Bioremediation of Relcalcitrant Compounds - Chapter 2 doc

11 chapter two Toxicological exposure of bound recalcitrant compounds Herbert Fredrickson, John S. Furey, and Jeffrey W. Talley Contents 2.1 Introduction 11 2.2 Bioavailability of recalcitrant compounds and environmental risk assessment 12 2.3 Equilibrium partitioning and sediment quality guidelines 14 2.4 Recalcitrant compounds in sediments 15 2.5 Effects of diagenesis and weathering on recalcitrant compound geosorbents 17 2.6 K oc -based predictions 18 2.7 New protocols 20 2.8 Microbial degradation recalcitrant compounds in sediment 22 2.9 Thermal desorption mass spectrometry of recalcitrant compounds 23 2.10 Conclusions 26 References 26 2.1 Introduction This chapter relates the importance of the toxicological exposure potential of recalcitrant compounds in sediments and dredged material to implemen- tation of public laws and regulations governing environmental risk assess- ment; summarizes recent peer-reviewed literature on sediment recalcitrant L1656_C002.fm Page 11 Wednesday, July 6, 2005 7:51 AM © 2006 by Taylor & Francis Group, LLC 12 Bioremediation of Recalcitrant Compounds compounds’ exposure potential in the context of microbial degradation and the sorbant quality of sediment organic carbon; and introduces the practical utility of thermal desorption mass spectrometry with respect to identification and quantification of recalcitrant compounds, measuring recalcitrant com- pounds’ release energy, and the compatibility of the development of field-portable direct-sampling analytical technologies. 2.2 Bioavailability of recalcitrant compounds and environmental risk assessment The Clean Water Act (Section 404 of PL 92-500) and the Marine Protection, Research, and Sanctuaries Act (also known as the Ocean Dumping Act, Section 103 of PL 92-532) require that sediment-associated contaminants be evaluated for their ability to accumulate in biota. Jointly, the U.S. Army Corps of Engineers (USACE) and the U.S. Environmental Protection Agency (EPA) adopted a tiered system to evaluate this bioaccumulation potential ( Imple- mentation Manual for Section 103 , a.k.a. the Green Book , and Implementation Manual for Section 404 , a.k.a. Inland Manual ). Definitive bioaccumulation tests require that three different organisms be exposed to sediment for 28 days and then the recalcitrant compounds’ body burdens determined using stan- dard analytical techniques. From a practical perspective, it is not feasible to test all sediments and dredged material the USACE must manage. It is also apparent that noncontaminated sediments do not warrant bioaccumulation testing, and some sediments are so contaminated that bioaccumulation is a foregone conclusion. The EPA/USACE testing manuals describe a screening level protocol termed thermodynamic bioaccumulation potential (TBP) (McFar- land, 1995). TBP has been widely used in tier 2 evaluations to exclude from further testing sediments from both extremes of the contamination level continuum. TBP predicts the partitioning behavior of recalcitrant compounds between sediment organic carbon and benthic organism lipid. TBP is based on a thermodynamic model (Mackay, 1982) of the environment as a system composed of various compartments where contaminants have come to equi- librium though passive processes. At equilibrium, fugacity (i.e., escaping tendency) is equal in all sorptive and solution phases (Mackay, 1991). On the basis of fugacity, it is possible to predict the equilibrium distribution of a nonpolar contaminant between any two phases. The two most relevant phases with respect to the bioaccumulation of recalcitrant compounds from contaminated sediment are sediment organic matter and organism lipid. The sorption of recalcitrant compounds to sediments has been simply but elegantly described. Karickhoff et al. (1979) combined thermodynamic theory (i.e., fugacity) (Mackay, 1979) with empirical correlations to derive a systematic procedure for predicting contaminant sediment sorptive behav- ior. In spite of the “high degree of variability and complexity in sediment composition and large number of potential sorptive interactions,” Karickhoff L1656_C002.fm Page 12 Wednesday, July 6, 2005 7:51 AM © 2006 