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Occurrence and vapor particle partitioning of heavy organic compounds in ambient air in Brazzaville, Congo
Environmental Pollution 76 (1992) 147-156
Occurrence and vapor particle partitioning of heavy organic compounds in ambient air in Brazzaville, Congo Barnabe Ngabe & Terry F. Bidleman Department of Chemistry, University of South Carolina, Columbia, South Carolina 29208, USA (Received 22 January 1991; accepted 28 June 1991) High volume air samples for organochlorine (OC) pesticides, polychlorinated biphenyls (PCB) and polycyclic aromatic hydrocarbons (PAH) were collected during August-September 1989 in Brazzaville, Congo (4.14°S, 15-14°E). Average concentrations (ng/m 3) were ~DDT -- 2-8; Y~HCH (hexachlorocyclohexane) -- 0-42; 3~chlordane -- 0.027; ]~PCB --- 0.55; 5".3-6 ring PAH -- 42; total DDT concentrations in BrazzaviUe fell between those reported in Porto Nova and Delhi (India) and were 20-100 times higher than those found in US cities. The average 3'HCH to a-HCH ratio (11) indicated use of lindane instead of technical HCH. The similarities between chlordane levels in Brazzaville and the open ocean indicated that little or no local use occurs. PAH levels were about equal to or lower than those reported in US cities, whereas PCB levels were three times lower. Vapor/particle distribution coefficients for several OC and PAH were in good correlation with their vapor pressures.The fraction of PAH on particles was greater than that of OC pesticides.
dans l'atmosph6re oc6anique et b, Brazzaville prouvent sa presque ou non utilisation locale. Les concentrations des hydrocarbures aromatiques polycycliques sont inferieures ou 6gales ~ celles rapport6es dans les villes Americaines tandis que celles des polychlorobiph6nyles sont trois fois mains 61ev6es. Les co&ficients de distribution de plusieurs pesticides organochlor6s et des hydrocarbures aromatiques polycycliques entre les phases gaseuses et particulaires sont en bonne corr61ation avec leur pression de vapeur. La fraction particulaire des hydrocarbures polycycliques aromatiques est superieure a celle des pesticides organochlor6s.
RESUME En vue de d6terminer les concentrations atmosph6riques des pesticides organochlor6s, celles des polychlorobiph6nyles et celles des hydrocarbures aromatiques polycycliques, de larges volumes d'air avaient 6t6 collect6s au cours de la p6riode allant d'aofit ~ septembre 1989, Brazzaville (Congo). L ' o n rapporte en ng/m 3 les concentrations moyennes suivantes: 2.8 pour le D D T total, 0.42 pour la somme des hexachlorocyclohexanes, 0-027 pour la somme des chlordanes, 0-55 pour la somme des polychlorobiph6nyles, 42 pour la somme des hydrocarbures aromatiques polycycliques nantis de 3 g 6 noyaux. Les concentrations du D D T total ~. Brazzaville sont comprises entre celles de Porto N o v a et Delhi (Inde) et se retrouvent 20 ~t 100 fois plus 61ev6es que celles trouv6es dans les villes Americaines. La valeur moyenne du rapport a-Hexachlorocyclohexane/yHexachlorocyclohexane qui est de 11 refl~te l'usage du lindane plut6t que celui de l'hexachlorocyclohexane technique. Les concentrations similaires du chlordane
INTRODUCTION Organochlorine (OC) insecticides are used in several tropical and subtropical countries. Although D D T has been banned in North America and Europe, Third World countries still use D D T in the war against malaria and sleeping sickness and in agriculture (Matthielson, 1985; Mitra & Raghu, 1989; Samuel & Pillai, 1989). In India and Central America, re-emergence of malaria has accompanied the rapid spread of mosquito resistance
Environ. Pollut. 0269-7491/92/$05.00 © 1992 Elsevier Science Publishers Ltd, England. Printed in Great Britain 147
148
Barnabe Ngabe, T. F. Bidleman
caused by elevated application of D D T during the late 1960s and 1970s (Chapin & Wasserstrom, 1981). D D T consumption in Africa between 1960-89 has been estimated as 12 930 t (Ottar & Semb, 1991). In Zimbabwe, wildlife has been contaminated with the D D T used in the irradication of the tse-tse fly (Matthielson, 1985). High levels of D D T in plants from the west coast of Africa are indicative of local use (Bacci et al., 1988). Dispersal of pesticides through the atmosphere is responsible for environmental contamination on a regional and global scale (Pacyna & Oehme, 1988; Atlas & Giam, 1989; Patton et al., 1989; Wittlinger & Ballschmiter, 1990). Reports of high levels of D D T and hexachlorocyclohexanes ( H C H ) in the Indian troposphere show that India is a source of these pesticides (Kaushik et al., 1987; Ramesh et al., 1989). The D D T residence time in soils under tropical conditions is relatively short because of volatilization, which is considered to be the most important pathway of dissipation (Sieicher & Hopcraft, 1984; Samuel et al., 1988). Yeadon & Perfect (1981) reported that D D T applied to the soils in Nigeria evaporated with a half-life of only 9 days. Is Africa a major contributor o f D D T and other OC pesticides to the global atmosphere? To our knowledge, no information exists on aerial transport of pesticides in Africa. Other common organic pollutants such as polychlorinated biphenyls (PCB) and polycyclic aromatic hydrocarbons (PAH) have not been measured in air from African cities. This work was carried out to determine the types and levels of airborne OC pesticides, PCB and PAH in Brazzaville, Congo, and to assess the distribution of these compounds between the particle and gas phases.
EXPERIMENTAL Collection of samples Air samples (331q580 m 3) were collected during AugustSeptember 1989 at the top of the American Cultural Center in Brazzaville, Congo. Air was pulled at approximately 0.5 m3/min through two precombusted round glass fiber filters (4 cm diameter Gelman A/E), followed by two 7.8 cm diameter × 7-6 cm thick polyurethane foam (PUF) plugs (density 0.022 g/cm 3) using a Rotron DR-313 brushless pump. P U F plugs were prepared and cleaned as described before (Simon & Bidleman, 1979). The average sampling temperature was 25°C. Other collection data are shown in Table 1. Analytical methods Circles were cut from each filter, weighed, ground in an agate mortar, and total particulate carbon (TPC) was determined by dry combustion (Desert Analytics, Inc.). Total suspended particle concentration (TSP) was
Table 1. Brazzaville sample collection data Sample
Collection dates (1989)
1 2 3 4 5 6 7 8 9 I0 11 12 13 14
8-9 Aug. 9 Aug. 10 Aug. 11-12 Aug. 16 Aug. 17 Aug. 21 Aug. 22 Aug. 23 Aug. 24 Aug. 28 Aug. 29 Aug. 30 Aug. 4 Sept.
Air Total particulate carbon (m3) (p.g/m3) 578 399 428 680 331 331 331 391 391 425 331 331 438 418
12 9-1 9-8 14 9.1 11 11 9.8 10 9.4 9-1 13 7.6 8-1
determined only for sample #14 by weighing the front filter before and after sampling. The ratio TPC/TSP (0.14) was close to that obtained by other researchers in 46 US urban cities. The mean TPC/TSP ratio for these cities was 0.13 + 0.026 (Shah et al., 1986). TSP for other samples was estimated assuming TPC/TSP = 0-14. PUF plugs were individually soxhlet extracted overnight with chromatographic grade petroleum ether. Filters were cut into strips and refluxed for 24 h in dichloromethane. The extract volumes were reduced to approximately 3 ml by means of a rotary evaporator and nitrogen blow-down. Hexane was added to the filter extracts during this step to remove dichloromethane. Extracts were cleaned and separated into two fractions on a column of 3 g 200-mesh silicic acid (5% water added) overlaid by 2 g neutral alumina (6% water added) to separate PCB from most of the OC pesticides and PAH (Bidleman et al., 1987). The fractions were concentrated to 1 ml in the presence of isooctane with a stream of nitrogen. PAH in fraction 2 were determined by capillary gas chromatography-electron impact mass spectrometry (GC-MS) in the selected ion monitoring (SIM) mode, using a Hewlett-Packard 5890 chromatograph and a 5970 Mass Selective Detector under the following conditions: capillary column: 30 m × 0.25 mm i.d. fused silica, DB-1301 bonded phase, 0.25 /zm film thickness (J & W Scientific). Samples were injected splitless (split time = 1 min). The temperature program was: inject at 90°C, hold 1 min, program to 120°C at 20°/min, then to 280°C at 5°/min, hold 16 min. Carrier gas: He 40 cm/s. Detector temperature: 280°C. Ions used for SIM of PAH were: fluorene: 165, 166; PH and AN: 176, 178; AN-dl0: 188; 2-m-PH: 191, 192; FLA and PY: 200, 202; BaA and CHRY: 226, 228; CHRY-dI2: 240; Bbf and BkF: 250, 252; BeP and BaP: 250, 252; BaP-dl2: 264; IcdP and BghiP: 138, 276; BghiP-dl2: 288. Abbreviations for PAH and pesticides are given in Table 2. PAH were quantified relative to the deuterated internal standards.
