Document dzkapOmXEZjX3bpbr2Em3EpQ

References " Darby, R. T.( Kaplnn. H , Appl. Microbiol.. 16, 900 (1PG8). Dean, K. C., ChimiL'rcn. C. J.. Valdez. K, G.. "Innovations in RecydinR Automotive Scrap." Arm. Nteetinc, Institute of Scrap Iron and St eel Inc.. Wiishinetnn. I ).C.. -January 1.0-18. 1972. Dean, K. C.. Mulmncy, L. R., Valdez, E. G.. manuscript in prep aration. 19TJ. Larsen, F. N.t Sixth International Gel Permeation Chromatogra phy Seminar, pp 11-129. Miami. Fla.. October 19G8. Mahoney, L. R., Weiner, S. A., unpublished data, 1972. 'Sounds J. H.. Frisch K. C.. "Polyurethane,. Chemist rv and Technology. Part il Technology. (im-riaenrc SJTM, v i N.Y., 1%7. ' u,k- Warner, A. J.. Parker, C. H.. Runm. R,, '`Solid Wnsle Manure ment of Plastics,'' p A.78. Project 14-10.2. Dtile|| 0(,rf r> ' hurrJ son, Haznrdvillc, Knlicld, Conn. (1970,i|. Warner, A. J., Parker, C. H., Baum. B., ibid., p A-g( (1970b) Received for review December 20, 1972. Accepted September 7. 1973. Aqueous Solubility, Adsorption, and Vapor Behavior of Polychlorinated Biphenyl Arocior 1254 Rizwartul Haque,' David W. Schmedding, and Virgil H. Freed Department of Agricultural Chemistry and Environmental Health Sciences Center, Oregon State University, Corvallis, Ore. 97331 The water solubility, adsorption from aqueous solution, and the vapor behavior of the polychlorinated biphenyl Arocior 1254 have been determined. The aqueous solubili ty of Arocior 1254 has been found to be ~ 56 ppb. The ex tent of adsorption of the PCB's is highly dependent on the nature of the adsorbent. Del Monte sand adsorbs very lit tle as compared to a Woodburn soil. The vapor loss of Arocior is significant from the sand but negligible from the soil. The vapor loss increases with increasing tempera ture. In general, the isomers containing fewer chlorine atoms show greater loss as compared to other isomers hav ing more chlorine atoms. The occurrence of polychlorinated biphenyls (PCB's) in the environment and their consequence on environmental quality have been well emphasised in recent years (Nelon, 1972; Gustafson, 1970, 1972- Peakall and I.incer, 1970). Data describing PCB residues in water and animal tissue and their toxicological effects are accumulating at a rapid rate (Nelson, 1972; Gustafson, 1972). However, little ia known about the mechanism of transport of PCB's in the environment. The question of how PCB's are trans ported in the biosphere still remains. To answer this, one must know the basic properties of PCB's. In the present manuscript, we shall describe the behavior of the PCB, Arocior 1254, in some laboratory water, soil, and air sys tems. The chemical properties discussed are the water solubility, vapor loss, and adsorption. Experimental 1 . The PCB, Arocior 1254, was a sample from Monsanto Chemical Co. nnd was used without further purification. The clay, sand, silica gel, and soil samples used in this study and their sources are given in Table I. All adsor bents were used as received, aside from screening (50/80 mesh), except Ottawa send (20/30 mesh), which was used as received. Woodburn soil was determined to have 3.17c organic matter and Ui.27o clays. The distilled water used 1 To whom correspondence ahouldbfc Sctdresucd. throughout the studies was extracted with hexane and boiled for 1 hr to remove the residual hexane. This proce dure was necessary to be sure test water was free from dissolved organic materials. The procedure for each exper iment is outlined as follows: Solubility Studies. Approximately 5 grams of the chemical was placed in a large Erlenmeyer flask (C-iiter), stoppered, and equilibrated with water. To prevent d>spersion of PCB. the sample was slowly stirred with a mag netic stirrer. To eliminate heat transfer, the stirrer and flask were separated by a ^-in. polystyrene sheet. An ali quot of aqueous sample was removed, centrifuged at 3000 rpm for 10 min, extracted with hexane, and analyzed lor the PCB. The analysis was carried out at 1-weck intervals and was continued until it was determined that the con centration had reached the saturation point. A typical gas-liquid chromatogram of a standard and a water extract is shown in Figure 1. The individual peaks in the chromatogram corresponding to different numbers of chlorine substitutions were identified by mass spec trometry. The distribution of chlorine components in the mixture was established initially by microcouiotnetric gas chromatography. The gas chromatogram shape changed owing to the differential rates of solubilization of the vari- Table 1. Sources of Materials Under Investigation Surface Source lllite clay Kaolin I tc clay Montmorlllonite clay Silica gel Del Monte sand Woodburn soil Ottawa sand lllite #35--FitHi an, III., Wards Natural Science