Acute toxicity of crude and dispersed oil to octopus pallidus (Hoyle,1885) hatchlings 原油及分散劑對章魚苗之急性毒性試驗

Sara M. Long , Douglas A. HoldwayWATER RESEARCH (2002) 36:2769-2776

Reporter: Bei-Chan Liu

Introduction

Introduction• Tanker accidents release approximately one third

of the 1.18 million metric tonnes of petroleum hydrocarbons that enter the aquatic environment worldwide each year.

• Example:• The Exxon Valdez in Alaska in 1989• The Sea Empress in Pembrokeshire in 1996• 2001年台灣阿瑪斯號• 2005年台灣宜蘭吉尼號

Clean-up method

In situ buring Chemical dispersants

Determining the best techniqueto employ

Sea swelland wind and wave

intensity

The organismsHabitat type of the surrounding areas

Composition of the oil

The extent of the slick

Oil spill

The Sea Empress oil spill

Octopus pallidus

O. pallidus is a common species of octopus that ranges from the central Great Australian Bight to central NewSouth Wales.

Methods

• Octopus traps were laid off the coast at Portarlington,Port Phillip Bay,Victoria, at a depth of 14m, in April 1998.

•The majority of females had laid eggs in their traps; the remaining females laid eggs whilst captured.

Water-accommodated fraction (WAF)

The lab-experiments are designed to be relevant both for produced water releases as well as for oily exposed water created in oil spill situations.

.

WAF Dispersed-WAF One part Bass Strait crude oil was mixed with nine parts 5 μm filtered

seawater (vortex of no more than 25% of the solution) in a 20L glass mixing chamber for 23 h, and then left to settle for an hour.

Dispersed-WAF was prepared the same way as WAF except dispersant (Corexit 9527) was added immediately after the oil at a ratio of

1:50 (dispersant:oil) ,stirred for 23 h and allowed to settle for 1h.

Gas Chromatography

Determine total petroleum hydrocarbon (TPH) concentration

WAF

Ten recently hatched (24–96 h post hatch)

O. pallidus

Dispersed-WAF

Mortality was recorded daily.

Controltank

Twenty recently hatched (24–96 h post hatch)

O. pallidus

24h 50% Lethal Concentration (LC50):24小時半數致死濃度

濃度效應曲線

No observable effects concentration (NOEC)無觀察效應濃度lowest observable effect

concentration (LOEC)最低觀察效應濃度

• Toxicity studies were also conducted using

4-chlorophenol as a reference toxicant.

• Analysis of 4-chlorophenol was based on the method described by Clesceri et al.

Phenolic compounds

4-aminoantipyrine

At PH7.9

Potassium ferricyanide

At room temperature for 15 min.

500nm measure

Results

10-fold

Below the limit of detection

Di spersed-WAF' s l owermol ecul ar wei ghthydrocarbons rate

3%

97%

WAF' s l ower mol ecul arwei ght hydrocarbons rate

30%

70%

O. pallidus hatchlings were more sensitive to exposure to WAF alone compared to dispersed-WAF.

Younger hatchlings were more sensitive to exposure than older hatchlings in dispersed-WAF for both the 24 and 48 h-LC50.

Discussion

Toxicity tests

Dispersed-WAF was significantly less toxic than WAF alone to O. pallidus hatchlings.

WAF Dispersed-WAF

48-h LC50 0.39 1.8

O. Pallidus hatchlings

Hydra viridissima (Mitchell et.al)

WAF Dispersed-WAF

96-h LC50 0.7 9.0

Dispersed-WAF was significantly less toxic than WAF.

The CV increasing from 14 to 68.

WAF was highly toxic to O. pallidus hatchlings over the first 24 h of exposure, compared to dispersed-WAF.

A study showed that there was no significant increase in 96-h and 7-day LC50 values of fathead minnow exposed to benzene. The lethal effect of benzene upon the fathead minnow occurred mostly in the first days of exposure.

Chemical analysis

Addition of dispersants

TPH concentration

WAF Dispersed-WAF

7.07ppm 73.73ppm×10

Dispersed-WAF

Increasing in the heavier, lesswater-soluble hydrocarbons, such as PAHs( 多環碳氫化合物 ).

PAHs•The higher molecular weight •low acute toxicity

Low aqueous solubility

Bass Strait crude oil

•Light crude oil,•The water-soluble aromatic hydrocarbons account for up to 45% of total hydrocarbons

Di spersed-WAF' s l owermol ecul ar wei ghthydrocarbons rate

3%

97%

WAF' s l ower mol ecul arwei ght hydrocarbons rate

30%

70%

Addition of Corexit 9527 resulted in 1.An increase in the TPH present in the

solution.

2. No increase in the toxic,lower molecular weight hydrocarbons.

Effect of age upon toxicity

The digestive glands in O. pallidus hatchlings in the present study may not have had the ability to metabolise petroleum hydrocarbons.

Sensitivity of O. pallidus to toxicants

4-chlorophenol

O. pallidus

Ceriodaphnia dubia

D. magna

48-h LC50 0.14ppm 9ppm 6ppm

NOEC 0.33ppm 0.2ppm 2.6ppm

Difference in sensitivity may also be as a result of using early life stages in the present study as well as species sensitivity.

Conclusions

• Petroleum hydrocarbons present in the water column after addition of chemical dispersants were not in the form that was toxic to, in this case, O. pallidus.

• The lower molecular weight hydrocarbons, the concentration of which was not increased by addition of Corexit 9527, may be the more toxic components of WAF alone.

• Application of chemical dispersants to an oil spill is unlikely to adversely affect O. pallidus and possibly other benthic species.

Thank you

for

your attention