by Taylor & Francis Group, LLC Chapter two: Toxicological exposure of bound recalcitrant compounds 13 intentionally developed a simple mathematical format that required a min- imum of measured parameters. He felt a balance must be struck between a complex model few could afford to parameterize and the degree of accuracy and precision required in its application (Karickhoff et al., 1979). Karickhoff showed that for neutral hydrophobic contaminants (i.e., water solubilities less than 10 –3 M ), sorption isotherms in the low loading limit are linear and reversible. Their partition coefficients (K p ) were highly correlated to the organic carbon content of the soils/sediments in this data set. Referencing sorption to organic carbon content produced a partition coefficient to organic carbon (K oc ) that was independent of other bulk sediment/soil parameters. Karickhoff’s (1981) “justifiable simplification” found even wider application when he showed that K oc could be directly derived from the contaminants’ octanol–water partition coefficients. Concurrently, Könemann and van Leeuwen (1980) showed a linear rela- tionship between K oc and the partitioning of a series of chlorobenezenes from sediments to lipid normalized benthic infaunal biomass. McFarland (1984) synthesized information from Karickhoff and Könemann and van Leeuwen and derived a relationship for TBP (McFarland and Clarke, 1986): TBP = AF(C S /f OC )f L where AF = accumulation factor C S = recalcitrant compound concentration in whole sediment f OC = decimal fraction of organic carbon in sediment f L = decimal fraction of lipid in targeted organism Biota-sediment accumulation factors (BSAFs) have also been empirically determined and used to describe the distribution of recalcitrant compounds between lipid normalized biomass and organic carbon normalized sediment. BSAF = (C T /f L )/(C S /f OC ) where C T /f L = the lipid normalized contaminant tissue concentration C S /f OC = the organic carbon normalized contaminant sediment concentration Initial TBP predictions, derived from an arbitrarily fixed AF of 4, were shown to consistently overestimate polycyclic aromatic hydrocarbon (PAH) bioaccumulation from contaminated sediments by factors ranging between 41 and 386 (McFarland, 1995). Precision and accuracy of TBP predictions were improved to a factor of 10 when empirically derived BSAFs from one field reference sediment contaminated with PAH were used to calculate TPB for a second field sediment contaminated with PAH (Clarke and McFarland, L1656_C002.fm Page 13 Wednesday, July 6, 2005 7:51 AM © 2006 by Taylor & Francis Group, LLC 14 Bioremediation of Recalcitrant Compounds 2000). That is, field reference–derived BSAFs were substituted for AFs in the original TBP equation. Clarke and McFarland (2000) concluded that TBP was a useful screening tool for eliminating sediments with negligible likelihood of causing unacceptable bioaccumulation from further testing and tended to generally overestimate recalcitrant compounds’ bioaccumulation from sediment. 2.3 Equilibrium partitioning and sediment quality guidelines In the absence of site-specific information, environmental managers must use the best available information, and this often entails the use of model predictions to support sediment management decisions. To this end, the logic of Karickhoff’s fugacity-based model of recalcitrant compounds–sediment partition coefficients K p normalized to organic carbon content K oc has been combined with that of TBP to predict benthic marcofauna exposure levels (Figure 2.1). Predicted exposure levels are subsequently interpreted in the context of aquatic toxicity databases. This equilibrium partitioning (EqP)-based logic is the basis for deriving sediment quality criteria as pro- posed by DiToro et al. (1991). TBP predictions of bioaccumulation potentials and EqP estimates of exposure potentials are both derived from K oc . The accuracy, precision, and general applicability of predictions made on the basis of K oc -predicted recal- citrant compounds–sediment–pore water equilibrium partitioning have been debated in the technical literature since it was first proposed. The practical ecological and economic consequences of this issue have