Spatiotemporal Distribution and Sources of Trace Elements in Ave River (Portugal) Lower Basin: Estuarine Water, Sediments and Indigenous Flora.

This study aimed to assess the spatial and seasonal distribution and anthropogenic sources of trace elements (Li, Be, Al, V, Cr, Co, Ni, Cu, Zn, Se, Mo, Ag, Cd, Sb, Ba, Tl, Pb, and U) by ICP-MS in the Ave River lower basin, Portugal. Mean values (µg L⁻¹) of Al (2384), Zn (55.3), Se (34.6), Cu (24.7), Pb (12.7), Ag (0.75), and Cd (0.66), exceeded the water quality guidelines for the protection of aquatic life. The decreasing order of trace elements concentrations in surface water and sediments was, respectively: Al > Zn > Se > Mo > Li > Ba > V > Cu > Pb > Ni > Cr > U > Be > Co ≈ Sb > Ag ≈ Cd > Tl; and Al > Zn > Li > Ba > Cu > Pb > Cr > V > Ni > Co > U > Be > Se ≈ Mo ≈ Tl ≈ Cd ≈ Sb ≈ Ag. Moreover, the concentrations of nitrate values were higher than 50 mg L⁻¹. To distinguish natural from anthropogenic sources, the geo-accumulation index (I_geo) and the enrichment factor (EF) of sediments were determined. I_geo revealed high contamination by Al, Mn, Ba and Zn, while EF evidenced enrichment for Se, Cd, Zn, Li, Cu, Ag, Pb and U. Bioaccumulation factors (BF) in flora suggested that macroalgae, Medicago marina L. and Plantago lanceolata L., might be accumulators of Se, Mo, Ba and Pb (BF > 1). The highest translocation factor (TF) was found for Mo in leaves (33.6) and flowers (28.1) of P. lanceolata L.. Article Highlights: The present work regards a comprehensive study on the occurrence, spatial distribution, possible sources and bioaccumulation of trace elements in this ecosystem, namely in water, sediments and native local flora (plants and macroalgae). In fact, various studies have demonstrated the high anthropogenic pressure of Ave River estuary, the presence of several classes of pollutants and the negative impacts in local aquatic organisms. Nevertheless, there are no studies regarding the monitoring of a large panel of trace elements considering three different matrices (water, sediments and plants) and their possible correlation Pollution indices such as geo-accumulation (Igeo) and enrichment factor (EF) were also determined to investigate sources of these elements. Igeo revealed high contamination by Al, Mn, Ba and Zn, while EF evidenced enrichment for Se, Cd, Zn, Li, Cu, Ag, Pb and U. Bioaccumulation factors (BF) in flora suggested that macroalgae, Medicago marina L. and Plantago lanceolata L. might be accumulators of Se, Mo, Ba and Pb These monitoring data are important to alert local and national authorities to take actions and decisions to protect and improve water quality of Portuguese waterbodies and meet national and European requirements [ABSTRACT FROM AUTHOR]