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Source Water (source + water)
Selected AbstractsComparison of 85Kr and 3H Apparent Ground-Water Ages for Source Water Vulnerability in the Collyer River Catchment, Maine,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 1 2008William C. Sidle Abstract:, Apparent ground-water ages as determined by the noble gas isotope 85Kr and the water isotope 3H are compared. Refined gas extraction methodology at the wellhead permits efficient collection of Kr for 85Kr isotope enrichment. 85Kr isochrones elucidate areas of much younger ground-water ages than 3H. Declining 3H activities in the catchment prevent its correlation with the youngest measured 85Kr ages. Source water for most drinking water supplies in the Collyer River catchment is recharged within 40 years BP (2004). Mean-age (,) transport modeling suggests uncertainty of ground-water ages is greatest in the central basin area. [source] Below-ground competition between trees and grasses may overwhelm the facilitative effects of hydraulic liftECOLOGY LETTERS, Issue 8 2004F. Ludwig Abstract Under large East African Acacia trees, which were known to show hydraulic lift, we experimentally tested whether tree roots facilitate grass production or compete with grasses for below-ground resources. Prevention of tree,grass interactions through root trenching led to increased soil water content indicating that trees took up more water from the topsoil than they exuded via hydraulic lift. Biomass was higher in trenched plots compared to controls probably because of reduced competition for water. Stable isotope analyses of plant and source water showed that grasses which competed with trees used a greater proportion of deep water compared with grasses in trenched plots. Grasses therefore used hydraulically lifted water provided by trees, or took up deep soil water directly by growing deeper roots when competition with trees occurred. We conclude that any facilitative effect of hydraulic lift for neighbouring species may easily be overwhelmed by water competition in (semi-) arid regions. [source] Development of Saline Ground Water through Transpiration of Sea WaterGROUND WATER, Issue 6 2007T. Fass As vegetation usually excludes salt during water uptake, transpiration will increase the salinity of the residual water. If the source water is sea water, then the residual water may become highly saline. In the unconfined coastal aquifer of the tropical Burdekin River delta, northeastern Australia, areas of highly saline ground water with chloride concentrations up to almost three times that of sea water occur up to 15 km from the present coastline, and are attributed to transpiration by mangrove vegetation during periods of high sea level. Radiogenic (14C) carbon isotope analyses indicate that ground water with chloride concentrations between 15,000 and 35,000 mg/L is mostly between 4000 and 6000 years old, at which time sea level was 2 to 3 m higher than present. Stable isotope analyses of oxygen-18 and deuterium show no evidence for evaporative enrichment of this water. Oxygen-18, deuterium, and stable (,13C) carbon isotope analyses of ground water and soil water point to a recharge environment beneath the mangrove forests during this postglacial sea level high stand. During that period, transpiration of the mangrove forests would have led to high chloride concentrations in the residual ground water, without inducing isotopic fractionation. Due to the higher density, this hypersaline water moved downward through the aquifer by gravity and has formed lenses of highly saline ground water at the bottom of the unconfined aquifer. [source] PRODUCTION AND RELEASE OF GEOSMIN BY THE CYANOBACTERIUM OSCILLATORIA SPLENDIDA ISOLATED FROM A PHOENIX WATER SOURCEJOURNAL OF PHYCOLOGY, Issue 2001Article first published online: 24 SEP 200 Hu, Q.1, Sommerfeld, M.1 Lowry, D.1, Dempster, T.1, Westerhoff, P.2, Baker, L.3, Bruce, D. & Nguyen, M. L.2 1Department of Plant Biology and 2Department of Civil and Environmental Engineering, Arizona State University, Tempe, Arizona 85287; 3Baker Environmental Consulting, 8001 Greenwood Drive, Moundview, MN 55112 Geosmin is a common component of the off-flavors detected in the drinking water supply sources of metropolitan Phoenix (Arizona). A cyanobacterium, Oscillatoria splendida, was isolated from source water during incidents of elevated geosmin production and was implicated as a cause of earthy/musty off-flavors in the drinking water. Production of geosmin was found to be constitutive in O. splendida during all growth stages. Effects of environmental parameters on the growth characteristics, and