CONTAMINATED SOIL TO ORGANIC SORBENT
A DISSERTATION
SUBMITTED TO THE DEPARTMENT OF CIVIL AND ENVIRONMENTAL ENGINEERING AND THE COMMITTEE ON GRADUATE STUDIES
OF STANFORD UNIVERSITY
IN PARTIAL FULFILLMENT OF THE QEQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY
Trang 2INFORMATION TO USERS
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Trang 421 Ag ater
(Richard G Luthy) Principal Adviser (
I certify that I have read this dissertation and that, in my opinion, it is fully adequate in scope and quality as a dissertation for the degree of Doctor of Philosophy
phlarbec (oe tasD
(Martin Reinhard)
I certify that I have read this dissertation and that, in my opinion, it is fully adequate in scope and quality as a dissertation for the degree of Doctor of Philosophy
(Scott Fendorf)
Trang 5Polycyclic aromatic hydrocarbons (PAHs) are among those contaminants referred to as
persistent organic pollutants PAHs are compounds of great environmental concern because of
their persistency in the environment, carcinogenicity, and toxicity to humans and biota This dissertation focuses on the fate and the movement of PAHs from contaminated soil The two
key objectives of this study are to understand the relationship between PAH association with
contaminated site soil and its availability, and to provide more fundamental understandings of
mass transfer phenomena of PAHs between the soil or sediment and its surroundings in the
aspect of in-situ stabilization of the contaminant by adding organic sorbent The study includes the characterization of the contamination source, the availability of PAHs, and the mass transfer
of the compounds from the source to the surrounding environment and to a sorbent added for remediation purpose
As a case study, a soil from an automobile manufacturing plant site contaminated with PAHs was studied Various carbonaceous materials including coal, coke, pitch, and tar decanter sludge were identified by petrography and individual particle analyses Most of the PAHs were found to be associated with the polymeric mattix of tar sludge or hard pitch as discrete particles, ot as coatings on soil mineral particles, or as complex aggregates The PAH availability from
these particles was very low due to the hindered diffusive release from solid tat or pitch with
apparent diffusivities of 6x10-!5 for phenanthrene, 3x10-5 for pyrene, and 1x10-15 cm?2/s for
benzolzjpyrene Significant concentrations of PAHs were observed in the interior of solid tar
aggregates The release of PAHs from the interior of such particles would require diffusion over a substantial distance Long-term desorption tests and semi-permeable membrane device tests confirmed a very limited availability of PAHs These findings explain the results from three years of phytoremediation of the site soil, for which no significant changes in the total PAH concentrations were observed in the test plot samples
Sorption isotherms and uptake kinetics were studied for phenantherene and pyrene with
three organic model sorbents: polyoxymethylene (POM), coke, and activated carbon (AC) These
Trang 6pellets showed reasonable agreement between the independent nL2MS-measurements and the predicted intraparticle concentration profiles from kinetic batch experiments and a polymer
diffusion model For coke and AC, the uL?MS-measurements showed faster radial diffusion of
phenanthrene and pyrene into the particle interior than predicted from diffusion models For coke, this was accounted by a sorption retarded pore diffusion model with a particle size- dependent partitioning coefficient, and for AC by a branched pore kinetic diffusion model
Trang 7I did not quite understand why the graduation ceremony is called “Commencement” in
English However, standing at the end of the once-seemingly-endless and lonely journey of a Ph.D., I started to realize why
I could have not come to this far without help of so many people around me and I dedicate this page to those good Samaritans as a small token of my deepest gratitude I would
first like to thank my advisor, Professor Dick Luthy, one of the most diligent and sincere people I
have ever known Everyone around me has told me that I was a really lucky guy to have Dick as an advisor Yeah, they were darn right and I cannot agree more He has always been there when
I needed his wisdom and guidance and has welcomed my endless questions with his warm,
resilient and encouraging smile It has been truly my pleasure and honor to have him as my
mentor and I am proud of being one of his students
I also thank Professors Martin Reinhard and Scott Fendorf for serving as the committee
members for my dissertation Their considerate but keen and insightful comments on my
tesearch were constructive and helpful
Furthermore, [ am grateful to Dr David Werner and Ryan McGlothlin David had worked as a postdoc with Professor Luthy during my study and had a great influence in my
research I could have not written any single code of the modeling without his help I still
remember his magic fingers madly tapping on the keyboard and his serious look in a lab coat in the basement of the Terman building Ryan was a Chemistry major working on his master, and was teamed up with David and me for pL?MS work It is, however, my deepest regret that I am no longer able to express my gratitude for his tremendous help and share my joy with him He
had sacrificed his life in a war with Iraq, However, I will forever treasure the time we spent together in the lab
To the past and present Luthy group members, John, Lei, Pam, Sarah, Chris, Jeanne, Yeo-myoung, Dennis, Laura and Heather, I must reiterate that we are the most hard working
Trang 8the rotator and most of all, dishwashing My past and present officemates, Sophie, Victor,
George, Deyi and Mike, were great pals to share the office with The coffee breaks with my cheerful officemates were the energizer of my daily routine I also thank all my friends in the department and the church I attend for their support and prayers They made it possible for me
not only to focus on my study but also to have a great life
1 owe the biggest debt to my family in Korea My parents have been enormous support in every step of my journey Without their love and prayers, I would not be here To my brother and sister, Sung-min and Sung-sil, I love you guys To Sung-ihn, my sister who has been
watching over me from the heaven above, I will always cherish the memories we shared together
I miss you so much
Last but not the least, I thank Crystal, my companion, my wife and the biggest gift from
God She has always been there to encourage me throughout my long an difficult journey
