• UNDERSTAND

    Water Resources

  • UNDERSTAND

    Hydrological Processes

Hydrologie

Wasser ist die kostbarste Ressource für unsere Zivilisation und jeder Mensch sollte freien Zugang zu einer sauberen, sicheren Wasserversorgung haben. Das Erreichen dieses Grundrechts ist jedoch nicht trivial, da viele der Armen in wasserbelasteten oder verschmutzten Umgebungen leben. Das Verständnis der hydrogeologischen Mechanismen von Wasserströmungen durch Wasserscheiden und Grundwassersysteme ist daher von wesentlicher Bedeutung, um den Zugang zu Wasser zu sichern, das die Bevölkerung, die Landwirtschaft, die Tierwelt und die Industrie benötigen.
Eine Stabilisotopenanalyse von Wassersystemen bietet ein einzigartiges Verständnis vieler hydrogeologischer Systeme durch die Auswertung der Sauerstoff- und Wasserstoffisotopenverhältnisse. Hierdurch erhält man tiefergehende Einblicke in Reservoir-Verweilzeiten, Grundwasserneubildungsraten und Mischmodellen. Die Stabilisotopenanalyse hilft auch, die Hydrologie von Einzugsgebieten besser zu verstehen, um die Wasserbewirtschaftung zu unterstützen und Strategien für extreme Wetterereignisse zu entwickeln und die Auswirkungen von Dürren zu reduzieren.

Analyse von Grundwasser

Grundwasser enthält viele Komponenten wie organische Stoffe oder Salze. Unter Verwendung einer Headspace-Äquilibrierungstechnik können die Sauerstoff- und Wasserstoffisotope analysiert werden, was eine Interferenz von diesen mit anderen Komponenten verhindert. Unser iso FLOW-System bietet eine hervorragende Analyseleistung für diese Art von Proben.

Frischwasserproben

Die schnellste und einfachste Analyse von Frischwasserproben erfolgt durch direkte Injektion in ein Ofensystem. Unser vario PYRO cube Elementaranalysator, ausgestattet mit dem vario LIQUID Autosampler, ermöglicht die getrennte oder sequentielle Sauerstoff- und Wasserstoffisotopenanalyse für schnellsten Probendurchsatz. Die Verwendung unserer ChromeHD-Technik bietet höchstmögliche Genauigkeit.

Gelöste Elemente

Über die Sauerstoff- und Wasserstoffisotopenmessungen hinaus kann die Analyse des gelösten organischen Kohlenstoffs, des anorganischen Kohlenstoffs und des organischen Stickstoffs einen wichtigen Einblick in die Primärproduktivität von Süßwasserökosystemen sowie die Verschmutzung durch anthropogener Stoffe liefern. Unser neuer iso TOC cube ist das einzige System, das sowohl Kohlenstoff- als auch Stickstoffisotope in Wasserproben in niedrigen Konzentrationen zuverlässig analysieren kann.

5 Treffer:

Examining nitrogen dynamics in the unsaturated zone under an inactive cesspit using chemical tracers and environmental isotopes
Applied Geochemistry (2017)
Claudia Varnier, Ricardo Hirata, Ramon Aravena

This study evaluates the dynamics of nitrogen compounds generated by infiltration of wastewater from an inactive cesspit in the unconfined and sedimentary Adamantina Aquifer in Urânia, Brazil. A monitoring station, consisting of an 11.2 m well (1.8 m in diameter) with an array of 12 tensiometers and 12 suction lysimeters, was installed to monitor the shallow unsaturated zone from 0.5 to 9 m depth. A monitoring well was also installed below the water level to monitor the shallow aquifer. High amounts of ammonium (up to 96 mg/L NH4+-N) and nitrate (up to 458 mg/L NO3−-N) were observed in the unsaturated zone porewater which is comparable to active septic systems effluents. The distribution of NO3−, Cl− and Na+, typical constituents of sewage effluents, varied seasonally and spatially, which is correlated with changes in infiltration rates between the wet and dry seasons and with hydraulic conductivity variations in interlayered sandy and clayey sediments. A detailed monitoring of porewater geochemistry demonstrated the occurrence of several important reactions affecting nitrogen dynamics in the unsaturated zone: i) oxidation of organic matter, ii) ammonification, iii) nitrification, iv) methanogenesis, v) denitrification and likely, vi) sulfate reduction. The changes in nitrogen compound distribution and δ15NNO3 and δ18ONO3 values in porewater, in association with the N2O concentration and δ15NN2O and δ18ON2O signatures in gas samples, indicate the occurrence of nitrification and denitrification, suggesting the coexistence of reducing and oxidizing microsites in the unsaturated zone. This study indicated that cesspits can generate a significant amount of nitrate even a few years after being inactivated which can represent a potential long-term source of nitrate to groundwater in highly populated areas.