Establishment Inc., Roch. ester, N.Y. Kaollnite f4--Oneal Pit, Macon. Go., Wards Natural Science Establishment Inc.. Rochester. N.Y. Montmorillonile 26--Clay Spur, Wyo., Wards Natural Science Establishment Inc., Rochester. N.Y. Silica Gel, Powder - 3405, J. T. Baker Chemical Co., Phliiipsbutg. N.J. Del Monte Sand, EL-30, Del Monle Properties Co., San Francisco, Calif. Woodburn Silt Loam, 0-4 In., Hyslop Farm, Corvallis, Ore. Sclontilic Supplies Co., Seattle, Wash. Volume A. Number 2, February 1974 139 DSW 0 2 6 4 7 2 STLCOPCB4010433 al materials. The amount of chemical adsorbed, i, was calculated by the formula: x - V(C, - C,) U) where V is the volume of the adsorbate. C2 and C1 are the original and final concentrations of adsorbate (ppb). Vapor Loss Studies. Two different kinds of investiga- tions were carried out to observe the vapor loss of PCB. In one experiment the loss was studied from Aroclor 1254 it- lelf, whereas in the other case the vapor loss was moni tored from Ottawa sand and Woodburn soil. In the first et a known quantity (~0.6 gram) of the chemical was placed in planchets (exposed area 5.07 cm1) and the vapor loss was monitored gravimetrically as a function of time. The experiments were carried out in duplicates and at two different temperatures (26 and 60C). The second experi ment was performed as follows: Sand and the soil surfaces were treated with the PCB. An ether solution of Aroclor 1254 of known concentration was mixed with sand or soil and dried on a rotary evapo Arector If54 fiondo'4 ond maei chrom9tc>9rophd *n 9 7% PC-H,*N*HPW. 6' 04J' ID HemUM iui . at FOO* C . ictrpA capture detector. Figure 1. Typical gas chromatograms of slandard and a water extract Aroclor 1254 in hexane rator for 2.5 hr. Ottawa sand (130 grams) containing PCB was placed in petri dishes. Entire samples were taken at 0-, 1- and 4-week intervals and extracted in Soxhlet ex tractors. The chemical was extracted with 250 ml of acetone for 24 hr and the volume of acetone was reduced to 100 ml bv evaporating under nitrogen stream, partitioned into hexane ous isomers before equilibrium. The envelope was divided by adding 200 ml of 2% Na2SO< and extracted three times into 4, 5, C, and 7 chlorine components bv drawing a line with hexane. The sample was concentrated and analyzed perpendicular to the baseline at the minimum of the trace on a Tracor gas chromatograph equipped with NitJ do- between various chlorinated portions. Further division tector. was not attempted owing to insufficient separation of indi Similar experiments were done under wet conditions by vidual isomers. Since many of the peaks were not sharp, adding approximately 30 ml of water every day. The ex the cut and weigh method was used to determine peak periments with soil were carried out by placing (25 grams) areas. Isomers having different numbers of chlorine atoms of Woodburn silt loam containing 10 ppm of Aroclor 1254 possess varying electron-capture detector response, thus a in 130-S Lilly cups. The cups were equipped with an alu correction was needed to quantilize the data. The differ minum support wrapped with 2-Kiniwipes (Nu. 3415) and ential response for various chlorine containing isomers was placed in the groove of the cup. The Kimwipes acted as a referenced relative to p.p'-DDE. The final concentration wick for the wet soil loss study. A filter paper (No. 42) of the PCB was determined by comparing with a known was placed on the Kimwipe wick to act as a soil barrier. standard. The samples were taken at 0-, 1-, 2-, 3-, and 4-week inter Adsorption Studies. The adsorption studies were car vals and the PCB was extracted with acetone using the ried out by equilibrating a saturated aqueous solution of procedure described earlier in this paper. Similar experi PCB with a known amount of the adsorbent material. The ments were performed under wet eonditions by adding saturated aqueous solution was previously equilibrated as ~50 ml of water at 48-hr intervals through a small funnel described for approximately 6'A months. Since the solu inserted in the cup. All the above experiments were car bility of Aroclor 1254 is in the ppb ange, the equilibrium ried out in duplicate at room temperature (2GC). experiments were performed with the concentration of PCB constant and the amount of adsorbent material var Results and Discussion ied rather than vice versa. A known quantity of adsorbent The equilibration of Aroclor 1254 in water was achieved material was weighed in a 250-ml centrifuge bottle, and a in approximately 2 months, the concentration at this saturated solution of the PCB (125 ml) was added and point was approximately equal to that at 6 months. It was kept on a shaker for 24 hr. Earlier studies showed that expected that