Age and origin of groundwater resources in the Ararat Valley,Armenia: a baseline study applying hydrogeochemistry and environmental tracers     

Schubert  Michael  Michelsen  Nils  Schmidt  Axel  Eichenauer  Laura  Knoeller  Kay  Arakelyan  Alexander  Harutyunyan  Lilith  Schüth  Christoph 《Hydrogeology Journal》2021,29(7):2517-2527

Within the Ararat Valley (Armenia), a continuously growing water demand (for irrigation and fish farming) and a simultaneous decline in groundwater recharge (due to climate change) result in increasing stress on the local groundwater resources. This detrimental development is reflected by groundwater-level drops and an associated reduction of the area with artesian conditions in the valley centre. This situation calls for increasing efforts aimed at more sustainable water resources management. The aim of this baseline study was the collection of data that allows for study on the origin and age distribution of the Ararat Valley groundwater based on environmental tracers, namely stable (δ²H, δ¹⁸O) and radioactive (³⁵S, ³H) isotopes, as well as physical-chemical indicators. The results show that the Ararat Valley receives modern recharge, despite its (semi-)arid climate. While subannual groundwater residence times could be disproved (³⁵S), the detected ³H pattern suggests groundwater ages of several decades, with the oldest waters being recharged around 60 years ago. The differing groundwater ages are reflected by varying scatter of stable isotope and hydrochemical signatures. The presence of young groundwater (i.e., younger that the 1970s), some containing nitrate, indicates groundwater vulnerability and underscores the importance of increased efforts to achieve sustainable management of this natural resource. Since stable isotope signatures indicate the recharge areas to be located in the mountains surrounding the valley, these efforts must not be limited to the central part of the valley where most of the abstraction wells are located.

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High-frequency climate oscillations drive ice-off variability for Northern Hemisphere lakes and rivers     

Schmidt  Daniel F.  Grise  Kevin M.  Pace  Michael L. 《Climatic change》2019,152(3-4):517-532

Climatic Change - This study examines the climatic drivers of ice-off dates for lakes and rivers across the Northern Hemisphere. Most lakes and rivers have trended toward earlier ice-off dates over...  相似文献   

North Atlantic climate impact on early late‐glacial climate oscillations in the south‐eastern Alps inferred from a multi‐proxy lake sediment record     

Roland Schmidt  Kaarina Weckström  Stefan Lauterbach  Richard Tessadri  Kerstin Huber 《第四纪科学杂志》2012,27(1):40-50

High‐resolution multi‐proxy analyses of a sediment core section from Lake Jeserzersee (Saissersee) in the piedmont lobe of the Würmian Drau glacier (Carinthia, Austria) reveal pronounced climatic oscillations during the early late glacial (ca. 18.5–16.0k cal a BP). Diatom‐inferred epilimnetic summer water temperatures show a close correspondence with temperature reconstructions from the adjacent Lake Längsee record and, on a hemispheric scale, with fluctuations of ice‐rafted debris in the North Atlantic. This suggests that North Atlantic climate triggered summer climate variability in the Alps during the early late glacial. The expansion of pine (mainly dwarf pine) between ca. 18.5 and 18.1k cal a BP indicates warming during the so‐called ‘Längsee oscillation’. The subsequent stepwise climate deterioration between ca. 18.1 and 17.6k cal a BP culminated in a tripartite cold period between ca. 17.6 and 16.9k cal a BP with diatom‐inferred summer water temperatures 8.5–10 °C below modern values and a shift from wet to dry conditions. This period probably coincides with a major Alpine glacier advance termed the Gschnitz stadial. A warmer interval between ca. 16.9 and 16.4k cal a BP separates this cold phase from a second, shorter and less pronounced cold phase between ca. 16.4 and 16.0k cal a BP, which is thought to correlate with the Clavadel/Senders glacier advance in the Alps. The following temperature increase, coupled with wet (probably snow‐rich) conditions, caused the expansion of birch during the transition period to the late glacial interstadial. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Zur Anwendung des Standards TGL 27885/01 zur Klassifizierung und Bewirtschaftung von Flachgewässern     

I. Schmidt 《洁净——土壤、空气、水》1988,16(3):281-292

For the shallow lake there can be expected eutrophic conditions according to its morphometric data (z? 2.8 m, l 1.1… 1.8a), even mesotrophic conditions acc. to the catchment area (2.8 km²/hm³, 8 km²/km², 20% wood) and eutrophic conditions acc. to load (1,340 Population Equivalents/hm³, 0.027… 0.386 g/m² a P). The actually measured data of oxygen balance, nutrient contents and bioproduction show a eutrophic situation with a trend towards polytrophy. The difference to the expectation values can be explained by an underestimation of direct loading from a duck farm and the back-wash waters of a waterworks, so that sanitation measures for reducing the direct loading are promising. The relocation of the duck farm and of a large complex of stables as well as the introduction of extensive fishery utilization with a balanced stock of predatory fish resulted in perceptible trends of oligotrophication already after two years, especially by a remarkable promotion of the macrophyte stocks in the shallow water zone.  相似文献   

Diatomeen-, pollen- und sedimentmikrostratigraphische Untersuchungen zur anthropogenen Beeinflussung des Höllerer Sees (Oberösterreich)     

Roland Schmidt  Heikki Simola 《Aquatic Sciences - Research Across Boundaries》1991,53(1):74-89

A profundal sediment core from Höllerer See frozen in situ was studied by means of diatom, microstratigraphical tape peel and pollen analyses. Varved sequences reflect eutrophication during mediaeval settlement and according to varve counts a recent eutrophic phase since the 1970's. Mesotrophication in-between coincides with regrowth of forests near the lake.

