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Composition and cycling of colloids in marine environments
Author(s) -
Guo Laodong,
Santschi Peter H.
Publication year - 1997
Publication title -
reviews of geophysics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 8.087
H-Index - 156
eISSN - 1944-9208
pISSN - 8755-1209
DOI - 10.1029/96rg03195
Subject(s) - biogeochemical cycle , biogeochemistry , organic matter , environmental chemistry , dissolved organic carbon , environmental science , cycling , nutrient cycle , benthic zone , microbial loop , oceanography , phytoplankton , chemistry , nutrient , ecology , geology , biology , history , archaeology
Colloidal (COM) or macromolecular organic matter makes up a significant portion of the bulk dissolved organic matter (DOM) pool in aquatic environments. Because of their high specific surface areas and complexation capacities, marine colloids are of great importance not only in the global carbon cycle but also in the biogeochemical cycling of many particle‐reactive nuclides and trace elements in the ocean. However, the colloidal pool as a whole is still poorly understood and largely uncharacterized. Recently, cross‐flow ultrafiltration and other separation techniques, which have been successfully used to isolate marine colloids, combined with a multitracer approach, have greatly advanced our understanding of the cycling of COM and its associated trace elements in marine environments. In this paper we focus on recent developments on isotopic and elemental composition of colloids which allow organic matter cycling in marine environments to be constrained. Major sections review sampling techniques for aquatic colloids, concentrations and distribution of COM, biochemical and elemental (organic and inorganic) characterization, and stable isotopic ( 13 C and 15 N) and radioisotopic ( 14 C and 234 Th) characterization of marine colloids. We discuss sources and turnover rates of organic matter in the ocean, importance of benthic boundary layer processes in the cycling of DOM, changes in the paradigms of marine organic matter cycling, and research needs for a better understanding of the biogeochemistry of marine colloids.