EVALUATION OF COPPER ACCUMULATION IN PART OF THE CALIFORNIA AQUEDUCT¹

Abstract

Copper sulfate has been used extensively in the California Aqueduct to control phytoplankton and the alga Cladophora. Since 1969 more than 250,000 pounds of copper sulfate has been added to a part of the aqueduct. Although copper sulfate is effective in controlling algae, copper tends to accumulate in the system in which it is applied. Samples of water, biota including plants, clams, and snails, as well as sediment were analyzed for copper. Results of these analyses showed that copper concentrations in the water, with three exceptions, were less than 10 micrograms per litre. Samples of plant tissue showed a 198 percent increase in copper concentration in the treated reach of the aqueduct, and clam tissue showed a 68 percent increase. Snails in the treated reach had 77 percent more copper than in the untreated reach whereas copper concentrations in the sediment doubled. None of the concentrations found are considered to be harmful to the biota.

Heavy Metals in Natural Waters

“…Several field studies have shown that there is no accumulation through the food chain. Copper sulfate was added to an irrigation canal in California (USA) to control algae, resulting in water, sediment, and vascular residues of~O.OIO mg kg-I, 30-60 mg kg-I, and 35 mg kg-I dry weight, respectively (Fuller and Averett, 1975). However, molluscs (Corbicula sp.)…”

Effects of copper on humans, laboratory and farm animals, terrestrial plants, and aquatic life

“…Similarly, biotic samples (plants, clams) showed increased copper concentrations in the treated reach compared to the untreated reach. 96 In a similar situation (algal control of Lake Perris reservoir in Southern California), Elder and Home 97 found that the added copper is converted eventually to particulate forms but that the conversion is relatively slow: after 4 weeks most of the copper was still in solution.…”

Combinations of Diquat and Several Cations for Control of Hydrilla (Hydrilla verticillata)

“…There are published and unpublished reports that extensive use of copper has resulted in the accumulation of several hundred ppm of copper in aquatic soils and sediments. Accumulation of copper by sediments and living organisms in continuously flowing systems, such as rivers and canals, was reported to be minimal (4). However, in more confined lake systems, the use of copper sulfate as an algicide increased the levels of copper in lake sediments to as much as 60S ppm (8).…”