the total solubilization process would be a thin period of time was sufficient to reach equilibrium for slow one, although it takes only a week to nehirve a major the adsorption of other pesticides on surfaces from aque part of the equilibrium. The total solubility of Aroclor ous solution (Haque and Sexton, 1968; Haque and Cosh _1254 was ~56 ppb. This value is within the rangc'rc- ow, 1971). The samples were then centrifuged at 3000 ported for many chlorinated hydrocarbon insecticides rpm, and 100 ml of the supernatant liquid were extracted (DDT-tvpe compounds) having similar structure (Bow with three 15-ml portions of hexane. man et al., 1900; Bigger ct al., 1907; (iunther et al., 1907). The extract was blown down to approximately 3 ml However, it is significantly lower than the values reported under a nitrogen si renin and the sample mode up to 5 ml by Zitko (1971), who obtained solubilities in the range of in a volumetric 11 ask. The concentration of PCB remain 0.3-3 ppm in "fresh water." These high values may be due ing in solution was determined on an Aerograph 550 gas to the presence of foreign materials in the "Ircsh water." chromatograph, equipped with an electron capture detec From the intensities of various peaks in the gas chro tor, The adsorption of Aroclor 1254 on the surface of the matogram, it may be said thnt the water solubility of container was accounted for by running a blank through PCB isomers in general decreases with increasing chlorine the analysis. We have determined the adsorption of Aro atoms. clor 1251 on surfaces !>v taking into account the sum of all The percent decrease in the roneentral inn of Aroclor the gas chromatographic peaks. No attempt was made to ',|l(1254 by tire addition of increasing amounts ol adsorbent determine the adsorption ol each constituent on individu- I ^material is shown in Figure 2. As expected, sand and sili- 140 Environmental Science & Technology DSW 0 2 6 4 7 3 I ; : i ' j j STLCOPCB4010434 Figure 2. Percent decrease in the concentration of Aroclor 1254 by the addition ot increasing amounts ol adsorbent. Original concentration ol Aroclor 1254, 56 ppb ca gd adsorb very little of the chemical whereas illite clay and Woodburn soil showed greater adsorption. The ad sorption behavior of montmorillonite and kaolinite clays was intermediate between (hose extremes. The high-ad sorbing capacity of Woodburn soil is tentatively attrib uted to the presence of organic matter. The adsorption equilibrium of PCB on illite and Woodburn soil was treat ed by a Freundlich-typc isotherm Equation 2: Figure 3. Freundlich Isotherm showing adsorption of Aroclor 1254 on illite clay and Woodburn soil (C In ppb ana x/m in ng/g) -m - KC.1 " (2) where K and n are constants and m the mass of the adsor bent in grams. A typical Freundlich plot is shown in Fig ure 3. The values of K and n for illite clay and for Wood burn soil are G3.1 and 1.1 and 26.3 and 0.81, respectively. The Freundlich-typc isotherm shown in Figure 3 suggests a physical-type adsorption. The Freundlich isotherm for other surfaces is not shown because of their extremely low adsorption capacity. The loss of Aroclor 1254 from itself is shown in Figure 4. Although the loss of the chemical is rather small at 26C, it is substantial at G0C. It is interesting to note that the weight los&xhangtcis Jinea'r as a runcuon~oTTifheTWathemalically, such a behavior is characteTisiic dr diffusion in a plane sheet (Crank, 19G7), and could be expressed as in Equation 3: Massloss(r)" AF ( (3) where A is the exposed area, t the time, and F the flux defined by Equation 4: where 1) is the diffusion coefficient, (cic/Hx) is the concen tration gradient, and L the thickness ol the sheet. Since it is not possible lo estimate the concentration gradient froin the available data, it is difficult to calculate I). However, from the slope of the line (Figure 4), we ran calculate the flux. The calculated value of the flux has been found to be 2.0 x 10 6 gram day 1 cm-2 at 2GC and 8,6 10"s gram day 1 cm "2 at 60C. The loss of PCB from a sand surface is shown in Figure 6. As expected, the higher chlorine-containing isomers show the least los* and vice versa. This is mainly due to the fact that the vapor pressure for PCB isomers decreases with increasing number of chlorine atoms. Vapor loss under wet conditions was similar and comparable in mag nitude. Similar experiments dealing wit It the Woodburn Figure 5. Loss of Aroclor 1254 from on Ottawa sand Volume 8. Number 2. February 1974 141 DSW 0 2 6 4 ? ^ STLCOPCB4010435 soik showed thnl vapor loss of Aroclor 1254 from the soil surface was negligible. The high loss Irnm the sand as tompared to the soil nia.v be attributed to the marked tiifIcrence in the absorbing capacity of