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Toxicity of Aromatics

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  • Sediment Toxicityof

    Petroleum Hydrocarbon Fractions

    Preparedfor

    Massachusetts Department of Environmental ProtectionOffice of Research and Standards

    1 Winter Street8th Floor

    Boston, MA 02108

    Preparedby

    BATTELLE397 Washington StreetDuxbury, MA 02332

    September 2007

  • Sediment Toxicity of Petroleum Hydrocarbon Fractions September 2007

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  • Sediment Toxicity of Petroleum Hydrocarbon Fractions September 2007

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    EXECUTIVE SUMMARY

    There is a recognized need by regulatory agencies, such as the Massachusetts Department ofEnvironmental Protection (MADEP) for the development of petroleum cleanup goals in sedimentthat are protective of aquatic receptors. This is due to the close proximity of many petroleum-contaminated sites to marine or fresh surface waters where petroleum products that have beenreleased to the environment may reach the surface water and sediment, adversely affectingaquatic receptors. The first step toward developing cleanup goals is identifying toxicity-basedsediment benchmarks.

    The proposed approach for the development of sediment benchmarks is based on a methodologythat divides the individual hydrocarbons from petroleum into several classes or groupings ofcompounds referred to as fractions, with similar chemical and toxicological properties. Fouraliphatic and four aromatic fractions were chosen for the development of sediment benchmarksfor the protection of aquatic receptors. Current MADEP analytical methods for petroleum insediments, however, divide the hydrocarbons into different fractions based on human health risk.It is recommended that the existing MADEP methods be closely reviewed and methodmodifications be considered and evaluated, which will enable revised versions of those methodsto be applied to sediment characterization for ecological risk.

    The approach described in this report for estimating the acute and chronic toxicity of hydrocarbonfractions to aquatic organisms is based on equilibrium partitioning (EqP) theory. This theorystates that the toxicity of hydrocarbons in sediments to benthic organisms is caused by thehydrocarbons that partition from the organic fraction of sediment particles into porewater andfrom porewater into the tissues of sediment-dwelling organisms. Both bioaccumulation andtoxicity of hydrocarbons increase as the octanol-water partition coefficient (Kow) of thehydrocarbon increases. A regression of toxicity data versus Log Kow produces a straight line fromwhich toxicities of other hydrocarbons can be estimated if their Log Kows are known. Using thefinal chronic aquatic toxicity value, the sediment organic carbon/water partition coefficient (Koc),and the fraction of organic carbon in sediment, equilibrium partitioning sediment benchmarkswere derived for the four aliphatic and four aromatic hydrocarbon fractions of petroleum (TableES-1). For comparison, sediment benchmarks were also derived based on the carbon fractionscurrently used by MADEP (Table ES-2).

  • Sediment Toxicity of Petroleum Hydrocarbon Fractions September 2007

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    Table ES-1. Sediment Benchmarks for Recommended Petroleum Hydrocarbon Fractions

    HydrocarbonFraction

    GeometricMean

    Log KowKoc

    Final ChronicValue(g/L)

    SedimentBenchmark(mg/kg oc)

    SedimentBenchmark(foc = 0.001)

    (mg/kg)Aliphatic HydrocarbonsC5 C8 4.12 7.24 x 103 218 1591 1.59C9 C12 6.01 4.37 x 105 6.3 2722 2.72C13 C18 8.57 1.10 x 108 0.05 a 5543 5.54C19 C36 11.64 8.32 x 1010 0.0001a 9883 9.88Aromatic HydrocarbonsC6 C8 2.82 4.47 x 102 1191 531 0.53C9 C12 3.94 4.90 x 103 46.2 228 0.23C13 C15 4.67 2.40 x 104 5.2 125 0.13C16 C24 5.9 3.39 x 105 0.12a 40 0.04a The fraction is not likely toxic because mean LC50 exceeds mean aqueous solubility.

