Environmental Pollution Caused by Laboratory Gold Processing: A Study of Soil and Water Contamination by Heavy Metals

Abstract

Waste generated during gold ore processing often contains toxic substances such as heavy metals like lead and chemicals (cyanide, acids). If not properly controlled, these components can contaminate/pollute soil and ecosystems. The objective of this study is to assess the degree of soil and groundwater contamination around a mining laboratory where chemical and metallurgical analyses are carried out. The main sources of contamination identified come from lead smelting (“Fire Assay”) and aqua regia digestion activities, which generate solid waste and liquid effluents rich in heavy metals and acidic substances. To carry out this assessment, soil, wastewater, and groundwater samples were collected inside the laboratory. The samples were analyzed to determine the presence of heavy metals such as lead, as well as physical and chemical parameters such as pH and conductivity. The results of the physical and chemical parameters of wastewater from basins A and B indicate high acidity ranging from 1.87 to 2.57, an average temperature of 26 °C, and high mineralization due to high electrical conductivities exceeding 2000 μS/cm. RFX analysis shows a high presence of heavy metals, lead (3435.49 ppm), chromium (439.21 ppm), arsenic (155.59 ppm), and strontium (1066.13 ppm), illustrating significant soil contamination, particularly in areas where solid residues (cups, crucibles, slag) are stored in the open air. Chemical analysis of groundwater reveals that it is of good quality and meets WHO standards. This study highlights the environmental impact of current waste management practices in laboratories and emphasizes the urgent need to implement pollutant treatment solutions to limit the spread of contaminants in the environment.