Mercury speciation and effects on soil microbial activities

To study Hg toxicity on soil microbes and their activities, it is necessary to understand its various forms in soils. The objectives of this study were to investigate Hg speciation in four soil types spiked with Hg (300 mg kg−1 soil) and its effects on soil microbial respiration and enzymes (amidohydrolases and phosphatase) activities. An assessment of the chemical forms, amounts, reactions, and mobility of Hg in soils and sediments is of significant importance to improve and maintain soil and environmental health and sustainability. Mercury speciation analysis was investigated under acidic and alkaline conditions using a modified sequential procedure, which differentiates Hg into the four distinct fractions. Soil microbial respiration and enzymes activities were determined under laboratory settings, by incubating the soils at 25°C for 30 days, and then determining the amount of CO2 evolved. Speciation results revealed that the water soluble form was the least, with < 1% of the total Hg in the soil types ...