Sj. Kao et Kk. Liu, PARTICULATE ORGANIC-CARBON EXPORT FROM A SUBTROPICAL MOUNTAINOUS RIVER (LANYANG HSI) IN TAIWAN, Limnology and oceanography, 41(8), 1996, pp. 1749-1757
Small mountainous rivers have received increasing attention in recent
years because of their high yield of sediments and particulate organic
matter. A one-year (1993-1994) study of the fluxes of the total suspe
nded matter (TSM) and particulate organic carbon (POC) in different pa
rts of Lanyang Hsi, a typical small mountainous river in subtropical n
ortheastern Taiwan indicated that the mean TSM and POC yields of the w
hole drainage area were high (3,600 and 23 g m(-2) yr(-1), respectivel
y) but that the yields of less disturbed (control) tributaries were on
ly 1/30, of the mean yields of the whole area. Radiocarbon analysis by
accelerator mass spectrometry gave very old apparent ages (>10,000 yr
) to the POC in the main channel, indicating that >70% of the POC prod
uced in the drainage basin was probably derived from kerogen in the be
drock. TSM yields for 1970-1991, calculated from historical records of
runoffs and TSM concentrations, showed large fluctuations from year t
o year; however, the average yield after 1976 (8,335 g m(-2) yr(-1)) w
as higher than that before 1976 (3,127 g m(-2) yr(-1)) by a factor of
2.7, suggesting a significant increase in sediment production related
to massive road construction in 1975-1980. The average POC yield for 1
977-1994 was calculated to be 53 g m(-2) yr(-1). The very high yields
of TSM and POC in recent years are attributable to human disturbances.