Category
Environmental models
Capabilities
WHAM is a mechanistic chemistry process model. Given the chemical composition of a water or soil, WHAM predicts the amounts of each chemical species of metals present. Metal speciation controls fate in the environment, for example the distribution of a metal between solids and porewater in a soil or sediment. Hence WHAM includes a solution speciation model as well as sub-models for ion binding to: humic and fulvic acids; clay; oxides of iron, aluminium, manganese and silicon.
The WHAM-FTOX version predicts the toxic effects of mixtures of metals and acidity in freshwaters.
POSSMs computes a simplified distribution of metal forms in soil using a minimal input dataset, making it useful for application where the relatively large data requirements of WHAM cannot be met (eg large scale soil surveys).
WHAM is also used as the chemical component in other models that predict how water chemistry affects the toxicity of metals to aquatic organisms, such as the freely available Biotic Ligand Model (BLM): such models are widely used for research and metal risk assessment.
Lifecycle
WHAM was originally developed in 1994 by Ed Tipping from earlier, simpler models. Subsequent upgrades improved the predictive capability of the model and expanded the number of metals to which it can be applied (currently more than 40): WHAM-Model V (1994); WHAM-Model VI (2002); WHAM-Model VII (2011).
POSSMs was developed was developed by Stephen Lofts in 2022 from earlier semi-empirical models, supported by NERC National Capability funding.
https://www.ceh.ac.uk/services/possms
Partners
The WHAM family of models were developed by UKCEH.
Access
WHAM is available to use via a licence purchase (see weblink). Income from licence sales contributes to ongoing development and support of the software.
POSSMs is available at no cost as an Excel add-in.
Funding sources
Development of WHAM was funded by: UKRI-NERC National Capability and research grants; International Copper Association (ICA); International Council on Mining and Minerals (ICMM); International Lead Zinc Research Organization (ILZRO); Nickel Producers Environmental Research Association (NiPERA); Cobalt Development Institute (CDI); Rio Tinto Minerals; International Chromium Development Association (ICDA); International Molybdenum Association (IMOA); European Aluminium Association (EAA).
POSSMs development was funded by UKRI-NERC National Capability: UK-SCAPE programme (SPEED project).
Users
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WHAM is used by UKCEH and researchers at more than 100 labs around the world for metal risk assessment (including UK Health and Safety Executive REACH: registration, evaluation, authorisation and restriction of chemicals).
Last updated
28 November 2023 16:18
