Atmospheric deposition of anthropogenic air pollutants contributes to degra
dation of water quality in the Great Lakes and other water bodies and is in
dicative of atmospheric pollution. In this paper, we discuss deposition of
three air pollutants: atrazine; total phosphorus; and nitrogen (total Kjeld
ahl nitrogen and nitrate) to Lake Michigan. Throughout 18 months in 1994-19
95, over 600 atmospheric samples (gas, particulate, and precipitation combi
ned) were collected and analyzed for persistent organic pollutants and nutr
ients. Here the measurements and modeled deposition estimates are presented
for atrazine, phosphorus, and nitrogen. Results indicate that concentratio
ns of atrazine in precipitation have remained constant over 5 years (0.10-0
.40 mu g L-1), consistent with the nearly constant sales rate of the herbic
ide over that time period. Actual loading of atrazine to the lake was less
in 1994-1995 (1.04 x 10(3) kg y(-1)) than in 1990-1991 (2.6 x 10(3) kg yr(-
1)). This difference in loading is due to lower overall precipitation in 19
94-1995. Phosphorus concentrations in precipitation, on the other hand, hav
e decreased from an average of 57 mu g as P L-1 in 1976 to an average of 6.
36 mu g as P L-1 for 1994-1995. Nitrate deposition has decreased by a small
, but not statistically significant, amount since the late 1970s.