Heavy organic compounds in air in Brazzaville
149
Table 2. Analytical recovery of PAH and pesticides Compound
Abbreviation
Recovery from spiked PUF plugs ng spiked
Phenanthrene Anthracene 2-Methyl-phenanthrene Fiuoranthene Pyrene Benz(a)anthracene Chrysene Benzo(b)fluoranthene Benzo(e)pyrene Benzo(a)pyrene Indeno(l,2,3-cd)pyrene Benzo(ghi)perylene a-Hexachlorocyclohexane y-Hexachlorocyclohexane trans-Chlordane cis-Chlordane trans-Nonachlor 2,2-Bis(4-chlorophenyl)-l,1dichloroethene 2,2-Bis(4-chlorophenyl)- 1 , 1 dichloroethane 2(2-Chlorophenyi)-2(4-chlorophenyl)- 1,1, l-trichloroethane 2,2-Bis(4-chlorophenyl)- 1,1,1trichloroethane
% Rec+SD (n)
PH AN 2-m-PH FLA PY BaA CHRY BbF BeP BaP IcdP BghiP ot-HCH T-HCH TC CC TN p,p'-DDE
9 260 1 140 4 940 3 320 1 790 1 400 1 000 460 563 472 950 2 000 35.2 34.6 37-5 38-4 37.5 41.6
75+ 16 76+20 83+ 11 87+ 15 90 + 20 106 + 14 110+ 13 104+ 15 103+8.0 99+9.0 107 + 27 106+21 67+ 12 76+ 13 85+ 14 85+ 13 84+8.9 84+ 14
(8) (8) (8) (8) (8) (8) (8) (8) (8) (8) (8) (8) (7) (7) (7) (7) (7) (7)
p,p'-DDD
41.6
99+6.2 (7)
o,p'-DDT
42.6
89+ 13
(7)
p,p'-DDT
42-8
91 + 19
(7)
Recovery from SRM-1649 Found,/xg/g+SD (n) 5.0+0.47 0.41 +0.010 1.1+0.22 5.7+1.6 4-8+1.3 2.6+0.68 4-2+0.85 7.7+2.5 3.0+0.78 2.2+0.29 3.6+0-77 3.6_+0.87
(3) (3) (3) (3) (3) (3) (3) (3) (3) (3) (3) (3)
NIST values a 4.7 0-41 7-1-7.3 6.0-7-2 2.4 3.5-4.6 6-0 3.3-3.9 2.4-3.0 3.3-3.4 4.1-4-7
a Wise et al., 1986. PCB and OC pesticides in fractions 1 and 2 were determined by G C with electron capture detection ( G C ECD) after shaking the solutions with 18 M sulfuric acid. A Varian 3700 chromatograph was used under the following conditions: capillary column: 30 m × 0.25 m m i.d. fused silica, DB-5 bonded phase, 0.25/zm film thickness (J & W Scientific). Samples were injected splitless (split time 0.5 min). The temperature program was: inject at 90°C, hold 1 min, program to 270°C at 6°/min, hold 15 rain. Carrier gas: H2 40 cm/s. Injection port: 240°C. Detector: 320°C. Capel et al. (1985) identified the components of Aroclor fluids from chromatograms on an HP-5 column, which is equivalent to our DB-5. For the most part, we used their G C patterns to identify individual PCB congeners in our air samples and Aroclor 1242 and 1254 standards. Co-injection of five PCB congeners (18, 52, 33, 101 and 153) was performed to check Capel's designations. This proved satisfactory in four cases, however we found that Capel's 146 peak actually matched our 153. Recent multidimensional G C separation of PCB (Schulz et al., 1989) revealed that the 153 peak of Capel et al. is probably 105, and their 66 peak is a mixture of about 90% 95 and only 10% 66. These differences were taken into account in our identifications. Quantitative results were calculated from response factors derived from standard Aroclor 1242 and 1254 injections using the congener percent composition of Capel et al. (1985), with the adjustments for the above discrepancies.
R E S U L T S AND D I S C U S S I O N I Quality control P U F plugs (n = 7-8) were spiked with 563-926 ng individual P A H and 35.2-42.8 ng individual OC. These P U F plugs were analyzed by the same methods used for the field P U F plugs. The mean percent recoveries + SD were: PH: 75 _+ 16%; AN: 76 _+ 20%; 2-m-PH: 83 _+ 11%; FLA: 87 + 15%; PY: 90 _+ 20%; BaA: 106 _+ 14%; C H R Y : 110 + 13%; BbF: 104 _+ 15%; BkF: 106 + 9%; BeP: 103 + 8%; BaP: 99 _+ 9%; IcdP: 107 + 27%; BghiP: 106 + 21%; c~-HCH: 67 _+ 12%; y-HCH: 76 + 13%; TC: 85 + 14%; CC: 85 + 13%; p,p'-DDE: 84 + 14%; p,p'D D D : 99 + 6%; o,p'-DDT: 89 + 13%; p,p'-DDT: 91 + 18%. To check recovery of P A H from particles, 300-mg samples of standard urban air particulate matter from Washington, DC were analyzed. The urban dust was obtained from the National Institute of Standards and Technology (NIST, SRM-1649). The N I S T organic dust was introduced into a pre-extracted cellulose thimble, extracted and analyzed by the same method used for the field filter samples. The mean P A H concentrations in Washington dust from the present work were close to the N I S T values (Table 2). Blank values for P U F plugs and filters are given in Table 3. The quantities of 4-ring and higher PAH and
150
Barnabe Ngabe, T. F. Bidleman
Table 3. Blank values for polyurethane foam plugs and filters ng_+SD PUF (n) PH MePH AN FLA PY BaA CHRY BbF BkF BeP BaP BghiP IcdP a-HCH 3,-HCH TC CC TN p',p-DDE p,p'-DDD o,p'-DDT p,p'-DDT Y.PCB
0-39_+0-05 0.32+0.02 1.32+0.02 2.9+3-5 3.3+4.4 6.7+5.8 1.7_+1.9 2-1_+2-9 1-4_+3.1 1.6+1.6 3.1+3.4 4.2+5.4 0.71-+ 1.92 0.44-+0.35 0.62+0.31 0.050+0-010 0.060+0.019 0.053_+0.021 0-43+0-43 0-39+0.28 0.43_+0.52 0-47_+0.52 13_+8.6
Filters (n) (3) (3) (3) (17) (17) (17) (17) (17) (17) (17) (17) (17) (17) (17) (17) (17) (17) (17) (17) (17) (17) (17) (17)
1.7_+0-098 (3) ND (3) ND (3) 0.39-+0-026(3) 1.1+0.072 (3) 2.4_+0.87 (3) 1-2+0.036 (3) 1.2_+0.026 (3) 0-71_+0.020(3) 0-65-+0-020(3) 1.4+0.030 (3) ND (3) ND (3) 0.040_+0.010 (3) 0.21 -+0.25 (3) 0.14-+0-026 (3) 0-050+0.026 (3) 0.030_+0.010 (3) 0.080_+0.010 (3) 0-060_+0-014 (3) 0-070_+0.017 (3) 0.070_+0-067 (3) 14_+8-9 (3)
OC on back P U F were so low that 14 back P U F and 3 blank P U F were pooled to provide average blanks (n -- 17, Table 3). Sample quantities were considered positive if they exceeded the mean blank by 3 times the standard deviation of the blank. 2 0 r g a n o c h l o r i n e pesticides and PCB levels in air 2.1 D D T DDT-related compounds were found in all samples as shown in Table 4. In Brazzaville's air, p , p ' - D D T (1-2 ng/m3) was the prevalent isomer followed by p,p'Table 4.
D D D (0-63 ng/m3), o , p ' - D D T (0.57 ng/m s) and p,p'D D E (0-37 ng/m3). The concentrations of ]~DDT in Brazzaville are compared with those found from various locations of the world in Table 5. The mean Y D D T in Brazzaville (2.8 ng/m3) ranged between levels in Porto N o v o and Delhi (India) where D D T is still used, and was 20-300 times higher than the levels found in European and North American countries where D D T is not used. With a population of about 500 000 inhabitants, Brazzaville is the capital of Congo. Brazzaville is located on the west side of the Congo River across from Kinshassa (Zaire) where industrial and agricultural activities are more important. In the past and recently, malaria has been a serious problem. For this reason, insecticides have been used against female Anopheles. Unfortunately there is no report available on the types and amounts of insecticides used. 2.2 Hexachlorocyclohexane Africa consumed 11 105 t of H C H products from 1960 to 1989 (Ottar & Semb, 1991). Total H C H (0.42 ng/ms) in Brazzaville was comparable to levels in European and N o r t h American cities and 40-2000 times lower than those in India (Table 5). With a mean of 0.39 ng/m 3, y - H C H was the predominant isomer. H C H products are used in m a n y countries for antimalarial and agricultural purposes. In central Europe where pure lindane (99.5% y - H C H ) is used, 7 - H C H concentrations exceed those of a - H C H (Guicherit & Schulting, 1985; Wittlinger & Ballschmiter, 1987; Chevreuil et al., 1989). In India, technical H C H (70% a - H C H , 14% 7H C H , 9 % / 3 - H C H and 7% 6-HCH) is largely used and in most cases, ot-HCH > y - H C H (Kaushik et al., 1987; Ramesh et al., 1989). In Brazzaville, ratios of ~/-HCH to a - H C H ranged between 6.8 to 20.5 with an average of 10.7. This high y/a ratio can only be due to the use of y - H C H and not technical H C H .
