Contents Preface PART I SOIL Chapter 1 The forms and availability of PAHs in soil3 1.1 The forms of PAHs in soil3 1.1.1 Fractionation methods of PAH residues in soil4 1.1.2 Desorbing fraction of PAHs in soil5 1.1.3 Non-desorbing fraction of PAHs in soil7 1.1.4 Bound residues of PAHs in soil10 1.2 The availability of PAHs in soil12 1.2.1 Available fractions of PAHs in soils as a function of aging time13 1.2.2 Microbial degradation of available fractions of PAHs in soils15 1.2.3 Transformation of available fraction of PAHs to bound residue in soils17 1.2.4 Butanol-extraction technique for predicting the availability of PAHs in soil18 1.2.5 Phytoavailability of bound-PAH residues in soils18 Chapter 2 Gradient distribution of PAHs in rhizosphere soil24 2.1 Gradient distribution of PAHs in rhizosphere soil: a greenhouse experiment25 2.1.1 Gradient distribution of phenanthrene and pyrene in rhizosphere26 2.1.2 Gradient distribution of root exudates in rhizosphere27 2.1.3 The correlations of PAH concentration gradient with the conc entration gradient of root exudates in rhizosphere30 2.2 In situ gradient distribution of PAHs in rhizosphere soil: a field study33 2.2.1 In situ gradient distribution of PAHs in rhizosphere soil34 2.2.2 Rhizosphere effects on PAH distribution in soil37 2.3 Rhizospheric gradient distribution of bound-PAH residues in soils40 2.3.1 Gradient distribution of bound-PAH residues in rhizosphere41 2.3.2 Mechanism of rhizospheric gradient distribution of bound-PAH residues in soils46 Chapter 3 Partition of PAHs among soil, water and plant root48 3.1 Sorption of PAHs by soils with heavy metal co-contaminants49 3.1.1 Sorption isotherms of phenanthrene by soils50 3.1.2 Sorption of phenanthrene by heavy metal-contaminated soils52 3.1.3 Mechanisms of the heavy metal enhanced-sorption of phenanthrene by soils53 3.2 Dissolved organic matter (DOM) influences the partition of PAHs between soil and water57 3.2.1 Effect of inherent DOM on phenanthrene sorption by soils59 3.2.2 Effect of exotic DOM on phenanthrene sorption by soils63 3.3 Partition of polycyclic aromatic hydrocarbons between plant root and water67 3.3.1 Partition of phenanthrene between roots and water68 3.3.2 Estimation of partition coefficient of phenanthrene between root and water using a composition model70 3.3.3 Partition of phenanthrene between root cell walls and water71 Chapter 4 Impact of root exudates on the sorption, desorption and availability of PAHs in soil73 4.1 Impact of PAHs on root exudate release in rhizosphere73 4.1.1 Impact of PAH contamination levels on root exudation in rhizosphere74 4.1.2 Distribution of root exudates in different layers of rhizosphere soil77 4.2 Impact of root exudates on PAH sorption by soils77 4.2.1 Root exudate component-influenced sorption of PAH by soil78 4.2.2 Mechanism discussions80 4.3 Impact of root exudates on PAH desorption from soils83 4.3.1 Desorption of PAHs from soils as a function of root exudate concentration84 4.3.2 PAH desorption by root exudates in different soils86 4.3.3 Effects of soil aging on PAH desorption by root exudates from soil87 4.3.4 Desorption of different PAHs by root exudates in soil88 4.3.5 Impact of root exudate components on PAH desorption in soil89 4.3.6 Dissolved organic matter in soils with the addition of root exudates90 4.4 Impact of root exudates on PAH availabilities in soils92 4.4.1 Impact of root exudates on n-butanol-extractable pyrene in soil93 4.4.2 Impact of root exudate components on the n-butanol-extractable pyrene in soil95 4.4.3 Mechanisms by which root exudate and its components influence PAH availa-bility in soil98 Chapter 5 Low-molecular-weight organic acids (LMWOAs) influence the transport and fate of PAHs in soil101 5.1 LMWOAs-influence the PAH sorption by different soil particle size fractions102 5.1.1 Fractionation protocol of different soil particle size fractions103 5.1.2 PAH sorption by different soil particle size fractions106 5.1.3 Effects of LMWOAs on PAH sorption by different soil particle size fractions108 5.1.4 Mechanisms of LMWOA-influenced PAH sorption by different soil particle size fractions109 5.2 LMWOAs enhance the PAH desorption from soil114 5.2.1 LMWOA-enhanced desorption of PAH from PAH-spiked soil115 5.2.2 LMWOA-enhanced desorption of PAHs from soils collected from a PAH- contaminated site118 5.2.3 Mechanisms of LMWOA-enhanced desorption of PAHs from soils124 5.3 Impact of LMWOAs on the availability of PAHs in soil127 5.3.1 Impact of LMWOAs