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Spatial and seasonal variations in δ 13 C AND δ 15 N of particulate organic matter in a dam‐controlled subtropical river
Author(s) -
Chen Fajin,
Jia Guodong
Publication year - 2009
Publication title -
river research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.679
H-Index - 94
eISSN - 1535-1467
pISSN - 1535-1459
DOI - 10.1002/rra.1225
Subject(s) - environmental science , particulates , hydrology (agriculture) , subtropics , plankton , monsoon , biogeochemical cycle , surface runoff , organic matter , aquatic ecosystem , δ13c , stable isotope ratio , oceanography , environmental chemistry , geology , ecology , chemistry , physics , geotechnical engineering , quantum mechanics , biology
Alteration of stream flow by artificial dams has been observed to be a significant factor for river water environmental changes. Therefore, understanding the biogeochemical processes occurring in the dam‐controlled rivers is important for water resource management. In this paper, δ 13 C and δ 15 N signatures of particulate organic matter (POM) in a dam‐controlled subtropical river, Beijiang River, in south China are reported for their spatial and seasonal distributions. POM affected by reservoirs is lighter in δ 13 C and heavier in δ 15 N relative to unaffected POM. In April, POM δ 13 C and δ 15 N values show less spatial variation in the mainstem, and suggest relatively greater contributions of terrestrial organic matter (OM) to POM. This could be related to the onset of summer monsoon that caused an abrupt increase in terrestrial input to the river by the monsoon‐induced enhancement of rainfall and runoff. In August and December, however, POM isotopic values for the sites affected by the Feilaixia dam reservoir in the middle of the river show marked changes, suggesting aquatic plankton proliferation in the reservoir during the times. Upstream from the reservoirs, POM isotopes are seasonally less varied and suggest mainly terrestrial origin. However, the isotopic signals of aquatic plankton proliferation in the reservoir in August and December is imprinted on the POM isotopic compositions downstream the reservoir, indicating far‐reaching influences of the reservoir on the downstream water environment. Copyright © 2008 John Wiley & Sons, Ltd.