Role of natural organic matter in governing the bioavailability of toxic metals to American Oysters (Crassostrea virginica) /
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| Format: | Thesis eBook |
| Language: | English |
| Published: |
[College Station, Tex.] :
[Texas A&M University],
[2006]
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| Subjects: | |
| Online Access: | Link to OAK Trust copy |
| Abstract: | Colloidal macromolecular organic matter (COM), which makes up a large portion of the bulk dissolved organic matter (DOM) in marine environments, has the capability to modify the bioavailability of potentially toxic metals to aquatic organisms. In order to better understand the bioavailability of some of these metals to estuarine bivalves, American Oysters (Crassostrea virginica) were exposed to different types of natural colloidal (COM) and model (alginic acid, carrageenan, and latex particles) organic biopolymers, tagged with gamma-emitting radioactive metal ions (¹¹⁰[superscript m]Ag, ¹⁰⁹Cd, ⁵⁷Co, ⁵¹Cr, ⁵⁹Fe, ²⁰³Hg and ⁶⁵Zn) or ¹⁴C (to sugar OH groups). Natural COM was obtained from Galveston Bay water by 0.5 [mu] m filtration, followed by cross-flow ultrafiltration, using a 1kDa ultrafilter, diafiltration and freeze-drying. COM and DOM model compounds were used in the bioavailability experiments at 2 ppm concentrations. Separate 16-hour experiments using varying sizes of latex particles assessed the lowest size of colloids that can be filtered from the water. Results showed that filter-feeding bivalves could efficiently remove particles as small as 0.04[mu]m (40nm) in diameter, with removal half-times of 2.5 to 5.5 hours, equivalent to filtration rates of about 50 ± 15 ml/hour, or about 3 L d⁻¹ g⁻¹, which are typical values for these oysters. Results of the 20-hour bioavailability experiments demonstrated that oysters could effectively filter metals bound to COM, with the metals bound to alginic acid COM being removed at the highest rates from the water. However, the metals bound to alginic acid were not found in oyster meat in the highest amounts: it was the metals associated with the carrageenan COM. The ¹⁴C labeled biopolymer data also showed alginic acid to be removed from the water at the highest rate and, contrary to the metals, was also present in the meat in the greatest amounts. Thus, while previous experiments suggested that the quantity (i.e., concentration) of natural organic matter is important for metal bioavailability, it was shown here that the "quality", i.e., the type of natural organic matter, is also a factor for controlling bioavailability, removal and incorporation rates of metals to oysters. |
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| Item Description: | "Major Subject: Oceanography" Title from author supplied metadata (automated record created on Sep. 15, 2006.) Vita. Abstract. Electronic resource. |
| Format: | Mode of access: World Wide Web. System requirements: World Wide Web access and Adobe Acrobat Reader. |
| Bibliography: | Includes bibliographical references. |