these two surfaces. The vapor loss behavior of l'CH from sand and soil surlac/ea is qualitatively similar to DDT (Cliath and Spencer, 1912; GUenzi and Beard, 1970). The findings of this paper give a qualitative picture of the behavior of the I'CH Aroclor 1201 in water, soil, and air. It is difficult to extend these findings directly to the field conditions. There is always a danger of drawing erro neous conclusions. However, some speculations about the environmental significance of the work could be made. In general, once l'C.H is introduced in the environment, the isomers Will txfTraVis ported in air, soil, water, and biota. The concentration in each phase will highly depend upon the partition coefficients. The water solubility will deter mine the distribution in water. It appears that I'CH in ppb range could be transported in water. The environ mental contamination of water will highly depend upon the number of chlorine atoms present in the isomer. The lower chlorine-containing isomers will show higher con centration in water and vice versa. The concentration of PCI3 in water will be reduced whenever the water comes in contact with a solid surface or particulate matter. The -T*rtTlrTTpM~in the eoncenirfliuin nf I'CH ill water will de- pentfupon the surface characteristics. Such properties as the surlacc area, organic content of the material, nature of the surface (clay, sand), and pH of the medium will greatly influence the adsorption. The transport of HCB in air will be governed by temperature, vapor pressure, and the surroundings of the chemical. Sig nificant amounts of I'CH could be transported in air at higher temperatures if I'CH is present in the environment where it is loosely bound or adsorbed to a surface. The loss could also be significant if PCH is evaporating from its own surface, especially at higher temperatures. The number of chlorine atoms present in the particular f'CB isomer will also influence the loss to a great extent. The larger the number of chlorine atoms present in the isomer, the smaller the loss. However if I'CB, on the other hand, is bound strongly to a surface, the vapor loss will be much smaller. In general, the environmental contamination and exposure of I'CH to living species will be functions of the surrounding temperature, moisture, surface, and so forth. The findings of this paper may be summarized as fol lows: The solubility of Aroclor 1254 at room temperature is ~56 ppb and, although the solubilization is a slow pro cess, the bulk of the process is achieved very rapidly. Aro clor 1254 is readily adsorbed from aqueous solution onto available surfaces. The amount of chemical adsorbed de pends upon the nature of the surface. A sand sqtfacfi-with few sites adsorbs relatively little, whereas a so:! surface with high clay and organic content adsorbs a much larger amount. The vapor loss of Aroclor 1254 from Its own sur face depends on the area exposed and the temperature. At room temperature it is small, but by approximated dou bling the temperature, loss is enhanced by a (actor of 40. The vapor loss from a sand surface is significant whereas from a more tightly bound situation on a soil surface, it is extremely small. The generally more volatile lower chlo rine isomers show a greater loss than those of higher chlorine content. Acknowledgment We thank Susan E. Randall for her technical assistance and Donald A. Griffin fur his help in identifying various isomers via mass spectrometry. Literature Cited Bigger, J, W., Dutt, G. R., Riggs, R. L., Hull Environ. Contam. Toxicol.. 2,90(1967). Bowman, M. C., Acree, F.. Corbett, M. K., J. Agr. Food Chem., 8, 40G (I960). Cliath. M. M.. Spencer, W. F., Environ. Sci. Techno!., 6, 910 (1972). Crank, )., "The Mathematics of Diffusion." Oxford at the Clar endon Press. U.K.. 19C7. Guenzi. W. D., Beard. W. E., Soil Sci. Soc. Amcr. fVor., 34, 443 (1970). Gunther, F. A., Westlake, W. E., Jaglen, P. S., Res. Rev., 20, 1 (19G7). Gustafson. C. G., Ed., 1'roc. Rymp. on PCB's--Still Prevalent- Still Persistent. 164th American Chemical Society Meeting, New York, N.Y., September. 1972. Gustafson. C. G.. Environ. Set and Tech.. 4, 814 (1970). Haque. R., Coshow, W. R., Environ. Sci. & Techno!., 5, 139 (1971). Haque, R.. Sexton. R., J Colloid Intcrfac. Sci., tl, 818 (1968). Nelson, N.. Chairman, panel on "Hazardous Substances. Poly chlorinated Biphenyls -- Environment a! Impact," Env. Res., 3, 249(1972). ' Peakatl, D. IV. l.incer, J. 1, , Hiosci.. 20, 958 (1970). Zitko, V,, Hull Environ. Contain. Toxicol., 5, 279 (1971). Received for review January 29. 1971. Accepted October ,1. I9~'i The research described here is supported by l.i.S. Tubhc Health Service Grant No. ES-OOO-lO. 142 Environmental Science A Technology DSW 026475