1、EFFECTS OF OIL AND CHEMICALLY DISPERSED OIL IN THE ENVIRONMENT HEALTH AND ENVIRONMENTAL SCIENCES DEPARTMENT PUBLICATION NUMBER 4693 PREPARED UNDER CONTRACT BY: J.N. BOYD, J.H. KUCKLICK, D.K. SCHOLZ, A. H. WALKER, R.G. POND, AND A. BOSTROM SCIENTIFIC AND ENVIRONMENTAL ASSOCIATES, INC. CAPE CHARLES, V
2、IRGINIA MAY 2001 American Petroleum Institute Effects of Oil and Chemically Dispersed Oil in the Environment Health and Environmental Sciences Department API PUBLICATION NUMBER 4693 - PREPARED UNDER CONTRACT BY: J.N. BOYD, J.H. KUCKLICK, D.K. SCHOLZ, A.H. WALKER, R.G. POND, AND A. BOSTROM SCIENTIFIC
3、 AND ENVIRONMENTAL ASSOCIATES, INC I CAPE CHARLES, VIRGINIA MAY 200 1 BACKGROUND ON THIS BOOKLET SERIES Beginning in 1994, the Marine Spill Response Corporation (MSRC), and later the Marine Preservation Association (MPA), sponsored a study to examine the reasons for the apparent differences between
4、expert and non expert perceptions of dispersant use and the ecological effects of dispersant use. Using a prescribed risk communication methodology, this study compared the mental models (an individuals thought processes in making a decision regarding a particular issue) of US dispersant decision-ma
5、kers and other stakeholders to an expert model (expert consensus of the relevant decision concepts that might be used), specifically looking at the fate and effect of spilled oil in comparison to chemically-dispersed oil. Through a series of interviews and written questionnaires, a number of dispers
6、ant misperceptions were identified. These misperceptions were translated into topics for booklets that would provide dispersant information in a concise and reader-fnendly format. For more information on the MSRChPA study, please see Bostrom et al., 1995, Bostrom et al., 1997, and Pond et al., 1997.
7、 As a result of the MSRCMPA work, in 1996, the American Petroleum Institute (API) commissioned the preparation of three dispersant-related booklets: Fate of Spilled Oil in Marine Waters: Where Does It Go? What Does It Do? How Do Dispersants Affect It? An Information Booklet for Decision Makers. A De
8、cision-Makers Guide to Dispersants: A Review of the Theory and Operational Requirements. Effects of Oil and Chemically Dispersed Oil in the Environment.* *This booklet is the third in the series. In the previous two booklets it was referenced by a draft title - Defining the Links Between Fate and Tr
9、ansport Processes with Exposure and Effects of Oil and Chemically Dispersed Oil in the Environment.” TABLE OF CONTENTS Paae Overview .xi Purpose of Booklet 1 Introduction . 1 Part I: Sources of Contamination and Injury 2 Section I: What is Oil? 2 Section II: What is a Dispersant? . 5 Part n: Toxicit
10、y and Exposure 5 Section I: Toxicity 5 Section II: Exposure . 7 Section III: Routes of Exposure . 9 Part III: Effects of Oil and Chemically Dispersed Oil 14 Section I: Potential Effects . 14 Section II: Effects of Untreated Oil 16 Section III: Effects of Chemically Dispersed Oil . 24 Section IV: Spi
11、ll Studies of Undispersed Versus Dispersed Oil . Discussion of Field Test Results 32 Part IV Examining Tradeoffs and Conducting a Risk Assessmen 36 In Review . 38 References and Further Reading . 41 LIST OF TABLES Table Paae 1 Comparison of Oil Properties for Several Commonly Used Refined Oil Produc
12、ts . 4 2 3 Relative Toxicity of Substances .7 How Tainting Occurs .23 OVERVIEW e e The American Petroleum Institute commissioned the preparation of three booklets to help bridge the gap in the understanding of dispersant use, effectiveness, and effects. This third booklet focuses on exposure and eff
13、ects of untreated oil and chemically dispersed oil in the marine environment. Crude oil is a complex, highly variable mixture of hydrocarbons and other trace compounds. Exposure may cause a variety of adverse effects, including narcosis, slowed growth, reduced reproduction, and death. Dispersants ar
14、e mixtures of chemicals known as solvents and surfactants. Solvents reduce the viscosity of both the oil and the dispersant, and help surfactants penetrate into the oil. The surfactants then help the oil break up and disperse into the water column. Toxicity is the “inherent potential or capacity of
15、a material (in this case, oil or dispersed oil) to cause adverse effects in living organisms”. To be toxic, oil components must be bioavailable to the organisms being exposed. Many of the components in oil are considered toxic, but have limited bioavailability in the environment. Toxic effects depen
16、d on the duration of exposure, and the concentration of the chemical(s) involved. Concentrations of chemicals and oil are often measured in parts-per-million (ppm) or parts-per-billion (ppb). To quanti toxicity data, endpoints are often expressed in terms of the concentration necessary to kill 50% o
17、f the test organisms over a specified time perod (LC50) or the concentration necessary to cause a particular effect in 50% of the test organisms over a specified period of time (EC50). Toxic effects can be lethal (causing death) and sublethal (e.g., disorientation, reduced growth and reproduction).
