PH16 Metals in the Environment: Chemistry and Fate Issues
Exhibit Hall
8:00 AM - Thursday, 13 November 2003
(PH163) Metal Speciation and Transport in the Black River of Missouri's New Lead Belt.
Faeth, A1, Wronkiewicz, D1, Adams, C1, Mendoza, C1, McBurnett, J1, Wolf, S1, Krizanich, G1, Struttman, S1, 1 University of Missouri – Rolla, Rolla, MO, USA
ABSTRACT- A study is being conducted on the West Fork of the Black River in Missouri's New Lead Belt to characterize the speciation and transport of particulate and dissolved heavy metals in a carbonate-dominated river system (pH varies from 7.6 to 8.2). Water chemistry, sediment composition, particle size distribution, mineral speciation, and flow modeling are being evaluated to characterize the path by which metals are transported during varying hydraulic events. Six sites are being sampled periodically to characterize transport during both seasonal and storm-induced stream flow variations. Information from this study will be used to evaluate metals transport processes in the Black River. This information will also be incorporated into the EPA Unit World Model used to predict metals transport in aquatic systems. The present study includes analyses by optical microscopy, ICP-MS, ICP-OES, XRD, SEM, and IC, as well as a variety of other in-situ and laboratory measurements. ICP-MS data from water samples collected during normal stream flow conditions showed low lead and zinc concentrations. These values increased downstream from the control site, located above any zones of mining, to sites located downstream from tailings ponds. Lead and zinc concentrations from unfiltered water samples collected at the control site were <0.25 and 13 ppb, respectively. Concentrations increased downstream from mine tailings piles where a maximum of 6.7 ppb Pb and 163 ppb Zn were detected. Overall metal contents also increased for all sites during an unanticipated period of gravel removal upstream from the sampling reach. This sediment disturbance completely dominated the lead distribution patterns, masking any input from the three mines located in the watershed area. The disturbance may mimic, in part, potential transport pathways for metals during flood events.
Key words: metals, lead, sediments, transport