Concentration vs. sedimentation

As shown in Table 11.3, the concentrations of trace elements in the water column is - despite anthropogenic pollution - extremely small (10 11 - 10 7 M) illustrating the remarkable efficiency of the continuous "conveyor belt" of the settling adsorbing and scavenging particles. The sedimentary record reflects the accumulation of trace elements in sediments and a profile of concentration vs sediment-depth (or age) gives a "memory record" on the loading in the past (Fig. 11.9). 

---