Analysis of the underwater emissions from outboard engines

This thesis compares the emissions from a two-stroke outboard engine when using an EAL and an equivalent mineral lubricant, where the primary objective of the study is to characterise an

AN ALY SI S OF THE

This thesis is submitted for the award of the degree of Doctor of Philosophy,

in the School of Mechanical, Manufacturing and Medical Engineering,

Queensland University Technology, Brisbane, Australia

April 2004

Research on the subject of outboard engine emissions has continued at QUT after the examination of this thesis As a result a gross error factor of 655 was discovered Essentially, each concentration with normalised

concentration (ug/kWhr) should be increased by the above factor A paper with the corrected results has been submitted to an international journal The error does not effect the relative comparison made between emissions in the thesis nor the statistical analysis However, comparison with other emission results or emission guidelines does require the correction to be applied

The development of Environmentally Adapted Lubricants (EALs) and their use has been gaining momentum over the last decade It has been shown that raw EALs degrade in the environment in about one tenth the time of an equivalent mineral based lubricant Estimates and findings such as these serve to highlight the potential benefits of the EAL products, it is also important however to investigate the by- products of their use to ensure that the benefits are not cancelled by an increase of, for instance, combustion by-products This thesis compares the emissions from a two-stroke outboard engine when using an EAL and an equivalent mineral lubricant, where the primary objective of the study is to characterise and quantify the pollutants that remain within the water column after combustion To accomplish this, tests were conducted both in the laboratory (freshwater) and in the field (seawater) for a range of throttle settings A 1.9kW two-stroke outboard engine was set-up in a test tank and water samples were taken from the tank after the engine had been run for a period at each of the throttle settings The tests were repeated for a 5.9kW four-stroke engine, however, the experiments were only conducted in the laboratory (freshwater) and using only a standard mineral lubricant Statistical analyses of the results were conducted using a Principal Components Analysis (PCA) A simple dilution model was used to estimate the initial outboard engine emission concentrations, which was extended to determine the concentrations at distances of 1, 10 and 100 metres from the source An investigation of the Total Toxicity Equivalence of the PAH pollutant concentrations (TEQ PAH ) was conducted using Toxicity Equivalent Factors (TEFs) Results for both types of engine and in both fresh and seawater showed that even the initial concentrations at the source, in almost all instances, were well below the ANZECC water quality guidelines trigger levels At a distance of 1 metre from the source all concentrations were well below, and therefore, the Total Toxicity Equivalents of the PAHs were found to be even lower It is concluded that the emissions from a single outboard engine when using either an EAL or a mineral based lubricant are similar However, the use of EALs has further reaching advantages in that spilt raw lubricants will degrade in the environment up to 10 times faster than a mineral lubricant Also EALs are less toxic

to aquatic and marine organisms and therefore the benefits of using them has to be viewed from a wider perspective The results in this thesis for a single outboard engine now form the basis for a more detailed environmental assessment of their impacts

