Isotopic and hydrochemistry spatial variation of sulfate for groundwater characterization in karstic aquifers          下载免费PDF全文

Antonio González‐Ramón  Manuel López‐Chicano  Fernando Gázquez  Juan José Durán‐Valsero  Antonio Pedrera  Ana Ruiz‐Constán  Elena González‐Egea 《水文研究》2017,31(18):3242-3254

The Sierra Gorda aquifer is one of the most extensive of southern Spain. The main groundwater discharge is produced at its northern boundary through several high‐flow springs. In this study, stable isotopes of dissolved sulfate (δ³⁴S and δ¹⁸O) and groundwater chemistry were used to determine the origin of the sulfate and to characterize the groundwater flow. We sampled the main springs, as well as other minor outlets related to perched water tables, in order to determine the different sources of SO₄^2? (e.g., dissolution of evaporites and atmospheric deposition). The substantial difference in the amount of dissolved SO₄^2? between the springs located in its northwestern part (≈25 mg/L) and those elsewhere in the northern part (≈60 mg/L) suggests zones with separate groundwater flow systems. A third group of springs, far from the northeastern boundary of the permeable outcrops, shows higher SO₄^2? content than the rest (≈125 mg/L). The isotopic range of sulfate (?0.3‰ to 14.82‰ V‐CTD) points to several sources, including dissolution of Triassic or Miocene evaporites, atmospheric deposition, and decomposition of organic material in the soil. Among these, the dissolution of Triassic gypsum—which overlies the saturated zone as a consequence of the folds and faults that deform the aquifer—is the main source of SO₄^2? (range from 12.79‰ to 14.82‰ V‐CTD). This range is typical for Triassic gypsum. The higher karstification in the western sector, together with important differences in the saturated thickness between the western and eastern sectors, would also be due to the tectonic structure and could explain the difference in SO₄^2? contents in the water. This singular arrangement may cause a higher residence time of groundwater in the eastern sector; thus, a higher contact time with Triassic evaporitic rocks is inferred. Accordingly, the stable isotopes of SO₄^2? are found to be a valuable tool for identifying areas with different flow systems in the saturated zone of karstic aquifers, as well as for evaluating aspects such as the degree of karstification .  相似文献   

Middle to Late Pleistocene lake‐level fluctuations of Lake El'gygytgyn,far‐east Russian Arctic     

Grigory Fedorov  Andrei A. Andreev  Elena Raschke  Volker Wennrich  Georg Schwamborn  Olga Y. Glushkova  Olaf Juschus  Anja Zander  Martin Melles 《Boreas: An International Journal of Quaternary Research》2019,48(2):516-533

Lake El'gygytgyn, located in central Chukotka, Russian Arctic, was the subject of an international drilling project that resulted in the recovery of the longest continuous palaeoclimatic and palaeoenvironmental record for the terrestrial Arctic covering the last 3.6 million years. Here, we present the reconstruction of the lake‐level fluctuations of Lake El'gygytgyn since Marine Isotope Stage (MIS) 7 based on lithological and palynological as well as chronological studies of shallow‐water sediment cores and subaerial lake terraces. Reconstructed lake levels show an abrupt rise during glacial–interglacial terminations (MIS 6/5 and MIS 2/1) and during the MIS 4/3 stadial–interstadial transition. The most prominent lowstands occurred during glacial periods associated with a permanent lake‐ice cover (namely MIS 6, MIS 4 and MIS 2). Major triggering mechanisms of the lake‐level fluctuations at Lake El'gygytgyn are predominantly changes in air temperature and precipitation. Regional summer temperatures control the volume of meltwater supply as well as the duration of the lake‐ice cover (permanent or seasonal). The duration of the lake‐ice cover, in turn, enables or hampers near‐shore sediment transport, thus leading to long‐term lake‐level oscillations on glacial–interglacial time scales by blocking or opening the lake outflow, respectively. During periods of seasonal ice cover the lake level was additionally influenced by changes in precipitation. The discovered mechanism of climatologically driven level fluctuations of Lake El'gygytgyn are probably valid for large hydrologically open lakes in the Arctic in general, thus helping to understand arctic palaeohydrology and providing missing information for climate modelling.  相似文献   