Organochlorines and YPCB in Brazzaville air (ng/m 3)
Sample
p,p'-DDT
o,p'-DDT
p,p'-DDD
p,p'-DDE
y-HCH
a-HCH
transchlordane
cischlordane
1 2 3 4 5 6 7 8 9 10 11 12 13 14
1.2 1-4 1.3 1.4 1.3 0-7 1-2 1.5 1.5 1.3 0.8 1.1 1.2 1.5
0.80 0.30 0-79 0-84 0.35 0.34 0-47 0-38 0.69 0-85 0-30 0.55 0.53 0.75
0-97 0-86 0.65 0-69 0-58 0.31 0.65 0.49 0.31 0.69 0-40 0.50 0.70 0.99
0-78 0-34 0.42 0-56 0-46 0-21 0.24 0.28 0.18 0.46 0.31 0-32 0.35 0.29
0-48 0.38 0.39 0.26 0-41 0-31 0.36 0.40 0.52 0.56 0.30 0.53 0-35 0-27
0.006 8 0.026 0.013 0.027 0-047 0.041 0.043 0-040 0.038 0.045 0.024 0.058 0.036 0.032
0-024 0.006 3 0-009 5 0.006 4 0.019 0-004 3 0.019 0.004 9 0.008 2 0-005 7 0.011 0.008 3 0.008 1 0.005 9
0-019 0-011 0.008 3 0.008 7 0.018 0.003 5 0.006 1 0.005 7 0.006 9 0.005 4 0-011 0-008 5 0.009 2 0-006 7
Mean +SD
1.2 +0.20
0.57 +0.21
0.63 +0.22
0.37 +0-16
0-010 +0.006 1
0.008 5 +0.003 5
0.39 _+0.09
0.034 +0.014
transY~ nonachior PCB 0-013 0.018 0.011 0.008 7 0.015 0-002 2 0-005 0 0-006 4 0.006 6 0.004 0 0-008 1 0-011 0.007 9 0-006 5
0.75 0.91 0-45 0.46 0.65 0.10 0.33 0.58 0.42 0.24 0.49 1-20 0.58 0.48
0.008 8 0.55 _+0.004 +0.28
Heavy organic compounds in air in Brazzaville
151
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152
Barnabe Ngabe, T. F. Bidleman
2.3 Chlordanes The following Southern Hemisphere levels of chlordanes (ng/m 3) have been reported (Kawano et al., 1985; Atlas & Giam, 1989; Wittlinger & Ballschmiter, 1990): Eastern Indian Ocean: 0.019; Western Australia: 0.027; R6union: 0.013-0.027; South Pacific: 0-0010-0-0013. In Brazzaville, the mean concentration of chlordane (cis+ trans-chlordane + trans-nonachlor = 0-027 ng/m3) was comparable to the levels in the atmosphere of the open Southern Hemisphere oceans, and 22-63 times lower than in Columbia, South Carolina, USA and Hyogo, Japan (Table 5). Major chlordane use in the USA and Japan has been for termite control and has led to relatively high levels in ambient air. The fact that chlordane concentrations in Brazzaville are similar to open-ocean concentrations suggests that little or no local use occurs.
with higher vapor pressure predominated. For example, phenanthrene represented 47% of the total PAH. PAH concentrations in Brazzaville were about equal to or lower than those reported in US cities (Table 5). Sources of PAH in Brazzaville may be: (1) auto exhausts; many cars are old and there are no regulations on emissions, (2) refined oil; Brazzaville possesses one of the largest oil depots in the country, (3) wood burning; the majority of the people burn wood for food preparation. 2.6 Vapor-particle relationships
To assess the removal mechanisms, reactivity, and health effects due to inhalation of organic compounds in the atmosphere, a knowledge of the vapor-to-particle partitioning is required. Several studies have shown that the relation between the apparent vapor-to-particle ratio and the liquid vapor pressure of the organic compound (p~.) at a given temperature is:
2.4 P C B
The average distribution of the 42 identified PCB congeners in the air of Brazzaville is shown in Fig. 1. PCB with higher vapor pressures predominated. Total PCB concentrations ranged from 0.1-1.2 ng/m3 (mean -- 0.55) (Table 4). The mean PCB concentration was lower than that observed in US cities and closer to the average reported from Hyogo, Japan (Table 5). Electrical equipment containing transformers and capacitors is widely used in Brazzaville. This may be the source of PCB. Since Brazzaville is a relatively small city, pollutants may also be coming from the neighbouring countries. (e.g. Zaire).
Log A ( T S P ) / F = m log p~. + b
T S P is the particle concentration (/zg/m3), A and F are adsorbent and filter-retained concentrations of organic compounds (ng/m3) (Yamasaki et al., 1982; Bidleman et aL, 1986; Foreman & Bidleman, 1987, 1990; Pankow, 1987; Ligocki & Pankow, 1989). Two PUF plugs were used. The front PUF collected most of the gas-phase compounds and the back PUF was used to monitor the breakthrough losses. The front filter (FF) was assumed to collect particles and filter-adsorbed gases, and the back filter (BF) served to correct for gas adsorption (Ligocki & Pankow, 1989). In this work A and F were calculated from quantities found on the two PUF plugs and filters using relationships given by Ligocki & Pankow (1989):
2.5 P A H
Fluorene was identified but was not quantitatively collected by PUF. The mean concentrations of other PAH are given in Table 6. As shown in Fig. 2, PAH 5
4
3
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]
0
41-
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4-
4-4-
4- -I- ~
4-
4-
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PCB Congener Fig. 1.
(1)
Distribution of PCB congeners in Brazzaville (by IUPAC numbers) as percentage of total.
Heavy organic compounds in air in Brazzaville
153
Table 6. PAH concentrations in Brazzaville air (ng/m3)
Sample
pH
2-MePH
AN
FLA
PY
BaA
CHRY
BbF
BkF
BeP
BaP
1 2 3 4 5 6 7 8 9 10 11 12 13 14
22 24 22 18 18 17 24 26 19 19 32 13 11 17
5-9 5.0 5.2 4.0 5.0 3-0 6.2 6.0 5.0 5-0 7-4 3.0 3.0 5.0
2-2 1-9 1.9 1.8 1.8 1.3 2.1 2.2 1.9 1.9 2.5 1.0 0.8 1.6
4.7 4-9 5.6 5.6 5.5 6.9 6-4 5-9 5.7 4.0 6-4 5.5 4.4 4.8
5.1 5.3 6.0 6.0 6-4 6-9 6.4 6.2 6.9 4.4 6-9 4-5 3.2 5-2
0.48 0-44 0-56 0.78 0.49 0.20 0.68 0-21 0-48 0.42 0.27 0.56 0.38 0.36
1.1 1-0 1-1 1.4 1.1 0-7 1.4 0.8 1.1 1.0 1-1 1-2 0-9 1.0
0-58 0.45 0.98 1.73 0-46 0.42 0.96 0.28 0.43 0.31 0-68 0.63 0.50 0.41
0.94 0-51 0.55 0.87 0.29 0.42 0.65 0.21 0.43 0-30 0.74 0-63 0.45 0-41
0.37 0.15 0.56 0.88 0.25 0.32 0.61 0-17 0.32 0.22 0.66 0.46 0.37 0.31
0-044 0.037 0-39 0-55 0.19 0.19 0-28 0.12 0-16 0.11 0.33 0.22 0.20 0-18
Mean +SD
20 +5-4
4.9 _+1.3
1.8 _+0-5
5.5 _+0.8
5.7 _+0-9
0.45 _+0.17
1.1 -+0.2
0-63 +0-38
0.51 -+0.23
A=PUF+2BF r = F F -- B F
(2) (3)
Average percentages of P A H a n d O C o n b a c k filters, c o m p a r e d to their quantities o n front filters were: P H = 14 + 11; A N = 14 + 16; F L A = 5-9 + 4.8; P Y =5.9 + 4.9; C H R Y = 4.9 + 8.8; B b F -- 1-9 + 1-3; B k F = 1.6 + 1-6; BeP = 1.4 +_ 1.1; p , p ' - D D E -- 13 + 14, p , p ' - D D D = 16 + 13; o , p ' - D D T = 6.4 + 7-0; p , p ' - D D T = 8.2 + 7-3; y - H C H = 37 + 22. Average percentages o f p a r t i c u l a t e O C a n d P A H are shown in Figs 3 a n d 4. Since similar a n d low q u a n t i t i e s of a - H C H were f o u n d o n f r o n t a n d back filters, n o particulate percentage was calculated for a - H C H . Log A ( T S P ) / F for O C a n d P A H was plotted against log p~_ as s h o w n in Fig. 5. Values of p~_ were from Hinckley et al., (1990) (OC) a n d Y a m a s a k i et al., (1984) (PAH). Slopes, intercepts, a n d r2 values were: OC: m = 0.74, b = 5.76, r2 = 0-97; P A H : (PH to BeP): m = 0.81, b = 5-31, r2 = 0.96. I n Fig. 5, the P H a n d A N points seem to deviate in a negative direction. This might be due to the presence o f some ' n o n - e x c h a n g e able' P A H in the aerosols. Ligocki a n d P a n k o w (1989)
B g h i P IcdP 0.58 0-15 1.23 1.54 0.69 0-61 0.90 0-30 0.39 0.38 1.22 0-73 0.83 0.55
0.40 0.21 -+0-21 +0-14
0.72 0.52 +0.39 +0.29
f o u n d a similar situation for fluorene a n d a c e n a p h t h y lene. I f the eqn. (1) regression is performed o m i t t i n g P H a n d A N , the p a r a m e t e r s are: m = 0.93, b = 5.77, r2 = 0.98. Figure 6 shows a c o m p a r i s o n between the fraction o f particle-associated organic c o m p o u n d s as described by J u n g e - P a n k o w (J-P) model (Junge, 1977; Pankow, 1987) a n d Brazzaville data. T h e J - P model is:
4) = cO/(p~ + cO)
(4)
where c = 17.3 pa-cm, 0 -- particle surface area per v o l u m e o f air. F o r u r b a n air 0 = 1-1 × 10 5 cm:/cm3 air (Bidleman, 1988). The curves for Brazzaville O C and P A H were calculated from: = 1/[1 + (A/F)]
(5)
using A ( T S P ) / F from eqn (1) a n d TSP : 73 p,g/m 3. P a r a m e t e r s m a n d b were 0.74 a n d 5.76 for O C a n d 0.81 a n d 5.31 for P A H . The field d a t a for P A H were close to the J - P curve, b u t the D D T c o m p o u n d s a n d T - H C H were less particle associated. The differences between P A H a n d O C suggest different strengths o f adsorption. This was seen in a c o m p a r i s o n of
55
~,~
50
10
45
~2 9 8 < ~.~ 7
40 35
t~ 3 0
6
25
"~
rj ~.. 5 E-~
15 10 5
loll.°.__._ t~
~
m
m
4
3 2 0.18%
~
PAH distribution in Brazzaville, Congo as percentage of total.
i[I
+
m I
m
Fig. 2.
