Effect of Co-existing Heavy Metals and Natural Organic Matter on Sorption/Desorption of Polycyclic Aromatic Hydrocarbons in Soil: A Review

Document Type : Original Research Paper

Authors

1 Department of Civil Engineering, University of British Columbia, 6250 Applied Science Lane, Vancouver, British Columbia, Canada V6T 1Z4

2 Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver British Columbia, Canada V6T 1Z3

Abstract

Polycyclic aromatic hydrocarbons (PAHs), abundant in mixed contaminant sites, often coexist with heavy metals. The fate and remediation of PAHs depend heavily on the sorption and desorption behavior of these contaminants. The sorption behavior can in turn be highly affected by certain soil components and properties, such as soil organic matter (SOM) and the presence of heavy metals. Through review of the literature focused on research from 2006 to 2018, this paper discusses interactions, challenges, influencing factors and potential synergies in sorption/desorption of mixed PAHs and heavy metal contamination of soil. The presence of either natural organic matter or heavy metals can enhance the sorption capability of fine soil, retarding the PAHs in the solid matrix. The co-existence of SOM and heavy metals has been reported to have synergistic effect on PAHs sorption. Enhanced and surfactant desorption of PAHs are also affected by the presence of both SOM and metals. Remediation techniques for PAHs removal from soil, such as soil washing, soil flushing and electrokinetics, can be affected by the presence of SOM and heavy metals. More detailed studies on the simultaneous effects of soil components and properties on the sorption/desorption of PAHs are needed to enhance the effectiveness of PAHs remediation technologies.

Keywords


Afkhami, F., Karbassi, A. R., Nasrabadi, T., and Vosoogh, A. (2013). Impact of oil excavation activities on soil metallic pollution, case study of an Iran southern oil field. Environ. Earth Sci. 70, 1219-1224.
Agency for Toxic Substances and Disease Registry (ATSDR). (1995). Public Health Statement Polycyclic Aromatic Hydrocarbons (PAHs), 6 pp.
Agency for Toxic Substances and Disease Registry (ATSDR). (2009). Case Studies in Environmental Medicine, Toxicity of Polycyclic Aromatic Hydrocarbons (PAHs), 68pp.
Ahangar, A.G. (2010). Sorption of PAHs in the soil environment with emphasis on the role of soil organic matter: A review. World Appl. Sci. J. 11, 759-765.
 Ahn, C., Kim, Y., Woo, S. and Park, J. (2008). Soil washing using various nonionic surfactants and their recovery by selective adsorption with activated carbon, J. Hazard. Mater. 154, 153–160.
Alcántara, M.T., Gómez, J., Pazos, M. and Sanromán, M.A. (2008). Combined treatment of PAHs contaminated soils using the sequence extraction with surfactant-electrochemical degradation. Chemosphere 70, 1438-1444.
Alcántara, M.T., Gómez, J., Pazos, M. and Sanromán, M.A. (2009). PAHs soil decontamination in two steps: desorption and electrochemical treatment, J. Hazard. Mater. 166, 462–468.
Awoyemi, A. (2011). Understanding the Adsorption of PAHs from Aqueous Phase onto Activated Carbon. MSc Thesis, University of Toronto, Canada.               
Baird, W. M., Hooven, L. A. and Mahadevan, B. (2005). Carcinogenic polycyclic aromatic hydrocarbon-DNA adducts and mechanism of action. Environ. Mol. Mutagen. 45, 106–114.
Balati, A., Shahbazi, A., Amini, M.M. and Hashemi, S.H. (2015). Adsorption of polycyclic aromatic hydrocarbons from wastewater by using silica-based organic-inorganic nanohybrid material. J. Water Reuse Desalin. 5, 50-63.
Barnier, C., Ouvrard, S., Robin, C. and Morel, J.L. (2014). Desorption kinetics of PAHs from aged industrial soils for availability assessment. Sci. Total Environ. 470, 639-645.