Evolution of groundwater chemical composition under human activity in an oilfield   总被引：1，自引：0，他引：1  

A. P. Belousova  S. R. Krainov  B. N. Ryzhenko 《Environmental Geology》1999,38(1):34-46

 Analysis and hydrogeochemical modeling of hydrocarbonate groundwater, including its buffering geochemical properties, have demonstrated that this water has undergone a geochemical transformation almost throughout the whole of one industrial region. It is known that hydrocarbonate groundwater possesses a high protective natural geochemical potential, supporting neutralization of acid atmospheric precipitation. Natural hydrocarbonate water undergoes three stages of anthropogenic transformation caused by acid atmospheric precipitation over more than 50 years. The first stage is transformation of neutral hydrocarbonate water into alkaline water, accompanied by calcite precipitation and sodium carbonate dissolution from the unsaturated zone. The second stage is transformation of alkaline water into neutral hydrocarbonate water; the hydrocarbonate content, being less than the lower limit for background concentrations, showed reduced water buffering properties or protective potential relative to acid precipitation. The third stage is transformation of neutral hydrocarbonate water into acidic water, with a complete loss of protective geochemical potential. This unfavorable ecological situation with natural geochemically hydrocarbonate groundwater shows that natural groundwater less protected from the impact of acid atmospheric precipitation is in a worse ecological condition, which is confirmed by observations in northern and Western Europe and other regions of the world. Received: 30 October 1997 · Accepted: 23 March 1998  相似文献   

Coverage of Mars by Probes Slightly Off the Areostationary Orbit     

Elena Colella  Emiliano Ortore  Christian Circi  Ennio Condoleo 《Earth, Moon, and Planets》2017,120(1):31-39

This paper aims at investigating the feasibility of gaining complete and continuous coverage of an extended equatorial belt of Mars, under the effects of orbital perturbations. The problem could be solved by considering a minimum number of three probes, which move slightly off the Martian Areostationary Orbit. The proposed configurations allow the achievement of the goal without entailing corrective manoeuvres and presenting only a longitudinal motion with respect to the surface of Mars.  相似文献   

New sedimentological and palynological data from the Yarkand-Fergana Basin(Kyrgyz Tian Shan): Insights on its Mesozoic paleogeographic and tectonic evolution     

Julien Morin  Marc Jolivet  Dave Shaw  Sylvie Bourquin  Elena Bataleva 《地学前缘(英文版)》2021,12(1):183-202

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贝加尔湖的污染与富营养化     

Evgeniya N. Tarasov  Alexander A. Mamontov  Elena A. Mamontova 《湖泊科学》1998,10(S1):167-179

The long term systematic investigations of ion composition components (bicarbonates, chlorides, sulphates, magnesium, calcium, sodium, potassium) and trophic status components (suspension, chlorophyll-a, mineral and organic forms phosphorus and nitrogen, carbon, silica) of water from the lake proper, its tributaries and atmospheric precipitation, which make up the main share of substance supply in to the lake, as well as the Angara river, being the source of substance discharge allowed the lake recent state to be evaluated in terms of both chemical pollution and possible eutrophication of its water. The similar (in terms of river runojf) periods of 50-ies and 80-ies have been compared. It was revealed that as a result of industrial activity 409 thousand tons of mineral substances (27.2 thousand tons of chlorides, 162 thousand tons of sulphates and over 200 thousand tons of organic substances) are supplied in the lake annually. The supply of substances of the anthropogenic origin is higher for the South Baikal than that for the North and Middle Baikal (the sum of mineral substances in 3.6 times; sulphates in 5 times, organic substances, including hydrocarbons in 7 times).The absence of abundant phytoplankton in the period studied when the ratio of silica to phosphorus is optimum (over 100), as well as a revers correlation between winter nitrogen content and spring of chlorophyll-a concentration in the Baikal water and revers dependence between the suspension and chlorophyll-a along the Selenga river valley lead to the conclusion that Baikal water contains toxicants. It is verified by the presence of polychlorbiphenyls (PCB), poly-chlordibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) for the whole food web with the maximum PCDD/PCDF (TEQ to 175 P g · g^-1) concentration in the seal blubber. The levels are comparable with those reported for ringed seal (phoca hispida), living in the Baltic sea and Bar-row Strait Inlet in the Canadian Arctic.  相似文献   

