Distribution of Mercury and Other Trace Metals in the Wabash River, Indiana

There is very little information on mercury (Hg) and other trace metals (e.g., Co, Ni, Cu) in streams of central Indiana. Published research has focused mainly on the industrialized northern part of the State, close to Chicago, and on the Ohio River valley at the southern end of the State. For rivers draining the central part of Indiana, including the Wabash River, numerous Hg-based fish advisories are posted; yet, very little to no data on Hg and trace metals in water or sediments exists. We present some of the first Hg and trace metal data for the Wabash River in central Indiana. Water and surface sediment samples were collected in the summers of 2004 and 2005 from the river section that extends from upstream of Lafayette to Terre Haute. In contrast to the Wabash River upstream reaches, this section of the river has no water inputs from tributaries that drain reservoirs, and the above two cities as well as a power plant located upstream of Terre Haute are potential sources for Hg and trace metals to the river. Total-Hg concentrations determined on filtered samples ranged from 0.57 to 1.7ng/L in samples collected in August 2004, with very little change in concentrations a year after (range: 0.61 to 0.83ng/L). Total Hg levels in non-filtered samples ranged from ~1.6 to 5.0ng/L and from 3.31 to 4.17ng/L in August 2004 and 2005, respectively. These values compare to those reported for rivers and streams in neighboring states. Dissolved trace metal concentrations are generally low (e.g., Co, Ni, Cu less than 2μg/L) and show only small increases as the Wabash River passes through Lafayette. We will examine the relationships between aqueous Hg, sedimentary Hg (0.93-16.8μg/g) and Hg in biological tissues in comparison with trends/levels reported for other US rivers with similar land use types within watersheds.