Spatial and Temporal Trends of Atmospheric Organochlorine Vapors in the Central and Upper Great Lakes

Abstract

monthly air samples were collected from Saginaw Bay, Sault Ste. Marie (SSM), and Traverse City, MI, to identify spatial and temporal variation in organochlorine (OC) vapors in the central and upper Great Lakes region. Average annual and maximum concentrations of ∑PCB were highest at Traverse and lowest at SSM. PCB 8+5 dominated the congener mix, except at Traverse in the summer. Maxima of HCB, R-and γ-HCH, DDT, and DDE were observed at Traverse or Saginaw, except one unusual event at SSM in May. All compound concentrations varied seasonally at all sites except R-HCH. Correlations measuring regression strength between air temperature and OC concentrations show Saginaw affected most by local sources, and SSM affected the least. Among compounds with high vapor pressure, correlations were low at Traverse indicating nonlocal sources. The spatial and temporal differences observed may limit prediction of regional atmospheric trends of these compounds.

Temporal and Spatial Trends in a Long-Term Study of Gas-Phase PCB Concentrations near the Great Lakes

“…Overall, yearly average values (( standard error) ranged from a low of 89 ( 11 pg/m 3 at Eagle Harbor in 1991 to a high of 370 ( 51 pg/m 3 at Sturgeon Point in 1993. These concentrations are well within the range of values reported for gas-phase PCB concentrations near the Great Lakes (2,6,32,34,37,41,42). Some spatial variation was seen in the results.…”

Spatial and temporal trends of gas and particle phase atmospheric DDT and metabolites in Michigan: Evidence of long‐term persistence and atmospheric emission in a high‐DDT‐use fruit orchard

“…The peak concentration at South Haven of all 6 compounds combined (ΣDDT) on a given date (8,122 pg m −3 ) is about 20 times greater than observations at any other Great Lakes or upper Midwest site reported since 1990 [ Buehler et al , 2001; Hawthorne et al , 1996; Hoff et al , 1992, 1996; McConnell et al , 1998; Monosmith and Hermanson , 1996] which show a maximum ΣDDT (sum of p , p ′‐DDT and p , p ′‐DDE) concentration of about 417 pg m −3 over Lake St. Clair [ McConnell et al , 1998]. This peak concentration of ΣDDT is also about 8 times greater than average concentration in Belmopan, Belize in the mid‐1990s (992 pg m −3 ), where a regional current DDT use was suspected [ Alegria et al , 2000], perhaps in Mexico at the time [ Lopez‐Carrillo et al , 1996], and in Zimbabwe in 1994 (1050 pg m −3 ) where it was used as late as 1988 [ Larsson et al , 1995].…”

“…Four surrogate standards were added before extraction began (PCB 14, PCB 65, PCB 166, δ ‐HCH). Extracts were volume‐reduced by rotary evaporation and were separated into 2 fractions using elutions of hexane and 40/60 (v/v) DCM/hexane through silica‐gel deactivated 3.5% with purified H 2 O [ Hermanson et al , 1997; Monosmith and Hermanson , 1996]. Both fractions were analyzed for all 6 DDT‐group compounds by gas chromatography with electron capture detection (GC‐ECD) using a 60‐m DB‐5 column, and quantified using PCB 204 as an internal standard.…”

Causes of Variability in Pesticide and PCB Concentrations in Air near the Great Lakes

“…Previous studies that have detected possible agricultural inputs of lindane near the Great Lakes have been based in Canada or on time scales of a year or less (25)(26)(27)(28)(29); thus, the discovery of more than 10 years of agricultural application effects at U.S. sampling sites is significant and somewhat unexpected. These effects are apparent in the parameter estimates (a4 to a6) for the agricultural application cycle of γ-HCH (see Table 1).…”