Two types of mass spectrometry were used for the analysis 

 of high volume air samples. The HCH's, TC, CC, TN, HE, 

 p,p"-DDE and p,p'-DDT were determined by gas 

 chromatography-electron impact mass spectrometry 

 (GC-EIMS) using a Hewlett Packard 5890 GC with a 5970 

 mass selective detector. The instrument contained a 3()-m 

 bonded-phase silica column (6% cyanopropylphenyl, 0.25 |i m 

 film thickness, J & W Scientific). The carrier gas was helium 

 at 30-40 cm s'; the injectorand transfer line temperatures were 

 240°C and 250°C. A 3 m Grob time was used for these 

 analyses. Multiple ion detection ( MID ) employing the following 

 ions was used: HCH 217, 219; HE 353, 355; TC and CC 373, 

 375; TN 407, 409; p,p" -DDT 235, 237; and p,p' -DDE 246, 248, 

 316,318. 



TC, CC, TN, CN, and PCC's were determined by GC- 

 negative ion mass spectrometry (GC-NIMS) with MID using 

 a Finnigan 452 1 C fitted with the same type column as was used 

 for GC-ECD. The carrier gas was helium and samples were 

 injected splitless (3 m Grob time). The ion source was 

 maintained at 80°C and methane at 0. 18 torr was used. Ions 

 monitored were: TC, CC, TN, and CN: 300, 302, 334. 408, 4 10, 

 and 444; PCC's: 309, 311, 343, 345, 379, 381. 413, and 415 

 (Bidleman <>/«/., 1987). 



Air-Sea Equilibration of HCH 



When HCH is at equilibrium between the atmosphere and 

 surface water: 



N = Ko.AC 



(4) 



C,/Cw = H/RT = Kh 



where C,^ and C^ are the concentrations of HCH in air and 

 water, respectively (mol m '), R is the gas constant 

 (8.2 X lO'atmm'mol ' K' ), T is the temperature in Kelvin, H 

 is the Henry's law constant (atm m' mol '), and K,, is the 

 dimension exchange constant between the atmosphere and 

 surface water. Equation 1 is an expression of Henry's law. H 

 was determined in the laboratory for a-HCH and y-HCH over 

 the range of environmental temperatures in seawater using a 

 gas stripping method (Mackay ei al., 1979) and a dynamic 

 headspace method (Yin & Hassett, 1986). Details of these 

 experiments are found in Hinckley (1989). The temperature 

 dependence of H for a-HCH in seawater is 



log H (atm m' mol ') = (-31381 174)/T -i- (5.61 ±0.66) (2) 



and for -HCH the relation is; 



log H (atm m' mol ') = (-3183 ± 99)/T + (5.29 ± 0.34). (3) 



A two-layer model has been proposed for the study of gas 

 exchange between air and sea (Liss & Slater. 1974). In this 

 model an air film lies above and a water film below the 

 interface. Transport of HCH through the interface occurs by 

 molecular diffusion across the concentration gradients in both 

 the air and water films. Usually resistance in one film dominates 

 the exchange across the interface. Fick's first law applies to the 

 fiux of HCH across the air-water interface: 



where N is the fiux of HCH through the interface, AC the 

 difference in HCH concentration between the air at the 

 interface and the well mixed troposphere, and K<,,\ is the overall 

 exchange constant that includes resistances in the air and water 

 films. Since the ratio of resistances to gas exchange for HCH 

 between the air and water phase, R^w>100 (Hinckley, 1989), 

 KoA is essentially the same as k,^ (exchange constant for the air 

 phase, m s '). Assuming that the concentration of HCH in 

 interfacial air is in equilibrium withC^, introduction of Equation 

 1 leads to 



N = k, (K„Cw - CJ. 



(5) 



According to Equation 5, a negative flux is from air to sea and 

 a positive flux is from sea to air. 



Mackay and Yeun ( 1983) developed an equation relating 

 kA(ms ') in the environment to the wind speed (m s ') at 10 m 

 (U|n) and the gas phase Schmidt number (Sc): 



k^(ms') = 46.2 x 10'^(6.1 -h0.63U,„)"'U|oSc' 



(6) 



Using a procedure similar to that of Mackay and Yeun 

 (1983), Sc was calculated for HCH, which was found to be 

 independent of temperature, equal for both isomers of HCH, 

 and equal to 2.9. Calculations for k^ were done by using 

 Equation 6 for the locations listed in Table 5 and ranged from 

 (1) 1.2 X 10' m s' at Station 110 (53°56'N, 175°58'E) to 

 1.0 X loams' at Station 100(64°23'N. 169°09'W). Detailsof 

 these calculations can be found in Hinckley (1989). 



Results and Discussion 



Quality Control 



Spike recoveries of 10-17 ng HCH in water, 17 ng HCH 

 from PUF (low volume air system), and 7-8 ng of chlordanes, 

 and HCH and DDT's from PUF (high volume air system), 

 shown in Tables 2a and 2b, ranged from 64 to 119%. 

 Concentrations reported in this paper have been corrected for 

 recovery. Breakthrough from front to back PUF (100 x back 

 PUF/front PUF) averaged 1 8% for -HCH and 1 2% for HCB in 

 the low volume air collection. Breakthrough for a-HCH and 

 y-HCH ranged from 10-50% and 2-12% respectively in high 

 volume air collection. Breakthrough of the chlordanes ranged 

 from 1-5%, p,p'-DDT and p,p'-DDE 1-2%, o,p'-DDT 6%, 

 and p,p'-DDD 13%. Concentrations reported are the sum of 

 front and back PUF. Limits of detection (LOD) (Tables 2a,b), 

 based on analysis of blank cartridges (Hinckley & Bidleman. 

 1989). analysis of liquid-liquid procedural and control blanks, 

 and PUF plugs, were 0. 1 ng/1 for a-HCH and y-HCH in water. 

 20 pg/m' in air for a-HCH by ECD (low volume system), and 

 0.2-0.3 pg/m' for chlordanes by MS and HCH's and DDT's by 

 ECD in the high volume system. Since the levels of y-HCH in 

 air were only about three times the LOD with the low volume 

 system. y-HCH was only quantified in the high volume air 

 samples. 



269 