A BSTRACT I

T ABLE OF C ONTENTS II

L IST OF F IGURES VI

L IST OF T ABLES IX

N OMENCLATURE XI

A CRONYMS XIII

P UBLICATIONS A RISING FROM THE P ROJECT XV

A CKNOWLEDGEMENTS XVI

S IGNED S TATEMENT XVIII

CHAPTER 1 1

I NTRODUCTION 1

1.1 Background 1

1.2 Aims and Objectives of the Project 4

CHAPTER 2 6

L ITERATURE R EVIEW 6

2.1 Background 6

2.2 The Two-Stroke Engine 9

2.2.1 How a Two-Stroke Engine Works 9

2.2.2 Advantages and Disadvantages of Two-Stroke Engines 10

2.3 Tribology 11

2.3.1 General Characteristics of Petroleum 12

2.3.2 Types of Petroleum Products 12

2.3.3 Gasolines and Lubricating Oils 13

2.3.4 The General Fate of Hydrocarbons in the Marine Environment 14

2.3.5 The Fuel/Oil Mixture as a Pollutant 15

2.3.5.1 Polycyclic Aromatic Hydrocarbons 15

2.3.5.2 Volatile Organic Compounds 28

2.3.6 Environmentally Adapted Lubricants 31

2.4 Previous Studies Related to Marine Engine Testing 33

2.4.1 European Studies 34

2.4.2 Studies in the USA 36

2.4.3 Australian Studies 39

2.4.4 Limitations within the Previous Studies 39

2.5 Engine Performance Modelling 42

2.6.1.1 Principal Components Analysis 47

CHAPTER 3 50

E QUIPMENT AND M ETHODOLOGIES 50

3.1 Experimental Equipment and Set-Up – Engines 50

3.2 Fuel Consumption Tests 61

3.2.1 Procedure 61

3.3 Preliminary Pollutant Investigation 62

3.3.1 Equipment and Procedure 62

3.4 Two – Stroke Engine Laboratory Tests 64

3.4.1 Equipment and Procedure 64

3.5 Two – Stroke Engine Field Tests 65

3.5.1 Field Test Site 65

3.5.2 Field Test Equipment and Procedure 66

3.6 Four – Stroke Engine Tests 67

3.6.1 Equipment 67

3.6.2 Procedure 67

3.7 PAH Identification and Quantification 67

3.7.1 Preparation of the Water Samples for Analysis 67

3.7.2 Extraction Procedure 68

3.7.3 Sample Analysis 69

3.7.4 Efficiency of the Extraction Procedure 70

3.7.5 Calculations 70

3.8 VOC Identification and Quantification 73

3.9 Raw Fuel and Oil Analyses 73

3.10 Engine Performance Modelling 73

3.11 Statistical Analysis 97

CHAPTER 4 98

R ESULTS 98

4.1 Fuel Consumption Tests 99

4.1.1 Two-Stroke Engine FC Tests – Laboratory 99

4.1.2 Two-Stroke Engine FC Tests – Field 100

4.1.3 Four-Stroke Engine FC Tests – Laboratory 101

4.2 Preliminary Pollutant Investigation Results 101

4.3 Raw Fuel and Oil Results 102

4.4 Two - Stroke Engine Laboratory Test Results – PAHs 104

4.5 Two - Stroke Engine Laboratory Test Results – VOCs 107

4.6 Two - Stroke Engine Field Test Results – PAHs 108

4.7 Four - Stroke Engine Laboratory Results – PAHs 110

4.8 Four - Stroke Engine Laboratory Results – VOCs 110

4.9 Two-Stroke Engine Performance Modelling 111

4.9 General Discussion 114

CHAPTER 5 117

P OLYCYCLIC A ROMATIC H YDROCARBONS A NALYSIS FOR THE T WO -S TROKE E NGINE 117

5.1 Mineral vs EAL Laboratory Tests PAH Results 118

5.2 Mineral vs EAL Field Tests PAH Results 121

5.3 Fresh Water vs Sea Water PAH Results - Mineral Oil 124

5.4 Fresh Water vs Sea Water PAH Results – EAL 126

5.5 General Discussion 128

CHAPTER 6 130

V OLATILE O RGANIC C OMPOUNDS A NALYSIS FOR THE T WO -S TROKE E NGINE 130

6.1 Mineral vs EAL Laboratory Tests VOC Results 131

6.2 General Discussion 133

CHAPTER 7 135

C OMPARISON OF THE T WO -S TROKE AND F OUR -S TROKE E NGINE E MISSIONS 135

7.1 PAH Results for the Two and Four Stroke Engines 136

7.2 VOC Results for the Two and Four Stroke Engines 139

7.3 General Discussion 141

CHAPTER 8 144

P OLLUTANT D ILUTIONS 144

8.1 Dilution of the Fresh Water Laboratory PAH Results 147

8.2 Dilution of the Fresh Water Laboratory VOC Results 148

8.3 Dilution of the Sea Water PAH Results 149

8.4 Dilution of the Four-Stroke Engine Test Results 151

8.5 Two and Four-Stroke Engine Dilutions Comparisons 152

8.6 General Discussion 155

CHAPTER 9 157

T OXICITY OF THE P OLLUTANTS 157

9.1 General Discussion 160

CHAPTER 10 162

C ONCLUSIONS AND F UTURE R ESEARCH 162

10.1 Conclusions 162

10.2 Future Research 164

REFERENCES 167

APPENDIX A – RESULTS OF THE PRELIMINARY POLLUTANT INVESTIGATION 172

APPENDIX D: TWO-STROKE ENGINE PERFORMANCE MODELLING INPUT DATA 183 APPENDIX E: POWER AND TORQUE DATA FOR THE HONDA OUTBOARD ENGINE 187

Figure 1: Diagrammatical Representation of the Naphthalene Molecule 15

Figure 2: Diagrammatical Representation of the Anthracene and Phenanthrene Molecules 16

Figure 3: Diagram of the Heavier PAH Molecules Pyrene and Benzo(a)pyrene 16

Figure 4: An Underwater Image of the Exhaust Gases being emitted from the Hub of an Outboard Engine's Propeller 41

Figure 5: Test Tank Tap 51

Figure 6: Fuel Line Modifications (Rea, 2001) 54

Figure 7: Two-Stroke Outboard Engine Test Rig - Rear View 55

Figure 8: Two-Stroke Outboard Engine Test Rig - Front View 55

Figure 9: Carburettor Throttle Pin Travel (Rea, 2001) 56

Figure 10: Throttle Setting Gauges (Rea, 2001) 57

Figure 11: Warm-Up Stand (Rea, 2001) 58

Figure 12: Set-up of the Four-Stroke Engine Experimental Equipment for the Fuel Consumption and Engine Tests 59

Figure 13: Four-Stroke Engine Throttle Settings on Tiller Arm – Side View 60

Figure 14: Four-Stroke Engine Throttle Settings on Tiller Arm – Top View 60

Figure 15: Four-stroke Engine Warm-up Configuration 61

Figure 16: Set-up of the Two-Stroke Engine on a Small Timber Boat that was used for the In - Field Fuel Consumption Tests 62

