| Abstract: | Suspended matter in the Gulf of Mexico and northern Caribbean Sea is characterized with respect to its mass distributions, particle size distributions, biological components, and its seasonal variations in this study. Electron microscopy was used extensively in characterizing the suspended matter. The spatial distribution of total suspended matter in the northwestern Gulf of Mexico is quite different from that in the Yucatan-Florida Straits region of the Gulf of Mexico. This is the result of river discharges into the northern Gulf of Mexico, and inflow of Caribbean water which has a low total suspended matter content into the Yucatan-Florida Straits region. The average concentration of total suspended matter in water deeper than 100 meters was found to be 233 μg/1 in the northwestern Gulf of Mexico, 122 μg/1 in the Yucatan-Florida Straits Region, and 47 μg/1 in the northern Caribbean Sea. The mass distribution in the Gulf of Mexico was bimodal due to seasonal variations. The size distribution of suspended particles was measured at one station in the Gulf of Mexico and found to be continuous between 5 and 0.05 μm, and had the relationship N = 1.50X10⁷D[superscript -2.52]. Thirty seven different forms of coccoliths were observed in the suspended matter, 13 of which have been previously reported in the Gulf of Mexico. An attempt was made to estimate a "gross" settling rate for total suspended matter by measuring ²³⁴Th disequilibrium. However, 35 to 85% of the ²³⁴Th was not associated with particles retained on 0.45 μm Millipore filters. This unexpected behavior prevented a meaningful estimate from being made. The distribution, transport, and interaction of suspended matter with sea water was found to be very complex. |
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