Trang 9Acknowledgrmnefits HH HH HT TH TH Hà HH TH HT HH HH1 01111011 vi 'Tabl€ of Cofnt€fit HH TH TH HH nàn TH HH HH HH HH 011001110710010 011.0111190 vill List Of Tables .cccesssesssssssssssesssesesesssessssssesvessssssutsssesssesssessseesuceaneensecseceuesssenseeeueansecseeqnneenutesseesnesseessecees List of ÏÍÏustratiOfns HH HÀ Hà Hà HT TT TH ng HT HH1 041711 T1111.14110 0110 xi Chapter 1 1.1 IntrOducCtIOn th th HH TH HH TH TH TH HT 1n 1111111 011 T1111.1., 1 1.2 Research CJ€CtiV€S HH HH HH TH ng TH HH 01111011 111111011111 g11 2 1.3 Dissertation V€TVICW uc Hà HH TK HH111710111012117111 1117 110 3 R€Í€T€TIC€S HH HH HH ngà Hà HH HH HH HH TY g1 11117171011111711111171111100 77 5 Chapter Ð HH Ha TH TH TH TH TT TH H10011011107107107150T1011 H70 7 21 ÍntrOdtUCtIOR cc Ăn HẾ HH Hà Tàn HH HH KH TH TH 07110714071 21.7 7 2.2 Materials and ÍMethods cà HH no HH HH 111101110110111111 11 9
2.2.1 Chemicals and samplÌes HT ng 0111111111011 011 g0 9
2.2.2 PAHanalysis HH nh KH KH H1 H111 011011411411 1k 10
2.2.3 Physical and chemical characterization of samples essescsssecseessssecsseessseeessecssseessees 11
2.2.4 Desorption €XD€FITN€TIS HH HH H111 17 1111011121.11 00 1x6 12 2.2.5 _ Intraparticle microprobe two-step laser desorption, laser ionization mass
spectrometry (UL?7MS) measurements cscsecsessssssssessessesnssevenscessessecsessesssenssaseenseneeaeeeestesteenens 12 2.2.6 PAH uptake by semi-permeable membrane devices (SPMD) vcccrcee 13 2.3 Results and ÏĐisCussiOn ĩ2 TH ng 11H H11 11011011111101111241111 11 13 2.3.1 Soil characterization HH HT HH HH1 010011111114111411011 11 112 13 2.3.2 The availability of PAHs from the contaminated SOIÍ «ccckerkereriresrsrrke 26 24 Supporting ÍnfÍOfrALÏOHA Hàn HH HH TH 01108111 1101111111117111011 020 36 References csessecsesssesssssscessssessscsscssessvssecssensessesssscssecssqussnsscssesuecssensccusssussussssssscsusssussussescssessvensesasessseseenes 41 Chapter nạnD3DDD 1 44 3.1 Tmtroduction ccsssesssescssessesssessssssesssesssssssesseccsnsssussssecsssesasessseaneesusceuvecsensasecseensecesseesuesseesaneesees 44 3.2 Materials and IMethOdis sáng HH HH H011 110111071117111 1.00 46
3.2.1 Chemicals and sOrbenis + HH HH 011g 01 11x re 46
3.2.2 Sorption isothcrms and kinetiC €XDCFỈT€TIS c1 ky 47 3.2.3 Measurement ofintraparticle diffusion of PA Hs ĂSHenHeieerieeerie 48
3.3 Results and ÏisCussiOf HH HH TH HH 10 1 0T111111011100710011111 116 51 3.3.1 Sorbent prOperti€s HH TH HH HH Hà HH gà 51
Trang 103.3.5 Modeling results HH HH HH HH HH ngày 67 3.4 Supporting ÍÏnfOrmatÍON chàng TH HH HH HH 0111111110111114114124 1300 73 3.4.1 Supplementary figures and discussiofa ch 140111011x 1x crrke 73 3.4.2 Numerical modeÌs 5< 4 HH 10011111 80 Reference .cccsssssesssecssesssessseessesssseessesssecanesausssscesesssesesssssssssssssssssesseausensssavecsesenseesssessccsequeeqsecsunecsussscesseesees 83 Chapter 87 4.1 ÏntrOduCtiOR uc.“ TT ng HH TY TH TH TH 11111111101101107171171101 11 87
4.2 Materlals and MethOdis HH HH HH1 11111011 89
4.2.1 Modeling PAHI mass trafisÍC HH HH H011 011011111 te 89 4.3 Results and ÏDiSCUSSiOf HH TH HH TH ng HH1 11k 93 4.3.1 Model simulation sọ nọ HH TH HH H11 1110171011011cgyeg 93
4.3.2 Application of the model: Contamination sC€fiariOS c«ceetnsietrieriererke 99
4.4 Supporting Information cccssssssesssssessssssssesssesseesscssesseeseessesssenseessssnsansaneesseenessenseeseens 108
Trang 11Table 2-1 Table 2-2 Table 2-3 Table 2-4 Table 52-1 Table 3-1 Table 3-2 Table 3-3 Table 4-1 Table 4-2 Table 4-3 Table S4-1
Comparison: of total polycyclic aromatic hydrocarbons (PAH)-concentrations of various sieve and density fractions of soil from an unplanted and a planted phytoremediation test plot ssssssssssssssessesssecssasssseseessssssesssssseesecteerseenneccseeseenseeseeesess 18
Petrographic analyses of various soil fractions cscsssssssesssessseesesseeeseecutecsessecnseeses 20
Particle type analysis for the 1 to 2.3 mm sieve fraction of the native soil SAfTPÌ€ HH HH TH TH HH TH HT TH HH HH TH T.1212111121101 170 25 Comparison with literature values of estimated apparent diffusivities in the light-density fraction of native soil from the coke Oven SỈt€ veseeicrirrvee 30
Mass distribution and PAH distribution for the native soil sample separated
into various density and sieve ÍTACtÍOFAS chen HH 0101111 xe 36 SOrbenit DFOP€FLÍCS cọ HH HH TH HH HH 0011011001141 171.0 52 lsotherm parameters for POM, coke, and activated carbon -.cceesoeceecekserssee 56 Kinetic modelling r€suÏts son HH TH HH ng HH1 g1 gáy 59 Input parameters for Ford soil - POM model simulatioa -ccccccerirssteeree 94 Properties of Transmission oil and Tar decanter sÌudge ccccsrree 101 Properties of the modeÌ sedirmerit «kh 1k6 101
Trang 12Figure 2-1 Distribution of polycyclic aromatic hydrocarbons (PAH) compounds in native
soil (< 1 mm) collected adjacent to the precipitator tank alongside the coke battery at the Rouge coke oven site (2earborn, MI, SA) c eeerree 15
Figure 2-2 Polycyclic aromatic hydrocarbons (PAH) concentration of amended soil
samples from phytoremediation test plots planted for 1 and 3 years with Eupatorium perfoliatum and from the respective unplanted control plot,
comparing the bulk soil (<2.3 mm), Figure 2-2a and the fines (<<0.063 mm), Figure 2-2b The error bars represent the standard deviation from analysis of five to nine 1ndividual sarpÌ€§ son HT TH HH HH HH ngư 16
Figure 2-3 Microscopic images of particles from the native soil showing (a) a cut and polished aggregate with a density < 1.8 g/cm3, H=high volatile coal, T=tar
sludge, 600% in oil with reflected light, (b) a cut and polished aggregate with a density > 1.8 g/cm3, B=ball of coal fines, W=white coarse mineral, 600% in oil
with reflected light, (c) various conglomerates with a density < 1.8 g/cm3 from
the 1 to 2.3 mm sieve fraction, total polycyclic aromatic hydrocarbon (PAH)- concentration of each conglomerate given in [mg/kg] as numbers, (d) minerals
and conglomerates with a density > 1.8 g/cm3 and organic coatings from the
1-2.3 mm sieve fraction, (Figure 2-3 e to h shown in the next page) 21 Figure 2-3 Microscopic images of particles from the native soil showing (e) miscellaneous
particles with a density < 1.8 g/cm3 from the 1-2.3 mm sieve fraction, total PAH-concentration of each conglomerate given in [mg/kg] as numbers, (f) minerals and conglomerates with a density > 1.8 g/cm3 with less visible ofganic coatings from the 1 to 2.3 mm sieve fraction, (g) embedded and cut particle with a density < 1.8 g/cm3, and (h) split mineral with a density > 1.8 g/cm3 showing tar sludge or pitch coating c«cccchnHHH 101kg 22 Figure 2-4 Fraction of PAH compound mass desorbed from the low-density fraction
(Figure 2-4a) and the high-density fraction (Figure 2-4b) of native soil The
lines show the fitted Equation 2-Í « ch g4 111011 ke 27
Figure 2-5 Average uL?MS signal intensities for the molecular mass 154 (acenaphthene),
Trang 13Figure 2-6 Figure $2-1 Figure $2-2 Figure $2-3 Figure S2-4, Figure 3-1, Figure 3-2 Figure 3-3,
