Environ. Scl. Technol. 1988, 22, 1156-1 160
Photochemical Formation of H202in Natural Waters Exposed to Sunlight William J. Cooper,**+Rod 0. Zlka,* Robert G. Petasne,t and John M. C. Plane' Drinking Water Research Center, Florida International University, Miami, Florida 33199,and Marine and Atmospheric Chemistry, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, Florida 33149
Hydrogen peroxide is formed in most natural waters when they are exposed to sunlight. The rate at which H202 accumulates is related to the concentration of light-absorbing (>295 nm) organic substances in these waters. The photochemical accumulation rate of H202 in sunlight has been measured for several surface waters and oundwaters and was found to be 2.7 X lo-' to 48 X 10-Fmol L-' h-l, in waters ranging from 0.53 to 18 mg L-l dissolved organic respectively. These rates were determined carbon (DOC), in midday sunlight, 0.4 W m-2 (295-385 nm), latitude 24.3' N. Apparent quantum yields of H202 have been determined for natural waters at different wavelengths. These quantum yields decreased with increasing wavelength, from in the near-ultraviolet to lo* in the visible spectral range. The quantum yields have been used in a photochemical model to calculate H202accumulation rates of natural water samples. Model calculations agree with Hz02 accumulation rates obtained from exposing three different water samples to sunlight. W
Introduction Recently there has been increasing interest in reactive species in natural waters that result from the interaction of sunlight and light-absorbing substances (1). These transients may play an important role in redox reactions in natural water systems (2-4) and may also be important in the environmental fate of organic compounds. One such transient, hydrogen peroxide (H202),has been shown to form in freshwater (5-9), estuarine (IO),and marine environments (11-16) (see Table I). It has been suggested that the H202accumulation rate, i.e., the net formation rate in natural waters where both formation and destruction occur simultaneously, is correlated with the concentration of naturally occurring humic substances in surface waters and groundwaters (9). Hydrogen peroxide appears to result, at least in part, from the disproportionation of superoxide, 0;- (9,17-19). Superoxide is formed by the reduction of oxygen in natural waters where the light-absorbing substances either generate free electrons by photoionization or reduce oxygen by energy transfer from the excited state. It is also possible is formed in natural waters by a one-electron that 02'transfer from reduced metals (2) or heterogeneous photocatalyzed reactions [e.g., Ti02 (2U)]. Hydrogen peroxide in natural waters may be a source of free radicals (21) and as such may be of major significance in indirect photolytic processes in natural waters (22). It is also possible that H202may react directly with pollutants (22-27) or with a wide variety of naturally occurring dissolved or particulate constituents. We report the results of an investigation into the phoin samples of both surface tochemical formation of H202 waters and groundwaters. Groundwater samples were used because they had not been naturally exposed to sunlight and were a convenient source of waters with a wide variation in dissolved organic carbon. Recently it has been +FloridaInternational University. University of Miami. 1156
Environ. Sci. Technol., Vol. 22, No. 10, 1988
Table I. Reported HzOzConcentrations in Surface Waters
[HZ0,], X107 mol L-l natural after levels irradiation
water source freshwater Volga River Area, Russia reservoir, Russia southeastern U S . California groundwater, U.S. agricultural waters irrigaiion runoff sewage raw ponds, U S . seawater Texas coastal waters North Atlantic Biscayne Bay-Florida Coast Gulf of Mexico coastal offshore Bahama bank Peru coast and offshore estuarine Chesapeake Bay
13-32 7-13 0.9-3.2
-a
ref
18-26 6-70 19-26 0.06-100
5 6,7 9 8 9
-
18-68 23-53
8 8
-
25 125-325
8 8
-
O* * -
-
0.08-0.7
-
11 12 14 2 16 16 14 15
0.03-17 0.54-0.75
-
10 10
0.14-1.7
-
0.35-1.6
0.8-2.1 1.2-1.4 1.0-2.4 0.9-1.4 0.6-1.9
-
(-) indicates data not reported.