Figure 17: Shows the Location of the Test Site 66

Figure 18: On Site Field Experiments in Progress 67

Figure 19: The Dismantled Two-Stroke Engine ready for Component Measurement 74

Figure 20: Engine Configuration Data Box 75

Figure 21: Basic Engine Dimension Data Box 76

Figure 22: Ignition and Combustion Details Data Box 77

Figure 23: Comparison of Output Power at Different Ignition Timing 79

Figure 24: Ambient Condition Data Box 79

Figure 27: Run Parameters Data Box 86

Figure 28: Inlet Valve Detail Data Box 88

Figure 29: Image of the Reed Petal and Stop Plate 89

Figure 30: Transfer Port Data Box 90

Figure 31: The Axial Attitude Angle 90

Figure 32: The Radial Attitude Angle 91

Figure 33: Exhaust Port Data Box 92

Figure 34: Diagram of a Typical Inlet Duct with Reed Valve 93

Figure 35: Inlet Duct Data Box 94

Figure 36: Transfer 1 Duct Data Box 94

Figure 37: Exhaust Pipe and Box Muffler Data Box 95

Figure 38: Exhaust System of the Outboard Engine 96

Figure 39: the Power Curve Developed by the MOTA Software after the Modelling Exercise was Undertaken 112

Figure 40: Differences Between the Results of the Actual and Modelled Fuel Consumption Rates for the Two-Stroke Engine 113

Figure 41: PCA Graph for the Comparison of the Lab Two-Stroke Engine Tests – Mineral vs EAL121 Figure 42: PCA Graph for the Comparison of the Field Test Results – Mineral vs EAL 123

Figure 43: PCA Graph for the Comparison of the Laboratory and Field Test Results – Mineral Oil 125

Figure 44: PCA Graph for the Comparison of the Laboratory and Field Test Results – EAL 127

Figure 45: PCA Graph for the Comparison of the Laboratory VOC Results 132

Figure 46: PCA Graph for the Comparison of the PAHs from both Engines 137

Figure 47: A Comparison of the Total PAH Emissions from the Two and Four-Stroke Engines 138

Figure 48: A Comparison of the Total VOC Emissions from the Two and Four-Stroke Engines 140

Figure 49: Comparison of the Brake Specific Fuel Consumption for the Two and Four-Stroke Engines 141

Figure 50: A Schematic of the Two-Stroke Engine Cycle (Rea 2001) 141

Figure 51: Shows the Decay Rate for the Pollutant Concentrations with Distance from the Propeller 146

Figure 52: The Concentrations of the Total PAH Pollutants at 100% Throttle vs Distance from the

Source 152

Figure 53: The Concentrations of the Total VOC Pollutants at 100% Throttle vs Distance from the Source 153

Figure 54: Outboard Engine Passing Velocity Measuring Probe 154

Figure 55: Velocity Disturbance Caused by an Outboard Engine in Open Water 154

Figure 56: A Comparison of the TEQ PAH between the Two and Four-Stroke Engines 160

Table 1: Principle Petroleum Fractions from Fractional Distillation 13

Table 2: Carcinogenic Potential of the Sixteen USEPA Priority PAH Pollutants 17

Table 3: USEPA PAH Priority Pollutants and their Australian Water Quality Guideline Trigger Levels 19

Table 4: The Range of VOC Pollutants Identified and their Australian Water Quality Guidelines Trigger Levels 29

Table 5: Test Tank Volume Calibration 52

Table 6: Two-Stroke Engine Fuel Consumption Tests Conducted in the Laboratory 99

Table 7: Two-Stroke Engine RPM Tests Conducted in the Laboratory 100

Table 8: Two-Stroke Engine Fuel Consumption Tests Conducted in the Field 100

Table 9: Two-Stroke Engine RPM Readings Conducted in the Field 100

Table 10: Fuel Consumption Rates at the Throttle Various Settings for the Four-Stroke Engine 101

Table 11: Engine RPM at the Various Throttle Settings for the Four-Stroke Engine 101

Table 12: Summary of the Preliminary PAH Results 102

Table 13: Summary of the Preliminary VOC Results 102

Table 14: PAH Pollutants in the Raw Fuel and Oils, and in the Fuel and Oil Mixtures 103

Table 15: VOC Pollutants in the Raw Fuel and Oils, and in the Fuel and Oil Mixtures 104

Table 16: PAH Pollutants Analysis when the Mineral Lubricant was used in the Laboratory Tests 105 Table 17: PAH Pollutants Analysis when the EAL was used in the Laboratory Tests 106

Table 18: VOC Pollutants Analysis when the Mineral Lubricant was used in the Laboratory Tests 107 Table 19: VOC Pollutants Analysis when the EAL was used in the Laboratory Tank Tests 108

Table 20: PAH Pollutants Analysis when the Mineral Lubricant was used for the Field Tests 109

Table 21: PAH Pollutants Analysis when the EAL was used for the Field Tests 109

Table 22: PAH Pollutants Analysis for the Four-Stroke Engine Tests Conducted in the Laboratory 110 Table 23: VOC Pollutants Analysis for the Four-Stroke Engine Tests Conducted in the Laboratory 111 Table 24: Final Power Output Values used to Perform the Calculations for each of the Throttle Settings and Both Lubricants 113

Table 25: Emission Rates of the PAH Pollutants when using both Lubricants - Laboratory Tests 118

Table 26: Emission Rates of the PAH Pollutants when using both Lubricants - Field Tests 122

Table 27: Emission Rates of the PAHs when using the Mineral Lubricant – Laboratory vs Field Tests

124

Table 28: Emission Rates of the PAHs when using the EAL – Laboratory vs Field Tests 126

Table 29: Emission Rates of the VOC Pollutants when using both Lubricants - Laboratory Tests 131

Table 30: Emission Rates of the PAHs from both the Two and Four-Stroke Engines 136