Uptake of polycyclic aromatic hydrocarbons (PAHs) into semipermeable membrane devices (SPMDs) after two weeks of continuous rotation with sediment or soil The data are expressed as percentage of the total PAH-mass
in the batches taken up by the SPIM4 HH HH ng re Sieve and density fractions of soil from the unplanted plot, sampled after three
YEALS ores es sessssssessucssecnscssenssssecenscucsscsessessscsuscsusasecssssseenesavesseesessecsssescsucesseatesssesiestassesnensees Sieve and density fractions of soil from the plot planted with Expatorium Derfoliatum, sampled after thr€€ €AFS chu gi
Visually distinguished particle types from the 1-2.3 mm sieve fraction
Fraction of the total PAHs desorbed from the bulk soil and two density ziaie T1 an Sorption isotherms for phenanthrene (triangles) and pyrene (diamonds) on (a) polyoxymethylene, (b) coke, and (c) activated carbon The fitting parameters for the Freundlich isotherms are provided in Table 3-2 For activated carbon
the Freundlich isotherm was fitted also for the lower concentration range only
(broken Line) seseessesesssessessesssssssssssssssscssssssessossvessscseaseesssssseasasseeaeneesasenseaeeneeneeasesseeseessees Kinetic sorption experiments for phenanthrene (triangles) and pyrene (diamonds) for polyoxymethylene (a,b), coke (c,d), and activated carbon (e,f) Filled symbols represent data for the finer particle size The particle diameters were 1-1.4 mm and 2-2.8 mm for polyoxymethylene, 0.11-0.25 mm and 0.06- 0.11 mm for coke, and 1-2 mm and 0.06-0.25 mm for activated carbon Lines through the data points represent the model fit, where PoD denotes polymer
diffusion, PD denotes pore diffusion, and BPK denotes the branched pore
kinetic model Also shown in the Figures are the equilibrium Kd,eq values for 37 38 39 40 54
the batch systems calculated from the sorption isothefrms c.vreeroce 61 Images and pL?MS-measurements for polyoxymethylene(a,b), coke(c,d), and
activated carbon (e,f) exposed to an initially nearly saturated phenanthrene solution in a closed batch system The filled triangles show a concentration profile measured with uL2MS on an embedded and sectioned particle shown in the adjacent image Consecutive shots are approximately 40 um apart and taken along a line from the particle edge across the particle center to the
opposite edge Empty triangles show average values for shots equidistant from the outer surface of the particle Averages were calculated from three cross- sections measured on different particles Because of the current limitation of
Trang 14Figure 3-4 Figure $3-1 Figure $3-2 Figure $3-3 Figure $3-4 Figure $3-5 Figure $3-6,
UuL2MS-measurements for polyoxymethylene (a,c,e,g) and activated carbon (b,d,f,h), showing the phenanthrene (triangles) and pyrene (diamonds) molecular mass signals inside sectioned particles as a function of the distance from the outer surface and time Shown are average values for shots equidistant from the outer surface of the particle, calculated from three profiles
measured across the center of the same particle Each particle was enclosed in a batch with 40 mL of water initially nearly saturated with phenanthrene and pyrene Signal intensity is normalized by the average intensity measured as a 50-shot average on the exterior surface of the same particle pL2MS-
measurements are compared with the concentration profiles predicted from
the diffusion models shown as solid or broken lines Note that these lines have not been fitted to the pL*MS-data The first shot of the laser beam is often partially on the particle surface and partially outside the particle surface resulting in low signal intensity ccccssssessessessesssessesseessecsensesscesessnsanscseesissneseeeaenneeee SEM images of razor-cut particle of (a) coke and (b) activated carbon with an inserted enlargement of a 40x40 ym spot with a crack/fracture The size of the enlargement in the original image is indicated by the filled white square The 40x40 ym spot includes both macro- and micro-porous regiofis
Particle-size dependent Na-absorption isotherms for COke -ccecccsccceecee
SEM-pictures of activated carbon showing (a) a relative compact region and (b)
a fragmented r14tfÏX c cst TH HH HH THẾ Hàn THẾ HH HH HH Hi HH ng nà
Fitted Langmuir isotherms for coke (a,c) and activated carbon (b,d) with phenanthrene (triangles) and pyrene (diamonds) as solutes Two forms of
lineatization for the Langmuir isotherm were used to fit the data as described
by Walters and Luthy (38), one provides a better fit for high C (broken line), the other for low Ce (Solid line) ccsssssscessssssscssecseessesseanecseceuseseessessecuecseessessessesseeess
Comparison of measured Freundlich isotherms with literature data for phenanthrene (a) and pyrene (b) sscsssessssssessesssessessnesssessneessessneenesaneeseeeseeeseeeaerssens
yL2MS-measurements for polyoxymethylene (a,c) and activated carbon (b,d), showing the phenanthrene (triangles) and pyrene (diamonds) molecular mass signals inside sectioned particles as a function of the distance from the exterior
surface Shown are average values for shots equidistant from the exterior
surface of the particle, calculated from three profiles measured across the center of the same particle Signal intensity is normalized by the average intensity measured as a 50-shot average on the exterior surface of the particle
Each particle was exposed initially to nearly saturated aqueous solutions of
66
- 12
Trang 15Figure 4-1 Figure 4-2
Figure 4-3
Figure 4-4
set-up with a continuous supply of phenanthrene and pyrene molecules to the aqueous phase via an a1r-bridE€ «tt nà HH 0101 01H tk Schematic dormains of the rnass trarnsf€r fOdeÌ - ch ch Hy re,
Comparison of experimental results with the modeling results (a) Soil-to-
POM ratio = 2 g/g (POM dose = 0.5 g/g), phenantherene, (b) Soil-to-POM
ratio = 0.2 g/g (POM dose = 5 g/g), phenantherene, (c) Soil-to-POM ratio = 2 g/g (POM dose = 0.5 g/g), pyrene, (d) Soil-to-POM ratio = 0.2 g/g (POM
dose = 5 Ø//Ø), DYF€R nh HH HH Hà HH HH Hà nhiệt
Phenathrene uptake in sorbent added to Ford soil showing the transitions of mass transfer controlling domains (a) POM, and (b) AC enstsssentssenesenes Simulation of aqueous phase concentration changes over five years (a) Transmission oil with activated carbon, coke breeze, POM, and without the sorbent, (b) Tar decanter sludge with activated carbon, coke breeze, POM, and ¿0108318 14 108 1 Figure 4-5 Phenanthrene mass fraction in each cormnpartment and the biodegraded fraction Figure S4-1 Comparison of aqueous phase concentration of PAHs to Groundwater Risk
Trang 16Introduction
11 Introduction
Polycyclic aromatic hydrocarbons (PAHs) comprise two or more fused benzene rings arranged linearly, angularly, or in clusters These compounds are among those contaminants teferred to as persistent organic pollutants They are a major environmental concern because they