Bostrom, C.E., Gerde, P., Hanberg, A., Jernstrom, B., Johansson, C., Kyrklund, T., Rannug, A., Tornqvist, M., Victorin, K. and Westerholm, R. (2002). Cancer risk assessment, indicators, and guidelines for polycyclic aromatic hydrocarbons in the ambient air. Environ. Health Perspect. 110, 451–488.
Brindley, G. W., Bender, R. and Ray, S. (1963). Sorption of non-ionic aliphatic molecules from aqueous solutions on clay minerals clay-organic studies-VII. Geochim. Cosmochim. Acta. 27, 1129-1137.
Cao, M., Hu, Y., Sun, Q., Wang, L., Chen, J. and Lu, X. (2013). Enhanced desorption of PCB and trace metal elements (Pb and Cu) from contaminated soils by saponin and EDDS mixed solution, Environ. Pollut. 174, 93-99.
Canadian Council of Ministers of the Environment (CCME). (2010a). Canadian Soil Quality Guidelines for the Protection of Environmental and Human Health. Polycyclic Aromatic Hydrocarbons.
Canadian Council of Ministers of the Environment (CCME). (2010b). Canadian Soil Quality Guidelines; Carcinogenic and Other Polycyclic Aromatic Hydrocarbons (PAHs) (Environmental and Human Health Effects), PN1445.
Cheng, K. and Wong, J. (2006). Effect of synthetic surfactants on the solubilization and distribution of PAHs in water/soil-water systems.  Environ. Technol. 27, 835–844.
Cheng, M., Zeng, G.,  Huang, D.,  Yang, Y., Lai, C., Zhang, C and Liu, Y. (2017). Advantages and challenges of Tween 80 surfactant-enhanced technologies for the remediation of soils contaminated with hydrophobic organic compounds. Chem. Eng. J. 314, 98-113.
Choi, S.D., Shunthirasingham, C., Daly, G.L., Xiao, H., Lei, Y.D. and Wania, F. (2009). Levels of polycyclic aromatic hydrocarbons in Canadian mountain air and soil are controlled by proximity to roads. Environ. Pollut. 157, 3199-206.
Cornelissen, G. and Gustafsson, O. (2004). Sorption of phenanthrene to environmental black carbon in sediment with and without organic matter and native sorbates. Environ. Sci. Technol. 38, 148-155.
Delle Site, A. (2001). Factors affecting sorption of organic compounds in natural sorbent/water systems and sorption coefficients for selected pollutants. A review. J. Phys. Chem. Ref. Data  30, 187-439.
De Jonge, L.W., Moldrup, P., De Jonge, H. and Celis, R. (2008). Sorption and leaching of short-term-aged PAHs in eight European soils: Link to physicochemical properties and leaching of dissolved organic carbon. Soil Sci. 173, 13-24.
Dunnivant, F. M.  and Anders, E. (2005).  A Basic Introduction to Pollutant Fate and Transport: An Integrated Approach with Chemistry, Modeling, Risk Assessment, and Environmental Legislation, John Wiley & Sons.
Eghbal, N., Nasrabadi, T., Karbassi, A. R., and Taghavi, L. (2019). Evaluating the Potential of Plants (leaves) in Removal of Toxic Metals from Urban Soils (Case Study of a District in Tehran City). Pollut. 5(2), 387-394.
El-Nahhal, Y.Z. and Safi, J.M. (2004). Adsorption of phenanthrene on organoclays from distilled and saline water. J. Colloid Interface Sci.  15, 269, 265-73.
Ewa, B. and Danuta, M-S. (2017). Polycyclic aromatic hydrocarbons and PAH-related DNA adducts. J. Appl. Genet. 58, 321-330.
Fazeli, G., Karbassi, A., Khoramnejadian, S., and Nasrabadi, T. (2019). Evaluation of Urban Soil Pollution: A Combined Approach of Toxic Metals and Polycyclic Aromatic Hydrocarbons (PAHs). Int. J. Env. Res. 1-11.
Federal Contaminated Sites Inventory (FCSI). (2018). http://www.tbs-sct.gc.ca/fcsi-rscf/home-accueil-eng.aspx, Accessed Feb. 10, 2018.
