The Winnipeg Formation is the basal sedimentary unit throughout much of southern and central Manitoba, Canada, where it forms
a regional aquifer over most of its extent. This aquifer is an important source of water in southeastern Manitoba and in Manitoba’s
Interlake area, but in most other areas, groundwater within the aquifer is saline. Chemical and isotopic evidence indicate
the presence of groundwaters of three different origins: (1) basin brines; (2) modern meteoric recharge; and (3) subglacial
recharge that occurred during the late Pleistocene. Hydraulic head and sedimentary facies distributions indicate that the
flow system in parts of the area is not in a state of equilibrium and saline waters will encroach on areas currently occupied
by freshwater in some areas, while in other areas, freshwater will replace saline water. These features must be considered
in groundwater resource management, as groundwater withdrawals will likely hasten these processes.
Resumen La Formación Winnipeg es la unidad sedimentaria basal en la mayor parte de Manitoba central, Canadá, donde forma un acuífero
regional en la mayor parte de su extensión. Este acuífero es una fuente importante de agua en el Sureste de Manitoba y el
área de entrelagos de Manitoba, pero en la mayoría de las otras zonas del acuífero, el agua es salina. Las evidencias químicas
e isotópicas indican que existen aguas subterráneas de tres orígenes diferentes: (1) salmueras de cuenca; (2) recarga meteórica
actual; y (3) recarga subglacial ocurrida durante el Pleistoceno Superior. Los niveles piezométricos y la distribución de
las facies sedimentarias indican que el sistema de flujo no se encuentra en estado de equilibrio en parte del área y las aguas
salinas irán invadiendo áreas actualmente ocupadas con aguas dulces, mientras que en otras zonas el agua dulce está reemplazando
al agua salina. Estos hechos deben ser considerados en la gestión de las aguas subterráneas como recurso, ya que las extracciones
de agua acelerarán probablemente estos procesos.
Résumé La Formation de Winnipeg est l’unité sédimentaire de base sur la plus grande partie du Sud et du centre du Manitoba au Canada,
où elle forme un aquifère régional sur pratiquement toute son extension. Cet aquifère représente une ressource en eau importante
dans le Sud-Est du Manitoba et dans les zones d’entre les lacs, mais salée dans la plus part des autres zones. Les indications
isotopiques et chimiques permettent de distinguer trois différentes origines des eaux souterraines: (1) les saumures de bassin;
(2) la recharge météoritique moderne; (3) la recharge sub-glaciaire qui est apparue durant le Pléistocène récent. Les charges
hydrauliques et la distribution des faciès sédimentaires indiquent que le système d’écoulement dans certaines zones n’est
pas dans un état d’équilibre et que les eaux salées empièteront sur des zones d’eau douce, tandis que dans d’autres zones
l’eau douce remplacera les eaux salées. Ces aspects doivent être considérés dans la gestion des ressources en eau souterraine,
car le prélèvement des eaux souterraines pourrait accentuer ces processus.
Springs in karstic carbonate rocks frequently carry a sediment load as well as a dissolved load. Analysis of morphology and
mineralogy of suspended sediment from three contrasting karst springs reveals a suite of clastic particles that reflect both
source areas and processes that take place within the aquifer. Nolte Spring in Lancaster County, Pennsylvania, USA, discharges
sediment of apparently precipitated calcite, indicating that at some point in the aquifer or vadose zone, water exceeds saturation
with respect to calcite. Sediment morphologies and chemical conditions in the aquifer point to two different scenarios for
this precipitation. The other two springs, Arch Spring in Blair County, Pennsylvania and Bushkill Spring in Northampton County,
Pennsylvania, show no evidence of calcite precipitation. Arch Spring discharges mainly layer silicates, while Bushkill Spring
discharges mainly silica.
Resumen Los manantiales en rocas carbonatadas karstficadas tienen frecuentemente una carga de sedimentos y de sólidos disueltos. Los
análisis de la morfología y mineralogía de los sedimentos suspendidos de tres manantiales kársticos contrastados revela un
conjunto de partículas clásticas que reflejan ambas áreas fuente y los procesos que tienen lugar dentro del acuífero. Nolte
Spring en el Condado de Lancaster, Pennsylvania, USA, descarga sedimento de calcita aparentemente precipitada indicando que
en cierto punto del acuífero o en la zona vadosa, el agua supera la saturación con respecto a la calcita. La morfología de
los sedimentos y las condiciones químicas en el acuífero apuntan a dos escenarios diferentes para esta precipitación. Los
otras dos manantiales, Arch Spring en el Condado de Blair, Pennsylvania y Bushkill Spring en el Condado de Norhtampton, Pennsylvania,
no muestran evidencia de precitación de calcita. Arch Spring descarga principalmente filosilicatos mientras que Bushkill Spring
descarga fundamentalmente Sílice.
Résumé Les sources situées en contexte carbonaté karstique charrient fréquemment, outre les matières dissoutes, une charge solide.
La morphologie et la minéralogie des sédiments en suspension issus de trois sources karstiques de caractéristiques distinctes
ont été analysées : une série de particules clastiques, reflétant à la fois les secteurs des sources et les processus internes
de l’aquifère, en ressort. Les sédiments issus de Nolte Spring (Comté de Lancaster, Pennsylvanie, Etats-Unis) sont constitués
de calcite apparemment précipitée: ceci indique que l’eau atteint la sursaturation vis-à-vis de la calcite à un certain point
de l’aquifère ou de la zone non-saturée. La morphologie des sédiments et les conditions chimiques au sein de l’aquifère mènent
à deux scénarii différents pour expliquer cette précipitation. Les deux autres sources, Arch Spring (Comté de Blair, Pennsylvanie)
et Bushkill Spring (Comté de Northampton, Pennsylvanie), ne présentent aucun indice de précipitation de calcite. Arch Spring
exporte essentiellement des phyllosilicates, alors que la silice est majoritaire à Bushkill Spring.
