Sorption of nonpolar organic chemicals on low‐carbon‐content aquifer materials

Abstract

Sorption isotherms were measured by batch equilibration methods for three nonpolar organic sorbates on seven subsurface, low‐carbon sedimentary aquifer materials. Radiolabeled (14C) 1‐methylnaphthalene, o‐dichlorobenzene and naphthalene were separately equilibrated with the sorbents to determine sorption coefficients (K). Chemical and physical properties of the aquifer materials were determined. Possible relationships between sorption coefficients and organic carbon (OC) content and other sorbent properties were investigated using multivariate statistics. Sorbent properties used in the statistical analysis were sorption coefficients, percentage OC, percentage sand, percentage clay, percentage silt, specific surface area, cation exchange capacity, percentage 1:1 clay, percentage 2:1 clay and percentage iron content. No predictive relationships between sorption coefficients and aquifer material properties were found. The sorption coefficient does not correlate with any of the properties of the aquifer materials, including OC content for aquifer materials with OC content of less than 0.10%. It is recommended that sorption coefficients be determined experimentally on each different aquifer material for use in ground water transport calculations.

Sorption, degradation and mobility of microcystins in Chinese agriculture soils: risk assessment for groundwater protection

“…The leaching potential of organic pollutants such as pesticides are usually assessed by the normalized distribution of the soil organic carbon partition coefficient (K oc ) (Wauchope Stauffer et al, 1989), GUS parameters (Gustafson, 1989) and laboratory column leaching (OECD, 2003;Oppel et al, 2004). K oc values of three MC variants were calculated from their K d values in the three soils, the average values for MC-RR, LR and Dha 7 LR were 224, 46.3 and 84.8 respectively (Table 3).…”

Mass removal and low-concentration tailing of trichloroethene in freshly-amended, synthetically-aged, and field-contaminated aquifer material

“…First, the generally lower fractions of total organic carbon may result in multiple components (e.g., organic matter plus mineral fractions) contributing to the sorption uptake of hydrophobic organic compounds. For example, Stauffer et al (1989) reported that the uptake of naphthalene and 1,2-dichlorobenzene by aquifer materials with low organic-carbon contents ( f oc < 0.10%) correlated well with organic carbon, silt, cation exchange capacity, and 1:1 clay content. Second, as a result of geological maturation, chemically-reduced, physically-condensed carbonaceous material (e.g., kerogen, unburned coal, and soot) may become more prominent and thus play an even more significant role in the uptake of hydrophobic organic compounds for these low organic-carbon-content aquifer materials.…”

Sorption of Non-ionic Aromatic Organics to Mineral Micropores: Interactive Effect of Cation Hydration and Mineral Charge Density

“…Molecular-scale chemical and biochemical processes at mineral–water interfaces (MWIs) play important roles in the fate and transport of contaminants in soils and sediments. For soils and sediments with low organic carbon (<0.1%), sorption of contaminants into the mineral phase is commonly assumed to be the major mechanism for contaminant retention. − In particular, clay minerals, such as smectites, palygorskite, and zeolites, are critical players in the transport and fate of contaminants and have drawn significant attention as suitable materials for environmental remediation. − …”