-
(*) indicates detection limit
of 0.5.
reported that H202 may be present in some groundwaters (28); however, its exact source is not known but could not be photochemical. Accumulation rates of H202were determined by exposing the waters to sunlight. They were also determined in the laboratory for various narrow and broad wavelength regions of the solar spectrum. From the latter data and absorbance measurements apparent quantum quantum yields were calculated. These H202 yields are used in a photochemical model to calculate accumulation rates in several different waters and at several depths (26, 29).
Experimental Section Natural Water Characterization. Groundwaters and surface waters for this study were obtained from several sources throughout the United States. Samples were collected in glass bottles with Teflon-lined caps. The samples were refrigerated immediately upon receipt in the laboratory. Surface waters were filtered through a 0.45-pm filter prior to the experiments. Instrumentation. A Turner Designs fluorometer determinations; the ex(Model 10) was used for all H202 citation band was centered at 365 nm and the emission band at 490 nm. To achieve this, the instrument was equipped with the following filters, a Corning CS 3-72 for reference, a Corning CS 7-60 for excitation, and Turner 2A and 65A for emission. A near-UV lamp was used as an excitation source. A stirrer was incorporated in the sample compartment to achieve rapid uniform stirring and homogeneous solutions during reagent additions and measurement.
0013-936X/88/0922-1156$0 1.50/0
0 1988 American Chemical society
An Epply radiometer (Model TUVR) and integrator (Model 411) were used for the measurement of solar radiation. The radiometer was equipped with a visible light (>385 nm) cutoff. All absorption spectra were obtained by a HewlettPackard Model 8450A UV/visible spectrophotometer, employing 1-or 10-cm quartz cells. W avelength-dependent studies were performed with a Kratos-Schoeffel illumination system equipped with a YSI-Kettering Model 65A radiometer. A 1000-W Hg-Xe lamp followed by a Kratos monochromator Model GM-252 were used for single-wavelength studies. Bandwidths of 16.5 nm centered at 280.4, 296.7, 313.0, 334.1, 366.0, and 404.5 nm were used in these studies. A 1OOO-W continuous Xe lamp followed by water-cooled Corning glass filters was used for longer wavelength bands of visible light. The following long band-pass Corning filters were used: 0-52, 3-74, 3-72, 3-69, and 2-61. The 0.10% cutoffs were at 340, 400,445,515, and 600 nm, respectively. These experiments were conducted at room temperature, 25 f 1 "C. Chemicals. Hydrogen peroxide, 30%, was used as received (Baker analytical reagent grade) for H202solutions and was standardized by iodometric titration. Scopoletin and horseradish peroxidase (HRP) type I1 (EC 1.11.1.7) were obtained from Sigma Chemical Co. and used as received. Low residual organic water was used to prepare all buffers, scopoletin, and enzyme solutions for dilution of sample solutions and as a reference for absorption spectra of natural waters. The low residual organic water was prepared by slow redistillation, over potassium permanganate, of water obtained from a Millipore Super-Q water system. Analytical Methods. A fluorometric method for the determination of H20zwas used (28, 30). The method relates the concentration of Hz02to an enzyme-mediated depletion of scopoletin fluorescence. A 20-mL sample size was necessary for the Turner Designs fluorometer. To this sample was added 100 p L of 0.5 mol L-l, pH 7, of phosphate buffer with stirring and the base line recorded. A mol L-l of scopoletin precisely measured volume of 5 X solution (typically 40 pL) was added to the sample and the fluorometer set at 100% transmission. Next, an aliquot of a 10"' mol L-l horseradish peroxidase (20 mg/5 mL) solution in 0.01 mol L-l, pH 7.0, of phosphate buffer and 1X mol L-l of phenol was added (typically 20 pL). An immediate decrease in fluorescence indicated the presence of hydrogen peroxide. Because of high