1988;H;irgravee/a/., 1988). Taken together, the HCH isomers 

 are the most abundant of the heavy organochlorines in northern 

 troposphere and surface waters. As a result, low volumes of air 

 (10-20 m^) are sufficient for the analysis of 

 a-HCH, and a-HCH and y-HCH can be determined in 2-4 1 

 water. A knowledge of air and surface water HCH 

 concentrations, along with the appropriate Henry ' s law constants 

 and wind speed, allows the flux of HCH's across the air-sea 

 interface to be calculated. For these reasons, the HCH's are 

 appealing compounds for studying the air-sea exchange of a 

 high molecular weight gas. Previous studies of air-seaexchange 

 of halogenated organic gases have examined freons and low 

 molecular weight chlorinated hydrocarbons such as CCI4 and 

 CHCI3 (Hunter-Smith et al., 1983; Khalil et al., 1983; Singh 

 e/ a/.. 1983). 



Experimental Methods 



Cruise Track 



Cruise AK-47 originated and terminated at the deep-water 

 port of Dutch Harbor, Alaska, and lasted from 26 July- 

 2 September 1988. Surface (2 m) water concentrations of 

 a-HCH and y-HCH determined at 19 stations of the AK-47 

 cruise, and air concentrations of a-HCH and hexachlorobenzene 

 (HCB) were measured at 16 stations. Hexachlorocyclohexane 

 and other OC concentrations in the microlayer (top 120 ^ m) 

 and surface water (2 m) were compared at one station. Four 

 high volume air samples were taken for y-HCH, heptachlor 

 epoxide (HE), trans-chlordane (TO, cis-chlordane(CC),trans- 

 nonachlor (TN), cis-nonachlor (CN), p,p'-DDT, o,p"-DDT, 

 p,p'-DDD, p,p'-DDE, polychlorinated biphenyls (PCB), and 

 polychlorinated camphenes (PCC). 



Sample Collection 



Surface water was collected using a sampler based on a 

 design by Keizer ef a/. ( 1 977 ). This was constructed using two 

 empty 4-1 glass bottles in protective plastic casings (Solvent 

 bottle carriers, Nalgene Corp.) mounted on a wooden frame. 

 Teflon elbows were cemented into the bottle caps, with a glass 

 tube connecting the two bottles through the elbows. A messenger 

 sent down the wire broke the glass tube, allowing water to fill 

 the bottles within 5 min. Microlayer water samples were 

 collected at one station from a small boat at least 1 km from the 

 ship using a stainless steel screen (Garrett, 1965; Rice et al. 

 1982). At each station the surface water temperature and 

 salinity were noted from a conductivity/temperature/depth 

 (CTD) probe, and wind speed was taken from the ship's 

 meteorological station. 



Low-volume air samples were taken using a pressure- 

 vacuum pump (Millipore Corp. ). Air w as pumped through two 

 or three polyurethane foam (PUF) plugs (4.8-cm diameter, 

 3.2-cm thickness) in a thick-walled glass tube (4.0-cm ID, 

 15-cm length) for 8-24 h at a flow rate of 20 1/mm, yielding 

 volumes of 9.2-28.3 m'. Flow rates were monitored using an 

 in-line Top-Trak Model 820 mass flowmeter (Sierra 

 Instruments). Because of the low air volumes only a-HCH and 

 HCB were quantified with this system. 



High volume air samples were taken using a Rotron 

 DR-313 brushless pump. The air was pulled through a 

 20 X 25-cmGelmanAEbinderless glass-fiber filter (OFF) and 

 two 7. 8-cm diameter x 7.5-cm thick PUF plugs at a flow rate 

 of 0.4-0.5 mVmin for 3 days to yield 1.790-2,160 m' air. 

 Details of this system are provided by Billings and Bidleman 

 (1980. 1983). In both high and low volume systems 

 breakthrough of analytes from front to back PUF plugs was 

 monitored by the separate analysis of each plug. Samples and 

 field spikes were immediately analyzed on board ship or were 

 stored in a freezer (-20°C). 



Field high and low volume air sample spikes were prepared 

 by pipetting 1.0 ml of a calibration standard containing 

 8-17 ng/ml organochlorine pesticides (OC) onto clean PUF 

 plugs. Blank PUF's and GFF's were brought to the ship and 

 returned with the samples. Water spikes were prepared by 

 pipetting 1.0 ml of a calibration standard containing 

 10-17 ng/ml a-HCH and y-HCH in acetone to 3.5 1 water and 

 extracting the spike using the method described below. 

 Concurrent analysis of ambient water concentrations was done 

 and the spike experiments were corrected for ambient HCH 

 levels. 



Preconcentration and Cleanup 



Analytes from 3.5 I water were preconcentrated by two 

 methods: liquid-liquid extraction into 300 ml dichloromethane 

 (DCM) and adsorption onto Cg bonded-phase cartridges 

 ( Hinckley & Bidleman, 1989). The C, bonded-phase cartridges 

 were eluted with 3 ml 1:1 ethyl ether-hexane. Polyurethane 

 foam plugs were extracted for 6-8 h in a Soxhlet apparatus with 

 petroleum ether. Glass-fiber filters were cut into strips, placed 

 in round-bottom flasks and refluxed in DCM for 8 h. All 

 sample extracts were reduced and transferred to hexane or 

 isooctane by rotary evaporation and nitrogen blowdown. High 

 volume air samples were split into two fractions using a column 

 of silicic acid and neutral alumina (Keller & Bidleman, 1984; 

 Bidleman et al., 1987). All extracts were treated with 

 concentrated sulfuric acid for cleanup before gas 

 chromatographic (GC) analysis. 



Gas Chromatographic Analysis 



Gas chromatographic analysis of air and water samples 

 .was done using a number of detection systems. 

 Hexachlorocyclohexanes in water, HCH"s and HCB in low 

 volume air samples, and DDT and its breakdown products; and 

 PCB in high volume air samples were determined by GC with 

 electron capture detection (GC-ECD), carried out using a 

 Hewlett Packard 5840, Varian 3700, or Carlo Erba 4160 

 chromatographs with '''Ni ECD's. The instruments 

 contained 25-m bonded-phase fused silica columns 

 (polydi-methylsiloxane, S'/r phenyl, 0.25 |i m film thickness, 

 Hewlett Packard or SGE Corp.). Carrier gases were hydrogen 

 or helium at 30-40 cm s ', the injector temperature was 240°C 

 and the detector was 320°C. Samples were injected using a 

 Grob technique (30 s split time). Chromatographic data were 

 collected using the HP-5840 integrator, a HP-3390A. or 

 Shimadzu Chromatopac CR3A integrator. 



268 