on production and release of geosmin by O. splendida, was studied under laboratory conditions. The specific growth rate and cell-bound geosmin increased with increasing temperature from 12 to 26 °C, the range of water temperatures that occur in the drinking water supply. On a per-chlorophyll a basis, however, more geosmin was released from the cells at lower temperatures. An inverse relationship was evident between light intensity and O. splendida growth and the release of geosmin. Cell-bound geosmin, however, was higher at higher light intensities. Dark incubation initially stimulated the biosynthesis of geosmin, whereas a prolonged period of darkness (2-3 weeks) resulted in massive release of geosmin into the culture medium from lysis and cellular decomposition. Dissolved nitrogen appeared to be the limiting nutrient for O. splendida in the local water supply source. When nitrate was added to laboratory cultures, both growth and geosmin production increased. These results will be discussed in context with episodes of off-flavors in drinking waters in metropolitan Phoenix, Arizona. [source] Is heterosis in maize mediated through better water use?NEW PHYTOLOGIST, Issue 2 2010José Luis Araus Summary ,Heterosis increases yield potential and improves adaptation to stress in maize (Zea mays); however, the underlying mechanisms remain elusive. ,A set of tropical inbred lines and their hybrids were grown in the field for 2 yr under three different water regimes. First-year plant water use was evaluated by measuring instantaneous traits (stomatal conductance (gs) and steady-state chlorophyll fluorescence (Fs)) in individual leaves together with time-integrative traits, which included mineral accumulation in the whole leaves of plants and oxygen isotope enrichment above source water (,18O) and carbon isotope discrimination (,13C) in the same pooled leaves and in mature kernels. Second-year water use was evaluated by measuring leaf temperature, gs and relative water content (RWC). ,Within each growing condition, hybrids showed higher Fs, mineral accumulation, RWC, and lower leaf temperature, ,18O and ,13C than inbred lines. Therefore, hybrids had a better water status than inbred lines, regardless of the water conditions. Differences in grain yield across growing conditions were explained by differences in water-use traits, with hybrids and inbred lines following a common pattern. Within each growing condition, most variations in grain yield, between hybrids and inbred lines, were also explained by differences in plant water-use traits. ,Heterosis in tropical maize seems to be mediated by improved water use, irrespective of the water conditions during growth. [source] Grass blades as tree rings: environmentally induced changes in the oxygen isotope ratio of cellulose along the length of grass bladesNEW PHYTOLOGIST, Issue 3 2002Brent R. Helliker Summary ,,In this study, we tested the hypothesis that environmentally induced changes in the oxygen isotope ratio of leaf water are recorded in grass blade cellulose during leaf-blade expansion. ,,Grasses were grown hydroponically in chambers that allowed for control of relative humidity while keeping isotopic inputs (namely source water) constant. ,,In experiments where relative humidity was changed from 35% to 93% during grass blade expansion, a 10, shift in cellulose , 18 O was observed along single grass blades of Lolium multiflorum . However, statistically significant changes were not detectable with relative humidity of 93% to 70%. ,,It is shown that grass blades, analogously to tree rings, record environmental change on an interseasonal basis. In light of this, care must be taken to compare leaves of the same developmental stage to avoid confusion of environmental effects with physiological effects in interpretations of leaf organic material , 18 O. The results presented here confirm the ability of the current empirical models to predict the oxygen isotope ratio of cellulose in both grass blades that expanded in constant and variable growth conditions. [source] Geochemistry and source waters of rock glacier outflow, Colorado Front RangePERMAFROST AND PERIGLACIAL PROCESSES, Issue 1 2006M. W. Williams Abstract We characterize the seasonal variation in the geochemical and isotopic content of the outflow of the Green Lake 5 rock glacier (RG5), located in the Green Lakes Valley of the Colorado Front Range, USA. Between June and August, the geochemical content of rock glacier outflow does not appear to differ substantially from that of other surface waters in the Green Lakes Valley. Thus, for this alpine ecosystem at this time of year there does not