Determination of the effect of surface water irrigation on the groundwater chemistry of a hard rock terrain in central India     

L. P. CHOURASIA  JOHN H. TELLAM 《水文科学杂志》2013,58(4):313-328

Abstract

The Bundelkhand area of central India consists of weathered granitic bedrock. The aim of the present study was to identify the effects of surface water irrigation on groundwater quality in shallow aquifers used for domestic supply. A set of 37, 58 and 17 samples were collected, respectively, from the non-irrigated area, the irrigated area and surface waters. Concentrations of major ions (including NO₃ ^?), PO₄ = and Fe⁺⁺ were determined. A statistical comparison of the data groups was carried out assuming that the only difference between the two areas was in agricultural practice. It was discovered that, despite the better quality of the surface waters, the irrigated area groundwaters were higher in concentration than those of the non-irrigated area. The main causes for that appear to be evaporation/transpiration and fertilizer application, modified by calcite precipitation and ion exchange. The proposed approach is simple enough to be used routinely in monitoring.  相似文献   

Developing a modern pollen–climate calibration data set for Norway     

ANNE E. BJUNE  H. JOHN B. BIRKS  SYLVIA M. PEGLAR  ARVID ODLAND 《Boreas: An International Journal of Quaternary Research》2010,39(4):674-688

Bjune, A. E., Birks, H. J. B., Peglar, S. M. & Odland, A. 2010: Developing a modern pollen–climate calibration data set for Norway. Boreas, Vol. 39, pp. 674–688. 10.1111/j.1502‐3885.2010.00158.x. ISSN 0300‐9483. Modern pollen–climate data sets consisting of modern pollen assemblages and modern climate data (mean July temperature and mean annual precipitation) have been developed for Norway based on 191 lakes and 321 lakes. The original 191‐lake data set was designed to optimize the distribution of the lakes sampled along the mean July temperature gradient, thereby fulfilling one of the most critical assumptions of weighted‐averaging regression and calibration and its relative, weighted‐averaging partial least‐squares regression. A further 130 surface samples of comparable taphonomy, taxonomic detail and analyst became available as a result of other projects. These 130 samples, all from new lakes, were added to the 191‐lake data set to create the 321‐lake data set. The collection and construction of these data sets are outlined. Numerical analyses involving generalized linear modelling, constrained ordination techniques, weighted‐averaging partial least‐squares regression, and two different cross‐validation procedures are used to asses the effects of increasing the size of the calibration data set from 191 to 321 lakes. The two data sets are used to reconstruct mean July temperature and mean annual precipitation for a Holocene site in northwest Norway and a Lateglacial site in west‐central Norway. Overall, little is to be gained by increasing the modern data set beyond about 200 lakes in terms of modern model performance statistics, but the down‐core reconstructions show less between‐sample variability and are thus potentially more plausible and realistic when based on the 321‐lake data set.  相似文献   

Towards a world hydrological cycle observing system     

JOHN C. RODDA  SERGE A. PIEYNS  NAGINDER S. SEHMI  GEOFFREY MATTHEWS 《水文科学杂志》2013,58(5):373-378

Abstract

There are considerable difficulties in assembling global hydrological data sets in near real time, data that might be used for deciding investment for sustainable water resources development and management, for environmental protection and for studying global change. Several reasons exist for these difficulties, a new one is that many countries have recently been cutting back on hydrological networks and the services that operate them. This means that knowledge of the World's water resources is getting worse when the global demand for water is accelerating. By way of contrast, meteorologists have ready access to large volumes of global data, much of it in real time, principally through WMO's World Weather Watch (WWW). A World Hydrological Cycle Observing System (WHYCOS) is proposed to facilitate access to global data and support hydrological services in need. A world-wide network of about 1000 stations is planned for the largest rivers, together with associated data bases and products to meet the needs of users. WHYCOS would start in Africa with a 100-station network and be expanded to other regions. It is a necessary tool for averting the coming water crisis and essential to the drive towards sustainable development.  相似文献   

Lateglacial vegetation and palaeoenvironment in W Norway,with new pollen data from the Sunnmøre region     

LINN CECILIE KRÜGER  AAGE PAUS  JOHN INGE SVENDSEN  ANNE E. BJUNE 《Boreas: An International Journal of Quaternary Research》2011,40(4):616-635