are ubiquitous and because metabolites of several PAHs are mutagenic and carcinogenic (7-3)
Trang 17Due to their large hydrophobicity and low solubility, typically PAHs are found associated with organic matter in soil and sediments Moreover, black carbonaceous materials such as soot and charcoal are now considered the biggest depository of PAHs owing to these materials
showing exceptionally strong sorption of PAHs (5-7) Various types of black carbonaceous
materials are found in the environment and they show different sorption behaviors due to somewhat different physical and chemical properties (8) This fact makes the assessment of the impact of PAH contamination in soil and sediment difficult For these reasons the systematic characterization of contaminated site soils and sediments becomes crucial for accurate evaluation of environmental risk
Given the fact that the sorption of hydrophobic organic contaminants (HOCs) to black carbonaceous matter is extremely strong, the idea of adding activated carbon as particulate sorbent to contaminated sediment has been discussed as an in-situ sediment treatment method
Zimmerman et al reported successful results from laboratory scale tests in assessing this concept
(9, 10) Also, a recent study on the absorption efficiency of HOCs by clams from different carbonaceous particle types as diet provided a strong basis for the activated carbon addition as a novel in-situ remediation technique for contaminated sediments (77) However, there is a clear need for mechanistic understandings of the kinetics and mass transfer phenomena in a system comprising contaminated soil or sediment, surrounding water, and the added sorbents to advance the in-situ stabilization technique
1.2 Research Objectives
The two key objectives of this study are to understand the relationship between PAH association with contaminated site soil and its availability, and to provide more fundamental
understandings of mass transfer phenomena of PAHs between the soil or sediment and its
Trang 18and chemical properties of the soil matrix, particle-scale level analysis of PAH association with the soil, and several tests to assess PAH availability Secondly, kinetic studies and model
simulations will advance fundamental and mechanistic understandings of PAH mass transfer
during the application of the in-situ stabilization technique These objectives were accomplished through the following three separate studies
1.3
The primary objective of the first study was to characterize PAH association with the contaminated soil from a Ford Motor Company manufacturing site Comprehensive investigation of the soil identified the historical source of the contamination, the nature of the localization and binding of PAHs within the soil matrix, and the mobility and availability of the compounds Further, these findings were used to interpret the results and feasibility of three-year phytoremediation treatment pilot test performed at the site by a third party
The objective of the second study was to understand fundamentals of PAH sorption and
diffusion behavior into different organic sorbent materials This includes, in addition to the traditional sorption experiments, the employment of micro laser-desorption/laser-
ionization mass spectroscopy (uL2MS) to attempt direct observation of the long term
diffusion inside the sorbent particles The results from the direct observation using uL2MS were used to evaluate various diffusion-based kinetic models
The main objective of the third study was to evaluate a numerical model that simulates the mass transfer of PAHs during the application of the in-situ stabilization technique
using sorbent amendment The modeling results were compared to laboratory scale
experiments and the potential of broad applicability of the model to different situations was assessed
Dissertation Overview
Trang 19and 4, and they are in the form of three papers that have been published or will be submitted for publication in peer-reviewed journals
Chapter 2, ‘Physicochemical characterization of coke plant soil for the assessment of
polycyclic aromatic hydrocarbons availability and the feasibility of phytoremediation’, describes particle-scale characterization of contaminated site soil for the identification the historical source
of PAHs and the role of black carbonaceous materials in the association of the compounds with the soil matrix, especially tar decanter sludge A diffusion model was employed to interpret the release of PAHs from the site soil and various tests revealed the limited availability of the
compounds to the surrounding environments This work has been published by Sungwoo Ahn, David Werner, and Richard G Luthy in Environmental Toxicology and Chemistry (12)
Chapter 3, “Phenanthrene and pyrene sorption and intraparticle diffusion in
polyoxymethylene, coke, and activated carbon’, describes the direct observation of the diffusion of the selected PAHs into organic model sorbents using a state-of-the-art instrument, »L2MS Various diffusion-based models combined with the sorption isotherm and kinetic studies were evaluated by the comparison of the direct observation and the model predictions This work has been published by Sungwoo Ahn, David Werner, Hrissi K Karapanagioti, Donald R McGlothlin, Richard N Zare and Richard G Luthy in Exvironmental Science and Technology (13)
Chapter 4, ‘Modeling PAH mass transfer in a system of contaminated soil or sediment
amended with organic sorbents’, deals with the numerical model simulation of the mass transfer
of selected PAHs in the mixed system of the contaminated solid, water, and added sorbent The modeling work combines the findings from the previous two studies and provides more fundamental and mechanistic understanding of in-situ sequestration of the pollutants by adding
organic sorbent This part of the work is being prepared by Sungwoo Ahn, David Werner, and
Richard G Luthy for publication in a prominent peer-reviewed journal
Trang 20References
10
Douben, P E T., PAHs: an ecotoxicological perspective Wiley: Chichester, England; Hoboken,
NJ, USA, 2003; p x, 392
Harvey, R G., Polycyclic aromatic hydrocarbons: chemistry and carcinogenicity Cambridge University Press: Cambridge; New York, 1991; p 396
Harvey, R G., Polycyclic aromatic hydrocarbons Wiley-VCH: New York, 1997; p xili, 667
United States Office of the Federal Register Code of federal regulations, Title 40: Protection of
Environment, Office of the Federal Register National Archives and Records Administration: Washington, D.C., USA, 2003; p v
Karickhoff, S W., Sorption Kinetics of Hydrophobic Pollutants on Natural Sediments Abstracts of Papers of the American Chemical Society 1979, (APR), 113-113
