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Environmental Assessment by Metallic Trace Elements of Gold Soils – Case of Chami (Dakhlet Nouadhibou, Mauritania)

El Hadi Sidi Mohamed, Hamoud Ahmed, Chakiri Said, El Hadi Hassan, Sabbar Mohamed Salem, Abdeina El Houssein, Baghdad Bouamar, Zerdeb Mohammed Amine, Vall Mohamed

Ecological Engineering & Environmental Technology

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2023

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Vol. 24, iss. 6

239--249

EN

In the Inchiri region of northern Mauritania, the discovery of new artisanal methods for extracting gold has made the town of Chami a strategic location for gold miners and their mining operations. Despite the importance of this activity in the country’s economy, to the significant revenues it provides, it is still likely to have a negative impact on the various environmental compartments. The objective of this study was to assess the environmental impact of trace metal elements (ETM) from gold panning in the soils of Chami area. For this purpose, forty soil samples were collected during a field mission in May 2022. The geochemical analyses of the ETM (As, Co, Cr, Cu, Hg, Pb, Ni and Zn) were carried out at the ALS laboratory in Dublin, using the inductively coupled plasma - atomic emission spectroscopy (ICP-AES) technique. The results show that the concentrations of ETM in soils differ according to the sampling station and the considered metal. These concentrations sometimes exceed the normal thresholds. The average value of the pollution index is higher than 1, revealing soil contamination by several elements (As, Cu, Hg and Pb). The geo-accumulation index varying between 0 and 4 shows a medium to high soil pollution class. The correlation matrix obtained shows positive correlations between the studied elements, which suggest that they have the same anthropic origin. These results show an accumulation of metals in soils that can persist in the environment, especially Hg, the most toxic element that is easy to diffuse and change speciation, in addition to being capable of causing risks to the environment and human health.

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Assessment of Groundwater Contamination by Trace Metals in the Chami Gold Area (Mauritania)

El Hadi Sidi Mohamed, Hamoud Ahmed, Chakiri Said, El Hadi Hassan, Abdeina El Houssein, Sabbar Mohamed Salem, Baghdad Bouamar, Vall Mohamed, Zerdeb Mohammed Amine, Dahi Sidi Mohamed

Ecological Engineering & Environmental Technology

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2023

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Vol. 24, iss. 7

139--147

EN

Artisanal gold mining in Chami is an important lever in the country economy, owing to the benefits it brings, but it is also likely to have a negative impact on various environmental compartments. Contamination of surface and ground water by trace metals elements (ETMs) was studied in the vicinity of the Chami gold processing center. The aim of the study was to assess the water contamination by trace metals (ETMs) in the town of Chami. Nine water samples (process and boreholes) were analyzed for (Co, Cr, Cu, Ni, Pb, Zn and Hg). The analysis was carried out by the DMA 80 technique for Hg at the ONISPA laboratory in Nouakchott and the other ETM at the Kenitra geosciences laboratory by the ICP-MS technique. The results of the analyses show that the ETM concentrations are high in process water samples and low in drilling water samples. Pollution indices and coefficients of variation indicate no contamination or anthropogenic traces in the borehole samples, but high levels of Hg and Ni in the process water. These results show the accumulation of metals in significant quantities in the process waters, especially Hg, proving that the waters of the mining waste basins at the Chami processing site are becoming sources of environmental pollution by mercury, which can be released into the environment by several pathways.

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Quantification and Evaluation of Water Erosion by RUSLE/GIS Approach in the Ykem Watershed (Western Morocco)

Aoufa Mohameden, Baghdad Bouamar, El Hadi Hassan, Chakiri Saïd, Hamoud Ahmed, Zoraa Noura, Zerdeb Mohammed Amine, Moussa Karima

Ecological Engineering & Environmental Technology

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2022

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Vol. 23, iss. 5

42--53

EN

The Water erosion of soils considered the main cause of soil degradation in Morocco. Soil erosion not only reduces agricultural productivity but also reduces water availability, and negatively contributes to the quality of drinking water sources. Consequently, the assessment of soil erosion risk has become the objective of several researches at the Moroccan level. It is in this context the purpose of this study is to assess the soil erosion risk using a Revised Universal Soil Loss Equation (RUSLE) / Geographic Information System (GIS) approach at the scale of the watershed of the Oued Ykem (western Morocco). (GIS) techniques were adopted to process the data obtained at the watershed scale, of reasonable spatial resolution (30 m) for the application of the RUSLE model. The latter is a multiplication of the five factors of erosion: the rainfall erosivity (R), the soil erodibility (K), the slope length and steepness (LS), the cover and management and the support practice (P). Each of these factors has been expressed as a thematic map. The Oued Ykem watershed is an elongated coastal basin with an area of 516 km2. It is part of the Atlantic coastal basins of western Morocco. It is located southwest of the city of Rabat. Oued Ykem is characterized by a semi-arid climate with oceanic influence. Rare and irregular rains, mostly stormy in nature, combined with deforestation, cause erosion and irregular flow. Its flow-rate increases during the winter. Extreme flows-rate can be recorded after exceptional and very intense showers upstream of the basin. The resulting soil loss map, with an average erosion rate varying from 0 to 54 t/ha/year, showed low erosion. Areas with a strong erosion rate exceeding 30 t/ ha/ year cover about 3.8 % of the basin area. The analysis of the erosion risk map, in comparison with the maps of the different factors in the equation, showed a clear and important influence of the vegetation cover on the soil erosion (C factor is from 0.03 to 0.9), followed by the topographic factor, especially the slope (LS factor varies from 0 to 56.71).

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Assessment of Heavy Metals Pollution in the Marine Sediments of the Lévrier Bay (Nouadhibou, Mauritania)

Yehdhih Maimouna, El Hadi Hassan, Baghdad Bouamar, Chakiri Saïd, Hamoud Ahmed, Zerdeb Amine, Moussa Karima

Ecological Engineering & Environmental Technology

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2022

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Vol. 23, iss. 5

84--90

EN

Geochemical study of twenty-seven marine sediments of the Levrier Bay used eleven heavy metals to display descriptive statistics and to assess the environmental impact of this industrial area. The analysis of eleven heavy metals (Pb, Zn, Cu, Ni, V, Cr, Co, Hg, Cd, As and Mo), major and other trace elements, were performed by ICP-MS. Pollution load Index (PLI) show low degree of contamination. Geochemical Index (Igeo) and enrichment Factor (EF) have been used to assess the environment quality at varied sites in sediments. Results display moderate concentrations for the most of elements excepted the As and Hg which often are upon the amount measured in the UCC baseline. The local presence Hg and As, limited to some sites of the area, allow to conclude that the sediments of the Lévrier Bay didn’t suffer from the human activities in the area.