The following methods were used in the study:
Fish were caught by rod and reel method using a Community Based Participatory Research approach. We recruited local anglers to catch fish for study because the study done by Joanne Burgher showed that the anglers usually caught bigger fish than scientists. We want to use the proper sized fish to do risk assessment.
10 to 15 catfish were caught at each location.
From each fish, 0.5 gram of catfish fillet was microwave digested in nitric acid. All trace elements except Hg were analysed by collision cell ICP-MS with calibration by the method of standard additions. Mercury was analysed by isotope dilution cold vapor ICP-MS (Inductively Coupled Plasma Mass Spectrometry).
The data were log-transformed and analyzed by ANOVA with tukey post hoc comparisons and independent T-tests using SPSS software, edition 15.0.