Spatio‐temporal variability of the isotopic input signal in a partly forested catchment: Implications for hydrograph separation     

Carles Cayuela  Jrme Latron  Josie Geris  Pilar Llorens 《水文研究》2019,33(1):36-46

The isotopic composition of precipitation (D and ¹⁸O) has been widely used as an input signal in water tracer studies. Whereas much recent effort has been put into developing methodologies to improve our understanding and modelling of hydrological processes (e.g., transit‐time distributions or young water fractions), less attention has been paid to the spatio‐temporal variability of the isotopic composition of precipitation, used as input signal in these studies. Here, we investigated the uncertainty in isotope‐based hydrograph separation due to the spatio‐temporal variability of the isotopic composition of precipitation. The study was carried out in a Mediterranean headwater catchment (0.56 km²). Rainfall and throughfall samples were collected at three locations across this relatively small catchment, and stream water samples were collected at the outlet. Results showed that throughout an event, the spatial variability of the input signal had a higher impact on hydrograph separation results than its temporal variability. However, differences in isotope‐based hydrograph separation determined preevent water due to the spatio‐temporal variability were different between events and ranged between 1 and 14%. Based on catchment‐scale isoscapes, the most representative sampling location could also be identified. This study confirms that even in small headwater catchments, spatio‐temporal variability can be significant. Therefore, it is important to characterize this variability and identify the best sampling strategy to reduce the uncertainty in our understanding of catchment hydrological processes.  相似文献   

厚碳酸盐岩覆盖区RVSP三维地震勘探应用效果分析     

胡小鹏 《山东国土资源》2020,36(5):38-43

该文以中国南方一厚碳酸盐岩覆盖区的RVSP三维地震勘探实例,对RVSP三维地震勘探观测系统和数据采集参数的确定、地面等效处理和波场分离等关键处理技术及地质效果进行了阐述和分析,说明了RVSP在克服表浅层复杂地质条件及环境条件对资料的影响及提高地震资料的分辨率有其特定的优势,同时也提出了RVSP三维地震在采集和处理过程中的难点。  相似文献   

Assessing the ‘two water worlds’ hypothesis and water sources for native and exotic evergreen species in south‐central Chile          下载免费PDF全文

P. Hervé‐Fernández  C. Oyarzún  C. Brumbt  D. Huygens  S. Bodé  N. E. C. Verhoest  P. Boeckx 《水文研究》2016,30(23):4227-4241

Recent studies using water‐stable isotopes (δ¹⁸O and δ²H) have suggested an ecohydrological separation of water flowing to streams or recharging groundwater and water used by trees, known as the ‘two water worlds’ (TWW) hypothesis. In this study, we measured water isotopic composition in precipitation [open field and throughfall, i.e. local meteoric water line (LMWL)] and the mobile water compartment (i.e. stream and soil solution), bulk soil water and xylem water over a period of 1.5 years in two headwater catchments: NF, covered with old growth native evergreen forest (Aetoxicon punctatum, Laureliopsis philippiana and Eucriphya cordifolia), and EP, covered with 4 and 16‐year‐old Eucalyptus nitens stands. Our results show that precipitation, stream and soil solution plot approximately along the LMWL, while xylem waters from all studied tree species plot below the LMWL, supporting the TWW hypothesis. However, we also found evidence of ecohydrological connectivity during the wet season, likely controlled by the amount of antecedent precipitation. These observations hold for all investigated tree species. On both sites, a different precipitation source for stream and xylem water was observed. However, in EP, bulk soil showed a similar precipitation source as xylem water from both E. nitens stands. This suggests that E. nitens may use water that is recharging the bulk soil compartment. We conclude that under a rainy temperate climate, the TWW hypothesis is temporal and does not apply during wet seasons. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