escalated as appli- cations of the K oc model have expanded beyond that of a sediment screening Figure 2.1 Equilibrium partitioning (EqP) as described by DiToro et al. (1991) is predicated on a model that assumes that equilibrium exists between the contaminant sorbed to sediment organic carbon, pore water, and lipid of benthic biota. The par- titioning of recalcitrant compounds between sediment organic matter and pore water is predicted from K oc (Karickhoff, 1981). Biota Sediment Carbon Pore Water K oc L1656_C002.fm Page 14 Wednesday, July 6, 2005 7:51 AM © 2006 by Taylor & Francis Group, LLC Chapter two: Toxicological exposure of bound recalcitrant compounds 15 tool. Some suggest that EqP-derived predictions combined with aquatic toxicity databases can be used as stand-alone pass/fail predictors of sedi- ment quality whose implementation can be modeled after EPA’s Water Qual- ity Criteria. A review of this issue is beyond the scope of this chapter. The reader is referred to articles promoting the use of EqP model predictions in sediment management decisions (DiToro et al., 1991; Ankley et al., 1996; Burkhard, 2000) and those that argue for more limited use of the models in sediment management decisions (Iannuzzi et al., 1995; Driscoll and Lan- drum, 1997; O’Connor et al., 1998; van Beelen et al., 2001; Condor et al., 2002). Instead, we will focus the remainder of this discussion on technical issues relevant to two factors that can have major effects on the dosage of recalcitrant compounds realized by benthic macrofauna that are not addressed in K oc -based TBP or EqP models: recalcitrant compounds’ seques- tration in sediment and microbial degradation of recalcitrant compounds in sediment. 2.4 Recalcitrant compounds in sediments Luthy et al. (1997) characterized matter in soils and sediments as geosor- bents. Soils and sediments are heterogeneous at the scale of samples, aggre- gates, and particles. Structurally or chemically different constituents of sed- iments interact differently with recalcitrant compounds in terms of binding energies and associated rates of sorption and desorption. Complex assem- blages of the components can cause complex mass transfer phenomena. The term sequestration refers to some combination of diffusion limitation, adsorp- tion, and partitioning. Sorption and desorption rates for recalcitrant com- pounds in geosorbents occur on timescales ranging from fast (e.g., minutes to days) to slow (e.g., weeks to years). Although their relative proportions vary greatly, most recalcitrant compounds’ contaminated sediments to date have both rapidly and slowly desorbing recalcitrant compound fractions. Desorption rate differences are thought to be due to processes such as intra-aggregate diffusion, releases from micropores, or different forms of geosorbent organic matter. Two of these proposed geosorbant domains, soft amorphous organic matter and soot, have been shown to be particularly important when attempting to predict recalcitrant compounds’ equilibrium partitioning and, ultimately, exposure and toxicity. Decaying plant material (case A in Figure 2.2) is a major source of sediment organic matter and a major food source for detritivores. This low-density fraction of sediment organic matter from a New York–New Jersey estuary contained 10 times the level of PAH pre- dicted by organic carbon normalized equilibrium partition coefficients (K oc ) (Rockne et al., 2002). This fraction readily released PAH into the aqueous phase and was the controlling factor in whole-sediment PAH release. Drift- ing plant detritus has also been shown to be a major contributor to the total annual load of organochlorine contaminants (including polychlorinated biphenyl (PCB)) in the Detroit River (Lovett-Doust et al., 2002). These recent L1656_C002.fm Page 15 Wednesday, July 6, 2005 7:51 AM © 2006 by Taylor & Francis Group, LLC 16 Bioremediation of Recalcitrant Compounds studies are especially important. They demonstrate that plant detritus, a major food source at the base of aquatic food webs, can be the major con- tributor to recalcitrant compounds’ theoretical maximium daily loads, and K oc significantly underestimates the bioaccumulation of recalcitrant com- pounds from this