Environ. Sci. Technol. 1902, 16, 479-482
(10) Haag, W. R. In “Water Chlorination: Environmental Impact and Health Effects”;Jolley, R. L., Gorchev, H., Hamilton, D. Heyward, Eds.; Vol. 3, Ann Arbor Science: Ann Arbor, MI, 1979; Vol. 3, pp 193-201. (11) Trofe, W. T.; Inman, G. W.; Johnson, J. D. Environ. Sei.
(4) Luong, T. V.; Peters, C. J.; Young, R. J.; Perry, R. Environ. Technol. Lett. 1980, 1 , 299-310.
“Analysisof Raw, Potable and Waste Waters”;Department of the Environment: UK, BMSO, 1972,91-5. Palin, A. T. J. Inst. Water Eng. 1974,28, 139-154. Weil, I.; Morris, J. C. J. Am. Chem. SOC.1949, 71, 1664. Farkas, L.; Lewin, M.; Bloch, R. J. Am. Chem. SOC.1949, 71, 1988. (9) Morris, J. C. In “Principles and Applications of Water Chemistry”;Wiley: New York, 1967; pp 23-51.
Technol. 1980,15, 544-549. Received for review April 21,1981. Revised manuscript received December 28, 1981. Accepted February 9, 1982.
Halocarbons as Tracer Substances in Studies of the Distribution Patterns of Chlorinated Waters in Coastal Areas Ellsabet Fogelqvlst, Bjorn Josefsson, and Claes Roos Department of Analytical and Marine Chemistry, Chalmers University of Technology, University of Goteborg, S-412 96 Gijteborg, Sweden
Coastal and open seawater samples were examined with respect to halocarbons originating from different chlorination processes and natural sources. Chloroform from the bleaching of pulp and bromoform from the chlorination of seawater in power plants were used as tracer substances to establish the movement of the effluent plumes. The analytical method was based on pentane extraction of 100-mL samples, followed by glass capillary gas chromatography with electron-capture detection. The method is simple and fast, permitting large areas to be monitored during a short period of time when stable meteorological conditions are prevailing.
Introduction Chlorination is performed for different purposes such as the treatment of drinking and sewage waters, the bleaching of pulp, and the prevention of bioactivity in power-plant cooling systems. In Sweden the paper and pulp industry, the largest consumer of chlorine, uses about 300000 tons of chlorine a year (I). Electric power plants in coastal regions using seawater in the cooling-water systems are also large consumers of chlorine. The chlorination of the water prior to passage through the power plant is necessary to prevent settling of fouling organisms, e.g., barnacles and mussels. The discharges of chlorinated water in both of these applications are very large, in the range of 1-100 m3/s. These sources will then be large contributors of halogenated organic byproducts released in the marine environment. Chloroorganics,determined as total extractable organic chlorine, have been used by Ahnoff et al. for identifying discharges into a river system (2). A monitoring program was carried out in the river Rhine and several Dutch surface waters to determine the presence of organic halogen (3). Josefsson and Nyquist (4) used lignin sulfonates as tracers to follow the dispersion and flow direction of sulfite pulp mill effluents in coastal waters. That technique is, however, restricted to pulp mills using sulfite processing. The purpose of this work was to establish the movement of the effluent plumes from a pulp mill and a nuclear power plant in the same coastal region with the aid of different halogenated chemical-reaction products as tracers. Moreover, some other reference areas were investigated for purposes of comparison. The trihalomethanes produced during chlorination are particularly suitable as tracer substances since they may 0013-936X/82/0916-0479$01.25/0
be determined at very low concentration levels. Large amounts of chloroform are produced upon bleaching with chlorine, a process where fresh water is normally utilized (5). When bromide is present in the water, as in the case of seawater (65 mg Br-/L), brominated compounds, e.g., bromoform, are produced via the oxidation of bromide to bromine (6,7). Since the coastal power plants use seawater for cooling, they discharge bromoform. Therefore, it should be possible to distinguish between the two different kinds of effluents. The analytical method employed should be specific, rapid, and sensitive so that a large number of samples may be processed quickly, thus permitting coverage of a large area of water at a time. The limiting factor would then be the time spent collecting the water samples. Glass capillary column gas chromatography with electron-capture detection and on-column injection was the method of choice (5). The technique has been used to determine very low levels of trihalomethanes (0.1 ng/L) by on-column injection of large volumes of pentane extracts (Fogelqvist et al. (8)).
