Numerical Water Quality and Contaminant Modeling. The Environmental Laboratory announces research opportunities involving numerical water quality and contaminant modeling. This area of research involves development and application of water quality and contaminant fate/transport models for both surface water and the subsurface, or groundwater. Emphasis is on formulation of the appropriate physical, chemical and biological algorithms; improvement of mathematical and numerical methods; collection and assemblage of data for model evaluation; conduct of field and laboratory process investigations designed to develop/improve model descriptions; dynamic linkage of water quality and biological models, including biomass-based, individual-based, and population-based biological models; integration of contaminant exposure models with biological effects data or models to quantify risk; incorporation of uncertaintly analysis into modeling; and development of software to provide graphical user interfaces and modeling environments to enhance model utility and ease of application.