Gustafsson, O.; Gschwend, P M., Soot as a strong partition medium for polycyclic aromatic hydrocarbons in aquatic systems Modecular Markers in Environmental Geochemistry
1997, 671, 365-381
Bucheli, T D.; Gustafsson, O., Quantification of the soot-water distribution coefficient of PAHs provides mechanistic basis for enhanced sorption observations Environmental Science and Technology 2000, 34, (24), 5144-5151
Jonker, M T O.; Koelmans, A A., Sorption of polycyclic aromatic hydrocarbons and polychlorinated biphenyls to soot and soot-like materials in the aqueous environment: mechanistic considerations Environmental Science and Technology 2002, 36, (17), 3725-3734 Zimmerman, J R.; Ghosh, U.; Millward, R N.; Bridges, T S.; Luthy, R G., Addition of catbon sorbents to reduce PCB and PAH bioavailability in marine
sediments:Physicochemical tests Environmental Science and Technology 2004, 38, (20), 5458- 5464
Zimmerman, J R.; Werner, D.; Ghosh, U.; Millward, R N.; Bridges, T S.; Luthy, R G., Effects of dose and particle size on activated carbon treatment to sequester
polychlorinated biphenyls and polycyclic aromatic hydrocarbons in marine sediments
Trang 2111 McLeod, P B.; Van Den Heuvel-Greve, M J.; Allen-King, R M.; Luoma, S N.; Luthy, R G., Effects of particulate carbonaceous matter on the bioavailability of benzo[a]pyrene and 2,2 ',5,5 '-tetrachlorobiphenyl to the clam, Macoma balthica Environmental Science and Technology 2004, 38, (17), 4549-4556
12 Ahn, S.; Werner, D.; Luthy, R G., Physicochemical characterization of coke-plant soil for the assessment of polycyclic aromatic hydrocarbon availability and the feasibility of phytoremediation Environmental Toxicology and Chemistry 2005, 24, (9), 2185-2195
13 Ahn, S.; Werner, D.; Karapanagioti, H K.; McGlothlin, D R.; Zare, R N.; Luthy, R G.,
Phenanthrene and pyrene sorption and intraparticle diffusion in polyoxymethylene, coke,
Trang 22Physicochemical Characterization of
Coke Plant Soil for the Assessment of
Polycyclic Aromatic Hydrocarbons
Availability and the F easibility of
Phytoremediation
2.1 Introduction
Polycyclic aromatic hydrocarbons (PAHs) are formed in the coking process from the heating of coal in the absence of oxygen (1) The PAH emissions from coke ovens are partially
gaseous with another portion of the PAHs associated with fly ash particles and soots and with
Trang 23plant is often highly contaminated with PAHs, and the cleanup of such sites is a major challenge for brownfield remediation
Beginning in the 1920s, the Ford Motor Company owned and operated coke ovens and a
by-products plant at its Rouge manufacturing complex in Dearborn, Michigan, USA, where it
produced coke for its metallurgic furnaces Deposits on the soil near the coke ovens from decades of coke production include coal/coke residuals, dust, sand, and industrial debris contaminated with PAHs The Rouge Renovation project aims to transform the Rouge
manufacturing complex from an icon in vertically integrated automotive manufacturing into a
model of a 21st century sustainable manufacturing center (3, 4) In this regard, phytoremediation is currently being investigated as an in-situ management strategy for the reduction of PAH- contaminant concentrations in soil from the Rouge coke oven site (5) Phytoremediation uses native plants and natural processes to reduce PAH-levels in contaminated soils while restoring habitat quality and helping to achieve the overall restoration goals Besides the potential degradation and transformation of the PAHs, expected benefits from phytoremediation at the
Rouge coke oven site are the filtration of storm water runoff, the creation of a wildlife habitat,
and the beautification of the landscape (5)
In this context, researchers at Michigan State University evaluated the ability of 18 native Michigan plant species to reduce PAHs in amended soil from the coke oven facility at a phytoremediation field demonstration site at Allen Park, Michigan, USA (5) Certain plants have the potential to metabolize PAHs, and plants may also assist PAH degradation indirectly by simulating microbial growth and biodiversity (6) The bioavailability of PAHs in contaminated soil is likely to be a critical factor for the success of phytoremediation because bioavailability can limit the rate and extent of PAH-biodegradation by plants and microorganisms (/-10) Black
carbonaceous particles and soots, which are ubiquitous at the Rouge coke oven site, may be
Trang 24the degradability of PAHs via phytoremediation depends critically upon the type and amount of
carbonaceous sorbent materials within the soil matrix
This study assesses PAH-contaminant availability in the native coke oven site soil and uses these findings to interpret results from thtee years of phytoremediation of amended coke
oven site soil with the species Expatorium perfoliafum, commonly known as Boneset Expatorium
perfoliatum was among the native Michigan plant species that showed a promising early trend in
reducing PAHs in greenhouse studies, and it could survive over the winter season (5) We report the distribution and sorbent-type association of PAHs in native soil from the coke oven site and
in amended soils from the phytoremediation field demonstration site This work explains
potential physicochemical constraints to phytoremediation of PAHs in ground surface materials
from the coke plant site, where the majority of the PAHs is associated with coke by-products plant waste like tar decanter sludge
2.2 Materials and Methods
2.2.1 Chemicals and samples
Chemicals Hexane, acetone, pentane, cyclohexane, and methylene chloride were purchased as pesticide grade solvents from Fisher Scientific (Pittsburgh, PA, USA) Solvents
were checked regularly for PAH contamination Anhydrous sodium sulfate (Fisher Scientific) was
ptepared by drying in an oven at 105 °C for 24 h Silica gel (Fisher Scientific) was activated at 130 °C for 16 h The PAH standard solutions for calibration were from Ultra Scientific (North Kingstown, RI, USA)
Soilsamples A composite native soil sample was collected from a contamination hotspot adjacent to the precipitator tank alongside the coke oven battery at the Ford Rouge Manufacturing Complex (Dearborn, MI, USA) in September 2001 by Michigan State University Four composite, amended soil samples from the Ford- Michigan State University
Trang 25plots were collected in November 2001 after one full-growth season One composite sample was
from an unplanted control plot and one from a plot planted with the species Eupatorinm perfolatum Both soil samples were amended with 10% by volume yard compost and 5% by volume chicken
manure at the beginning of the phytoremediation evaluation in September 2000 In 2003, two
additional samples were obtained after three full-growth seasons from the unplanted plot and the test plot planted with the species Expatorium perfoliatum Soil samples were stored in closed
