How harmful is Copper?

Mike Waldock

Centre for Environment Fisheries and Aquaculture Science, UK

Risk Assessment

Predicted No Effect Concentration (PNEC)

Predicted Environment Concentration (PEC)> 1 (risk of harm)

Risk assessment is relatively simple - if there is likely to be more toxic substance in the water than is known to affect animals, then alarm bells ring

Copper the problem

• For some harbours and marinas monitoring data based measuring total copper dissolved in the water shows higher concentrations than lab studies show effects on mussels. So there must be harm.

• What is wrong with the assessment?

Copper the Problem

* “but this [harm] cannot be firmly concluded because an unknown proportion of each [copper and zinc] was probably complexed with dissolved organic matter, and therefore less bioavailable”

Nearly all testing of copper has been done in clean seawater without natural complexing agents

*P. Matthiessen, J. Reed and M. Johnson , 1999. Sources and potential effects of copper and zinc concentrations in the estuarine waters of Essex and Suffolk, UK. Marine Pollution Bulletin 38(10):908-920

Copper testing the uncertainty

If the form (species) of copper present in the environment dictates toxicity•We need to measure these forms•Need to test the toxic effects of these forms on animals•Need to compare toxic values with concentrations of copper in the real world

Copper species toxicity

LC 50 (b)

Dissolved copper concentration

All alive

All dead

LC 50 (a)

Measuring Copper – analytical methods

• Range of techniques used previously, many have complicated steps

• Our target - simple robust speciation of dissolved copper into labile (toxic ions and salts) and non-labile (less toxic complexed organic forms)

DPASV

Testing in experimental systems

Copper species Total

dissolved

labile

How do you keep this constant if the ratio changes

with time?

LC 50 (b)

Dissolved copper concentration

All alive

All dead

LC 50 (a)

Flow-through copper dosing

system

• Filtered seawater input in to system to reduce background DOC.

• CuCl2 stock solution

• Dissolved organic carbon source as humic acid (HA).

• Cu aged (>32h) prior to exposure to test animals

Mussel Larvae

0 10 20 30 40 50 60 70

0

20

40

60

80

100Total Cu EC50 = 12.37

Labile Cu EC50 = 5.4

120 140 160

Copper concentration (μg l-1)

% n

orm

al D

-larv

ae

Copper concentration µg/l

% n

orm

al D

larv

ae

Total Cu EC50 = 12.37 parts per billion

Labile Cu EC50 = 5.4

Cu speciation with Humic Acid

0 5 10 15 20

0

20

40

60

80

100

n = 5

Nominal HA concentration (mg l-1)

% o

rgan

ic c

oppe

r

Oyster Embryo Bioassay

Copper Toxicity to Oyster Embryos

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5

0

10

20

30

40

50

TDCu

LCu

corrected DOC concentration (mg l-1 C)

Cop

per

EC50

val

ue

Concentration of labile (toxic) copper at which half the

oysters die stays the same with increasing

humic acid

DOC (HA) concentration mg/l

Cop

per E

C50

µg/l

High levels of dissolved copper are needed to kill the oysters in the presence of humic

acid

Copper toxicity to Oysters

• The EC 50 for dissoved copper to oyster embryos doubles from 20 to 40 parts per billion (µg/l) in the presence of humic acid

• The EC50 for labile copper is around 7µg/l and unchanged as humic acid increases

Copper Toxicity to FucusFucus germling growth test

Obtain gametes

Fertilise eggs to create zygotes

Attach to microscope

slides

Zygotes measuredon days

0, 4, 7, 10, 14. Place slides within experimental tanks of the flow-through System. Copper

concentration range0, 20, 40, 80, 160

320 µg l-1 Cu

Test terminatedon day 14

day 0

day 4

day 7

day 10

day 14

Increase HAdosing

Copper toxicity to Fucus

0.5 1.0 1.5 2.0 2.5 3.0 3.5

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

TDCu

LCu

measured DOC concentration (mg l-1)

Cop

per

EC50

( μg

l-1)

Measured DOC concentration

Cop

per E

C50

µg/

lRequires more dissolved

copper to affect fucus growth as DOC increases

Copper Toxicity to Fucus

• It takes 70 µg/l of dissolved copper to halve the growth rate of fucus if there is 2.5 mg/l of DOC in the water

• The EC50 for labile (toxic) copper is around 20µg/l.

