Atmospheric Transport of Toxaphene from the Southern United States to the Great Lakes Region

Abstract

Toxaphene was used extensively as an insecticide on cotton in the southern United States until its use was restricted in 1982. Toxaphene has been found in the water and fishes from the Great Lakes, and several authors have qualitatively linked this observation to atmospheric transport from the southern United States, although no detailed field study has been done to confirm this suggestion. We implemented a sampling network to measure the gas-phase concentrations of toxaphene near Lake Michigan at Sleeping Bear Dunes, MI; Bloomington, IN; Lubbock, TX; and Rohwer, AR. The toxaphene concentrations referenced to 288 K were 11 +/- 1, 25 +/- 1, 160 +/- 3, and 950 +/- 30 pg/ m3, respectively. We combined these concentration data with a nonparametric, backward trajectory, multiple regression model of the following form: ln(P) = a0 + a1/T + a2theta where P is the partial pressure of toxaphene (in atm) in a given sample, T is the atmospheric temperature at the sampling site during sampling (in degrees Kelvin), and theta is 0 if the backward trajectory comes from the north and 1 if the trajectory comes from the south. The parameters of this model were generally significant, giving a temperature coefficient (a1) corresponding to 45 +/- 8 kJ/mol and a positive directional coefficient (a2) of 0.6 +/- 0.2 (except for Texas, which was not significant). The positive sign and magnitude of the directional coefficient indicates that the sources of toxaphene are located south of the sampling sites. We also compared the chemical behavior of toxaphene in the atmosphere and found that the congener ratios were similar at the different sampling sites but slightly different from various toxaphene standards.

Radial Dilution Model for the Distribution of Toxaphene in the United States and Canada on the Basis of Measured Concentrations in Tree Bark

“…These low levels are expected given that toxaphene was never even licensed for use in Canada (25,33). It is known that toxaphene is being transported in the atmosphere from the southern United States to the Great Lakes, so it is likely that toxaphene found in Canada is also a result of similar processes (4,19,34).…”

“…Because toxaphene was never used in the Arctic, atmospheric transport (likely from the southern United States) is the sole contributor of toxaphene to this region. Most recently, James and Hites conducted a comprehensive study to measure the atmospheric transport of toxaphene from cotton-growing locations in Texas and Arkansas to Indiana and northern Michigan (19). Toxaphene has been measured at other locations in the United States and Canada as well (20)(21)(22)(23)(24)(25).…”

Toxaphene trends in the Great Lakes fish

“…A change in the input rate by the mid-1990s would be expected since toxaphene was banned in 1982 and the input of toxaphene to the Great Lakes is mainly atmospheric deposition (James et al, 2001;James and Hites, 2002;Ma et al, 2005aMa et al, , 2005b. To examine the more recent trends, exponential decay regression for all of the lakes was performed using the data from 1994 to 2009.…”

Model predictions of toxaphene degradation in the atmosphere over North America

“…Furthermore, pesticides can be transported in the atmosphere over long distances from their application sites to contaminate ecosystems such as the Arctic and the Great Lakes [1,2].…”

“…Moreover, scarce information and few experimental data are available on chemical reactions of pesticides in the environment, and the knowledge of pesticide transformation is very limited [11]. Consequently, most current transport models [2,12,13] simulate environmental pesticides without considering other pollutants such as atmospheric aerosols and ozone; therefore, they do not have detailed representation of interactions among all the important species, which may significantly affect the fate and transport of pesticides. Additionally, these models are unable to address chemical degradation of pesticides.…”