TY - JOUR
T1 - Dripwater organic matter and trace element geochemistry in a semi-arid karst environment
T2 - Implications for speleothem paleoclimatology
AU - Rutlidge, Helen
AU - Baker, Andy
AU - Marjo, Christopher E.
AU - Andersen, Martin S.
AU - Graham, Peter W.
AU - Cuthbert, Mark O.
AU - Rau, Gabriel C.
AU - Roshan, Hamid
AU - Markowska, Monika
AU - Mariethoz, Gregoire
AU - Jex, Catherine N.
PY - 2014/6/15
Y1 - 2014/6/15
N2 - A series of four short-term infiltration experiments which revealed hydrochemical responses relevant to semi-arid karst environments were carried out above Cathedral Cave, Wellington, New South Wales (NSW), Australia. Dripwater samples were collected at two sites for trace element and organic matter analysis. Organic matter was characterised using fluorescence and interpreted using a PARAFAC model. Three components were isolated that represented unprocessed, soil-derived humic-like and fulvic-like material, processed humic/fulvic-like material and tryptophan-like fluorescence. Principal Component Analysis (PCA) performed on the entire dataset comprising trace element concentrations and PARAFAC scores revealed two dominant components that were identified as soil and limestone bedrock. The soil component was assigned based on significant contributions from the PARAFAC scores and additionally included Ba, Cu, Ni and Mg. The bedrock component included the expected elements of Ca, Mg and Sr as well as Si. The same elemental behaviour was observed in recent stalagmite growth collected from the site. Our experiments demonstrate that existing paleoclimate interpretations of speleothem Mg and Sr, developed in regions of positive water balance, are not readily applicable to water limited environments. We provide a new interpretation of trace element signatures unique to speleothems from water limited karst environments.
AB - A series of four short-term infiltration experiments which revealed hydrochemical responses relevant to semi-arid karst environments were carried out above Cathedral Cave, Wellington, New South Wales (NSW), Australia. Dripwater samples were collected at two sites for trace element and organic matter analysis. Organic matter was characterised using fluorescence and interpreted using a PARAFAC model. Three components were isolated that represented unprocessed, soil-derived humic-like and fulvic-like material, processed humic/fulvic-like material and tryptophan-like fluorescence. Principal Component Analysis (PCA) performed on the entire dataset comprising trace element concentrations and PARAFAC scores revealed two dominant components that were identified as soil and limestone bedrock. The soil component was assigned based on significant contributions from the PARAFAC scores and additionally included Ba, Cu, Ni and Mg. The bedrock component included the expected elements of Ca, Mg and Sr as well as Si. The same elemental behaviour was observed in recent stalagmite growth collected from the site. Our experiments demonstrate that existing paleoclimate interpretations of speleothem Mg and Sr, developed in regions of positive water balance, are not readily applicable to water limited environments. We provide a new interpretation of trace element signatures unique to speleothems from water limited karst environments.
UR - http://www.scopus.com/inward/record.url?scp=84898420155&partnerID=8YFLogxK
U2 - 10.1016/j.gca.2014.03.036
DO - 10.1016/j.gca.2014.03.036
M3 - Article
AN - SCOPUS:84898420155
SN - 0016-7037
VL - 135
SP - 217
EP - 230
JO - Geochimica et Cosmochimica Acta
JF - Geochimica et Cosmochimica Acta
ER -