DESORPTION-RESISTANCE OF CHLOROBENZENE AND PHENANTHRENE IN WETLAND PEAT SOILS

Shin, Won Sik

Environmental Engineering Research 2000;5(1): 23-33.

Department of Civil and Environmental Engineering & Hazardous Waste Research Center, Louisiana State University, Baton Rouge, LA 70803-7511, USA

Corresponding Author: Won Sik Shin ,

Received: December 6, 1999; Accepted: March 3, 2000.

ABSTRACT

Sorption/desorption study was conducted to determine desorption-resistance of organic compounds in recent deposited organic matter by studying wetland soils explicitly. Sorption/desorption characteristics for both surface marsh soil (top 0 — 2 cm, <5 years old) and deeper marsh soil (below 10 —cm, >20 years old) were investigated to see if soil age can cause differences in sorption/desorption in wetlands. Measurements of organic matter age were conducted using several techniques including the ratio of elemental oxygen to carbon in the organic matter. Sorption/desorption of organic compounds (chlorobenzene and phenanthrene) in recently deposited freshwater marsh soils was determined using a batch desorption procedure¹⁾ and compared with relatively "'older" soils. Sorption was biphasic with about 30-62% (chlorobenzene) and 46.7 — 82.9% (phenanthrene) of the adsorbed mass residing in the desorption-resistant fraction after 7 — 14 desorption steps. Sorption/desorption parameters were determined for several models to explain the desorption resistance including the Tomson-Kan model, slow sorption model and dual reactive domain model (DRDM). All models indicated the presence of appreciable desorption-resistant phase in wetland peat soils and an increase in the size of the desorption-resistance in "older" organic matter. A case study of the implications of desorption-resistance in wetland remediation was presented based on the Petro Processors, Inc. Superfund site Devil's Swamp wetland.