. This approach demonstrates that keeping a low viscosity of the microemulsion phase is not only important for keeping a low head loss during surfactant flooding but also to prevent oil mobilization. Eight microemulsion systems were evaluated in this research; these systems were evaluated based on their tetrachloroethylene (PCE) solubilization capacity, interfacial tension (IFT), viscosity, density, and coalescence kinetics. Two of these systems were chosen for evaluation in site-specific column tests using an increasing electrolyte gradient to produce a decreasing IFT/increasing solubilization gradient system. The column studies were conducted with media from Dover Air Force Base in Dover, DE. Both solubilized and mobilized DNAPL were quantified. During the column studies, we observed that substantial PCE was mobilized when the residual level of PCE in the column was significantly higher than the steady-state residual saturation level being approach (as predicted from the gradient curve). Four column studies were performed, three of which were used to asses the validity of the gradient curve in predicting the residual saturation after each gradient step. From these tests we observed that starting IFTs of less than 1 mN/m all produced the same mobilization potential. In the last column, we used an additional gradient step with an initial IFT above 1 mN/m to dramatically reduce the amount of PCE mobilize. Based on the good agreement between column results and projections based on the gradient curve, we propose this as a preferred method for designing gradient surfactant flushing systems.     

中国高等植物干质量热值特点

植物干质量热值是植物干物质完全燃烧所释放的能量值,反映了植物光合作用中固定太阳辐射能的能力。文章收集国内已有的129科、460属、1110种维管植物的干质量热值数据,并加上作者自测的8种苔藓植物干质量热值进行统计分析和差异性检验,分析国内高等植物干质量热值特点。结果显示,植物不同器官的平均GCV为繁殖体(19677.23J·g-1)>叶(19518.22J·g-1)>枝(19455.91J·g-1)>皮(19183.12J·g-1)>干(19122.49J·g-1)>根(18701.44J·g-1);群落中不同组分平均GCV的排序是乔木层(19672.48J·g-1)>灌木层(19218.62J·g-1)>凋落物层(18689.86J·g-1)>草本层(17682.47J·g-1)>苔藓层(15645.44J·g-1);在不同生活型的植物中,挺水植物(18492.67J·g-1)>浮水植物(16381.25J·g-1)>沉水植物(14589.09J·g-1);平均GCV多年生草本GCV(17903.28J·g-1)>一年生草本(17652.74J·g-1);常绿型木本植物各器官均大于落叶型木本植物,针叶树种各器官均大于阔叶树种;从不同气候型来看,高纬度地区的温带大陆性季风气候以及高寒大陆性气候的植物平均GCV较高,低纬度的热带季风气候区的植物比亚热带季风气候区的高,温带大陆性半干旱气候区内最低。     

我国农田土壤碳氮耦合特征的区域差异

利用中国第2次土壤普查数据,分析了稻作和旱作方式下农田耕层土壤有机碳和全氮特征及其区域差异。结果表明,水田土壤有机碳和全氮含量分别为旱地的147.8%和145.5%,但水田碳氮含量的区域变异低于旱地。全国水田和旱地土壤有机碳氮比值分别为10.8和9.9,各区域水田土壤碳氮比值普遍高于旱地,其中东北水田最高,而华东旱地和西北旱地最低。旱地碳氮比值的区域变异显著,水田则不显著。农田耕层土壤有机碳和全氮含量呈显著正相关,除华北地区外,各区域无论水田还是旱地其碳氮含量之间相关系数都超过0.8,达极显著水平。由此可见,我国农田耕层土壤有机碳和全氮含量之间存在显著耦合关系,而且不同利用方式和区域之间差异显著;相同氮水平下,水田土壤可能储存更多的有机碳。     

普兰店湾潮流场数值模拟

针对近年来我国近海海洋环境影响评价的需要，运用具有移动边界的潮波动力学有限 差分模型，模拟了普兰店湾 潮 流场，复演了该湾的潮流结构和时空变化过程。验证结果表明，模拟计算的流速平均差为－1.52cm/s，流向平无差为-2.5 度，完全符合潮流预报的精度要求。     

浦东开发区河网水动力学模型研究

文章应用的 Preismann 隐式差分格式,具有计算精度高,稳定性条件限制少,可为后续的河网水质模型提供完整的水力参数等特点。用这一隐式差分格式对圣维南方程组进行数值离散,采用双扫除法(追赶法)可推导出不同边界条件下的各种追赶方程。模型的计算结果与实测值的拟合程度较高。最后,通过计算结果分析了浦东开发区河网流场的基本特点,指出了该地区水环境容量较小的水动力学方面的原因,提出了改善水环境容量的方法。     

基于DMSP/OLS数据的中国碳排放时空模拟与分异格局

精准模拟和精细尺度获取碳排放的时空动态信息，对于合理制定差别化的区域碳减排政策具有重要意义.利用DMSP/OLS夜间灯光数据在完成年内和跨年数据的校正、像元去饱和、异常值剔除的基础上，提取了城市建成区范围，并以中国大陆为研究对象，根据夜间灯光数据和碳排放统计数据之间的定量关联，构建面板数据模型模拟了2000~2013年中国的碳排放量；采用Theil-Sen Median趋势分析方法与Mann-Kendall检验，探讨了14年间中国碳排放量的时空变化趋势及空间分布特征.结果表明：系统校正后的DMSP/OLS夜间灯光影像构建面板模型模拟的碳排放量拟合精度较高，2002，2007和2012年多尺度回归检验的决定系数R²值分别为0.893，0.955和0.951.2000~2013年中国碳排放时空演化差异显著，稳慢增长型和迅猛增长型分别占碳排放区域总面积的77.6%和19.4%，稳慢增长型面域宽广，迅猛增长型主要位于都市区及都市连绵区.受城市规模及城市化发育程度的影响，迅猛增长型空间结构呈"空心型"与"中心型"空间指向性分异.研究提出，促进经济增长方式和发展模式的实质性转变、因地制宜差别化的减排措施与省区联动策略的实施是"精准减排"目标实现的重要途径.     

基于级别差法的地下水水质评价方法筛选技术研究

地下水水质评价是地下水污染防控和水环境管理的基础.不同评价方法会得到不同的评价结果,因此如何选择合适的评价方法至关重要.目前,缺乏科学、客观的地下水水质评价方法筛选技术.基于此,以洛阳市为例,采用内梅罗指数法、模糊综合评价法和基于免疫进化算法优化的普适法（简称"普适法"）3种方法开展地下水水质评价,通过建立级别差方法,定量筛选最适用评价方法.结果表明:①模糊综合评价法-内梅罗指数法、普适法-模糊综合评价法、普适法-内梅罗指数法3种统计方法计算得到的级别差小于0的比例占比分别为34.62%、19.24%和46.16%,大于0的占比分别为19.23%、23.07%和26.92%,因此模糊综合评价法评价得到的地下水水质级别 < 普适法评价得到的地下水水质级别 < 内梅罗指数法评价得到的地下水水质级别.②模糊综合评价法最适用于研究区地下水水质现状评价,采用该方法评价得到研究区地下水水质分为优良（Ⅰ类）、良好（Ⅱ类）、较好（Ⅲ类）、较差（Ⅳ类）和极差（Ⅴ类）5类（参照GB/T 14848-2018《地下水质量标准》）,以良好和较好水质为主,造成地下水水质较差的组分主要为COD_Mn、总硬度、硝酸盐和汞.研究显示,级别差法可作为定量的地下水水质评价方法筛选技术,能够为地下水水质评价研究提供新的思路.