1.1 MB pdf - Bolsa Chica Lowlands Restoration Project

SECTION 4: RISK CHARACTERIZATION
Nine toxicity bioassays were conducted with sediment collected from the Full Tidal area,
primarily in Cells 1, 3, 8, and 51. The tests were conducted using the marine amphipod
(Eohaustorius estuarius) (Table 3-14). Two tests (from Cell 1 and from between Cell 3 and 8)
resulted in significantly reduced survival and reburial. One test (from Cell 3) resulted in
significant reduction in survival, but not reburial.
Seven sediment bioaccumulation tests were conducted using the clam worm Nereis viriens.
None of the samples were significantly different from controls for survival. However,
bioaccumulation for several chemicals was significantly increased including cobalt, nickel, and
vanadium from worms tested in Cell 3 sediments; and lead in worms tested in Cell 8 sediments.
Semi-Aquatic Birds
Risk estimates for semi-aquatic birds indicated that terns were the most sensitive (Table 4-2).
Chemicals with possible risk (Category B) included cobalt, copper, zinc, and 4,4’-DDE for
terns, and zinc for herons. The NOAEL HQs for these chemicals ranged from 1.9 to 86, and
the LOAEL HQs ranged from 1.5 to 9.6 for copper and zinc, respectively. Chemicals with
some possible risk (Category C) included cobalt (heron) and lead (tern and heron).
Uncertain risks were estimated for several chemicals including barium, chromium,
selenium, and dieldrin. NOAEL HQs for these chemicals ranged from 1.0 for barium to
57 for chromium, both for terns.
4.1.2.3 Future Full Tidal
Aquatic Plants
Estimates of potential risk to aquatic plants in sediments of the Future Full Tidal area
indicated that risks are primarily a result of metals and PAHs. A summary of HQs
exceeding one for aquatic plants is presented in Table 4-1. Two chemicals, nickel and
selenium, exceeded chronic NOECs with HQs of 650 and 384, respectively. Comparisons to
chronic LOECs resulted in 17 inorganics and 4 organics posing a possible risk (Category B).
The HQs ranged from 1.9 for 4-nitrophenol to 850 for lead. Of those chemicals exceeding
chronic LOECs, 4 were evaluated using an exposure point concentration that was ½ the
reporting limit for a non-detect.
Aquatic Invertebrates
There were 14 inorganic and 28 organic chemicals with probable risk (Category A)
(Table 4-3). Chemicals that exceeded both the ER-M and LC 50 consisted of chromium, nickel,
zinc, chrysene, fluorene, phenanthrene, and low MW PAHs. Several chemicals had HQ
exceeding 100 for either the ER-M or the LC 50 . Chemicals with HQs greater than 100 from
comparisons to the ER-M included mercury (268) and chlordane – technical (633). Chemicals
with HQs greater than 100 for comparisons to the LC 50 included beryllium (133), cobalt
(181), nickel (224), thallium (276), and vanadium (193).
Chemicals with possible risk (Category B – exceedance of a chronic low-effect level, but not
an acute effect level) included anthracene, benzo(a)anthracene, benzo(a)pyrene,
benzo(b)fluoranthene, fluoranthene, pyrene, and high MW PAHs. The HQs for all these
chemicals were less than 10.
There were no chemicals in Category C (some possible risk), but there were several with
uncertain risk (Category U). These chemicals exceeded the NOEC, but did not have a loweffect
level RTV available. The NOEC HQs for these chemicals ranged from 44 to 1273.
SAC/143368(004.DOC) 4-9 ERA REPORT
7/31/02