Geochemical partitioning of lead in biogenic carbonate sediments in a coral reef depositional environment

Environmental Geochemistry of Anthropogenic Lead in Estuarine Sediments of the Jamapa River, Mexico

The combustion of alkyl-lead gasolines was the primary anthropogenic source of Pb in the second half of the twentieth century. Previously deposited Pb-aerosols enriched the organic matter and Fe-oxi-hydroxides phases of soils, which long after continue being transported downstream to be an important source of Pb into the ocean. Geochemical partition of Pb was determined in estuarine sediments of the Jamapa River, southern Gulf of Mexico, by the Tessier's sequential extraction protocol. The residual fraction, conformed by siliciclastic particles, contain the highest proportion of Pb (8.6 μg/g = 70%), been the main source into the ocean. However, as the organic carbon and Fe,MnO(OH) fractions, together summed the 26% of total Pb in samples, so, it is assumed that previously deposited anthropogenic Pb, from alkyl-lead gasolines, still is an important source of this element, that is transported by the Jamapa River, enriching the coastal area.

Heavy Metals in Muscle Tissue of Pterois volitans from the Veracruz Reef System National Park, Mexico

Concentrations of cadmium (Cd), lead (Pb), vanadium (V), and zinc (Zn) were measured in the muscle of 30 specimens of Pterois volitans, captured on April 2018, in the Veracruz Reef System National Park (VRSNP), Veracruz, Mexico. Concentrations, in the samples, were quantified with atomic absorption spectrophotometry (AAS), after microwave digestion. Results of the mean concentration, in descending order were V = 7.3 ± 0.7; Pb = 0.66 ± 0.07; Zn = 0.43 ± 0.14; and Cd = 0.03 ± 0.01 mg kg⁻¹ dry weight. These values did not exceeded limits established in the Mexican National Standard (NOM-242-SSA1-2009), of Cd and Pb (0.5 mg kg⁻¹) wet weight. This means that consumption of lionfish from this site does not pose a potential risk for human health.

Distribution of the bioavailable and total content of copper and lead, in river sediments of the Jamapa-Atoyac fluvial system, Mexico

The Jamapa-Atoyac fluvial system (JAFS) is tropical river system, which flows from the Pico de Orizaba, the highest elevation in Mexico, to end in the city of Veracruz, in the southern Gulf of Mexico. The geology of the watershed is dominated by Tertiary igneous rocks and Cretaceous limestones in the upper basin, and Quaternary alluvial sediments in the lower basin. Seventy percent of the land in the watershed has been deforested, and there are various urban and industrial areas. The JAFS is been widely known as source of trace elements to the coastal zone, and considered as contaminated. So, the aim of this study was to assess the environmental quality of the JAFS, using the total (TC) and the bioavailable (BF) concentrations of Cu and Pb, in surface fluvial sediments samples, in the dry (DS) and rainy (RS) seasons of the 2016. Average concentrations and ranges for the JAFS were Cu_T 10.2 ± 5.2 μg/g (2.2-41.5 μg/g); Cu_B 1.1 ± 1.4 μg/g (0.04-10.7 μg/g); Pb_T 5.0 ± 1.2 μg/g (1.8-10.9 μg/g); and Pb_B 0.7 ± 0.4 μg/g (0.1-2.0 μg/g). The BF only accounts for the ~ 10% of the total concentration for both elements, and is highly correlated to the mud content. No differences in average concentrations were found between the upper and lower bassins, nor among areas with different lithology. Cu presented higher concentrations during the RS, which suggest an enrichment of fluvial sediments from soil erosion, contrary, to Pb with higher concentrations during the DS. Although, some sampling stations, those located immediately after the Cordoba and Miguel Aleman cities, presented higher than average Cu and Pb concentrations, they did not exceeded the limits established by national environmental regulations, sediment quality guidelines, geoaccumulation index, and potential ecological risk indexes. Hence, the JAFS may be considered as not contaminated by Cu and Pb.