Document YD525rXO4eQdgpBqbOGg6NprK

Migration of Polychlorinated Biphenyls in Soil induced by Percolating Water by E.S.Tucxtn, W. J.LmcKCi, and W. M. M ees Monsanto Company 800 iS' Lindbargh Boulevard Sc. Louu, Mo. 63166 The thermal and chemical stability of the polychlori nated biphenyls (PC3s) are clearly responsible for their widespread us in the electrical industry. U n fortunately, aany of the environmental concerns about PCBs are attribute:!" t o the same properties. Where fire resistance a x d efficient transmission of electri cal energy are important, PCBs are the preferred di electrical fluid. It: fact, the U.S. Government's Interdepartmental "Task Force on PCBs, PCBs I K THE HNVIRONMENT (1?"2; concluded that for closed systems such as transformers and capacitors there are no suit able replacement rrtcucts for PCBs. Consistent with these conclusive., '-ensanto introduced a new PCB product, A x o c l ! . . i , containing substantially less of the degxadat::. -i. -."ant higher chlorinated iso mers, restricted i t rales to use in closed systems, and set up a hi;- srature incinerator for disposal of used fluids. incineration is an acceptable solution to the c c-ral of used fluids, it is not feasible for m;v/ -.cr.s at this point in time for disposal of PCB *g-iated material from transformers and capacitors. The objective o : i tudy was to produce data which would help eval-.'s ..\e suitability of landfill dis posal of Aroclcr _ .6 impregnated capacitors. Of prime concern v r * rets at which percolating ground water might lea r 1016 from various types of soils. experimental The experimental procedure employed consisted of per colating water through a column packed with soil coated with Ar:> or 1016 and then monitoring the ef fluent water fc. FCBs. The set up used is shown schematically L. Figure 1. The soil columns employed are approximately 3" in diametftr by 12" in height and were dry packed in layers. Each soil layer being 3" * agiatarad trademark: of Monsanto Company 6 kllMla1IirtiwiulOm.mnMUa 41Tw4tt. vi. u. rw. i in hy n i t u. NPC00016236 207922 i FIGURE 1. SOIL PERCOLATION SETUP 17 \ NPC0001$237 ir 207923 * thick - first unc>.* . with 2.5t (v/w) of layer of uncoatcf . clor 1016 was u-i*. lowed by removal -il, followed by soil t: r 1016, and finally ano An acetone solution of . . u the air dried soil. : cetone in a rotary eva: Three differed: : study. The cha: .: Table I. oils were used in thi. .cs of each are shown i: ccvp: So il X Sand X Silt t Clay t O rg an ic Carbon 3 1ABLE 1 c s o il s used ih study Ray 0 n a ">- _>v S i l t y Loaai S f 1car CV 6 .2 2. 3 .2 5?. 5-6 351.0 6.0 The intent was to which could be er. The soils and t.*-.* eraluate the soil Distilled water stant pressure tc were observed tc then decrease a;, wetting phase sc-\. becomes compress, most pronouncec >. flow rates in. litt Silty Loam and Dru; 0.32, respectively. The effluent wai passed through t titatively absor: carried out on a . polyurethane fear manner, the effl*. The PCBs were r; elution with 2'. : the various soil type; 1 at different landfill re employed have been u* ' of agricultural chemic: rom the reservoir at a c. :1 column. The flow rat. the first few days, and .at. Apparently, after tin ._ing occurs until the sc., column. This effect u t ility soils. The average for Norfolk Sandy Loam, k. ..Ity Clay were 0.26, 0.53 .'e soil column was in tu: i .rvane foam column which c ; . 5HSSER (1971). Sampling :c basis by interchanging < for the old column. In t Vi be continuously monit: from the polyurethane by .tone followed by 100 mi 33 N p C 0 0 0 z 6J 3 8 207924 nanograde ;nt ;d collected in a 250 al separatory funnel. T;.. .. ..us phase was discarded and the hex- ane layer v :sred through anhydrous sodium sul- fate into a '.a-Danish evaporative concentrator, The hexane r rate was transferred to an aluminat column and * -ith 125 ml of hexane. The hexane eluent was c -rated in a Kundema-Danish evapora tive concern te and analyzed using a gas chromato- graph equip;, :r. an electron capture detector. The conditions r u t gas chromatographic analysis were as follows: Instruaar.t H e w lett-P ack ard Model 5753A Cas Chromatograph (HI-63 E le ctro n Capture D etecto r) Column; 2M x k im kX XE-60 ill loan on . 80/100 Hash Chromoaorb tf High Performance * Glass In jectio n Column T n : t D e te cto r Ten-. . C arrier Purge- Gai Pulse Int* -- >eracure: e: 220*C 170*C Isothermal 300*C Helium, 60 el/min. lOt Methane/Argon, 120 el/aln. 50 usee rults and Discussion The poiyu r cn day* I I SUX. i efflu 9 i '..;t .va columns were changed and analyzed : i f 31, 39, 52, 98 and 185. Table . i svels of PCBs found in the column B reak :. ; PCBs in the effluent water was re lated - r .. .i montent of the soil. The soils con- ta in i! .if V L sis of clay retained the PCBs. The ordr r . . i b akthrough occurred as a function of e fii-u . Norfolk Sandy Loan followed by Ray S . ..