0.73 0.60 0.75 1-35 0.29 0.31 0.61 0.26 0.17 0-42 0.50 0-46 0-50 0.34
Fig. 3.
ra
t::~r'~
"~
o~
ra
Percentage particulate OC.
Barnabe Ngabe, T. F. Bidleman
154 i00 ~.l
80
~ r...)
60
~ ~ ~ * \ \ \
0.8
U~ ~
032099,
40
,< 20
OCs\
o.o
~\\
0,4
0.2
. ' ~\ \
\
m
Fig. 4.
'\J-P
\PAH~
Percentage particulate PAH. 0.0
PAH data from Tokyo and OC from Columbia and Stockholm (Bidleman et al., 1986) and also for PAH and PCB in Chicago (Cotham, 1990), but not seen for PAH and OC in Denver (Foreman & Bidleman, 1990). Another possibility is that the two classes of compounds are on different types of particles. Therefore further investigation into the nature and size of particles should be considered.
10 5
•
g-HCH
10 4
10 a
~ ~,
~rvr o , p ' - D D T
P'P__ -~I~L
~
_
-3
10 5 - 4
i
1
-2
-1
PY ~
I°4
FLA ~ / ~
PH
~ AN
10 3
'~
U9
CHR~BaA Io'
~ i BkF
SLOPE - 08 1
BeP i0 °
_
INTERCEPT i __ -4
k -5
I -3
5.31
i -2
1
10 5
~o'
FLA ~ / ~
10 3
~ AN a
'°2 B b F ~ to'
R
~ i BkF BeP __
I
-5
Log
4
;
0
P L (Pa)
Fig. 6. Junge-Pankow (J-P) model. Particulate fraction (~) of OCs (o) and PAH (V) in Brazzaville compared to those calculated from J P. High volume OC and PAH curves were generated from regression parameters in Fig. 5 (top and middle).
This initial work has shown that OC pesticide PAH and PCB are present in the African troposphere. Of particular interest is the relatively high D D T level (2.8 ng/m3). The reported high rate of D D T volatilization from tropical soils and the relatively elevated levels of D D T in Brazzaville lead to the conclusion that Africa may be another source of D D T to the global atmosphere. Further investigations of atmospheric pesticide levels and deposition processes that could lead to contamination away from sites of application are needed in other African countries. A 1970-71 survey of airborne pesticides in nine states in the USA showed an average ~ D D T concentration of 9.6 ng/m< In Mississippi, a cotton-growing region receiving heavy D D T applications, average ~ D D T levels declined from 100 ng/m 3 in 1972 to 12 ng/m3 in 1974 2 years after D D T usage was stopped. Thus levels of D D T in North American air in the early 1970s were higher than those seen in Africa and India today (Bidleman et al., 1976).
ACKNOWLEDGEMENTS
0.98
SLOPE = 0.93 INTERCEPT = 5 77 I
1
-4
-30
Log
L
. . . . . .
-2
I
_ _
-1
P h(Pa)
Plots of Log A(TSP)/F against p~. OCs; PAHs, regression for all; PAHs, regression for PY-BeP.
Fig. 5.
4
".
/
CHRY ~ B a A
10 °
4
CONCLUSION
INTERCEPT = 5.76 SLOPE = 0.74 R 2 = 0.97
-,o
Support was provided by the US Agency for International Development, the African American Institute, and the National Science Foundation through grant ATM-8612920. The authors are grateful to the authorities of the American Cultural Center in Brazzaville for allowing use of their building for sampling. Contribution 922 of the Belle W. Baruch Institute.
Heavy organic compounds in air in Brazzaville
REFERENCES Atlas, E. L. & Giam, C. S. (1988). Ambient concentration and precipitation scavenging of atmospheric organic pollutants. Water, Air, Soil Pollut., 38, 19-26. Atlas, E. L. & Giam, C. S. (1989). Sea-air exchange of high molecular weight synthetic organic compounds: Results from SEAREX Program. In Chemical Oceanography, Vol. 10, eds. J. P. Riley & R. Chester. Academic Press, London, pp. 33978. Bacci, E., Calamari, D., Gaggi, C., Biney, C., Focardi, S. & Morosini, M. (1988). Organochiorine pesticide and PCB residues in plant foliage (Mangifera indica) from West Africa. Chemosphere, 17, 693-702. Bidleman, T. F. (1988). Atmospheric processes. Wet and dry deposition of organic compounds are controlled by their vapor-particle partitioning. Environ. Sci. TechnoL, 22, 361-7. Bidleman, T. F., Rice, C. P. & Olney, C. E. (1976). High molecular weight chlorinated hydrocarbons in the air and sea: rates and mechanisms of air-sea transfer. In Marine Pollutant Transfer, eds. H. L. Windom & R. A. Duce. Lexington Books, D. C. and Company; Lexington, pp. 323-51. Bidleman, T. F., Billings, W. N. & Foreman, W. T. (1986). Vapor-particle partitioning of semivolatile organic compounds: Estimates from field collections. Environ. Sci. TechnoL, 20, 1038-42. Bidleman, T. F., Wideqvist, U., Jansson, B. (1987). Organochlorine pesticides and polychlorinated biphenyls in the atmosphere of Southern Sweden. Atmos Environ., 21,641-54. Billings, W. N. & Bidleman, T. F. (1983). High volume collection of chlorinated hydrocarbons in urban air using three solid adsorbents. Atmos. Environ., 17, 383-91. Bruckmann, P., Kersten, W., Funcke, W., Balfanz, E., KOnig, J., Theisen, J., Ball, M. & P~ipke, O. (1988). The occurrence of chlorinated and other organic trace compounds in urban air. Chemosphere, 17, 2363-80. Capel, P. D., Rapaport, R. A., Eisenreich, S. J. & Looney, B. B. (1985). PCBQ; Computerized quantification of total PCB and congeners in environmental samples. Chemosphere, 14, 439-50. Chapin, G. & Wasserstrom, R. (1981). Agricultural production and malaria resurgence in Central America and India. Nature, 293, 181 5. Chevreuil, M., Chesterikoff, A., Letolle, R. & Granier, L. (1989). Atmospheric pollution and fallout by PCBs and organochlorine pesticides (Ile-De-France). Water, Air, Soil Pollut., 43, 73 83. Cotham, W. E. (1990). Chemical and physical processes affecting the transport and fate of semivolatile organic contaminants in the environment. PhD dissertation, University of South Carolina, South Carolina, USA. Foreman, W. T. & Bidleman, T. F. (1987). An experimental system for investigating vapor-particle partitioning of trace organic pollutants. Environ. Sci. Technol., 21,869 75. Foreman, W. T. & Bidleman, T. F. (1990). Semivolatile organic compounds in the ambient air of Denver, Colorado. Atmos. Environ., 9, 2405-16. Guicherit, R. & Schulting, F. L. (1985). The occurrence of organic chemicals in the atmosphere of the Netherlands. Sci. Tot. Environ., 43, 193-219. Hermanson, M. H. & Hites, R. A. (1989). Long term measurements of atmospheric polychlorinated biphenyls in the vicinity of superfund dumps. Environ. Sci. Technol., 23, 1253-7. Hinckley, D. A., Bidleman, T. F., Foreman, W. T. & Tuschall, J. (1990). Determination of vapor pressures for nonpolar and semipolar organic compounds from gas chromatographic retention data. J. Chem. Eng. Data, 35, 232 7.