containers at 4 °C until use
Wet sieving and density separation Wet sieving separated samples into four size fractions (1-2.3 mm, 1-0.25 mm, 0.250-0.063 mm, and < 0.063 mm) Density separation with a saturated cesium chloride solution with a density of 1.8 g/cm} was used to separate particulate coal, coke, by-product waste, and wood-derived materials from the mineral fraction of the soil In some experiments, the lighter density fraction was separated further using a cesium chloride solution with a specific gravity of 1.5 to remove wood and plant material with some entangled particulate carbon material from the coal and coke and coke by-products plant waste fraction of carbonaceous particulates
2.2.2 PAH analysis
The PAH concentrations of soil samples were measured by following U.S
Environmental Protection Agency (U.S EPA) _ standard method 3550B
(http://www.epa.gov/epaoswer/hazwaste/test/3_series.htm) Air-dried samples (no more than
Trang 26At least triplicate samples were extracted A 3.1 ppm standard of the 16 U.S EPA priority
pollutant PAHs was run with every series of samples to validate the calibration
Particle PAH analysis Individual coarse particles from the light density fraction were weighed, crushed, immersed in hexane/acetone, and passively extracted in 2 ml vials
with a Teflon®-lined cap for three weeks The hexane/acetone was replaced daily during the first
week and once again after the second week The combined extracts were cleaned and analyzed as described above
2.2.3 Physical and chemical characterization of samples
Total organic carbon content was determined for selected samples by Huffman Lab (Golden, CO, USA) The Brunauer, Emmett, and Teller surface area (BET-SA) and pore size distributions were measured at 77 K using a Coulter SA 3100 surface area and pore size analyzer (Coulter, Miami, FL, USA) Petrographic analyses were performed for the identification of the coal, coke, and coke by-products plant waste by R&D Carbon Petrography (Monroeville, PA,
USA)
Particle-type analysis Particles from the 1 to 2.3 mm sieve fraction of the native soil sample were separated by density and then sorted under the microscope into various
classes based on appearance The following classes were distinguished in the low-density fraction
(<1.8 g/cm’): Solid tar and tar conglomerates by the presence of mineral grains in the matrix of asphalt-like clumps; coke-like particles by the irregular, macroporous, sponge-like shape; coal-like
particles by a black, shiny appearance without discernible macropores; plant material, which was
Trang 272.2.4 Desorption experiments
The PAH desorption studies were conducted at room temperature for 210 days Samples of the native soil and density-separated fractions of the 0.25 to 1 mm sieve fraction of the native
soil sample were used Desorption test followed the procedure used by Ghosh et al (13) One g of each the native soil and the heavy-density fraction sample was placed in a 40 ml size vial and 0.5 g of Tenax resin beads was added respectively One-half g of soil sample and 1 g of Tenax
beads were used for the light-density fraction soil sample due to its high PAH concentration The vials were filled with 1% sodium azide solution with minimal headspace and capped with a
Teflon-lined cap The vials were continuously rotated on a rotator Tenax resin beads were replaced with fresh resin beads at certain time intervals Harvested Tenax beads were extracted for PAH concentration measurement All samples were prepared in triplicate
2.2.5 Intraparticle microprobe two-step laser desorption, laser ionization mass spectrometry (yL’MS) measurements
Micro-L2MS, as described in Gillette et al (14), was used to observe the relative abundance of PAHs on the outer surfaces and interior sections of selected particle types This instrument uses a pulsed infrared laser beam (A=10.6 pm) focused on a 40-4m diameter circular
spot to desorb molecules from a chemical matrix in a process consistent with thermal desorption
Trang 282.2.6 PAH uptake by semi-permeable membrane devices (SPMD) The SPMDs, a biomimetic device to simulate fatty tissue, were used to study the passive PAH uptake from coke plant soil The SPMDs were custom-made from polyethylene (EST, St
Joseph, MO, USA), 50 mm long, and filled with 0.05 g triolein Experiments were performed
with native soil from the coke oven site, with amended soil planted for three years with the
species Eupatorium perfoliatum, and with amended soil from the respective unplanted control plots
For comparison, SPMD uptake experiments were performed with PAH-contaminated sediments from Milwaukee Harbor (MI, USA) and Harbor Point (NY, USA) An amount equivalent to 8 g
of dry soil or sediment was added to 40-ml clear glass vials and filled with deionized water (17) Sodium azide (1 g/L) was added and the vials tumbled at 20 rpm continuously for 14 days After
contact, the SPMDs wete cleaned and dialyzed in hexane Aliquots of the dialysate were analyzed
for PAHs
2.3 Results and Discussion
2.3.1 Soil characterization
PAH-analysis of the bulk native soil and its density fractions A composite native soil sample from the coke by-products plant was collected adjacent to the precipitator tank alongside the coke battery and was found to contain on average 92022 mg PAHs/kg soil The
PAH-compound abundance pattern is shown in Figure 2-1 This native soil sample from the by-
products facility had an average total organic carbon content of 21% by weight, as determined by total organic carbon analysis, and contained in each sieve fraction 13 to 30% by weight particulate
carbonaceous material separable by density from the heavier mineral particles, as shown in Table
Trang 29supporting information in Table $2-1 The individual PAH distributions for the separated
fractions in the native soil exhibited the same pattern as shown in Figure 2-1 for the bulk sample
Assessment of three years of phytoremediation with Eupatorium perfoliatum Total PAH concentrations in composite samples collected during the first growing season in May,
July, and September, 2001 were reported as: 113+7, 10145, and 9445 mg/kg total PAHs in the unplanted plot, and 9748, 7944, and 8448 mg/kg in the plot planted with Expatorium perfoliatum (5) Four composite soil samples were obtained from the phytoremediation field demonstration
site following years one and three, and these were analyzed to assess the overall performance during three years of phytoremediation Figure 2-2a compares the PAH-concentration of the <2.36 mm sieve fraction of soil from the test plots planted for up to three years with Eupatorium
perfoliatum with the PAH-concentration of soil from the respective unplanted control plots Both planted and unplanted plots contained native soil from the coke by-products plant site that was
