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Modeling of Engineered Nanoparticles with
SimpleBox4nano: Model Definition and Evaluation
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Abstract
Screening level models for environmental
assessment of engineered
nanoparticles (ENP) are not generally available. Here, we present
SimpleBox4Nano (SB4N) as the first model of this type, assess its
validity, and evaluate it by comparisons with a known material flow
model. SB4N expresses ENP transport and concentrations in and across
air, rain, surface waters, soil, and sediment, accounting for nanospecific
processes such as aggregation, attachment, and dissolution. The model
solves simultaneous mass balance equations (MBE) using simple matrix
algebra. The MBEs link all concentrations and transfer processes using
first-order rate constants for all processes known to be relevant
for ENPs. The first-order rate constants are obtained from the literature.
The output of SB4N is mass concentrations of ENPs as free dispersive
species, heteroaggregates with natural colloids, and larger natural
particles in each compartment in time and at steady state. Known scenario
studies for Switzerland were used to demonstrate the impact of the
transport processes included in SB4N on the prediction of environmental
concentrations. We argue that SB4N-predicted environmental concentrations
are useful as background concentrations in environmental risk assessment