Fibrillar polysaccharides in marine macromolecular organic matter as imaged by atomic force microscopy and transmission electron microscopy
- Univ. of Geneva (Switzerland)
- Texas A and M Univ., Galveston, TX (United States). Dept. of Oceanography
A consensus is now emerging that the structure of organic macromolecules will determine their function in aquatic systems. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) are highly complementary techniques for the study of natural colloids and can, when used together, reveal complementary information about the relative abundance and structures of aquatic macromolecules and colloids. In this study, colloid samples from the Gulf of Mexico and Middle Atlantic Bight of nominal sizes 1--200 nm were collected by cross-flow ultrafiltration, diafiltered, and freeze-dried. Rehydrated colloids were analyzed in parallel by AFM and TEM using standardized techniques. Results from estuarine, surface-, and deep-water samples show that an important fraction of colloidal organic matter (COM) consists of fibrillar material, which is rich in polysaccharides and fresher (i.e., has a younger radiocarbon age) than the bulk COM. This result is important because COM makes up 30--70% of oceanic and estuarine nominally dissolved organic matter. Other microparticles appear to be quasi-spherical, often attached to the fibrils like pearls. In the surface waters of the Gulf of Mexico, Middle Atlantic Bight, and Trinity River, fibrils with diameters of 1--3 nm and lengths of 100--2,000 nm were predominant. Although fibrils were also observed in samples from the benthic nepheloid layer in the Gulf of Mexico (1,600 m) and Middle Atlantic Bight (2,600 m), a much greater heterogeneity of colloid and macromolecule shapes and sizes was observed in these deeper waters.
- Sponsoring Organization:
- Swiss National Science Foundation, Bern (Switzerland); Office of Naval Research, Washington, DC (United States); USDOE, Washington, DC (United States); National Science Foundation, Washington, DC (United States)
- DOE Contract Number:
- FG03-92ER61421
- OSTI ID:
- 655498
- Journal Information:
- Limnology and Oceanography, Vol. 43, Issue 5; Other Information: PBD: Jul 1998
- Country of Publication:
- United States
- Language:
- English
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