Metals
193
the southern California coastal waters are 310 metric tons from the atmosphere, 200
tons from sewage, 190 tons from storm runoff, and 40 tons from natural sources
[566]. As lead alkyls are phased out from use in gasolines, it is expected that lead
concentrations in the waters, and in the bivalves, will decrease with time.
Mussel analyses led to the identification of 'hot spots', where the lead concentrations in the mussels, and presumably in their environmental waters, are raised over
adjacent areas as a consequence of fluxes from highly populated industrial areas. The
regional variations may be seen in the data from the US west coast, from its northern
boundary in the state of Washington to its more southerly parts in California
(Fig. 8.5). Low lead concentrations were found in mussels taken in the central California stations, San Mimeon to San Francisco, with the exception of those samples taken
from the Farallon Islands where the levels were high (3.3-9.3 ppm, dry weight). In
contrast, mussels from southern California stations had high lead concentrations,
greater than 2.5 ppm dry weight, with the exception of Point Arguello and Rincon
Cliffs. Levels were especially high at Point La Jolla (6.5-10.0 ppm), Point Fermion
(7.9-8.0 ppm), Santa Catalina (5.2-6.4), and San Pedro Harbour (8.8-17.7). These
high mussel concentrations are attributed to high influxes of lead in the Los Angeles /
San Diego / Santa Barbara region, primarily from automotive exhausts. The lead is
transported principally through the atmosphere, and accommodated in the seawaters
following wet and dry fallout. The subsequent uptake by the mussels is evidenced by
their unusual concentrations.
A similar situation was noted in the mussel lead concentrations on the East coast
(Fig. 8.6). Highest values were found in animals living adjacent to highly populated
areas. For the three year sampling period, elevated levels were observed at Cape
Newagen (4.4-9.5), Portland (4.6-5.3), Cape Ann (8.7-15.6), Boston (5.9-14.2), and
Cape Cod (3.6-6.5). Relative low lead concentrations were observed in mussels from
the northernmost (Blue Hill Falls, Sears Island) and the southernmost (Atlantic City
to Assateague) stations, where concentrations of less than 2 ppm were recorded.
There were no trends in the lead concentrations of oysters collected along the southeast coast of the United States.
Silver. In comparison with lead, the sources of silver in the coastal waters of the US
have not been clearly identified. The photographic industry is, perhaps, the largest
consumer of silver, and its discards probably enter the oceans via sewage. Inputs from
the plating industry to sewage are a secondary source.
There appears to be no significant atmospheric input of silver into the marine
environment. Thus, elevated levels of lead in mussels living adjacent to urban areas
mayor may not be accompanied by complementary increased concentrations of
silver. Such appears to be the case in two west coast stations, the Farallon Islands and
the San Pedro Harbour. Both have high lead concentrations in mussels and low silver
values for the three year sampling period. Neither of these stations receive sewage.
The San Pedro Harbour area does not receive outflow from the Los Angeles river,
which undoubtedly carried anthropogenic lead, washed into it from storm run-off.
In contrast, mussels from stations having exposure to sewage show elevated
amounts of both lead and silver. West coast sample sources include Point La Jolla, San
Diego Harbour, Point Fermin and Santa Catalina Island. Of these four stations, the
193
the southern California coastal waters are 310 metric tons from the atmosphere, 200
tons from sewage, 190 tons from storm runoff, and 40 tons from natural sources
[566]. As lead alkyls are phased out from use in gasolines, it is expected that lead
concentrations in the waters, and in the bivalves, will decrease with time.
Mussel analyses led to the identification of 'hot spots', where the lead concentrations in the mussels, and presumably in their environmental waters, are raised over
adjacent areas as a consequence of fluxes from highly populated industrial areas. The
regional variations may be seen in the data from the US west coast, from its northern
boundary in the state of Washington to its more southerly parts in California
(Fig. 8.5). Low lead concentrations were found in mussels taken in the central California stations, San Mimeon to San Francisco, with the exception of those samples taken
from the Farallon Islands where the levels were high (3.3-9.3 ppm, dry weight). In
contrast, mussels from southern California stations had high lead concentrations,
greater than 2.5 ppm dry weight, with the exception of Point Arguello and Rincon
Cliffs. Levels were especially high at Point La Jolla (6.5-10.0 ppm), Point Fermion
(7.9-8.0 ppm), Santa Catalina (5.2-6.4), and San Pedro Harbour (8.8-17.7). These
high mussel concentrations are attributed to high influxes of lead in the Los Angeles /
San Diego / Santa Barbara region, primarily from automotive exhausts. The lead is
transported principally through the atmosphere, and accommodated in the seawaters
following wet and dry fallout. The subsequent uptake by the mussels is evidenced by
their unusual concentrations.
A similar situation was noted in the mussel lead concentrations on the East coast
(Fig. 8.6). Highest values were found in animals living adjacent to highly populated
areas. For the three year sampling period, elevated levels were observed at Cape
Newagen (4.4-9.5), Portland (4.6-5.3), Cape Ann (8.7-15.6), Boston (5.9-14.2), and
Cape Cod (3.6-6.5). Relative low lead concentrations were observed in mussels from
the northernmost (Blue Hill Falls, Sears Island) and the southernmost (Atlantic City
to Assateague) stations, where concentrations of less than 2 ppm were recorded.
There were no trends in the lead concentrations of oysters collected along the southeast coast of the United States.
Silver. In comparison with lead, the sources of silver in the coastal waters of the US
have not been clearly identified. The photographic industry is, perhaps, the largest
consumer of silver, and its discards probably enter the oceans via sewage. Inputs from
the plating industry to sewage are a secondary source.
There appears to be no significant atmospheric input of silver into the marine
environment. Thus, elevated levels of lead in mussels living adjacent to urban areas
mayor may not be accompanied by complementary increased concentrations of
silver. Such appears to be the case in two west coast stations, the Farallon Islands and
the San Pedro Harbour. Both have high lead concentrations in mussels and low silver
values for the three year sampling period. Neither of these stations receive sewage.
The San Pedro Harbour area does not receive outflow from the Los Angeles river,
which undoubtedly carried anthropogenic lead, washed into it from storm run-off.
In contrast, mussels from stations having exposure to sewage show elevated
amounts of both lead and silver. West coast sample sources include Point La Jolla, San
Diego Harbour, Point Fermin and Santa Catalina Island. Of these four stations, the