Since that influent data was collected, a number of communities have voluntarily initiated pollution minimization programs. Due to its behavior, an extremely high percentage of mercury contained in wastewater becomes concentrated in treatment plant bio-solids or sludge. Thus, bio-solids concentration data are good predictors of what plants have elevated mercury loadings. As detection limits have decreased, we have discovered just how prevalent mercury is in the environment. We have even found mercury in some of the most pristine lakes in the state.
Researchers attribute it to atmospheric deposition.
In other words, mercury is not only in our lakes and rivers, but also in the air. This complicates the task of obtaining reliable sample results. Although laboratories are concerned with controlling sources of mercury contamination, experience has taught us that perhaps a bigger problem in obtaining reliable low-level mercury data is controlling contamination during sampling. The efforts necessary to control contamination increase significantly as detection limits decrease. Equipment exhaust and dust can also be contributors.