AN ICP-MS AND SEM POLLUTION STUDY OF GREAT MIAMI RIVER SEDIMENT IN THE INDUSTRIALIZED LANDSCAPE OF HAMILTON, OHIO

The Great Miami River (GMR) coursing through the city of Hamilton in southwestern Ohio is representative of typical urban river/aquifer systems located throughout Midwest post-industrial regions. Detailed investigations of heavy metals in the GMR are sparse. Due to the extensive use of the river it is believed that such a study is warranted and overdue as there could be implications for water quality and the overall ecological health of the GMR. The portion of the river in Hamilton has a depth of ~20 m with a typical summertime flow of ≤1kcfs. A transect of samples were collected along the length of the GMR that runs through Hamilton and analyzed by ICP-MS, ICP-OES and SEM. Along this ~5 km stretch of the river several potential pollution sources are present, such as a coal fired power plant and storm water discharge. Approximately 30 storm drains lead into the GMR, funneling water off the streets of Hamilton into the river without filtration. ICP-OES data indicates that the majority of heavy metals are concentrated in the fine fraction (≤40 micrometers). Preliminary ICP-MS work indicates relatively strong correlations between Pb-Zn, Cu-Zn, Cu-Ni, Ni-Co and also correlations between Cu and Ni with Mn. Energy dispersive spectrums taken with the SEM also show a reoccurring relationship between Mn, Fe and Ti, suggesting that manganese oxides may be sorbing heavy metals out of this system. Additional SEM data from representative fine fraction samples revealed individual anhedral to subhedral lead particles (~8 micrometers in width), some of which show signs of weathering. Probable evidence of PbCrO₄ (yellow road paint) was found disseminated within a Ca, Si matrix, the euhedral lead chromate crystals were ~0.4 micrometers in length with 0.1 micrometer widths. Several masses of iron sulfide along with discrete subhedral to euhedral Ba-rich particles and coal spherules with varying intricate morphologies were also found within the samples. This investigation indicates that it is possible to identify sources of Pb pollution and coal derived pollutants in very mineralogically complex systems with bulk chemical and SEM analyses. This study defines pollutant particulates previously not recognized in the GMR system and provides constraints for environmental background in several contexts.