Distribution of Fluoride in the Phosphorite Mining Area of Hahotoe–Kpogame (Togo)

Abstract

Background. Phosphorites in the mining area of Hahotoé-Kpogamé contain high levels of fluoride that can cause illness among people living close to the mining and processing sites. Objectives. To assess the distribution of fluoride in the different areas around the phosphorite mining areas in Togo. Methods. Analyses were performed by molecular absorption spectrometer (HACH DR3800) according to the procedure manual at the geochemical laboratory of the University of Lomé. The sodium 2-(parasulfophenylazo)-1,8-dihydroxy-3,6-naphthalenedisulfonate (SPADNS) method was used to determine fluoride contents and the PhosVer® 3 with acid persulfate digestion method was used to measure phosphorus pentoxide (P 2 O 5). GraphPad Prism version 3.0 software was used for the data processing. Results. The surface water of the mining sites had a fluoride content ranging from 0.38 to 3.52 mg/l (average = 1.33 mg/l; n = 10, n is the number of samples). Groundwater in this area had a fluoride content between 0.15 mg/l and 1.39 mg/l (average = 0.58 mg/l, n = 15). In the groundwater in the villages around the phosphorite processing plant, the fluoride content ranged between 0.15 and 0.63 mg/l (average = 0.41 mg/l; n = 22). The fluoride content in the water of the phosphorite mining area was higher than in Gbodjomé (reference area). Meanwhile, assessment of the effluents discharged into the ocean had a fluoride content ranging from 12 to 20 mg/l. In dusts, the P 2 O 5 and fluoride contents were 36.02% and 1.85%, respectively. Vegetables from the local market garden produce showed levels of fluoride up to 2.06%. The average contents of P 2 O 5 and fluoride in one of the phosphorite profiles were 32.38% and 3.00%, respectively. A significant correlation was observed between P 2 O 5 and fluoride. Conclusions. The correlation between P 2 O 5 and fluoride in phosphorites shows that phosphorite mining is the main source of fluoride pollution in this area.

Assessment of Groundwater Quality in Areas Surrounding Thundulu Phosphate Mine, Phalombe District, Malawi

“…The high fluoride content may be linked to the basic pH observed during the dry season. A basic pH with moderate conductivity favours fluoride dissolution in water (Tanouayi et al 2016). It is also worth noting that interaction between water and rocks is one of causes of fluoride in groundwater, and apatite is one of the main ore minerals for phosphate.…”

Fluorine in the environment, a review of its sources and geochemistry

“…It is apparent that F contamination can also occur as a result of extraction of phosphate rock. Tanouayi et al (2016) report that dental fluorosis is endemic in the phosphorite mining region of Hahotoe-Kpogame, Togo. The authors concluded that Fpollution of waters, soils and vegetables grown in the region, as a result of the mining, is responsible for the fluorosis problems.…”

Changes in liquid and atmospheric inputs to the marine environment from land (including through groundwater), ships and offshore installations

“…For example, in Togo, severe sediment, water and biota impact from metals has been documented, although other mining regions likely exhibit similar impacts. The phosphorite deposits of Togo, extracted since 1960 in the phosphate mines at Hahatoé and Kpogamé in southern Togo, are naturally enriched with metals and rare earth elements (Tanouayi and others, 2016). The ore processing allows the separation of the phosphorus-rich industrial fraction, leading to concentrations greater than 1 mm in seawater once phosphorite tailings are dumped into the ocean.…”