Climate Variability and Change—Hydrological Impacts (Proceedings of the Fifth FRIEND World
Conference held at Havana, Cuba, November 2006), IAHS Publ. 308, 2006, 586–590.
A global assessment of chemical effluent dilution capacities
from a macro-scale hydrological model
VIRGINIE D. J. KELLER1, MICK J. WHELAN2 & H.
GWYN REES1
1 Centre for Ecology and Hydrology, Wallingford, Oxfordshire OX10 8BB, UK
vke@ceh.ac.uk
2 Safety and Environmental Assurance Centre, Unilever Colworth, Colworth Park, Bedfordshire MK44 1LQ, UK
Abstract
Environmental risk
assessments for “down-the-drain” chemicals (e.g. pharmaceuticals and household
product ingredients) are generally based on a comparison between predicted
environmental concentration (PEC) and predicted no effect concentrations
(PNEC) for a generic environment with a fixed dilution factor. For PEC
calculations spatial and temporal variability is often not explicitly taken
into account. In the absence of detailed local-scale information for specific
point-sources, spatially-explicit approximations can be made, based on the
ratio of available surface water and domestic water consumption. In this paper,
a new methodology is proposed for predicting surface water dilution at a global
scale. The approach employs 0.5° resolution geographical data on national
boundaries, population density, runoff (from
water balance model calculations) and domestic water consumption to
produce dilution factor maps for the global land surface. The proposed methodology has great
potential for improving screening-level chemical risk assessments.
Key words
chemicals; dilution; environmental risk assessment; GIS; global-scale;
population; runoff