Effect of Aerobic and Anaerobic Conditions on Chlorophenol Sorption in Wetland Soils

Abstract

ant between the solid phase and dissolved phase (sorption), which is governed by the physical and chemical Sorption of four chlorophenols (CPs) was studied in ten wetland properties of the solute, the sorbent, and the solvent. soils with organic C contents between 1 and 44%, which were incu-Much research on organic pollutant sorption has dembated under aerobic or anaerobic conditions to simulate wetland conditions. The objectives of the study were to (i) determine the influence onstrated a strong link between the distribution ratio of aerobic and anaerobic processes on sorption, and (ii) develop sorp-(K p) and the lipophilicity of hydrophobic organic polluttion models to predict the distribution coefficient based on chemical ants, as expressed by its K ow , and the fractional amount characteristics of soils and compounds. Aerobic soils consistently had of organic C of the sorbent (f oc): lower pH than anaerobic treatments, which was a function of the amount of oxidizable constituents present in the sample. Depending K p ϭ f oc ϫ a(K ow) b [1] on the pK a of the compound relative to the pH shift, a greater fraction where a and b are empirical constants that differ deof the CP was in the neutral form in the aerobic treatments, which pending primarily on the nature of the pollutant. The was sorbed to a much greater extent than the ionic form (by about relationship has been very useful for predicting sorption 25 times). The organic C normalized distribution coefficient (K oc) was of many hydrophobic organic pollutants by a wide varistrongly related to the octanol-water distribution coefficient (K ow) and soil pH. Sorption models accurately predicted distribution coefficients ety of sorbents; on occasion, however, it has been found within a factor of 2 from the K ow and pK a of the compounds and the to be deficient for ionizable organic compounds such pH and organic C content of the sorbent. The role of sorption on CP as CPs. retention was partially negated by the formation of the nonseparable In studies on the sorption of CPs in soils and sediphase, which composed up to 8.6% of the total solid mass (depending ments, Schellenburg et al. (1984) and Lagas (1988) on the soil redox status) and had similar distribution coefficients as found that the model for hydrophobic compounds had the separable phase. This study demonstrated that microbial redox limited application because it did not account for the processes significantly influenced the soil properties and CP retention contribution of both the neutral species and the phecharacteristics, and should be considered when designing a bioremedinolate anion to overall sorption. Shimizu et al. (1992) ation plan for these compounds. derived a model that accounted for the contribution of both species to the distribution coefficient of PCP (pK a ϭ 4.74

Effect of lead on the sorption of 2,4,6-trichlorophenol on soil and peat

“…Such a mechanism was supported by Angelo and Reddy (2003), who found that the colloidal phase could enhance the water solubility of chlorophenols. In the present study, the presence of lead decreased not only the DOC contents (Table 2), but also the sorption of 2,4,6-TCP (Fig.…”

“…Due to its high toxicity, carcinogenic properties, and persistence in the environment, much attention has been focused on its sorption-desorption behavior . Angelo and Reddy (2003) studied the sorption of 2, 3,4,5-tetrachlorophenol, 3,4,5-trichlorophenol, 3,5-dichlorophenol and pentachlorophenol on soils under aerobic and anaerobic conditions, and found that hydrophobic interaction was the dominant sorption mechanism in the wetland soils. 3,5-Dichlorophenol was easily sorbed on high-organiccontent peat soil and the nonlinearity of isotherms was attributed to the specific interactions between the polar group of 3,5-dichlorophenol and soil organic matter (Chiou and Kile, 1998).…”

“…Compared with the extensive separate studies on the sorption of heavy metals (Xia et al, 1997;Strawn and Sparks, 1999) or organic contaminants in soils and sediments (Chiou and Kile, 1998;Angelo and Reddy, 2003), there is little information on the effect of heavy metals on the sorption of organic contaminants and vice versa (Morillo et al, 2002;Xu et al, 2005). However, it should be realized that lead and 2,4,6-TCP may occur together in field irrigated by wastewater.…”

Redox Potential and Seasonal Porewater Biogeochemistry of Three Mountain Wetlands in Southeastern Kentucky, USA

“…However, correlations of pH with Fe 2+ and SO 4 2-(r = 0.61** and 0.67**, respectively) that occurred only during summer suggested that interactions with Fe 2+ or SO 4 2-possibly influenced the significantly lower (P \ 0.05) summer pH. Redox conditions that promote the oxidation of reduced constituents (i.e., organic matter, H 2 S, NH 4 + , or Fe 2+ ) can decrease pH (D'Angelo and Reddy 2003). During the interval between spring and summer porewater sampling periods, Eh measured at the 60 cm depth increased from -98 mV to -54 mV, and Eh at 90 cm increased from -159 mV to -46 mV (Fig.…”

Sorption of p‐nitrophenol on two Chinese soils as affected by copper

“…The adsorption of atrazine and linuron on natural colloids was 10-to 35-fold greater than that on soils and sediments [17]. The colloidal phase enhanced the water solubility of four chlorophenols [18] and facilitated the transport of contaminants [19]. Based on separate studies concerning the adsorption of metals and HOCs, it has been generally believed that metals and HOCs are preferentially adsorbed at different sites.…”