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Quantifying fluxes and characterizing compositional changes of dissolved organic matter in aquatic systems in situ using combined acoustic and optical measurements
Author(s) -
Downing Bryan D.,
Boss Emmanuel,
Bergamaschi Brian A.,
Fleck Jacob A.,
Lionberger Megan A.,
Ganju Neil K.,
Schoellhamer David H.,
Fujii Roger
Publication year - 2009
Publication title -
limnology and oceanography: methods
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.898
H-Index - 72
ISSN - 1541-5856
DOI - 10.4319/lom.2009.7.119
Subject(s) - environmental science , estuary , dissolved organic carbon , wetland , forcing (mathematics) , sampling (signal processing) , flux (metallurgy) , particulates , aquatic ecosystem , colored dissolved organic matter , hydrology (agriculture) , atmospheric sciences , environmental chemistry , ecology , chemistry , geology , oceanography , phytoplankton , geotechnical engineering , organic chemistry , filter (signal processing) , computer vision , biology , nutrient , computer science
Studying the dynamics and geochemical behavior of dissolved and particulate organic material is difficult because concentration and composition may rapidly change in response to aperiodic as well as periodic physical and biological forcing. Here we describe a method useful for quantifying fluxes and analyzing dissolved organic matter (DOM) dynamics. The method uses coupled optical and acoustic measurements that provide robust quantitative estimates of concentrations and constituent characteristics needed to investigate processes and calculate fluxes of DOM in tidal and other lotic environments. Data were collected several times per hour for 2 weeks or more, with the frequency and duration limited only by power consumption and data storage capacity. We assessed the capabilities and limitations of the method using data from a winter deployment in a natural tidal wetland of the San Francisco Bay estuary. We used statistical correlation of in situ optical data with traditional laboratory analyses of discrete water samples to calibrate optical properties suited as proxies for DOM concentrations and characterizations. Coupled with measurements of flow velocity, we calculated long‐term residual horizontal fluxes of DOC into and out from a tidal wetland. Subsampling the dataset provides an estimate for the maximum sampling interval beyond which the error in flux estimate is significantly increased.