CONTAMINATION FOR MERCURY IN THE SMALL MINING

OF THE REGION DE ATACAMA, CHILE

E. Pesenti, E. Fernández, W. Silva

University of Atacama, Avenue Copayapu 485, Copiapó, Chile.

mailto:epesenti@gea.idictec.uda.cl epesenti@gea.idictec.uda.cl

The mercury is considered as one of the most dangerous metallic pollutants for the environment, this due to its step to vapor and its easiness to form compound organic.

In the Region of Atacama, the small mining of the gold (pirquineros) uses to the mercury in their extraction process to be easy to apply and of consenting in the trade.

The results of an environmental sampling developed in different “Trapiches” of Copiapó City are presented whose main objective consisted basically on characterizing for Hg the residual discharges of the plants, analysis of concentrated and tailings. It was also measured their environmental impact by means of analysis of soils, sampling of atmospheric mercury and analysis of biological samples, mainly workers' urines and vegetables watered with clear waters of their tailings.

The samples of liquid residuals were gathered manually by means of a plastic recipient and were preserved to pH 2 for analysis of Hg.

The solid matter was obtained manually with a tablespoon of stainless steel and was deposited in polyethylene containers for its later analysis.

The concentration of vapor of mercury was determined with an analyzer of mercury Hg 2000 (spectrophotometry of atomic absorption).

The levels of mercury in urine and vegetables were determined by hidrure generation.

The obtained results show concentrations that vary between 0,0002 and 0,0084 mg/l of Hg in the residual waters.

The concentrate show tenors that vary between 1156 and 2170 mg/kg, the tailings between 65 and 105 mg/kg and the concentration in the impacted soils vary between 2,7 and 12,4 mg/kg.

In what concerns to the concentrations of vapor of mercury vary according to the area, being critical values in the area of the “estruje” and “quema” of the pellet between 320 and 400 ug/m3.

The biological monitoreo showed values between 11 and 1390 ug/l of mercury in urines. The values of mercury in vegetables vary among 0,237 mg/kg for alcayota (cucurbita ficifolia) and 0,311 mg/kg for tomatoes (lycopersicon esculentun).

The results show an important contamination of mercury in the small mining of the gold. The chilean norm for labor atmospheres for vapor of mercury (40 ug/m3) it is surpassed easily and also the concentration of mercury in some workers' urine (50 ug/l).