Table 31: Emission Rates of the VOCs from both the Two and Four-Stroke Engines 139

Table 32: Initial Concentrations of the PAH Pollutants for the Two-Stroke Engine Tests in the Laboratory when using the Mineral Oil 147

Table 33: Initial Concentrations of the PAH Pollutants for the Two-Stroke Engine Tests in the Laboratory when using the EAL 148

Table 34: Initial Concentrations of the VOC Pollutants for the Two-Stroke Engine Tests in the Laboratory when using the Mineral Oil 148

Table 35: Initial Concentrations of the VOC Pollutants for the Two-Stroke Engine Tests in the Laboratory when using the EAL 149

Table 36: Initial Concentrations of the PAH Pollutants for the Two-Stroke Engine Tests in the Field when using the Mineral Oil 150

Table 37: Initial Concentrations of the PAH Pollutants for the Two-Stroke Engine Tests in the Field when using the EAL 150

Table 38: Initial Concentrations of the PAH Pollutants for the Four-Stroke Engine Tests 151

Table 39: Initial Concentrations of the VOC Pollutants for the Four-Stroke Engine Tests 151

Table 40: The Different TEFs used by (Eljarrat et al., 2001), and used in this Study 158

Table 41: The Calculated TEQ PAH using the Different TEFs and for the Two and Four-Stroke Engines and the Fresh and Seawater Results 159

A Disc area of the propeller (m 2 )

•

C μg of pollutant emitted relevant to a particular sized engine per

second

C actual Actual concentration in the test tank (μg/L)

C& Actual concentration in the test sample (μg/mL)

n

E& Emission rate of particular pollutant at a particular throttle setting

(μg/kW.hr)

s

•

re cov

Pwr Engine output power at the particular throttle setting (kW)

V extract Volume of the extracted sample (mL)

V sample Volume of the water sample taken from the test tank (mL)

d

x

Down stream location divided by propeller diameter

ADV Acoustic Doppler Velicometer

LLINCWA Loss Lubrication in Inland and Coastal Water Activities Project

TDC Top Dead Centre

Kelly, C A., Brown, R J., Rae, D., Scott, W and Hargreaves, D (2001), A

Comparison of Mineral and Biodegradable Marine Two-Stroke Lubricants, In 2nd

World Tribology Congress, Vienna, Austria

Kelly, C A., Rasul, M and Brown, R J (2001), Characterisation of Marine

Two-Stroke Outboard Engine Emissions to Water, In 6th World Congress of Chemical

Engineering, Melbourne, Australia

Kelly, C A., Brown, R J., Ayoko, G A and Scott, W (2003), Underwater

Emissions from a Two-Stroke Outboard Engine: Can the Type of Lubricant Make

a Difference?, In National Environment Conference 2003, Brisbane, Australia

Kelly, C A., Ayoko, G A and Brown, R J (2003), Under Water Emissions from a

Two-Stroke Outboard Engine: A Comparison between an EAL and an Equivalent Mineral Lubricant, In 2nd International Conference on Tribology in Environmental

Design 2003, Bournemouth, United Kingdom

Loberto, A., Brown, RJ & Kelly, CA, (2003) A simple empirical model of

two-stroke outboard motor pollutant dispersion based on laboratory experiments of propeller dispersion Institution of Engineers Australia National Environment

Conference, 18-20 June, Brisbane

Loberto, A.R., Brown, R.J., & Kelly, C.A., 2003 Assessing environmental impacts

of two-stroke outboard motor lubricants using tank testing and simple dispersion model pp 3-12, 2nd International Conference Tribology in Environmental Design

2003, 8th-10th September 2003, Bournemouth, UK

Kelly, C A., Ayoko, G A and Brown, R J (2004), Can Environmentally Adapted

Lubricants Reduce Two-Stroke Outboard Engine Emissions?, Journal of

Environmental Science and Technology, USA (Submitted)

Kelly, C.A., Ayoko, G.A., Brown, R.J., 2004 Comparison of lubricant type and

engine configuration as factors contributing to emissions to water from outboard motors Invitation for submission of paper to special issue of Journal of Materials

and Design Invitation accepted 5th February, 2004

This thesis, while an original work by the author, would not have been possible without the assistance of many people I would first like to thank all the technical staff members of the School of Mechanical, Manufacturing and Medical Engineering here at QUT who contributed to varying degrees to the eventual completion of the research In particular, the assistance of Mr Anthony Loberto, Mr Glen Turner, Mr Bob May, Mr David McIntosh and Mr Mark Hayne was greatly valued and

appreciated A special thanks also needs to be extended to Ass Prof Doug

Hargreaves and Adj Prof Will Scott whose academic and professional guidance was invaluable

I would also like to acknowledge the contribution of Mercury Marine who kindly donated an outboard engine and a test tank for the research Likewise, Honda

Marine also donated an outboard engine and their contribution is also greatly

appreciated Another special thanks is extended to Fuchs Lubricants Australia for their kind support If not for their generosity the project would not have existed

To my associate supervisor Dr Godwin Ayoko, I express my great appreciation for his support and patience during the process of learning how to use his equipment, and for the time spent in discussion on the statistical matters of the project I also extend my great appreciation to my principal supervisor Dr Richard Brown for his support and guidance and his ability to always get the best out of myself and the

