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<br />biomagnification in the food chain (Forstner and <br />Wittman. 1979 1581). Bioassays by Warnick <br />and Bell (1969) [1591 on three species of inver- <br />tebrates Istonefly. Acroneuria Iycorias; mayfly. <br />Ephemerella sub varia; and caddisfly. Hydro- <br />psyche betteni) indicated that in most instances <br />aquatic insects are not as sensitive to heavy <br />metals as are fish. <br /> <br />Manganese <br /> <br />Manganese is not found pure in nature. but its <br />ores are common and widely distributed. It is <br />usually present in surface waters in concentra- <br />tions in excess of 1.0 mg/L (McKee and Wolfe, <br />1963 110511. The toxicity of manganese to <br />fish and other aquatic organisms depends upon <br />many factors. Jones (19391 1881 gives the <br />lethal concentration for the stickleback as <br />40 mg/L. Schweiger (19571 11341 reports <br />that tench. carp, and trout tolerate 15 mg/L for <br />7 days. Various forms of manganese may <br />actually be antagonistic to the toxic effects of <br />other heavy metals IBlabaum and Nichols, 1956 <br />11111. For the protection of aquatic life. Davies <br />and Goettl (19761 1341 suggest that <br />manganese should not be present in cold surface <br />waters in excess of 1.0 mg/L. <br /> <br />'ron <br /> <br />Iron is important as a component of the oxygen- <br />carrying protein molecule of blood (Forstner and <br />Wittmann. 1979 1581), According to South- <br />gate (1948) 1141 J. the toxicity of iron depends <br />on the ionic state and whether it is in solution or <br />suspension. The deposition of iron hydroxides <br />on the gills of fish may cause irritation and <br />blockage of the respiratory channels (McKee and <br />Wolfe. 1963 [1051). Hart et al. (19451 1711 <br />state that 95 percent of the waters that contain <br />good fish fauna in the United States have iron <br />concentrations of less than 0.7 mg/ L. Ebeling <br />(1931) 1441 reported that 10 mg/L of iron <br />caused serious injury or death to rainbow trout <br />in 5 minutes. Lee (1973) 1961 reported that iron <br />in solution greatly affected the toxicity of other <br />metals as well as the size of organic particles. <br />Davies and Goettl (19761 1341 recommend that <br />iron should be present in concentrations no <br />greater than 0.5 mg/L for the protection of <br />aquatic life. <br /> <br />Copper <br /> <br />Copper appears to have a synergistic effect on <br />zinc toxicity (Doudoroff. 1957 1401; Lloyd. <br />1961 [1001; and Eaton. 1973 14211. It is not <br />considered to be a cumulative poison and most <br />of the copper ingested is excreted. The toxicity <br />of copper to aquatic organisms varies signifi- <br />cantly between species as well as with the phys- <br />ical and chemical characteristics of the water, <br />such as temperature, hardness, turbidity. and <br />carbon dioxide content (Tabata. 1969 [146, <br />147, 1481; Tabata and Nishikawa, 1969 <br />1149]; Rehwoldt et al" 1972 11271; and <br />Pagen-Kopf. et al., 197411231 I. Chapman and <br />Stevens (1978) 1231 found that the 96-hour <br />LC" values for copper were 0.046 and 0.057 <br />mg/L for coho salmon and steelhead trout. <br />respectively. (A 96-hour LC" is the concentra- <br />tion of an element which will kill 50 percent of <br />the test organisms in a 96-hour test.1 <br /> <br />Copper is usually present in surface waters in <br />the United States in concentrations of 0.001 to <br />0.010 mg/L. It is a micronutrient for plants and <br />animals. but may be toxic at only slightly higher <br />concentrations (Environmental Protection <br />Agency. 1978 15111. Chakoumakos et al. <br />119791 122) found the toxicity of copper to be <br />inversely correlated with alkalinity and hard- <br />ness. In a literature review by McKim et al. <br />(19751 11071. it was stated that copper is <br />acutely toxic to rainbow trout in concentrations <br />of 0.25 mg/L. while survival and growth were <br />maintained in brook and rainbow trout at con- <br />centrations of 0.0094 and 0.015 mg/L. <br />respectively. McKim and Benoit (1971) 11061 <br />also found that concentrations of copper of less <br />than 0.0174 mg/L in water of 45 mg/L hard- <br />ness (as CaCO,) did not affect the survival, <br />growth. or reproductive success of brook trout. <br />Goettl et al. (19741 1651 found that trout <br />accumulated copper in liver tissue after ex- <br />posure to concentrations of only 0.003 mg/L <br />Cu. Baseline concentrations for copper in rain- <br />bow trout on a dry weight basis in I'g Cu/g <br />were: muscle 1.7. gill 4.9. and kidney 12.9 <br />(Goettl et al.. 1972 1641 ). In studies with the <br />stone loach, Sol be and Cooper (19761 11401 <br />found that liver tended to retain copper. <br /> <br />Davies and Goettl (1976) 1341 recommend that <br />copper concentrations not exceed 0.01 mg/L <br />in cold waters. Standards recommended by the <br />Environmental Protection Agency (19801 1531 <br />suggest that at hardnesses of 50. 100. and <br /> <br />12 <br />