Fonseca, B., Pazos, M., Figueiredo, H., Tavares, T. and Sanroman, M.A. (2011). Desorption kinetics of phenanthrene and lead from historically contaminated soil. Chem. Eng. J. 167, 84–90.
Gao, Y.Z., He, J.Z., Ling, W.T., Hu, H.Q. and Liu, F. (2003). Effects of organic acids on copper and cadmium desorption from contaminated soils. Environ. Int. 29, 613–618.
Gao, J.A. and Pedersen, J.A. (2005). Adsorption of sulfonamide antimicrobial agents to clay minerals. Environ. Sci. Technol. 39, 9509-9516.
Gao, Y., Xiong, W., Ling, W. and Xu, J. (2006). Sorption of phenanthrene by soils contaminated with heavy metals. Chemosphere, 65, 1355–1361.
Gauthier, T. D., Seitz, W. R. and Grant, C.L. (1987). Effects of structural and compositional variations of dissolved humic materials on pyrene KQC values.  Environ. Sci. Technol. 21, 243-48.
Greish, S., Rinnan, A., Marcussen, H., Holm, P.E. and Christensen, J.H. (2018). Interaction mechanisms between polycyclic aromatic hydrocarbons (PAHs) and organic soil washing agents. Environ. Sci. Pollut. Res. 25, 299-311.
Gupta, H. (2015). Removal of phenanthrene from water using activated carbon developed from orange rind. Int. J. Sci. Res. Environ. Sci. 3, 248-255.
Hassett, J.J., Means, J. C., Banwart, W. L., Wood, S. G., Ali, S. and Khan, A. ( 1980). Sorption of dibenzothiophene by soils and sediments. J. Environ. Qual. 9, 184-186.
Hayes, M. H. B., MacCarthy, P., Malcolm, Jr., R. L. and Swift, S. (1990). Humic Substances II: In Search of Structure, Wiley-Interscience.
He, Y.W., Yediler, A., Sun, T.H. and Kettrup, A. (1995). Adsorption of fluoranthene on soil and lava-effects of the organic-carbon contents of adsorbents and temperature. Chemosphere 30, 141-150.
Hemond, H.F. and Fechner-Levy, E.J. (2014). Chemical Fate and Transport in the Environment, Academic Press.
Hiller, E., Jurkovic, L. and Bartal, M. (2008). Effect of
 
temperature on the distribution of polycyclic aromatic hydrocarbons in soil and sediment. Soil Water Res. 3, 231–240.
Hu, X.L., Liu, J.F., Mayer, P. and Jiang, G. (2008). Impacts of some environmentally relevant parameters on the sorption of polycyclic aromatic hydrocarbons to aqueous suspensions of fullerene. Environ. Toxicol. Chem. 27, 1868-1874.
Hu, Y., He, Y., Wang, X. and Wei, C. (2014). Efficient adsorption of phenanthrene by simply synthesized hydrophobic MCM-41 molecular sieves. Appl. Surf. Sci. 311, 825-830.
Hwang, S., N. Ramirez, T. J. Cutright, and L. K. Ju. (2003). The role of soil properties in pyrene sorption and desorption. Water Air Soil Pollut. 143,65-80.
Hwang, S.C. and Cutright, T.J. (2004). Adsorption/desorption due to system nonequilibrium and interaction with soil constituents. J. Environ. Sci. Health Part A 39, 1147–1162.
Jiao, H., Bian, G., Chen, X., Wang, S., Zhouang, X. and Bai, Z. (2017). Distribution, sources, and potential risk of polycyclic aromatic hydrocarbons in soils from an industrial district in Shanxi, China. Environ. Sci. Pollut. Res. 24, 12243-12260.
Jin, H., Zhou, W. and Zhu, L. (2013). Utilizing surfactants to control the sorption, desorption, and biodegradation of phenanthrene in soil-water system. J. Environ. Sci. 25, 1355-1361.
Jones, K.D. and Tiller, C.L. (1999). Effect of solution chemistry on the extent of binding of phenanthrene by a soil humic acid: a comparison of dissolved and clay bound humic. Environ. Sci. Technol. 33, 580-587.