A final thankyou to my wife Melissa, daughter Laura, and son Shaun If not for the love and support you have shown over the years, I doubt that this would have been possible You have, and always will, provide me with a constant source of

inspiration, and no words of gratitude could ever truly express what your support has meant to me I love you

I hereby certify that the work embodied in this thesis is the result of original research and has not been submitted for a higher degree to any other University or Institution

To the best of my knowledge and belief, the thesis contains no material previously published or written by another person except where due reference is made in the thesis itself

_

Charles Kelly B Eng (Hons)

2006 (McFall, 2002) This has lead engine manufacturers to make design changes such as direct fuel injected two-stroke engines, or shift to the manufacture of four-stroke engines

Two-stroke engines have many advantages over four-stroke engines of a similar power; including, their simplicity and economy of manufacture, and much better power to weight ratio They are used in a wide range of applications including, but not limited to; cars, motorcycles, lawn care equipment, chainsaws and recreational boat engines Their disadvantages include; noise, and use of a total loss lubrication system

Total-loss lubricants are lubricants that are lost directly to the environment during normal use, such as; chainsaw bar and chain oil, railroad flange oils and greases, drip oils, wire rope lubricants, dust suppressants, marine lubricants, and two-stroke

engine oils (Nelson, 2000a) Among this group of lubricants, two-stroke engine oils are unique in that they undergo a process of combustion within the cylinder of an engine

Research has found that millions of litres of unburned fuel and oil are released into marine environments each year from conventional marine two-stroke engines

(Martin, 1999) Other comparative studies between different types of two-stroke engines and four stroke engines have found that carburetted two-stroke engines emit particulate matter at rates approximately 4.5 times the rate of a fuel injected two-

stroke engine and 20-80 times the rate of a four-stroke engine (Kado et al., 2000)

A study of two-stroke lawn mowers in Newcastle, Australia, found that on average, 34% of the fuel/oil mixture short-circuited directly into the exhaust The study also estimated that in comparison to local transport sources, this type of lawn mower

contributes 5.2% of CO and 11.6% of NMHC emissions in the area (Priest et al.,

2000)

Other research has shown that, in one day’s use, a single two-stroke powered

personal water craft (Jet Ski) will emit the same amount of hydrocarbons and

nitrogen oxides to the atmosphere as a 1998 model family sedan that travels 160,000

km (Martin, 1999) Other studies have shown the hydrocarbon emissions from these

engines to not only be detrimental to water quality, but also to marine biota (Juttner

et al., 1995b, Juttner et al., 1995a, Rye et al., 2000, Tjarnlund et al., 1996, Tjarnlund

et al., 1995, USEPA, 1974, Warrington, 1999)

With the focus now on the replacement of these engines with alternatives that have significantly reduced emission rates of pollutants, the engines that already exist are being neglected A typical two-stroke engine can expect to have a life span of

emitted? The studies outlined above show that there is a need for immediate

solutions as well as the longer-term measures already adopted

As previously mentioned, total loss lubricants have been an environmental concern for some time, and will be for some time to come The challenge then is to reduce the impacts of these lubricants In the early 1980’s European lubricant

manufacturers went about developing Environmentally Adapted Lubricants (EALs)

in an effort to reduce the potential impacts of their products Their development was

in response to early environmental mandates implemented by certain European

countries They are derived from vegetable oils; with the most common being

canola, soy and sunflower, and they have been shown to be low in toxicity and

rapidly biodegradable Canola is a crop that is widely cultivated in Europe, and it is now the primary type of vegetable oil used for lubricants in the European market In particular, Germany and the Alpine region countries have spent years of research in developing the performance characteristics of canola oil (Nelson, 2000a)

Past research reports that two-stroke outboard engines were the first application of EALs, and they were an ester-based fluid with suitable ash less detergent additives and low aromatic solvents Initial tests have shown these products to have excellent

high dilution and low pollution characteristics (van der Waal et al., 1993) Viewed

from the concept of ecologically sustainable development (ESD), these products have far reaching advantages over the development of mineral based products

because they are derived from renewable resources

This study has investigated the pollutants that remain within the water column after combustion, in view of the fact that most two-stroke outboard engines emit their gases below the water line Also, a comparison of the emissions when using an EAL and an equivalent mineral oil has been conducted to investigate the difference (if any) in the amounts and diversity of pollutants emitted by an engine using these different types of oils Since two-stroke engines emit a considerable part of their fuel/oil mixture into the water, and it has been documented that the toxicity of these

emissions can persist for up to 14 days in water (Juttner et al., 1995b), it is

reasonable to expect that the EAL would minimise the adverse effects of such

emissions on aquatic ecosystems Further, the use of an EAL could reduce the

emission of hydrocarbons from two-stroke engines Another comparison of the emissions was conducted between a two-stroke engine and a four-stroke engine While past research has noted the substantial difference in the emission rates

between the two types of engine, this is the first study to compare the emissions that remain within the water column The comparative tests for the two-stroke engine were conducted both in the laboratory and in the field The comparative tests for the four-stroke engine were conducted in the laboratory and were compared to the two-stroke engine laboratory tests

