Riverborne Contaminants. Similarities between the relative concentrations
of PPE in snow and river water link emissions of airborne
elements to the AR and its tributaries (Fig. S2 C and D).
PPE in the snow pack probably were released as a pulse during
spring melt. In summer, PPE are deposited directly to waterbodies
and the watershed. During snowmelt and rain events, elements are
discharged to surface waters, but a proportion is retained in soil
and vegetation. Particulate and dissolved Ni best represent the
type 1 deposition pattern. In summer, when direct deposition of
airborne contaminants to the river occurs, Ni concentrations are
strongly correlated with concentrations of all other PPE in the AR
and its tributaries (r2 > 0.8, except Ag = 0.5; P < 0.001). In winter,
when airborne elements are deposited to snow on river ice, particulate
deposition of all PPE except Se declines exponentially