fluorescence backgrounds and high H202 concentrations in the waters with high total organic carbon, TOC (TOC >2 mg as C L-'), a 1:20 or 1:40 dilution of the sample with low residual organic water was necessary prior to analysis. Procedures. (A) H z 0 2Accumulation Rates. Sunlight reactions were carried out in 300-mL quartz roundbottom flasks sealed with 24/40 glass stoppers. Teflon sleeves were used to ensure a consistent seal. The flasks were inverted and suspended in air to minimize interference of the light path with the glass stoppers. Small aliquota were removed at regular intervals, the light flux was noted, and the sample was analyzed for H2OP To minimize the effect of back-reactions and temperature, H202accumulation rates were obtained from the initial slope of H202 concentration vs solar energy flux plots. These experimenta were conducted at ambient temperatures, 25-30 "C. (B) Apparent Quantum Yields. Apparent quantum yields, $A, were obtained by irradiating water samples in the laboratory and measuring the rate of H202production. The definition of $A in this case is the number of molecules
of H202formed per photon absorbed by the solution. (It is important to realize, that $A accounts for all processes contributing to the formation and destruction of H202in the natural water samples.) The water samples, contained in a 10-cm (30-cc) quartz cell, were irradiated with narrow bandwidth or broad bandwidth wavelength intervals. Hydrogen peroxide accumulation rates were obtained by using a numerical second-order fit of the data and taking the derivative at t = 0. Apparent quantum yields were calculated according to
where d[H202]/dtis the H202accumulation rate at the wavelength(s) of irradiation, Id is the photon flux (photons/unit area per time) through the irradiated cell at the is the fraction of light absame wavelength(s), 1sorbed by the water sample in the irradiation cell at the wavelength(s) of irradiation, and 1 is the path length of the quartz cell. Estimates of H202 accumulation rates and apparent quantum yields were found to be f10% when repeat observations were performed. The light flux at specific wavelengths was measured by the standard ferric oxalate adionometer (31). A Reinecke salt actinometer was used to determine the light flux with the long band-pass filters (32).
Results and Discussion The extent to which photochemical reactions occur in waters exposed to sunlight depends on several factors, namely the concentration of photoreactive materials, quantum yields, the attenuation of light with depth, and the intensity of incident solar radiation. Intermittent cloud cover, length of day, time of day, time of year, and latitude all introduce variability in energy flux to the surface of the earth. Sunlight-induced photochemical reaction rates may therefore fluctuate considerably, when reported with respect to time, if these variables are not accounted for during the experimentation. Our sunlight experiments were conducted on clear days during midday, 1000-1600 hours, and the solar radiation flux was determined as a function of the time of day. For the spectral region 295-385 nm, nearly constant fluxes of 0.38 and 0.45 (W m-2) were obtained for January and June, respectively. To convert to a time base in our calculations we use a value of 0.40 W mT2. Time-based accumulation rates of Ha02are summarized in Table XI. In general, H202accumulation rates correlated well with TOC and the amount of light absorbed by the water sample. Apparent quantum yields were determined for six different natural water samples (Table 111). In general, the apparent quantum yields decreased with increasing wavelength for all samples and showed remarkable similarities in all samples throughout the region 295-404 nm. These quantum-yield data were used in a photochemical model to calculate H202 accumulation rates in natural waters (29).Because the model specifies quantum yields at wavelengths not determined under our experimental conditions, it was necessary to interpolate between measurements at individual wavelengths (Table 111). To determine accumulation rates with depth, the model was modified somewhat. The basic differences are that the modified version uses wavelength-dependent quantum yields rather than a fixed quantum yield and calculates H202 accumulation rates at specific depths rather than an Environ. Sci. Technol., Vol. 22, No. 10, 1988
