�ber den Deuterium-Gehalt von Niederschlags- und Grundwasser

Illuminating hydrological processes at the soil‐vegetation‐atmosphere interface with water stable isotopes

“…Why groundwater or streamwater does not show an evaporation fractionation signal has been studied for decades. Possible explanations include that the evaporation fractionation signal in the topsoil is equalized by the preferential recharge of in heavy isotopes depleted water during the vegetation dormancy [e.g., Brinkmann et al ., ] or that the groundwater recharge is limited to high‐intensity rainfall events or snow melt bypassing the topsoil through preferential flow paths without altering its isotopic composition by evaporation [e.g., Komor and Emerson , ; Mathieu and Bariac , ; Schlaepfer et al ., ]. The other way around, Gat and Airey [] suggested that an evaporation fractionation signal could only be introduced into the groundwater when the antecedent soil water of negative lc‐excess is flushed with newly introduced rainwater.…”

“…The first studies that realized the potential of water isotopes in soils to detect subsurface processes focused on the radioactive tritium ( 3 H) concentration after the peak of the nuclear bomb test in the 1950s and 1960s [ Münnich , ] or in tracer experiments with tritiated (artificially 3 H enriched) water [ Zimmermann et al ., ; Blume et al ., ; Kline and Jordan , ]. However, the potential of the natural seasonal variation of the stable isotopes in the rainfall water was also acknowledged during that time [ Brinkmann et al ., ]. Since then, the isotopic composition of the soil waters has been used in various studies dealing with a wide range of processes that occur in the critical zone between the groundwater and the atmosphere.…”

Global Isotope Hydrogeology―Review

“…Some scenarios that may lead to the condition: groundwater δ 18 O < amount‐weighted annual precipitation δ 18 O. These include (a) groundwater aquifers replenished in part by precipitation that fell at higher elevations than the land surface at the location that the sample was collected (e.g., Gonfiantini et al, ; Payne & Yurtsever, ); (b) recharge of surface waters diverted for agricultural, domestic or industrial uses (e.g., Williams & Rodoni, ); (c) disproportionate recharge from intensive rainfall, in places where precipitation rates and δ 18 O values correlate inversely (e.g., Geirnaert et al, ; Vogel & Van Urk, ); (d) higher recharge/precipitation ratios for cold‐season precipitation relative to warm‐season precipitation (e.g., Brinkmann et al, ; Simpson et al, ); (e) retention of groundwater derived from precipitation during the late‐Pleistocene, when global atmospheric temperatures were as much as ~4°C cooler‐than present (e.g., Gonfiantini et al, ; Phillips et al, ; Vogel & Ehhalt, ); and (f) transport of waters from a place where precipitation δ 18 O values are relatively low to another place where precipitation δ 18 O values are relatively high before the water recharges (e.g., Liu & Yamanaka, ). These processes are not mutually exclusive; more than one may affect groundwater isotope compositions (e.g., Liu & Yamanaka, ).…”

Composição isotópica da água de chuva e da água do solo em floresta amazônica do tipo terra firme, região de Manaus

“…Por se tratar de um solo de textura fina essas observa96es sao ainda mais acentuadas, conforme ja observado por Brinkmann et al (1963). 0 periodo estudado nao inclui parte da e3-ta<;ao mais chuvosa, quando os valores isot6-picos sao mais negativos e que, certamente, levariam as medias ponderadas de 0 2 H e 0 18 0, a val ores mais negativos.…”