Karickhoff, S. (1984). Organic pollutant sorption in aquatic systems. J. Hydraul. Eng. 110, 707-735.
Karickhoff, S.W., Brown, D.S. and Scott, T.A. (1979). Sorption of hydrophobic pollutants on natural sediments. Water. Res. 13, 241-248.
Kaschl, A., Römheld, V. and Chen, Y. (2002). Cadmium binding by fractions of dissolved organic matter and humic substances from municipal solid waste compost. J. Environ. Qual. 31, 1885 – 1892.
Kaya, E.M.O., Ozcan, A.S., Gok, O. and Ozcan, A. (2013). Adsorption kinetics and isotherm parameters of naphthalene onto natural and chemically modified bentonite from aqueous solutions. Adsorpt. 19, 879-888.
Killops, S.D. and Killops, V.J. (1993). An Introduction to Organic Geochemistry, Longman Scientific & Technical, John Wiley & Sons.
Kipling, J.J. (1965). Adsorption from Solution of Non-electrolytes. Academic Press, London.
Kobayashi, T. and Sumida, H., 2015. Effects of humic acids on the sorption and bioavailability of pyrene and 1,2-dihydroxynaphthalene. Soil Sci. Plant Nutr. 61, 113-122.
Laird, D.A. and Koskinen, W.C. (2008), Triazine soil interactions. In: LeBaron HM, McFarland JE, Burnside OC (Eds), 2008. The Triazine Herbicides 50 Years Revolutionizing Agriculture
Lakshman, M.K., Kole, P.L., Chaturvedi, S., Saugier, J.H., Yeh, H.J.C., Glusker, J.P., Carrell, H.L., Katz, A.K., Afshar, C.E., Dashwood, W-M., Kenniston, G. and Baird, W.M. (2000). Methyl group-induced helicity in 1,4-dimethylbenzo[c]phenanthrene and its metabolites: synthesis, physical, and biological properties. J. Am. Chem. Soc. 122, 12629-12636.
Lamichhane, S., Bal Krishna, K.C. and Sarukkalige, R. (2017). Surfactant-enhanced remediation of polycyclic aromatic hydrocarbons: A review. J. Environ. Manage. 199, 46-61.
Lemic, J., Tomasevic-Canovic, M., Adamovic, M., Kovacevic, D. and Milicevic, S. (2007). Competitive adsorption of polycyclic aromatic hydrocarbons on organo-zeolites. Microporous Mesoporous Mater. 105, 317-323.
Li, Y. and Gupta, G. (1994). Adsorption/desorption of hydrocarbons on clay minerals. Chemosphere 28, 628-637.
Liang, X., Guo, C., Liao, C., Liu, S., Wick, L.Y., Peng, D., Yi, X., Lu, G., Yin, H., Lin, Z. and Dang, Z. (2017). Drivers and applications of integrated clean-up technologies for surfactant-enhanced remediation of environments contaminated with polycyclic aromatic hydrocarbons (PAHs). Environ. Pollut. 225, 129-140.
Liang, X., Zhu, L. and Zhuang, S. (2016). Sorption of polycyclic aromatic hydrocarbons to soils enhanced by heavy metals: perspective of molecular interactions. J. soils sediments 16, 1509-1518.
 Ling, W., Sun, R.,  Gao, X.,  Xu, R. and Li, H. (2015), Low‐molecular‐weight organic acids enhance desorption of polycyclic aromatic hydrocarbons from soil. Eur. J. Soil Sci. 66, 339-347.
Lyman, W.J., Reehl, W.F. and Rosenblatt, D.H. (1990). Handbook of Chemical Property
Estimation Methods. 2nd printing. American Chemical Society, Washington, DC.
Maceiras, R., Alfonsin, V., Martinez, J., and de Rey, C. M. V. (2018). Remediation of Diesel-Contaminated Soil by Ultrasonic Solvent Extraction. Int. J. Env Res. 12, 651-659.
Mader, B.T., Goss, K.U. and Eisenreich, S.J (1997). Sorption of nonionic, hydrophobic organic chemicals to mineral surfaces. Environ. Sci. Technol. 31, 1079-1086.