appear to be large differences in water quality among rock glacier outflow, glacier and blockslope discharge, and discharge from small alpine catchments. However, in September concentrations of Mg2+ in the outflow of the rock glacier increased to more than 900,µeq,L,1 compared to values of less than 40,µeq,L,1 at all the other sites, concentrations of Ca2+ were greater than 4,000,µeq,L,1 compared to maximum values of less than 200,µeq,L,1 at all other sites, and concentrations of SO reached 7,000,µeq,L,1, compared to maximum concentrations below 120,µeq,L,1 at the other sites. Inverse geochemical modelling suggests that dissolution of pyrite, epidote, chlorite and minor calcite as well as the precipitation of silica and goethite best explain these elevated concentrations of solutes in the outflow of the rock glacier. Three component hydrograph separation using end,member mixing analysis shows that melted snow comprised an average of 30% of RG5 outflow, soil water 32%, and base flow 38%. Snow was the dominant source water in June, soil water was the dominant water source in July, and base flow was the dominant source in September. Enrichment of ,18O from ,10, in the outflow of the rock glacier compared to ,20, in snow and enrichment of deuterium excess from +,17.5, in rock glacier outflow compared to +,11, in snow, suggests that melt of internal ice that had undergone multiple melt/freeze episodes was the dominant source of base flow. Copyright © 2005 John Wiley & Sons, Ltd. [source] Sources and transport of algae and nutrients in a Californian river in a semi-arid climateFRESHWATER BIOLOGY, Issue 12 2007NOBUHITO OHTE Summary 1. To elucidate factors contributing to dissolved oxygen (DO) depletion in the Stockton Deep Water Ship Channel in the lower San Joaquin River, spatial and temporal changes in algae and nutrient concentrations were investigated in relation to flow regime under the semiarid climate conditions. 2. Chlorophyll- a (chl- a) concentration and loads indicated that most algal biomass was generated by in-stream growth in the main stem of the river. The addition of algae from tributaries and drains was small (c.15% of total chl- a load), even though high concentrations of chl- a were measured in some source waters. 3. Nitrate and soluble-reactive phosphorus (SRP) were available in excess as a nutrient source for algae. Although nitrate and SRP from upstream tributaries contributed (16.9% of total nitrate load and 10.8% of total SRP load), nutrients derived from agriculture and other sources in the middle and lower river reaches were mostly responsible (20.2% for nitrate and 48.0% for SRP) for maintaining high nitrate and SRP concentrations in the main stem. 4. A reduction in nutrient discharge would attenuate the algal blooms that accelerate DO depletion in the Stockton Deep Water Ship Channel. The N : P ratio, in the main stem suggests that SRP reduction would be a more viable option for algae reduction than nitrogen reduction. 5. Very high algal growth rates in the main stem suggest that reducing the algal seed source in upstream areas would also be an effective strategy. [source] Variability of Isotope and Major Ion Chemistry in the Allequash Basin, WisconsinGROUND WATER, Issue 7 2003John F. Walker As part of ongoing research conducted at one of the U.S. Geological Survey's Water, Energy, and Biogeochem-ical Budgets sites, work was undertaken to describe the spatial and temporal variability of stream and ground water isotopic composition and cation chemistry in the Trout Lake watershed, to relate the variability to the watershed flow system, and to identify the linkages of geochemical evolution and source of water in the watershed. The results are based on periodic sampling of sites at two scales along Allequash Creek, a small headwater stream in northern Wisconsin. Based on this sampling, there are distinct water isotopic and geochemical differences observed at a smaller hillslope scale and the larger Allequash Creek scale. The variability was larger than expected for this simple watershed, and is likely to be seen in more complex basins. Based on evidence from multiple isotopes and stream chemistry, the flow system arises from three main source waters (terrestrial-, lake-, or wetland-derived recharge) that can be identified along any flowpath using water isotopes together with geochemical characteristics such as iron concentrations. The ground water chemistry demonstrates considerable spatial variability that depends mainly on the flow-path length and water mobility through the aquifer. Calcium concentrations increase with increasing flowpath length, whereas strontium isotope