* .* 0. . finally Drummer Silty Clay Loam t 4L .. 2b . - - .vatc; j . i dfi . TC J. -i.-v.. -Sj a . \ie grade, 80/200 aaab, heated at 400 *C :-rated with 5% (w/w) dietilled water, into a gLa*a chromatographie column wd with 2 cm of anhydroua aodiua sul3 ml of nanograda hexane before ad- nPC00016?39.- 207925 TABLE II PC8l FOUND IN PERCOLATING WATER N orfolk Sandy Loam Total Effluant ppb Volume (t) PCBs (Uy Silty Loem Total Effluant ppb Voluraa (t) PCBs Drummer Silty C Iav Loam Total Eff1uen; DOb Vo tune ( l ) PCBs 1.3-8.1 NO 2.7-16.4 10.1 ND 20.7 13-5 23 27.6 25.5 63 51.9 48.1 63 98.1 NO - Non datactad, <1 ppb NO 65 92 153 134 1.6-9.9 12.5 16.6 31.4 59-2 NO tu NO NO NO (none observed). This is in agreement with recent work, HAQUE (1974) , demonstrating that clay has a high affinity for PCBs. Experimentally, the water solubility of Aroclor lOlf has not been determined; however, it is estimated to be in. the range of 225*250 ppb. This estimate is based on the fact that Aroclor 1016 contains nor* t the less chlorinated, more water soluble isoneri l -.c: does Aroclor 1242 which has a water solubility of 200 ppb. In all cases, the concentration of PCBs in the effluent water was less than the estinated solubility of Aroclor 1016 in water. The electron capture chromatograms shown in Figure 2 detail the isomer distribution of the PCBs observed in the effluent water. Aroclor 1242, the product formerly sold for use in capacitors, is shown ar the top. The Aroclor 1016 which was coated on the sell is shown next, followed by the PCBs leached from ii--. soils, and finally a less chlorinated member of the Aroclor seriesr Aroclor 1221, which was used as a standard for quantitation. The number above eav. peak indicates the dominant chlorobiphenyl in tf\t ?eak. A comparison of the Aroclor 1242 and At o * 016 chromatograms illustrates the reduction of . a penta and higher chlorobiphenyls achieved in thi ufacture of Aroclor 1016. 9 NPC00016240 207926  FIGURE 2. PCB ELECTRON CAPTURE GAS CHROMATOGRAMS 91 NpC 0 0 0 l 6 2 4 1 207927 The isomer distribution of the PCEs in the effluent water is the result of differences ir. the utsr solubility and adsorption characteristic: .: the isomers in Aroclor 1016. It is evident :V - onlv che less chlorinated, more biodegradable PC::. UftflD and FOCHT (1973a,b), TUCKER (1972), similar -.'zzlcr 1221, were leached from the soil. A deprecation rate for Aroclor 1221 of 73 t 211 has been observed in semi-continuous activated sludge tests at feed levels of 1 and 5 mgs/24 hours, TUCKER (1972). Conclusions The results of this study clearly demonstrate that PCBs are not readily leached from soil by percolating water. In the worst case, less than 0.054 of the total Aroclor 1016 available (25,000 ppm) was leached from the soil during the entire four-month duration of these experiments. During this period of time approximately 50-100 liters of water were passed through the three soil columns, an amount of water roughly equivalent to 50-100 ft. of rainfall, assuming no run off. The ease of leaching Aroclor 1016 from the different types of soils was in the following order: Norfolk Sandy Loan>Ray Silty Loam>Drummer Silty Clay Loam. Additionally, it was observed that only the less chlor inated, mre degradable homologs were leached from the soils. The results of this study support the conclusion drawn by the Michigan Water Resources Commission that land fills are only a minor source of PCB environmental contamination, HESSE (1971). Acknowledgements The authors wish to thank Dr. W. A. Darlington for pro viding the soils and his valuable assistance through out the study: References AHMED, M. and FOCHT, D. D.: Bull, of Environ. Contain. Toxicol. 10, 70 (1973a). 92 NPC00016242 * 207928 AHMED, M. ani F i i : . ! ' , D. D. : Can. J. Microbiol. 19, 47 (1973b). 6ESSER, H. D. e : (1971). Analytical Letters 12, 883 ~ HAQUE, R. et a'. :.r.viron. Sci. and Tech. 8 , 139 (1974). HESSE, J. L . : Commission FCI \r.ry of the Michigan Kater Resources -ring Efforts (1971). PCBs In the ; tion Service Virginia 22111 :E'<T : National Technical Informa .Apartment of Commerce, Springfield, ' ~:.A-71 *10419. TUCKER, E. S.: Monsanto Report, Assessment of the Biological Persistence of PCBs, presented to U.S. Government Inter -:par;mental Task Force on PCBs, Washington, . y 15 , 1972. 93 NPC00016243 207929