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An overview of chromium in the marine environment     

Dr. Claus-Dieter Geisler  Dr. Diether Schmidt 《Ocean Dynamics》1991,44(4):185-196

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An intercomparison of seawater filtration procedures     

J.M. Bewers  P.A. Yeats  S. Westerlund  B. Magnusson  D. Schmidt  H. Zehle  S.S. Berman  A. Mykytiuk  J.C. Duinker  R.F. Nolting  R.G. Smith  H.L. Windom 《Marine pollution bulletin》1985,16(7):277-281

Filtration systems, used for the preparation of coastal seawater samples for trace analysis, have been intercompared to determine the extent of contamination arising during the filtration process. The results show that all the systems intercompared are able to provide uncontaminated filtrates for copper, nickel, cobalt and manganese and, with two exceptions, for cadmium and iron, at levels that would be encountered in uncontaminated coastal waters.  相似文献   

Trace gas measurements during aircraft flights in the tropopause region over Europe and North Africa     

M. Schmidt  R. Borchers  P. Fabian  G. Flentje  W. A. Matthews  A. Szabo  S. Lal 《Journal of Atmospheric Chemistry》1984,2(2):133-143

During aircraft flights in May 1981 from Munich (40°N) to north of the Spitsbergen Islands (82°N) and to Monrovia, Liberia (6°N), air samples were obtained in the altitude range of 8 to 11 km and during the ascents and descents near the airports. These samples have been analyzed for the trace gas mixing ratios of CH₄, CO and N₂O. The results of these analyses are presented and discussed.The results provide new evidence of tropospheric-stratospheric exchange events in the vicinity of the subpolar and subtropical tropopause foldings and possibly show a case of transport of CO-enriched air in the upper troposphere above the North Atlantic Ocean.  相似文献   

The southern agglomeration zone of the GDR — Regional structure and development     

K. Scherf Dr.  H. Schmidt Dr. 《GeoJournal》1984,8(1):33-44

Agglomeration areas in the GDR are those regions, which are characterized by an above average level of regional concentration of productive forces and their conditions of reproduction. The economic potential concentrated in these regions represents a large part of the national economy. It is possible to describe the territorial structure of these agglomeration areas by general indices (agglomeration core — agglomeration field — agglometation fringe; polycentric node-band-structure), but also the individual features of each one of these regions are to be attended. They are expressed for the first time by several forms of localization of plants and by the structure of settlements and settlement networks. The present main tendencies in the development of the agglomeration regions are:

They succeeded in minimizing the regional disparities of productivity between different agglomeration regions and within them, and in stabilizing the economic position of these regions by systematic measures for investment and rationalization and the hereby influenced structural changes.

At present and up to 1990 the completion of housing programme is of foremost importance by which the main activities will shift from the urban fringe to the centres of the cities; provincial towns and smaller settlements will also participate in this programme.

The main target of these activities is to remove imperfect structures and other burning problems of the agglomeration regions step by step. Geographical Institutes are dealing with the management of these tasks too.  相似文献   

Possible influences of solar radiation variations on the atmospheric circulation in the northern hemisphere of the earth     

Manfred Schmidt 《Climatic change》1986,8(3):279-294

The strength of the circumpolar zonal circulation of the atmosphere in the northern hemisphere, expressed by an index calculated from the air pressure gradient between 35° N and 65°N, shows a remarkable secular change in this century in the years 1935 to 1938, and probably again in the years after 1970. A contemporary change and parallel course with a high positive correlation can be found in a solar radiation index calculated by means of sunspot numbers and solar faculae areas. A good correlation was also found between this solar radiation index and a series of UV measurements on Mt. Wilson. The possible mechanism of action in the atmosphere will be discussed, and it is shown that this solar radiation index is also correlated with circulation parameters in the troposphere and stratosphere over Europe. There are indications of a decrease of the action from the upper to the lower atmosphere. The consequences of this secular change of circulation for the climatic history in the 20th century in Europe are presented and from that a hypothetical retrospective view of the European climatic history before the 20th century, based on the total series of sunspot numbers, is briefly discussed. In a general view with smoothed data it can be concluded that the sun seems to determine the basic structure of the north hemispheric circulation in middle latitudes, if a strong influence of sunspots and solar faculae on the solar radiation is assumed.  相似文献