Accuracy of Short‐Term Demographic Data in Projecting Long‐Term Fate of Populations

Short‐term surveys are useful in conservation of species if they can be used to reliably predict the long‐term fate of populations. However, statistical evaluations of reliability are rare. We studied how well short‐term demographic data (1999–2002) of tartar catchfly (Silene tatarica), a perennial riparian plant, projected the fate and growth of 23 populations of this species up to the year 2010. Surveyed populations occurred along a river with natural flood dynamics and along a regulated river. Riparian plant populations are affected by flooding, which maintains unvegetated shores, while forest succession proceeds in areas with little flooding. Flooding is less severe along the regulated river, and vegetation overgrowth reduces abundance of tartar catchfly on unvegetated shores. We built matrix models to calculate population growth rates and estimated times to population extinction in natural and in regulated rivers, 13 and 10 populations, respectively. Models predicted population survival well (model predictions matched observed survival in 91% of populations) and accurately predicted abundance increases and decreases in 65% of populations. The observed and projected population growth rates differed significantly in all but 3 populations. In most cases, the model overestimated population growth. Model predictions did not improve when data from more years were used (1999–2006). In the regulated river, the poorest model predictions occurred in areas where cover of other plant species changed the fastest. Although vegetation cover increased in most populations, it decreased in 4 populations along the natural river. Our results highlight the need to combine disturbance and succession dynamics in demographic models and the importance of habitat management for species survival along regulated rivers. Precisión de Datos Demográficos de Corto Plazo en la Proyección del Destino de Poblaciones a Largo Plazo     

基于两种受体模型的太原市大气降尘来源解析及季节变化特征

于2019年11月至2020年12月期间在典型工业城市太原市开展了降尘采样和降尘化学组分分析.采样期间,太原市平均降尘量约为7.9t/(km²·30d),并呈现在4~6月较高.在选取的8个监测区域中,清徐和巨轮的平均降尘量较高,分别为10.7t/(km²·30d)和10.6t/(km²·30d).降尘化学组分质量中地壳元素(Ca、Si、Al)占比较高,巨轮和桃园监测区域的降尘中Fe元素的质量显著高于其他监测区域.将降尘量和化学组分分析结果分别纳入正定矩阵因子分解(PMF)和偏目标转换-正定矩阵分解(PTT-PMF)两种受体模型中对太原市降尘进行了定量来源解析.通过比较两种受体模型的拟合性能和解析的因子谱发现:PTT-PMF受体模型相较于PMF能够更好地区分出降尘中城市扬尘源和建筑尘源这两类相似的尘源.结果表明,太原市降尘主要有六种来源:城市扬尘源(PMF:35%,PTT-PMF:35%)、建筑尘源(PMF:29%,PTT-PMF:28%)、钢铁工业源(PMF:14%,PTT-PMF:14%)、燃煤源(PMF:13%,PTT-PMF:12%)、二次无机盐(PMF:5%,PTT-PMF:6%)、机动车尾气排放源(PMF:4%,PTT-PMF:5%).两种受体模型得到的平均来源贡献结果相似,而建筑尘源和钢铁工业源的季节变化趋势则有一定的差异.粗粒径源类(城市扬尘源和建筑尘源)是太原市降尘的主要来源,两者对降尘的贡献率超过了60%,并在春季贡献率(4~6月)较高.     

大规模空气质量监测数据缺失处理方法实证研究

基于2016年1月至2021年7月的全国1654个国控监测点小时级的6种污染物空气质量监测数据,研究缺失值处理方法、效果及其影响.模拟实验表明交替最小二乘下的低秩矩阵插补算法相比于其他缺失值处理方法拥有更小的均方根误差、平均百分比误差,更高的相关系数和更快的运算速度,在大规模数据集上性能更优.实证分析表明应用文本方法得到的插补值是有效且合理的,缺失值插补前后污染物浓度评估值会有±10%以内的变化,插补后的数据集更加准确和完备.本文建议在基于空气质量监测数据研究时应先采用本文中的缺失数据处理方法,对监测数据中存在的缺失数据进行插补,提高研究所使用监测数据的完整性,保证相关计算结果的准确性和有效性.     

地震灾害损失预测的动态分析模型

本文提出了一个地震灾害预测的动态分析模型。这个模型基于概率理论基础,考虑了一个城市因建设的发展,新房屋日益增多,部分旧房屋被淘汰,对城市抗震能力引起的变化;和由于经济的发展,社会财富的增加,对地震损失的影响。为解决这—问题,文中提出了动态震害矩阵和动态损失矩阵的求解方法。根据这一方法可以预测未来不同年代的地震经济损失。     

正定矩阵因子分解模型在环境中多环芳烃源解析方面的应用

<正>定矩阵因子分解模型(PMF)自1993年开发至今,其在环境中持久性有毒物质(PTS),尤其是多环芳烃(PAHs)源解析中的应用取得了重大研究进展。简要介绍了PMF模型的基本原理,在综述该模型用于土壤/沉积物、大气及水体中PAHs源解析现状的基础上,结合其在实际工作的应用,评述了其在环境中PAHs源解析方面的应用潜力及发展前景。     

