TITLE:
Silver Nanoparticle Adsorption to Soil and Water Treatment Residuals and Impact on Zebrafish in a Lab-scale Constructed Wetland
AUTHORS:
Angela Ebeling, Victoria Hartmann, Aubrey Rockman, Andrew Armstrong, Robert Balza, Jarrod Erbe, Daniel Ebeling
KEYWORDS:
Silver Nanoparticles; Soil; Water Treatment Residuals; Constructed Wetland; Zebrafish; Remediation
JOURNAL NAME:
Computational Water, Energy, and Environmental Engineering,
Vol.2 No.3B,
October
24,
2013
ABSTRACT: Nanoparticles ( 100 nm) are
becoming more prevalent in residential and industrial uses and may enter the
environment through wastewater. Although lab studies have shown that
nanoparticles can be toxic to various organisms, limited research has been done
on the effects of nanoparticles in the environment. Environmental conditions
such as pH and ionic strength are known to alter the biotoxicity of
nanoparticles, but these effects are not well understood. The objectives of
this research were to determine the impacts of silver nanoparticles (AgNP) on
zebrafish in the pseudo-natural environment of a lab-scale constructed wetland,
and to investigate wastewater remediation through soil and water treatment
residual (WTR) adsorption of AgNPs. Concurrently, the effect of particle size on
AgNP sorption was examined. Researchers exposed adult zebrafish in a lab-scale
constructed wetland to concentrations of AgNP ranging from 0 - 50 mg
AgNP/L and compared them to negative controls with no silver exposure and to
positive controls with exposure to silver nitrate. The results suggest that
aggregated AgNP do not impact zebrafish. Separately, sorption experiments were
carried out examining three media - a wetland soil, a silt loam soil, and a WTR
- in their capacity to remove AgNPs from water. The silt loam retained less
AgNPs from solution than did the wetland soil or the WTR. In the WTR AgNPs were
associated with sand size particles (2 mm - 0.05 mm),
but in the wetland soil and silt loam, approximately half of the AgNPs were
associated with the sand-sized particles, while the rest were associated with
silt sized (~0.05 mm) or smaller
particles. The larger sorption capacity of the wetland soil and WTR was
attributed to their higher carbon content. The sorption data indicate that
AgNPs adsorbed to soil and WTRs and support the idea that natural and
constructed wetlands can remove AgNPs from wastewater.