Spatial and seasonal variations and ecotoxicological significance of sediment trace metal concentrations in Kebir-Rhumel basin (Northeast of Algeria)

Abstract

This study sought to assess sediment contamination by trace metals (cadmium, chromium, cobalt, copper, manganese, nickel, lead and zinc), to localize contaminated sites and to identify environmental risk for aquatic organisms in Wadis of Kebir Rhumel basin in the Northeast of Algeria. Water and surficial sediments (0-5 cm) were sampled in winter, spring, summer and autumn from 37 sites along permanent Wadis of the Kebir Rhumel basin. Sediment trace metal contents were measured by Flame Atomic Absorption Spectroscopy. Trace metals median concentrations in sediments followed a decreasing order: Mn > Zn > Pb > Cr > Cu > Ni > Co > Cd. Extreme values (dry weights) of the trace metals are as follows: 0.6-3.4 microg/g for Cd, 10-216 microg/g for Cr, 9-446 microg/g for Cu, 3-20 microg/g for Co, 105-576 microg/g for Mn, 10-46 microg/g for Ni, 11-167 microg/g for Pb, and 38-641 microg/g for Zn. According to world natural concentrations, all sediments collected were considered as contaminated by one or more elements. Comparing measured concentrations with American guidelines (Threshold Effect Level: TEL and Probable Effect Level: PEL) showed that biological effects could be occasionally observed for cadmium, chromium, lead and nickel levels but frequently observed for copper and zinc levels. Sediment quality was shown to be excellent for cobalt and manganese but medium to bad for cadmium, chromium, copper, lead, nickel and zinc regardless of sites.

Safety and efficacy of manganese compounds (E5) as feed additives for all animal species: manganous carbonate; manganous chloride, tetrahydrate; manganous oxide; manganous sulphate, monohydrate; manganese chelate of amino acids, hydrate; manganese chelate of glycine, hydrate, based on a dossier submitted by FEFANA asbl

“…The PEC sed was calculated to be 21.2 mg/kg wet weight, which substantially exceeds the threshold for Phase I assessment (10 μg/kg). However, manganese concentrations in top sediment in marine and estuarine environments vary widely from 10 to at least 4,000 mg/kg, which in all cases by far exceeds that maximally emitted from aquaculture (Sadiq and Zaidi, 1985;Cahill and Unger, 1993;Galasso et al, 2000;Sahli et al, 2011). For land-based aquaculture operations, such as ponds and raceways, the surface water downstream of the fish farm is considered the most sensitive compartment (EFSA, 2008b).…”

Assessment of metal contamination in soil banks of the Rhumel wadi (Northeast Algeria)

“…Indeed, Sahli et al (2011) recorded similar values in sediments from unaffected sites of Rhumel Wadi.…”

“…This increase is probably mainly induced by intensive vehicle traffic and emissions of some industrial complexes related to urban and A c c e p t e d M a n u s c r i p t 5 industrial areas in the Rhumel subbasin. Sahli et al (2011) reported that the sediment quality of Rhumel Wadi in this part is medium to poor for the studied metals (Sahli et al 2012).…”

“…In previous studies significant enrichment of metals in the Rhumel subbasin was observed. This included cases of lead enrichment in soils of wadi banks (Krika, Rached, and Du Laing 2013) and Cd, Co, Cr, Cu, Pb and Zn enrichment in water and sediment of this wadi (Afri-Mehennaoui, Sahli, and Mehennaoui 2004;Sahli et al 2011Sahli et al , 2012. The soil banks of Rhumel Wadi could be discharging appreciable quantities of wastes from urban and industrial areas.…”

Scientific Opinion on the safety and efficacy of manganese compounds (E5) as feed additives for all animal species: manganous oxide, based on a dossier submitted by Poortershaven Industriële Mineralen B.V.

“…However, manganese concentrations in top sediment in marine and estuarine environments vary widely from 10 to at least 4000 mg/kg, which in all cases far exceeds that maximally emitted from aquaculture (Sadiq and Zaidi, 1985;Cahill and Unger, 1993;Galasso et al, 2000;Sahli et al, 2011). When fed to fish in seacages, the sediment under the cage is considered the compartment of concern (EFSA, 2008b).…”