amended with chicken manure and compost to increase the biodiversity and fertility of the soil
Total PAH-concentrations were 75+12 and 105460 mg/kg in soil from unplanted control plots
after one and three years, respectively, as compared to 91419 and 88425 mg/kg after one and three years of phytoremediation with Expatorium perfoliatum, respectively Thus, there is little significant difference between the total PAH-concentration of soil from the planted plots and
from the unplanted control plots Figure 2-2b compares the finest sieve fraction of soil from the
planted and unplanted plots Total PAH-concentrations in the <0.063 mm sieve fraction were
121+4 and 110+40 mg/kg in soil from unplanted control plots after one and three years, respectively, as compared to 112+5 and 10030 mg/kg after one and three years of
phytoremediation with Expatorinm perfoliatum Thus, soil planted with Expatorium perfoltatum had a slightly lower average PAH-concentration in the <0,063 mm sieve fraction for both year one and year three, but the difference is within the range of the experimental uncertainty In general, soils
from the field study exhibit substantial variability in the total PAH-concentrations for 2.5 g
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Trang 3116 CHAPTER 2 PAH ASSOCIATION WITH THE CONTAMINATED SOIL
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Polycyclic aromatic hydrocarbons (PAH) concentration of amended soil samples
from phytoremediation test plots planted for 1 and 3 years with Eupatorium perfoliatum and
Figure 2-2
from the respective unplanted control plot, comparing the bulk soil (<2.3 mm), Figure 2-2a and the fines (<0.063 mm), Figure 2-2b The error bars represent the standard deviation from analysis
Trang 32The total PAH-concentration in soil from the phytoremediation demonstration field site is much lower than that in the native soil collected adjacent to the by-products plant tar ptecipitator tank For the phytoremediation study, 400 cubic yards of site material were heavy- equipment-excavated, including some minimally contaminated soil from the periphery of the coke oven area and blended during soil amendment This diluted hot-spot contaminated material with lesser-contaminated site material
Subsamples of the soil planted for three years with Expatorium perfolatum and the respective control were separated into various sieve and density fractions Photographic images of these fractions are provided in Figures $2-1 and $2-2 as supporting information The 1.5 to 1.8 g/cm} density fraction consisted almost entirely of carbon materials (.e., coal, coke, and tar decanter sludge) related to the coking process, whereas the <1.5 g/cm} density fraction consisted of catbon materials from the coking process entangled with plant tissues and wood from the
compost and with plant tissue The soil from the planted plot had fewer coarse particles and a
higher content of wood and plant tissue compated to the soil from the unplanted plot, as is evident from a comparison of Figures $2-1 and S2-2
Table 2-1 compares the relative soil mass and the measured total PAH-concentration for
each size and density fraction, as well as the calculated average PAH-concentrations for each sieve fraction, the two density fractions, and the bulk soil From this analysis it appears that the PAH-
concentration of the finer light material is lower in the planted-soil as compared to the unplanted
soil The differences in the <1.5 g/cm? density fractions can be partially explained by a higher content of wood and plant tissue in soil from the planted plot Wood and plant tissue had much lower PAH-concentrations as compared to carbon materials from the coking process This was demonstrated for the coarsest sieve fraction, in which the wood/plant material could be manually separated from coal, coke, and similar particulate materials The wood and plant material had only
10 to 20 mg/kg total PAHs compared to more than a 1000 mg/kg in carbonaceous materials
from the coking process
From the above observations, it is concluded that three years of phytoremediation with
Hupatorium perfoliatum resulted at best in a small reduction of the total PAH-contamination, mainly
Trang 33
Table 2-1 Comparison: of total polycyclic aromatic hydrocarbons (PAH)-concentrations of
various sieve and density fractions of soil from an unplanted and a planted phytoremediation test
plot
Trang 34and a variable céntent of wood and plant tissue do not allow for a more precise assessment The
following discussion suggests that most of the PAHs are associated with tar decanter sludge and
that the PAHs in this material are not bioavailable for treatment by phytoremediation
Petrography was employed to identify likely sources and potential strong sorbents of
PAHs in native soil from the coke oven site This methodology provides valuable insight into the sorbent properties of soils and sediments (18, 19) Petrographic analysis of the light fraction (<1.8 g/cm?) and the heavy fraction (>1.8 g/cm’) of the native soil sample identified almost every type
of carbon potentially associated with the coking process and its by-products processes, as summarized in the two left-hand columns of Table 2-2 Identified particles include coal, coke, pitch, and tar decanter sludge The native soil contained 22% material with a density less than 1.8 g/ cm} or approximately 30% by volume as calculated from the bulk densities of the heavy and light material in the 0.25 to 1 mm sieve fraction The light fraction comprised by volume about 39% each coal and coke and 11% by-product plant waste such as tar decanter sludge, pitch, and cenospheres Petrographic analysis identified the same types of carbon in both density fractions of the native soil, but a ten times higher total volume in the lighter fraction as compared to the heavier fraction Light imaging and petrography revealed the presence of aggregates of tar sludge material adhering to mineral grains or coal Figure 2-3a shows a microscopic image of an
aggregate from the light density fraction, which was identified as coal fragments bound by tar
decanter sludge Figure 2-3b shows the same type of aggregate in the pores and on the outer surface of a coarse mineral grain The mineral matter increased the overall density of the
combined aggregate sufficient for it to report to the heavier density fraction
Soil from the phytoremediation field trial plots had a lower content of carbon materials from the coking process, as shown in the petrography results in the two right-hand columns of
Table 2-2, but the composition was similar as in the native site soil sample The amount of
material related to the coking process is approximately 15% by volume in the bulk soil from the
planted and unplanted plots at the phytoremediation field demonstration site Soil from planted
Trang 35
