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   

Early Weichselian (MIS 5d and 5c) temperatures and environmental changes in northern Fennoscandia as recorded by chironomids and macroremains at Sokli,northeast Finland     

STEFAN ENGELS  KARIN F. HELMENS  MINNA VÄLIRANTA  STEPHEN J. BROOKS  H. JOHN B. BIRKS 《Boreas: An International Journal of Quaternary Research》2010,39(4):689-704

Engels, S., Helmens, K. F., Väliranta, M., Brooks, S. J. & Birks, H. J. B. 2010: Early Weichselian (MIS 5d and 5c) temperatures and environmental changes in northern Fennoscandia as recorded by chironomids and macroremains at Sokli, northeast Finland. Boreas, Vol. 39, pp. 689–704. 10.1111/j.1502‐3885.2010.00163.x. ISSN 0300‐9483. A 25‐m‐long sediment record spanning the time from the Eemian to the Holocene was recovered from Sokli, northeast Finland. This study focuses on a 6‐m‐long sediment interval that is dated to the Early Weichselian period (MIS 5d and 5c) and consists of lacustrine and fluvial deposits. Using chironomid remains, botanical and zoological macroremains as well as sediment lithology, we were able to reconstruct past changes in the environment, including climate. The results indicate that the site was situated on a flood‐plain during the latter stages of MIS 5d (Herning Stadial) and that summer temperatures might have been ～6 °C lower than at present. Although this value should be treated with caution, as numerical analysis shows that it has a very poor fit‐to‐temperature, this low reconstructed value concurs with several other reconstructions that are available from western Europe. During MIS 5c (Brørup interstadial), the depositional environment changed into a lake system, initially with stratification of the water and subsequently with complete mixing and a strong influence of streams. Both chironomid‐based and macroremain‐based temperature inferences indicate past July air temperatures that were significantly higher than at present. This result is in contrast to other (low‐resolution) reconstructions from northern Fennoscandia that indicate past temperatures 6–7 °C lower than present using fossil coleopteran assemblages. However, several central European sites indicate that there was a phase during the Brørup interstadial that was characterized by high summer temperatures, and a comparison between the high‐resolution reconstructions from western Europe and the results presented in this study suggests that the north–south July air temperature gradient between the mid‐ and high‐latitudes was much weaker during the Brørup interstadial than it is at present. High solar insolation values (particularly the obliquity) during the Brørup interstadial might explain the low summer temperature gradient over the European continent. A return to fluvial conditions occurred in the upper parts of the sediment sequence, and, after a brief interval of gyttja deposition under cooling conditions, the site became glaciated during MIS 5b.  相似文献   

Late‐Quaternary palaeoclimatic research in Fennoscandia – A historical review     

H. JOHN B. BIRKS  HEIKKI SEPPÄ 《Boreas: An International Journal of Quaternary Research》2010,39(4):655-673

Birks, H. J. B. & Seppä, H. 2010: Late‐Quaternary palaeoclimatic research in Fennoscandia – A historical review. Boreas, Vol. 39, pp. 655–673. 10.1111/j.1502‐3885.2010.00160.x. ISSN 0300‐9483. Ideas and understanding of Late‐Quaternary climatic history, especially in the Lateglacial and the postglacial, were initiated in Fennoscandia in the 19th century with pioneering studies on peat stratigraphy, megafossils and macrofossils. This review traces the history of palaeoclimatic research and the development of current ideas about climatic changes, with particular reference to the Lateglacial and its rapid climatic fluctuations, such as the Younger Dryas period, and to the Holocene, with its thermal maximum and shifts in precipitation.  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   

A Reconnaisance Study of Phase Boundaries in Low-Alkali Basaltic Liquids   总被引：1，自引：1，他引：1  

