A global Uncertainty and Sensitivity Analysis (UA/SA) of a state of the art food web bioaccumulation model was carried out. We used an efficient screening analysis technique to identify the subset of the most relevant input factors among the whole set of 227 model parameters. A quantitative UA/SA was then applied to this subset, in order to rank the parameters and to partition the model output variance among them, by means of a non-linear regression of the outcomes of one thousand Monte Carlo simulations. The concentrations of four representative persistent organic pollutants (POPs) in two representative species of the coastal marine food-web of the Lagoon of Venice, Italy, were taken as model outputs. The screening analysis showed that the ranking was remarkably different in relation to the species and chemical being considered. The subsequent Monte Carlo based quantitative analysis showed that the relationships among some of the parameters and the model outputs is non linear. The non linear regression showed that the fraction of output variance accounted for by each parameter strongly depends upon the range of the octanol/water partition coefficient (KOW) values which are being considered. In fact, for the low hydrophobic chemicals, the main sources of model uncertainty were the parameters related to the respiratory bioaccumulation, while, for the more hydrophobic chemicals, KOW and other parameters related to the dietary uptake explained the largest fractions of the variance of the organism concentrations of the chemicals. The analysis pointed out that efforts are still needed for reducing uncertainty of model parameters to get reliable results from the application of food web bioaccumulation models.

CIAVATTA Stefano;  LOVATO Tomas;  RATTO Marco;  PASTRES Roberto; 

2009-07-08

SOCIETY ENVIRONMENTAL TOXICOLOGY & CHEMISTRY-SETAC

JRC48743

0730-7268,   

https://publications.jrc.ec.europa.eu/repository/handle/JRC48743,