Due Diligence Investigations of Novel Copper-alloy Mesh ...

Environmental aspects of copper alloy mesh1

Robert Dwyer, (International Copper Association), Patrick Earley, Brandon Swope (US Navy SPAWAR), Juan Carlos Torres (CODELCO), Scott Smith, Holly Gray, (Wilfrid Laurier University), Uwe Hofmann (Wieland Werke)

February 2015

Due Diligence Investigations of Novel Copper-alloy Mesh Materials in Aquaculture: - Measured copper release rates - Modeled and measured ambient concentrations - Measured uptake in cultured fish - Predicted bioavailability to other aquatic organisms

Why copper alloys?

2

• Durable in the offshore environment

• Solid track record in marine engineering

• Low corrosion rates

• Strong and rigid

• Easy to fabricate

• 100 percent recyclable

Environmental aspects of copper alloy mesh

Advantages of copper-alloy net pens

3

• Stays naturally clean while maintaining maximum water exchange

• Reduced impact from pathogens and parasites, as monitored by farmers

• Reduces drag and maintains cage volume

• Reduces escapes from predation and storm damage

• Presents extended pen life and recyclability

• Provides low total cost of ownership


How much copper is lost due to corrosion?How do CAM releases of copper compare to releases from current antifoulant-treated netting?

Laboratory and field measurements of copper releases due to normal corrosion4 Environmental aspects of copper alloy mesh

Major objective of copper-alloy mesh products: Reduce metal loss to extend working life with minimal maintenance

Corrosion sequence for copper alloys in seawater:

• Bare (“bright”) metal initially oxidizes with relatively soluble corrosion products (oxides, hydroxides)

• Over several weeks, relatively soluble corrosion products are replaced by less and less soluble salts: copper chlorides, copper carbonates

• These low-solubility corrosion salts form a protective patina on surfaces to inhibit further corrosion and metal loss

5 Environmental aspects of copper alloy mesh

Copper releases to seawater during this corrosion sequence

• Laboratory experiments: “Jar” tests (Major Testing Lab, Germany)

• Field measurements: “Dome” tests (U.S. Navy, San Diego)


Laboratory corrosion tests (Germany)


Field tests of copper release and toxicity (CA-U.S. Navy)


Copper release rates—current practice: Nylon mesh coated with antifoulant


0 50 100 150 200 250 300 350 4000

20

40

60

80

100

120

140

160

180

200

Elapsed time, days

Cop

per

rele

ase,

μg/

cm2-d

ay

Nylon net-FlexGuard)

Source: Brooks, K.M., 2000

0 50 100 150 200 250 300 350 4000

20

40

60

80

100

120

140

160

180

200

Copper release rates—current practice: Nylon mesh coated with antifoulant

10

0 50 100 150 200 250 300 350 4000

20

40

60

80

100

120

140

160

180

200

Elapsed time, days

Cop

per

rele

ase,

μg/

cm2-d

ay

Nylon net-FlexGuard

FlexGuard (extrapolated)

Source: Brooks, K.M., 2000


0 50 100 150 200 250 300 350 4000

20

40

60

80

100

120

140

160

180

200

Copper release/corrosion rates—current practice vs. new copper alloy (brass) mesh

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0 50 100 150 200 250 300 350 4000

20

40

60

80

100

120

140

160

180

200

0 50 100 150 200 250 300 350 4000

20

40

60

80

100

120

140

160

180

200

Elapsed time, days

Cop

per

rele

ase,

μg/

cm2-d

ay

Nylon net-FlexGuard


Germany-Lab

Source: Hofmann et al., in prep.Environmental aspects of copper alloy mesh

12

0 50 100 150 200 250 300 350 4000

20

40

60

80

100

120

140

160

180

200

0 50 100 150 200 250 300 350 4000

20

40

60

80

100

120

140

160

180

200

0 50 100 150 200 250 300 350 4000

20

40

60

80

100

120

140

160

180

200

0 50 100 150 200 250 300 350 4000

20

40

60

80

100

120

140

160

180

200

Elapsed time, days

Cop

per

rele

ase,

μg/

cm2-d

ay

Nylon net-FlexGuard


Germany-Lab

Navy Dome-Field

Source: Earley et al., in prep.