Mao, X., Jiang, R., Xiao, W. and Yu, J. (2015). Use of surfactants for the remediation of contaminated soils: a review. J.  Hazard. Mater.  285, 419-35.
Marija, P., Dragana, P., Olga, K., Snežana, J., Dragan, Č., Pavle, P., and Miroslava, M. (2017). Evaluation of urban contamination with trace elements in city parks in Serbia using pine (Pinus nigra Arnold) needles, bark and urban topsoil. Int. J. Env Res.  11, 625-639.
Maturi, K. and Reddy, K. R. (2006). Simultaneous removal of organic compounds and heavy metals from soils by electrokinetic remediation with a modified cyclodextrin. Chemosphere 63, 1022-1031.
Maturi, K. and Reddy, K. R. (2008). Extractants for the removal of mixed contaminants from soils. Soil  Sediment Contam.  17, 586-608.
McCarty, P.L., Rittmann, B.E. and Reinhard, M. (1981). Trace organics in groundwater. Environ. Sci. Technol. 15, 40-51.
Means, J.C., Wood, S.G., Hassett, J.J. and Banwart, W.L. (1980). Sorption of polynuclear aromatic hydrocarbons by sediments and soils. Environ. Sci. Technol. 14, 1524-1528.
Morillo, E., Romero, A.S., Madrid, L., Villaverde, J. and Maqueda, C. (2008). Characterization and sources of PAHs and potentially toxic metals in urban environments of Sevilla (Southern Spain). Water Air Soil Pollut. 187, 41–51.
Muller, S., Totsche, K.U. and Kögel‐Knabner, I. (2007). Sorption of polycyclic aromatic hydrocarbons to mineral surfaces. Eur. J. Soil Sci. 58, 918–931.
Muñoz, B. and Albores, A. (2011). DNA damage caused by polycyclic aromatic hydrocarbons: mechanisms and markers. In: Chen, C. (ed.) Selected Topics in DNA Repair. InTech.
Nguyen, X.P., Cui,Y.J., Tang, A.M., Deng Y.F., Li, X.L. and Wouters, L. (2013). Effects of pore water chemical composition on the hydro-mechanical behavior of natural stiff clays. Eng. Geol. 166, 52-64.
Obuekwe, I.S. and Semple, K.T. (2013). Impact of Zn, Cu, Al and Fe on the partitioning and bioaccessibility of 14C-phenanthrene in soil. Environ. Pollut. 180, 180-189.
Olu-Owolabi, B.I., Diagboya, P.N. and Adebowale, K.O.  (2014). Evaluation of pyrene sorption-desorption on tropical soils. J. Environ. Manage.  137, 1-9.
Omores, R. A., Wewers, F., Ikhide, P. O., Farrar, T., and  Giwa, A. R. (2017). Spatio-temporal distribution of polycyclic aromatic hydrocarbons in Urban Soils in Cape Town, South Africa. Int. J. Env Res. 11, 189-196.
Osagie, E.I. and Owabor, C.N. (2015a). Adsorption of naphthalene on clay and sandy soil from aqueous solution. Adv. Chem. Eng. Sci.  5, 476-483.
Osagie, E.I. and Owabor, C.N. (2015b). Adsorption of pyrene from aqueous solution by clay and sandy soil. Adv. Chem. Eng. Sci.  5, 345-351.
Panagos, P., Van Liedekerke, M., Yigini, Y. and Montanarella, L. (2013). Contaminated sites in Europe: review of the current situation based on data collected through a European network. J. Environ. Public Health 158764.
Ping, L., Luo, Y., Wu, L.,Qian W., Song, J. and Christie, P. (2006). Phenanthrene adsorption by soils treated with humic substances under different pH and temperature conditions. Environ. Geochem. Health 28, 189-195.
Podoll, R.T., Irwin, K.C. and Parish, H.J. (1989). Dynamic studies of naphthalene sorption on soil from aqueous-solution. Chemosphere 18, 2399-2412.
