Distribution, Speciation, and Extractability of Cadmium in the Sedimentary Phosphorite of Hahotoé-Kpogamé (Southern Togo)

Gnandi, Kissao; Boroon, Mohammad Hassan Rezaie; Dimitri, Deheyn D.

doi:10.1007/s10498-009-9062-7

Cited by 10 publications

(4 citation statements)

References 17 publications

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“…German, British, and French were among the colonists that made the city a major port and world-renowned trading and commercial center (Nilsson 2002). The city has a nearby oil refinery and phosphate mine, which bring businesses yet are associated with critical environmental issues (Gnandi et al 2009;Gnandi and Tobschall 1999), and in addition to exporting various agricultural goods (coffee, copra, cocoa), tourism is another growing industry beneficial for the city.…”

Section: Introductionmentioning

confidence: 99%

Increased Bioavailability of Mercury in the Lagoons of Lomé, Togo: The Possible Role of Dredging

Gnandi

Han

Rezaie-Boroon

et al. 2010

AMBIO

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Surface sediments of the lagoons of Lomé, Togo, were analyzed for mercury, methylmercury, and trace elements. Concentrations were greater than typical for natural lagoon sediments, and with greater variability within the Eastern lagoon compared to the Western one. The Eastern lagoon is larger and has been dredged in the past, while the Western lagoon, which also receives major waste inputs, has not been dredged and shows less tidal flushing. Accordingly, one naturally believes that the Eastern lagoon is cleaner and probably safe to use due to its natural resources, including fishes to eat. Unexpectedly, we describe here that mercury methylation was greater in the Eastern lagoon, indicating increased bioavailability of mercury, as probably facilitated by past dredging that decreased solidphase retention of inorganic mercury. Urbanization has historically been more developed in the southern part of the lagoons, which is still reflected in contamination levels of sediment despite dredging, probably because sources of contamination are still more important there today. Such urban contamination emphasizes the need to regulate waste discharges and possible airborne contamination in growing cities of developing countries, and implements environmental and public health monitoring, especially in relation to misbelieves systematically associated with the cleansing effect of dredging activity.

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Section: Introductionmentioning

confidence: 99%

Increased Bioavailability of Mercury in the Lagoons of Lomé, Togo: The Possible Role of Dredging

Gnandi

Han

Rezaie-Boroon

et al. 2010

AMBIO

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“…They also examined the stress and displacement changes under the combined impacts of open-pit and underground mining. Researchers in other countries mainly studied the influence of phosphorite mining on the environment (Abed et al, 2008;Gnandi et al, 2009;Abou El Anwar et al, 2020;Galmed et al, 2020;Paat et al, 2021). In general, systematical research on overburden movement and surface deformation in the process of converting open-pit to underground phosphorite mining has not been performed.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation on Stratum and Surface Deformation in Underground Phosphorite Mining Under Different Mining Methods

Wang²,

et al. 2022

Front. Earth Sci.

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With the ending of deep-concave open-pit phosphorite extractions and gradual exhausting of shallow mineral resources, stoping of phosphorite seams has entered or will enter into underground mining. Particularly for excavating slightly inclined thin and medium-thick phosphorite orebodies, roof and surface control under different mining methods is crucial for safe and efficient exploitations. In this study, the study area is located in Kunyang Phosphorite Mine characterized by slightly inclined thin and medium-thick deposits. Based on the occurrence conditions, orebody thickness, dip angle, and more factors, the mining methods of underground phosphorite are selected, including room and pillar mining, cement backfill mining, and caving mining. Numerical analysis on roof deformation and surface subsidence under the three methods is performed. The results show that the amount of roof and surface subsidence decreases successively by the caving method, room and pillar method, and cement backfill method. The maximum roof and surface subsidence by the caving method is 45.7 and 13.3 cm, respectively. Regarding shallow orebodies, the open-pit slope is obviously disturbed by the caving method and room and pillar mining method. Hence, slope displacement monitoring should be emphasized. Compared with the other two methods, the backfill mining method can use mined wastes as backfill materials and has less influence on the roof and surface during stoping and is better at controlling slope stability.

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“…The exploited raw phosphorite is naturally enriched with trace metals (Cd, Cr, Cu, Ni, V, Zn, Ba, Sr, F, U) and rare earths. [18][19][20][21][22][23][24] Phosphorites are transported to the factory of Kp em e beach where they are washed with seawater using sieving and hydrocyclone separation techniques. The resulting large amounts of muddy mine tailings are dumped directly into the sea.…”

Section: Introductionmentioning

confidence: 99%

Polycyclic aromatic hydrocarbons and trace metal contamination of coastal sediment and biota from Togo

Gnandi¹,

Bandowe²,

Deheyn³

et al. 2011

J. Environ. Monit.

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The state of contamination of tropical environments, particularly in Africa, remains a relatively under explored subject. Here, we determined polycyclic aromatic hydrocarbon (PAH) and trace metal concentrations in coastal sediment and biota samples (fish and mussels) from Togo (West Africa). In the sediments, the ∑21 PAH concentrations ranged from <4 ng g(-1) to 257 ng g(-1), averaging 92 ng g(-1). Concentration ratios of low molecular weight PAHs (2-3 rings) versus high molecular weight PAHs (≥4 rings) were always lower than 1 (ranging from 0.08 to 0.46) indicating that high molecular weight PAHs were dominant in all sediment samples, and that PAHs originated mainly from anthropogenic combustion activities. The sediments were also analyzed for major elements and a total of 15 trace metals, which were found in elevated concentrations. The calculated enrichment factor (EF) values relative to the Earth's crust show that the contamination is extremely severe for Cd (EF = 191), severe for Cr (EF = 18) and U (EF = 17.8), moderately severe for Zr (EF = 8.8), for Ni (EF = 6.8), Sr (EF = 5.9) and Ba (EF = 5.4), and moderate for V (EF = 3.6) and Zn (EF = 3.4). Sediments sampled in areas affected by the dumping of phosphorite mine tailings showed particularly high concentrations of trace metals. Overall, concentrations of both PAHs and trace metals in sediment tend to increase from the coastline to the open sea (2 km offshore). This is attributable to the increasingly finer texture of coastal sediment found offshore, which has a terrigenous origin and appears loaded with various contaminants through adsorption processes. Such high loads of trace metals were also found in the biota (fish and mussels). The ratio of measured trace metal concentrations in biota to threshold limits set by the World Health Organization herein defined as relative health factor (RHF) was high. Average RHF values in fish were highest for Se (470), As (250), Ag (97), Ni (78), Mn (63), Fe (53), Pb (36), Cd (10), and Cr (7) while lowest for Cu (0.08) and Zn (0.03). Cd and Al did not bioaccumulate in the analyzed fish species. In mussels, the RHF values were highest for Fe (9,108), As (295), Pb (276), Se (273), Mn (186), Ni (71), Ag (70), Cd (14), and Cu (4).

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Distribution, Speciation, and Extractability of Cadmium in the Sedimentary Phosphorite of Hahotoé-Kpogamé (Southern Togo)

Cited by 10 publications

References 17 publications

Increased Bioavailability of Mercury in the Lagoons of Lomé, Togo: The Possible Role of Dredging

Increased Bioavailability of Mercury in the Lagoons of Lomé, Togo: The Possible Role of Dredging

Numerical Investigation on Stratum and Surface Deformation in Underground Phosphorite Mining Under Different Mining Methods

Polycyclic aromatic hydrocarbons and trace metal contamination of coastal sediment and biota from Togo

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