    Table ES-2. Sediment Benchmarks for Current MADEP Petroleum HydrocarbonFractions

    HydrocarbonFraction

    GeometricMean

    Log KowKoc

    Final ChronicValue(g/L)

    SedimentBenchmark(mg/kg oc)

    SedimentBenchmark(foc = 0.001)

    (mg/kg)Aliphatic HydrocarbonsC5 C8 4.12 7.24 x 103 218 1591 1.59C9 C18 7.32 7.41 x 106 0.4 3167 3.17C19 C36 11.64 8.32 x 1010 0.0001a 9883 9.88Aromatic HydrocarbonsC9 C10 3.84 3.98 x 103 59.4 236 0.24C11 C22 4.81 3.31 x 104 2.8 92 0.09a The fraction is not likely toxic because mean LC50 exceeds mean aqueous solubility.

    Various uncertainties in using the equilibrium partitioning approach to develop sedimentbenchmarks for petroleum are presented. These include the various methods for estimating Kowand the resulting Kow values; the limited amount of toxicity data for aliphatic hydrocarbons; thewide range of aromatic hydrocarbon toxicity data for both marine and freshwater species, as wellas various test durations; and the selection of the most appropriate application factor, which isapplied to account for differences in acute and chronic toxicity values and species sensitivity.These uncertainties were addressed in an appropriately conservative manner consistent withprevious work by Hansen et al. (2003), DiToro et al. (1991), Total Petroleum HydrocarbonCriteria Working Group (TPHCWG) (1997), and the European Community (EC) (2003).

  • Sediment Toxicity of Petroleum Hydrocarbon Fractions September 2007

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    TABLE OF CONTENTS

    1.0 Introduction .........................................................................................................................11.1 Objectives ...................................................................................................................... 11.2 Petroleum Hydrocarbons................................................................................................ 2

    1.2.1 Composition .......................................................................................................... 21.2.2 Fractionation.......................................................................................................... 31.2.3 Analytical Methods ............................................................................................... 5

    2.0 Conceptual Site Model ........................................................................................................92.1 Fates of Petroleum Products .......................................................................................... 92.2 Equilibrium Partitioning .............................................................................................. 102.3 Toxicity ........................................................................................................................ 122.4 Toxicological Data....................................................................................................... 13

    3.0 Derivation of Risk-based Sediment Benchmarks..............................................................153.1 Derivation of the Aquatic Toxicity Value.................................................................... 153.2 Derivation of the Application Factor (AF)................................................................... 203.3 Calculating Sediment Benchmarks .............................................................................. 203.4 Application of Sediment Benchmarks ......................................................................... 223.5 Uncertainties ................................................................................................................ 23

    4.0 References .........................................................................................................................25

    TABLES

    Table ES1. Sediment Benchmarks for Recommended Petroleum Hydrocarbon Fractions ........ivTable ES2. Sediment Benchmarks for Current MADEP Petroleum Hydrocarbon Fractions ......ivTable 1. Comparison of Different Hydrocarbon Fractions to Characterize Risk...........................4Table 2. Solubility, Mean Log LC50s, and Log Kows for Aliphatic Hydrocarbons Used to

    Form the Regression Equation .......................................................................................15Table 3. Solubility, Mean Log LC50s, and Log Kows for Aromatic Hydrocarbons Used to

    Form the Regression Equation .......................................................................................16Table 4. Geometric Mean Acute Aquatic Toxicity (LC50) Values for Four Aliphatic

    Hydrocarbon Fractions...................................................................................................18Table 5. Geometric Mean Acute Aquatic Toxicity (LC50) Values for Four Aromatic

    Hydrocarbon Fractions...................................................................................................19Table 6. Sediment Benchmarks for Recommended Petroleum Hydrocarbon Fractions..............22Table 7. Sediment Benchmarks for Current MADEP Petroleum Hydrocarbon Fractions...........23

    FIGURES

    Figure 1. Molecular Structure of Several Aromatic and Aliphatic Hydrocarbons Found inPetroleum. ....................................................................................................................... 3

    Figure 2. Partitioning of Hydrocarbons in Sediment.................................................................... 10Figure 3. Equilibrium Partitioning Conceptual Site Model.......................................................... 12Figure 4. Regression of Log LC50 verses Log Kow for Aromatic Hydrocarbons .......................... 17

  • Sediment Toxicity of Petroleum Hydrocarbon Fractions September 2007

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    Figure 5. Regression of Log LC50 verses Log Kow for Aliphatic Hydrocarbons ........................... 17

    APPENDICES

    Appendix A: Toxicological DataAppendix B: Calculation Spreadsheets

  • Sediment Toxicity of Petroleum Hydrocarbon Fractions September

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