Physical-chemical characterization of uranium containing sediments

The presented paper is intended to study the chemical behaviour of combined geogenicanthropogenic uranium content in specific stream sediments. The sampling points have been chosen with respect to the natural conditions in the locality of groundwater outflow from a former uranium mine adit in Považský Inovec mountain range, near Kálnica village. Besides the total uranium determination and physical-chemical characterization of the relevant water- and sediment samples we carried out modified Tessier type sequential fractionation extractions of natural- and artificially contaminated sediment samples after time dependent agitation in air and in the atmosphere of argon. The obtained results have been compared with those fulfilled with montmorillonite K-10. The total uranium concentrations of the relevant groundwater samples as well as of stream sediments have been determined by ICP-MS using HP 4500. The determinations of uranium in extracts have been accomplished according STN757614, utilizing arsenazo III as a selective complex forming reagent for spectrophotometric determination of uranyl-ions at 650 nm. The total uranium concentration of the groundwater outflow and in the sediment taken in its immediate vicinity has been 31.75±0.35 μg dm-3 and 38.0±2.7 μg g-1 respectively. Unlike montmorillonit K-10, in which the carbonate-bound fraction of uranium after 1 week aeration and agitation in argon atmosphere represents 22.8% and 18.6% respectively, uranium in investigated sediments has been present predominantly in carbonate-bound fraction-reaching under similar conditions 38.6% and 26.6%, respectively.

ANALISIS KURVA RESESI ALIRAN DASAR MENGGUNAKAN MODEL RESERVOIR LINIER RECESSION CURVE HYDROOFFICE PADA DAS WURYANTORO KABUPATEN WONOGIRI PROPINSI JAWA TENGAH

The hydrograph recession curve expresses the theoretical relationship between the aquifer structure and the flow of groundwater flowing into the river basin channel. These theoretical relationships are often empirically depicted using the base flow recession curve. The hydrograph recession curve is commonly used to estimate the recessionary parameters, aquifer properties and to evaluate alternative hydrological hypotheses. The river basin hydrograph recession curve records the behavior of the relationship between the aquifer structure and its association with groundwater outflow to the river channel. This research was conducted with the aim: to analyze the characteristics of the baseflow recession based on the parameters and coefficients of the recession, and the shape of the individual recession curve and the master recession curve. The characteristics of the baseflow recession to research sub-watershed have the recession curves tend to sloped, describing the water storage well enough. The parameter Q0 (recession early), α and the recession constant Krb ranging from 0,80 – 0,90 for the individual and master recession curve in all three research sub-watershed. This calculation result indicates that the recession characteristics in three research sub-watershed have the condition of water storage is excellent, because they are supported by the aquifer characteristics dominated by the geological structures are more permeable (porous).

Minimum dissipation of potential energy by groundwater outflow results in a simple linear catchment reservoir

Streamflow recessions of catchments during periods of no recharge can often be reproduced by a simple, linear reservoir despite the complexity of the catchments. Here we show that such a simple linear behaviour can result from the assumption that groundwater drains from smaller units within the catchment into the stream in such a way that the potential energy of groundwater of the whole catchment is dissipated at the minimum possible rate. To do so, we consider the mass balances of groundwater of two connected sub-catchments that form a hypothetical catchment and consider the depletion of potential energy as groundwater drains into the channel network. We show analytically that the catchment-level depletion of groundwater potential energy has a minimum with respect to a groundwater flux that connects the sub-catchments. The catchment-level minimisation results in equal groundwater levels in the sub-catchments with respect to their channels, which then results in a simple, linear reservoir model for the whole catchment. We then discuss the requirements for such a minimum dissipation state to exist and propose possible mechanisms by which groundwater flow can organise and evolve to such a state. We conclude that the simple, linear response in streamflow recession can be interpreted as the outcome of groundwater flow within the catchment organised to dissipate potential energy at the minimum possible rate. Hence, it would seem that energetic considerations provide an important, additional constraint in the dynamics of water flow networks within catchments that potentially reduces the problem of equifinality in hydrology.

Multi-level qualification of Parafluvial Exchange within the Hyporheic Zone Affected by River Sinuosity and Seasonal Change using Multi-tracer Methods