1157
Table 11. Chloride Ion, Dissolved Organic Carbon, and Hydrogen Peroxide Accumulation Rate in Groundwaters and Surface Waters (Assuming 0.4 W m") chloride ion, mg L-l
water sample groundwaters Tucson, A2 spring water, Coudersport, PA spring water, Sodus, NY well 18, Miami, FL Preston Well 5, Miami, FL well 23, Miami, FL Northwest Well 5, Miami, FL Northwest Well 1, Miami, FL surface waters (filtered) Chechesse River, SC VH Pont, Miami, FL VH Pond, Miami, FL Tamiami Canal, Miami, FL Combahee River, SC Newnans Lake, Gainesville, FL Peacock River, GA surface waters (unfiltered) VH Pond, Miami, FL Tamiami Canal, Miami, FL
dissolved organic carbon, mg L-l
HzOzaccumulation, X107 mol L-' h-l
0.22 0.53 0.93 2.9 6.2 10.3 13.2 17.6
0 2.7 0 5.9 16 17 48 46
8.3 16
24.2 761 9.4 165
2.2 6.9 8.1 12.4 14.7 11.6 17.8
38 44 24 74
14.0 24.2
6.9 12.4
14 27
7.4 0.55 17.4 19.1 47.5 40.0
ND' 29.0 19 040 14.0
ND
ND
"ND = not determined. Table 111. Absorbance and Quantum Yields of HzOaAccumulation for Six Watersa
-
wavelength, nm 297.5 300.5 302.5 305.0 307.5 310.0 312.5 315.0 317.5 320.0 323.1 330.0 340.0 350.0 360.0 370.0 380.0 390.0 400.0 410-440* 450-500* 525-600** 625-700**
spring water, Coudersport, PA (TOC = 0.53) Absorb @A
groundwater Preston Well 5, NW Well 5, Miami, FL Miami, FL (TOC = 6.2) (TOC = 13.2) @A Absorb @A Absorb
0.0178 0.0169 0.0160 0.0152 0.0144 0.0135 0.0128 0.0121 0.0114 0.0108 0.0102 0.0088 0.0075 0.0067 0.0061 0.0056 0.0052 0.0049 0.0045
8.8 8.4 7.9 7.5 7.0 6.5 6.0 6.1 6.2 6.4 6.6 7.0 6.5 5.4 4.2 3.3 2.8 2.2 1.5
0.167 0.162 0.157 0.152 0.148 0.143 0.139 0.134 0.131 0.127 0.122 0.112 0.098 0.086 0.074 0.063 0.054 0.045 0.038
6.2 6.1 5.9 5.8 5.6 5.5 5.3 5.2 5.2 5.1 5.0 4.8 4.2 3.5 2.7 2.2 2.0 1.9 1.7
ND ND ND ND
ND ND ND ND
ND ND ND ND
ND ND ND ND
"(*I = wavelengths every 10 nm.
(** ) =
0.283 0.271 0.260 0.250 , 0.239 0.230 0.220 0.212 0.203 0.195 0.185 0.165 0.139 0.116 0.096 0.079 0.064 0.052 0.029 0.029 0.0093 0.0028 0.00051
17 16 15 15 14 13 12 12 13 13 14 15 14 11
8.2 6.8 6.9 7.2 2.0 2.0 1.4 0.086 0.12
0.403 0.387 0.373 0.359 0.345 0.332 0.320 0.308 0.296 0.285 0.273 0.244 0.207 0.174 0.145 0.118 0.097 0.078 0.064
7.1 7.0 6.8 6.7 6.6 6.4 6.3 6.2 6.2 6.1 6.1 6.0 5.4 4.6 3.7 3.2 3.3 3.3 3.3
ND ND ND ND
ND ND ND ND
wavelengths every 25 nm. ND = not determined.
integrated rate for a specified layer thickness. The absorbance data are used to calculate the light attenuation with depth in a water column and also the rate of HzO, accumulation throughout the specified wavelength range. The solar flux is specified in the model as a function of time of day, season, total ozone (atmospheric column), and latitude (26). Dissolved humic materials in concentrations commonly encountered in natural systems exhibit a significant absorption of light in the wavelength range beyond 400 nm (Table 111). Therefore, in order to accurately predict the accumulation rate of HzOzthroughout a water column of highly colored water, it is necessary to determine the ap1158
NW Well 1, Miami, FL (TOC = 17.6) Absorb @A
Envlron. Scl. Technol., Vol. 22, No. 10, 1988
surface water VH Pond, Newnans Lake, Miami, FL Gainsville, FL' (TOC = 8.10) (TOC = 11.6) Absorb @A Absorb @A 0.075 0.071 0.068 0.064 0.061 0.058 0.055 0.052 0.050 0.048 0.045 0.039 0.032 0.026 0.020 0.017 0.014 0.011 0.006 5 0.006 5 0.002 5 o.oO0 91 0.000 48 I#J~
are all
7.0 6.6 6.1 5.7 5.2 4.8 4.3 4.1 4.0 3.8 3.7 3.3 2.7 2.2 1.6 1.3 1.3 1.3 0.59 0.59 0.39 0.039 0.015 X
0.240 0.225 0.216 0.207 0.199 0.190 0.182 0.175 0.168 0.161 0.154 0.137 0.115 0.097 0.081 0.068 0.056 0.046 0.028 0.028 0.012 0.0045 0.0014
15 13 12 11
9.7 8.5 7.4 7.0 6.9 6.7 6.5 6.0 5.5 6.0 4.5 4.1 3.7 3.2 0.70 0.70 0.26 0.24 0.06
lo4. Absorb are all cm-'.
