Distribution of Selenium, Molybdenum and Uranium in Sediment Cores from the Colorado River Delta, Baja California, Mexico

Abstract

The distribution of selenium, molybdenum and uranium was studied in ~1.5 m sediment cores from the Colorado River delta, at the Colorado (CR) and Hardy (HR) riverbeds. Core HR2 showed highest Se, Mo and U concentrations at its bottom (2.3, 0.95 and 1.8 μg g(-1)) within a sandy-silt layer deposited prior to dam construction. In CR5 the highest concentrations of these elements (0.9, 1.4 and 1.7 μg g(-1) respectively) were located at the top of the core within a surface layer enriched in organic carbon. A few samples from HR2 had Se above the probable toxic effect level guidelines.

Occurrence and Distribution of Uranium in a Hydrological Cycle around a Uranium Mill Tailings Pond, Southern China

“…The second was the pH values, since average pH value was 4.2 in the surface layer and turned to 6.43 at the bottom where the migration of U was hindered. The third one was the presence of organic matters [27,28]. Organics can adsorb U effectively, although desorption may occur due to competition between mineral surface sites and dissolved ligands [29].…”

The Importance of Analytical Chemistry in Environmental Geochemistry Studies in Mexico

“…In northwestern Mexico, Orozco-Durán et al [39] evaluated the distribution of Se, Mo, and U in sediment cores of around 1.5 m in length collected at the Colorado River delta, close to the Mexican-US frontier. ICP-MS was used to analyze the elements concentrations, organic carbon was analyzed with an infrared (IR) LECO elemental analyzer, and grain size was examined with a laser grain size analyzer.…”