Experimental Section Sampling and Extraction Procedure. The water was sampled by using TPN-water samplers (Hydro Bios, Kiel, FRG). One to five milliliters of pentane (p. a. Merck) was added to 100 mL of water in a volumetric flask. The flask was shaken manually for 5 min. The pentane contained 5-1OOpg/pL of bromotrichloromethane, CBrC13 (p.a. Eastman), which was used as a gas chromatographic internal standard to control the injected amount of pentane. Glass Capillary Gas Chromatography. Two different gas chromatographic systems were used. The early investigations were carried out with a Perkin-Elmer 3920 gas chromatograph equipped with a split injector, glass capillary column, and a 63Nielectron-capture detector. Later on, a Carlo Erba Fractovap 4160 gas chromatograph with an on-column injector was used. Glass capillary columns were prepared according to the procedure described by Grob et al. (9). Normally, a 30-m glass capillary column with an inside diameter of 0.3 mm, coated with SE-52 on a BaC03 layer was used. The separations were performed isothermally at 40 OC with hydrogen as a carrier gas (50 cm/s). The injections of 10 pL of pentane extract were performed directly on-column within 5 s. The injector was air cooled. To avoid phase stripping, the first coils were washed clean with respect to stationary phase. The detector temperature was 275 OC, and argon with 5%
0 1982 American Chemical Society
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between 10 and 20 m, to minimize the effects on the brackish surface water. The vertical profile is shown in Figure 3. The highest chloroform concentration in the sea was found to be 9 pg/L. At the station marked with a star, for chloroform the maximum was found at a 15-m depth. The wastewater was distributed at depths between 13 and 18 m. There was no pronounced vertical mixing
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Figure 4. Bromoform distributlon outslde the power station illustrated wRh Isopleths showing the maximum concentration (pglL) at each sampling station. This appeared at the surface near the outlet and when moving away from the outlet gradually down to 6 m (date: July 11, 1979).
of the water masses on the sampling occasion. The distribution in the north-south direction is a result of the currents normally prevailing in this area along the Swedish coast. Above the pycnocline the northerly Baltic current with brackish water transports the injected wastewater. When the sampling took place, the current velocity was 700 m/h. Below the pycnocline a southerly current with Atlantic high saline water distributes parts of the wastewater in the southerly direction. In the pycnocline the currents were irregular with respect to velocity and direction. Two other coastal areas, one a t the Idefjord at the Norwegian border and one at the Swedish coast of the Gulf of Bothnia, were also investigated. Iri the Idefjord there is a sulfite pulp mill discharging bleaching effluents. The concentration of chloroform was in the range of 0.5-5.0 pg/L, and the distribution pattern coincided.with that of lignin sulfonates reported earlier (4). At the Ornskoldsvik site in the Gulf of Bothnia, the concentration gradient was typical for surface-water disposal of a bleaching effluent. In this area a remarkably high concentration of tetrachloroethylene, up to 100 pg/L, was found. The distribution pattern was quite different from that of chloroform, which indicates another source of this pollutant. Distribution of Chlorinated Seawater Discharged into the Sea. A nuclear power plant, which is located near the pulp mill discussed earlier (Figure 2), uses seawater for cooling purposes at a rate of 80 m3/s. Sodium hypochlorite is added to yield a maximum of 1.5 ppm of chlorine in the cooling water. The residual chlorine was lower than 0.1 ppm in the receiving water. The dosing is continuously carried out from April to November every year. The bromoform produced was used as a tracer substance. Environ. Sci. Technoi., Vol. 16, No. 8, 1982
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in the treatment of power-plant coolant waters, are the main sources of these compounds. Lower amounts of bromoform are of biological origin and may in certain cases interfere with the measurements. Effluents from the two different chlorination processes could easily be distinguished when discharged in adjacent marine coastal waters. The analytical method applied shows the need for sensitivity, speed, and specificity in monitoring large sea areas to establish the hydraulic conditions in a short period of time. The time aspect is important since meteorological conditions may quickly change the physical conditions in the recipient. Alternative added synthetic tracers such as radioactive bromine or Rhodamine WT have also been used. However, these tracers can be examined only at limited distances from the outlet sites.