18、Toxic effects can also be acute (caused by short-term exposure) or chronic (caused by long-term exposure). The amount of oil exposure an organism will experience depends on many factors, including: 1. Oil type 2. Spill volume 3. Shoreline type 4. Tide stage 5. Weather conditions There are four main
19、routes of exposure for organisms during a spill: 1. Direct contact - an organism contacts or becomes coated with a substance. 2. Ingestion - an organism eats or drinks a substance. 3. Inhalation - an organism inhales a substance in the form of a vapor, mist, or spray. 4. Absorption - an organism abs
20、orbs a substance directly through its skin or respiratory membranes. Afier oil is spilled, it typically undergoes eight main fate and weathering processes, which may all occur simultaneously in different degrees: 1. 2. 3. 4. 5. 6. 7. 8. Spreading and advection - When spilled, oil spreads out on the
21、surface of the water. This increases the surface area of the oil, thus increasing the potential for exposure by all routes. Evaporation - Many components of oil evaporate. This creates a vapor that can lead to inhalation of toxic compounds as they pass From the water surface to the atmosphere. Disso
22、lution - Some components of the oil will go into solution in the surrounding water. This increases the chance of exposure through direct contact, ingestion, or absorption for water column resources. Natural dispersion - Oil breaks up into droplets in the water beneath the slick and may float away. A
23、s a result, water column resources can be exposed through direct contact, ingestion, and absorption. Emulsification - Oil and water combine to form a mousse. Exposures can result From direct contact or ingestion. Photo-oxidation - Sunlight transforms some oil components into new by- products, which
24、may be more toxic and water-soluble than the original components. Water surface and water column resources can be exposed to the by- products through inhalation, direct contact, absorption, and ingestion. Sedimentation and shoreline stranding - Oil washes ashore and also sinks after sticking to part
25、icles in the water. Exposure can occur through direct contact and ingestion of stranded or sunken oil. Biodegradation - Oil is slowly broken down by resident bacteria into H20 and CO2. Biodegradation is a slow process, with little effect on exposures. Different resources are at varying risk of expos
26、ure to untreated oil and chemically dispersed oil. These resources are discussed in the following groups: 1. 2. Surface-dwelling resources - This typically includes birds, marine mammals, and reptiles. These resources are at high risk of exposure to oil floating on the surface during a spill. Water
27、column (pelagic) resources - This group includes fish and plankton. They are typically at lower risk of exposure to oil during a spill. Dispersion can temporarily increase the risk of exposure to these resources. 3. 4. Bottom-dwelling (benthic) resources - This includes all resources that live on, o
28、r in, the bottom. Typical examples are many species of crabs, bivalves, and plants. They are usually at lower risk of exposure during a crude oil spill and are most affected by sinking oil. Intertidal resources - These resources live in the areas that are exposed to air during low tides, but submerg
29、ed during high tides. They also include many species of crabs, bivalves, and plants. If a spill reaches the shore, these resources are at high risk of exposure, as successive layers of oil can be put down by tides and winds. Bioaccumulation and biomagnification of hydrocarbons are not believed to be
30、 of great concern to vertebrates (fish, mammals, etc.) since they are able to metabolize them. Some invertebrates, however, have limited, if any, capability to metabolize hydrocarbons (e.g., shellfish). Long term contaminated shellfish may be able to eliminate (depurate) hydrocarbons over time if th
31、ey can be placed in uncontaminated waters. The effects (if any) of oil on these organisms have not been clearly established. Tainting (the presence of an “off-taste” or smell in seafood) is a concern after a spill. Tainting cannot be easily tested. Tainting will cause the greatest problems in shellf
32、ish, which have a limited, if any, ability to metabolize hydrocarbons. Finfish can metabolize the oil within several days after exposure ends. Field tests and spill studies on dispersant use have generally found that the use of dispersants has some drawbacks and may increase adverse effects to some
33、resources in the short-term. However, this can be outweighed by the immediate and longer-tem beneficial effects to other resources that can result from dispersant use. Dispersants and chemically dispersed oil will affect different resources in different ways, depending on the exposure conditions and
