Dj. Hansen et al., PREDICTING THE TOXICITY OF METAL-CONTAMINATED FIELD SEDIMENTS USING INTERSTITIAL CONCENTRATION OF METALS AND ACID-VOLATILE SULFIDE NORMALIZATIONS, Environmental toxicology and chemistry, 15(12), 1996, pp. 2080-2094
We investigated the utility of interstitial water concentrations of me
tals and simultaneously extracted metal/acid-volatile sulfide (SEM/AVS
) ratios to explain the biological availability of sediment-associated
divalent metals to benthic organisms exposed in the laboratory to sed
iments from five saltwater and four freshwater locations in the United
States, Canada, and China. The amphipod Ampelisca abdita or the polyc
haete Neanthes arenaceodentata were exposed to 70 sediments from the f
ive saltwater locations, and the amphipod Hyalella azteca or the oligo
chaete Lumbriculus variegatus were exposed to 55 sediments from four f
reshwater locations in 10-d lethality tests. Sediment toxicity was nor
related to dry weight metals concentrations. Almost complete absence
of toxicity in spiked sediments and field sediments where metals were
the only known source of contamination and where interstitial water to
xic units (IWTUs) were <0.5 indicates that toxicity associated with se
diments having SEM/AVS ratios <1.0 from two saltwater locations in ind
ustrial harbors was not metals-related as these sediments contained <0
.5 IWTU. Metals-associated toxicity was absent in 100% of sediments fr
om the remaining three saltwater field locations, where metals were th
e only known source of contamination and SEM/AVS ratios were less than
or equal to 1.0. Two-thirds of 45 sediments from seven saltwater and
freshwater field locations having both IWTUs >0.5 and SEM/AVS ratios >
1.0 were toxic. Toxicity was observed less often when SEM/AVS ratios >
1.0 (39%) or IWTUs >0.5 (55%) were used alone. The difference between
the molar concentrations of SEM and AVS (SEM AVS) can provide importan
t insight into the extent of additional available binding capacity, Th
e magnitude by which AVS binding has been exceeded, and, when organism
response is considered, the potential magnitude of importance of othe
r metal binding phases. For these reasons, SEM - AVS should be used in
stead of SEM/AVS ratios as a measure of metals availability. Over all
published experiments with both metal-spiked and field sediments, SEM
- AVS and IWTUs accurately (99.2%) identified absence of sediment toxi
city and with less accuracy (79.1%) identified the presence of toxicit
y.