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Organic matter losses from four watersheds in the humid tropics 1
Author(s) -
Brinson Mark M.
Publication year - 1976
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1976.21.4.0572
Subject(s) - surface runoff , hydrology (agriculture) , environmental science , watershed , organic matter , dry season , flushing , particulates , particulate organic matter , wet season , zoology , ecology , geology , biology , geotechnical engineering , machine learning , endocrinology , computer science
Organic matter (OM) losses in runoff water were examined for four watersheds in Guatemala, ranging in size between 170 and 5,247 km 2 . Total organic matter (TOM) concentrations for the largest river were highest (14.8–19.3 mg liter ‒1 ) at the beginning of the wet season, due to an abrupt increase in particulate fractions. This initial flushing effect was followed by lower concentrations which had decreased to near dry season values (3.90–5.35 mg TOM liter ‒1 ) 4 months later. Export of TOM was estimated to be between 5.4 and 12 g m ‒ 2 yr ‒1 for three of the four watersheds. The fourth, dominated by swamp forest, showed a higher maximum concentration (43.7 mg TOM liter ‒1 ) and greater export, the latter partially attributable to flushing by floodwaters that overflowed an adjacent watershed. These data and those from studies in higher latitudes suggest a direct relationship between the quantity of TOM exported and runoff volume per unit area of watershed. A plausible explanation is that dissolved OM is the major form of OM in most running waters and varies less in magnitude than hydrologic runoff from one watershed to another.