“…The composition of gneisses and silico-calcic rocks is similar to that of a sedimentary sequence that contains pelites, grawackes, dolomites, evaporites and iron-rich sediments ( Nzenti, 1998 ). The soils are mostly red or yellow ferralsols developed on metamorphic rocks ( Ndjigui et al., 2013 ), and gleysols occur in the valleys ( Ekoa Bessa et al., 2018b ). Figure 1 Investigated area and sampling location: a) Location of Cameroon in Africa; b) Location of the study area in Cameroon; c) Mefou watershed; d) Mefou River in Yaoundé and its urban area.…”
Section: Methodsmentioning
confidence: 99%
“…Five cores were collected along the Mefou River at Totoli, Onambele, Akomnyada, Etoa, and Ahala. The sampling was manually conducted using polyvinyl chloride pipe in a raft as described by many authors (e.g., Ekoa Bessa et al., 2018a , b ; N'nanga et al., 2019 ). For all cores, sampling was done at each 10 cm interval.…”
Section: Methodsmentioning
confidence: 99%
“…Rivers and streams directly receive about 50% of the total pollution caused by human activities ( Ekengele et al., 2008 ). Recent studies on the pollution of aquatic systems by trace metals in Cameroon are mostly focused in mining areas and rarely on rivers in rural or urban areas across the country ( Ekengele et al., 2008 ; Tehna et al., 2015 ; Mimba et al., 2018 ; Ekoa Bessa et al., 2018a , b ; Mandeng et al., 2019 ; Tehna et al., 2019 ). There are several punctual sources of industrial pollution in Cameroon.…”
This study focuses on risk assessment of Cr, V, Ni, Co, Pb, Cu, and Zn in the Mefou River sediments located at Yaoundé, West-Africa. Sediment samples were collected from five stations in the downstream of the Mefou River, which drains the urban area of Yaoundé between latitudes 3°30′ and 3°58′ North and longitudes 11°20′ and 11°40′ East. The geochemistry data were analyzed statistically and the pollution indices were calculated in order to identify and estimate the sources of metal contamination in the Mefou River sediments. The results obtained show that the average concentrations of trace metals are almost higher than those of the upper continental crust (UCC) and the metal average in the Simbock Lake cores. However, the concentrations of Ni, Cu, Pb, and Zn in sediments located in most urbanized sites are lower than those of the UCC and the average of Simbock Lake sediments. The pollution indices such as enrichment factor (EF), geo-accumulation index (Igeo), and pollution load index (PLI) showed that trace metals were mainly influenced by human sources, except for Pb, Cu, and Zn, which stemmed from natural sources. The sediments of the Mefou River would therefore be affected with low to moderate pollution levels. The low values of potential ecological risk (RI: 22.36–41.53) suggest a low potential ecological risk effect. The multivariate statistical analysis indicates that Ni, Cu, Pb, Co, and Zn have been derived mainly from natural sources, while V and Cr would partially derive from human activities. The results of this research can be a reference for trace metal pollution along an African urbanized river corridor. This can be considered as an act of prevention of urban watercourses in Cameroon and in other parts of the world, especially in major African urban metropolis.
