This study is a contribution to establishment a geochemical soil database around gold-bearing zones. The main objective is to evaluate the total current levels of heavy metals such as arsenic (As), cadmium (Cd), barium (Ba), vanadium (V), nickel (Ni), copper (Cu), iron (Fe), mercury (Hg), manganese (Mn), zinc (Zn), titanium (Ti), strontium (Sr) and lead (Pb) in soils around Gbétogo gold zone located at Seguela in Côte d'Ivoire. To achieve this, 5 soil pits were opened, described and sampled. A total of 19 samples from the 5 pits were collected and 10 other composites were taken from the surface horizons (0-20 cm) near the mine site. Heavy metals concentrations (As, Cd, Co, Cr, Cu, Ni, Pb and Zn) in soils were determined by X-ray fluorescence (XRF) and the hydrogen potential. The results indicate that the soils are acidic and essentially Cambisol-type. Some heavy metals such as Ni (21.8 to 128.05 mg.kg-1), Cu (27.17 to 96.31 mg.kg-1), Mn (226.57 to 3251.82 mg.kg-1), V (323.28 to 509.18 mg.kg-1), Ba (153.20 to 566.94 mg.kg-1) and Ti (4149.67 to 39823.88 mg. kg-1) have concentrations above the recommended standards representing a natural geochemical anomaly, while As, Cd, Zn, Sr and Pb have lower concentrations. Soils have mercury (Hg) contamination ranging from 1.94 to 15.95 mg.kg-1. The ranking, in descending order from highest to lowest concentrations, is as follows: Fe > Ti > Mn > V > Ba > Ni > Cu > Zn > Sr > Pb > Hg > As > Cd.

This study was conducted to estimate the water requirement of the plant Lippia multiflora MOLDENKE. (Verbenaceae), also known as the bush tea or Gambia tea. Seeds initially germinated, are transplanted into pots of 14.5 cm high and 8.5 cm in diameter, completed soil indoors. The treatment consists of 5 parts water, I1, I2, I3, I4 and I5, respectively, for 15, 30, 50, 70 and 100 per cent of the usable reservation made by spraying the plants, for 3 months. Weighing pots with plants were made before and after watering, to calculate actual evapotranspiration (ETa).
The results show that actual evapotranspiration of Lippia multiflora, nursery ranges from 0.5 mm.d-1 to 2 mm.d-1. Plants with the irrigation dose, received I1, have a low ETR for the 3 months, followed by I2. Irrigation doses I3, I4 and I5 indicate ETR ranging from 1 mm to 2 mm per day. The crop coefficient in nursery phase is 0.32 for the month of May and 0.23 in July.
Regarding the vegetative growth, the results obtained show that, it is the I3 or I4 irrigation doses which allow a homogeneous development of the plants. These doses are thus, considered the maximum evapotranspiration of Lippia multiflora. And Culture of Lippia multiflora, it is necessary to go through the nursery phase by providing 50 or 70 per cent usable reserves of soil for optimal growth.