Topographic,pedologic and climatic interactions influencing streamflow generation at multiple catchment scales   总被引：1，自引：0，他引：1  

Geneviève Ali  Doerthe Tetzlaff  Chris Soulsby  Jeffrey J. McDonnell 《水文研究》2012,26(25):3858-3874

Dominant flow pathways (DFPs) in mesoscale watersheds are poorly characterized and understood. Here, we make use of a conservative tracer (Gran alkalinity) and detailed information about climatic conditions and physical properties to examine how temporally and spatially variable factors interact to determine DFPs in 12 catchments draining areas from 3.4 to 1829.5 km² (Cairngorms, Scotland). After end‐member mixing was applied to discriminate between near surface and deep groundwater flow pathways, variation partitioning, canonical redundancy analyses and regression models were used to resolve: (i) What is the temporal variability of DFPs in each catchment?; (ii) How do DFPs change across spatial scales and what factors control the differences in hydrological responses?; and (iii) Can a conceptual model be developed to explain the spatiotemporal variability of DFPs as a function of climatic, topographic and soil characteristics? Overall, catchment characteristics were only useful to explain the temporal variability of DFPs but not their spatial variation across scale. The temporal variability of DFPs was influenced most by prevailing hydroclimatic conditions and secondarily soil drainability. The predictability of active DFPs was better in catchments with soils supporting fast runoff generation on the basis of factors such as the cumulative precipitation from the seven previous days, mean daily air temperature and the fractional area covered by Rankers. The best regression model R² was 0.54, thus suggesting that the catchments’ internal complexity was not fully captured by the factors included in the analysis. Nevertheless, this study highlights the utility of combining tracer studies with digital landscape analysis and multivariate statistical techniques to gain insights into the temporal (climatic) and spatial (topographic and pedologic) controls on DFPs. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

夏季西北冰洋表层淡水分布的总碱度示踪研究   总被引：1，自引：0，他引：1       下载免费PDF全文

高众勇  孙恒  陈立奇  张凡 《极地研究》2012,24(2):120-128

利用中国第三次北极科学考察在西北冰洋所进行的海水总碱度的测量,通过海水、海冰融化水以及河源淡水三个端元总碱度特征的显著差异计算西北冰洋夏季表层海水中淡水所占的比例。研究表明,西北冰洋海冰融化水所占比例最大区域在加拿大海盆区75°N附近,这是冰缘带位置,往北向高纬度的冰密集中逐渐增加。而河源淡水的组份则与北冰洋的环流密切相关,并且在西北冰洋水体中逐渐累积。  相似文献   

西北冰洋总碱度与溶解无机碳的分布          下载免费PDF全文

孙恒  高众勇  陈立奇  张凡 《极地研究》2012,24(1):1-7

2008年7～9月,中国进行了第三次北极科学考察。本研究即利用此次宝贵的科学考察机会,在西北冰洋现场采集大量的海水样品,进行二氧化碳体系（主要包括总碱度(TA),和溶解无机碳(DIC)等）研究。得到了西北冰洋二氧化碳体系参数的分布,并对其控制因素进行了讨论。夏季西北冰洋表层海水总碱度（TA）、盐度归一化总碱度（nTA,nTA =TA*35/S）、溶解无机碳（DIC）和盐度标准化溶解无机碳（nDIC,nDIC=DIC*35/S）的范围分别为1757～2229μmol kg-1,2383～2722μmol kg-1,1681～2034μmol kg-1,2119～2600μmol kg-1。由于受到河水和海冰融化水的稀释,表层DIC和TA的浓度都比较低。78°N以南西北冰洋上层水柱中TA与盐度有良好的正相关关系,比较保守,在盐度大于30时,主要是海水端元与河水端元混合,在盐度小于30时主要是海水端元与海冰融化水端元的混合。在楚科奇海,DIC分布主要受到有机质生产或降解的主控,而加拿大海盆无冰区混合层DIC分布的主控因素是海水与海冰融化水的保守混合。  相似文献   

滴定水样总碱度中终点的确定和指示剂的选择     

刘汉初  倪桃英 《岩矿测试》1991,10(1):60-62

本文讨论了水样中总碱度含量与滴定等当点的变化关系和甲基橙在不同pH值下颜色的变化情况。试验了可用于滴定水样总碱度的常见的10种酸碱指示剂。结果表明,用溴甲酚绿指示终点优越,颜色突跃清楚。  相似文献   

High-resolution varve studies in Baldeggersee (Switzerland): Project overview and limnological background data     

B. Wehrli  A. F. Lotter  T. Schaller  M. Sturm 《Aquatic Sciences - Research Across Boundaries》1997,59(4):285-294

This introduction to a series of high-resolution varve studies in Baldeggersee provides both an overview of the different subprojects as well as background information on relevant limnological trends. The project was based on a new method of in-situ freezing of unconsolidated surficial sediments in deep lakes. With this freeze-core technique a detailed, high-resolution stratigraphy of the varved sediments at the deepest point of Baldeggersee has been established for the period of 1885–1993. Annual and seasonal sediment samples were analyzed. Concentrations of redox active metals in sediments were calibrated as proxy indicators for the reconstruction of hypolimnetic oxygen conditions. Particle size analysis and varve measurements were used to discriminate between the influence of nutrients and climate on sediment formation and accumulation. Baldeggersee is an ideal system for calibrating indicators of deep-water oxygen concentrations because it underwent dramatic changes in nutrient loading and redox conditions during this century. The hypolimnion has been seasonally anoxic for the last 100 years and phosphorus content decreased by a factor of five in the last 20 years. Meromixis was observed between 1960 and 1980. Since 1983 the deep water has been artificially oxygenated. This well documented change in deep-water oxygen concentration represents a unique whole-lake experiment that can be used to analyze the geochemical response of the sediments.  相似文献   

