The zinc concentration in surficial sediments of Boston Harbor is shown in figure 1, along with locations of known waste inputs. Characteristic Patterns in Contaminant Distributions Contaminants tend to follow distinctive statistical patterns when sufficient numbers of samples are available. The current expanded data set shows patterns similar to those in figure 2. Colors correspond to those in figure 1. In spite of these coherent statistical patterns, the spatial distribution of contaminants shows a high degree of patchiness, as can be inferred from figure 1.
Local variability becomes more extreme in Boston Inner Harbor close to the coasts.
Here, samples 100 meters apart may show markedly different concentration levels, a condition that is partly related to proximity to point sources of contaminants. Estimating Sediment Accumulation Rates on Dredged Bottoms Knowledge of the physical and chemical composition of bottom sediments is needed to guide dredging and sediment disposal for deepening of shipping channels. Thickness of sediments in various locations, Boston Inner Harbor bottom. Such data allow estimation and prediction of sediment supply and burial rates. Accumulation rates help define specific contaminant loading per unit time.