Suspended sediments in the southeastern Gulf of Mexico

Abstract

Suspended sediment concentration was determined from samples collected during oceanographic cruises dinamo I and dinamo II, aboard the R/V Justo Sierra in the southeastern Gulf of Mexico, during dry and north wind climatic periods in 1990. The average suspended matter concentration was 5.1 mg/l for the dry period and 5.5 mg/l for the period with a northern wind. The maximun value was 25.2 mg/l on dinamo II cruise and was obtained off the Grijalva and Usumacinta rivers, as well as the maximun observed during dinamo I. The suspended sediment is composed mainly of silt and clay particles toward the terrigenous zone and silicious organic debris and tar balls toward the offshore carbonate region. The relative abundance of elements in samples from the terrigenous and transitional zones reflects the influence of fluvial fine sediments by cationic elements of argillaceous origin. Sigma- t distribution patterns show the presence of a current coming from the north of Yucatan Peninsula, which penetrates in the study area parallel to the isopycnals. CTD data, satellite images, Ca/Al distributions and suspended sediments distributions suggest that off the Grijalva-Usumacinta mouth the direction of the current is eastward. Lower concentrations of total suspended matter are located seaward Terminos Lagoon and are apparently associated to a cyclonic circulation zone.