高浓度沼气流在矿井风流中的稀释过程的研究

研究了煤矿高浓度沼气排放中沼气与风流的混合、稀释过程；分析了平衡浓度的计算；通过实验室模拟实验，确定了湍流情况下混合长度的经验公式；导出了描述沼气浓度场的对流扩散方程，并应用一维解描述沼气浓度的沿程变化规律。从而达到安全、有效地排放高浓度沼气，防止了瓦斯爆炸事故的发生。     

Quantifying sediment-associated metal dispersal using Pb isotopes: Application of binary and multivariate mixing models at the catchment-scale

In this study Pb isotope signatures were used to identify the provenance of contaminant metals and establish patterns of downstream sediment dispersal within the River Maritsa catchment, which is impacted by the mining of polymetallic ores. A two-fold modelling approach was undertaken to quantify sediment-associated metal delivery to the Maritsa catchment; employing binary mixing models in tributary systems and a composite fingerprinting and mixing model approach in the wider Maritsa catchment. Composite fingerprints were determined using Pb isotopic and multi-element geochemical data to characterize sediments delivered from tributary catchments. Application of a mixing model allowed a quantification of the percentage contribution of tributary catchments to the sediment load of the River Maritsa. Sediment delivery from tributaries directly affected by mining activity contributes 42-63% to the sediment load of the River Maritsa, with best-fit regression relationships indicating that sediments originating from mining-affected tributaries are being dispersed over 200 km downstream.     

Influence of extracellular matrix on the proliferation of human amniotic fluid cells in vitro

Factors which influence the proliferation of human amniotic fluid cells in vitro have potential importance in reducing the time for prenatal diagnosis. Fibroblast growth factor (FGF) has been shown to be mitogenic for human amniotic fluid cells. The observation that cells which respond to FGF in vitro produce their own extracellular matrix (ECM), led to the use of an ECM as a substrate to assess proliferation. Pooled amniotic fluid cells maintained on an ECM prepared from bovine corneal endothelial cells demonstrated a significant increase in proliferation when compared with cells maintained on plastic substrate in the presence or absence of FGF. If FGF was added to cultures of amniotic fluid cells maintained on ECM, further increases in proliferation were noted compared with cells maintained on ECM in the absence of FGF. These results indicate that the substrate upon which amniotic fluid cells are maintained can have a profound influence on their proliferation.     

Destratification and oxygenation efficiency of a water-lifting aerator system in a deep reservoir: Implications for optimal operation

Thermal stratification is a common phenomenon in lakes and reservoirs and has a significant influence on water quality dynamics.Heihe Reservoir is a canyon-shaped reservoir in Shaanxi Province with strong thermal stratification.Therefore,eight water-lifting aerators(WLAs) were installed in this reservoir,which could overcome thermal stratification and increase oxygenation with gas flows between 20 and 50 m3/hr,and oxygenate the hypolimnion with gas flows less than 20 m3/hr.To examine the destratification efficiency of the WLA system,we used a threedimensional hydrodynamic module based on MIKE 3 to simulate the thermal structure of Heihe Reservoir and compared the simulations with measured data.Results showed that operation of the WLA system promoted water mixing and effectively oxygenated the hypolimnion.Through the established energy utilization assessment method,the energy utilization efficiency of the WLA system was between 5.36% and 7.30%,indicating the capability of the technique for destratification in such a large reservoir.When the surface water temperature dropped to the theoretical mixed water temperature calculated by the energy utilization assessment method,reducing gas flow could save energy.This would prevent anaerobic conditions from occurring in the bottom water and maintain good water quality in Heihe Reservoir.     

污泥厌氧过程中磷释放与SMP特性研究

以城市污水处理厂剩余污泥为实验污泥,研究污泥厌氧过程中磷释放和溶解性微生物代谢产物（SMP）的变化特性,检测了不同厌氧时长下总磷（TP）,SMP中蛋白质与多糖含量,利用三维荧光光谱与液相色谱-有机碳测定仪（LC-OCD）进一步探究了SMP的组分分布状况,应用灰色关联度分析了TP与各组分的相关性.结果表明：随着厌氧时间延长,蛋白质,多糖浓度逐渐增加,TP浓度呈现先增大后减小的趋势,TP浓度在厌氧4d最高,达到14.15mg/gVSS,说明污泥厌氧过程中存在最优释磷时间;将三维荧光光谱分为7个荧光区域,平行因子（PARAFAC）分析表明紫外光区类富里酸和类腐殖酸物质荧光强度随着厌氧时间的延长逐渐增大,微生物代谢产物的荧光强度先增大后减小;SMP中生物高聚物和腐殖酸（Humics）等大分子物质浓度逐渐增大,中分子前驱物呈现先增大后减小的趋势,而小分子物质呈现先减小后增大的趋势;蛋白质、多糖和Humics浓度与TP浓度的关联性显著.研究结果可为优化污泥厌氧释磷,提高磷回收效率提供理论支持.