How much toxic copper is out there?

• Previous Monitoring biased to discharges• Our strategy examined:

– Different types of sites – harbour/open marina/estuary

– Different levels of humics in the water– Different levels of suspended sediment– Different seasons– Different depths– Different countries

How much toxic copper is out there?

HarwichMilford Haven

Plymouth

Southampton

Total Dissolved Copper µg/l at Ocean Village Marina, 1m depth

00.5

11.5

22.5

33.5

Feb May Aug Sept

estuaryouter marina

inner marinainner marina

Estuary Total Dissolved and Labile Copper

0

0.5

1

1.5

2

2.5

3

ug/l

Total D CuLabile CuMean TDCu1.27Mean L Cu 0.24

Plymouth Southampton Milford Haven

Copper in the real world

• Around 20% in toxic forms, higher proportions of toxic forms close to inputs and lower levels as samples age (further from point sources)

• Only one sample of 324 measurements exceeded the EQS (harmful level)

Finland

. Aerial view of Uittamo marina located in Turku, Finland. Numbers denote sampling sites.

43

21

40 m400 m

Labile Copper in FinlandLa

bile

cop

per c

once

ntra

tion

(µg/

l)

Surface1

Bottom1

Surface2

Bottom2 Surface

3 Bottom3 Surface

4 Bottom4

SpringSummer

AutumnWinter0.0

0.5

1.0

1.5

2.0

2.5

Labile and Total Dissolved Copper in Finland

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

Sur

face

1m a

bove

Sur

face

1m a

bove

Sur

face

1m a

bove

Sur

face

1m a

bove

Sur

face

1m a

bove

Sur

face

1m a

bove

Sur

face

1m a

bove

Sur

face

1m a

bove

Sur

face

1m a

bove

Sur

face

1m a

bove

Sur

face

1m a

bove

Sur

face

1m a

bove

Sur

face

1m a

bove

Sur

face

1m a

bove

Sur

face

1m a

bove

Sur

face

1m a

bove

1 1 2 2 3 3 4 4 1 1 2 2 3 3 4 4 1 1 2 2 3 3 4 4 1 1 2 2 3 3 4 4

Dis

solv

ed c

oppe

r con

cent

ratio

n (u

g l-1

)

LCu

TDCu

Spring Summer Autumn Winter

TDCu concentration is the total column height

Risk QuotientsTotal Dissolved Copper: worst case

Predicted No Effect Concentration = 5

Measured Total Dissolved Copper = 6.68 (3.60)1.34=

Predicted No Effect Concentration = 5

Measured labile copper = 2.69 (0.38)0.54=

In marina Outside marina

0.72

In marina Outside marina

0.08

Total DCu Labile

No. Samples 108 108Mean (µg/l) 1.68 0.3895%ile (µg/l) 4.18 0.71Max (µg/l) 6.68 2.69

PEC

PNEC> 1 (risk of harm)

Marina data (UK monitoring program)

Conclusions• Labile copper controls toxicity in the environment not

total dissolved copper• As binding ligands (DOM, SPM) increase less copper is

present in the labile (toxic) form• Bivalves and seaweed are tolerant to copper in the real

world – we have underestimated tolerance• We have also overestimated concentrations in the real

world• There is little risk to marine species at current

concentrations in harbours, marinas and estuaries• We do however need to control inputs of waste paint to

stop the build up of copper in sediments – sensible use

Acknowledgements• Funded by the EU Antifouling Copper Task Force• Cefas team: Steve Brooks, Thi Bolam, Laura

Tolhurst, Bryn Jones Kevin Thomas, Mike Waldock, Jay LaRoche, Gary Hodgetts.

Recent Publications1. Brooks et al. 2007. The effects of dissolved organic carbon on the toxicity of

copper to the developing embryos of the Pacific oyster, Crassostrea gigas. Environment Toxicology and Chemistry 26 (8): 1756-1763.

2. Brooks et al. 2007. Dissolved organic carbon reduces the toxicity of copper to the germlings of the macroalgae, Fucus vesiculosus. Ecotoxicology and Environmental Safety. (in press).

3. Jones & Bolam, 2007. Copper speciation survey from UK marinas, harbours and estuaries. Marine Pollution Bulletin, 54, 1127-1138.