Two-stage desorption kinetics and in situ partitioning of hexachlorobenzene and dichlorobenzenes in a contaminated sediment

Electrokinetic movement of hexachlorobenzene in clayed soils enhanced by Tween 80 and β-cyclodextrin

“…Researchers have investigated the remediation of HCBcontaminated soils by microbial dechlorination [4][5][6][7][8], enhanced desorption [9][10][11][12][13] and physicochemical processes such as dechlorination by metal alloy [14], sonochemistry [15], radiation [16], photochemistry [17] and zero-valent iron [18]. However, microbial dechlorination requires highly selectivity bacteria or plants and is time-consuming.…”

Environmental bioavailability of hydrophobic organochlorines in sediments—A review

“…Physical and chemical interactions of HOCs with soil/sediment (geosorbents) often result in strong binding and slower subsequent release rates.The commonly observed nonlinear biphasic desorption phenomena include an initial rapid and reversible desorption of a labile HOC (sorbate) fraction, followed by a slow-desorbing or desorptionresistant, nonlabile fraction, which can account for up to 98 percent of the total concentration (Cornelissen et al, 1997a;Schlebaum et al, 1999).The biphasic desorption kinetics indicated that contaminant availability and toxicity cannot be assessed simply based on total contaminant concentrations, because the slow-desorbing fraction that is strongly bound to soil/sediment has limited availability.The desorption rate is limited by Although aging in soil and sediment reduces bioavailability and thus toxicity, it does not entirely eliminate toxicity.…”

“…Solid phase extraction (SPE) approaches are often used in the assessment of the multiphasic desorption kinetics and equilibrium partitioning for sediment/soil-bound HOCs (Cornelissen et al, 1997a;Krauss & Wilcke, 2001;Macrae & Hall, 1998;Morrison et al, 2000). SPE uses a low-density solid supersorbent, which has a high affinity for HOCs.…”

“…The added sorbent is periodically separated from the slurry and replaced with fresh material.The sorbent, which has been separated from the slurry, is then thermally desorbed on a gas chromatograph to quantify the desorbed HOC. By conducting temporal measurements, the fast-, slow-, and very slow-desorbing fractions in the soil and sediment can be determined (Cornelissen et al, 1997b;Ghosh et al, 1999;Hawthorne et al, 2002;Opdyke & Loehr, 1999;van Noort et al, 2003).The fast-desorbing fractions (presumably bioavailable) were found to be well correlated with the PAH biodegradation and earthworm assimilation of chlorinated pesticides in soils (Cornelissen et al, 1997a;Morrison et al, 2000;. In contrast, Leppanen et al (2003), found that Tenax extraction of sediment-associated 3,4,3´,4´-tetrachlorobiphenyl for the fast desorbing fraction did not correlate well with, but overestimated, the bioaccumulation by benthic invertebrates (Lumbriculus variegatus, Chironomus tentans, and Hyalella azteca).…”

“…H x CB and PCDD/Fs have been found to bioaccumulate in fish and invertebrates (Cornelissen et al, 1997a;Russell et al, 1999;Sijm & van der Linde, 1995). Bioaccumulation may lead to detrimental effects on the benthic community, while these impacts are often not observed in conventional acute toxicity tests.…”