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Typhoon‐Enhanced Silicon and Nitrogen Exports in a Mountainous Catchment
Author(s) -
Su Ni,
Yang Shouye,
Xie Xiaolei
Publication year - 2018
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1029/2018jg004389
Subject(s) - weathering , carbonate , silicate , environmental chemistry , environmental science , bedrock , precipitation , geochemistry , geology , hydrology (agriculture) , chemistry , geomorphology , physics , geotechnical engineering , organic chemistry , meteorology
Tropical storms play a profound role in driving global terrestrial material from continents to oceans. We investigated the continuous changes in the major ion chemistry, hydrogen and oxygen stable isotopes of water (δD and δ 18 O), nitrogen and oxygen stable isotopes of nitrate (δ 15 N‐NO 3 − and δ 18 O‐NO 3 − ), and radiogenic strontium isotopes ( 87 Sr/ 86 Sr) for the Mulanxi River catchment in southeast China when a strong typhoon made landfall on the coasts to acquire a rapid increase in river discharge (~50 times). High rates of carbonate weathering and thus CO 2 consumption during an intense precipitation event suggested the increased active weathering of carbonate minerals, while the release of silicate solute‐rich soil waters during the storm could induce a greater relative contribution of surface weathering to the solute load, rather than active weathering of silicate bedrock. The related total dissolved Si flux of 940 t accounted for ~5.8% of the whole year, particularly revealing a flux contribution of the Si‐rich soil waters for 37% at least. Additionally, we observed a significant increase in δ 18 O‐NO 3 − and a slight decrease in δ 15 N‐NO 3 − after the storm, whereas the concentrations of major elements overall recovered to pretyphoon levels. We infer that the posttyphoon change in the nitrate isotopic composition is caused by the coupled effects of nitrification and denitrification processes at the sediment‐water interface, which thus modify isotopic compositions. This work expands our understanding of extreme climate events that may play in element sources and cycling processes in rivers.