Post on 18-Oct-2021
The Alaska Fisheries Science Center Auke Bay Laboratory
The Impacts of Two-stroke Gasoline Engines on Fish
Dr. Jeep Rice
Recreational Boating
• 1 pleasure boat per person in U.S.
• Average use of jetski style craft is 77 hours
• Average for outboard motors is 35 hours
Two-stroke Engines
• Older engines are inefficient
• Can discharge 1/3 uncombusted
• Two-strokes discharge 2-200 million gallons per year
Alaska
Juneau
100 km
Canada
N
S
W E
Auke Lake, Alaska
• Small (46 ha) • 34 m deep • Cold water • Tannin stained • 1103m X 410m • 6 species of salmonids • Used: Apr-Oct by
motor craft
Boat Use on Auke Lake, 2003
0 10 20 30 40 50 60 70 80 90
Apr May Jun Jul Aug Sep Oct
No. of boats
Polycyclic Aromatic Hydrocarbon (PAH) research in Auke Lake Passive samplers (plastic strips)
Integrate over time (21-30 days) Very sensitive
- Seasonal inputs - Recreational use or urban run
off - Spatial trends
- Fingerprint sources
What are PAH and Why Focus on Them?
Paradigm Shift in Ecotoxicity
1970s:1-2 PAH rings
Mono Di PAH
WSF
1990s:3-5 PAH rings
Mono Di PAH
Weatheredoil
LC50 = 1 ppM
effects = 1-20 ppB
Different Toxic Mechanisms –from Different Toxic Compounds
Acute LC50Narcosis
Long Term“Reduced Fitness”
Mono Di PAH
WSF
Mono Di PAH
Weatheredoil
Different Toxic Mechanisms -Benzene
Acute Exposure Chronic Low LevelExposure
“Narcosis” death Leukemia
Why Passive Samplers?
3-4 ring hydrocarbons; pesticides; PCBs
Integrated sampling over time Hot spots; Low concentrations Seasonal Trends
Intermittent inputs
Passive vs Grab Samples
• Integrates over time • Easily deployed • No chemicals • Cover entire time • Sensitive (ppb) • Combines all sources • Standards don’t apply
One time onlySampling gear neededChemicalsCovers 1 time onlyCrude (ppm)Fingerprint sourceMatch State Standards
Bioavailability of Lingering Oil: PEMD Deployment and Retrieval
Polyethylene Membrane Device: PEMD
Seasonal Changes in PAH
0
200
400
600
800
1000
1200
1400
1600
Tot
al P
AH
(ng/
g)
May Jun Jul Aug Sep
PAH at two Depths
0
200
400
600
800
1000
1200
1400
1600
May Jun Jul Aug Sep
Tot
al P
AH
(ng/
g)
1 m 9 m
Interannual Variation in PAH
0
500
1000
1500
2000
2500
3000
3500
4000
Tot
al P
AH
(ng/
g
1999 2000 2001 2002
Boat Use and PAH
May Jul Sep
0
500
1000
1500
Total PAH (ng/g)
0 10 20 30 40 50 60 70 80 90
Apr May Jun Jul Aug Sep Oct
No. of boats
No of boats
PAH Profiles from Auke Lake L P D E
0
5
10
15
20
N0
N1
N2
N3
N4
BP
H
AC
Y
AC
E
F0
F1
F2
F3
D0
D1
D2
D3 P0
P1
P2
P3
P4
AN
T FL
A
PY
R
C1F
B
AA
C
0 C
1 C2
C3
C4
BbF
B
kF
BE
P
BA
P
PE
R
IDP
D
BZ
BzP
Perc
ent o
f tot
al P
AH
G r a b W a te r S a m p l e s
0
1 0
2 0
3 0
4 0
5 0
6 0
7 0
8 0
N0
N1
N2
N3
N4
BP
H
AC
Y
AC
E
F0
F1
F2
F3
D0
D1
D2
D3 P0
P1
P2
P3
P4
AN
T FL
A
PY
R
C1F
B
AA
C
0 C
1 C2
C3
C4
BbF
B
kF
BE
P
BA
P
PE
R
IDP
DB
Z B
zP
Perc
ent o
f tot
al P
AH
Passive Samples – 21 days
Grab Water Samples
(No BTEX)
(No 3-5 ring PAH)
Different Compositions
Different Sources Urban vs Atmospheric inputs Gasoline vs Fuel Oil Combustion vs Spill
Potential Sources of PAH in Auke Lake
• Recreational Use (PWC, motor boats, floatplanes)
• Highway Runoff • Residential Runoff • Wood Smoke
Conclusions
• Personal Watercraft are correlated with seasonal increases in PAH
• PAH are very toxic • Most PAH were in the top meter • Passive samplers successfully monitor
changes in PAH • Goal: Replace 2 stroke with 4 stroke
engines