基于UF、GFC及RP-HPLC的长牡蛎(Crassostrea gigas)蛋白抗衰老小分子活性肽(Zel'ner)的纯化及结构解析     

何定芬  谢超  梁佳  梁瑞萍  李海波 《海洋与湖沼》2020,51(1):141-147

牡蛎肉质鲜美,营养丰富,具有很高的食用价值。本研究以舟山长牡蛎(Crassostreagigas)为研究对象,以DPPH自由基清除率为测试指标,通过UF、GFC及RP-HPLC等技术,对牡蛎蛋白酶解液进行分离纯化,获得牡蛎蛋白小分子肽样品,并对其氨基酸组成进行营养性评价。研究结果表明:浓度为30%—100%的硫酸铵处理酶解液的分离效果明显优于低于浓度为30%硫酸铵的分离效果,其DPPH自由基清除率达到52.43%;纯化后得到两种牡蛎蛋白小分子肽分别标记为组分a(Mw1kDa)和组分b(1kDaMw3kDa);组分a中牡蛎蛋白小分子肽分子量分布主要为1995.2Da、1258.9Da、1023.3Da、398.1Da;对牡蛎蛋白小分子肽组分a进行检测,发现其中氨基酸种类及含量丰富,其中必需氨基酸(EAA)含量为18.863%,总氨基酸含量(TAA)为43.3748%,必需氨基酸占总氨基酸43.49%,必需氨基酸与非必需氨基酸(NEAA)的比例为76.95%,风味氨基酸(FAA)含量为18.9147%,占总氨基酸含量的43.61%。综上可见,牡蛎蛋白小分子肽具有极高的营养价值和市场经济效益,此研究为牡蛎蛋白抗衰老小分子活性肽(Zel'ner)的开发提供了新的思路和方向。  相似文献   

基于纵横波保幅分离的粘弹介质弹性波正演模拟     

侯志强  尹文笋  李键  孙永壮  刘云 《中国海洋大学学报(自然科学版)》2020,(1):82-92

地下介质往往表现为粘弹特性,研究基于粘弹假设的数值模拟方法对于正确认识地震波的传播规律和提高地震勘探精度具有重要意义。波动方程正演过程中纵横波的保幅解耦是研究准确的粘弹介质中地震波传播机理的前提,基于散度和旋度算子的纵横波解耦方法会使波场的相位和振幅产生畸变,且解耦后的波场在极性反转位置上无法与分离前混合波场各分量对应。在散度和旋度算子上再做一次梯度和旋度运算的波场分离方法虽然能够克服上述缺陷,但存在保幅性差等问题。本文从粘弹介质中的一阶速度-应力方程出发,推导了矢量纵横波分离的波数域表达式,结合有限差分思路给出了其在空间域的求解方法。本文方法利用纵横波的传播速度对现有的矢量波场分离方法进行振幅校正,并将校正结果分别作为纵波与横波对时间的二阶偏导,实现了粘弹介质中的纵横波分离。模型试算结果表明,本文方法能够克服现有方法的缺陷,获得更具保幅性的波场分离结果。  相似文献   

泡沫塑料吸附分离富集-电感耦合等离子体质谱法测定稀土矿石中的镓   总被引：1，自引：1，他引：0  

董学林  何海洋 《岩矿测试》2016,35(1):42-47

采用电感耦合等离子体质谱法(ICP-MS)测定稀土矿石中的镓,高含量的稀土元素会造成严重的质谱干扰。本文采用聚氨酯泡沫塑料在6 mol/L盐酸介质中吸附样品溶液中的镓后,以0.5 mol/L氯化铵水浴加热解脱30 min,镓的吸附-解脱效率超过99%,稀土元素等干扰物质基本不进入解脱液中,即在富集镓的同时实现了镓与基体元素的高效分离,降低了质谱干扰。本方法检出限低(0.022μg/g),经土壤及水系沉积物标准物质验证,镓的测定值与标准值吻合(绝对偏差为0.38%~4.70%),实际稀土矿石样品的加标回收率为94.1%~100.6%,精密度(RSD)低于4%(n=12),可应用于分析一般地质样品以及稀土矿石中的镓。  相似文献   