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Junge, C. (1977). Basic considerations about trace constituents in the atmosphere as related to the fate of global pollutants. In Fate of Pollutants in the Air and Water Environments, ed. H. I. Suffet. John Wiley, New York. Part 1, pp. 7-26. Kaushik, C. P., Pillai, M. K. K., Raman, A. & Agarwal, H. C. (1987). Organochlorine insecticide residues in air in Delhi, India. Water, Air, Soil Pollut., 32, 63-76. Kawano, M., Tanabe, S., Inoue, T. & Tatsukawa, R. (1985). Chlordane compounds found in the marine atmosphere from the Southern Hemisphere. Transactions of the Tokyo University of Fisheries, 6, 59-66. Keller, C. D. & Bidleman, T. F. (1984). Collection of airborne polycyclic aromatic hydrocarbons and other organics with a glass fiber filter-polyurethane foam system. Atmos. Environ., lg, 837-45. Ligocki, M. P. & Pankow, J. F. (1989). Measurements of the gas/particle distribution of atmospheric organic compounds. Environ. Sci. TechnoL, 23, 75-283. Ligocki, M. P., Leuenberger, C. & Pankow, J. F. (1985). Trace scavenging of organic compounds in rain-Ill. Particle scavenging of neutral organic compounds. Atmos. Environ., 19, 1619-26. Matthielson, P. (1985). Contamination of wildlife with DDT insecticide residues in relation to tsetse fly control operations in Zimbabwe. Environ. Pollut. Ser. B., 10, 189-211. Mitra, J. & Raghu, K. (1989). Effects of DDT on the growth of crop plants. Environ. Pollut., 61, 157-70. Nakano, T., Tsuji, M. & Okuno, T. (1990). Distribution of PCDDs and PCBs in the atmosphere. Atmos. Environ., 24A, 1361-8. Ottar, B. & Semb, A. (1991). Global significance of the transport and accumulation of polychlorinated hydrocarbons in the Arctic. Proceedings of the 8th International Conference of the Comitk Arctique International ( CAI). Oslo, Norway, 18-22 September, 1989, ed. R. Shearer, Plenum Publishers, New York. Pacyna, M. J. & Oehme, M. (1988). Long range transport of some organic compounds to the Norwegian Arctic. Atmos. Environ., 22, 243 57. Pankow, J. F. (1987). Review and comparative analysis of the theories on partitioning between the gas and aerosol particulate phases in the atmosphere. Atmos. Environ., 11, 2275-83. Patton, G. W., Hinckley, D. A., Walla, M. D., Bidleman, T. F. & Hargrave, B. T. (1989). Airborne organochlorines in the Canadian High Arctic. Tellus, 41B, 243-55. Ramesh, A., Tanabe, S., Tatsukawa, R., Subramanian, A. N., Palanichamy, S., Mohan, D. & Venugopalan, V. K. (1989). Seasonal variations of organochlorine insecticide residues in air from Porto-Novo, South India. Environ. Pollut., 62, 213-22. Samuel, T. & Pillai, M. K. K. (1989). The effect of temperature and solar radiation on volatilization, mineralization and degradation of [14C]-DDT in soil. Environ. Pollut., 57, 63-77. Samuel, T., Agarwal, H. C. & Pillai, M. K. K. (1988). Persistence and binding of DDT and gamma-HCH in a sandy loam soil under field conditions in Delhi, India. Pestic. Sci., 21, 1-15. Schulz, D. E., Petrick, G. & Duinker, J. C. (1989). Complete characterization of PCB congeners in commercial Aroclor and Clophen mixtures by multidimensional gas chromatography-electron capture detection. Environ. Sci. TechnoL, 23, 852. Shah, J. J., Johnson, R. L., Heyerdahl, E. K. & Huntzicker, J. J. (1986). Carbonaceous aerosol at urban and rural sites in the United States. J. Air Pollut. Control Assoc., 36, 254-7.
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Barnabe Ngabe, T. F. Bidleman
Simon, C. G. & Bidleman, T. F. (1979). Sampling polychlorinated biphenyls with polyurethane foam. Chromatographic approach to determining retention efficiencies. Anal Chem., 51, 1110--13. Sleicher, C. A. & Hopcraft, J. (1984). Persistence of pesticides in surface soil and relation to sublimation. Environ. Sci. TechnoL, 18, 514-18. Wise, S. A., Benner, B. A., Chesler, S. N., Hilpert, L. R., Vogt, C. R. & May, W. E. (1986). Characterization of the polycyclic aromatic hydrocarbons from two standard reference material air particulate samples. Anal Chem., 58, 3065-77. Wittlinger, R. & Ballschmiter, K. (1987). Global baseline studies XI: Congener specific determination of polychlorinated biphenyls (PCB) and occurrence of alpha- and gamma-hexachlorocyclohexane (HCH), 4,4'-DDE and 4,4'DDT in continental air. Chemosphere, 16, 2497-513. Wittlinger, R. & Ballschmiter, K. (1990). Studies of the
global baseline pollution XIII. C6-C14 organohalogens aand 3,-HCH, HCB, PCB, 4,4'-DDT, 4,4'-DDE, cis- and trans-chlordane, trans-nonachlor, anisols in the lower troposphere of the Southern Indian Ocean. Fres. J. Anal. Chem., 336, 193-200. Yamasaki, H., Kuwata, K. & Miyamoto, H. (1982). Effects of ambient temperature on aspects of airborne polycyclic aromatic hydrocarbons. Environ. Sci. Technol., 16, 18994. Yamasaki, H., Kuwata, K. & Kuge, Y. (1984). Determination of vapor pressure of polycyclic aromatic hydrocarbons in supercooled liquid phase and their adsorption on airborne particulate matter. Nippon Kagaku Kaishi, 8, 1324-9. (Chem. Abst., 101, 156747 p.). Yeadon, R. & Perfect, T. J. (1981). DDT residues in crop and soil resulting from application to cowpea, Figna unguiculata (L.) Walp. in the sub-humid tropics. Environ. Pollut. B, 2, 275-94.
Occurrence and vapor particle partitioning of heavy organic compounds in ambient air in Brazzaville, Congo Barnabe Ngabe & Terry F. Bidleman Department of Chemistry, University of South Carolina, Columbia, South Carolina 29208, USA (Received 22 January 1991; accepted 28 June 1991) High volume air samples for organochlorine (OC) pesticides, polychlorinated biphenyls (PCB) and polycyclic aromatic hydrocarbons (PAH) were collected during August-September 1989 in Brazzaville, Congo (4.14°S, 15-14°E). Average concentrations (ng/m 3) were ~DDT -- 2-8; Y~HCH (hexachlorocyclohexane) -- 0-42; 3~chlordane -- 0.027; ]~PCB --- 0.55; 5".3-6 ring PAH -- 42; total DDT concentrations in BrazzaviUe fell between those reported in Porto Nova and Delhi (India) and were 20-100 times higher than those found in US cities. The average 3'HCH to a-HCH ratio (11) indicated use of lindane instead of technical HCH. The similarities between chlordane levels in Brazzaville and the open ocean indicated that little or no local use occurs. PAH levels were about equal to or lower than those reported in US cities, whereas PCB levels were three times lower. Vapor/particle distribution coefficients for several OC and PAH were in good correlation with their vapor pressures.The fraction of PAH on particles was greater than that of OC pesticides.
dans l'atmosph6re oc6anique et b, Brazzaville prouvent sa presque ou non utilisation locale. Les concentrations des hydrocarbures aromatiques polycycliques sont inferieures ou 6gales ~ celles rapport6es dans les villes Americaines tandis que celles des polychlorobiph6nyles sont trois fois mains 61ev6es. Les co&ficients de distribution de plusieurs pesticides organochlor6s et des hydrocarbures aromatiques polycycliques entre les phases gaseuses et particulaires sont en bonne corr61ation avec leur pression de vapeur. La fraction particulaire des hydrocarbures polycycliques aromatiques est superieure a celle des pesticides organochlor6s.
RESUME En vue de d6terminer les concentrations atmosph6riques des pesticides organochlor6s, celles des polychlorobiph6nyles et celles des hydrocarbures aromatiques polycycliques, de larges volumes d'air avaient 6t6 collect6s au cours de la p6riode allant d'aofit ~ septembre 1989, Brazzaville (Congo). L ' o n rapporte en ng/m 3 les concentrations moyennes suivantes: 2.8 pour le D D T total, 0.42 pour la somme des hexachlorocyclohexanes, 0-027 pour la somme des chlordanes, 0-55 pour la somme des polychlorobiph6nyles, 42 pour la somme des hydrocarbures aromatiques polycycliques nantis de 3 g 6 noyaux. Les concentrations du D D T total ~. Brazzaville sont comprises entre celles de Porto N o v a et Delhi (Inde) et se retrouvent 20 ~t 100 fois plus 61ev6es que celles trouv6es dans les villes Americaines. La valeur moyenne du rapport a-Hexachlorocyclohexane/yHexachlorocyclohexane qui est de 11 refl~te l'usage du lindane plut6t que celui de l'hexachlorocyclohexane technique. Les concentrations similaires du chlordane
INTRODUCTION Organochlorine (OC) insecticides are used in several tropical and subtropical countries. Although D D T has been banned in North America and Europe, Third World countries still use D D T in the war against malaria and sleeping sickness and in agriculture (Matthielson, 1985; Mitra & Raghu, 1989; Samuel & Pillai, 1989). In India and Central America, re-emergence of malaria has accompanied the rapid spread of mosquito resistance
Environ. Pollut. 0269-7491/92/$05.00 © 1992 Elsevier Science Publishers Ltd, England. Printed in Great Britain 147
148
Barnabe Ngabe, T. F. Bidleman
caused by elevated application of D D T during the late 1960s and 1970s (Chapin & Wasserstrom, 1981). D D T consumption in Africa between 1960-89 has been estimated as 12 930 t (Ottar & Semb, 1991). In Zimbabwe, wildlife has been contaminated with the D D T used in the irradication of the tse-tse fly (Matthielson, 1985). High levels of D D T in plants from the west coast of Africa are indicative of local use (Bacci et al., 1988). Dispersal of pesticides through the atmosphere is responsible for environmental contamination on a regional and global scale (Pacyna & Oehme, 1988; Atlas & Giam, 1989; Patton et al., 1989; Wittlinger & Ballschmiter, 1990). Reports of high levels of D D T and hexachlorocyclohexanes ( H C H ) in the Indian troposphere show that India is a source of these pesticides (Kaushik et al., 1987; Ramesh et al., 1989). The D D T residence time in soils under tropical conditions is relatively short because of volatilization, which is considered to be the most important pathway of dissipation (Sieicher & Hopcraft, 1984; Samuel et al., 1988). Yeadon & Perfect (1981) reported that D D T applied to the soils in Nigeria evaporated with a half-life of only 9 days. Is Africa a major contributor o f D D T and other OC pesticides to the global atmosphere? To our knowledge, no information exists on aerial transport of pesticides in Africa. Other common organic pollutants such as polychlorinated biphenyls (PCB) and polycyclic aromatic hydrocarbons (PAH) have not been measured in air from African cities. This work was carried out to determine the types and levels of airborne OC pesticides, PCB and PAH in Brazzaville, Congo, and to assess the distribution of these compounds between the particle and gas phases.