Putra, E.K., Pranowo, R., Sunarso, J., Indraswati, N., and Ismadji, S. (2009). Performance of activated carbon and bentonite for adsorption of amoxicillin from wastewater: mechanisms, isotherms and kinetics. Water Res. 43, 2419-2430.
Raber, B., Kogel-Knabner, I., Stein, C., and Klem, D. (1998). Partitioning of polycyclic aromatic hydrocarbons to dissolved organic matter from different soils. Chemosphere 36, 79-97.
Rivas, J.F, García de la Calle, R., Alvarez, P. and Acedo B. (2008). Polycyclic aromatic hydrocarbons sorption on soils: some anomalous isotherm. J. Hazard. Mater. 158, 375-8.
Saeedi, M., Li, L.Y. and Grace, J.R. (2018a). Effect of organic matter and selected heavy metals on sorption of acenaphthene, fluorene and fluoranthene onto various clays and clay minerals. Environ. Earth. Sci. 77, 305.
Saeedi, M., Li, L.Y. and Grace, J.R. (2018b). Desorption and mobility mechanisms of co-existing polycyclic aromatic hydrocarbons and heavy metals in clays and clay minerals. J. Environ. Manage. 214, 204-214.
Saichek, R.E. and Reddy, K.R. (2005). Electrokinetically enhanced remediation of Hydrophobic Organic Compounds in soils: A Review. Crit. Rev. Environ. Sci. Technol. 35, 115-192.
Saison, C., Perrin-Ganier, C., Amellal, S., Morel, J.L. and Schiavon, M. (2004). Effect of metals on the adsorption and extractability of 14C-phenanthrene in soils. Chemosphere 55, 477–485.
Sales, P.S. and Fernandez, M.A. (2016). Synergism in the desorption of polycyclic aromatic hydrocarbons from soil models by mixed surfactant solutions. Environ. Sci. Pollut. Res. 23, 10158–10164.
 
Sánchez-Trujillo, M.A., Morillo, E., Villaverde, J. and Lacorte, S. (2013). Comparative effects of several cyclodextrins on the extraction of PAHs from an aged contaminated soil. Environ. Pollut. 178, 52-58.
Schwarzenbach, R.P. and Westall, J. (1981). Transport of nonpolar organic compounds from surface water to groundwater. Laboratory sorption studies. Environ. Sci. Technol. 15, 1360-1367.
Semple, K.T., Doick, K.J., Wick, L.Y. and Harms, H. (2007). Microbial interactions with organic contaminants in soil: definitions, processes and measurement: a review. J. Environ. Pollut. 150, 166-176.
Song, S., Zhu, L. and Zhou, W. (2008). Simultaneous removal of phenanthrene and cadmium from contaminated soils by saponin a plant-derived biosurfactant. Environ. Pollut. 156, 1368–1370.
Su, C., Jiang, L.Q. and Zhang, W.J. (2014). A review on heavy metal contamination in the soil worldwide: Situation, impact and remediation techniques. Environ. Skeptics Critics 3, 24-38.
Suffet, I. H. and MacCarthy,P. (1989.) Aquatic Humic Substances: Influence of Fate and Treatment of Pollutants. American Chemical Society.
Sun, D., Li, X. and Lou, L. (2010). On the Research of adsorption of polycyclic aromatic hydrocarbons (Phenanthrene) in soil-groundwater in Zhangshi irrigation district. Procedia Environ. Sci. 2, 824–83.
Tao, Y., Li, W., Xu, B., Zhong, J., Yao, Sh. And Wu, Q. (2013). Different effects of copper (II), cadmium (II) and phosphate on the sorption of phenanthrene on the biomass of cyanobacteria, J. Hazard. Mater. 261, 21– 28.
Thavamani, P., Megharaj, M., Krishnamurti, G.S.R., McFarland, R. and Naidu, R. (2011). Finger printing of mixed contaminants from former manufactured gas plant (MGP) site soils: implications to bioremediation. Environ. Int. 37, 184–189.
Thavamani, P., Megharaj, M. and Naidu, R. (2012). Multivariate analysis of mixed contaminants (PAHs and heavy metals) at manufactured gas plant site soils. Environ. Monit. Assess. 184, 3875–3885.
