Geochemistry, chemical speciation and environmental impact of trace and rare earth elements

The study of hydrogeochemical processes, chemical speciation using rare earth elements done using groundwater samples in Oban Massif and Mamfe Embayment southeastern Nigeria. Water samples were collected from boreholes, streams, springs and river sources. Physical parameters such as hydrogen ion index (pH), redox potential (eH), electrical conductivity (EC), total dissolved solids (TDS) and turbidity) were measured insitu using standard equipment. Anions such as nitrate (NO3-), sulfate (SO42-), bicarbonate (HCO3-), phosphate (PO43-), and chloride ( Cl-) were measured in the laboratory using titration and chromatography, major cations (magnesium,(Mg2+), calcium (Ca2+), potassium (K+), sodium (Na+)) were analyzed using inductively coupled plasma argon emission spectrometry while trace and rare earth elements were assayed using inductively coupled plasma mass spectrometry. Chemical speciation modeling for solution complexation and saturation indices was done using the software VISUAL-MINTEQ 3.1. In surface water both light and heavy rare earth elements minerals of phosphate ligand were supersaturated.