The Salí River hydrogeological basin is one of the most productive artesian basins in Argentina. It is located in the southeastern
part of the province of Tucumán, northwestern Argentina, and its groundwater resources are developed for water supply and
irrigation. The chemical composition of the water is strongly influenced by the interaction with the basinal sediments and
by hydrologic characteristics such as the flow pattern and time of residence.
Three hydrochemical zones are defined in the study area and the processes that control the chemical composition of the water
are manifestly different in each zone. The dissolution of halite, sodium sulphate, and gypsum explains part of the contained
Na+, K+, Cl–, SO42–, and Ca2+, but other processes, such as cation exchange, calcite precipitation, weathering of aluminosilicates, and gas exchange with
the atmosphere, also contribute to the water composition.
The assessment of contamination indicators, such as pH, dissolved organic matter, dissolved oxygen, phosphate, and nitrate,
indicates that the groundwater is suitable for human consumption. However, biological contamination has been detected in samples
from some wells, especially those near the Salí River.
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The authors investigated the dead fragments of 22 species of submerged plants in the water from three limnological and trophical different water bodies (spring, river and pond). A total of 184 species of aquatic fungi, including 119 zoosporic and 65 conidial species were found on the fragments investigated plants. The most common fungus species were Aphanomyces laevis, Saprolegnia litoralis, Pythium rostratum (zoosporic fungi) and Acrodictys elaeidicola, Anguillospora longissima, Angulospora aquatica, Lemonniera aquatica, Mirandina corticola, Tetracladium marchalianum, Tetracladium maxiliformis, Trinacrium subtile (conidial fungi).
Most fungus species were observed on the specimens of Elodea canadensis (33 fungus species), Hippuris vulgaris f. submersa (33), Myriophyllum spicatum (34) and Potamogeton crispus (33), fewest on Ceratophyllum demersum (24), Fontinalis dalicarlica and Potamogeton nitens (each 25).
The most fungi were growing in the water from River Supraśl (107), the fewest in the water from Pond Dojlidy (99). Some aquatic fungus species were observed in the water of only one of the three water bodies – in Pond Dojlidy (30), in Spring Jaroszówka (32) and in the River Supraśl (39) species. Seventy-five species growing only on fragments of single submerged plants. A number of zoosporic and conidial species (22 and four, respectively) appeared new to Polish waters. Out of these 119 zoosporic species, some are known as parasites or necrotrophs of fish. 相似文献
The coastal plain bordering the southern Venice Lagoon is a reclaimed lowland characterized by high subsidence rate, and ground level and water-table depth below sea level. In this agricultural region, where the surface hydrologic network is entirely artificially controlled by irrigation/drainage canals, salinization problems have long been encountered in soils and groundwaters. Here we use isotopic and geochemical tracers to improve our understanding of the origin of salinization and mineralization of the semi-confined aquifer (0–40 m), and the freshwater inputs to this hydrological system. Water samples have been collected at different seasons in the coastal Adriatic Sea, lagoon, rivers and irrigation canals, as well as in the semi-confined aquifer at depths between 12 and 35 m (14 boreholes), and in the first confined aquifer (three boreholes drilled between 40 and 80 m depth). Stable isotopes (δ18O and δD) and conductivity profiles show that direct saline intrusion from the sea or the lagoon is observed only in a restricted coastal strip, while brackish groundwaters are found over the entire topographic and piezometric depression in the centre of the study area. Fresh groundwaters are found only in the most western zone. The sharp isotopic contrast between the western and central regions suggests disconnected hydrological circulations between these two parts of the shallow aquifer. The border between these two regions also corresponds to the limits of the most strongly subsiding zone.Our results can be interpreted in terms of a four end-member mixing scheme, involving (1) marine water from the lagoon or the open sea, (2) alpine and pre-alpine regional recharge waters carried either by the main rivers Adige, Bacchiglione and Brenta (irrigation waters) or by the regional groundwater circulation, (3) local precipitation, and (4) evaporated waters infiltrated from the surface. Infiltration from the surface is also revealed by the stratification of the electrical conductivity profiles, showing that the brackish groundwaters are overlain by a shallow layer of less saline water all over the central depression. In the first confined aquifer, the groundwaters have isotopic compositions similar to the deep groundwaters of the Venetian confined aquifers (40–400 m depth). The isotopic data and the Br/Cl ratio show that the origin of the salinization of the phreatic aquifer can be ascribed to seawater intrusion alone, with no indication of the involvement of deep brines (identified at 450 m depth) in the process.The chemical composition of the saline and brackish groundwaters is characterized by an excess of sodium and a deficit of calcium compared to conservative mixing between fresh groundwaters and seawater. This suggests that the phreatic aquifer is progressively freshening, as a consequence of the beneficial influence of the extensive irrigation/drainage network, including raised canals acting as a hydraulic barrier along the coast. This freshening tendency may have been lasting since the reclamation in the mid-twentieth century, and has probably been accelerated by the ban on groundwater abstraction since the 1970s. 相似文献