Traina, S.J., Spontak, D.A. and Logan, T. (1989). Effects of cations on complexation of naphthalene by water-soluble organic carbon. J. Environ. Qual. 18, 221-227.
Ukalska-Jaruga, A., Smreczak, B. and Klimkowicz-Pawlas, A. (2018). Soil organic matter composition as a factor affecting the accumulation of polycyclic aromatic hydrocarbons J. Soils Sediments 19, 1890-1900.
United Nations Environment Program (UNEP). (2012). GEO5 Global Environment Outlook, Environment for the Future We Want.
United States Environmental Protection Agency (USEPA). (2019). National priorities list. https://www.epa.gov/superfund/superfund-national-priorities-list-npl. Accessed Feb. 16, 2019.
United States Environmental Protection Agency (USEPA). (2018). https://www.epa.gov/cleanups/cleanups-where-you-live, Accessed 10, Feb. 2018.
United States Environmental Protection Agency (USEPA). (1993). Provisional Guidance for Quantitative Risk Assessment of PAH, EPA/600/R-93/089.Washington, DC.
United States Environmental Protection Agency (USEPA). (2008). Polycyclic Aromatic Hydrocarbons (PAHs). Available online at: http//www.epa.gov/wastes/hazard/Wastemin/minimize/factshts/pahs.pdf.
United States Environmental Protection Agency (USEPA). (2004). Cleaning up the Nation’s Waste Sites:  Markets and Technology Trends, Washington, DC.
Wahid, P.A. and Sethunathan, N. (1979). Sorption-desorption of .alpha., .beta., and .gamma. isomers of hexachlorocyclohexane in soils. J. Agric. Food Chem. 27, 1050-1053.
Walter, J. and Weber, W.J. Jr. (2002). Distributed reactivity model for sorption by soils and sediments: 15. High-concentration co-contaminant effects on phenanthrene sorption and desorption. Environ.  Sci. Technol. 36, 3625–3634.
Wan, J.,Wang, L., Lu, X., Lin, Y. and Zhang, S. (2011). Partitioning of hexachlorobenzene in a kaolin/humic acid/surfactant/water system: combined effect of surfactant and soil organic matter. J. Hazar. Mater. 196, 79-85.
Wang, G., Mielke, H., Quach, V., Gonzales, C. and Zhang, Q. (2004). Determination of polycyclic aromatic hydrocarbons and trace metals in New Orleans soils and sediments. Soil Sediment Contam. 13, 1–15.
Wang, G., Mielke, H., Quach, V., Gonzales, C. and Zhang, Q. (2004). Effects of carbonate and organic matter on sorption and desorption behavior of polycyclic aromatic hydrocarbons in the sediments from Yangtze River. J. Hazard. Mater. 154, 811-817.
Wang, G., Zhou, Y., Wang, X., Chai, X., Huang, L. and Deng, N. (2010). Simultaneous removal of phenanthrene and lead from artificially contaminated soils with glycine-ß-cyclodextrin. J. Hazard. Mater. 184, 690–695.
Wang, L., Niu, J., Yang, Z., Shen, Z. and Wang, J. (2008). Effects of carbonate and organic matter on sorption and desorption behavior of polycyclic aromatic hydrocarbons in the sediments from Yangtze River. J. Hazard. Mater. 154, 811-817.
Wang, J., Wang, C., Huang, Q., Ding, F. and He, X. (2015). Adsorption of PAHs on the sediments from the yellow river delta as a function of particle size and salinity. Soil Sediment Contam. 24, 103-115.
Weber, W.J. Jr., McGinley, P.M. and Katz, L.E. (1991), Sorption phenomena in subsurface systems: Concepts, models and effects on contaminant fate and transport. Water Res. 25, 499-528.
Weber, W.J. Jr., McGinley, P.M. and Katz, L.E. (1992). Distributed reactivity model for sorption by soils and sediments.1. Conceptual basis and equilibrium assessments. Environ.  Sci. Technol. 26, 1955-1962.