“…The composition of gneisses and silico-calcic rocks is similar to that of a sedimentary sequence that contains pelites, grawackes, dolomites, evaporites and iron-rich sediments ( Nzenti, 1998 ). The soils are mostly red or yellow ferralsols developed on metamorphic rocks ( Ndjigui et al., 2013 ), and gleysols occur in the valleys ( Ekoa Bessa et al., 2018b ). Figure 1 Investigated area and sampling location: a) Location of Cameroon in Africa; b) Location of the study area in Cameroon; c) Mefou watershed; d) Mefou River in Yaoundé and its urban area.…”
Section: Methodsmentioning
confidence: 99%
“…Five cores were collected along the Mefou River at Totoli, Onambele, Akomnyada, Etoa, and Ahala. The sampling was manually conducted using polyvinyl chloride pipe in a raft as described by many authors (e.g., Ekoa Bessa et al., 2018a , b ; N'nanga et al., 2019 ). For all cores, sampling was done at each 10 cm interval.…”
Section: Methodsmentioning
confidence: 99%
“…Rivers and streams directly receive about 50% of the total pollution caused by human activities ( Ekengele et al., 2008 ). Recent studies on the pollution of aquatic systems by trace metals in Cameroon are mostly focused in mining areas and rarely on rivers in rural or urban areas across the country ( Ekengele et al., 2008 ; Tehna et al., 2015 ; Mimba et al., 2018 ; Ekoa Bessa et al., 2018a , b ; Mandeng et al., 2019 ; Tehna et al., 2019 ). There are several punctual sources of industrial pollution in Cameroon.…”
This study focuses on risk assessment of Cr, V, Ni, Co, Pb, Cu, and Zn in the Mefou River sediments located at Yaoundé, West-Africa. Sediment samples were collected from five stations in the downstream of the Mefou River, which drains the urban area of Yaoundé between latitudes 3°30′ and 3°58′ North and longitudes 11°20′ and 11°40′ East. The geochemistry data were analyzed statistically and the pollution indices were calculated in order to identify and estimate the sources of metal contamination in the Mefou River sediments. The results obtained show that the average concentrations of trace metals are almost higher than those of the upper continental crust (UCC) and the metal average in the Simbock Lake cores. However, the concentrations of Ni, Cu, Pb, and Zn in sediments located in most urbanized sites are lower than those of the UCC and the average of Simbock Lake sediments. The pollution indices such as enrichment factor (EF), geo-accumulation index (Igeo), and pollution load index (PLI) showed that trace metals were mainly influenced by human sources, except for Pb, Cu, and Zn, which stemmed from natural sources. The sediments of the Mefou River would therefore be affected with low to moderate pollution levels. The low values of potential ecological risk (RI: 22.36–41.53) suggest a low potential ecological risk effect. The multivariate statistical analysis indicates that Ni, Cu, Pb, Co, and Zn have been derived mainly from natural sources, while V and Cr would partially derive from human activities. The results of this research can be a reference for trace metal pollution along an African urbanized river corridor. This can be considered as an act of prevention of urban watercourses in Cameroon and in other parts of the world, especially in major African urban metropolis.
“…Gold mining could also be the cause of soil infertility, as a result of the erosion of the organo-mineral layer. The soils are then destroyed, and therefore not suitable for agriculture ( Figure 4d) [36][37][38].…”
Section: Destruction Of Vegetation Covers (Deforestation)mentioning
confidence: 99%
“…Similar results are obtained for average Cr (192.5 mg/kg) and Ni (64 mg/kg) values in soil at Bedobo site (Table 1). Low concentrations of heavy metals and radioactive elements can be linked to leaching of source rocks [16,36,38]. According to the WHO and UNICEF [39], the mean heavy metal concentrations in the Betare-Oya soils and tailings are under the agricultural, residential and industrial limits for environmental health.…”
Section: Heavy Metals In Betare-oya Mining Areamentioning
This study includes soils and tailings from the gold mine of four stations (Mari, Mbigala, Mboufa and, Bedobo) in Betare-Oya, eastern Cameroon. These stations have been utilized by Cameroonians and later on by some companies. Soils and tailings were sampled and heavy metal (Cr, V, Ni, Cu, Zn, Hg and, Pb) and radioactive element (Th and U) contents have been determined using ICP-MS techniques. This work deals with the heavy metaldistribution in mining waste and surrounding soils and tailings.The study area is exposed to artisanal gold mining activities. Field observations revealed the soildestructionas well as the environment.All metal values fall below the average shale, except Cr who's the content is higher than the shale value in soils and tailings. Lead and Th values are above the average shale in tailings. Heavy metal pollution was performed using pollution indices such as enrichment factor (EF), geo-accumulation index (I-geo) and pollution load index (PLI). The overall results reveal that the soils and tailing from Betare-Oya mining area, Eastern Cameroon are only polluted by Cr. These sediments have minor to moderate enrichment; they are unpolluted to moderately polluted with a low contamination level for other metals. Only two stations can be considered as slightly polluted, with minor enrichment and moderate contamination by metals.
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