1.1 MB pdf - Bolsa Chica Lowlands Restoration Project

SECTION 4: RISK CHARACTERIZATION
Terrestrial Invertebrates
Terrestrial invertebrates were quantitatively evaluated through comparison to RTVs from
literature sources as site-specific toxicity values were not derived (Table 3-26). Similar to
plants, most RTVs available were for chronic LOECs and only a few chronic NOECs were
used. Risk estimates for terrestrial invertebrates (Table 4-1) indicated that cadmium (HQ=19)
and zinc (HQ=116) exceeded chronic NOECs. Chronic LOECs were exceeded by 11 inorganic
and 7 organic chemicals indicating a possible risk (Category B) for these COECs. The HQs
ranged from 1 to 565; vanadium (HQ=565), mercury (HQ=380), and chromium (HQ=313)
had the highest HQs. Of those chemicals exceeding chronic LOECs, 2 were evaluated using
an exposure point concentration that was ½ the reporting limit for a non-detect.
Upland Birds
Birds were evaluated quantitatively through comparison of estimated total daily dosages to
chronic NOAEL and LOAEL RTVs obtained from the literature (Table 3-27). Site-specific
toxicity values and acute toxicity values were not obtained for birds. Two upland bird
species were used for screening at the Future Full Tidal including sparrow and kestrel
(Table 4-2). Sparrows were more sensitive to chemical concentrations (i.e., had a higher HQ)
than kestrels. Six metals exceeded NOAELs and two, lead and zinc, also exceeded LOAELs.
LOAELs were not available for barium, chromium and vanadium so resulting risk to these
chemicals is uncertain (Category U). Some possible risk (Category C) is posed by cobalt for
both receptors and lead and zinc for kestrels because the LOAEL was not exceeded. Lead
and zinc pose a possible risk (Category B) to sparrows because both the NOAEL and
LOAEL were exceeded. NOAEL-based HQs ranged from 1.1 for barium (sparrow) to 13 for
lead (sparrow). LOAEL-based HQs for sparrows were 1.4 for lead and 1.01 for zinc.
Mammals
Mammals were quantitatively evaluated in a similar manner as birds, with the harvest
mouse and the coyote as representative species of mammals using the Future Full Tidal area
(Table 4-2). Inorganics were the only COECs for these receptors. The potential risk was
uncertain (Category U) for cobalt and vanadium because LOAELs were not available. There
is some possible risk (Category C) from exposure to barium and lead because the LOAELs
were not exceeded. The highest NOAEL HQ was 69 for barium (mouse).
4.1.1.2 Gas Plant Pond Area
Terrestrial Plants
COPECs detected in the Gas Plant Pond Area that exceeded available chronic NOECs for
terrestrial plants consisted of selenium and nickel with HQs of 11 and 1.7, respectively
(Table 4-1). Chronic LOECs were exceeded by 11 chemicals indicating a possible risk
(Category B). Of these chemicals, arsenic (HQ=41), benzo(g,h,i) perylene (HQ=23), and
benzo(a)pyrene (HQ=21) had the highest HQs. Of those chemicals exceeding chronic
LOECs, 5 were evaluated using an exposure point concentration that was ½ the reporting
limit for a non-detect.
Terrestrial Invertebrates
Available chronic NOECs for terrestrial invertebrates were not exceeded, but arsenic, chromium,
copper, vanadium, and acenaphthene all exceeded chronic LOECs indicating a possible risk to
terrestrial invertebrates from these COECs. HQs ranged from 1.1 to 3.8 (Table 4-1).
ERA REPORT 4-4 SAC/143368(004.DOC)
7/31/02