Distinguishing between soils and sediments

Biological, chemical, and physical processes produce distinctive layers, or horizons, in soils. There are numerous types of soil horizons (Birkeland, 1984). However, the most common from the top of a soil profile to the bottom are the O, A, B, C, and R (Table 3.19). Not all of the horizons are present in every soil. Furthermore, the specific characteristics of each horizon are affected by climate, bedrock composition, the types of vegetation, pH, redox conditions, and time (Faure, 1998), 354-355. 

The O horizon includes leaf litter and other partially undecayed biological matter on the surface (Birkeland, 1984), 7. O horizons are usually thin, especially under oxidizing, warm, and wet conditions, where 

Distillate oil 100-200 pg kg-1 Edward Aul and Associates, Incorporated and E. H. Pechan and Associates (1993) 

Formation water, oil well Alberta, 230 pg kg-1 Smedley and Kinniburgh (2002) 

Formation water Activo Luna 550 pg kg 1 Birkle, Cid Vazquez and Fong 

---