STATUS OF THE HABITAT: CHEMICAL CONSIDERATIONS 
Metals and Nutrients 
by 
Dr. Gordon T. Wallace 
Environmental Sciences Program 
University of Massachusetts at Boston 
Harbor Campus 
Boston, MA 
Metal contamination of coastal marine environments has been linked to human 
health problems in areas where massive contamination has occurred (Kurland et al., 1960). 
However, the effects of chronic metal contamination on a lesser scale have been ill- 
defined, either from a human health or coastal ecosystem perspective. Human health 
concerns associated with the consumption of mercury-contaminated seafood have 
generally raised the level of public concern regarding ingestion of seafood potentially 
contaminated by toxic materials introduced into marine and fresh waters. However, 
sublethal threats to the ecosystem have received less attention, perhaps because of the 
uncertainty surrounding attempts to quantify such effects. We cannot, for example, 
definitively answer questions concerning the relative magnitudes of the effect of pollution 
and overfishing on valuable fisheries resources. Our ignorance of potential low-level 
effects of pollutants in coastal marine environments is coupled with increasing pressure to 
use these same coastal environments to receive large quantities of wastes. The Boston 
Harbor and adjacent Massachusetts Bay coastal environment is perhaps one of the most 
significant examples of this situation where ignorance coupled with inappropriate disposal 
practices has left us with a legacy of long-term contamination and uncertainty about the 
resultant effects on the ecosystem. 
One aspect of this contamination includes the introduction of metals, some of which 
are known to be toxic, to the Boston Harbor/Massachusetts Bay ecosystem. The 
predominant sources of metals to Boston Harbor are shown in Figure 1. Effluent from 
primary wastewater treatment enters the Harbor at the Deer Island, Nut Island, and Hull 
outfalls. Metals and other contaminants are also introduced into the Harbor from the 
combined sewer overflows prncipally located in the Inner Harbor and Dorchester Bay. 
Boston Harbor can be classified, using the definition of Fairbridge (1980), as a 
marine estuary. Freshwater input is minimal. The relative magnitude of sewage and 
riverine inputs into the Harbor : s given in Table 1. The rivers account for approximately 
one-third of the freshwater input. The bulk of the remaining freshwater input is primary 
effluent from the two sewage treatment plants with smaller amounts coming from the 
combined sewer overflows (CSOs). Dry weather inputs are the primary source of 
pollutants to the Harbor from CSOs rather than those from wet weather flows. 