on the butanol-extractable PAHs in soils128 5.3.2 Mechanism discussions132 5.4 Elution of soil PAHs using LMWOAs133 5.4.1 Elution of PAHs in soil columns by LMWOAs135 5.4.2 Distributions of PAHs in soil columns136 5.4.3 Butanol-extractable and nonextractable PAHs in soil columns137 5.4.4 Impact of soil type on PAH elution138 5.4.5 Mechanisms of LMWOA-enhanced elution of soil PAHs140 5.4.6 Relationship between the elution of PAHs and the dissolution of metal ions141 5.5 LMWOAs enhance the release of bound PAH residues in soil146 5.5.1 The release of bound PAH residues in soils as a function of incubation time147 5.5.2 LMWOA-enhanced release of bound PAH residues in soil149 PART II PLANT Chapter 6 Uptake, accumulation and translocation of PAHs in plants157 6.1 Uptake pathways of PAHs in plants158 6.1.1 Root uptake of PAHs160 6.1.2 Shoot accumulation of PAHs161 6.1.3 Uptake time and PAH concentration influence their uptake by plants164 6.2 Accumulation and translocation of PAHs in plants with different compositions166 6.2.1 Accumulation of PAHs in roots167 6.2.2 Accumulation of PAHs in shoots171 6.2.3 Translocation of PAHs in plant173 6.3 Comparison for plant uptake of PAHs from soil and water174 6.3.1 Plant uptake of PAHs from water175 6.3.2 Plant uptake of PAHs from soil177 6.3.3 Comparison for plant uptake of PAHs from soil and water178 Chapter 7 Subcellular distribution of PAHs in plants181 7.1 PAH distribution in subcellular root tissues181 7.1.1 Fractionation protocol of root subcellular tissues182 7.1.2 Uptake of PAHs by roots182 7.1.3 Subcellular movement and distribution of PAHs in root cells185 7.2 Subcellular distribution of PAHs in arbuscular mycorrhizal roots188 7.2.1 PAH concentrations in subcellular tissues of arbuscular mycorrhizal roots189 7.2.2 Subcellular concentration factors of PAH in arbuscular mycorrhizal roots191 7.2.3 Proportion of PAH in subcellular tissues of arbuscular mycorrhizal roots192 Chapter 8 Metabolism of PAHs in plants194 8.1 Metabolism of anthracene in tall fescue194 8.1.1 Metabolism of anthracene in tall fescue195 8.1.2 Distribution of anthracene and its metabolites in subcellular tissues198 8.1.3 Metabolism mechanism discussion204 8.2 Enzyme activity in tall fescue contaminated by PAHs205 8.2.1 Enzyme activity in tall fescue206 8.2.2 Enzyme activity in subcellular fractions of tall fescue207 8.3 Inhibitor reduces enzyme activity and enhances PAH accumulation in tall fescue211 8.3.1 In vitro degradation of PAHs in solution with enzymes213 8.3.2 Effects of inhibitor on enzyme activities in plants215 8.3.3 Effects of inhibitor on the enhanced accumulation of PAH in plants217 Chapter 9 Arbuscular mycorrhizal fungi influence PAH uptake by plants221 9.1 PAH uptake by arbuscular mycorrhizal plants221 9.1.1 Arbuscular mycorrhizal colonization of root exposed to PAHs in soil222 9.1.2 PAH uptake by arbuscular mycorrhizal plants223 9.2 Arbuscular mycorrhizal hyphae contribute to PAH uptake by plant226 9.2.1 Three-compartment systems227 9.2.2 Mycorrhizal root colonization and plant biomass228 9.2.3 Concentrations of PAHs in mycorrhizal roots229 9.2.4 Partition coefficients of PAHs by arbuscular mycorrhizal hyphae230 9.2.5 Translocation of PAHs by arbuscular mycorrhizal hyphae233 Chapter 10 Utilizing PAH-degrading endophytic bacteria to reduce the plantPAH contamination236 10.1 Distribution of endophytic bacteria in plants from PAH-contaminated soils237 10.1.1 PAH concentrations in plants from PAH-contaminated soils238 10.1.2 Endophytic bacterial community in PAH-contaminated plants241 10.1.3 Cultivable endophytic bacterial populations in PAH-contaminated plants245 10.1.4 Amounts of cultivable endophytic bacteria in PAH-contaminated plants246 10.2 Inoculating plants with the endophytic bacterium Pseudomonas sp. Ph6-gfpto reduce phenanthrene contamination249 10.2.1 Isolation, identification, and gfp-labeling of Pseudomonas sp. Ph6250 10.2.2 Biodegradation of phenanthrene by Ph6-gfp in culture solution252 10.2.3 Colonization and distribution of Ph6-gfp in plants253 10.2.4 Performances of Ph6-gfp mediate the uptake of phenanthrene by plants258 10.3 Utilizing endophytic bacterium Staphylococcus sp. BJ06 to reduce plant pyrene contamination262 10.3.1 Isolation and identification of Staphylococcus sp. BJ06262 10.3.2 Biodegradation of pyrene by BJ06 in culture solution263 10.3.3 Reducing plant pyrene contamination using strain BJ06266 References270 Plates
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