Particulate Matter Fluxes in Cuenca Alfonso During 2002-2005
Abstract
Time-series sediment trap data were collected between 2002 and 2005 from Cuenca Alfonso, a 400m-deep basin in Bahía de La Paz, a large embayment on the southwestern coast of the Gulf of California. Despite the lack of significant land drainage in this semi-dessert environment, terrigenous material, probably wind-born, dominates the sinking particulate matter. Peak lithogenic fluxes appear to be associated with higher frequencies of wind gusts stronger than 5 ms-1. Total mass flux fluctuated from week to week, and between years, averaging 277 gm-2y-1, essentially the same as radiometrically-determined accumulation rates of about 0.4 mmy-1 in cores of the underlying sediment. In 2003, the passage of 2 hurricanes induced high winds and flash flooding and the total mass flux offshore remained very high for two weeks following each event. This unusual sedimentation was equivalent to that of a full year without hurricanes and such events may account for some of the laminations found in cores. During most of 2005, on the other hand, sedimentation rates were lower than average. Although fluxes of all components tended to be highest during late fall and early winter, biogenic fluxes displayed peaks during all seasons of the year in Cuenca Alfonso. This is in contrast to the strong seasonal alternation between terrigenous sedimentation and diatom blooms observed in Guaymas Basin in the central Gulf. Furthermore, calcium carbonate dominated over biogenic silica within the marine component. Average annual fluxes of CaCO3, biogenic silica and POC were 52.5, 32.5 and 13.9 gm-2y-1, respectively.
- Publication:
-
AGU Spring Meeting Abstracts
- Pub Date:
- May 2007
- Bibcode:
- 2007AGUSMOS32A..03S
- Keywords:
-
- 4200 OCEANOGRAPHY: GENERAL;
- 4262 Ocean observing systems;
- 4277 Time series experiments (1872;
- 3270;
- 4475);
- 4800 OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL (0460);
- 4806 Carbon cycling (0428)