Fluctuations of electrical conductivity as a natural tracer for bank filtration in a losing stream     

Tobias Vogt  Eduard Hoehn  Philipp Schneider  Anja Freund  Mario Schirmer  Olaf A. Cirpka 《Advances in water resources》2010

A key parameter used in the assessment of bank filtration is the travel time of the infiltrated river water during the passage through groundwater. We analyze time series of electrical conductivity (EC) in the river and adjacent groundwater observation wells to investigate travel times of young hyporheic groundwater in adjoining channelized and restored sections of River Thur in North-East Switzerland. To quantify mixing ratios and mean residence times we perform cross-correlation analysis and non-parametric deconvolution of the EC time series. Measurements of radon-222 in the groundwater samples validate the calculated residence times. A simple relationship between travel time and distance to the river has not been observed. Therefore, we speculate that the lateral position and depth of the thalweg as well as the type of bank stabilization might control the infiltration processes in losing rivers. Diurnal oscillations of EC observed in the river and in nearby observation wells facilitate analyzing the temporal variation of infiltration. The diurnal oscillations are particularly pronounced in low flow situations, while the overall EC signal is dominated by individual high-flow events. Differences in travel times derived from diurnal and overall EC signals thus reflect different infiltration regimes.  相似文献   

抗高温盐水泥浆的实验研究   总被引：3，自引：0，他引：3  

张琰 《地质与勘探》1999,35(2):61-64,F003

介绍了一种室内优选出的抗高温,抗电解质,性能良好的盐水泥浆体系。  相似文献   

Techniques for determination of trace metals in small samples of size-fractionated particulate matter: phytoplankton metals off central California     

Jay T. Cullen  Robert M. Sherrell 《Marine Chemistry》1999,67(3-4)

The oceanic biogeochemical cycles of many trace elements are dominated by their association with the growth, death, consumption and sinking of phytoplankton. The trace element content of marine phytoplankton reflects nutritional status, species composition, surface area to volume ratios, and interactions with bioactive and toxic elements in the ambient seawater. Despite the ecological and environmental importance of trace element assimilation by autotrophs, there are few modern measurements of trace elements in phytoplankton assemblages from the natural environment. Here we introduce a new method for collection and analysis of size-fractionated particulate samples from practical seawater volumes. We pay particular attention to accurate determination of trace element filter blanks which are typically the limiting factor for analysis of such samples. Metals were determined at very low detection limits by high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) for 11 elements (Ag, Al, Cd, Co, Cr, Cu, Fe, Mn, U, Zn and P, which is used as a biomass normalizer) in three types of polymer filters (0.45, 5.0, and 53 μm pore size) and a quartz fiber filter (0.8 μm pore size). To place these new determinations in a practical context, results are presented for a vertical profile of samples filtered from 1–4 l of coastal seawater (0.3–1.0 mg total solid dry weight) at a station off central California. The results demonstrate that the blanks of the evaluated filter types, precleaned appropriately, are sufficiently low to allow accurate determination of the trace metal content of three size-classes of phytoplankton. At the Pacific station, measured phytoplankton Zn content (as Zn/P) agrees with values predicted from single-species culture studies growing at seawater Zn concentrations expected for coastal waters. The new method has utility as a generally applicable and simple size fractionation technique, and allows determination of natural and pollutant elements in small samples of phytoplankton and particles in coastal, estuarine and offshore marine regimes.  相似文献   

几种主要养殖贝类滤水率的研究   总被引：24，自引：0，他引：24       下载免费PDF全文

林元烧  曹文清  罗文新  郭东晖  郑爱榕  黄长江 《海洋学报》2003,25(1):86-92

在实验室条件下对厦门海域4种主要养殖贝类,僧帽牡蛎、菲律宾蛤仔、缢蛏和翡翠贻贝的滤水率进行研究.结果表明:(1)这4种贝类的滤水率范围为54～74.8cm3/(g·min),滤水率大小顺序依次为僧帽牡蛎、缢蛏、翡翠贻贝、菲律宾蛤仔;(2)单位体重滤水率与个体大小之间呈负幂函数关系(FR=aWb,FR'=aWb-1),b-1值范围在-0.435 6～-0.392之间;(3)僧帽牡蛎和菲律宾蛤仔对中肋骨条藻的滤水率高于对塔马亚历山大藻和锥状施克里普藻的滤水率;(4)僧帽牡蛎和菲律宾蛤仔滤水率与藻类密度之间呈现负幂函数关系(FR'=aDb-1),其b-1值分别为-0.143和-0.215 2.  相似文献   

