Hybrid receptor model approach

In my view, hybrid receptor models are the most likely approach for provide reasonable answers to the sulfate deposition problem within a time that they might be of use in influencing controls that may be imposed on S02 and NO sources. This does not mean that there is no need for further field studies. The Allegheny Mt. and Deep Creek Lake data sets were taken so close together that one would feel much safer if similar data were available at several other sites, e.g., the three sites of the Ohio River Valley study (20) and one or two sites to the northeast of Allegheny Mt.,... 

Diffusion Hybrid Receptor Model (Fay). This approach, beginning with the work of Fay and Rosenzweig (7), is perhaps the most interesting of all the hybrid models that have been proposed to date. Not only is it able to address the usual source apportionment problem of estimating source impacts (of SO2 and secondary sulfate) at a receptor site but it simultaneously generates estimates for the conversion and deposition rate constants and meteorological parameters that are influencing the pollutant transfer between source and receptor. Consequently, we choose to review this model in more detail than the others considered here. 

In this study we have employed the simultaneous collection of atmospheric particles and gases followed by multielement analysis as an approach for the determination of source-receptor relationships. A number of particulate tracer elements have previously been linked to sources (e.g., V to identify oil-fired power plant emissions, Na for marine aerosols, and Pb for motor vehicle contribution). Receptor methods commonly used to assess the interregional impact of such emissions include chemical mass balances (CMBs) and factor analysis (FA), the latter often including wind trajectories. With CMBs, source-strengths are determined (1) from the relative concentrations of marker elements measured at emission sources. When enough sample analyses are available, correlation calculations from FA and knowledge of source-emission compositions may identify groups of species from a common source type and identify potential marker elements. The source composition patterns are not necessary as the elemental concentrations in each sample are normalized to the mean value of the element. Recently a hybrid receptor model was proposed by Lewis and Stevens (2) in which the dispersion, deposition, and conversion characteristics of sulfur species in power-plant emissions... 

Three generic types of receptor model have been identified, chemical mass balance, multivariate, and microscopical identification. Each one has certain requirements for input data to provide a specified output. An approach which combines receptor and source models, source/ receptor model hybridization, has also been proposed, but it needs further study. 

Varady J, Wu X, Fang X, Min J, Hu Z, Levant B, Wang S. Molecular modeling of the three-dimensional structure of dopamine 3 (D3) subtype receptor discovery of novel and potent D3 ligands through a hybrid pharmacophore-and structure-based database searching approach. / Med Chem 2003 46 4377-92. 

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