Acknowledgments I I
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We thank Goran Eklund for valuable collaboration. The kind assistance from the personnel at the electric power plant and the pulp mill is gratefully acknowledged.
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800 depih(m) Flgure 8. Bromoform depth profiles at three stations west of Spltsbergen in August and September 1980.
Conservative Properties of the Tracers. The behavior of chloroform and bromoform in seawater have been discussed by Helz and Hsu (14). In our investigation the chloroform in the bleachery effluent is injected at such a depth that the volatilization into the atmosphere plays a minor role. Thus, dilution is the major process controlling the concentration pattern of chloroform in the plume. In the case of effluent containing bromoform that is discharged at the surface, there will be a transfer process to the atmosphere by evaporation. Some calculations based on a work by Liss and Slater (15) tentatively estimate the bromoform half-time decay to be 85 h at a 5-m depth in well-mixed coastal waters (14). In our case the vertical mixing is limited. Although bromoform loss to the atmosphere is occurring, the dilution effect seems to be the main process. Thus, the bromoform can still be considered as a useful plume tracer substance. The biological degradation processes of bromoform in the sea are still not clear.
Concluding Remarks The use of chloroform and bromoform as tracer substances to establish the distribution pattern of chlorinated effluents in the sea is very useful. Two chlorination processes, one used in the bleaching of pulp and the other used
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Literature Cited (1) Sjoqvist,A. "Chlorination of water. Chemical and biological aspects"; National Swedish Environment Protection Board, Report PM 1100 Solna, Sweden, 1979. (2) Ahnoff, M.; Josefsson, B.; Lunde, G.; Andersson, G. Water Res. 1979,13, 1233-1237. (3) Wegman, R. C. C.; Greve, P. A. Sci. Total Environ. 1977, 7, 235-245. (4) Josefsson, B.; Nyquist, G. Ambio 1976, 5, 183-187. (5) Eklund, G.; Josefsson, B.; Roos, C. J. High Resolut. Chromatogr. Commun. 1978,1, 34-40. (6) Bean, R. M.; Riley, R. G.; Ryan, P. W. In "Water Chlorination"; Jolley, R. L., Gorchev, H., Hamilton, D. H., Eds.; Ann Arbor Science: Ann Arbor, MI, 1978; Vol. 2, Chapter 17. (7) Helz, G. R.; Hsu, R. Y.; Block, R. M. In "Ozone/Chlorine Dioxide Oxidation Products of Organic Materials"; Rice, R. G., Cotruvo, J. A., Eds.; Ozone Press: Cleveland, OH, 1978; pp 68-76. (8) Wgelqvist, E.; Josefsson, B.; Larsson, M., unpublished data. (9) Grob, K., Jr.; Grob, G.; Grob, K. J. High Resolut. Chromatogr. Commun. 1978, 1, 149-155. (10) Eklund, G.; Fogelqvist, E.; Josefsson, B.; Roos, C. "Distribution of bromoform in sea water"; Proceedings, European Symposium on Micropollutanb in Water, Berlin, 1979. (11) Dyrssen, D.; Fogelqvist, E. Oceanol. Acta 1981,4,313-317. (12) Moore, R. E. Acc. Chem. Res. 1977,10, 40-47. (13) Burreson, Y.; Moore, R. E.; Roller, P. P. J . Agric. Food Chem. 1976,24,856-861. (14) Helz, G. R.; Hsu, R. Y. Limnol. Oceanogr. 1978,23,858-869. (15) Liss, P. S.; Slater, P. G. Nature (London) 1974, 247, 181-184.
Received for review October 26,1981. Accepted March 15,1982. This investigation was supported by the Research Committee of the National Swedish Environment Protection Board and the Swedish National Research Council.
