A laboratory study of the leachate composition of selected metals in cemeteries (South Africa)

Abstract

Considerable research has been conducted on the physical and chemical corrosion of metals under various environmental conditions, but less attention has been given to the impact of corrosion on the environment. One such potentially hazardous situation may occur in cemeteries where metals and coatings used in the manufacturing of coffins may corrode, seep into the soils, and could end up in nearby water sources. The aim of this project was to determine whether burial materials corrode and leach into groundwater under controlled laboratory conditions. This was achieved by burying samples of burial materials in containers with three different soil types, namely sand, silt and clay. The experimental containers were exposed to various conditions simulating typical South African temperatures, rainfall intensities and with different pH values. A total of 24 simulations and 3 controls were tested. The leachates of each sample were collected every 8 weeks over a period of 6 months and tested for aluminium, iron, copper and zinc. In this experiment, it becomes evident that coffin materials do corrode and become mobile; however, they react differently in different soil media and under diverse environmental conditions. In general, the most corrosive conditions are high temperatures and acidic rainfall. Zn is the most corroded and mobile metal, with Fe being the least. It is notable that Al, Fe and Cu continue to leach out of the soils even after a period of 6 months. This may pose a health and environmental problem and a programme of groundwater quality monitoring should be undertaken in the vicinity of cemeteries.