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87 Sr/ 86 Sr as a tracer of groundwater discharge and precipitation recharge in the Glacial Lake Agassiz Peatlands, northern Minnesota
Author(s) -
Hogan James F.,
Blum Joel D.,
Siegel Donald I.,
Glaser Paul H.
Publication year - 2000
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2000wr900233
Subject(s) - peat , bog , groundwater recharge , groundwater , hydrology (agriculture) , geology , bedrock , water table , groundwater discharge , glacial period , precipitation , aquifer , geomorphology , ecology , geography , geotechnical engineering , meteorology , biology
A contrast in the 87 Sr/ 86 Sr ratio of atmospherically derived Sr (∼0.710) and Sr from regional bedrock (>0.730) allows quantification of the proportions of precipitation recharge and groundwater discharge into peat columns of bogs and fens in the Glacial Lake Agassiz Peatlands. Two contrasting bog‐fen pairs were studied: the Lost River peatland located over a regional groundwater discharge zone and the Red Lake peatland situated atop a hydrologic divide where recharge is expected to occur. Bog pore waters consist of 90–100% precipitation in the upper 2 m, below which they mix with groundwater. Adjacent fens consist mostly of groundwater, ranging from ∼30% near the surface to ∼100% with depth. At the Red Lake peatland, mixing relations suggest an additional Sr source that may be peat mineralization. Distinct 87 Sr/ 86 Sr and [Ca]/[Sr] ratios for groundwater discharging into bog and fen sites are indicative of distinct groundwater sources and are likely indicative of flow paths at two different length scales.