Table 2-2 Petrographic analyses of various soil fractions
Soil Native? Native Control Planted
Particle size 0-1 mm 0-1 mm 0-2.3 mm 0-2.3 mm
Density <1.8 g/cm} >1.8 g/cm2 Bulk Bulk
Range of total PATs? 900-2800 80-210 60-240 60-130 [mg/kg] Volume % Volume % Volume % Volume % Coal 35.4 2.2 4.9 5.7 Oxidized Coal/Coke 4.2 0.8 0.8 1.8 Coal/Coke Inerts ND-‹ ND 0.5 0.6 Total Coal Related 39.6 3.0 6.2 8.1 Coke 33.6 4.0 5.2 4.7 Anthracite in Coke 1.0 ND ND ND Depositional Carbon 3.8 2.6 2.0 2.0 Total Coke Related 38.4 6.6 7.2 6.7 Pitch Coke 0.4 ND ND 0.2 Pitch/Tar Sludge 7.4 0.6 0.3 0.8 Cenospheres 3.5 0.8 0.8 1.2 Total By-Product Related 11.3 1.4 1.1 2.2 Wood/Plant ND ND 2.3 9.8 Metal/Iron related 1.9 8.2 0.9 0.5 Graphite 0.4 0.6 0.2 0.3 Gummy aggregates ND 9.8 0.6 0.6 Various Minerals 8.4 70.4 81.5 71.8 Re Coke Oven 10.7 89 85.5 83
Trang 36
(a) Aggregate of coal and tar sludge (b) Aggregate with mineral core (c) Tar or pitch-bound light aggregates (d) High density coated minerals Figure 2-3 Microscopic images of particles from the native soil showing (a) a cut and
polished aggregate with a density < 1.8 g/cm3, H=high volatile coal, T=tar sludge, 600X in oil
_ with reflected light, (b) a cut and polished aggregate with a density > 1.8 g/cm3, B=ball of coal
fines, W=white coarse mineral, 600X in oil with reflected light, (c) various conglomerates with a density < 1.8 g/cm3 from the 1 to 2.3 mm sieve fraction, total polycyclic aromatic hydrocarbon (PAH)-concentration of each conglomerate given in [mg/kg] as numbers, (d) minerals and
Trang 37
(e) Miscellaneous light particles (f) High density minerals
(g) Cut low density particle (h) Split mineral with tar sludge coating
Figure 2-3 Microscopic images of particles from the native soil showing (e) miscellaneous
particles with a density < 1.8 g/cm3 from the 1-2.3 mm sieve fraction, total PAH-concentration of each conglomerate given in [mg/kg] as numbers, (f) minerals and conglomerates with a density
> 1.8 g/cm3 with less visible organic coatings from the 1 to 2.3 mm sieve fraction, (g) embedded
and cut particle with a density < 1.8 g/cm3, and (h) split mineral with a density > 1.8 g/cm3
Trang 38of the petrographic analysis indicate that the soil from the planted and the unplanted plots contains a comparable amount of the same carbon materials
PAH-analysis for particle types and individual particles Petrography
identified a variety of carbon materials in the native soil from the coke by-products plant site, sometimes in close association with each other and bound by tar decanter sludge, and sometimes with minerals as shown in Figures 2-3a and b The coarsest sieve fraction (1-2.3 mm) of the
native soil sample was separated into classes of similar particle types to identify the likely PAH source in this soil and to better understand the PAH-particle association in this complex mixture
Conglomerates with an appearance similar to tar decanter sludge or lumps of asphalt are shown in
Figure 2-3c These conglomerates had the highest PAH concentration of various optically- distinguished particle types in the 1 to 2.3 mm sieve fraction of the native soil sample from the
coke oven site, i.e., 12,500 mg/kg on average as reported in Table 2-3 These conglomerates of tar
sludge-like material were hard, and would not soften or melt when heated to 300 °C The analysis
of individual coarse particles revealed a significant variability in PAH-concentration, as shown in Figure 2-3c Some dark, tar sludge or asphalt-like conglomerates contained as much as four percent by mass PAHs Figures 2-3d, e, and f show more of the optically distinguished particle type classes in the native soil, and photographic images of all particle types are provided as
supporting information in Figure $2-3 The results in Table 2-3 demonstrate that coal- and coke-
like particles from the site had lower PAH-concentrations than tar sludge or asphalt-like conglomerates, despite the high carbon content of coal or coke The PAH concentration is best correlated with the amount of hexane/acetone soluble matter, which would be indicative of tar sludge Combined, these results suggest that most of the PAHs are associated with the polymeric matrix of tar sludge or pitch, which glues coal and coke fragments and minerals into complex aggregates Small amounts of this adhesive tar or pitch are likely associated with all particle types to a variable degree, either as coating or as fillings in pores, as shown in Figure 2-3b For instance,
the dark coated mineral grains from the heavy fraction shown in Figure 2-3d had higher PAH concentration as compared to the ones with a lighter color shown in Figure 2-3f
The binder in these aggregates and coatings, tar decanter sludge, and other tarry- or
Trang 39PAH-contamination in ground surface material at the coke oven site According to Alvarez et al (2), the coking process produces 1000 to 1200 tons/year tar decanter sludge and 200 to 250 tons/year of
pitch-like benzol distillation residue from by-products plants for a coke production of about 2.5 milliontons/year Tar decanter sludge is a U.S EPA classified hazardous waste because of its high
PAH content (20) This sludge forms when heavier solids separate out from the floating tar layer in the tar decanter Tar and pitch contain several percent by weight of the sum of the 16-U.S EPA listed PAHs (21), and the occurrence of tar and pitch in the native soil sample could actually explain the measured PAH concentrations Pure coke breeze was obtained from Ispat Inland (East Chicago, IL, USA) and analyzed for comparison It had neither measurable PAH concentrations, nor did it contain a measurable amount of hexane/acetone extractable matter (data not shown)
These results have important implications for the assessment of phytoremediation as a
Trang 40
Table 2-3 Particle type analysis for the 1 to 2.3 mm sieve fraction of the native soil sample
Hexane/ di nes, PAH-mass
BET- acetone stembunon Total PAH® distribution
foc SA? extractable on whole concn on whole sample matter basi asis sample basis [g/g] _[m?/g] [e/g] [wt 7] [mg/kg] [%] Light materiale from the 1 to 2.3 mm fraction of the native soil, <1.8 g/cm} Conglomerates 0.45 1.9 0.085 2.3 1220045500 42 Miscellaneous 0.78 0.6 0.040 2.7 560042200 22 Coke-like 0.80 0.6 0.014 3.1 550+270 2 Coal-like 0.75 Type II 0.022 1.7 6604400 2 Plant material ND+ ND ND 0.1 2104140 < 0.001 Light fraction 4500+2000 Heavy materiale from the 1-2.3 mm fraction of the native soil, >1.8 g/cm? Coated, dark 0.024 3.4 0.004 43.4 3604150 23 Coated, light 0.009 2.2 < 0.002 43.0 140+90 9 Speckles ND Type III < 0.002 3.5 14413 < 0.001 Heavy fraction 240+120 For comparison, coke breeze, not from the site, 1.7 g/cm} Coke breeze 0.90 0.7 < 0.002 - <10 -
4 The BET-surface area can not be determined for type III isotherms > PAH is polycyclic