Examining nitrogen dynamics in the unsaturated zone under an inactive cesspit using chemical tracers and environmental isotopes
Applied Geochemistry (2017)
Claudia Varnier, Ricardo Hirata, Ramon Aravena

This study evaluates the dynamics of nitrogen compounds generated by infiltration of wastewater from an inactive cesspit in the unconfined and sedimentary Adamantina Aquifer in Urânia, Brazil. A monitoring station, consisting of an 11.2 m well (1.8 m in diameter) with an array of 12 tensiometers and 12 suction lysimeters, was installed to monitor the shallow unsaturated zone from 0.5 to 9 m depth. A monitoring well was also installed below the water level to monitor the shallow aquifer. High amounts of ammonium (up to 96 mg/L NH4+-N) and nitrate (up to 458 mg/L NO3−-N) were observed in the unsaturated zone porewater which is comparable to active septic systems effluents. The distribution of NO3−, Cl− and Na+, typical constituents of sewage effluents, varied seasonally and spatially, which is correlated with changes in infiltration rates between the wet and dry seasons and with hydraulic conductivity variations in interlayered sandy and clayey sediments. A detailed monitoring of porewater geochemistry demonstrated the occurrence of several important reactions affecting nitrogen dynamics in the unsaturated zone: i) oxidation of organic matter, ii) ammonification, iii) nitrification, iv) methanogenesis, v) denitrification and likely, vi) sulfate reduction. The changes in nitrogen compound distribution and δ15NNO3 and δ18ONO3 values in porewater, in association with the N2O concentration and δ15NN2O and δ18ON2O signatures in gas samples, indicate the occurrence of nitrification and denitrification, suggesting the coexistence of reducing and oxidizing microsites in the unsaturated zone. This study indicated that cesspits can generate a significant amount of nitrate even a few years after being inactivated which can represent a potential long-term source of nitrate to groundwater in highly populated areas.

D/H fractionation during the sublimation of water ice
Icarus (2016)
Christophe Lécuyer, Aurélien Royer, François Fourel, Magali Seris, Laurent Simon, François Robert

Experiments of sublimation of pure water ice have been performed in the temperature range -105°C to -30°C and atmospheric partial pressures ranging from 10−6 to 10−1 mb. Sampling of both vapour and residual ice fractions has been performed with the use of a vacuum line designed for the extraction and purification of gases before the measurement of their D/H ratios. Sublimation was responsible for sizable isotopic fractionation factors in the range 0.969 to 1.123 for temperatures lying between -105°C and -30°C. The fractionation factor exhibits a cross-over at temperatures around -50°C with the water vapour fraction being D-depleted relative to the residual ice fraction at T<-50°C (αice-vapour=0.969 to 0.995). This cross-over has implications for the understanding of the atmospheric water cycle of some terrestrial planets such as the Earth or Mars. The magnitude of deuterium enrichment or depletion between ice and water vapour cannot explain the differences in the D/H ratios amongst Jupiter comets and long–period comets families nor those that have been documented between Earth's and cometary water.

D/H fractionation during the sublimation of water ice
Icarus (2016)
Christophe Lécuyer, Aurélien Royer, François Fourel, Magali Seris, Laurent Simon, François Robert

Experiments of sublimation of pure water ice have been performed in the temperature range -105°C to -30°C and atmospheric partial pressures ranging from 10−6 to 10−1 mb. Sampling of both vapour and residual ice fractions has been performed with the use of a vacuum line designed for the extraction and purification of gases before the measurement of their D/H ratios. Sublimation was responsible for sizable isotopic fractionation factors in the range 0.969 to 1.123 for temperatures lying between -105°C and -30°C. The fractionation factor exhibits a cross-over at temperatures around -50°C with the water vapour fraction being D-depleted relative to the residual ice fraction at T<-50°C (αice-vapour=0.969 to 0.995). This cross-over has implications for the understanding of the atmospheric water cycle of some terrestrial planets such as the Earth or Mars. The magnitude of deuterium enrichment or depletion between ice and water vapour cannot explain the differences in the D/H ratios amongst Jupiter comets and long–period comets families nor those that have been documented between Earth's and cometary water.

The distribution of nitrogen speciation and sources of nitrate in the north of Taihu Lake
Environmental Earth Sciences (2016)
Da Li, Xia Jiang, Kun Wang, Binghui Zheng

Meiliang Bay and Gonghu Bay, in the north of Taihu Lake, are important water sources for the city of Wuxi, and increased eutrophication now threatens the safety of drinking water. The distribution of nitrogen (N) speciation and source of N in the surface waters in the north of Taihu Lake is studied, which was an important first step in controlling N pollution. The result shows that the average concentration of ammonia (NH4+) and nitrate (NO3−) of surface water in Meiliang Bay was 0.32 and 0.35 mg/L, while 0.21 and 0.74 mg/L of Gonghu Bay, in which both bays had serious nitrate pollution. The concentrations of NH4+ and NO3− in the surface water of the two bays had a trend of gradual decrease from north to south. The maximum concentrations of NH4+ and NO3− of two bays were observed near the inflowing rivers, and the maximum concentrations of NH4+ in surface water of two bays were 0.49 and 0.61, and 0.77 and 1.38 mg/L of NO3−. The concentration of NH4+ in the interstitial water of the two bays had a trend of gradual decrease from west to east, but NO3− had the opposite tendency. The maximum concentrations of NH4+ in the interstitial water of the two bays were 5.88 and 4.64, and 3.58 and 7.18 mg/L of NO3−. The exchangeable NH4+ content in the sediment of Meiliang Bay had a trend of gradual decrease from north to south, but Gonghu Bay showed the reverse. The exchangeable NO3− content in the sediment of Meiliang Bay had a trend of gradual decrease from east to west, but a decreasing trend from north to south was observed in Gonghu Bay. The maximum concentrations of exchangeable NH4+ were determined, and the values were 96.25 and 74.90 mg/kg, as well as NO3− with the values of 12.06 and 7.08 mg/kg. Chemical fertilizer and domestic sewage were the major sources of nitrate in surface water of Gonghu Bay, contributing 39.16 and 47.79%, respectively. Domestic sewage was the major source of nitrate in Meiliang Bay, contributing 84.79%. The denitrification process in Gonghu Bay was more apparent than in Meiliang Bay. Mixing and dilution processes had important effects on changing the concentration of nitrate transportation in the two bays.
Schlagworte: N , O , po , GH , hy