contentspreface part i soilchapter 1 the forms and availability of pahs in soil31.1 the forms of pahs in soil31.1.1 fractionation methods of pah residues in soil41.1.2 desorbing fraction of pahs in soil51.1.3 non-desorbing fraction of pahs in soil71.1.4 bound residues of pahs in soil101.2 the availability of pahs in soil121.2.1 available fractions of pahs in soils as a function of aging time131.2.2 microbial degradation of available fractions of pahs in soils151.2.3 transformation of available fraction of pahs to bound residue in soils171.2.4 butanol-extraction technique for predicting the availability of pahs in soil181.2.5 phytoavailability of bound-pah residues in soils18chapter 2 gradient distribution of pahs in rhizosphere soil242.1 gradient distribution of pahs in rhizosphere soil: a greenhouse experiment252.1.1 gradient distribution of phenanthrene and pyrene in rhizosphere262.1.2 gradient distribution of root exudates in rhizosphere272.1.3 the correlations of pah concentration gradient with the conc entration gradient of root exudates in rhizosphere302.2 in situ gradient distribution of pahs in rhizosphere soil: a field study332.2.1 in situ gradient distribution of pahs in rhizosphere soil342.2.2 rhizosphere effects on pah distribution in soil372.3 rhizospheric gradient distribution of bound-pah residues in soils402.3.1 gradient distribution of bound-pah residues in rhizosphere412.3.2 mechanism of rhizospheric gradient distribution of bound-pah residues in soils46chapter 3 partition of pahs among soil�� water and plant root483.1 sorption of pahs by soils with heavy metal co-contaminants493.1.1 sorption isotherms of phenanthrene by soils503.1.2 sorption of phenanthrene by heavy metal-contaminated soils523.1.3 mechanisms of the heavy metal enhanced-sorption of phenanthrene by soils533.2 dissolved organic matter ��dom�� influences the partition of pahs between soil and water573.2.1 effect of inherent dom on phenanthrene sorption by soils593.2.2 effect of exotic dom on phenanthrene sorption by soils633.3 partition of polycyclic aromatic hydrocarbons between plant root and water673.3.1 partition of phenanthrene between roots and water683.3.2 estimation of partition coefficient of phenanthrene between root and water using a composition model703.3.3 partition of phenanthrene between root cell walls and water71chapter 4 impact of root exudates on the sorption�� desorption and availability of pahs in soil734.1 impact of pahs on root exudate release in rhizosphere734.1.1 impact of pah contamination levels on root exudation in rhizosphere744.1.2 distribution of root exudates in different layers of rhizosphere soil774.2 impact of root exudates on pah sorption by soils774.2.1 root exudate component-influenced sorption of pah by soil784.2.2 mechanism discussions804.3 impact of root exudates on pah desorption from soils834.3.1 desorption of pahs from soils as a function of root exudate concentration844.3.2 pah desorption by root exudates in different soils864.3.3 effects of soil aging on pah desorption by root exudates from soil874.3.4 desorption of different pahs by root exudates in soil884.3.5 impact of root exudate components on pah desorption in soil894.3.6 dissolved organic matter in soils with the addition of root exudates904.4 impact of root exudates on pah availabilities in soils924.4.1 impact of root exudates on n-butanol-extractable pyrene in soil934.4.2 impact of root exudate components on the n-butanol-extractable pyrene in soil954.4.3 mechanisms by which root exudate and its components influence pah availa-bility in soil98chapter 5 low-molecular-weight organic acids ��lmwoas�� influence the transport and fate of pahs in soil1015.1 lmwoas-influence the pah sorption by different soil particle size fractions1025.1.1 fractionation protocol of different soil particle size fractions1035.1.2 pah sorption by different soil particle size fractions1065.1.3 effects of lmwoas on pah sorption by different soil particle size fractions1085.1.4 mechanisms of lmwoa-influenced pah sorption by different soil particle size fractions1095.2 lmwoas enhance the pah desorption from soil1145.2.1 lmwoa-enhanced desorption of pah from pah-spiked soil1155.2.2 lmwoa-enhanced desorption of pahs from soils collected from a pah- contaminated site1185.2.3 mechanisms of lmwoa-enhanced desorption of pahs from soils1245.3 impact of lmwoas on the availability of pahs in soil1275.3.1 impact of lmwoas on the butanol-extractable pahs in soils1285.3.2 mechanism discussions1325.4 elution of soil pahs using lmwoas1335.4.1 elution of pahs in soil columns by lmwoas1355.4.2 distributions of pahs in soil columns1365.4.3 butanol-extractable and nonextractable pahs in soil