EXPERIMENTAL Collection of samples Air samples (331q580 m 3) were collected during AugustSeptember 1989 at the top of the American Cultural Center in Brazzaville, Congo. Air was pulled at approximately 0.5 m3/min through two precombusted round glass fiber filters (4 cm diameter Gelman A/E), followed by two 7.8 cm diameter × 7-6 cm thick polyurethane foam (PUF) plugs (density 0.022 g/cm 3) using a Rotron DR-313 brushless pump. P U F plugs were prepared and cleaned as described before (Simon & Bidleman, 1979). The average sampling temperature was 25°C. Other collection data are shown in Table 1. Analytical methods Circles were cut from each filter, weighed, ground in an agate mortar, and total particulate carbon (TPC) was determined by dry combustion (Desert Analytics, Inc.). Total suspended particle concentration (TSP) was
Table 1. Brazzaville sample collection data Sample
Collection dates (1989)
1 2 3 4 5 6 7 8 9 I0 11 12 13 14
8-9 Aug. 9 Aug. 10 Aug. 11-12 Aug. 16 Aug. 17 Aug. 21 Aug. 22 Aug. 23 Aug. 24 Aug. 28 Aug. 29 Aug. 30 Aug. 4 Sept.
Air Total particulate carbon (m3) (p.g/m3) 578 399 428 680 331 331 331 391 391 425 331 331 438 418
12 9-1 9-8 14 9.1 11 11 9.8 10 9.4 9-1 13 7.6 8-1
determined only for sample #14 by weighing the front filter before and after sampling. The ratio TPC/TSP (0.14) was close to that obtained by other researchers in 46 US urban cities. The mean TPC/TSP ratio for these cities was 0.13 + 0.026 (Shah et al., 1986). TSP for other samples was estimated assuming TPC/TSP = 0-14. PUF plugs were individually soxhlet extracted overnight with chromatographic grade petroleum ether. Filters were cut into strips and refluxed for 24 h in dichloromethane. The extract volumes were reduced to approximately 3 ml by means of a rotary evaporator and nitrogen blow-down. Hexane was added to the filter extracts during this step to remove dichloromethane. Extracts were cleaned and separated into two fractions on a column of 3 g 200-mesh silicic acid (5% water added) overlaid by 2 g neutral alumina (6% water added) to separate PCB from most of the OC pesticides and PAH (Bidleman et al., 1987). The fractions were concentrated to 1 ml in the presence of isooctane with a stream of nitrogen. PAH in fraction 2 were determined by capillary gas chromatography-electron impact mass spectrometry (GC-MS) in the selected ion monitoring (SIM) mode, using a Hewlett-Packard 5890 chromatograph and a 5970 Mass Selective Detector under the following conditions: capillary column: 30 m × 0.25 mm i.d. fused silica, DB-1301 bonded phase, 0.25 /zm film thickness (J & W Scientific). Samples were injected splitless (split time = 1 min). The temperature program was: inject at 90°C, hold 1 min, program to 120°C at 20°/min, then to 280°C at 5°/min, hold 16 min. Carrier gas: He 40 cm/s. Detector temperature: 280°C. Ions used for SIM of PAH were: fluorene: 165, 166; PH and AN: 176, 178; AN-dl0: 188; 2-m-PH: 191, 192; FLA and PY: 200, 202; BaA and CHRY: 226, 228; CHRY-dI2: 240; Bbf and BkF: 250, 252; BeP and BaP: 250, 252; BaP-dl2: 264; IcdP and BghiP: 138, 276; BghiP-dl2: 288. Abbreviations for PAH and pesticides are given in Table 2. PAH were quantified relative to the deuterated internal standards.
Heavy organic compounds in air in Brazzaville
149
Table 2. Analytical recovery of PAH and pesticides Compound
Abbreviation
Recovery from spiked PUF plugs ng spiked
Phenanthrene Anthracene 2-Methyl-phenanthrene Fiuoranthene Pyrene Benz(a)anthracene Chrysene Benzo(b)fluoranthene Benzo(e)pyrene Benzo(a)pyrene Indeno(l,2,3-cd)pyrene Benzo(ghi)perylene a-Hexachlorocyclohexane y-Hexachlorocyclohexane trans-Chlordane cis-Chlordane trans-Nonachlor 2,2-Bis(4-chlorophenyl)-l,1dichloroethene 2,2-Bis(4-chlorophenyl)- 1 , 1 dichloroethane 2(2-Chlorophenyi)-2(4-chlorophenyl)- 1,1, l-trichloroethane 2,2-Bis(4-chlorophenyl)- 1,1,1trichloroethane
% Rec+SD (n)
PH AN 2-m-PH FLA PY BaA CHRY BbF BeP BaP IcdP BghiP ot-HCH T-HCH TC CC TN p,p'-DDE
9 260 1 140 4 940 3 320 1 790 1 400 1 000 460 563 472 950 2 000 35.2 34.6 37-5 38-4 37.5 41.6
75+ 16 76+20 83+ 11 87+ 15 90 + 20 106 + 14 110+ 13 104+ 15 103+8.0 99+9.0 107 + 27 106+21 67+ 12 76+ 13 85+ 14 85+ 13 84+8.9 84+ 14
(8) (8) (8) (8) (8) (8) (8) (8) (8) (8) (8) (8) (7) (7) (7) (7) (7) (7)
p,p'-DDD
41.6
99+6.2 (7)
o,p'-DDT
42.6
89+ 13
(7)
p,p'-DDT
42-8
91 + 19
(7)
Recovery from SRM-1649 Found,/xg/g+SD (n) 5.0+0.47 0.41 +0.010 1.1+0.22 5.7+1.6 4-8+1.3 2.6+0.68 4-2+0.85 7.7+2.5 3.0+0.78 2.2+0.29 3.6+0-77 3.6_+0.87
(3) (3) (3) (3) (3) (3) (3) (3) (3) (3) (3) (3)
NIST values a 4.7 0-41 7-1-7.3 6.0-7-2 2.4 3.5-4.6 6-0 3.3-3.9 2.4-3.0 3.3-3.4 4.1-4-7
a Wise et al., 1986. PCB and OC pesticides in fractions 1 and 2 were determined by G C with electron capture detection ( G C ECD) after shaking the solutions with 18 M sulfuric acid. A Varian 3700 chromatograph was used under the following conditions: capillary column: 30 m × 0.25 m m i.d. fused silica, DB-5 bonded phase, 0.25/zm film thickness (J & W Scientific). Samples were injected splitless (split time 0.5 min). The temperature program was: inject at 90°C, hold 1 min, program to 270°C at 6°/min, hold 15 rain. Carrier gas: H2 40 cm/s. Injection port: 240°C. Detector: 320°C. Capel et al. (1985) identified the components of Aroclor fluids from chromatograms on an HP-5 column, which is equivalent to our DB-5. For the most part, we used their G C patterns to identify individual PCB congeners in our air samples and Aroclor 1242 and 1254 standards. Co-injection of five PCB congeners (18, 52, 33, 101 and 153) was performed to check Capel's designations. This proved satisfactory in four cases, however we found that Capel's 146 peak actually matched our 153. Recent multidimensional G C separation of PCB (Schulz et al., 1989) revealed that the 153 peak of Capel et al. is probably 105, and their 66 peak is a mixture of about 90% 95 and only 10% 66. These differences were taken into account in our identifications. Quantitative results were calculated from response factors derived from standard Aroclor 1242 and 1254 injections using the congener percent composition of Capel et al. (1985), with the adjustments for the above discrepancies.
R E S U L T S AND D I S C U S S I O N I Quality control P U F plugs (n = 7-8) were spiked with 563-926 ng individual P A H and 35.2-42.8 ng individual OC. These P U F plugs were analyzed by the same methods used for the field P U F plugs. The mean percent recoveries + SD were: PH: 75 _+ 16%; AN: 76 _+ 20%; 2-m-PH: 83 _+ 11%; FLA: 87 + 15%; PY: 90 _+ 20%; BaA: 106 _+ 14%; C H R Y : 110 + 13%; BbF: 104 _+ 15%; BkF: 106 + 9%; BeP: 103 + 8%; BaP: 99 _+ 9%; IcdP: 107 + 27%; BghiP: 106 + 21%; c~-HCH: 67 _+ 12%; y-HCH: 76 + 13%; TC: 85 + 14%; CC: 85 + 13%; p,p'-DDE: 84 + 14%; p,p'D D D : 99 + 6%; o,p'-DDT: 89 + 13%; p,p'-DDT: 91 + 18%. To check recovery of P A H from particles, 300-mg samples of standard urban air particulate matter from Washington, DC were analyzed. The urban dust was obtained from the National Institute of Standards and Technology (NIST, SRM-1649). The N I S T organic dust was introduced into a pre-extracted cellulose thimble, extracted and analyzed by the same method used for the field filter samples. The mean P A H concentrations in Washington dust from the present work were close to the N I S T values (Table 2). Blank values for P U F plugs and filters are given in Table 3. The quantities of 4-ring and higher PAH and
150
Barnabe Ngabe, T. F. Bidleman
Table 3. Blank values for polyurethane foam plugs and filters ng_+SD PUF (n) PH MePH AN FLA PY BaA CHRY BbF BkF BeP BaP BghiP IcdP a-HCH 3,-HCH TC CC TN p',p-DDE p,p'-DDD o,p'-DDT p,p'-DDT Y.PCB
0-39_+0-05 0.32+0.02 1.32+0.02 2.9+3-5 3.3+4.4 6.7+5.8 1.7_+1.9 2-1_+2-9 1-4_+3.1 1.6+1.6 3.1+3.4 4.2+5.4 0.71-+ 1.92 0.44-+0.35 0.62+0.31 0.050+0-010 0.060+0.019 0.053_+0.021 0-43+0-43 0-39+0.28 0.43_+0.52 0-47_+0.52 13_+8.6
Filters (n) (3) (3) (3) (17) (17) (17) (17) (17) (17) (17) (17) (17) (17) (17) (17) (17) (17) (17) (17) (17) (17) (17) (17)
1.7_+0-098 (3) ND (3) ND (3) 0.39-+0-026(3) 1.1+0.072 (3) 2.4_+0.87 (3) 1-2+0.036 (3) 1.2_+0.026 (3) 0-71_+0.020(3) 0-65-+0-020(3) 1.4+0.030 (3) ND (3) ND (3) 0.040_+0.010 (3) 0.21 -+0.25 (3) 0.14-+0-026 (3) 0-050+0.026 (3) 0.030_+0.010 (3) 0.080_+0.010 (3) 0-060_+0-014 (3) 0-070_+0.017 (3) 0.070_+0-067 (3) 14_+8-9 (3)
OC on back P U F were so low that 14 back P U F and 3 blank P U F were pooled to provide average blanks (n -- 17, Table 3). Sample quantities were considered positive if they exceeded the mean blank by 3 times the standard deviation of the blank. 2 0 r g a n o c h l o r i n e pesticides and PCB levels in air 2.1 D D T DDT-related compounds were found in all samples as shown in Table 4. In Brazzaville's air, p , p ' - D D T (1-2 ng/m3) was the prevalent isomer followed by p,p'Table 4.
