Fifty years after its discharge, methylation of legacy mercury trapped in the Penobscot Estuary sustains high mercury in biota.

Fifty years ago, the Penobscot Estuary was contaminated by mercury discharged from the chlor-alkali plant located in Orrington, Maine, USA. Almost all of the mercury was discharged from the plant during the late 1960s and early 1970s. Despite the much lower mercury discharges in recent decades, present-day concentrations in surface sediment remain high (averaging 350-1100 ng/g dw) and are still high in blood of marsh birds (up to 10.

Regulatory models and the environment: practice, pitfalls, and prospects.

Computational models support environmental regulatory activities by providing the regulator an ability to evaluate available knowledge, assess alternative regulations, and provide a framework to assess compliance. But all models face inherent uncertainties because human and natural systems are always more complex and heterogeneous than can be captured in a model. Here, we provide a summary discussion of the activities, findings, and recommendations of the National Research Council's Committee on Regulatory Environmental Models, a committee funded by the U.