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Memorial University of Newfoundland

Proposal seminar

BACKGROUND & GOALS

A Sticky Mess !

RESEARCH PLAN

Understanding the interactions between oil, dispersant and oceanic organic matter

RESULTS

Presented by Narimene ZOGHBI

Supervised by Uta PASSOW

Committee Members : Baiyu ZHANG

Chris PARRISH

Uta PASSOW

OIL SPILL

What happen to the oil ?

Oil Spill

The release of petroleum and hydrocarbons in marine environment due to human activity

Weathering

Fate of marine oil spill (ITOPF)

Oil reaching shorelines

Fate and response strategies

  • High cleaning cost
  • Worst environmental consequences
  • Oil persisting for multiple decades

Response

Chemical Dispersant

Blend of surfactant

molecules and solvents

DISPERSANT

by reducing the oil-water interfacial surface tension and facilitating droplet formation

enhance the natural dispersion process

Organic matter

Aggregation, fecal pellets, coagulation ...etc

ORGANIC MATTER

10–25% of the total DOM exists as a group of heterogeneous polymers called ExoPolymeric Substances (EPS) Produced by oceanic microbes

Marine Snow

Conceptual graph showing EPS, TEP and Micro-gels and their operationally-determination (Xu et al., 2019)

MARINE OIL SNOW

Marine oil Snow

Oil can get integrated into MS creating Marine oil Snow (MOS)

It can also interact with mineral particle creating oil mineral particles (OMAs)

Reduce aggregation but increase the amount of oil per aggregates ==> Bigger oil export to the seafloor

Schematic of the effects of dispersant application on the formation of sinking diatom aggregates (Passow et al.,2017)

A disaster waiting to happen

Grand Banks of Newfoundland

Project objectives

Goals and objectives

  • Study the interactions of dispersed oil with suspended organic/inorganic matter
  • understand the impact of organic matter on dispersant effectiveness
  • The respective effects on local phytoplanktonic communities.

Method development and Micro-droplets study

Chapter 1

Method development (Flow Imaging Microscopy)

  • Distinguish between chemically dispersed and other treatments
  • Test dispersant effectiveness?
  • Estimate oil concentration ?

Impacts of dispersant and organic matter on the oil droplets parameters and their distribution?

WAF and CEWAF Prep

0.1% oil

ASW

WAF and CEWAF Prep

WAF

corexit

1 hour rest at 5°C

1 hour shaking at 150 rpm at 5°C

0.1% oil

ASW

1:20 Corexit

CEWAF

3 Replicates per treatment

  • WAF : Water Accommodated Fraction
  • CEWAF : Chemically Enhanced Water Accommodated Fraction

Sampling and measures

Sampling and analysis

Flow imaging microscopy (6R/S)

  • Oil droplets number, shape , color intensity, volume..

Sampling

Dispersant effectiveness tests

Chapter 2

  • Impact of the presence of exudate on the dispersant capacity to disperse oil
  • Are those impacts consistent no matter the form of EPS or do they vary?
  • Is it possible to explain the impacts of natural DOM on the dispersant effectiveness ?

Treatements

  • GX_CEWAF Gum Xhanthan CEWAF
  • PEPS_CEWAF : Phytoplanktonic EPS CEWAF
  • BEPS_CEWAF : Bacterial EPS CEWAF
  • Bloom_CEWAF : CEWAF with Filtred Seawater (bloom)

Treatments

Conditions and set up

  • 3 Replicates per treatments
  • Oil concentration 1 mL/L
  • Dispersant to Oil ration 1:20
  • 5°C