A Loop Current experiment: Field and remote measurements     

《Dynamics of Atmospheres and Oceans》2016

An overview of a new comprehensive observational study of the Loop Current (LC) in the eastern Gulf of Mexico that encompassed full-depth and near-bottom moorings, pressure-equipped inverted echo sounders (PIES) and remote sensing is presented. The study array was designed to encompass the LC from the Campeche Bank to the west Florida escarpment. This overview centers about principal findings as they pertain to mesoscale dynamics. Two companion papers provide in-depth analyses. Three LC anticyclonic eddy separation events were observed with good 3D spatial coverage over the 2½ year extent of the field study; the three separations exhibited similar processes after the LC had extended into the eastern Gulf. Large scale (∼300 km wavelength, 40–60 day periods) southward propagating meanders developed on the eastern side of the LC over deep (∼3000 m) water that were the result of baroclinic instability between the upper layer meandering jet and lower layer cyclones and anticyclones. The lower layer was only highly energetic during relatively short (∼2–3 months) intervals just prior to or during eddy detachments because of baroclinic instability. The steepening of the meanders lead to a pinch-off of LC eddies. The deep lower-layer eddies, constrained by the closed topography of the southeastern Gulf, propagated westward across the detachment zone and appear to assist in achieving separation. Small scale (∼50–100 km, periods ∼10 days) frontal eddies, observed on the western side of the LC along the Campeche Bank slope, decay over the deep water of the northern part of an extended LC, and have little influence on lower layer eddies, the east side meanders and the eddy detachment processes.  相似文献   

利用GNSS干涉信号振荡幅度反演土壤湿度   总被引：2，自引：1，他引：1  

汉牟田  张波  杨东凯  洪学宝  杨磊  宋曙辉 《测绘学报》2016,45(11):1293-1300

根据干涉效应和GNSS接收机信噪比估计方法,推导了利用GNSS干涉信号幅度进行土壤湿度反演的模型,建模过程考虑了天线增益、土壤介电常数和噪声的影响。提出了使用AMPD算法从含有噪声的归一化干涉功率曲线中提取干涉峰值与谷值,进而反演了土壤介电常数与土壤湿度的方法,并对其进行了仿真。结果表明,利用提取出来的干涉谷值进行反演性能比峰值好,相对稳定准确的卫星仰角范围为5°~25°,湿度大于0.06cm~3/cm~3时反演结果更为准确,标准差在0.01cm~3/cm~3左右波动。  相似文献   

冰盖下矩形河道的综合糙率          下载免费PDF全文

陈刚  张玉蓉  周密  顾世祥 《水科学进展》2016,27(2):290-298

综合糙率是采用曼宁公式确定河道水位和流量关系的关键参数。在河道冰封期,冰盖的出现增加了流动的阻力,明流条件下确定的综合糙率不再适用,需要重新估算。基于Einstein阻力划分过流断面的原理,冰盖下矩形河道的过水断面可划分为冰盖区、河床区和边壁区。根据总流的连续性方程,在确定各分区糙率系数、水力半径和断面面积的基础上,提出了冰盖下矩形河道综合糙率的计算公式。采用已有的试验水槽测量数据和天然河道实测资料对公式进行了验证,结果表明:公式计算的综合糙率与实测值吻合较好,与Einstein公式和Sabaneev公式相比,计算精度更高;对于冰封水流,宽浅河道采用分区水深代替水力半径进行简化计算的条件有别于明渠水流,在宽深比大于20时,计算结果才满足精度要求。  相似文献   

南极低温降解菌Shewanella sp. NJ49羟化酶分离纯化及最适产酶条件研究     

刘芳明  王以斌  曲长凤  梁强  郑洲  缪锦来  肖天 《海洋科学》2016,40(5):1-8

羟化酶是细菌降解烷烃的关键酶,本文以南极低温降解菌Shewanella sp.NJ49为研究对象,通过硫酸铵沉淀、超滤浓缩及葡聚糖凝胶Sephadex G-75柱层析方法,分离纯化NJ49的羟化酶,获得了单一羟化酶组分,研究了温度、p H、表面活性剂和盐度等环境因素对NJ49羟化酶酶活活性影响。结果表明,羟化酶组分由α、β、γ三个亚基组成,分子质量分别为56,45和36 k D。NJ49最适产酶条件为:温度15℃、p H7.2、盐度55;不同类型表面活性剂对酶的活性影响效应不一,两性离子表面活性剂、阳离子表面活性剂、非离子表面活性剂对酶活没有作用,阴离子表面活性剂+非离子表面活性剂混和剂和阳离子表面活性剂+非离子表面活性剂混和剂能提高羟化酶的活性。  相似文献