The Role of Lipids on Sorption Characteristics of Freshwater‐ and Wastewater‐Irrigated Soils

Abstract

The soil lipid fraction can play an important role in the sorption of organic compounds. In this study, the impact of the lipid fraction of freshwater-and wastewater-irrigated soils on the sorption of non-and relatively polar compounds was assessed. Lipid analyses revealed a clear difference between the two lipid fractions. The lipid extract from the wastewater-irrigated soil was consistent with mainly straight paraffinic chain materials; the lipid extract from freshwater-irrigated soil, on the other hand, exhibited stronger signals of aromatics, double bonds, ester, ether, and methyl, in addition to a smaller contribution from methylene protons. Our data suggest that lipid removal induced a stronger increase in the soil's sorption affinity for solutes capable of polar interactions such as atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) and chlorotoluron (N9-(3-chloro-4-methylphenyl)-N,N-dimethylurea) as compared to phenanthrene. Moreover, the level of increase in sorption affinities due to lipid removal was much higher for the freshwater-irrigated soil than for its wastewater-irrigated counterpart, even though the level of lipids in the freshwater-irrigated soil was half that in the wastewater-irrigated one (6 vs. 11% of the total organic C). The higher level of polar functionalities, such as ether and ester moieties, in the lipid fraction from the freshwater-irrigated soil suggests that these extractable compounds compete successfully with the polar solutes (atrazine and chlorotoluron) for specific binding sites in the soil organic matter (SOM). It appears that the composition of the lipid fraction may be a key consideration in unraveling the sorption of organic molecules in soils.

Sorption of polyaromatic compounds by organic matter-coated Ca2+– and Fe3+–montmorillonite

“…3): K OC ranged from 9082 ± 321 to 1381 ± 149 for HA-Fe 3+ -clay vs. 1890 ± 163 to 1137 ± 89 for wax-Fe 3+ -clay. This is in accordance with Drori et al (2006), who demonstrated that the presence of lipids decreases the affinity of polar solutes to soils.…”

Effects of humic acid and lipid on the sorption of phenanthrene on char

“…Results obtained by Rice (1999), andTrembly et al (2005) showed that after extraction of lipid from sediment and humin, the sorption capacity of phenanthrene increased drastically, and the nonlinearity of the sorption isotherms was much more pronounced, thereby revealing the important role of lipid in the HOC sorption. However, Drori et al (2006Drori et al ( , 2008 found that phenanthrene sorption was not significantly affected by lipid removal. Lipids were better competitors for sorbates capable of polar interactions than for phenanthrene.…”

Fertilization and irrigation practice as source of microorganisms and the impact on nematodes as their potential vectors

“…This suggests that common properties of urban organic wastes alter the chemical and biochemical environment for the soil inhabiting microorganisms in a similar manner. For example Herre et al (2004) showed that irrigation water quality affected organic matter, Cd and Cu mobility in soil, and Drori et al (2006) reported altered levels of polar functionalities that can impair microbial transport and dispersal. In sum, the results indicate that the joint origin of wastewater and sewage sludge results in a greater similarity of microbial communities in comparison to freshwater irrigation or manure application.…”

“…Distribution of these pathogens takes place via active movement as microorganisms are able to migrate significant distances through the soil in vertical as well as horizontal direction (Abu-Ashour et al, 1994). Moreover, bacterial dispersal can be enhanced by irrigation practice in arable land as long-term application of treated wastewater alters soil sorption capabilities (Drori et al, 2006), which in turn affects microbial absorption and transport.…”