34、 the manner in which the dispersants are used. The potential environmental benefits and impacts of dispersant use tradeoffs among resources should always be carefully weighed. To minimize adverse effects on water column resources, dispersant use in waters less than 10 meters deep, in bays, or in are
35、as with low flushing rates has historically been avoided. However, dispersant use need not be ruled out automatically. In these areas, dispersant use should be examined and compared to other response options in order to determine the optimal response in terms of net environmental benefit. The respon
36、se method providing the greatest net environmental benefit should be the determining factor in these areas. Ecological risk assessments enable the methodical comparison of ecological tradeoffs of various response methods. Ecological risk assessments should be part of pre-spill planning activities to
37、 speed the decision-making process for possible dispersant use during actual incidents. INTRODUCTION Consider this scenario - an oil tanker has been involved in an accident near mangroves and a large salt marsh. Some of the tankers cargo has been released in the accident. One member from the team of
38、 decision- makers is assigned the responsibility of recommending countermeasure options. While dispersants are one option, he is concerned about their possible effect on resources in the area, including all resident plants and animals. Many papers are available which provide information on the diffe
39、rent effects of chemically dispersed oil on biological resources. However, applying the findings from numerous scientific experiments to a real-world emergency is not easy. What this person wants is a con- cise booklet that in laymans terms explains the general effects of oil and chemically disperse
40、d oil on various biological resources. Such a booklet would have made preparing for, and now dealing with, dispers- ant use issues less time consuming, while making the information more comprehensible. This booklet was designed to fill that planning need. Ideally, it should be read along with other
41、reference material as part of pre-spill planning activities, not just during a response emergency. PURPOSE OF THE BOOKLET This booklet has been developed as a reference document for oil spill response decision-makers, to provide an accurate summary of exposure and effects of oil and chemically dispe
42、rsed oil in the marine environ- ment. During both pre-spill planning and actual response, decision- makers are faced with many questions concerning exposure and effects. For instance: What will the oil do to a particular biological resource, both to individuals and the entire population? Is dispersa
43、nt alone likely to cause adverse effects? Will adding chemical dispersants change the way oil affects plants and animals? Would it be better to expose one resource to the oil so that another resource could be protected? These are the types of questions addressed in this booklet. Part One of the book
44、let provides a general, background discussion on concepts necessary for understanding the potential sources of oil and dispersed oil contamination that can cause adverse effects. This infor- 1 Purpose of Pad I, Section I To review oil composition and properties. Hydrocarbons are chemi- cal compounds
45、 composed solely of carbon and hydrogen atoms. In crude oils, hydrocar- bons are the most abundant compounds-up to 85 percent of the overall mixfure (Gilfi/lan, 1993). mation provides the foundation for understanding oil chemistry, toxic- ity, and exposure. Part Two focuses on the effects of undispe
46、rsed oil and Part Three discusses how chemically dispersing oil changes expo- sure and effects to marine animals and plants. Resources are discussed in groups, according to their distribution in the environment and their likelihood of exposure to oil and chemically dispersed oil (Le., surface- dwell
47、ing, water column, bottom-dwelling , and intertidal). Part Four provides information on the tradeoffs of various decisions and informa- tion on conducting an ecological risk assessment. This booklet also identifies and explains specific terms associated with oil that may be used by technical experts
48、 during planning or response operations. The first time a new technical term is used within this book- let, it will appear in an ALL CAPS format; this signifies that a more detailed explanation or definition is present in the right or left margin near where the word(s) is first used within the main
49、text. PART I: SOURCES OF CONTAMINATION AND INJURY The type of oil spilled is a key variable in determining its impact on a biological resource. The composition of crude oil is different from re- fined products, and both compositions can vary greatly. For instance, one crude oil may have many components that evaporate quickly into the atmosphere, whereas, another crude oil may be composed of many heavy components that can persist in the environment for a long time. General oil properties are reviewed below. A more detailed discussion on oil chemistry can be found in the first booklet i
