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.'d'sble 1. Mean NH.HCOrDTPA eztnefabk levels of dements ehovring Uttle m no redlstrlbatlon k retarked shale plots after B fir. As Cd l:n Fe Ms NI Pb Se Zn M/8 7bpeoil 0.2 0.02 1.8 6.7 1S 0.9 O.B 0.6 0.6 RetoRed shale 2S 0.19 6.6 276.0 16.0 1.0 9.6 l.6 120 It should be emphasized that this study does not con- sider movemrnt of tray elements and salts within the plant root-shoot system. It haz bernwell documrnted that plants in and ecosystems may act az biological "pumps" by taking up salts and trace elements from subsoil layers and redepositing them on the soil surface (Roberts, 1950; Fireman and Hayward, 1952; Rickard and Kceugh, 1968; Jessup, 1969; Sharma and Tongway, 1973; Kline and McKell, 1974; Charley and West, 1975; Tiedemarin and Klemmedson, 1973). Although the surface soil samples collected in this study did not show elevated levels of salts or trace elements on any of the plots containing buried shale, plant samples collected on plots with shale had higher trace elemrnt concentrations than those on the control plot (Redente e[ al., 1985). Thlu, the biological "pumping" process may become an important mxharlism !or trace elemrnt and salt movement in future years. Of the topsoil treatments considered, the capillary baz- rier treatment was the most effective at preventing up- ward movement of salts and trace elements. Figures 2 to 4 show thatthe soil immediately above the capillary bar- rierhad no higher EC, SAR, or trace element concentra- tion than the rest oC the topsoil. Unfortunately, in this treatment the retorted shale rested directly on bedrock, so it was not possible to tolled samples to determine the amount of downward movement. Figures 2 to 4 also show that in general, retorted shale layers covered by the greatest topsoil depths had the least amount of salt and trace element movement in either direction in the profile. Apparsotlyathe.deepea4hashalC.,' layss~,cb~udodrr~t~e ,iess.it=israffeded•by ~leachingsan~ capillaty~effects; Alter 6 yr in the field, the exposed shale treatments (both leached and unleached) continued to have the highest sal[ and trace element concentrations within the upper 60 cm compared to all other treatments. Although leaching reduced EC and SAR somewhat, EC and SAR still remained too high to allow all but salt tolerant plan[ species to survive. These results are interesting considering the results of other leaching studies on retorted oil shale. After perfor- ming aseries of laboratory lysimeter studies on Paraho retorted shale, Fransway and Wagenet (1981) reported that two pore volumes of leaching water were required to reduce EC to acceptable levels (<4.0 dS m 'within the upper 60 cm of shale). In addition, they reported [hat the most effective application procedure waz to apply 0.44 pore volumes at either 7.4- or 72-h frequencies. Although the leaching procedure used in this study followed these recommendations quite closely (0.43 pore volumes were applied at 24-h frequencies for a total of 2.6 pore volumes), EC dropped below 4 d5 m ' only in the top 15 cm of shale. Two factors could be causing the PERCENT SOIL MOISTURE (by Hl ~.o s.o It.o Ifi.o eoo I--1 I.e - Central --- a0 ew Tep.ell -~- 90 ew TaNell E a0.0 ~ .°. ~ _ ~ ``~ t- d ~ y j 60.0 1 ~ ` o ~ j O1 ao.o ~ ~ ~ \. ) ~/ tto.o F{g. S. GnTlmetrk Boll molstorc In tonlrsl, 30-, and 90aTn lopsoa untmeslr k 4te Asgmt 1983. PERCENT SOIL MOISTURE (b~ rt) ~.o s.o 12.o Ie.a ro.o - B/ea `. e ao.o ` ° ` t~ I.e T x I ~ t ydj 60.0 I 0 1 J l o f °' Bo.o 1 l i r tzo.o Fig. 6. Crerlmetrk so0 moW me k the rnnlrol plot In Isle August 1983 sod Isle Mar 198A. discrepancy between the laboratory data of Fransway and Wagenet (1981) and our field data: (i) natural weather- ing of the shale during the 2 yr between leaching and soil sampling may have resulted in the release of additional soluble setts, or (ii) underlying substrata in the field plots may have restricted drainage and prevented efficient removal of the soluble salts. In the study area evapotranspiration usually equals precipitation, and deep percolation of moisture rarely oc- curs (USDA-SCS, 1982). Gravimetric soil moisture data was collected on the plots using soil cores to determine if the retorted shale layers were resulting in deep percola- tion of moisture. Figure 5 shows the soil moisture con- tent of the control, 30-, and 90-cm topsoil treatments at the end of the 1983 growing season. Soil moisture was depleted throughout the entire 120 crrl in the control plot, while in the 30- and 90-cm topsoil treatments it had only been depleted down to the top o(the shale layer. These zones of depletion coincide fairly well with rooting depths observed in soil pits.{~LelloOnA>Qakyloppmolsstttmrdedex,- r}ntdgpihs~t 1(rRSm~or~aort.~tilaimthe;~0-,ends9Q-elm-~ J. Environ. Qusl., Vol. 15, no. 3, 1986 287 _~_ t I ,.