Manual of Methods for Soil and Land Evaluation:

One of the primary functions of soil is that of buffering, filtration and transformation of many substances including pollutants. This function is of primary importance when dealing with land evaluation for protecting soil from contamination. Soil protective capacity, or soil attenuation capacity, is the potential of soil to filter polluting agents and to mitigate harmful effects without compromising its functionality. This quality is complex and delicate and can undergo substantial modification even over a brief period. In order for it to be assessed, soil “vulnerability” must be taken into consideration.