trophodynamically important geosorbant. In this common aquatic environmental situation, K oc -based environmental risk predictions (i.e., TBP, EqP, and sediment quality criteria) would not be protective. K oc -derived predictions of bioaccumulation and toxicity of sediments containing soot (case B in Figure 2.2) have also been shown to be inaccurate. Socha and Carpenter (1987) compared PAH-contaminated sediments from two sites within Puget Sound. K oc -predicted pore water PAH levels agreed with empirically determined pore water PAH levels (within a factor of 4) at a creosote-impacted site. However, no PAH was detected in sediment pore water from a site impacted by combustion products and natural PAH, even though detectable levels were predicted using K oc . McGroddy and Far- rington (1995) published similar results on PAH-contaminated sediments in Boston Harbor. Pore water PAH levels were depleted relative to those pre- dicted using K oc . Variances for individual PAHs varied, but only 0.2 to 5.0% of K oc -predicted phenanthrene was actually measured in sediment pore water. PAH associated with pyrogenically derived soot particles was sug- gested as the reason for the discrepancies (McGroddy et al., 1996). Paine et al. (1996) showed that heavily PAH-contaminated sediments (highest levels of 10,000 mg/kg and mean levels of 150 mg/kg) from Kitimat Arm, at the head of Douglas Channel in British Columbia, did not change benthic com- munity structure, were not toxic to benthic fauna, and generally did not accumulate in the commercially important Dungeness crab. Most of the PAH in this sediment originated from the washout of a wet air scrubber from Figure 2.2 Conceptual model of distribution of hydrophobic organic chemicals in sediment. rap = rapidly desorbing compartment; slow = slowly desorbing compart- ment; K oc,rap = partition coefficient between rapidly desorbing compartment and pore water (l/kg organic carbon); BCF = bioconcentration factor (l/kg lipid). (From Kraaij, R., Sequestration and Bioavailability of Hydrophobic Chemicals in Sediment, Ph.D. dissertation, University of Utrecht, Netherlands, http://www.library.uu.nl/digiar- chief/dip/diss/1960191/inhoud.htm) Deposit-Feeder (Lipid) Pore Water K oc, rap Rap BCF Slow Sediment (Organic Carbon) L1656_C002.fm Page 16 Wednesday, July 6, 2005 7:51 AM © 2006 by Taylor & Francis Group, LLC Chapter two: Toxicological exposure of bound recalcitrant compounds 17 aluminum smelter potlines. Aluminum smelter–derived PAH in sediments from Sunndalsfjord, Norway (Naes and Oug, 1998 and Naes et al., 1999) were present at lower levels (15 mg/kg) than Kitmat sediment but were likewise not biologically available because they were associated with soot particles. Song et al. (2002) showed that black carbon constituted between 18 and 41% of the total organic carbon of soil and sediment samples collected from Guang- zhou, China. The percentage of soot in any particular series of sediment sam- ples can be highly variable due to variability in air and water currents, which deposit them in aquatic systems, and sediment particle segregation, resuspen- sion, redistribution, and transport by episodic water currents. 2.5 Effects of diagenesis and weathering on recalcitrant compound geosorbents In addition to the sources of sediment organic matter (e.g., vascular plants, algae), diagenesis and weathering affect sediment quality characteristics that are correlated to rates of recalcitrant compounds’ sorption and desorp- tion (Luthy et al., 1997). Some diagenetically aged organic matter (e.g., coal and shale) exhibits a high degree of condensation, is reduced in the relative amount of oxygen-containing functional groups (reflected in H/O and O/ C atomic ratios), and contains more aromatic carbon rings (measure by ultraviolet (UV) and infrared (IR) absorbance). This reduced organic matter Figure 2.3 The recalcitrant compound pore water pool is probably the most biolog- ically available. Kraaij’s (2002) conceptual model (modified above) equates recalci- trant compound in pore water to the rapidly desorbing fraction of recalcitrant compounds from sediment organic matter. Part of the pore water recalcitrant com- pounds can be taken up into benthic macrofaunal