Exchange of water in the parafluvial zone, located along the boundaries of meandering streams, arises in response to seasonal variation and spatial distribution. Remarkably, few studies have applied multi-tracer methods for qualitative scrutiny of losing (recharge) or gaining (discharge) reaches along the parafluvial zone. Hence, the main objective of this study is to qualitatively characterize the spatio-temporal alteration in parafluvial exchange within the hyporheic zone (PEHZ) by simultaneous application of multi-tracer methods. For this approach, first, Hierarchical Cluster Analysis (HCA) in conjunction with groundwater hydrochemistry analysis was used to evaluate the representativeness of parafluvial assessment network. Then, water stable isotope compositions (δ18O and δ2H), radioisotope (222Rn), and environmental tracers (Temperature and EC) were measured at multiple depths (20 cm to 100 cm depths below streambed) during the wet and dry season to qualitatively elucidate the PEHZ in the Ghezel-Ozan River, a third order river located in the northwest of Iran. By groundwater hydrochemistry assessment identified, NaHCO3 and CaHCO3 as the dominant water type in dry and wet season, respectively. Moreover, the HCA approach designed two different clusters for each season for accurate interpretation of PEHZ. Results obtained from stable isotope and environmental tracer analysis of bore water, surface water, and parafluvial water distinguished stream-aquifer connectivity with highly seasonal and spatial variations. In the dry season, for example, δ18O, δ2H, and EC varied from −3.59 to −1.88 (‰ VSMOW), −31.08 to −24.06 (‰ VSMOW), and 234 to 740.65 μS/cm respectively. Also, the results acquired from the integration of δ18O and EC revealed complex spatio-temporal stream-aquifer connectivity (PEHZ). In low flow conditions, groundwater outflow mainly occurred at 100 cm depth while the dominance of groundwater outflow at 20 cm depth prevailed during high flow conditions. The continuous and point scale measurements of temperature and 222Rn were highly in accordance with the results of δ18O and EC. Furthermore, diel temperature fluctuation, as well as radon activity variations at multi-level scale, expressed the PEHZ (especially at depth greater than 60 cm) are affected by large-scale regional flow-field which is embedded within. The synthesized approaches used in this study provide a useful insight into the spatiotemporal changes of stream-aquifer connectivity which make the more efficient monitoring and interpretation of hydrological processes possible. They can be, furthermore, utilized to pinpoint the losing/gaining reaches accurately to tackle environmental problems such as monitoring the transport of anthropogenic contaminants in a system.

KAJIAN KEBERLANJUTAN ALIRAN DASAR SUNGAI MELALUI ANALISIS KURVA RESESI HIDROGRAF PADA DAS KEDUANG KABUPATEN WONOGIRI PROVINSI JAWA TENGAH

The streamflow hydrograph recession curve notes that behavior of the relationship between the aquifer structure and dependencies with the groundwater outflow towards river basin channel. The recession behavior of river basin hydrographs will investigate to understand the hydrology processes of the river basin in the future. This research was conducted with the aim: to analyze the characteristics of the baseflow recession based on the parameters and coefficients of the recession, and the shape of the individual recession curve and the master recession curves both manually and through the processing of genetic algorithms using a linear reservoir model of hydrooffice software package recession curve (RC) 4.0. The results of the visualization of the recession curve shape of the watershed of the research shows there is a very interesting trend in the watershed storage process.The characteristics of the baseflow recession to research watershed with the recession curve slope describe the baseflow recession conditions, especially excellent water storage. The river basin of Keduang have the form of a relatively sloping recession curves, both individual and master recession curve with relatively high recession constant ranged between 0,80 – 0,90 have baseflow recession characteristic is excellent, i.e. the watershed water storage which is the higher volume of water storage.

CO2 Emission to the Atmosphere from Carbonate Waters: The Study Case of the Lublin Upland and Roztocze Regions

The concentration of carbon dioxide dissolved in water (CO2(aq)) was measured in consecutive phases of the hydrological cycle. Its potentially possible degassing from groundwaters to the atmosphere was also assessed. The research was conducted in the area of occurrence of carbonate rocks of the Lublin Upland and Roztocze (SE Poland). The results of the measurements of CO2(aq) concentration varied as follows (min-max/mean): precipitation waters < 1-3/2.6 mg · dm−3, soil waters 3-50/14.2 mg · dm−3, groundwaters 10-70/30.3 mg · dm−3, river waters < 1-21/7.6 mg · dm−3. The measure of degassing of carbon dioxide from groundwaters to the atmosphere was a decrease in CO2(aq) concentration in fluvial outflow. Based on the value of groundwater outflow from the Lublin Upland and Roztocze, the annual carbon dioxide emission from waters to the atmosphere was calculated at a level of 50 thousand Mg · year−1. This value constitutes approximately 1% of anthropogenic emission of carbon dioxide originating from environmentally harmful industrial plants in the Lublin province.

Recharge contribution to the Guarani Aquifer System estimated from the water balance method in a representative watershed

The contribution of recharge to regional groundwater flow systems is essential information required to establish sustainable water resources management. The objective of this work was to determine the groundwater outflow in the Ribeirão da Onça Basin using a water balance model of the saturated soil zone. The basin is located in the outcrop region of the Guarani Aquifer System (GAS). The water balance method involved the determination of direct recharge values, groundwater storage variation and base flow. The direct recharge was determined by the water table fluctuation method (WTF). The base flow was calculated by the hydrograph separation method, which was generated by a rain-flow model supported by biweekly streamflow measurements in the control section. Undisturbed soil samples were collected at depths corresponding to the variation zone of the groundwater level to determine the specific yield of the soil (drainable porosity). Water balances were performed in the saturated zone for the hydrological years from February 2004 to January 2007. The direct recharge ranged from 14.0% to 38.0%, and groundwater outflow from 0.4% to 2.4% of the respective rainfall during the same period.