D D D (0-63 ng/m3), o , p ' - D D T (0.57 ng/m s) and p,p'D D E (0-37 ng/m3). The concentrations of ]~DDT in Brazzaville are compared with those found from various locations of the world in Table 5. The mean Y D D T in Brazzaville (2.8 ng/m3) ranged between levels in Porto N o v o and Delhi (India) where D D T is still used, and was 20-300 times higher than the levels found in European and North American countries where D D T is not used. With a population of about 500 000 inhabitants, Brazzaville is the capital of Congo. Brazzaville is located on the west side of the Congo River across from Kinshassa (Zaire) where industrial and agricultural activities are more important. In the past and recently, malaria has been a serious problem. For this reason, insecticides have been used against female Anopheles. Unfortunately there is no report available on the types and amounts of insecticides used. 2.2 Hexachlorocyclohexane Africa consumed 11 105 t of H C H products from 1960 to 1989 (Ottar & Semb, 1991). Total H C H (0.42 ng/ms) in Brazzaville was comparable to levels in European and N o r t h American cities and 40-2000 times lower than those in India (Table 5). With a mean of 0.39 ng/m 3, y - H C H was the predominant isomer. H C H products are used in m a n y countries for antimalarial and agricultural purposes. In central Europe where pure lindane (99.5% y - H C H ) is used, 7 - H C H concentrations exceed those of a - H C H (Guicherit & Schulting, 1985; Wittlinger & Ballschmiter, 1987; Chevreuil et al., 1989). In India, technical H C H (70% a - H C H , 14% 7H C H , 9 % / 3 - H C H and 7% 6-HCH) is largely used and in most cases, ot-HCH > y - H C H (Kaushik et al., 1987; Ramesh et al., 1989). In Brazzaville, ratios of ~/-HCH to a - H C H ranged between 6.8 to 20.5 with an average of 10.7. This high y/a ratio can only be due to the use of y - H C H and not technical H C H .
Organochlorines and YPCB in Brazzaville air (ng/m 3)
Sample
p,p'-DDT
o,p'-DDT
p,p'-DDD
p,p'-DDE
y-HCH
a-HCH
transchlordane
cischlordane
1 2 3 4 5 6 7 8 9 10 11 12 13 14
1.2 1-4 1.3 1.4 1.3 0-7 1-2 1.5 1.5 1.3 0.8 1.1 1.2 1.5
0.80 0.30 0-79 0-84 0.35 0.34 0-47 0-38 0.69 0-85 0-30 0.55 0.53 0.75
0-97 0-86 0.65 0-69 0-58 0.31 0.65 0.49 0.31 0.69 0-40 0.50 0.70 0.99
0-78 0-34 0.42 0-56 0-46 0-21 0.24 0.28 0.18 0.46 0.31 0-32 0.35 0.29
0-48 0.38 0.39 0.26 0-41 0-31 0.36 0.40 0.52 0.56 0.30 0.53 0-35 0-27
0.006 8 0.026 0.013 0.027 0-047 0.041 0.043 0-040 0.038 0.045 0.024 0.058 0.036 0.032
0-024 0.006 3 0-009 5 0.006 4 0.019 0-004 3 0.019 0.004 9 0.008 2 0-005 7 0.011 0.008 3 0.008 1 0.005 9
0-019 0-011 0.008 3 0.008 7 0.018 0.003 5 0.006 1 0.005 7 0.006 9 0.005 4 0-011 0-008 5 0.009 2 0-006 7
Mean +SD
1.2 +0.20
0.57 +0.21
0.63 +0.22
0.37 +0-16
0-010 +0.006 1
0.008 5 +0.003 5
0.39 _+0.09
0.034 +0.014
transY~ nonachior PCB 0-013 0.018 0.011 0.008 7 0.015 0-002 2 0-005 0 0-006 4 0.006 6 0.004 0 0-008 1 0-011 0.007 9 0-006 5
0.75 0.91 0-45 0.46 0.65 0.10 0.33 0.58 0.42 0.24 0.49 1-20 0.58 0.48
0.008 8 0.55 _+0.004 +0.28
Heavy organic compounds in air in Brazzaville
151
o
~D
.
.
.
.
.
e~
~5m
+
E
e~
v
>. e~
0 "= q~ I
+
< ,-a
+
Z <
0~ v
eL 0
= e~
6
m
&~
t~q
0
~
o.o.
0
0
O 0
0 o
m
o6
g o
o
0
"= q~
a: o
6c~ ~
~s
6
0
C~
0 0
[..
[..
g-
~oo
ooo
o
0
0o
" 6
g
0 V
0o oo
o
+
0 O~
Ox 0o
0o
>,,
0o
,>
~
0 o ~
+
O~
o~O~B
m
B
z
~ o
> ~
~ ~
"o ~o
~-d~=-~o~ ~-~-~
= -'~
~'-~ =-~-
o
i
+
+
i
oo
.+
¢xl
0
oZ~.>
~• ~
~ "-6
=~
~ ~ d
oo
~ ~
g~
e-~ I~.. £L ~-~.-~
~ d o 8 II
II
II
II
}1
,.II
152
Barnabe Ngabe, T. F. Bidleman
2.3 Chlordanes The following Southern Hemisphere levels of chlordanes (ng/m 3) have been reported (Kawano et al., 1985; Atlas & Giam, 1989; Wittlinger & Ballschmiter, 1990): Eastern Indian Ocean: 0.019; Western Australia: 0.027; R6union: 0.013-0.027; South Pacific: 0-0010-0-0013. In Brazzaville, the mean concentration of chlordane (cis+ trans-chlordane + trans-nonachlor = 0-027 ng/m3) was comparable to the levels in the atmosphere of the open Southern Hemisphere oceans, and 22-63 times lower than in Columbia, South Carolina, USA and Hyogo, Japan (Table 5). Major chlordane use in the USA and Japan has been for termite control and has led to relatively high levels in ambient air. The fact that chlordane concentrations in Brazzaville are similar to open-ocean concentrations suggests that little or no local use occurs.
with higher vapor pressure predominated. For example, phenanthrene represented 47% of the total PAH. PAH concentrations in Brazzaville were about equal to or lower than those reported in US cities (Table 5). Sources of PAH in Brazzaville may be: (1) auto exhausts; many cars are old and there are no regulations on emissions, (2) refined oil; Brazzaville possesses one of the largest oil depots in the country, (3) wood burning; the majority of the people burn wood for food preparation. 2.6 Vapor-particle relationships
To assess the removal mechanisms, reactivity, and health effects due to inhalation of organic compounds in the atmosphere, a knowledge of the vapor-to-particle partitioning is required. Several studies have shown that the relation between the apparent vapor-to-particle ratio and the liquid vapor pressure of the organic compound (p~.) at a given temperature is:
2.4 P C B
The average distribution of the 42 identified PCB congeners in the air of Brazzaville is shown in Fig. 1. PCB with higher vapor pressures predominated. Total PCB concentrations ranged from 0.1-1.2 ng/m3 (mean -- 0.55) (Table 4). The mean PCB concentration was lower than that observed in US cities and closer to the average reported from Hyogo, Japan (Table 5). Electrical equipment containing transformers and capacitors is widely used in Brazzaville. This may be the source of PCB. Since Brazzaville is a relatively small city, pollutants may also be coming from the neighbouring countries. (e.g. Zaire).
Log A ( T S P ) / F = m log p~. + b
T S P is the particle concentration (/zg/m3), A and F are adsorbent and filter-retained concentrations of organic compounds (ng/m3) (Yamasaki et al., 1982; Bidleman et aL, 1986; Foreman & Bidleman, 1987, 1990; Pankow, 1987; Ligocki & Pankow, 1989). Two PUF plugs were used. The front PUF collected most of the gas-phase compounds and the back PUF was used to monitor the breakthrough losses. The front filter (FF) was assumed to collect particles and filter-adsorbed gases, and the back filter (BF) served to correct for gas adsorption (Ligocki & Pankow, 1989). In this work A and F were calculated from quantities found on the two PUF plugs and filters using relationships given by Ligocki & Pankow (1989):
2.5 P A H
Fluorene was identified but was not quantitatively collected by PUF. The mean concentrations of other PAH are given in Table 6. As shown in Fig. 2, PAH 5
4
3
<
]
0
41-
÷
4-
4-4-
4- -I- ~
4-
4-
4-
PCB Congener Fig. 1.
