Premium
Stable carbon and nitrogen isotope systematics in a human‐disturbed watershed (Lanyang‐Hsi) in Taiwan and the estimation of biogenic particulate organic carbon and nitrogen fluxes
Author(s) -
Kao S. J.,
Liu K. K.
Publication year - 2000
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/1999gb900079
Subject(s) - particulates , tributary , isotopes of nitrogen , environmental chemistry , nitrogen , stable isotope ratio , soil water , flux (metallurgy) , carbon fibers , detritus , isotopes of carbon , environmental science , total organic carbon , chemistry , hydrology (agriculture) , geology , ecology , soil science , biology , physics , cartography , materials science , organic chemistry , geotechnical engineering , quantum mechanics , composite number , composite material , geography
Systematic investigation of carbon and nitrogen isotopic compositions of suspended particulate matters, plants, soils, sediments, and bed rocks was conducted during 1993–1994 in the Lanyang‐Hsi watershed, which is a typical small Oceania river. The dramatic increase in particle concentration and changes in nitrogen isotopic composition from tributaries to main stem indicate a shift in the major sources of particulate matter from soil and plant detritus (biogenic) for tributaries to poorly weathered rock fragments (lithogenic) and soil for the main stem. Using a two end‐member mixing of nitrogen isotopes and the load‐runoff relationship, we estimated the mean yield of biogenic particulate nitrogen (PN) in this watershed to be 0.41 ± 0.19 g N m −2 yr −1 , which comprised only 9% of the total PN yield. Assuming the mean atomic C/N ratio (13.6) of soil samples as that for the biogenic end‐member, we estimated the yield of biogenic particulate organic carbon (POC) to be 4.9 ± 2.2 g C m −2 yr −1 . If this represents the natural POC yield in Oceania islands, more than half of the POC flux from these islands could have been humanly induced. The flux‐weighted mean δ 15 N and δ 13 C values of exported particles were +3.6‰ and −25.3‰. The δ 13 C value is similar to those observed elsewhere, whereas the δ 15 value is considerably heavier, apparently attributable to the high contribution of lithogenic PN induced by human disturbance.