Qualitative estimation of heavy metals in marine sediment using thermal analysis

This article proposes a method for the thermogravimetric analysis (TGA) of marine sediment suspected of pollution by heavy metals, which may be appropriate for a selected region where the regression equations relating W2 weight loss as the independent variable and estimated metal abundance as the dependent variable have already been derived. Automated TGA may then be employed as a reconnaissance tool, to give a rapid and inexpensive predictive index of quality. The method has been applied to actual samples of known heavy metal content and the results have been compared with the quality criteria for dredged sediment proposed by the USEPA and other standards. These criteria have been translated into the corresponding classification categories provided by the TGA method. The sediment samples, on which thermal analysis from 50 to 900 degrees C was performed, are from the southwest of Spain and several showed high levels of pollution. The first derivative of TG curves (DTG) and the chemical parameters analyzed were compared and those that provide better Pearson's coefficients were fitted by linear regression. From these fits several linear regression equations were proposed and taken as the basis for transforming the metal content values proposed in the USEPA and other international regulations in the form of TG data; finally, the method were validated by a certified material (MESS-3).