Chemical Composition and Geologic History of Saline Waters in Aux Vases and Cypress Formations, Illinois Basin     

Ilham Demir  Beverly Seyler 《Aquatic Geochemistry》1999,5(3):281-311

Seventy-six samples of formation waters were collected from oil wells producing from the Aux Vases or Cypress Formations in the Illinois Basin. Forty core samples of the reservoir rocks were also collected from the two formations. Analyses of the samples indicated that the total dissolved solids content (TDS) of the waters ranged from 43,300 to 151,400 mg/L, far exceeding the 35,400 mg/L of TDS found in typical seawater. Cl-Br relations suggested that high salinities in the Aux Vases and Cypress formation waters resulted from the evaporation of original seawater and subsequent mixing of the evaporated seawater with concentrated halite solutions. Mixing with the halite solutions increased Na and Cl concentrations and diluted the concentration of other ions in the formation waters. The elemental concentrations were influenced further by diagenetic reactions with silicate and carbonate minerals. Diagenetic signatures revealed by fluid chemistry and rock mineralogy delineated the water-rock interactions that took place in the Aux Vases and Cypress sandstones. Dissolution of K-feldspar released K into the solution, leading to the formation of authigenic illite and mixed-layered illite/smectite. Some Mg was removed from the solution by the formation of authigenic chlorite and dolomite. Dolomitization, calcite recrystallization, and contribution from clay minerals raised Sr levels significantly in the formation waters. The trend of increasing TDS of the saline formation waters with depth can be explained with density stratification. But, it is difficult to explain the combination of the increasing TDS and increasing Ca/Na ratio with depth without invoking the controversial 'ion filtration' mechanism.  相似文献   

流滑型窝崩水流结构特征及其变化规律          下载免费PDF全文

张幸农  牛晨曦  假冬冬  应强 《水科学进展》2020,31(1):112-119

针对长江中下游河段流滑型窝崩,进行水槽概化模拟试验,依据精细的流场观测数据,分析窝塘附近水流结构特征及变化规律,为探索此类崩岸力学机制奠定基础。结果表明,窝塘附近水流结构可分为口外主流区、口门涡流区和窝塘回流区三大区域。随着窝崩发展,三大区域内水流结构也随之产生变化。口外主流区基本为明渠弯道水流,有明显环流特征;口门涡流区呈现长条形态,其内存在多个大小、形态、位置和强度变化的涡旋,总体规律随主流快速下移不断破碎或分解,口门上、下两端水流呈明显三维特征且脉动性很强,水面波动剧烈;窝塘回流区内为典型空腔回流,随窝崩发展,其范围扩大,中心下移,形态由椭圆形趋向圆形,强度呈现增强-减弱-稳定的趋势。  相似文献   

温度对大珠母贝滤水率的影响   总被引：1，自引：0，他引：1  

刘永  焦宗垚  张春芳 《广东海洋大学学报》2010,30(1):23-26

在实验室条件下,测定不同温度下大珠母贝[Pinctada maxima(Jameson)]的滤水率。结果表明:在15℃、20℃、25℃、30℃4个温度梯度下,大珠母贝的滤水率呈逐渐上升趋势,15℃时滤水率最小,30℃时最大;大、小规格大珠母贝个体滤水率最大值分别为1.045L/h和0.838L/h,最小值分别为0.126L/h和0.102L/h;相同水温条件下,大规格组的个体滤水率大于小规格组,大规格组的单位软体部干重滤水率小于小规格组。温度和个体大小对大珠母贝的滤水率有极显著影响(P<0.01)。  相似文献   

