Trace metal transport from mining, milling, and smelting watersheds

The New Lead Belt of southeast Missouri has become the producer of 80% of the lead needed in the U.S. Because the district is located almost entirely within the boundaries of Clark National Forest, and because the area abounds in wild, unpolluted, and uninhabited stream basins, the area has become a laboratory for the study of lead and zinc in the aquatic environment. This study took advantage of this natural region to evaluate the effects of the new, large lead and zinc mining, milling, and smelting operations on the chemical and physical quality of the aquatic environment. Twenty-three sampling sites were used for aquatic measurements during the study. Maximum and minimum values for the concentrations of Pb, Zn, Ar, Cd and Mn and their mass flows are tabulated. Average values for the physical and chemical properties of the water at the twenty-three sampling stations are also given. Results indicate that under normal nonrunoff conditions, the receiving stream physical and chemical water quality below the mining, milling, and smelting operations of the New Lead Belt is not radically different from that of the control streams in the region. The only significant difference is that turbidity and suspended solids levels were slightlymore » higher in receiving streams and that heavy metals were found to be associated with the solids. These particles may either fall to the sediments or be carried with the normal stream flow. The data on runoff indicate that runoff transport is a major mechanism for moving metals that are emitted by mining, milling, and smelting operations from one ecosystem to the next. It is also apparent from the data presented that neither normal flow nor runoff was responsible for the bulk of heavy metal transport during the study period; both were responsible for significant transport.« less