Bromide Levels in Mon Rose in 2010, Remain High
Pittsburgh Post-Gazette
4 November 2011
By Don Hopey,
Bromide levels rose in the Monongahela River in 2010 and remain
elevated, possibly because of discharges of wastewater from
Marcellus Shale drilling or electric power plants, said Jeanne
VanBriesen, a Carnegie Mellon University civil and environmental
engineering professor who spoke Thursday at a university research
symposium about the river.
Ms. VanBriesen, who is also director of CMU's Center for Water
Quality in Urban Environmental Systems, said the river's bromide
levels are much higher than what would be expected in similar
inland waterways and should be reduced to ensure that public
drinking water supplies remain safe.
Bromides are nontoxic salt compounds, but they react with
disinfectants used by municipal water treatment plants to form
brominated trihalomethanes, also known at THMs, which are volatile
organic liquid compounds that become part of the drinking water.
The more bromides in the river water, the more THMs in the
finished water, and studies show a link between ingestion of THMs
and several types of cancer and birth defects.
"THMs are carcinogenic for long-term exposures," Ms. VanBriesen
said, "so you don't want to keep putting more bromide into the
[Mon] river basin."
Eleven public water treatment intakes are on the Monongahela
River, supplying approximately 350,000 customers. Ms. VanBriesen's
two-year study sampled river water at eight locations near public
drinking water intakes and focused on chloride and bromide,
elements that are components of total dissolved solids.
"Bromide going into the river system started to increase in
mid-2010, and, if you look deeper, the relative amount of bromide
is increasing," Ms. VanBriesen said. "It's an indication that
something is changing in the basin. Freshwater shouldn't have this
much bromide."
This spring, the Ohio River Valley Water Sanitation Commission
designated bromide as a "compound of concern" for water treatment
plants.
Ms. VanBriesen said her research hasn't pinpointed a single source
but said bromide is contained in water discharges from air
pollution control devices at coal-fired power plants and in
wastewater or "produced water" from Marcellus Shale drilling
operations.
Controls on some discharges from likely bromide sources and a much
wetter 2011 that diluted bromide concentrations, she said,
produced more stable water quality in the river this year compared
with 2010, which was drier, reducing river flow.
Don Hopey: dhopey@post-gazette.com or 412-263-1983.