Contribution to knowledge regarding the sources of earthquakes on the island of Ischia (Southern Italy)     

Cubellis  Elena  Luongo  Giuseppe  Obrizzo  Francesco  Sepe  Vincenzo  Tammaro  Umberto 《Natural Hazards》2020,100(3):955-994

Natural Hazards - This paper analyses data regarding the seismicity and ground deformations of the island of Ischia. The goal is to describe these phenomena as a space–time process, exploring...  相似文献   

The Lu–Hf Isotope Composition of Zircon from Syenites of the Saharjok Alkaline Massif,Kola Peninsula     

Vetrin  V. R.  Belousova  E. A. 《Geology of Ore Deposits》2020,62(7):574-583

Geology of Ore Deposits - Zircon crystals from the alkaline and nepheline syenites of the Saharjok massif, which were formed during the magmatic (2645 ± 7 Ma), hydrothermal (1832 ± 7 Ma),...  相似文献   

Sedimentary iron inputs stimulate seagrass (Posidonia oceanica) population growth in carbonate sediments     

Núria Marbà  Carlos M. Duarte  Marianne Holmer  Maria Ll. Calleja  Elvira Álvarez  Elena Díaz-Almela  Neus Garcias-Bonet 《Estuarine, Coastal and Shelf Science》2008

The relationship between sedimentary Fe inputs and net seagrass population growth across a range of Posidonia oceanica meadows growing in carbonate Mediterranean sediments (Balearic Islands, Spain; SE Iberian Peninsula, Spain; Limassol, Cyprus; Sounion, Greece) was examined using comparative analysis. Sedimentary Fe inputs were measured using benthic sediment traps and the net population growth of P. oceanica meadows was assessed using direct census of tagged plants. The meadows examined ranged from meadows undergoing a severe decline to expanding meadows (specific net population growth, from −0.14 yr⁻¹ to 0.05 yr⁻¹). Similarly, Fe inputs to the meadows ranged almost an order of magnitude across meadows (8.6–69.1 mg Fe m⁻² d⁻¹). There was a significant, positive relationship between sedimentary iron inputs and seagrass net population growth, accounting for 36% of the variability in population growth across meadows. The relationship obtained suggested that seagrass meadows receiving Fe inputs below 43 mg Fe m⁻² d⁻¹ are vulnerable and in risk of decline, confirming the pivotal role of Fe in the control of growth and the stability of seagrass meadows in carbonate sediments.  相似文献   

Microbially mediated methane and sulfur cycling in pockmark sediments of the Gdansk Basin, Baltic Sea   总被引：2，自引：2，他引：0  

Nikolay V. Pimenov  Marina O. Ulyanova  Timur A. Kanapatsky  Elena F. Veslopolova  Pavel A. Sigalevich  Vadim V. Sivkov 《Geo-Marine Letters》2010,30(3-4):439-448

In the Russian sector of the Gdansk Basin (Baltic Sea), high organic matter influx fuels microbial processes resulting in the formation of reduced sediments with elevated methane concentrations. Investigated areas of geoacoustic anomalies (～245 km²) were found to contain three distinct geomorphologic structures (pockmarks), with a total area of ～1 km². Methane anomalies recorded in the water above one of these pockmarks were traced as high as 10 m above the bottom. In pockmark sediments, sulfate reduction and anaerobic oxidation of methane (AOM) occurred at high rates of 33 and 50 µmol dm^?3 day^?1, respectively. Integrated over 0–180 cm sediment depths, AOM exceeded methanogenesis almost tenfold. High AOM rates resulted from methane influx from deeper sediment layers. The δ¹³C signature of methane carbon (?78.1 to ?71.1‰) indicates the biogenic origin of pockmark methane. In pockmark sediments, up to 70% of reduced sulfur compounds was possibly produced via AOM.  相似文献