SimpleBox model

Fig. 5 SimpleBox 2.0 model Table 5 Principal characteristics of SimpleBox model (based on [63]) ...

An overview of the principal characteristics of the SimpleBox model is given in Table 5. 

SimpleBox was created as a research tool in environmental risk assessment. Simple-Box (Brandes et al. 1996) is implemented in the regulatory European Union System for the Evaluation of Substances (EUSES) models (Vermeire et al. 1997) that are used for risk assessment of new and existing chemicals. Dedicated SimpleBox 1.0 applications have been used for integrating environmental quality criteria for air, water, and soil in The Netherlands. Spreadsheet versions of SimpleBox 2.0 are used for multi-media chemical fate modeling by scientists at universities and research institutes in various countries. SimpleBox models exposure concentrations in the environmental media. In addition to exposure concentrations, SimpleBox provides output at the level of toxic pressure on ecosystems by calculating potentially affected fractions (PAF) on the basis of species sensitivity distribution (SSD) calculus (see Chapter 4). 

SimpleBox is a nested multimedia environmental fate model in which the environmental compartments are represented by homogeneous boxes. It consists of five spatial scales a regional scale, a continental scale and a global scale consisting of three parts, reflecting arctic, moderate and tropic geographic zones (Fig. 5)... 

Whereas the fugacity approach was used by Mackay for the computation of mass flows and the concentration levels, the SimpleBox adopt the concentration-based piston velocity type mass transfer coefficients (ms-1). This is, mainly, because most scientific papers express the mass transfer in these terms, rather than in terms of the fugacity-based conductivity type coefficients (mol h 1 Pa-1). Furthermore, the transfer and transformation phenomena are treated as simple pseudo first-order processes, similar to Mackay models. 

The multimedia model present in the 2 FUN tool was developed based on an extensive comparison and evaluation of some of the previously discussed multimedia models, such as CalTOX, Simplebox, XtraFOOD, etc. The multimedia model comprises several environmental modules, i.e. air, fresh water, soil/ground water, several crops and animal (cow and milk). It is used to simulate chemical distribution in the environmental modules, taking into account the manifold links between them. The PBPK models were developed to simulate the body burden of toxic chemicals throughout the entire human lifespan, integrating the evolution of the physiology and anatomy from childhood to advanced age. That model is based on a detailed description of the body anatomy and includes a substantial number of tissue compartments to enable detailed analysis of toxicokinetics for diverse chemicals that induce multiple effects in different target tissues. The key input parameters used in both models were given in the form of probability density function (PDF) to allow for the exhaustive probabilistic analysis and sensitivity analysis in terms of simulation outcomes [71]. 

Brandes LJ, den Hollander H, van de Meent D (1996) SimpleBox 2.0 a nested multimedia model for evaluating the environmental fate of chemicals. RIVM report no. 719101029, Bilthoven... 

EUSES. In EUSES 2.0 steady-state exposure concentrations at the regional, continental, and global scales are calculated for all environmental compartments (air, water, soil, sediment, and air) using the multi-media fate model SimpleBox 3.0. 

SimpleBox is a multimedia mass balance model of the so-called Mackay type. It represents the environment as a series of well-mixed boxes of air, water, sediment, soil, and vegetation (compartments). Calculations start with user-specified emission fluxes into the compartments. Intermedia mass transfer fluxes and degradation fluxes are calculated by the model on the basis of user-specified mass transfer coefficients and degradation rate constants. The model performs a simultaneous mass balance calculation for all the compartments, and produces steady-state concentrations in... 

Brandes LH, den Hollander H, van de Meent D. 1996. SimpleBox 2.0 a nested multimedia fate model for evaluating the environmental fate of chemicals. RIVM No. 719101 029. Bilthoven (The Netherlands) National Institute of Public Health and the Environment (RIVM), 156 p. http //www.rivm.nl (accessed December 28, 2007) and HA.den.Hol-lander rivm.nl. 

The BUSES model was developed to support the risk assessment of chemicals under various regulations. BUSES is a spreadsheet-based tool that incorporates SimpleBox, a multimedia fate model, and SimpleTreat, which simulates the distribution and elimination of chemicals in sewage freafment plants. The model estimates the concentrations of a substance in air, water, soil, and sediment at local and regional scales. It simulates the steady-state transport of chemicals between media and scales, and removal of the chemical by degradation and some "disappearance processes" (e.g., leaching to the groundwater, which is not then modeled) [106,107]. 

---