Changes in Dissolved Organic Carbon of Soil Amendments with Aging:  Effect on Pesticide Adsorption Behavior

Abstract

The effect of aging in the soil of three organic amendments (OAs), one liquid (LF) and two solid ones (SF and AL), has been investigated and related to changes in soil adsorption of metalaxyl and tricyclazole. LF and AL have very high dissolved organic carbon (DOC) contents with low humification index values, whereas SF has a low DOC content but the highest amounts of highly humified material. All OAs increased the adsorption of tricyclazole, whereas adsorption of metalaxyl decreased in soils amended with LF and AL, due to competition with DOC for mineral adsorption sites. With aging, DOC from SF amended soils is not significantly affected and neither is adsorption behavior. On the contrary, the great reduction of DOC from LF and AL with aging has been shown to affect adsorption of metalaxyl and tricyclazole, and this effect is dependent on the pesticide, the nature of the DOC, and the type of soil, in particular its clay mineralogy.

Assisted attenuation of a soil contaminated by diuron using hydroxypropyl-β-cyclodextrin and organic amendments

“…These amounts are 4.6 times higher than that obtained when only micronutrients were applied in the soil (0.96%, Fig. 2), and this increases because of the formation of DOM-diuron complexes as observed previously (Thevenot et al, 2008;Cox et al, 2004;El Imache et al, 2012). Although SS and USR supply different DOM concentrations to soil (0.28 and 0.04 mg DOM/g of soil, respectively), a similar diuron extraction was obtained, indicating that the quality of DOM supplied plays also an important role in diuron availability.…”

Characterization and selection of biochar for an efficient retention of tricyclazole in a flooded alluvial paddy soil

“…The isotherms exhibit increasing non-linearity with AC, B4, and the mixture amendment, corresponding to the increasing deviation from 1 of ŋ f values in the Freundlich model (Table 6). This suggests a significant solute adsorption on a small amount of a high-surface area material in soil and to specific interactions of tricyclazole with highly reactive sites provided for the organic matter from the amendment, supporting previous results obtained with other amendments and other sorbents [61,68]. The curvilinear isotherm indicates that the number of available sites for the adsorption turned into a limiting factor at the higher concentrations of tricyclazole.…”

Elaboration, characteristics and advantages of biochars for the management of contaminated soils with a specific overview on Miscanthus biochars

“…They observed a lower sorption of pesticides with macadamia nut shell biochar compared to wood chip pellet biochar. This result was attributed to the higher content of dissolved organic carbon in this biochar, which can compete with pesticides for mineral soil surfaces and thus decrease pesticide sorption (Cox et al, 2004). Martin et al (2012) observed differences in the sorption capacity between biochars freshly spread or in place for 3 years.…”