Particulate pollution of karst groundwaters from marble quarrying, Alpi Apuane, Italy

The marble of the Alpi Apuane, northern Italy, is perhaps the world's most famous ornamental stone, However, scanning electron microscopy of suspended sediments at Cartaro Springs, near Massa, confirms the quarries as major sources of particulate groundwater pollution. Turbidity, conductivity, discharge and total suspended sediment data shows that at least 340 t of suspended sediment passed through the spring system in the twelve months to May 2000. However, due to off-the-scale discharge and turbidity observations, this figure may easily exceed 1000 t. At least 80 t of sediment may be discharged during single storm events, with total suspended sediment concentrations exceeding 12,500 mg L-1, possibly the highest levels ever recorded in karst spring waters. With a recharge area unlikely to exceed 10 km2, the annual sediment yield may be as high as 100 tonnes km-2, making it comparable with many highly turbid surface river systems. As cutting and removal of a typical marble block generates -0.76 t of sand-grade sediment, and with thousands of blocks removed annually, there is no shortage of sediment supply to the karst system.