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<br />TOXICITY OF LEACHATES FROM RETORTED OIL SHALE
<br />
<br />891
<br />
<br />TABLE 3, - Mean (SD) concentrations of selected cations and anions (mg/L) in test dilutions of spent shale leachate
<br />during partial-chronic toxicity tests with fishes, ND = not detected, <0,01 mg/L
<br />
<br /> Leach-
<br /> ate
<br /> concen-
<br /> tration
<br /> (%) B Ca K Li Mg Mo Na Sr F CI NO) S04
<br /> 0 0,16 36 5,8 0,05 21 NO 49 0,24 0,61 22 NO 48
<br />~, (0,0) (0,9) (0,3) (0,0) (OA) (32) (0,01) (0,04) (OA) (0,7)
<br />'f 40 4.1 793
<br /> 6 0,19 50 35 OA7 142 0-32 164 057 0,96
<br /> (0,0) (IA) (0,8) (0,01) (5) (0,01) (5) (0,01) (0,04) (0,9) (0,88) (15)
<br /> 25 0,29 93 III 1.69 487 1.26 493 1.57 1.93 95 20 3,086
<br /> (0.01) (5,6) (7,6) (0,09) (28) (0,04) (15) (0,04) (0,07) (1.7) (0,9) (51)
<br /> 100 0,65 242 368 6,0 1,648 4,7 1,688 5,3 6,9 317 86 11,888
<br /> (0,01) (3) (II) (0,1) (8) (0,06) (26) (0,1) (0,1) (I) (0,5) (81)
<br />
<br />
<br />ber of young per adult was similar at day 21 for
<br />both the control and 25% preparation. However,
<br />adverse biological effects were observed on may-
<br />flies and both fishes during 30-d exposures to the
<br />leachate (Table I). Survival of all three species
<br />was reduced (P ::s 0.05) from that in the control
<br />at day 30 in concentrations of 13% leachate and
<br />. greater. Survival of mayflies and growth of fat-
<br />head minnows were the most sensitive biological
<br />responses and were adversely affected by the 6%
<br />i preparation. Survival and growth of organis.ms
<br />.. from the control and the lowest concentratIOn
<br />, (3%) were not significantlY'different (P > 0,05).
<br />.i
<br />. In chronic toxicity tests, the water quality
<br />~, characteristics of the leachate test solutions (Ta-
<br />Jt,',,' ble 2) were similar to those expected after dilu-
<br />tion with laboratory water, Due to the ions pres-
<br />ent in the dilution water, conductivity and
<br />hardness were higher in the 25% preparation than
<br />I would be expected by calculation from the full.
<br />i strength leachate, The concentration of most ma-
<br />I jor ions in expOsure waters (Table 3) did not vary
<br />fover the course of the experiment. Nitrate and
<br />~ nitrite were exceptions; as the study progressed,
<br />',,' "".,.nitrate concentrations dropped and nitrite con-
<br />centrations increased, possibly because of bac-
<br />, terial activity. However, un-ionized ammonia
<br />was always below 0.02 mg/L during the study.
<br />Concentrations of most inorganic elements in
<br />i fish tissue indicated no direct relation between
<br />:' aqueous concentrations and concentrations ab-
<br />I s~rbed and .retained i~ the fish (Ta?le 4), Excep-
<br />t hons to thIS were LI and Sr, whIch showed a
<br />: direct correlation between water and tissue con-
<br />,; centration in both fish species. Molybdenum, an
<br />~ element that was high in the leachate, was not
<br />l"'o<entmted by Colomdo 'quawfi,h; howev",
<br />
<br />concentrations were elevated in fathead min-
<br />nows from the 25% and 13% leachate exposures.
<br />An inverse relation ofBa with increasing percent
<br />of leachate in both fathead minnows and Colo-
<br />rado squawfish was probably caused by increased
<br />S04, which limits the solubility of Ba.
<br />Mean concentrations (SD) of organic carbon
<br />were 7.7 (0.4) mg/L in the raw leachate and 2.7
<br />(0.3) mg/L in the 25% preparation. Background
<br />concentrations in laboratory water and in the
<br />control water were 1.3 (0.6) and 1.5 mg/L, re-
<br />spectively. Concentrations in other test prepa-
<br />rations were intermediate between these. Mea-
<br />sured values for all exposure concentrations
<br />agreed with values predicted on the basis of
<br />dilution. However, concentrations of organic
<br />carbon in the greater dilutions were near
<br />background, making correlations difficult. Nitro-
<br />gen-containing organics were not elevated in the
<br />25% preparation nor in tissues of either fish
<br />species from any of the four test dilutions in
<br />relation to the control fish or control water.
<br />
<br />Discussion
<br />
<br />Concentrations of chemical constituents in re-
<br />torted shale leachate are variable because of the
<br />differences in shale sources, retort processes, and
<br />research methods. Snyder and Snyder (I 984), who
<br />recently reviewed the quality of leachates from
<br />various spent shales, reported values for TDS
<br />ranging from 10,000 to 50,000 mg/L and pH
<br />from 7 to 10. In comparison to surface waters,
<br />spent shale leachate was 10-150 times more con-
<br />centrated in major cations and anions and 10
<br />times more concentrated in trace elements. Val-
<br />ues for TDS, pH, and major ions in the leachate
<br />used in this study were within the reported ranges,
<br />
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