WHAM-Model

Lofts, S., and E. Tipping. 2011. Assessing WHAM/Model VII against field measurements of free metal ion concentrations Model performance and the role of uncertainty in parameters and inpnts. Environmental Chemistry 8, no. 5 501-516. 

Tipping E., 1994, WHAM - a chemical equilibrium model and computer code for waters, sediments and soils incorporating a discrete site/electrostatic model of ion-binding by humic substances. Computers and Geosciences 20,973-1023. 

Comparisons are made between the more recent data of Tipping et al. (1998) and those of Mantoura et al. (1978). Mant = Mantoura et al. (1978) WHAM = Windermere Humic-Aqueous Model M-FA = metal-fulvic acid. 

Tipping, E., Woof, C., Kelly, M., Bradshaw, K., and Rowe, J.E. (1995b) Solid-solution distributions of radionuclides in acid soils applications of the WHAM chemical speciation model. Environ. Sci. Technol. 29, 1365-1372. 

Correcting the quality standard for differences in availability using spe-ciation models (e.g., WHAM)... 

The thermodynamic equilibrium models, including surface complexation models, require the solution of a complex mathematical equation system. For this reason, many computer programs (e.g., CHEAQC, CHEMEQL, CHESS, EQ3/6, F1TEQL, Geochemist s Workbench, H ARPHRQ, JESS, MINTEQ and its versions, NETPATH, PHREEQC, PHRQPITZ, WHAM, etc.) have been developed to calculate the concentration and activity of chemical species, estimate the type and amount of minerals formed or dissolved, and the type and amount of sorbed complexes. 

Level 2 In the second level (Level 2), physico-chemical speciation models are introduced in order to correct the toxicity data for chemical availability. Indeed, NOEC and/or ECm values that are used in the effects assessment are generally generated in test media with varying physico-chemical characteristics (e.g. pH, hardness, DOC) known to alter metal availability and toxicity. In case metal concentrations are reported and appropriate speciation models (e.g. WHAM, MINTEQA2, etc.) and relevant input data (i.e. main physico-chemical parameters driving the availability of a metal such as pH, DOC, etc.) are available, NOEC and/or ECm values should be expressed on the basis of the metal species of concern in order to reduce uncertainty. Eor regulatory compliance purposes, the dissolved exposure concentrations should also be translated at the same level of availability (expressed in the same units) as the effects assessment. 

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