In coastal waters, particulate metals
constitute a substantial
fraction of the total metals; however, the prevalent water quality
criteria are primarily based on dissolved metals, seemingly neglecting
the contribution of particulate metals. Here we developed a method
to quantify the toxicity risk of particulate metals, and proposed
a way to calculate modifying factors (MFs) for setting site-specific
criteria in turbid waters. Specifically, we used a side-by-side experimental
design to study copper (Cu) bioaccumulation and toxicity in an estuarine
clam, Potamocorbula laevis, under the exposure to
“dissolved only” and “dissolved + particulate” 65Cu. A toxicokinetic-toxicodynamic model (TK-TD) was used
to quantify the processes of Cu uptake, ingestion, assimilation, egestion,
and elimination, and to relate mortality risk to tissue Cu. We find
that particulate Cu contributes 40–67% of the Cu bioaccumulation
when the suspended particulate matter (SPM) ranges from 12 to 229
mg L–1. The Cu-bearing SPM also increases the sensitivity
of organisms to internalized Cu by decreasing the internal threshold
concentration (C
IT) from 141 to 76.8 μg
g–1. MFs were derived based on the TK-TD model to
consider the contribution of particulate Cu (in the studied SPM range)
for increasing Cu bioaccumulation (MF = 1.3–2.2) and toxicity
(MF = 2.3–3.9). Water quality criteria derived from dissolved
metal exposure need to be lowered by dividing by an MF to provide
adequate protection. Overall, the method we developed provides a scientifically
sound framework to manage the risks of metals in turbid waters.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.