A Survey of Lentic Waters with Respect to Dissolved and Particulate Lead

Abstract

Some of the strongest temperature inversions in the world occur at Fairbanks, Alaska. Benson (1970) has reported that a temperature gradient of 10 to 30C/1OO m is common in the winter inversions that form at Fairbanks. Air pollution is especially severe during these inversions when it is accompanied by the formation of ice crystals in the air, a condition known as ice fog. This phenomenon occurs when the temperature drops below -20F (-35C) (Benson, 1970), and it intensifies with time if the inversion is not broken. The ice crystals in this fog have been found to adsorb dust and gasses, including the lead halides which are present in the air as a result of the combustion of tetraethyl lead and/or other lead-hydrocarbon compounds used as anti-knock additives in automotive gasoline. Lazrus et al. (1970) have found lead concentrations in precipitation to be highly significantly correlated with the amount of gasoline used in the area sampled. There are two factors that bring the concentration of lead to high levels in ice fogs. Evaporation of the ice crystals tends to concentrate pollutants in the air mass, especially over the core area of the city where precipitation is retarded by the heating effect of the city. Also, during the extreme cold weather accompanying this phenomenon, many people allow their cars to idle when they are parked to increase performance and for reasons of personal comfort. Eventually, much of the pollutants suspended in the ice fog is precipitated and causes unnaturally high levels of lead in the snow. (Winchester et al., 1967). It is suspected that some of this particulate lead collected in the snow may be carried along with the associated surface runoff into 1entic (standing) surface waters during thawing. The objectives of this project were: 1. to measure the amount of dissolved and particulate lead in a number of selected 1entic waters in the Fairbanks area, and 2. to measure the amount of lead that has been incorporated into net plankton organisms located in the selected lentic waters.