Modeling effects of moisture content and advection on odor causing VOCs volatilization from stored swine manure

Two models for evaluating the contents and advection of manure moisture on odor causing volatile organic compounds (VOC-odor) volatilization from stor ed swine manure were studied for their ability to predict the volatilizatio n rate (indoor air concentration) and cumulative exposure dose: a MJ-I mode l and a MJ-II model. Both models simulating depletion of source contaminant via volatilization and degradation based on an analytical model adapted fr om the behavior assessment model of Jury et al. In the MJ-I model, manure m oisture movement was negligible, whereas in the MJ-II model, time-dependent indoor air concentrations was a function of constant manure moisture conte nts and steady-state moisture advection. Predicted indoor air concentration s and inhaled doses for the study VOC-odors of p-cresol, toluene, and p-xyl ene varied by up to two to three orders of magnitude depending on the manur e moisture conditions. The sensitivity analysis of both models suggests tha t when manure moisture movement exists, simply MJ-I model is inherently not sufficient to represent a more generally volatilization process, which can even become stringent as moisture content increases. The conclusion illust rates how one needs to include a wide variety of manure moisture values in order to fully assess the complex volatilization mechanisms that are presen t in a real situation.