1.2 Aims and Objectives of the Project

• To compare the emissions to both fresh and sea water when using both lubricants and the two-stroke engine

behind the boat using a simple dispersion model

Toxicity Equivalence Factors

CHAP TER 2

2.1 Background

The World’s Oceans are a chemical system covering 71% of the Earth’s surface, and account for 77% of the water in the hydro – geological cycle Seawater is a solution

of gas and solids containing both organic and inorganic compounds It is considered

as a sink for all the salts that are present in sediments from the weathering process of the lithosphere (Yen, 1999)

Hydrocarbon (oil) contamination poses serious threats to the marine environment This was recognised by the British Government as early as 1922, when a law was passed prohibiting the discharge of oil or oily waste in territorial waters In 1975, the U.S National Academy of Science workshop estimated that approximately 6 million tons of petroleum hydrocarbons entered the oceans yearly; 40% of which was from normal vessel operations (Yen, 1999)

Queensland Transport: Marine Pollution Section, (1989), suggested that 3.2 million metric tonnes of oil finds its way into the world’s oceans each year, with 33% being from normal vessel operations and a further 12% from tanker accidents

In 1973, Australia developed a National Plan to Combat Pollution of the Sea by Oil and Other Noxious and Hazardous Substances The objectives, today, of the

Convention on Oil Pollution Preparedness, Response and Co-operation 1990

Equally as important, the Plan aims to protect both natural and artificial (man made) environments from the adverse effects of oil pollution and minimise those effects where protection is not possible (Nelson, 2000b)

Nelson, (2000b), reported further that in 1998 the Plan was extended to cover

chemical spills Despite this, the Plan exists to combat spills of oil and chemicals from tankers; it makes no recognition of the contribution of normal vessel operations Yet, as can be seen above, figures suggest that these contributions can far exceed those of tanker spills Normal vessel operations is a broad term that encompasses a wide range of operations, including but not limited to:

For the most part, the maritime industry is well regulated in Australia with legislation

in place to control discharges from all government, tourist and other licensed

professional operators A significant area of concern however, is the emissions from recreational vessels Within Queensland alone there are 155,000 registered

recreational vessels (Queensland Department of Transport, 2001), the emissions from which are largely unregulated It should also be noted that in Queensland it is not a requirement to register a vessel that has an outboard engine smaller than four-horse

power, and that the vast majority of registered vessels are powered by two-stroke engines

Studies have shown that, in one day’s use, a single two-stroke powered personal water craft (jet ski) will emit the same amount of hydrocarbons and nitrogen oxides

to the atmosphere as a 1998 model family sedan that travels 160,000 km (Martin, 1999) Other studies overseas (discussed in more detail later) have shown the

hydrocarbon emissions from two-stroke engines to not only be detrimental to water

quality, but also to marine biota (USEPA, 1974, Warrington, 1999, Tjarnlund et al.,

1995, Tjarnlund et al., 1996, Rye et al., 2000, Juttner et al., 1995a, Juttner et al.,

Marine Science (AIMS) has been charged with the task of investigating the impacts

of these rapidly biodegradable lubricants on the sensitive marine ecosystem

AIMS conducts scientific research in all tropical Australian seas and coastal regions, and provides information and technology for its clients It is an independent

institution whose objectives are to promote the conservation and sustainable

development of Australia’s marine resources Fields of study such as Tribology,

of AIMS Therefore, FUCHS Australia Pty Ltd are sponsoring a post graduate

student at QUT (in the form of a SPIRT Grant) to conduct these necessary

components of the research

2.2 The Two-Stroke Engine

The internal combustion engine is currently the most widely used mechanical producing device; there are two main types: the two-cycle (stroke) motor and the four-cycle (stroke) motor The main difference between the two types of engine is the gas exchange process – how much fuel is being transferred This also affects the amount of power the engine can produce (Marshall, 2001)

power-The basic engine operation of a two-stroke engine consists of only two movements - the compression stroke and the combustion stroke; hence the term two-stroke motor Conversely, a four-stroke engine consists of the intake, compression, combustion and exhaust strokes (Marshall, 2001)

More specifically, two-stroke engines were named as such, because they only require two strokes of the cylinder (or one crankshaft revolution) to complete the

thermodynamic cycle - the Otto Cycle The ‘Otto’ or spark-ignition thermodynamic cycle consists of the induction, compression, expansion (power) and exhaust actions (in that order) To complete this cycle in two cylinder strokes instead of four, the engine has to execute the induction and compression processes in one stroke and the expansion and exhaust processes in the other (Marshall, 2001)

2.2.1 How a Two-Stroke Engine Works

Following is a more detailed description of the two-stroke engine cycle

At the start of the cycle, a mixture of fuel and air is first compressed in the cylinder The moment the spark plug fires, the mixture will ignite The resulting explosion (and pressure) will then drive the piston downwards This downward force will compress another fuel/ air mixture in the crankcase When the piston starts to

‘bottoms out’ (at the end of the downward cycle), the exhaust port is uncovered The pressure in the cylinder will then drive out the combusted gases from the cylinder (Marshall, 2001)

At about the same time, the intake port is uncovered The piston’s downward

movement pressurises the mixture in the crankcase, while moving from a region of high pressure to an area of lower pressure This principle ensures that a new mixture

of fuel and air rushes in to take the place left void by the exhaust, repeating the above cycle (Marshall, 2001)

2.2.2 Advantages and Disadvantages of Two-Stroke Engines

The advantages (as compared to four-stroke engines) of two-stroke engines include:

Some disadvantages of these motors include:

• Poor fuel efficiency (up to 30% of the fuel/oil mixture is exhausted either

unburned or partially burned into aquatic environments)

2.3 Tribology

An integral part of engineering is a consideration of what happens at the interface between touching components When the surface of one component moves over another, there is always a resisting frictional force If the surfaces are in close

proximity then peaks of the surface roughness (called asperities) interact, increasing friction, and may cause surface damage The primary purpose of a lubricant is to separate these contacting surfaces and thereby reduce friction and wear The science involved in the study of such processes is Tribology It encompasses the study of friction, wear, lubrication and contact mechanics (Lewis, 2001)

Within an engine, lubrication is required to reduce friction thereby minimising the wear between the moving parts It also cools the engine, allowing it to operate at safe temperatures Typically, a four-stroke engine has a lubricating system that is separate from its fuel system, whereas, a two-stroke engine often has oil mixed with its fuel so that the cylinder walls and the crankcase bearings are adequately

lubricated

Comparative exhaust emission tests between two and four-stroke engines have

consistently shown that the two-stroke version can emit up to seven times the level of

toxic pollutants for engines of the same power output (Juttner et al., 1995b, Juttner et al., 1995a, Kado et al., 2000, Mace, 2000, Priest et al., 2000) In addition, even

though they have small two-stroke engines, results show that scooters emit

equivalent amounts of pollutants to that of cars, trucks and buses due to incomplete

combustion of the fuel/lubricant mixture The scooter exhaust particulate matter (comprising mainly of polycyclic aromatic hydrocarbons) is highly mutagenic, which

is shown to be significantly dependent on the type of lubricant used in the engine

(Zhou et al., 1998), therefore, a review of the fuel/lubricant mixture is undertaken

2.3.1 General Characteristics of Petroleum

Crude petroleum and most refined petroleum products are complex mixtures of many thousands of organic compounds, with hydrocarbons usually representing more than

75 per cent of the weight of the oil The remainder is made up of various nitrogen, oxygen, and sulphur containing organic compounds, and some metals (Neff, 1979)

Nearly all petroleum compounds are non-polar and not very soluble in water The behaviour of these compounds in the environment depends on the physical and

chemical nature of the particular hydrocarbon, and these properties change as the petroleum ages and weathers (Weiner, 2000)

2.3.2 Types of Petroleum Products

Crude oil is refined into petroleum products through a process known as fractional distillation Fractional distillation is a process that separates the oil components according their boiling points Each fraction represents a group of mixtures, which have boiling points within a specific range (Weiner, 2000) Table 1 describes the principal petroleum fractions that are produced by the fractional distillation process

Table 1: Principal Petroleum Fractions from Fractional Distillation

Source: Table 5.1: Principal Petroleum Fractions from Fractional Distillation (Weiner 2000)

a The notation used gives the number range of carbon atoms in the fractional compounds; e.g C 1 – C 4

means hydrocarbon compounds containing between 1 and 4 carbon atoms.

2.3.3 Gasolines and Lubricating Oils

Of particular interest in this study are gasolines and lubricating oils Consisting mainly of aliphatic and aromatic hydrocarbons, gasolines are among the lightest

Weiner, (2000), reports that Aliphatic Hydrocarbons consist of:

bonds)

carbon atoms, and

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• Alkynes, which are unsaturated hydrocarbons having one or more triple bonded carbon atoms

Aromatic hydrocarbons are hydrocarbons based on the benzene ring as a structural unit They include monocyclic hydrocarbons such as benzene, toluene, ethyl

benzene, and xylene (the BTEX group), and polycyclic hydrocarbons such as

naphthalene and anthracene (Weiner, 2000) More generally, Weiner, (2000),

suggested that gasoline mixtures are volatile and somewhat soluble They contain a much higher percentage of the BTEX group of aromatic hydrocarbons than do other fuels, such as diesel Furthermore, they contain lower concentrations of heavier aromatics like naphthalene and anthracene than do diesel and heating fuels For this reason, the presence of BTEX is often a useful indicator of gasoline contamination (Weiner, 2000), identified lubricating oils as being composed of heavier molecular

more viscous and less soluble in water

2.3.4 The General Fate of Hydrocarbons in the Marine

Environment

When hydrocarbons are released into the marine environment, they spread on the surface of the water At the same time, components of low boiling point evaporate rapidly, entraining successively higher boiling point fractions Significant amounts

Even so, the entry of petroleum hydrocarbons into the aquatic food web has been

have been shown to interfere with chemoreceptive and reproductive processes (Yen, 1999) Martin, (1999), reported that scientists have determined that millions of litres

of unburned fuel and oil are released into marine environments each year from stroke engines This is because these engines discharge as much as 30% of their fuel/oil mixture directly into the water within their exhaust stream

two-2.3.5 The Fuel/Oil Mixture as a Pollutant

Of particular interest in this study are, the products of combustion emitted as exhaust from outboard engines and those products that are emitted as unburned components The preliminary study conducted early in the project identified the presence of

polycyclic aromatic hydrocarbons, (PAHs), and volatile organic compounds,

(VOCs), remaining in the water column after the engine had been used; these are

discussed in more detail (Kelly et al., 2001a, Kelly et al., 2001b)