ratios increase with increasing extent of stagnation in either the unsaturated or saturated zones as waters move from source to sink. The flowpath distribution we identify provides important constraints on the calibration of ground water flow models such as that undertaken by Pint et al. (this issue). [source] Stable isotopes in the source waters of the Yamuna and its tributaries: seasonal and altitudinal variations and relation to major cationsHYDROLOGICAL PROCESSES, Issue 17 2002Tarun K. Dalai Abstract Water samples from the Yamuna and its tributaries, one of the major river systems draining the Himalaya, have been analysed for their stable oxygen and hydrogen isotopes during three seasons (summer, monsoon and post-monsoon). The data show clear seasonal and altitudinal variations; waters from higher altitudes and those collected during monsoon season are characterized by relatively depleted isotopic composition. Regression analysis of ,D,,18O data of samples collected during summer and monsoon seasons shows that the slope of the best-fit lines are nearly identical to those of precipitation at New Delhi for the same period. The similarity in their slopes suggests that the isotopic composition of precipitation contributing water to these rivers are reasonably well preserved in both monsoon and non-monsoon seasons, however, during the non-monsoon period both rainfall and river waters carry signatures of evaporation. The ,deuterium excess' in river waters during the three seasons though overlap with each other, the values during October are higher. This can be understood in terms of recycled moisture contributions to precipitation. The ,altitude effect' for ,18O in these waters is determined to be 0·11, per 100 m, a factor of about two less than that reported for the Ganga source waters from similar altitudinal range. The variability in altitude effects in rivers draining the Himalaya seems to be controlled by the ,amount effect' associated with the monsoon. The significant spatial variability in altitude effect in these river basins, which are a few hundred kilometers apart, suggests that reconstruction of palaeoelevation in the Himalaya, based on ,18O-altitude gradients, would depend critically on its proper assessment in the region. This study has established a relationship between total cation abundance and ,18O in waters of the Yamuna mainstream; total cations (corrected for cyclic components) double for a 1·4 km decrease in altitude as the Yamuna flows downstream. Copyright © 2002 John Wiley & Sons, Ltd. [source] Geochemistry and source waters of rock glacier outflow, Colorado Front RangePERMAFROST AND PERIGLACIAL PROCESSES, Issue 1 2006M. W. Williams Abstract We characterize the seasonal variation in the geochemical and isotopic content of the outflow of the Green Lake 5 rock glacier (RG5), located in the Green Lakes Valley of the Colorado Front Range, USA. Between June and August, the geochemical content of rock glacier outflow does not appear to differ substantially from that of other surface waters in the Green Lakes Valley. Thus, for this alpine ecosystem at this time of year there does not appear to be large differences in water quality among rock glacier outflow, glacier and blockslope discharge, and discharge from small alpine catchments. However, in September concentrations of Mg2+ in the outflow of the rock glacier increased to more than 900,µeq,L,1 compared to values of less than 40,µeq,L,1 at all the other sites, concentrations of Ca2+ were greater than 4,000,µeq,L,1 compared to maximum values of less than 200,µeq,L,1 at all other sites, and concentrations of SO reached 7,000,µeq,L,1, compared to maximum concentrations below 120,µeq,L,1 at the other sites. Inverse geochemical modelling suggests that dissolution of pyrite, epidote, chlorite and minor calcite as well as the precipitation of silica and goethite best explain these elevated concentrations of solutes in the outflow of the rock glacier. Three component hydrograph separation using end,member mixing analysis shows that melted snow comprised an average of 30% of RG5 outflow, soil water 32%, and base flow 38%. Snow was the dominant source water in June, soil water was the dominant water source in July, and base flow was the dominant source in September. Enrichment of ,18O from ,10, in the outflow of the rock glacier compared to ,20, in snow and enrichment of deuterium excess from +,17.5, in rock glacier outflow compared to +,11, in snow, suggests that melt of internal ice that had undergone multiple melt/freeze episodes was the dominant source of base flow. Copyright © 2005 John Wiley & Sons, Ltd. [source] | |||||||||||||