A PRELIMINARY SCANNING ELECTRON MICROSCOPY (SEM) INVESTIGATION OF GREAT MIAMI RIVER SEDIMENT FROM HERITAGE PARK IN SOUTHWESTERN OHIO

The Great Miami River Buried Valley Aquifer (GMRBVA) is an EPA designated sole source aquifer that lies in southwestern Ohio, which supplies groundwater to 1.6 million people. This aquifer is recharged by small streams and precipitation that filters through the beds of sand and gravel; however, the main source of recharge is from the Great Miami River (GMR). The GMR, aside from being a significant contributor to the GMRBVA’s existence, is a source of recreation and fishing for residents along its’ banks. Sediment (sand and gravel) that comprises the aquifer’s extensive filtration system is also a prized resource along the entire length of the GMRBVA, spurring many quarries and dredging operations.

Despite the extensive use little is known about details of the mineralogy of the GMR. There have been no detailed scanning electron microscopy (SEM) studies of the river sediment and thus few details are known about the mineralogical variation that may be present. A preliminary SEM investigation was conducted on river sediment from Heritage Park in Colerain Township, Ohio approximately 15 km downstream of Hamilton, Ohio. Results indicate a level of mineralogical complexity within the sample set. In addition to common and abundant quartz and feldspar minerals, assemblages of rare earth element (REE) phosphate minerals are observed in the fine fraction of sediment. These are typically enriched in La and Ce and were subhedral to euhedral grains approximately 1 to 20 micrometers in diameter. Zircon is common, occurring as subhedral to euhedral crystals 10 to 50 micrometers in diameter. Barite occurs more rarely as euhedral crystals 0.2 to 5 micrometers in diameter and may be natural or anthropogenic. Possible coal ash spherules are also observed, which may be indicative of pollution stemming from the coal fired Hamilton Municipal Electric Plant upstream. This study has shown that there is a complex mineralogical assemblage in the sediment of the GMR, which due to lack of study is not well understood or recognized as a possible area for both potential economic and environmental concern. Further investigation of GMR sediment is warranted and may be of relevance regarding river bank filtration, water quality and the ecological health of the GMR overall.