The purpose of this study was to characterize the soils subject to gold mining. Data collection consisted of sampling soil from the 0-20 cm layer, in corn fields, under natural vegetation and in gold panning sites (gold-bearing soil and washed gold-bearing soil). A total of 48 composite samples of 1 kg of soil were analyzed at the ITRA Soil Laboratory in Lomé. The results of physicochemical analysis show that the washed gold soils have low contents of organic matter, carbon, nitrogen, calcium and sodium; and are sandy in texture. Washed gold soils have a very low level of fertility. Over the entire study area, the levels of trace metal elements range from 0.01 to 10.24 mg/kg for copper, 0.02 to 4.01 mg/kg for zinc, 0.01 at 5.05 mg/kg for lead and 0 to 1.40 mg/kg for cadmium. The pollution index varies from 0.01 to 0.09 depending on the localities and is less than 1 in all localities. The lowest index is obtained at Kéméni and Kpaza sites, indicating a low accumulation of trace elements on these sites. The sites of its localities are not polluted by the Cu, Zn, Pb, and Cd studied. Gold panning in the Central Region of Togo leads to soil degradation.

Zio River catchment drains many cities that it receives waste, domestic and industrial effluents and its waters used to supply drinking water from downstream to upstream. Some schools use it in school canteens without treatment. Meanwhile, no study on tools of water resources management is done in this basin and whole of Togo. To fill this gap, the environmental variables and benthic macroinvertebrates assemblages were investigated to assess ecological integrity of the Zio River and its tributaries that varied in disturbance from upstream to downstream. Macroinvertebrates were sampled during four campaigns from 42 sites selected to correspond with different human activities in the catchment. The AFNOR methods were used for physicochemical analysis. Multivariate analyses (PCA) were applied to characterize sites typology and FCA for similarity between sites or taxa. The result showed that physicochemical variables of downstream sites, with the lower level of dissolved oxygen (0.6mgO2/L) and high contents of ion NH4 (5.6mg/L), KMn (30.7mgO2/L) and high Conductivity (10670