wAbstract
@The Scioto
River is a major tributary to the Ohio
River, which runs from its headwaters in row crop dominated
agricultural lands in central Ohio, south through the city of
Columbus, the 15th largest city in USA. During a high flow event
in April 2004, water was collected from seven locations along
the river, and analyzed for a number of chemical constituents
including total and dissolved Hg. Total Hg concentration increased
continually downstream with the highest concentrations found at
Commercial Point, just below two large sewage treatment plants
that serve metropolitan Columbus. The highest Cl- concentration
was also found there. The highest NO3-
concentrations were found in the agriculturally dominated portion
of the river. The highest dissolved Hg concentration occurred
in downtown Columbus. Using flow data from the day when the samples
were collected, Hg yields were calculated at three locations within
the basin: at Prospect in the northern, agriculture-dominated
part of the basin; at Bellepoint located upstream of two reservoirs,
just north of Columbus proper; and at downtown Columbus. The dissolved
Hg yields in ng km-2 s-1 increased by a
factor of 2 from Prospect to Bellepoint and then another 50 at
Columbus. The particulate Hg yields increased only 10 from Prospect
to Bellepoint, but 30 from Bellepoint to Columbus, with the particulate
Hg yields about `2.5 to 4.5 times greater than the dissolved ones.
These data suggest that yields of particulate Hg are affected
more by urbanization than agricultural activities. The cause of
the increasing yields of dissolved Hg as the river proceeded downstreams
is not clear at this time. It is assumed that the last increase
is due to input from the urbanized portion of the watershed. As
demonstrated previously, it appears that urbanized regions may
retain a lower percentage of atmospherically deposited Hg than
other landscape types.x
1. Introduction
2. Environmental setting
3. Methods
4. Results
5. Discussion
@5.1. Estimated atmospheric input to central Ohio
@5.2. Land use and total Hg concentrations in rivers/streams
@5.3. Dissolved Hg and its relationship to DOC
@5.4. Particulate Hg and reservoir removal of Hg
6. Conclusions
Acknowledgements
References