Organic carbon content and textural characteristics of sediments within the Chantuto-Panzacola coastal lagoons system, Chiapas

Abstract

Seasonal and spatial distribution of surface sediments from the Chantuto-Panzacola coastal lagoon system were analyzed, including organic carbon (O.C.) content, during the years 1997 to 2003. Surface sediments were taken from 10 sites by means of a small van Veen grab sampler (3L) and sediment composition (sand, silt and clay components) was obtained by pipette analysis. There were differences in the sediments O.C. inbetween dry and wet seasons, with higher levels corresponding to the latter and showing that O.C. contributions to the system come from autochthonous and allochthonous sources through fluvial drainage. O.C. levels throughout the lagoons were highest in stations 4 (Chantuto), 5 and 6 (Panzacola), while station 1 (the entrance, influenced by marine conditions) showed lower values. Sediment texture values were markedly heterogenous throughout years, seasons and stations. The effect of tropical storm Javier was found to be significant in incrementing the sand content in almost the entirety of the system, as well as decreasing the O.C. contents. The 2003 O.C. values were similar to those measured in 1997; on the other hand, continuous change in grain size has been the norm, affecting mainly those areas where dredging activities have taken place since 2001.