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Classifying NOM-organic sorbate interactions using compound transfer from an inert solvent to the hydrated sorbent
Mikhail Borisover1, Ellen R Graber
1Institute of Soil, Water and Environmental Sciences, The Volcani Center, ARO, Bet Dagan 50250 Israel. vwmichel@volcani.agri.gov.il
Environmental Science & Technology
|January 14, 2004
Summary
This study introduces a novel method to quantify organic compound interactions with natural organic matter (NOM). It reveals significant variations in sorption strength, classifying compounds based on their interaction potential with NOM.
Area of Science:
- Environmental Chemistry
- Soil Science
- Organic Geochemistry
Background:
- Natural organic matter (NOM) plays a crucial role in the environmental fate and transport of organic compounds.
- Understanding the sorption mechanisms of organic compounds to NOM is essential for predicting their behavior in ecosystems.
- Existing methods for assessing sorption can be limited by reference medium inconsistencies.
Purpose of the Study:
- To develop and apply a new approach for quantifying organic compound interactions with model NOM.
- To classify organic compounds based on the strength of their interactions with NOM.
- To investigate the relationship between sorption strength and sorption nonlinearity.
Main Methods:
- A novel method was employed, converting aqueous sorption to compound transfer from n-hexadecane to hydrated NOM.
- This approach utilizes a consistent inert reference medium (n-hexadecane) for all compounds.
- Sorption nonlinearity was assessed by examining the distribution coefficient (K(d,i)) as a function of sorbed concentration.
Main Results:
- Organic compound interactions with NOM varied significantly, spanning 4-5 orders of magnitude in strength.
- Compounds with strong hydrogen-bonding potentials exhibited the strongest interactions with NOM.
- Aliphatic hydrocarbons and their chlorinated analogues showed greater distribution to NOM than aromatic compounds.
- Significant sorption nonlinearity, indicated by a decrease in K(d,i) with increasing sorbed concentration, was observed only for compounds with the strongest NOM interactions.
Conclusions:
- The developed method allows for robust classification of sorbate-NOM interaction strengths.
- Sorption nonlinearity is primarily associated with strong organic compound-NOM interactions.
- The relationship between interaction strength and nonlinearity can characterize compound distribution across different sorption domains within NOM.