lipid. However, neither Kraaij’s conceptual model nor most of those currently proposed take into consideration the ability of sedimentary bacterial communities to mineralize recalcitrant compounds. The factors that determine this partitioning of the pore water recalcitrant compounds’ pool between macrofaunal lipid and microbial mineralization are not well under- stood. Pore Water CO 2 Deposit-Feeder (Lipid) Sediment (Organic Carbon) Bioconcentration Factor Microbial Degradation K oc, rapid Rapid Slow L1656_C002.fm Page 17 Wednesday, July 6, 2005 7:51 AM © 2006 by Taylor & Francis Group, LLC 18 Bioremediation of Recalcitrant Compounds has been characterized as hard or glassy. Glassy organic matter strongly binds recalcitrant compounds (Brannon et al., 1998) and is characterized by slow mass transfer rates and nonlinear adsorption kinetics (Haitzer et al., 1999; LeBoeuf and Weber, 2000). Kerogen is another organic matter fraction that has undergone diagenic alterations that has been shown to have non- linear recalcitrant compounds’ sorption isotherms and high capacity to bind recalcitrant compounds (Song et al., 2002). Little is known about the distri- bution of kerogen in surface sediments in the context of sequestering recal- citrant compounds. A portion of kerogen and other organic material can also be dissolved in pore water in a form that is not removed by filtration (Gauthier et al., 1987) and thus greatly affects the pore water recalcitrant compound concentrations and mechanisms of recalcitrant compounds’ bio- accumulation. This emerging technical information on the sorption behavior of recal- citrant compounds with respect to the quality of sediment organic carbon can directly affect the USACE management of dredged materials. Soxhlet-extractable PAH levels in dredged material from a confined disposal facility at Milwaukee Harbor (Table 2.1) averaged 115 mg/kg, but only 46 mg/kg (i.e., less than half) was readily biologically available for either micro- bial degradation (Ringelberg et al., 2001) or bioaccumulation in earthworms (Talley et al., 2002). The empirically determined BSAF for total PAH accu- mulation from Milwaukee Harbor–dredged material into the earthworm ( Eisenia fetida ) was 0.08. Five percent of the dry weight mass of Milwaukee Harbor-dredged material was coal/coke. Sixty percent of the total extractable PAHs were associated with this coal/coke fraction, and almost none of it was biologically available. As a consequence, the potential for bioremedia- tion to reduce the total extractable PAH from this dredged material is limited (Myers et al., 2002). 2.6 K oc -based predictions Appropriate use and informed interpretation of the data derived from screening tools are essential for effective sediment management. Sediments have been described in which K oc -based predictions of bioaccumulation and toxicity have been inaccurate. Thus, the universal application of K oc -based predictions without reasoned judgment in interpretating the resulting pre- dictions can lead to both significant under- and overassessments of environ- mental risk. Karickhoff’s “justifiable simplification” will be an even more useful screening tool when its limits of applicability are more fully under- stood and appreciated. The environmental distribution and relative abun- dance of organic matter that sequesters recalcitrant compounds in sediment, and the fate of recalcitrant compounds when desorbed from this material, are currently not known but warrant further study. To gain this perspective, we present and discuss additional tests and environmental parameters that will improve assessments of recalcitrant compound bioaccumulation poten- tial from sediments. L1656_C002.fm Page 18 Wednesday, July 6, 2005 7:51 AM © 2006 by Taylor & Francis Group, LLC Chapter two: Toxicological exposure of bound recalcitrant compounds 19 Table 2.1 Summary of PAH Level in Two Density Fractions (Silt/Clay and Coal) of the Milwaukee Harbor CDF-Dredged Material, the Sequestration Energy Measured by Thermal Desorption Mass Spectrometry, the Rapidly Desorbed Fraction (Tenax), and the Bioaccumulation by Earthworms and Microbial Biodegradation Potential (Talley et al., 2002) Measures of PAH Availability Fraction of Milwaukee