Impact of regional geology, land use and flow path on stream water chemistry in a small watershed     

Jae Gon Kim Jin-Soo Lee Kyung Seok Ko Tack Hyun Kim Chul-Min Chon Gyoo Ho Lee Tong Kwon Kim Yongje Kim Sung Won Park 《中国地球化学学报》2006,25(B08):140-140

Stream water chemistry is dependent on the physical, chemical and biological processes occurring in the watershed. Understanding the governing mechanism of the stream water chemistry in a watershed is the first step for the water quality management. The study area drains a total catchment area of 1.46 km^2 and consists of forest （80%）, upland （15%） and rice paddy field （5%）. The studied area has two distinctive bedrocks, quartzite and schist. We periodically collected the stream water samples at mainstream and tributaries and the pH, electrical conductivity （EC）, alkalinity and the concentrations of cations and anions of the collected stream water samples were determined in the field and laboratory. The all collected water samples were nearly neutral and the EC and concentrations of Na, K, Ca, Sr, Si and HCO3 of the stream water samples collected from the schist terrain had greater values than those from the quartzite terrain. The mainstream running along the boundary of schist and quartzite terrains had the intermediate values of the tributaries. The stream water samples collected in and near the upland showed a high concentration of NO3^- than those of forest regardless the lithology. The stream pathway was also directly reflected on the chemistry of stream water. The stream water drained in the forest of quartzite terrain had the lowest values of alkalinity, EC and concentrations of cations and anions but the stream water drain in the upland of schist terrain had the highest values of EC and concentrations of cations and anions, especially NO3^-.  相似文献   

Chemical oxygen demand of seawater determined with a microwave heating method     

LIULi JIHongwei LIUYing XINHuizhen 《中国海洋大学学报(英文版)》2005,4(2):152-156

This paper investigates a microwave heating method for the determination of chemical oxygen demand (COD) in seawater. The influences of microwave-power, heating time and standard substances on the results are studied. Using the proposed method, we analyzed the glucose standard solution, the coefficient of variation being less than 2%. Compared with the traditional electric stove heating method, the results of F-test and T-test showed that there was no significant difference between the two methods, but the microwave method had slightly higher precision and reproducibility than the electric stove method. With the microwave heating method, several seawater samples from Jiaozhou Bay and the South Yellow Sea were also analyzed. The recovery was between 97.5% and 104.3%. This new method has the advantages of shortening the heating time, improving the working efficiency and having simple operation and therefore can be used to analyze the COD in seawater.  相似文献   

Tidal variations of some physico-chemical parameters in Blanca Bay,Argentina     

Marta Susana Orozco Storni  Rubén José Lara  Adán Edgardo Pucci 《Estuarine, Coastal and Shelf Science》1984,19(4):485-491

Oxygen, alkalinity, nutrients, pH, temperature and salinity were measured through tidal cycles in two points of Blanca Bay. A clear dependence of nutrients, oxygen and alkalinity with salinity and tide conditions was observed in the inner point, being attenuated in the outer one.  相似文献   

南海东北部之海水碳酸盐现况     

黄明祥  陈镇东 《台湾海峡》1995,14(2):124-134

为探讨南海的海水碳酸盐现况，本文利用“海研一号”三个航次（第266、287及316航次）的机会，搜集南海东北角的碳酸盐因子，如温度盐度、pH值、总碱度及总二氧化碳等。南海深层水具有西菲律宾海水深约2200m的水团特性，实测结果显示此两水团的碳酸盐因子并没有明显的差异。由滞留时间、无机碳及有机碳分解速率计算结果显示，南海深层水的滞留时间以40a较为合理。  相似文献   

Manganese cycling in a eutrophic lake — Rates and pathways     

John Sternbeck 《Aquatic Geochemistry》1995,1(4):399-426

The redox processes regulating transport of Mn in the water column of a eutrophic, dimictic lake (Lake Norrviken, Sweden) are interpreted based on a one-dimensional diffusion-reaction model for Mn(II). It is found that rates and rate constants for oxidation and reduction vary greatly with depth and also with time during the season of stratification. Calculated rates show that Mn(II) oxidation and reduction generally occur in narrow depth intervals (25–50 cm). This is in good agreement with measured profiles of particulate Mn (MnO _x ). Maximum oxidation rate constants (assuming first order kinetics) at each date are in the first half of the season <1 d^–1, but then increases to a rather constant value of about 25 d^–1. These high rate constants are indicative of microbiological involvement in the Mn(II) oxidation. This is further evidenced by SEM-EDS analysis showing Mn enriched particles morphologically similar toMetallogenium. Reductive dissolution of Mn oxides occurs mainly in the zone just below the zone of maximum oxidation rate. The release of Mn(II) is accompanied by production of alkalinity and CO₂. The relation between production rates of Mn(II) and alkalinity indicates that Mn oxides act as terminal electron acceptors in the bacterially mediated oxidation of organic matter. However, the Mn²⁺/CO₂ ratio is significantly lower than what is expected from this process. It is suggested that the Mn reduction is coupled to fermentation. Close coexistence of Mn reduction and oxidation at high rates, such as found in the water column of this lake, facilitates rapid and continuous regeneration of reducible Mn oxides. This gives rise to a quantitatively important mechanism of organic matter oxidation in the water column.  相似文献