parent quantum yields of H202 throughout the range 295-700 nm. Apparent quantum yields were determined for one groundwater and two surface water samples at discrete wavelengths and by using long band-pass filters for wavelengths in the range 400-500 nm. The data are summarized in Table 111,where absorbance (cm-l) and $A are given to 700 nm. Samples of three waters, Newnans Lake, Northwest Well 5, and Coudersport, were chosen for comparison of model calculations to experimentally determined HzOZaccumulation rates. These waters were exposed to sunlight and the accumulation rates determined as outlined above. The
HYDROGEN PEROXIDE
HYDROGEN PEROXIDE ACCUMULATION R A T E ( x
io'
mol L - l
ACCUMULATION R A T E ( x 10'
hr-l
0.1
0
0;2
mol L-'
0.3
hr-l 1
Oi4
0.5
0 0.5
0
1 .o
1.5
2.0
0
0
0
0
0
Midday
50-
I
I
Summer
n
c n Y 0
0
Y 0
I
'
Spring W a t e r ,
Couderaport, P A
Let. 30' Midday
11
I
0
-
I
10 100-1
Flgure 1. Model calculations of the H202accumulation rates showing the effect of long wavelength irradiation at several depths in water from Newnans Lake, Gainesville, FL.
0
Flgure 2. Model calculations of the H202accumulation rates In the relatively transparent spring water from Coudersport, PA. 8
Newnans Lake W a t e r , Surface
r I.
model was run to simulate the same time of day, season, water depth, and latitude, and the results were compared. To approximate the water depth in the quartz flasks, model calculations were specified at 0-, 2-, 4-, 6-, and 8-cm water depth, and the average of these values was used. The Northwest Well 5 sample resulted in a H202accumulation rate of 4.84 X lo4 mol L-' h-' as compared to the model calculations of 5.04 X lo4 mol L-l h-l. The accumulation rate for the Newnans Lake sample was 2.36 X lo4 mol L-' h-l as compared to the model calculation of 2.69 x lo4 mol L-' h-l. In the case of the water obtained from Coudersport, @A could not be determined above 400 nm because of the transparancy of the water above 400 nm (hydrogen peroxide formation was not observed above 400 nm). This observation was supported by the close agreement between the sunlight experiments, which yielded an accumulation rate of 2.67 X lo-' mol L-l h-l, and model calculations (295-400 nm), which gave 2.68 X mol L-l h-l. The agreement between the observed and calculated accumulation rates indicates that the model is accurately predicting H202 accumulation rates at the water body surface. Further, for transparent waters such as Coudersport, it is not necessary to determine'quantum yields above 400 nm. Subsequent to the limited model verification, the photochemical model was used to calculate H202accumulation rates in the waters and to examine the contribution of the longer wavelength radiation to the formation of Hz02. Figure 1shows the calculated accumulation rates at several depths, comparing rates obtained with quantum-yield data for 295-400 nm to those obtained over the range 295-700 nm for the Newnans Lake surface water. Highly colored waters (characterized by high absorbance) rapidly attenuate light in the water column. This results in a greatly reduced rate of HzOzformation (accumulation) with depth. Thus, the calculated H202ac-
5
7
9
11 TIME
Lat.
