Chemical analyses of elutriates, native water, and bottom material from the Chetco, Rogue, and Columbia rivers in western Oregon

Abstract

The U.S. Geological Survey in cooperation with the U.S. Army Corps of Engineers participated in an elutriation study in April and August of 1982. The purpose of the study was to collect reconnaissance data on elutriates, native water, and bottom material which could be used to evaluate short-term impacts of dredging and disposal operations representative of selected dredging sites in Oregon. Reconnaissance data were collected from the Chetco and Rogue River estuaries in southwestern Oregon and from the mouth of the Columbia River in northwestern Oregon to Cathlamet Bay, 18.2 miles upstream. In an elutriation test, bottom materials from a potential dredge site are mixed with native water collected from either a dredge or disposal site and the liquid portion of the mixture is removed, filtered, and chemically analyzed. Presented in this report are chemical and physical analyses of elutriates, native water, and bottom material for selected metals, ammonia, organic carbon, pesticides, particle size, and gas chromatographic/mass spectometric semi-quantitative organic scans. Elutriate and bottom-material samples were screened specifically for phenolic compounds, particularly the chlorinated phenols; phenol was the only compound identified. Elutriate-test results showed variability for selected trace-metal concentrations of dissolved chemicals as follows: in micrograms per liter, arsenic ranged from <1 to 15, cadmium from 1 to 210, copper from <1 to 13, chromium from <1 to 5, and nickel from 2 to 18. Comparison of 1982 reconnaissance data from the study with 1980 reconnaissance data shows: (1) 1982 minimum, median, and maximum concentrations for arsenic, cadmium, chromium, nickel, and zinc meet or exceed all 1980 minimum, median, and maximum concentrations for euryhaline elutriates, (2) 1982 minimum, median, and maximum concentrations for cadmium, copper, and nickel meet or exceed all 1980 minimum, median, and maximum concentrations for estuarine elutriates, and (3) 1982 maximum concentrations of DOT, methoxychlor, and perthane exceed 1980 maximum concentrations for bottom-material samples. Particle-size distributions of bottom material ranged from 98 to 2 percent finer than 0.125 mm. Dissolved oxygen and pH were monitored during elutriation tests; variations in dissolved oxygen ranged from near-oxygen saturation to complete-oxygen depletion; variations in pH did not exceed .3 pH units. Results of computations to determine the amount of a constituent associated with bottom material (sediment and interstitial water) and subsequently released (dissolved) into the eIutriate-test native mixing water are presented for selected trace metals. The highest elutriate-test release was 35 percent for manganese; the second highest, 5 percent for cadmium. All other computed releases were less than or equal to 1 percent. INTRODUCTI ON The U.S. Geological Survey, in cooperation with the U.S. Army Corps of Engineers, participated in an elutriation study in April and August of 1982. Elutriation is a process by which bottom materials .from a potential dredging site are mixed with native water collected from either a dredge or disposal site and the liquid portion of the mixture is removed, filtered, and chemically analyzed. The elutriation test is a simplified simulation of the various chemical and physical processes that occur when bottom materials are hydrauIicaI Iy dredged and transported as a mixture of bottom material and native water. The purpose of this report is to present reconnaissance data on elutriates, native water, and bottom material, representative of selected dredging sites, in Oregon. Chemical analyses were made for trace metals, ammonia, major ions, organic carbon, pesticides, and acid/neutral extractable organic compounds. Reconnaissance data were collected from the Chetco and Rogue River estuaries in southwestern Oregon and from the mouth of the Columbia River estuary in northwestern Oregon to Cathlamet Bay, 18.2 miles upstream (fig. 1). Native water and bottom material were collected by Oregon District personnel from the Geological Survey and Portland District personnel from the Corps of Engineers. Elutriation tests, with the exception of chemical analyses, were conducted at the Geological Survey, Oregon laboratory; samples of native water, elutriates, and bottom material were prepared for chemical analyses and shipped to the Geological Survey Laboratory in Arvada, Colo. Analyses of bottom material for particle-size distribution were made by the Materials Laboratory, U.S. Army Corps of Engineers, North Pacific Division, Troutdale, Oreg. Samples were analyzed as follows: 1. Native water and elutriates for selected trace metals, ammonia, organic carbon, pesticides, acid/neutral extractable organic compounds, hardness, pH, and specific conductance. 2. Bottom material for selected trace metals, pesticides, acid/neutral extractable organic compounds, percent moisture and particle-size distribution. 3. Elutriation tests monitored for temperature, pH, and dissolved oxygen. Field and laboratory procedures will be briefly outlined in this report; for further detail and information on earlier reconnaissance studies see Fuhrer and Rinella (1983). Sampling sites were selected by the Corps of Engineers, and designated as potential dredge or disposal sites. Figure 1 shows names and locations of project areas in Oregon.