沟纹巴非蛤滤水率的研究   总被引：2，自引：0，他引：2  

王冬梅  李春强  周键  胡朝松  黄姿  刘志昕  彭明 《海洋科学》2008,32(9):42-45

在实验室条件下,用流水装置测定了体质量、昼夜节律、藻密度和流速对沟纹巴非蛤(Paphia exarataPhilippi)滤水率的影响。结果表明:(1)单位体质量滤水率随个体体质量的增加而减小,二者之间呈负幂函数关系:R_f'=0.657w~(-0.6501)。(2)在1个昼夜里,测定了00:00、04:00、08:00、12:00、16:00、20:00共6个时间点的滤水率,滤水率在00:00时最小、08:00时最大,二者差异显著(P<0.05),与其它时刻的滤水率无显著差异。(3)在一定藻密度范围内,滤水率随着藻密度的增加而增大,当藻密度超过(4.5±0.11)×10~4个/mL 之后,滤水率反而降低。(4)在3.6～9.0 L/h 的流速范围内,滤水率随流速的增大而增大,当流速达到7.2 L/h 后滤水率增加不显著(P>0.05)。  相似文献   

反硝化条件下河岸渗滤过程中苯胺的降解   总被引：2，自引：0，他引：2  

吴耀国  曾睿  惠林  尹德忠 《地球科学》2006,31(2):273-278

通过河岸渗滤作用(riverbankfiltration, RBF) 诱发河水的补给, 增大地下水的允许开采量可以满足更多居民生活饮用水需求.受人类活动的影响, 河流等地表水体遭受苯胺污染, 可能通过RBF进入地下水, 以致饮用该地下水存在健康风险.为研究反硝化条件下, 苯胺在RBF中的转化, 采集渭河河床沉积物及沿岸地下水含水层的含水介质, 装置土柱, 进行土柱动态模拟实验.经过153 d的实验研究发现, 利用苯胺对RBF中土著反硝化微生物进行驯化, 大约经过37d菌种完全适应.具有该菌种的RBF系统, 对苯胺具有巨大降解能力, 在NO3——N约为23.0 mg/L的条件下, RBF系统可使40、80甚至400 mg/L浓度的苯胺100%降解, 矿化率分别达97.99%、91.39%与75.30%.反硝化条件下, 苯胺在RBF中的降解仅有少部分经过脱氨作用, 绝大部分与腐殖质以共价键形式形成耦合物, 该耦合物更易为微生物降解, 且降解过程中不产生对研究环境微生物有毒的中间产物, 可实现反硝化条件下RBF中苯胺的连续降解.   相似文献   

富营养化初期湖泊放养鲢(Hypophthalmichthys molitrix)、鳙(Aristichthys nobilis)控藻生态效果的初步评估     

杨姣姣  过龙根  尹成杰  陈晓希  倪乐意 《湖泊科学》2019,31(2):386-396

放养鲢（Hypophthalmichthys molitrix）、鳙（Aristichthys mobilis）控制富营养化湖泊蓝藻水华暴发是当前最有效的手段之一.为评估富营养化初期湖泊鲢、鳙控藻的生态效果,2016年在洱海红山湾开展原位围栏鲢、鳙控藻实验,对围栏内外的浮游生物群落结构及水环境因子的变化进行对比分析,同时测定了围栏内鲢、鳙的生长及摄食节律.结果表明：围栏内鲢、鳙呈现匀速生长,围栏生存环境适宜.根据Egger''s模型估算鲢、鳙的日摄食量分别为24.96%和18.18%,鲢的日粮高于鳙;滤食率结果表明,鲢对浮游植物的摄食率高于鳙（分别为3.01和2.19 L/（g·h）,而鳙对浮游动物的滤食率高于鲢（分别为18.61和13.54 L/（g·h））.研究期间,围栏内外水体理化因子无显著差异;但围栏内外微囊藻生物量差异明显,并且在7月达到生物量峰值（围栏内为1.7 mg/L,围栏外为2.4 mg/L）.鲢、鳙对浮游植物的优势种类——微囊藻和隐藻有明显的削减效果,6-8月逐渐上升并在8月达到最高（64%）;当浮游植物优势种由微囊藻替换为硅藻门和绿藻门的种类时,鲢、鳙的削减效率不明显（10-11月为负值）.此外,鲢、鳙放养显著降低了浮游甲壳动物的总生物量和枝角类生物量.因此,结合实验结果得出,鲢具有更高的控藻能力,尤其对微囊藻水华,但同时具备了较高对浮游甲壳动物的削减能力,需要进一步分析富营养化初期湖泊——洱海中实施非经典生物操纵的适宜性.  相似文献