Heavy metal concentration in sediments of the White River watershed in Muncie, Indiana: a preliminary study

Despite river sediments being known as long-term "sinks" for industrial pollutants, little investigation has been conducted on the potential contamination of heavy metals in the sediment of the White River in Muncie, Indiana. The current study investigated the concentrations of heavy metals and metalloids (lead, copper, cadmium, chromium, nickel, arsenic) present in sediments of the White River throughout the city of Muncie and additional samples from Winchester and Anderson. A total of twelve sediment samples were collected from selected locations along the river, together with two samples collected at tributaries to serve as background samples. The collected samples were dried, pulverized, microwave-digested, and analyzed via ICP-MS following EPA methods 3050B and 6020B. The sediment samples revealed metal concentrations (in mg kg−1) as follows: Pb (3.9-78.9), Cr (5.1-43), Cu (6.1-39.8), Ni (4.7-25.4), As (2.0-6.2), Cd (0.11-1.92) and Al (2060-8040). One notable discovery is that the average mean concentrations for Pb and Cu surpassed the acceptable limits set by the USEPA (1999), with Cd teetering on the edge. According to toxicity reference values (TRV), the Cu, Cd, and Pb concentrations in both Muncie and Anderson downstream areas alarmingly exceeded permissible sediment limits, hinting at a significant pollution issue. Using standard indices such as contamination factor (Cf), pollution load index (PLI), enrichment factor (Ef), and the geo-accumulation index (Igeo), we discerned varied contamination degrees. Muncie and downstream Anderson sampling sites displayed moderate to pronounced contamination, specifically with metals in the order Pb > Cu > Cd > Cr > Ni > As. The Igeo underscored this, designating Cu, Cr, and Ni as prominently contaminated and elevating Pb to an extreme bracket, while As and Cd remained relatively subdued. Intriguingly, EF assessments pinpointed Cr and Ni's primarily natural origins, whereas As, Cd, Cu, and Pb seemed largely anthropogenic, possibly emanating from industrial and urban sectors. The widespread contamination in Muncie and Anderson samples demands attention. These assessments offer vital insights for future environmental strategies addressing heavy metal contamination in the study area.