Sediment and Water Quality
The Stellwagen
Bank Sanctuary, because of its proximity to the large population of
the coastal zone in Massachusetts, New Hampshire and southern Maine
as well as being "downwind" from the industrial activity of
the Midwest and northeastern part of the U.S., is subject to the introduction
of chemicals of environmental concern from a variety of anthropogenic
sources. These include direct discharge of waste to coastal waters (generally
referred to as point sources), and runoff and atmospheric deposition
(generally referred to as non-point sources). In combination these sources
have resulted in elevated sediment and water column concentrations of
a variety of inorganic and organic "chemicals of environmental
concern" on a global scale. (The term "chemical of environmental
concern" is defined herein as those chemicals that have the potential
to exert deleterious effects on ecosystem and human health.) Coastal
habitats, such as that represented by Stellwagen Bank in Massachusetts
and Cape Cod Bays, frequently bear the brunt of such inputs because
of their proximity to the sources and the enhanced biogeochemical processes
(biological activity and higher rates of particle scavenging, see below)
that tend to sequester contaminants in the nearshore zone. This section
attempts to provide an overview the available data on contaminant sources
and the resultant distributions and concentrations in the sediment and
water column in the vicinity of Stellwagen Bank. The potential effects
of these contaminants are the subject of a separate section of this
document (see Section II.C.).
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