3.3.2 Sediment Contaminants: Metals and Organics 
Effects Range-Low (ERL) and Effects Range-Median (ERM) sediment 
quality guideline (SQGs) values from Long et al. (1995) were used to help in 
interpreting the biological significance of observed chemical contaminant levels in 
sediments. ERL values are lower-threshold bioeffect limits, below which adverse 
effects of the contaminants on sediment-dwelling organisms are not expected to 
occur. In contrast, ERM values represent mid-range concentrations of chemicals 
above which adverse effects are more likely to occur. A list of 28 chemicals, or 
chemical groups, for which ERL and ERM guidelines have been developed is 
provided in Table 3.3.2 along with the corresponding SQG values (from Long et 
al. 1995). Nickel was excluded from the present assessment because the SQG 
values have a low reliability for West Coast conditions, where naturally high 
crustal concentrations of the metal exist (Long et al. 1995, Long et al. 2000). 
Lauenstein et al. (2000) also found historical background concentrations of nickel 
in sediment cores along the West Coast in a range of 35-70 pg/g, which bracket 
the nickel ERM value of 51.6 pg/g. Any site with one or more chemicals (other 
than nickel) that exceeded corresponding ERM values was rated as having poor 
sediment quality, any site with five or more chemicals between corresponding 
ERL and ERM values was rated as fair, and any site that had less than five ERLs 
exceeded and no ERMs exceeded was rated as good (sensu U.S. EPA 2004). 
Sediments throughout the shelf survey area were relatively 
uncontaminated except for a group of stations in the SCB. Overall, about 99% of 
the total survey area (represented by 230 stations) had a rating of good, < 1% 
(represented by seven stations) had fair conditions with > 5 chemicals in excess 
of ERL values, and < 1% (represented by 22 stations) had poor conditions with > 
1 chemical in excess of the higher-threshold ERM values (Fig. 3.3.5). The 
pesticides 4,4'-DDE and total DDT were the only two contaminants that 
exceeded corresponding ERM values (Tables 3.3.3, 3.3.4). The ERM for total 
DDT was exceeded at 17 stations (representing < 1% of the overall survey area) 
and the ERM for 4,4'-DDE was exceeded at 22 stations (representing < 1% of 
the overall survey area). All of these sites were in California near Los Angeles. 
Total DDT and 4,4'-DDE were found in excess of the lower-threshold ERL values 
at 41 and 31 stations respectively, all of which again were in California, mostly in 
the Los Angeles area (Tables 3.3.3, 3.3.4; Figs. 3.3.6, 3.3.7). 
Ten other contaminants, including seven metals (As, Cd, Cr, Cu, Hg, Ag, 
Zn), 2-methylnaphthalene, low molecular weight PAHs, and total PCBs were 
found at moderate concentrations in excess of corresponding, lower-threshold 
ERL values (Tables 3.3.3, 3.3.4). The most prevalent in terms of area were 
chromium (31%), arsenic (8%), 2-methylnaphthalene (6%), cadmium (5%), and 
mercury (4%). The 2-methylnaphthalene and mercury exceedances were limited 
entirely to California. The mercury exceedances were all at non-sanctuary sites 
in California, particularly in the Los Angeles area (Fig. 3.3.8), while the 2- 
methylnaphthalene exceedances were conspicuously grouped around the 
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