The Pb content in orchard soils at Mission Peninsula, Michigan was det
ermined to assess the impact of historical lead arsenate applications.
Soil samples at 72 sites located in five orchards were collected at d
epths of 2-, 20-, 50-, and 100 cm. Atomic absorption spectroscopy was
used to quantify Pb levels (mu g g(-1)). Mean surface Pb levels at ind
ividual orchards ranged from <1-136 mu g g(-1) and rapidly decreased w
ith depth, to <1-5 mu g g(-1) at 100 cm. The impact of textural class
and slope angle on Pb levels was also analyzed. Correlation coefficien
ts linking Pb levels with textural class were weak, ranging from 0.21
to -0.07. Varying slope steepness and slope position within orchards f
ailed to affect the spatial pattern of soil Pb. Soil Pb levels were al
so compared at 5 sites along local roads with varying levels of automo
bile traffic. Samples were collected 1 m from the roadside at the same
depth intervals studied in orchards. Average daily traffic along the
busiest roadsites ranged from 8200 to 16 000; these sites had Pb level
s of 90-210 mu g g(-1). Such locales had Pb levels similar to the more
intensively sprayed orchards.