Krüger, L. C., Paus, A., Svendsen, J. I. & Bjune, A. E. 2011: Lateglacial vegetation and palaeoenvironment in W Norway, with new pollen data from the Sunnmøre region. Boreas, 10.1111/j.1502‐3885.2011.00213.x. ISSN 0300‐9483. Two sediment sequences from Sunnmøre, northern W Norway, were pollen‐analytically studied to reconstruct the Lateglacial vegetation history and climate. The coastal Dimnamyra was deglaciated around 15.3 ka BP, whereas Løkjingsmyra, further inland, became ice‐free around 14 ka BP. The pioneer vegetation dominated by snow‐bed communities was gradually replaced by grassland and sparse heath vegetation. A pronounced peak in Poaceae around 12.9 ka BP may reflect warmer and/or drier conditions. The Younger Dryas (YD) cooling phase shows increasing snow‐bed vegetation and the local establishment of Artemisia norvegica. A subsequent vegetation closure from grassland to heath signals the Holocene warming. Birch forests were established 500–600 years after the YD–Holocene transition. This development follows the pattern of the Sunnmøre region, which is clearly different from the Empetrum dominance in the Lateglacial interstadial further south in W Norway. The Lateglacial oscillations GI‐1d (Older Dryas) and GI‐1b (Gerzensee) are hardly traceable in the north, in contrast to southern W Norway. The southern vegetation was probably closer to an ecotone and more susceptible to climate changes.  相似文献   

ENDOLITHIC LICHENS,RAPID BIOLOGICAL WEATHERING AND SCHMIDT HAMMER R‐VALUES ON RECENTLY EXPOSED ROCK SURFACES: STORBREEN GLACIER FORELAND,JOTUNHEIMEN, NORWAY     

JOHN A. MATTHEWS  GERAINT OWEN 《Geografiska Annaler: Series A, Physical Geography》2008,90(4):287-297

The endolithic lichen Lecidea auriculata is known to enhance rock surface weathering on the Little Ice Age moraines of the glacier Storbreen in Jotunheimen, central southern Norway. This study demonstrates the reduction in Schmidt hammer Rvalues that followed the rapid colonization by this lichen of pyroxene‐granulite boulders on terrain deglaciated over the last 88 years. In the absence of this lichen, the characteristic mean R‐value of boulder surfaces is 61.0 ± 0.3; where this lichen is present, R‐values are lower by at least 20 units on surfaces exposed for 30–40 years. A similar reduction in rock hardness on rock surfaces without a lichen cover requires about 10 ka. The rapid initial weakening of the rock surfaces is indicative of rates of biological weathering by endolithic lichens that may be two orders of magnitude (200–300 times) faster than rates of physico‐chemical weathering alone. If not avoided, the effects of this type of lichen are likely to negate the effectiveness of the Schmidt hammer and other methods for exposure‐age dating, including cosmogenic‐nuclide dating, in severe alpine and polar periglacial environments. The results also suggest a new method for dating rock surfaces exposed for <50 years.  相似文献   

The British Geological Survey: the first 150 years     

JOHN C. THACKRAY 《Geology Today》1985,1(6):183-183

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Morphology, geology and oceanography of the Hinlopen Strait and Trough, Svalbard, Norway     

STEPHANIE PFIRMAN  JOHN D. MILLIMAN 《Polar research》1987,5(3):297-298

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The latest on … the Brent Delta     

JOHN H. McD. WHITAKER 《Geology Today》1990,6(5):159-162

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>A-level fieldwork guide: Charnwood Forest     

JOHN B. MOSELEY 《Geology Today》1998,14(5):195-198

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The Holocene fossil marine macrofauna of the Vestfold Hills, East Antarctica     

JOHN PICKARD 《Boreas: An International Journal of Quaternary Research》1985,14(2):189-202

The Holocene (< 10,000 years old) fossil marine macrofauna (molluscs, polychaetes, mammals and birds) of the Vestfold Hills, Antarctica (68°30'S, 78°00'E) is described. All species are extant, with circumantarctic or wider distributions and wide depth ranges. At Heidemann Bay, Pleistocene-age (> 30 ky old) shell fragments occur in a Holocene moraine. These are interpreted as being glacially reworked fossil shells. Holocene benthic estuarine and coastal molluses and serpulid worm tubes are abundant on the flanks of terraces above saline and hypersaline lakes. Extensive radiocarbon dating gives a chronology of these deposits which were not synchronous. Mummies of seals and penguins, which are concentrated on the shores of the saline lakes and scattered across the Hills, are of no use in dating geomorphological events. Marine fossils in moraines are difficult to interpret because they can be glacially-transported live or fossil shells, or deposited after wind transport. The fossil fauna has such a wide ecological range that it indicates only in general terms that for part of the Pleistocene and most of the Holocene, climatic conditions were broadly similar to the present.  相似文献