(1)
Distribution of PCB congeners in Brazzaville (by IUPAC numbers) as percentage of total.
Heavy organic compounds in air in Brazzaville
153
Table 6. PAH concentrations in Brazzaville air (ng/m3)
Sample
pH
2-MePH
AN
FLA
PY
BaA
CHRY
BbF
BkF
BeP
BaP
1 2 3 4 5 6 7 8 9 10 11 12 13 14
22 24 22 18 18 17 24 26 19 19 32 13 11 17
5-9 5.0 5.2 4.0 5.0 3-0 6.2 6.0 5.0 5-0 7-4 3.0 3.0 5.0
2-2 1-9 1.9 1.8 1.8 1.3 2.1 2.2 1.9 1.9 2.5 1.0 0.8 1.6
4.7 4-9 5.6 5.6 5.5 6.9 6-4 5-9 5.7 4.0 6-4 5.5 4.4 4.8
5.1 5.3 6.0 6.0 6-4 6-9 6.4 6.2 6.9 4.4 6-9 4-5 3.2 5-2
0.48 0-44 0-56 0.78 0.49 0.20 0.68 0-21 0-48 0.42 0.27 0.56 0.38 0.36
1.1 1-0 1-1 1.4 1.1 0-7 1.4 0.8 1.1 1.0 1-1 1-2 0-9 1.0
0-58 0.45 0.98 1.73 0-46 0.42 0.96 0.28 0.43 0.31 0-68 0.63 0.50 0.41
0.94 0-51 0.55 0.87 0.29 0.42 0.65 0.21 0.43 0-30 0.74 0-63 0.45 0-41
0.37 0.15 0.56 0.88 0.25 0.32 0.61 0-17 0.32 0.22 0.66 0.46 0.37 0.31
0-044 0.037 0-39 0-55 0.19 0.19 0-28 0.12 0-16 0.11 0.33 0.22 0.20 0-18
Mean +SD
20 +5-4
4.9 _+1.3
1.8 _+0-5
5.5 _+0.8
5.7 _+0-9
0.45 _+0.17
1.1 -+0.2
0-63 +0-38
0.51 -+0.23
A=PUF+2BF r = F F -- B F
(2) (3)
Average percentages of P A H a n d O C o n b a c k filters, c o m p a r e d to their quantities o n front filters were: P H = 14 + 11; A N = 14 + 16; F L A = 5-9 + 4.8; P Y =5.9 + 4.9; C H R Y = 4.9 + 8.8; B b F -- 1-9 + 1-3; B k F = 1.6 + 1-6; BeP = 1.4 +_ 1.1; p , p ' - D D E -- 13 + 14, p , p ' - D D D = 16 + 13; o , p ' - D D T = 6.4 + 7-0; p , p ' - D D T = 8.2 + 7-3; y - H C H = 37 + 22. Average percentages o f p a r t i c u l a t e O C a n d P A H are shown in Figs 3 a n d 4. Since similar a n d low q u a n t i t i e s of a - H C H were f o u n d o n f r o n t a n d back filters, n o particulate percentage was calculated for a - H C H . Log A ( T S P ) / F for O C a n d P A H was plotted against log p~_ as s h o w n in Fig. 5. Values of p~_ were from Hinckley et al., (1990) (OC) a n d Y a m a s a k i et al., (1984) (PAH). Slopes, intercepts, a n d r2 values were: OC: m = 0.74, b = 5.76, r2 = 0-97; P A H : (PH to BeP): m = 0.81, b = 5-31, r2 = 0.96. I n Fig. 5, the P H a n d A N points seem to deviate in a negative direction. This might be due to the presence o f some ' n o n - e x c h a n g e able' P A H in the aerosols. Ligocki a n d P a n k o w (1989)
B g h i P IcdP 0.58 0-15 1.23 1.54 0.69 0-61 0.90 0-30 0.39 0.38 1.22 0-73 0.83 0.55
0.40 0.21 -+0-21 +0-14
0.72 0.52 +0.39 +0.29
f o u n d a similar situation for fluorene a n d a c e n a p h t h y lene. I f the eqn. (1) regression is performed o m i t t i n g P H a n d A N , the p a r a m e t e r s are: m = 0.93, b = 5.77, r2 = 0.98. Figure 6 shows a c o m p a r i s o n between the fraction o f particle-associated organic c o m p o u n d s as described by J u n g e - P a n k o w (J-P) model (Junge, 1977; Pankow, 1987) a n d Brazzaville data. T h e J - P model is:
4) = cO/(p~ + cO)
(4)
where c = 17.3 pa-cm, 0 -- particle surface area per v o l u m e o f air. F o r u r b a n air 0 = 1-1 × 10 5 cm:/cm3 air (Bidleman, 1988). The curves for Brazzaville O C and P A H were calculated from: = 1/[1 + (A/F)]
(5)
using A ( T S P ) / F from eqn (1) a n d TSP : 73 p,g/m 3. P a r a m e t e r s m a n d b were 0.74 a n d 5.76 for O C a n d 0.81 a n d 5.31 for P A H . The field d a t a for P A H were close to the J - P curve, b u t the D D T c o m p o u n d s a n d T - H C H were less particle associated. The differences between P A H a n d O C suggest different strengths o f adsorption. This was seen in a c o m p a r i s o n of
55
~,~
50
10
45
~2 9 8 < ~.~ 7
40 35
t~ 3 0
6
25
"~
rj ~.. 5 E-~
15 10 5
loll.°.__._ t~
~
m
m
4
3 2 0.18%
~
PAH distribution in Brazzaville, Congo as percentage of total.
i[I
+
m I
m
Fig. 2.
0.73 0.60 0.75 1-35 0.29 0.31 0.61 0.26 0.17 0-42 0.50 0-46 0-50 0.34
Fig. 3.
ra
t::~r'~
"~
o~
ra
Percentage particulate OC.
Barnabe Ngabe, T. F. Bidleman
154 i00 ~.l
80
~ r...)
60
~ ~ ~ * \ \ \
0.8
U~ ~
032099,
40
,< 20
OCs\
o.o
~\\
0,4
0.2
. ' ~\ \
\
m
Fig. 4.
'\J-P
\PAH~
Percentage particulate PAH. 0.0
PAH data from Tokyo and OC from Columbia and Stockholm (Bidleman et al., 1986) and also for PAH and PCB in Chicago (Cotham, 1990), but not seen for PAH and OC in Denver (Foreman & Bidleman, 1990). Another possibility is that the two classes of compounds are on different types of particles. Therefore further investigation into the nature and size of particles should be considered.
10 5
•
g-HCH
10 4
10 a
~ ~,
~rvr o , p ' - D D T
P'P__ -~I~L
~
_
-3
10 5 - 4
i
1
-2
-1
PY ~
I°4
FLA ~ / ~
PH
~ AN
10 3
'~
U9
CHR~BaA Io'
~ i BkF
SLOPE - 08 1
BeP i0 °
_
INTERCEPT i __ -4
k -5
I -3
5.31
i -2
1
10 5
~o'
FLA ~ / ~
10 3
~ AN a
'°2 B b F ~ to'
R
~ i BkF BeP __
I
-5
Log
4
;
0
P L (Pa)
Fig. 6. Junge-Pankow (J-P) model. Particulate fraction (~) of OCs (o) and PAH (V) in Brazzaville compared to those calculated from J P. High volume OC and PAH curves were generated from regression parameters in Fig. 5 (top and middle).
This initial work has shown that OC pesticide PAH and PCB are present in the African troposphere. Of particular interest is the relatively high D D T level (2.8 ng/m3). The reported high rate of D D T volatilization from tropical soils and the relatively elevated levels of D D T in Brazzaville lead to the conclusion that Africa may be another source of D D T to the global atmosphere. Further investigations of atmospheric pesticide levels and deposition processes that could lead to contamination away from sites of application are needed in other African countries. A 1970-71 survey of airborne pesticides in nine states in the USA showed an average ~ D D T concentration of 9.6 ng/m< In Mississippi, a cotton-growing region receiving heavy D D T applications, average ~ D D T levels declined from 100 ng/m 3 in 1972 to 12 ng/m3 in 1974 2 years after D D T usage was stopped. Thus levels of D D T in North American air in the early 1970s were higher than those seen in Africa and India today (Bidleman et al., 1976).
ACKNOWLEDGEMENTS
0.98
SLOPE = 0.93 INTERCEPT = 5 77 I
1
-4
-30
Log
L
. . . . . .
-2
I
_ _
-1
P h(Pa)
Plots of Log A(TSP)/F against p~. OCs; PAHs, regression for all; PAHs, regression for PY-BeP.
Fig. 5.
4
".
/
CHRY ~ B a A
10 °
4
CONCLUSION
INTERCEPT = 5.76 SLOPE = 0.74 R 2 = 0.97
-,o
Support was provided by the US Agency for International Development, the African American Institute, and the National Science Foundation through grant ATM-8612920. The authors are grateful to the authorities of the American Cultural Center in Brazzaville for allowing use of their building for sampling. Contribution 922 of the Belle W. Baruch Institute.
Heavy organic compounds in air in Brazzaville
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