Radionuclide activities and metal concentrations in sediments of the Sebou Estuary, NW Morocco, following a flooding event

Abstract

This study presents metal concentrations (Fe, Mg, Mn, Co, Cu, Zn, Pb, As, Sr and V) and radionuclide activities ((40)K, (137)Cs, (210)Pb, (226)Ra, (228)Ac, (234)Th and (212)Pb) in surface deposits and a sediment core from the Sebou Estuary, Northwest Morocco. Samples were collected in April 2009, about 2 months after a flooding event, and analysed using a well-type coaxial gamma-ray detector and inductively coupled plasma-quadrupole mass spectrometry. Activities of radionuclides and concentrations of almost all elements in surface samples displayed only moderate spatial variation, suggesting homogenous deposition of eroded local soil in response to intense precipitation. Excess (210)Pb displayed relatively constant activity throughout the sediment core, preventing dating and precluding determination of the historical accumulation rates of pollutants at the core site. Some elements showed non-systematic trends with depth and displayed local maxima and minima. Other elements presented relatively systematic concentration trends or relatively constant levels with discrete maxima and/or minima. Except for Mn, Sr and Cr, all metal concentrations in sediment were below levels typical of polluted systems, suggesting little human impact or losses of metals from sediment particles.

Natural and artificial radionuclides in a marine core. First results of 236 U in North Atlantic Ocean sediments

“…Specific activities of naturally occurring radionuclides 40 K, 210 Pb and 226 Ra in the core samples are shown in Table 2. The measured values are quite similar to those of typical marine sediments (Laissaoui et al, 2013;San Miguel et al, 2003;Villa et al, 2009). 226 Ra activity was fairly constant along the core, this is expected, since the deposition of 226 Ra from particle scavenging or redisolution from water is negligible and we are measuring the concentrations of 226 Ra naturally present in the sediment (see Table 2).…”

Environmental radioactivity and trace metals in surficial sediments from estuarine systems in Ghana (Equatorial Africa), impacted by artisanal gold-mining

“…Potasium-40 activity concentrations were in the range of values reported in scientific literature for estuarine environments (e.g., Laissaoui et al, 2013;Klubi et al, 2017) with a mean value significantly higher in the Ankobra Estuary (after a Fisher's LSD test, Table 1).…”

Sediment geochronology and spatio-temporal and vertical distributions of radionuclides in the Upper Bonny Estuary (South Nigeria)

“…Results from this work were seriously criticised and qualified as being impossible and improperly determined (Leopold and Gerstmann, 2009). Sediments in estuarine systems have been considered as the final fate of radionuclides, among other pollutants, and, therefore, their analysis provide more reliable assessment of radioactive pollution than that of water (Laissaoui et al, 2013). The reason is that the rate of change of pollutant concentrations in sediment is extremely slower than in water.…”