Organic pollutants associated with macromolecular soil organic matter: Mode of binding

Effect of microbial activity, soil water content and added copper on the temporal distribution patterns of HCB and DDT among different soil organic matter fractions

“…Although there is growing observations of the role of microorganisms on the sequestration or mass transfer of HOCs in soil, the mechanisms are not fully understood. The possible mechanisms may be ascribed to the partial transformation (Richnow et al, 1997) and/or the carbon turnover activities by the soil microbial communities (Guthrie and Pfaender, 1998;Richnow et al, 1998;Howsam et al, 2001). 3.3.…”

Isotopic constraints on the sources and associations of organic compounds in marine sediments

“…Once incorporated into sediments, HOCs are subject to varied and complex processes that confound our understanding of their ultimate fate. For example, laboratory (Richnow et al, 1997(Richnow et al, , 1998(Richnow et al, , 2000Hatcher et al, 1993) and field studies (Beller et al, 1998;Richnow et al, 1994;Reddy et al, 2000;Schwarzbauer et al, 2003) have shown that certain HOCs (or their metabolites) can bind to natural organic matter, but this process is not easy to follow and is especially difficult to quantify using current analytical approaches. These associations are, however, of interest as they can potentially affect the bioavailability, toxicity, transport and long-term fate of HOCs (Alexander, 1995).…”

“…Much of the work to date has focused on soils contaminated with polycyclic aromatic hydrocarbons (PAHs) (Richnow et al, 1994(Richnow et al, , 1995(Richnow et al, , 1997(Richnow et al, , 1998(Richnow et al, , 1999(Richnow et al, and 2000 and other HOCs such as pesticides (Gevao et al, 2000 and references therein), fumigants , the fungicide cyprodinil , 2,4,6-trinitrotoluene (TNT) (Eriksson et al, 2004), and polychlorinated biphenyls (PCBs) (Kohl and Rice, 1998). Experimental and analytical techniques for determining the presence of bound HOCs and their residues vary (Northcott and Jones, 2000 and references therein), but in most instances, specific interactions are determined by sequential chemical treatments.…”

“…Subsequent chemical treatments performed on the remaining extracted soil residues or humic fractions target linkages by specific types of covalent bond between HOCs and OM. Alkaline or acid hydrolysis methods are specifically aimed at cleaving ester bonds (Richnow et al, 1994(Richnow et al, , 1997(Richnow et al, , 1998(Richnow et al, and 2000, and harsher degradation techniques such as boron trichloride degradation and hydrogenolysis with rhodium-on-charcoal target ether as well as ester linkages (Richnow et al, 1994). Analytical pyrolysis and thermal desorption methods have also been employed to release compounds associated by carbon-carbon bonds as well as other bonds (Richnow et al, 1995;Northcott and Jones 2000, and references therein).…”

“…In petroleum contaminated sediments, PAHs such as naphthalene and phenanthrene and their alkylated derivatives are of interest due to their toxicity to organisms, as well as the potential of their corresponding metabolic intermediates to bind to OM (Richnow et al, 1994(Richnow et al, , 1995(Richnow et al, , 1997(Richnow et al, , 1998(Richnow et al, , 1999(Richnow et al, , 2000. The structure of the parent All of these HOCs and/or their metabolites, have a variety of functional groups and therefore potential reactive sites ("chemical handles") to bind to OM.…”