Copper release/corrosion rates—current practice vs. new copper alloy (brass) mesh


Comparative copper release rates from CAM and AF-coated nylon, over a typical grow-out cycle


Elapsed time

Cop

per

rele

ase

Nylon coating replacement cycle

Copper-alloy meshreplacement cycle

Release rate—conclusions

• Copper-alloy mesh release rates decrease rapidly as bright metal forms protective patina

• Total metal loss: < 2 percent over five- to eight-year lifetime in the water (based on initial pilot tests; agrees with extrapolation of these test data)

• CAM release rates over a grow-out cycle: much less than AF-treated nylon (where releases will “spike” every four – eight months when freshly-treated nylon net replaces copper-depleted and fouled net)



Zinc Releases from CAM Brass

Zinc Release Rates from 65:35 Brass Mesh


0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 3800

10

20

30

40

50

60

70

80

90

100

Zn

Day

Rele

ase

Rate

mg

cm-2

d-1

How much do copper concentrations increase in nearby waters?Do copper concentrations near CAM pens comply with water quality standards?

Measured Nearfield Copper Concentrations at a Site in British Columbia, Canada17 Environmental aspects of copper alloy mesh

3 km

Sampling locations—British Columbia, Canada

18

Photo Credit: Google Maps


Background Cu levels


Upstream of

PensDownstream of

PensDawley

Passage

[Cu] Total

- Day 1 (Nov. 26)

- Day 2 (Nov. 27)

[Cu] Dissolved

- Day 1 (Nov. 26)

- Day 2 (Nov. 27)

Source: Smith et al., in prep.

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Co

nce

ntra

tion

( µg

Cu/

L)

Downstream samples over time

20

0,0

0,5

1,0

1,5

2,0

2,5

3,0

Co

nce

ntr

atio

n (

µg

Cu

/L)

6 8 9 15 20

Day


Source: Smith et al., in prep

Downstream samples over time

21

6 8 9 15 20

Day

0,0

0,5

1,0

1,5

2,0

2,5

3,0

Co

nce

ntr

atio

n (

µg

Cu

/L)

[Cu] Total

[Cu] Dissolved

Environmental aspects of copper alloy mesh Source: Smith et al., in prep

Conclusions

• Measured values are below applicable British Columbia water quality standards for copper.

• No consistent patterns to indicate detectable amounts of copper are being released from the newly-installed cages.


23

Is the released copper “bioavailable” to aquatic life in nearby waters?

Application of the Marine Copper Biotic Ligand Model to the British Columbia Data


Downstream dissolved Cu concentrations

24

6 8 9 15 20Day

[Cu]Diss

SMAV[Cu]Diss

Species Mean Acute Value (SMAV)• Average of EC50 data• Mytilus edulis

- Most sensitive organism in marine database


Source: Smith et al., in prep

0

2

4

6

8

10

12

Co

nce

ntra

tion

(µg

Cu/

L)

How much do copper concentrations increase in nearby sediments?

Planned sediment monitoring, per ASC Salmon Standard


Copper Monitoring Requirements(per Salmon Standard 1.0 of Aquaculture Stewardship Council)

From Appendix I-1. Sampling methodology for calculation of faunal index, macrofaunal taxa, sulphide and redox, and copper:

3. Three [stations] should be 25 meters outside the Allowable Zone of Effect (AZE), or 55 meters from the edge of the array of cages measured with a marked line and recorded using GPS. Of these, one should be upstream and one downstream with respect to the direction of the residual current, and the other should be to one side of the farm in a direction orthogonal to the residual current

4. [Duplicate samples] from [three ]reference sites 500-1000 meters from the farm (edge of the array of cages), in similar water depth and substratum type (where this exists), and recorded using GPS.

Timing shall also be the same, sampling at peak cage biomass during the production cycle.