Wick, A.F., Haus, N.W., Sukkariyah, B.F., Haering, K.C. and Daniels, W.L. (2011). Remediation of PAH-contaminated soils and Sediments: a literature review. Virginia Polytechnic Institute and State University.
Weston, N.B., Giblin, A.E., Banta, G.T., Hopkinson, C.S. and Tucker, J. (2010). The effects of varying salinity on ammonium exchange in estuarine sediments of the parker river, Massachusetts. Estuaries Coasts 33, 985-1003.
Wolcott, A. R., Shin, Y-Oh. And Chodan, J. J. (1970). Adsorption of DDT by soils, soil fractions, and biological materials. J. Agric. Food Chem. 18, 1129-1133
Wu, P., Tang, Y., Wang, W., Zhu, N., Li, P., Wua, J., Dang, Z. and Wang, X. (2011). Effect of dissolved organic matter from Guangzhou landfill leachate on sorption of phenanthrene by Montmorillonite. J. Colloid. Interface Sci. 361, 618–627.
Yang, Y., Ratte, D., Smets, B.F., Pignatello, J.J. and Grasso, D. (2001). Mobilization of soil organic matter by complexing agents and implications for polycyclic aromatic hydrocarbon desorption. Chemosphere, 43, 1013-1021.
Yang, Y., Zhang, N., Xue, M. and Tao, S. (2010). Impact of soil organic matter on the distribution of polycyclic aromatic hydrocarbons (PAHs) in soils. Environ. Pollut. 158, 2170-2174.
Yang, L., Jin, M., Tong, C. and Xie, S. (2013). Study of dynamic sorption and desorption of polycyclic aromatic hydrocarbons in silty-clay soil. J. Hazard. Mater.  244-245, 77-85.
Yaron, B., Swoboda, A.R. and Thomas, G.W. (1967). Aldrin adsorption by soils and clays. J. Agric. Food Chem. 15, 671–67.
Yeom, I.T., Ghosh, M.M. and Cox, C.D. (1996). Kinetic aspects of surfactant solubilization of soil-bound polycyclic aromatic hydrocarbons. Environ. Sci. Technol.30, 1589-1595.
Yu, H.,   Xiao, H. and Wang, D. (2014). Effects of soil properties and biosurfactant on the behavior of PAHs in soil-water systems. Environ. Sys. Res. 3, 6.
Zeledon-Toruno, Z.C., Lao-Luque, C., de Las Heras, F.X. and Sole-Sardans, M. (2007). Removal of PAHs from water using an immature coal (leonardite). Chemosphere 67, 505-512.
Zhang, M.K. and Ke, Z.X. (2004).  Copper and zinc enrichment in different size fractions of organic matter from polluted soils. Pedosphere 14, 27–36.
Zhang, W., J. Cao, H. Huang, and R. Zhang. (2010). Effect of coexisting lead and phenanthrene on their individual sorption on a clayish soil. Soil Sediment Contam. 19, 322-337.
Zhang, W., Zhuang, L., Yuan, Y., Tong, L. and Tsang, D.C.W. (2011). Enhancement of phenanthrene adsorption on a clayey soil and clay minerals by coexisting lead or cadmium. Chemosphere 83, 302–310.
Zhang, L.C., Luo, L. and Zhang, S.Z. (2011). Adsorption of phenanthrene and 1,3-dinitrobenzene on cation-modified clay minerals. Colloids Surf. Physicochem. Eng. Asp. 377, 278-283.
Zhang, W., Zheng, J., Zheng, P., Tsang, D.C.W. and Qiu, R. (2015). The roles of humic substances in the interactions of phenanthrene and heavy metals on the bentonite surface. J. Soils Sediments 15, 1463–1472.
Zhou, W. and Zhu, L. (2007). Efficiency of surfactant-enhanced desorption for contaminated soils depending on the component characteristics of soil-surfactant PAHs system. . Environ. Pollut. 14, 66-73.
Zhu, D., Herbert, B.E., Schlautman, M.A., Carraway, E.R. and Hur, J. (2004). Cation-Pi  bonding: a new perspective on the sorption of polycyclic aromatic hydrocarbons to mineral surfaces. J. Environ. Qual. 33, 1322-1330.