Mentor: Jason Rech, Ph.D.

Urban gardens provide valuable opportunities for community engagement and enhance the overall well-being of those they serve. Despite these attributes, soils in metropolitan areas often carry a legacy of heavy metal contamination due to industrial activity and urban waste. This study examined the soil chemistry of 118 samples from four community gardens, referred to as EE, PH, TT, and WT, to assess the concentrations of five heavy metals: Arsenic (As), Copper (Cu), Lead (Pb), Mercury (Hg), and Zinc (Zn). Ohio’s maximum allowable concentration (MAC) is 68 ppm for As, 50 ppm for Cu, 100 ppm for Pb, 0.045 ppm for Hg, and 100 ppm for Zn.Through the use of X-ray fluorescence, we determined that As and Hg are below Ohio EPA MACs or are below detection limits. Conversely, elevated concentrations of Zn, Cu, and Pb in soils were found that exceed Ohio’s recommended levels, which are based on ecological and human health screening guidelines. In total, seven (6% of total) samples from gardens PH, EE, and WT exceeded the MAC for copper and six (5% of total) samples in GardenEE were found to exceed the MAC for lead. Most noticeably, there were 76 (64% of total) samples from all four gardens that exceeded recommended levels for Zinc. It should be noted the natural average abundance of Zn in southwest Ohio is ~70 ppm, which is close to regulatory threshold values and background concentrations reported in regional soil studies. The area with the overall highest levels of Zn is Garden PH and the area with the highest levels of Pb is Garden EE.

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