CDF-Dredged Material % Dry Wt. of Dredged Material Total PAH Level (mg/kg) Sequestration Energy Sorption of RC to Tenax Earthworm Uptake Biodegradation Potential Silt/Clay 95% 80–100 <40% Low >85% High High Coal 5% 10,000 >60% High <5% Low Low L1656_C002.fm Page 19 Wednesday, July 6, 2005 7:51 AM © 2006 by Taylor & Francis Group, LLC 20 Bioremediation of Recalcitrant Compounds 2.7 New protocols A number of new sediment testing protocols have recently been published that are designed to produce better information on recalcitrant compounds’ sediment–pore water partitioning, bioaccumulation potential, exposure potential, and toxicity. These approaches have been reviewed from a toxico- logical perspective (Condor et al., 2002). In evaluating these approaches, it is important to realize that whereas some of them are designed to provide better information on the chemical partitioning of recalcitrant compounds between sediment and pore water, others are designed to produce better data on the transfer of recalcitrant compounds from sediment into biota. All of these approaches have their respective merits and disadvantages. For example, Kelsey and Alexander (1997) compared mild solvent extractions (e.g., butanol) to contaminant bioaccumulation. Although the procedure was simple and fast, no single solvent extraction system produced a reasonable correlation to empirically measured BASF when different soils and test organisms were used. Weston and Maruya (2002) have suggested that stom- ach fluids from deposit-feeding animals are an appropriate extraction fluid for benthic animals that accumulate contaminants via their digestional tracks. Standardizing this assay presents some technical challenges, and it may not be the most appropriate approach for hydrophobic/lipophilic con- taminants that are also taken up through the skin and gills. Concurrent USACE Long Term Effects of Dredging Operations (LEDO) work units led by Dr. Jim Brannon, Dr. Vic McFarland, and Dr. Todd Bridges are focused on evaluating these approaches. Karickhoff’s (1979) original assumption was that pore water was the major exposure pathway associated with sediments and derived K oc as a means to predict recalcitrant compounds’ levels in pore water. The low volume of pore water recoverable from most sediments, coupled with the low levels of recalcitrant compounds in most pore waters, presents an ana- lytical challenge with respect to recalcitrant compound detection limits and the precision and accuracy of the data. A series of studies has shown that the rapidly desorbing fraction of sediment-bound recalcitrant compounds was the most likely to become accumulated into biomass (Landrum, 1989; Robertson and Alexander, 1996, 1998; Tang et al., 1998; Cornelissen et al., 1998; Rockne et al., 2002; Kraaij et al., 2002; McGroddy et al., 1996; Talley et al., 2002; Weber et al., 2002). Kraaij et al. (2002) demonstrated that pore water recalcitrant compound concentration was a far superior predictor of bioac- cumulation potential than levels of recalcitrant compounds extractable with organic solvent from the bulk sediments (Figure 2.4). Kraaij’s prediction method is independent of bulk sediment measures. This approach shows promise because it is a simple model that also appears to accurately predict recalcitrant compounds’ bioaccumulation potential. A number of analytical solutions based on solid phase extraction tech- nologies have been proposed to measure the rapidly desorbed recalcitrant compounds’ fraction, if not the actual recalcitrant compounds’ pore water L1656_C002.fm Page 20 Wednesday, July 6, 2005 7:51 AM © 2006 by Taylor & Francis Group, LLC [...]... indicative of the amount of a particular recalcitrant compound thermally desorbed from the sediment The thermal desorption profile (Figure 2. 