As previously noted, hydrocarbons that display benzene-like properties are called aromatic; those that contain fused benzene rings are called polynuclear or Polycyclic Aromatic Hydrocarbons, (PAHs) PAHs are formed when carbon-containing

materials are incompletely burned (Baird, 1999) The simplest PAH example is

H

H

H

There are two ways an additional benzene ring can be fused to the two of the

naphthalene molecule; one results in a linear arrangement for the centres of the rings, while the other is a branched arrangement, these are displayed in Figure 2 The linear arrangement is known as anthracene and the branched (or angular)

arrangement, phenanthrene (Baird, 1999)

Figure 2: Diagrammatical Representation of the Anthracene and Phenanthrene Molecules

Neff, (1979), reported that there are two molecular weight classes of PAHs, and that they are distinguished on the basis of their physical, chemical, and biological

properties These are the lower molecular weight 2 – 3 ring aromatics as shown above, and the higher molecular weight 4 – 7 ring aromatics, an example of which is shown in Figure 3

Figure 3: Diagram of the Heavier PAH Molecules Pyrene and Benzo(a)pyrene

The low molecular weight PAHs have been shown to display acute toxicity to

(Neff, 1979) Table 2 shows the carcinogenic potential of the sixteen USEPA

priority PAH pollutants

Table 2: Carcinogenic Potential of the Sixteen USEPA Priority PAH Pollutants

Source: (Manoli et al., 1999)

Blank – not tested for human carcinogenicity

2A – Probably carcinogenic to humans

2B – Possibly carcinogenic to humans

3 – Not classifiable as to human carcinogenicity

Baird, (1999), reported that the mechanism of PAH formation during combustion is complex and difficult to fully ascertain Neff, (1979), suggested that part of the reason for this is that petroleum products from different sources vary tremendously

in the relative concentrations of the different hydrocarbon types present It is thought however, that PAHs are produced by the re-polymerisation of hydrocarbon fragments that are formed during the cracking, that is, the splitting into several parts, of larger fuel molecules in the flame The re-polymerisation reaction is thought to occur more readily under oxygen-deficient conditions, and therefore the rate of PAH formation will increase as the air:fuel ratio decreases

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PAHs are serious water pollutants (Baird, 1999) However, if the total estimated amounts of PAHs that enter the aquatic environment were evenly distributed

throughout the world’s oceans and freshwater bodies, their concentrations would be completely undetectable Yet, they are not evenly distributed Most PAHs remain relatively near their point source, and can be expected to decrease in concentration approximately logarithmically with distance from the source Thus, the majority of PAHs entering the aquatic environment are localised in rivers, estuaries, and coastal marine waters (Neff, 1979)

In the past, marine pollution by PAHs has been attributed to sources such as

creosote-treated timber from docks This source was so serious in parts of Atlantic Canada in the early 1980’s that the local lobster fisheries industry was closed down because of the high PAH levels found in the crustaceans Larger PAH molecules are thought to have played a role in the devastation of the populations of beluga whales

in the St Lawrence River, and they have also been linked to the production of liver lesions and tumours in some fish (Baird, 1999)

The United States Environmental Protection Agency (USEPA), and The Australian and New Zealand Environment and Conservation Council (ANZECC) have

recognised the potential toxic threat of PAHs within the marine environment The USEPA has identified one hundred and twenty six priority pollutants within its

Water Quality Standards, sixteen of them PAHs ANZECC has assigned trigger levels within their Water Quality Guidelines for a number of these PAH pollutants (USEPA, 1988, ANZECC, 2000); these are outlined in Table 3

Table 3: USEPA PAH Priority Pollutants and their Australian Water Quality Guideline Trigger

Levels

* = Level of protection, i.e., for naphthalene (marine water) 50 μ g/L to protect 99% of species and 120 μ g/L to protect 80% of species

A = Chemicals for which possible bioaccumulation and secondary poisoning effects should be considered

Insufficient data to derive a reliable trigger value

a = Low reliability trigger levels should only be used as an indicative interim working level until more reliable acute

and chronic toxicity data allow for the calculation of reliable guideline values (as for naphthalene)

The presence of some or all of these sixteen pollutants is taken to imply that there are actually many other pollutants present in the source These pollutants form an

aggregate substance group for which data is available A summary of each of these

sixteen compounds now follows

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Naphthalene

Naphthalene is composed of two fused benzene rings with the empirical formula of

point of 218°C, and a vapour pressure of 0.0109kPa at 25°C Naphthalene is almost insoluble in water, but is soluble in benzene, toluene, ether, and several other organic solvents Naphthalene is used as raw material in the chemical, plastics, and dye industries, and as an intermediate for the manufacture of synthetic resins, celluloid, solvents, and lubricants (Faust, 1993b)

Acenaphthene

and a molecular weight of 154.21 It is a crystalline solid with a boiling point of 279°C, a melting point of 95°C, a density of 1.189 g/mL, and a vapour pressure of 6

propanol, chloroform, benzene, and toluene Acenaphthene occurs in coal tar

produced during the high temperature carbonization or coking of coal, and is used as

a dye intermediate, in the manufacture of some plastics It is also used as an

intermediate in the manufacture of insecticides and fungicides (Faust, 1994a)

Anthracene

Anthracene is the simplest tricyclic aromatic hydrocarbon and has a chemical

a boiling point of 340°C Anthracene is soluble in a variety of organic solvents,