13
15
zoo
1
summer
17
19
(EST)
Figure 3. Model calculations showing the effect of latitude and season on the surface hydrogen peroxide accumulatlon rate in surface water from Newnans Lake, Gainesville, FL.
cumulation rate at a depth of 10 cm for Newnans Lake water has decreased by 90% from the surface value. On the other hand, the sample from Coudersport does not show a 90% reduction in the H20zaccumulation rate until a depth of 100 cm, Figure 2. It should be noted that the total column density of H202would be the same in the two waters, assuming a depth sufficient to absorb all of the photons and equal apparent quantum yields for both waters. However, in a highly colored water, like Newnans Lake, H202is predominantly formed in the top 10 cm. Therefore, the concentration of H202in the top 10 cm will be much higher than in a relatively transparent water, such as the water from Coudersport, where the formation occurs over a greater depth. Figure 3 summarizes the model calculations for Newnans Lake with @A at wavelengths from 295 to 700 nm. The effect of latitude, at 20' and 40' N, and season on the surface H20zaccumulation rate during the day are shown. It can be seen that daily variations are considerable and in fact, at the lower latitudes, may be more significant than Environ. Sci. Technol., Vol. 22, No. 10, 1988
1159
Environ. Scl. Technol. 1988.22, 1160-1165
seasonal changes on the accumulation of HzOZin a natural water. In the environment, the profiles of Hz02accumulation rate will not necessarily appear as illustrated in Figures 1 and 2. The calculations that resulted in these figures have not taken into account turbulent mixing. Mixing in natural waters is generally considerable when the surface wind is more than a few knots or in the case of flowing streams. Mixing will both dilute H20zdown into the water column and bring water not previously exposed to sunlight to the surface (26). Furthermore, non-light-induced decay rates are likely to vary in different waters depending on such factors as suspended particulate loading, water quality, and biological activity. Other than the recent work on algae (27))these factors have not as yet been studied, and a quantitative knowledge of these decay processes and rates is necessary before diel concentrations of HzOz can be constructed.
Conclusions Hydrogen peroxide is formed photochemically in natural waters containing light-absorbing organic substances. The accumulation rate of H202is related to the concentration of these natural substances and appears to be ubiquitous in its occurrence in natural waters. From the experimentally derived quantum yields, model calculations of Hz02 accumulation rate agree with experimentally determined rates for surface waters. Registry No. HzOz, 7722-84-1. Literature Cited Zafiriou, 0. C.; Joussot-Dubien, J.; Zepp, R. G.; Zika, R. G. Environ. Sci. Technol. 1984, 18, 358A-71A. Moffett, J. W.; Zika, R. G. Mar. Chem. 1983, 13, 239-51. Miles, C. J.; Brezonik, P. L. Environ. Sci. Technol. 1980, 15, 1089-95. Collienne, R. A. Limnol. Oceanogr. 1983,28,83-100. Sinel'nikov, V. E. Gidrobiol. Zh. 1971,7,115-9 (in Russian). Sinel'nikov, V. E.; Demina, V. I. Gidrokim. Mater. 1974, 60, 30-40 (in Russian). Sinel'nikov, V. E.; Liberman, A. S.Tr.-Inst. Biol. Vnutr. Vod Adad. Nauk SSSR 1974, No. 29,27-40 (in Russian). Draper, W. M.; Crosby, D. G. Arch. Environ. Contam. Toxicol. 1983, 12, 121-6. Cooper, W. J.; Zika, R. G. Science (Washington,D.C.) 1983, 220,711-2. Helz, G. R.; Kieber, R. J. Water Chlorination: Chem. Environ.Impact Health Eff. Proc. Conf.1985,5th, 1033-40. Van Baalen, C.; Marler, J. E. Nature (London) 1986,211, 951.