5) shows the heat energy required to © 20 06 by Taylor & Francis Group, LLC benzo(b)fluoranthene, benzo(k)fluoranthene, and benzo(a)pyrene Ti-MW2 02 Ti-MW2 52 Ti-MW276 fluoranthene and pyrene 0.005 R4Tf-MW2 02 R4Tf-MW2 52 0.004 R4Tf-MW276 0.003 0.0 02 0.001 0 0 50 100 150 20 0 25 0... the basis of mass Ions of known mass are detected using an electron multiplier L1656_C0 02. fm Page 21 Wednesday, July 6, 20 05 7:51 AM Ball Valve Toxicological exposure of bound recalcitrant compounds Spring Clip Thermocouple Chapter two: Flared Sample Vial Heater Coil L1656_C0 02. fm Page 22 Wednesday, July 6, 20 05 7:51 AM 22 Bioremediation of Recalcitrant Compounds levels Cornelissen et al (20 01) developed... Application of Sediment Quality Guidelines Protective of Effects through Bioaccumulation Proceedings of 20 02 SETAC Pellston Workshop: Use of Sediment Quality Guidelines (SQGs) and Related Tools for the Assessment of Contaminated Sediments, SETAC 20 04 © 20 06 by Taylor & Francis Group, LLC L1656_C0 02. fm Page 27 Wednesday, July 6, 20 05 7:51 AM Chapter two: Toxicological exposure of bound recalcitrant compounds 27 ... Istok, J.D 1994 Effects of rate-limited desorption on the feasibility of in situ bioremediation Water Resour Res 30: 24 13 24 22 Garbarini, D.R and Lion, L.W 1986 Influence of the nature of soil organics on sorption of toluene and trichloroethylene Environ Sci Technol 20 : 126 3– 126 9 Gauthier, T.D., Seitz, W.R., and Grant, C.L 1987 Effects of structural and compositional variations of dissolved humic materials... L1656_C0 02. fm Page 24 Wednesday, July 6, 20 05 7:51 AM 24 0.007 L1656_C0 02. fm Page 25 Wednesday, July 6, 20 05 7:51 AM Chapter two: Toxicological exposure of bound recalcitrant compounds 25 desorb the particular contaminant and is used to calculate sequestration energy (Talley et al., 20 02) , which is a measure of how tightly the particular recalcitrant compound is bound to the sediment In the first use of thermal... transition and enthalpic relaxation behavior Environ Sci Technol 34: 3 623 –3631 © 20 06 by Taylor & Francis Group, LLC L1656_C0 02. fm Page 29 Wednesday, July 6, 20 05 7:51 AM Chapter two: Toxicological exposure of bound recalcitrant compounds 29 Lovett-Doust, J., Lovett-Doust, L., Biernacki, M., Mal, T.K., and Lazar, R 20 02 Organic contaminant content of plant species in the Detroit River Can J Fish Sci., in press... Technol 31: 20 3 20 9 Haitzer, M., Abbt-Braun, G., Traunspurger, W., and Steinberg, C 1999 Effects of humic substances on the bioconcentration of PAHs: Correlations with spectroscopic and chemical properties of humic substances Environ Toxicol Chem 18: 27 82 27 88 Hatzinger, P.B and Alexander, M 1995 Effect of aging of chemicals in soil on their biodegradability and extractability Environ Sci Technol 29 : 537–545... P.H 1995 Comments on the use of equilibrium partitioning to establish sediment quality criteria for nonionic chemicals Environ Toxicol Chem 14: 125 7– 125 9 Johnson, M.D and Weber, W.J., Jr 20 01 Rapid prediction of long-term rates of contaminant desorption from soils and sediments Environ Toxicol Chem 35: 427 –433 Karickhoff, S.W 1981 Semi-empirical estimation of sorption of hydrophobic pollutants on natural... 20 02; Ringelberg et al., 20 01) The silt/clay low-density fraction constituted 95% of the dry weight of the dredged material and contained less than 40% of the Soxhlet-extractable PAH The majority of this fraction’s PAHs were biodegradable by microorganisms and could be taken up by earthworms The higher-density coal-derived fraction constituted 5% of the dredged material dry mass, but more than 60% of. .. Group, LLC L1656_C0 02. fm Page 23 Wednesday, July 6, 20 05 7:51 AM Chapter two: Toxicological exposure of bound recalcitrant compounds 23 be mainly a function of the fast desorption rate on the supply side and the rate of microbial degradation and partitioning into benthic infaunal lipid on the sink side Recalcitrant compounds in the rapidly desorbing fraction may overwhelm the capacity of microorganisms . height. 0 0.001 0.0 02 0.003 0.004 0.005 0.006 0.007 050100 150 20 0 25 0 300 350 400 Temperature (°C) Normalized Ion Count Ti-MW2 02 Ti-MW2 52 Ti-MW276 R4Tf-MW2 02 R4Tf-MW2 52 R4Tf-MW276 fluoranthene and. 17 2. 6 K oc -based predictions 18 2. 7 New protocols 20 2. 8 Microbial degradation recalcitrant compounds in sediment 22 2. 9 Thermal desorption mass spectrometry of recalcitrant compounds 23 2. 10. Coil ermocouple Spring Clip Flared Sample Vial L1656_C0 02. fm Page 21 Wednesday, July 6, 20 05 7:51 AM © 20 06 by Taylor & Francis Group, LLC 22 Bioremediation of Recalcitrant Compounds levels. Cornelissen et al. (20 01) developed