Spectrophotometric determination of cyanate and ammonia in water sources around a gold mine

Abstract

Modern mining methods have resulted in an increasing number of hazardous inorganic compounds being discharged into the environment. Although chemical treatments are used for detoxification of these inorganic compounds, they are expensive and not sensitive enough. Speciation products which are hazardous may also be formed. This study focused on the spectrometric determination of cyanide speciation products of cyanate (CNO-) and ammonia (NH3) in water samples from around a Gold Mine environment. The data for the species during sampling months were tested by analysis of variance (ANOVA) and Geometrical Principal Component Analysis. The concentration ranges of speciation products in environmental samples were 0.03 to 53.7 mg/L and 1.70 to 10.0 mg/L for CNO- and NH3 respectively. The obtained values were well above their acute levels. Cyanate and ammonia concentrations decreased with sampling distance along the stream. High levels of CNO- and NH3 concentration up the stream were attributed to conversion of CN- to CNO-, thiocyanate (SCN-) to NH3/CN- to NH3. The decrease downstream may be as a result of the dilution, as the effluent enters the stream.