Sediment Sampling – Current Status

CAM Salmon Pilot Test Sites:

• All salmon sites previously used copper-based antifouling coatings on polymer nets

• These sites have elevated and variable copper background, due to past or current deployment nearby of AF-coated pens

• Thus, these sites unsuitable for identifying discrete accumulation from CAM pens

Sea Bass site in Vietnam:

• No copper antifoulants used in the past

• Full-life cycle 3 m x 3m x 3m pens deployed in April, 2014

• Sediment sampling planned


Additional analyses to determine Bioavailable copper in sediments

Sediments to be analyzed for:

• Total copper

• Simultaneously Extracted Metals (SEM)

• Acid-Volatile Sulfide (AVS)

• Organic Carbon

• Concentrations in <63 um fraction (Simpson, S. et al. CSIRO 2009)


How can you estimate how many CAM pens can safely be installed at a site?

Predicting the “Carrying Capacity” of a Fjord in British Columbia using MAMPEC29 Environmental aspects of copper alloy mesh

Extrapolation of conservative release rate estimates to real pen deployments: MAMPEC


MAMPEC predictions for closed BC fjord

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0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0 10 20 50 100 150 200

Tota

l Cu

(ug/

L)

N°of Cages

Cu Release Rate = 20 ug/cm2/d

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0 10 20 50 100 150 200

Tota

l Cu

(ug/

L)

N° of Cages


0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0 10 20 50 100 150 200

Dis

solv

ed C

u (u

g/L)

N° of Cages


0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0 10 20 50 100 150 200

Dis

solv

ed C

u (u

g/L)

N° of Cages


0.00

2.00

4.00

6.00

8.00

10.00

0 10 20 50 100 150 200Cu in

Sed

imen

ts 2

yea

rs (u

g/gd

w)

N° of Cages


0.00

2.00

4.00

6.00

8.00

10.00

0 10 20 50 100 150 200Cu in

Sed

imen

ts 2

yea

rs (u

g/gd

w)

N° of Cages


0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0 10 20 50 100 150 200

Tota

l Cu

(ug/

L)

N°of Cages


0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0 10 20 50 100 150 200

Dis

solv

ed C

u (u

g/L)

N° of Cages


0.00

2.00

4.00

6.00

8.00

10.00

0 10 20 50 100 150 200Cu in

Sed

imen

ts 2

yea

rs (u

g/gd

w)

N° of Cages



Conclusion: Releases of copper to the aquatic environment from CAM corrosion

• Even with 200 pens deployed in small bay, predicted increase in total copper likely < 0.5 mg/L.

• Bioavailable fraction (basis for regulatory standards in U.S. and EU) much lower still.

• Therefore, no likelihood of exceedance of marine environmental quality standards for copper.

32Source: Torres et al., in prep.


Does the copper accumulate in the tissue of the fillets headed to market?How do copper levels in CAM-farmed fish compare to conventional pen-farmed salmon, or wild-caught salmon?

Tissue measurements in CAM-farmed Salmon


Copper concentrations in salmon fillets

CAM Atl. Salmon (Chile)Wild BC Salmon

Farmed BC Atl. Salmon

0,00

0,20

0,40

0,60

0,80

1,00

1,20

1,40

1,60

minimum

mean

maximum

Copper Concentration,mg/kg, wet wt.

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Sources: EcoSea, in prep. (Chilean salmon)Kelly, B.C. et al., 2008 (BC wild and farmed salmon)


Conclusion: No food safety issues

Copper concentrations in fillets of Atlantic Salmon harvested from copper-alloy mesh pens are no different from copper concentrations in :

• Wild-caught Pacific salmon

• Atlantic salmon raised in conventional nylon pens (with copper AntiFouling coatings)

35 Environmental aspects of copper alloy mesh35

Summary

Economics, growth performance and disease

• Lower incidents of disease

• Lower operating costs

• Less environmental impact

Environmental effects and food safety

• Reduced copper releases relevant to current coated nylon technology

• Copper levels in fish tissue—equivalent to wild caught salmon


Thank You!


For more information please contact:

[email protected]

Or visit:

CuAquaculture.org

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Due Diligence Investigations of Novel Copper-alloy Mesh ...

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