Mercury in Biota and Surficial Sediments from Coatzacoalcos Estuary, Gulf of Mexico: Distribution and Seasonal Variation

Abstract

Variation of mercury (Hg) in sediments and biota from Coatzacoalcos estuary during the dry, rainy and windy seasons was estimated. In sediments, Hg concentrations ranged from 0.07 μg g −1 in site 13 (Ixhuatepec) located upstream, to 1.06 μg g −1 in site 3 (Coatzacoalcos river), located in the industrialized area. Highest enrichment factor (EF) and index of geoaccumulation (I geo ) in surficial sediments were 53 and 5.1 respectively. From EF and I geo , it is considered that Coatzacoalcos estuary is from moderately contaminated to contaminated. In most fish species from Coatzacoalcos estuary, the sequence of Hg concentration was liver>muscle>gills. Average Hg concentrations in soft tissue of bivalves ranged from 0.09 μg g −1 in Corbicula fluminea to 0.18 μg g −1 in Polymesoda caroliniana. Biota-sediment accumulation factor (BSAF) ranged from 0.9 in P. caroliniana during the rainy season (site 4) to 3.8 in P. caroliniana from the same site during the windy season.

A Preliminary Study of the Distribution and Mobility of Mercury in Water and Sediments From the San Juan River Watershed, Nuevo Leon Mexico

“…Total Hg concentrations ranged from 0.289 to 0.501 mg/Kg with a mean value of 0.405 ± 0.074 mg/Kg. As compared with other waterbodies, Hg concentrations in the San Juan River watershed sediment samples were higher than the concentrations of Hg reported in the Coatzacoalcos estuary (0.07-1.06 mg/Kg) [14]. However, a lower level of Hg in sediment samples was reported in the Papaloapan River Basin located in southern Veracruz, Mexico (0.027-0.090 mg/Kg) [12].…”

“…Worldwide contamination of Hg has been reported in aquatic systems [6][7][8][9][10][11], including contamination in Mexico [12][13][14]. However, no data has been published concerning the distribution of Hg contamination in the San Juan River watershed ecosystem.…”

Heavy metals in the habitat and throughout the food chain of the Neotropical otter, Lontra longicaudis, in protected Mexican wetlands

“…The wet and nortes seasons increase the dilution of contaminants but can also transport greater amounts of the contaminants from the highlands to the lower basin (Moreno-Casasola et al 2006;Ruelas-Inzunza et al 2009). This could explain the high concentrations of Hg tot and Cd measured in fish during this season.…”

“…Land use (and the associated use of water) in the upper sections of a basin affects the amount of heavy metals running throughout the river to the lower sections (Chen et al 2009;Ruelas-Inzunza et al 2009). The amount, however, changes throughout the year (Ruelas-Inzunza et al 2009) due to variations in the volume of the stream or river (about half the concentration of Hg tot and Pb during the rainy season compared with the dry season).…”

“…The amount, however, changes throughout the year (Ruelas-Inzunza et al 2009) due to variations in the volume of the stream or river (about half the concentration of Hg tot and Pb during the rainy season compared with the dry season). This may result in a differential risk of poisoning throughout the year for the organisms living in the lower sections of a river.…”