USE OF SRTM AND FIELDWORK IN RURAL VILLAGES NEAR MAOMING, SOUTHERN CHINA, TO ASSESS GROUNDWATER CONTAMINATION FROM OIL SHALE WASTES

Oil shale may become a significant source of crude oil in the future, as the reserves of conventional petroleum begin to wane. The sheer mass of oil shale tailings left over from the kerogen extraction process, however, make waste management a major problem. Water and air pollution, greenhouse gas emissions during processing, waste and land use mismanagement, and destruction of ecological habitats and fauna may occur. Some of these problems are not fully understood and require further study. Groundwater pollution is one of the biggest problems, as illustrated here.

Maoming, southern China, was the site of oil shale mining from 1950 to 1990. Two landfills were created to dispose of 50 million tons of oil shale waste, each about 6-7 km long by 1-2 km wide by 5-6 m high. Percolation of rainfall and surface water into the tailings has lead to aquifer contamination by heavy minerals and organic compounds. Groundwater samples taken at villages near the landfills have been analyzed chemically and exhibit a broad spectrum of pollution levels. The samples showed TDS ranging from 73.3 to 1370 mg/L, a pH range of 2.95 to 6.7, SO4 contents from 34 to 975 mg/L, K contents from 1.75 to 48.95 mg/L, and Mg contents from 0.3 to 77.22 mg/L.

Most water levels for wells sampled near Maoming were 3-6m below the surface during the wet season. Artesian wells were noted during the wet season, suggesting confined aquifers and shallow water tables. Fieldwork and SRTM (Shuttle Radar Topography Mission) data have been used to infer local water table elevations. Seasonal variations, combined with local rises in sea level, make this a particularly promising site for further study, because it is heavily polluted, near the coast, and low enough in elevation to be affected by sea level changes. The rate and lateral extent of the spread of contaminants will change with an increase in sea level, as the mine and shallow aquifers become saturated. The Maoming field site serves as a classic case study regarding the impacts of oil shale mining and waste disposal on groundwater in a region.