Studies of ³²Si in Different Aquifers and Implications for Groundwater Dating

The Missing Silica Sink: Revisiting the Marine Sedimentary Si Cycle Using Cosmogenic 32Si

“…This estimate of 32 Si particulate flux from a drainage region is a likely maximum value as a portion of the 32 Si that is deposited on land remains in groundwater, is taken up by plants and recycled in terrestrial biomass, or is retained in deeper subsurface soil minerals. In a study of the use of 32 Si for dating groundwater, its activity in soils was investigated (Franke et al, ; Fröhlich et al, ), and 32 Si was preferentially found in horizons containing humics, iron and manganese oxyhydroxides, and clays. In an ~4 m soil profile, the depth‐integrated soil inventory was 0.4 Bq/m 2 , which was 67% of the 0.6 Bq/m 2 total 32 Si inventory supplied to that region from the atmosphere (Franke et al, ; Fröhlich et al, ).…”

“…In a study of the use of 32 Si for dating groundwater, its activity in soils was investigated (Franke et al, ; Fröhlich et al, ), and 32 Si was preferentially found in horizons containing humics, iron and manganese oxyhydroxides, and clays. In an ~4 m soil profile, the depth‐integrated soil inventory was 0.4 Bq/m 2 , which was 67% of the 0.6 Bq/m 2 total 32 Si inventory supplied to that region from the atmosphere (Franke et al, ; Fröhlich et al, ). The rest of the 32 Si presumably remained dissolved in groundwater, precipitated and recycled as phytoliths in plants, or was incorporated into weathering products deeper in the regolith and unlikely to be eroded (more detailed discussion in the supporting information) (Alexandre et al, ; Carnelli et al, ; Cornelis et al, ; Epstein, ; Hou et al, ; Kondo & Iwasa, ; Ma & Yamaji, ; Mandal, ; Mitani & Ma, ; Vincent et al, ).…”

“…It has been used to determine particle mixing rates in the deep sea (DeMaster & Cochran, 1982), sedimentation rates in deltas and lakes (Nijampurkar et al, 1998;Morgenstern et al, 2001Morgenstern et al, , 2013Suckow et al, 2001), and ages of glacier ice (Nijampurkar et al, 1982(Nijampurkar et al, , 1985Morgenstern et al, 1996Morgenstern et al, , 2000. It has also been used as a tracer of stable silicon inputs into various water masses (Nijampurkar et al, 1966(Nijampurkar et al, , 1983Lal et al, 1970Lal et al, , 1976DeMaster, 1980;Morgenstern et al, 1995) and to date groundwater ages in aquifers (Nijampurkar et al, 1966;Lal et al, 1970;Franke et al, 1988;Fröhlich et al, 1988;Morgenstern et al, 1995). Artificially produced 32 Si (via spallation of Vanadium) was first used to study biogenic silica production rates in the Weddell-Scotia Seas by Tréguer et al (1991).…”

32Si Dating of Marine Sediments from Bangladesh

“…Since its discovery by , the potential of 32 Si to help understand environmental processes such as glacier dynamics, ocean and atmospheric circulation, sedimentation in lakes and oceans, and groundwater flow has been investigated by several researchers and research groups (e.g. Dansgaard et al 1966;Nijampurkar et al 1966;Kharkar et al 1969;Lal et al 1970Lal et al , 1976Krishnaswami et al 1971;Clausen 1973;DeMaster and Cochran 1982;Fröhlich et. al.…”