The role of algal carbon in
the formation of THMs
J.D. Jack, T. W. Sellers, P. A. Bukaveckas, D.
McGaha and J. Shostell
Department of Biology and Center for
Watershed Research, University of Louisville
Louisville, KY (USA)
Trihalomethanes (THMs)
Chlorination of water supplies is
commonly used as a disinfection practice
worldwide
While effective, this process can also
produce potentially harmful disinfection by
products such as trihalomethanes (THMs).
THMs include chloroform etc.
Trihalomethanes
Previous observational and experimental
work with THM formation potential
(THMFP) in source waters:
THMFP is directly proportional to TOC,
temperature and pH
THMFP may be influenced by CHLa and
algal extracellular products
Evidence for both autochthonous and
allocthonous sources of THM precursors
Research Approach
Comparative: Survey of THMFP and other
parameters in the Ohio River mainstem
and 5 major tributaries during different
hydroperiods
Experimental: Mesocosm studies at three
hydroperiods in which we assessed
THMFP under different light regimes
RM 534
Kentucky
River
Wabash
River
Louisville
RM 782
Green
River
RM 938
Tennessee
River
Cumberland
River
500
THMFP
ug/L
400
300
A O
200
100
0
O hio- 1
O hio- 1
Oh1
Oh1
space
KY
Ky
KY
KY
space
O hio- 3
Oh2
O hio- 3
Oh2
space
G r een
Gr
G r een
Gr
space
Wabash
Wa
Wabash
Wa
space
Cum b
Cu
Cum b
Cu
space
TN
Tn
TN
space
O hio- 5
Oh3
Tn
THMFP in August (A) and October (O)
2000 in the Ohio River and major
tributaries
O hio- 5
Oh3
space
80
CHLa
ug/L
60
40
A O
20
0
O hio- 1
O hio- 1
Oh1
Oh1
space
KY
Ky
Ky
KY
space
O hio- 3
Oh2
O hio- 3
Oh2
space
G r een
Gr
G r een
Gr
space
Wabash
Wa
Wabash
Wa
space
Cum b
Cu
Cum b
Cu
space
TN
Tn
TN
Tn
space
O hio- 5
Oh3
O hio- 5
space
Oh3
Chlorophyll concentrations in August (A) and
October (O) 2000 in the Ohio River and
major tributaries
Experimental Study
Experiments performed at the Ohio River
Experimental Station in 2000 L
mesocosms
Experiments were conducted in July,
August and September to capture range
of river conditions
River water pumped into mesocosm and
mixing maintained by submersible pumps
Experimental Study
Tank covers were used to create different light
environments and thus indirectly control algal
bloom development
Dark-tank covered, no light (N=3)
Ambient-simulates light in deep portions of the river
(N=3)
High light-simulates light in shallow portions of river
(N=3)
Tanks sampled for THMFP, CHLa, DOC, POC,
TN and TP on days 0,3,6,10
Chlorophyll 
ORES Experiment 3
16
High Light
14
HA
Chlorophyll  (g/L)
12
HA/HN
10
8
6
Amb. Light
LA
LA/LN
4
2
LA/River/DA
Dark
DA
0
0
3
6
Treatment Day
9
12
D THM
September 2000
Dark
Ambient Light
140
High Light
-1
THM ( g L )
120
100
80
60
40
20
0
Day 3
Day 6Day 6
Day Day
1010
DTHM
ORES Experiment 3
140
Dark
THMFP (g L-1)
120
100
High Light
80
Low Light
Dark
60
40
20
0
0
3
6
Treatment Day
9
12
Results
Comparative data: consistent with hypothesis
that algal production promotes THMFP (both
CHLa and THMFP were highest in Wabash).
Experimental data: consistent with above
hypothesis. High light tanks exhibited larger
increases in CHLa and greater changes in
THMFP than those observed in low light tanks.
Minimum of 96% of THM in the dissolved form
(< 0.45 m)
Relevance to Ecosystem
Questions
Factors controlling DOC flux from drainage
Role of allocthonous and autochthonous
sources of DOC in rivers
Input-output budgets to determine carbon
transformations and THMFP production
Acknowledgements
Thanks to Rich Schultz for analysis work
We gratefully acknowledge USEPA, the
Technical Assistance Center for Water
Quality at Western Kentucky University
and CSX Corporation for funding of this
research and the Ohio River Experimental
Station.