Zika, R. G. Ph.D. Thesis, Dalhousie University, Halifax, NS, 1978, 346 pp. Zika, R. G. In Marine Organic Chemistry;Duursma, E. K., Dawson, R., Eds.; Elsevier: Amsterdam, 1981;pp 299-325. Zika, R. G. EOS, Trans. Am. Geophys. Union 1980, 61, 1010. Zika, R. G.; Saltzman, E. S.; Cooper, W. J. Mar. Chem. 1985, 17, 265-75. Zika, R. G.; Moffett, J. W.; Petasne, R. G.; Cooper, W. J.; Saltzman, E. S. Geochim. Cosmochim. Acta 1985, 49, 1173-85. Baxter, R. M.; Carey, J. H. Nature (London) 1983, 306, 575-6. Draper, W. M.; Crosby, D. C. J. Agric. Food Chem. 1983, 31 , 734-7. Petasne, R. G.; Zika, R. G. Nature (London) 1987, 325, 516-8. Oliver, B. G.; Cosgrove, E. G.; Carey, J. H. Environ. Sci. Technol. 1979, 13; 1075-7. Zepp, R. G.; Wolfe, N. L.; Baughman, G. L.; Hollis, R. C. Nature (London) 1977,267, 421-3. Draper, W. M.; Crosby, D. G. J. Agric. Food Chem. 1981, 29, 699-702. Hoffman, M.; Edwards, J. 0. Inorg. Chem. 1977,16,3333-8. Skurlatov, Y. 1.; Zepp, R. G.; Raugman, G. L. J.Agric. Food Chem. 1983,31,1065-71. Zepp, R. G.; Schlotzhauer, P. F.; Simmons, M. S.; Miller, G. C.; Baughman, G. L.; Wolfe, N. L. Fresenius' 2. Anal. Chem. 1984,319, 119-25. Plane, J. M. C.; Zika, R. G.; Zepp, R. G.; Burns, L. A. In Photochemistry of Environmental Aquatic Systems; Zika, R. G., Cooper, W. J., Eds.; ACS Symposium Series 327; American Chemical Society: Washington, DC, 1987; pp 250-67. Zepp, R. G.; Skurlatov, Y. L.; Pierce, J. T. In Photochemistry of Environmental Aquatic Systems; Zika, R. G., Cooper, W. J., Eds.; ACS Symposium Series 327; American Chemical Society: Washington, DC, 1987; pp 215-24. Holm, T.; George, G. K.; Barcelona, M. J. Anal. Chem. 1987, 59, 582-6. Zepp, R. G.; Cline, D. M. Enuiron. Sci. Technol. 1977,11, 359-66. Kieber, R. J.; Helz, G. R. Anal. Chem. 1986,58, 2311-5. Hatchard, G. C.; Parker, C. A. Proc. R. SOC.London, A 1956, 235, 518-36. Wagner, E. E.; Adamson, A. W. J. Am. Chem. SOC.1966, 88, 394-404.
Received for review July 20,1984. Revised manuscript received October 24,1986. Accepted March 3,1988. Financial support for the research was provided by Office of Naval Research Contract NOOO14-85C-0020 and National Science Foundation Grant OCE 78-25628 and by the Drinking Water Research Center, Florida International University, Miami, FL.
Biodegradation Studies of Aniline and Nitrobenzene in Aniline Plant Waste Water by Gas Chromatography Sampatrao S. Patil and Vijay M. Shlnde"
Analytical Chemistry Laboratory, Institute of Science, Bombay 400 032, India
rn A gas chromatographic (GC) method has been developed for studying the biodegradation of aniline and/or nitrobenzene in aniline plant waste water. The effects of various parameters have been reported and critically discussed. The results are precise and afford simultaneous determinations of aniline and nitrobenzene.
Introduction Aniline and nitrobenzene are used extensively in the 1160
Environ. Sci. Technol., Vol. 22, No. 10, 1988
industries manufacturing synthetic resins, pesticides, dyestuffs, drugs, photographic chemicals, varnishes, vulcanization accelerators, and antioxidants. They are discharged in the aqueous waste which may subsequently accumulate in the environment and prove toxic to living forms. Nitrobenzene is categorized as a priority pollutant by the EPA (1). It causes cyanosis and skin and eye irritation; affects the central nervous system; and produces fatigue, headache, slight dizziness, vertigo, and vomiting (2). Its continuous exposure leads to liver damage,
0013-936X/88/0922-1160$01.50/0
0 1988 American Chemical Society