LONGHI  JOHN; PAN  VIVIAN 《Journal of Petrology》1988,29(1):115-147

New data, derived from microprobe analyses of melting experiments,are presented in the form of sub-projections in the model basaltsystem, Ol-Pl-Wo-SiO₂, to illustrate the shifts in the liquidusfields of olivine, plagioclase, spinel, pyroxene, and silicain low-alkali liquids as functions of variable Wo componentand Mg. The projections are calculated in terms of oxygen unitsto avoid the ‘non conservative’ properties of moleunits and to provide a better representation of the volume proportionsof minerals. These projections show that over a wide range ofcomposition the complex, natural basalt system has liquidusboundaries that resemble many of those in the simpler CaO-MgO-Al₂O₃-SiO₂system. One important feature of the natural system is the progressivechange in the dominant low-Ca pyroxene along the olivine liquidussurface from protoenstatite to orthoenstatite to pigeonite asMg decreases. Another notable feature is the expansion of theplagioclase liquid field at the expense of the olivine and low-Capyroxene fields as Mg decreases in low-alkali liquids. Increasingalkali concentration has almost exactly the opposite effectso that evolved terrestrial basalts have higher proportionsof feldspar components than their lunar and eucritic counterparts. The new phase diagrams indicate that low-alkali liquids residualto those that produced the ancient, ferroan lunar anorthositesshould have crystallized an amount of ferro-quartz-gabbro equivalentto 10 per cent of the volumes of their parents. The scarcityof such rocks among the returned lunar samples poses a problemfor simple models of lunar petrogenesis.  相似文献   

Textural and geochemical alternations in Late Cenozoic Bahamian dolomites     

JOHN M. DAWANS  PETER K. SWART 《Sedimentology》1988,35(3):385-403

Dolomitized intervals of a core from San Salvador Island, Bahamas, exhibit variations of two texturally and geochemically distinct end-members. In the Pliocene section of the dolomitized interval, the two end-members alternate in a pattern that may reflect originally and/or diagenetically modified depositional facies. Formerly mud-free intervals, locally capped by exposure surfaces are massive crystalline, mimetic dolomites (CM). Muddier sediments are replaced by friable microsucrosic dolomites (MS). CM and MS dolomites also differ in porosity (< 10% vs > 30%), permeability (< 10 md vs > 100 md), mol% MgCO₃ (44–9 vs 47–7) mol%), oxygen isotopic composition (1–7 vs 2–7‰) and strontium content (241 vs 106 ppm). These data indicate that depositional and diagenetic fabric are the principal controls governing the distribution of dolomite types. Differences in texture and geochemistry are suggested as arising through differential rates of crystallization produced as a result of variations in permeability and reactivity of the precursor sediments and rocks.  相似文献   

Faceted garnets from sandstones of the Munising Formation (Cambrian), northern Michigan: petrographic evidence for their origin by intrastratal dissolution     

JOHN F. SALVINO  MICHAEL ANTHONY VELBEL 《Sedimentology》1989,36(2):371-379

Imbricate wedge marks (facets) on garnets in sandstones of the Cambrian Munising Formation of northern Michigan are associated with mouldic secondary porosity developed at the expense of garnet. Mouldic pores surrounding faceted garnets indicate that garnets in these sandstones have been affected by intrastratal dissolution (retreat of the mineral surface from its original boundaries) rather than by grain enlargement, which would be expected if garnet overgrowths had formed. The association of garnet facets with textural evidence of garnet dissolution proves that garnet facets form by intrastratal dissolution. These results confirm similar findings in other recent studies, and extend the geographic and stratigraphic range of proven occurrences of facet formation by intrastratal dissolution.  相似文献   

The Scots Bay formation, Nova Scotia, Canada, a Jurassic carbonate lake with Silica-rich hydrothermal springs   总被引：1，自引：0，他引：1  

CAROL C. BIRNEY De  WET JOHN F. HUBERT† 《Sedimentology》1989,36(5):857-873

During Early Jurassic time, the Scots Bay Formation accumulated in an aerobic lake on the floor of the subtropical Fundy rift valley. A diverse biota flourished in the lake as evidenced by algal stromatolites, oncolites, charophytes, ostracods, gastropods, conchostracans, fish bones, calcispheres and logs. Carbonate wackestone and packstone were deposited in the littoral zone and lime mudstone accumulated offshore on a proximal slope. Silica-rich hydrothermal springs and seeps around and on the floor of the lake precipitated siliceous tufa and silicified adjacent carbonate strata. The tufa is characterized by the progressive sequence: (1) open-framework, porous substrate of goethite spheres, (2) encrusting chalcedony spherulites where goethite inclusions decrease in size and number outwards towards the surfaces of the spherulites, (3) a fringe of quartz on the chalcedony spherulites and (4) coarsening inwards mosaics of quartz that filled the remaining voids. Carbonate diagenesis included conversion of low-Mg calcite ooze to micrite and microspar-pseudospar, and local dissolution and reprecipitation of calcite cement. At times the lake shrank in size, concentrating silica in increasingly alkaline lake water which then silicified some of the carbonate strata and logs. The latest cements were calcite, zeolites and celadonite.  相似文献   