GX_CEWAF and PEPS_CEWAF

ASW+GX

GX_CEWAF

48 h rest

1h rest

1 h shaking at 150 rpm

PEPS_CEWAF

phytoplankton culture

1h rest

Filtration

1 h shaking at 150 rpm

0.1% oil

ASW

WAF

1 hour rest at 5°C

1 hour shaking at 150 rpm at 5°C

0.1% oil

ASW

1:20 Corexit

CEWAF

ASW+GX

GX_CEWAF

48 h rest

1h rest

1 h shaking at 150 rpm

ASW+GX

GX_CEWAF

Title

48 h rest

1h rest

1 h shaking at 150 rpm

PEPS_CEWAF

phytoplankton culture

1 h shaking at 150 rpm

Filtration

1h rest

Bloom_CEWAF

1h rest

1 h shaking at 150 rpm

BEPS_CEWAF

2 h rest

1h rest

1 h shaking at 150 rpm

ASW+BEPS

BEPS_CEWAF & Bloom_CEWAF

Bloom_CEWAF

1h rest

1 h shaking at 150 rpm

SW

BEPS_CEWAF

2 h rest

1h rest

1 h shaking at 150 rpm

ASW+BEPS

Measurements

Measurements

  • EOE (estimated oil equivalent) (6R/S)
  • Oil volumetric concentration (6R/S)
  • Oil droplets parameters
  • TOC
  • EPS Polysaccharides , protein
  • TEP (6R/S)

Aggregates formation

Chapter 3

Rolling tank experiments

  • Allows aggregation by establishing solid body rotation

Conditions

  • 5 °C & 1% oil
  • 1:20 Dispersant to oil ratio
  • How does the dispersant use impact the OMAs and MOS formation (with different types of EPS)?
  • How dispersant and different types of EPS impact the partitioning of oil between dispersed droplets and aggregated phase?

OIL Mineral aggregates

OMA's

WAF + Clays Bloom_WAF CEWAF + Clays bloomCEWAF

+ Clays + Clays

3 Replicates per treatment

Composite aggregates

Composite aggregates

Proxy-CEWAF + Clays

PEPS-CEWAF + Clays

BEPS-CEWAF + Clays

Proxy-WAF + Clays

PEPS-WAF + Clays

BEPS-WAF + Clays

Diatom aggregation

Live culture CEWAF

Dead culture CEWAF

Oil live culture CEWAF

Live culture WAF

Dead culture WAF

Oil live culture WAF

Bacteria mediated MOS micro aggregate

Bacterial MOS

UV sterilized culture natural local bacteria WAF

Live local bacteria culture WAF

Oil Live local bacteria culture WAF

UV sterilized culture natural local bacteria CEWAF

Live local bacteria culture CEWAF

Oil Live local bacteria culture CEWAF

Measurement

Measurements

Surrounding sea water

  • EOE (estimated oil equivalent)
  • Oil volumetric concentration
  • Oil droplets parameters
  • EPS, TEP

Aggregates

  • Aggregates size and number
  • EOE
  • EPS, TEP
  • Sinking velocity

Communities response

Chapter 4

What are the impacts of oil and/or dispersant exposure on

  • Local phytoplankton growth and aggregation?
  • Local Diatoms EPS production?
  • Gene Expression of diatoms grown in the presence of CEWAF?

•How does the water samples collected during a bloom aggregate in presence and absence of oil and dispersant?

Treatments

Treatments

WAF CEWAF ASW Enriched

Seawater

Measurements

  • Phytoplankton physiological response (fluorometry)
  • Gene Expression (transcriptomic analysis) in collaboration with another group

FLOW IMAGING MICROSCOPY FOR OIL STUDIES

Droplets study

Pre-tests and method development

Pretests and method development

  • Creation and optimization of a protocol to study oil droplets using the Flowcam
  • Creation of an oil droplets libraries of 50236 different droplets from various treatments
  • Creation of statistical filters able to identify oil droplets in mix samples
  • Concentration of oil in the droplet phase

Micro-droplets properties distribution

Micro-droplets distribution

Micro-droplets size ( Diameter ESD) Box Plots

WAF CEWAF

DISPERSANT EFFECTIVENESS TESTS

Dispersant effectiveness

3 treatments

  • WAF
  • CEWAF
  • GX_CEWAF

TEP

EOE

Droplets Properties

Droplets

THANK YOU FOR YOUR ATTENTION

Time table

Time table

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