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

摘要

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