The Geochemistry and Experimental Petrology of Sodic Alkaline Basalts from Oatlands, Tasmania   总被引：2，自引：2，他引：2  

ADAM  JOHN 《Journal of Petrology》1990,31(6):1201-1223

Sodic basalts of Oligocene-Early Micene age occur within anEarly Tertiary graben in the Oatlands district of Tasmania.They include olivine tholeiites, alkali olivine basalts, basanites,transitional nephelinites, nepheline hawaiites, and nephelinemugearites. They have compositional characteristics in commonwith sodic alkaline basalt suites from other parts of the world.With decreasing SiO₂, concentrations of CaO, alkalis, P₂O₅,and incompatible trace elements increase. Compositional and experimental data for the basalts are consistentwith their derivation by polybaric partial melting of a garnetlherzolite source enriched in P₂O₅, light rare earths, Nb, andother incompatible trace elements. Experimental data for a primitivenepheline basanite from the Oatlands district indicate thatconcentrations of H₂O+CO₂ need not have been more than 6?5 wt.%for the original basanite magma to have derived from an amphibole-bearinggarnet lherzolite source. In the case of more SiO₂-undersaturatedolivine melilitites from the neighbouring Central Plateau, theexperimental evidence is consistent with either higher concentrationsof H₂O+CO₂ (approaching 14 wt.%), or higher pressures of origin(>35 kb). Petrographic and geochemical evidence suggeststhat the latter is the more probable of the alternatives.  相似文献   

The origin and significance of groundwater-seepage gypsum from Bristol Dry Lake, California, USA     

MICHAEL R. ROSEN  JOHN K. WARREN† 《Sedimentology》1990,37(6):983-996

Gypsum and anhydrite fabrics observed in trenches and deep (500 m) cores from Bristol Dry Lake, California, USA, exhibit a vertical alignment of crystals similar to the fabric seen in bottom-nucleated brine pond gypsum. However, geochemical and sedimentological evidence indicate that the gypsum formed in Bristol Dry Lake precipitated displacively within the sediment where groundwater saturated with respect to gypsum recharges around the playa margin (groundwater-seepage gypsum). Evidence for displacive growth of gypsum is: (i) the geometry of the deposit, (ii) stable isotopic data and the water chemistry of the brine, and (iii) inclusions of matrix which follow twin planes and completely surround crystals as they grow. The bulk of the gypsum precipitated in the playa occurs around the edges of the playa in the playamargin facies and completely rings the lake. Sulphate concentrations in the groundwater increase toward the gypsum zone in the playa margin. Basinward of this zone, sulphate concentrations decrease sharply to trace element levels in the basin centre brine. Authigenic gypsum is rare in the centre of the playa. Stable (δ¹⁸O values measured for gypsum waters of crystallization (GWC) are similar to the values calculated for groundwater in the playa margin and alluvial fan sediments (?– 6%0), whereas measured brine δ¹⁸O values range from + 0·5 to + 3·7%0. Deuterium values measured for groundwater are ?– 70%0, GWC are ?– 60 to – 65%0 and brine values are ?– 57%0. The geometry of the deposit and the chemical data suggest that the water precipitating the gypsum is more closely associated with the groundwater than the brine. However, some mixing between groundwater and brine is likely. Within 100 m of the surface, the gypsum dehydrates to anhydrite, although the same vertically aligned fabric is retained through the diagenetic process. The similarity of displacive vertically aligned gypsum and anhydrite fabrics seen in Bristol Dry Lake to subaqueously deposited gypsum in modern brine ponds indicates that the criteria used to define subaqueous fabrics must be better constrained.  相似文献