Long-term water use of a plantation of river red gum (Eucalyptus camaldulensis) was estimated using a groundwater hydrographic separation technique and compared with transpiration rate estimated by ...sap flow measurements using the heat pulse method. The recession components of hydrographs of wells inside and outside the plantation were compared for a period of 24 months. During summer the difference in gradient between the two well locations was assumed to equal the water use by the plantation. With this assumption, the hydrograph separation technique allowed differences between rates of transpiration to be estimated. Water use was found to range from 0.9 to 1.3 mm day(-1) in summer, based on analysis of the recession curve, and 0.95 mm day(-1) in winter, based on the accession curve. Stand transpiration, estimated by the heat pulse method, was found to be 0.96 mm day(-1). In native woodland where water levels are deeper (up to 16 m) the ascending components of the hydrographs of wells inside and outside the woodland were used to estimate the water use of the woodland. This was found also to be 0.9 mm day(-1).
Seaweed, vitamin K, and warfarin Bartle, W R; Madorin, P; Ferland, G
American journal of health-system pharmacy,
2001-Dec-01, Letnik:
58, Številka:
23
Journal Article
The chemical characteristics of surface water, base flow and groundwater in a first-order catchment in the wheatbelt of Western Australia were used to study the weathering process and its ...relationship to the development of groundwater and stream salinity. Meteoric water infiltrates through the unsaturated zone to the water table aquifer and through the aquifer outcrop in the case of a confined aquifer. The groundwater composition changes in space and time, becoming more saline with depth and distance away from the recharge zone. The concentration of salt in the system can be explained by four main mechanisms: withdrawal of water through uptake by plant roots for transpiration; loss of water during the weathering process and the formation of new minerals; leakage between aquifers; evaporation upstream of geological structures and near discharge zones. The groundwater is mainly of Na-Cl type, and is at saturation with respect to most of the carbonate minerals, chalcedony, talc and tremolite. The water changes in its chemical composition as rock-water interaction takes place. The weathering products are gibbsite and kaolinite, with the release of Na+ K+, Mg2+, Ca2+, HCO-3 and H4SiO4. The preclearing weathering products are produced in a system open to CO2 (through the plant roots), with groundwater under this system having excess Na+. After clearing the system becomes depleted in CO2 and the groundwater becomes depleted in Na+ through exchange with Mg2+ from the rock surface. Geochemical modelling showed that most of the constituents in groundwater can be accounted for by taking into consideration the constituents of rainfall, with minor additions from the weathering process.
A major problem in managing and reclaiming saline land is identifying areas of recharge and discharge in a catchment. In a first-order catchment in the wheatbelt of Western Australia, four trends of ...water level changes have been observed: monotonically rising water levels; continuously rising water levels with seasonal fluctuations; continuously falling water levels; seasonally fluctuating water levels. Each pattern is associated with a specific hydrologic mechanism--recharge, recharge-discharge and discharge. The spatial distribution of the aquifer systems in the catchment follows a configuration which is controlled by the basin morphology. Recharge takes place in confined aquifers at the watershed and in the uplands; recharge-discharge occurs in the unconfined to semiconfined aquifer of the midslopes, and discharge becomes dominant along the unconfined aquifers of the drainage lines. The main areas of discharge of higher-salinity groundwater occur just upstream of geological structures along the drainage line. Surface water dams were found to contribute to the establishment of new discharge areas. They cause increased pressure in the deep aquifers, resulting in a rise in water levels and groundwater discharge below the dams.
A study of water and salt balances within a first-order catchment in the Western Australian wheatbelt has shown that the salt load in the main surface drainage comes largely from groundwater ...discharging upstream from the basement highs and dykes that extend across the surface drainage and conductive channels within the regolith. Although salt fall from rainfall is about 2.0 g m-2 year-1 (Cl-), the stream load ranges from 180 to 850 g m-2 year-1 with an out/input ratio of 100-425. Salt storage in the catchment Salt storage in the catchment varies from 900-4000 g m-2 in the top 3 m, to 27000-71000 g m-2 in the 3-15 m depth range and 5000-21 000 g m-2 below 15 m. Groundwater discharge calculated using Br and Cl as tracers for the groundwater component fluctuates between 20 and 40% of streamflow. Stream salinity during the last 3 years was below the long-term average. This is attributed to a reduction in groundwater discharge caused by low rainfall during this period. The downward displacement and leaching of salt stored in the regolith indicates that if groundwater levels continue to rise, the quantity and salinity of groundwater discharge will continue to increase causing further rises in stream salinity.
Molecular mass distributions of coal‐tar pitch fractions separated by planar chromatography (P‐C) have been compared by matrix‐assisted laser desorption/ionization (MALDI) mass spectrometry, carried ...out in the absence of added matrix. Solvent pairs used in the P‐C separation were pyridine–acetonitrile, pyridine–N,N‐dimethylformamide and tetrahydrofuran–toluene. Molecular complexity and average molecular masses were found to increase with decreasing mobilities of the fractions. UV‐fluorescence spectroscopy showed shifts of peak intensities to longer wavelengths and decreasing quantum yields, suggesting the presence of progressively greater concentrations of large polynuclear aromatic systems with decreasing mobility of samples in P‐C. Fractions immobile in pyridine gave MALDI mass spectra of low intensity, indicating that larger molecules are less easily desorbed or ionized. The observed similarity of upper‐mass limits of planar‐chromatographic fractions of different mobility is thought to suggest the presence of relatively large‐molecular mass (MM) materials of variable polarity in coal‐tar pitch. The results were consistent with earlier investigations showing the presence of high molecular mass materials in coal‐derived liquids. MM‐distributions determined by size exclusion chromatography (SEC) were also observed to increase with decreasing mobility of the fractions on P‐C plates. This qualitative agreement with results from MALDI‐MS indicates that reported shifts of polar molecules to shorter elution times in SEC (i.e. to apparently larger‐MMs) were not of a sufficient magnitude to distort the relative ordering of MM‐distributions of PC‐fractions observed by SEC. A number of problems relating to the refinement of MALDI‐MS determinations on complex mixtures are discussed.
