First evidence for covalent linkage of acidic metabolites of metalaxyl and DDT as non-extractable pesticide residues in soil and sediment

Kalathoor, Roschni; Zeiner, Miriam; Schmidt, Burkhard; Schäffer, Andreas; Schwarzbauer, Jan

doi:10.1007/s10311-015-0514-6

Cited by 18 publications

(10 citation statements)

References 13 publications

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“…For instance, molecular level 13 C-tracing has allowed to evidence the occurrence of temporal pools of the same organic compound in various fractions of the same soil sample (Lichtfouse et al 1998;Lichtfouse 1999Lichtfouse , 2012. Moreover, cleavage of sedimentary matter with Na 18 OH has shown that DDT metabolites are bound to organic macromolecules (Kalathoor et al 2015). A better knowledge of binding mechanisms would help to design remediation techniques such as extraction (Karasali and Pavlidis 2021).…”

Section: Bound Residuesmentioning

confidence: 99%

Pesticide resurrection

et al. 2021

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Section: Bound Residuesmentioning

confidence: 99%

Pesticide resurrection

et al. 2021

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“…The incorporation of DDXs into natural solid particles as nonextractable residues can be (i) strong adsorption on solid surfaces as well as on the structural pores (e.g., van-der Waals forces and ionic interactions), (ii) physical entrapment in the solid matrix structures, or (iii) bondage to the organic macromolecules via covalent linkages with functional groups (e.g., carboxylic, hydroxyl, amino and carbonyl groups). , These incorporation mechanisms and potential releasing pathways of covalently bound DDXs as well as the detection of corresponding products are illustrated in Figure . The formation of NER-DDA with sediment organic matter has already been proved to be via ester bonds . As mentioned above, DDMUBr was likely released when an ether bond between DDNU and the organic matrix was broken by BBr 3 , DBP might have been formed after the attack of carbon–carbon double bonds by RuO 4 , and DDPU and DDPS were suggested to be released after carbon–carbon bond cleavage by TMAH thermochemolysis .…”

Section: Results and Ddiscussionmentioning

confidence: 92%

“…Sequential chemical degradation has been applied since 2003 to release sedimentary bound DDXs, and a variety of DDT metabolites have been detectable as NER. − More recently, pyrolysis and thermochemolysis have been conducted to obtain further DDT derivatives . Covalent linkage of DDA (dichlorodiphenylacetic acid) to soil and sediment, which forms NER-DDA was proved by Kalathoor et al in 2015 . Current knowledge on the fate of NER-DDXs (data on their formation are restricted to field samples), especially those beside DDT, DDD, and DDE, in natural solid ambient is quite limited, and there is even less research with respect to the aquatic-terrestrial pathway since most of the aforementioned studies solely considered sediment and/or soil.…”

Section: Introductionmentioning

confidence: 99%

Formation and Fate of Point-Source Nonextractable DDT-Related Compounds on Their Environmental Aquatic-Terrestrial Pathway

Zhu

Dsikowitzky

Kucher

et al. 2019

Environ. Sci. Technol.

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Nonextractable residues (NER) are pollutants incorporated into the matrix of natural solid matter via different binding mechanisms. They can become bioavailable or remobilize during physical−chemical changes of the surrounding conditions and should thus not be neglected in environmental risk assessment. Sediments, soils, and groundwater sludge contaminated with DDXs (DDT, dichlorodiphenyltrichloroethane; and its metabolites) were treated with solvent extraction, sequential chemical degradation, and thermochemolysis to study the fate of NER-DDX along different environmental aquatic-terrestrial pathways. The results showed that DDT and its first degradation products, DDD (dichlorodiphenyldichloroethane) and DDE (dichlorodiphenyldichloroethylene), were dominant in the free extractable fraction, whereas DDM (dichlorodiphenylmethane), DBP (dichlorobenzophenone), and DDA (dichlorodiphenylacetic acid) were observed primarily after chemical degradation. The detection of DDA, DDMUBr (bis(p-chlorophenyl)bromoethylene), DDPU (bis(p-chlorophenyl)-propene) and DDPS (bis(p-chlorophenyl)-propane) after chemical treatments evidenced the covalent bindings between these DDXs and the organic matrix. The identified NER-DDXs were categorized into three groups according to the three-step degradation process of DDT. Their distribution along the different pathways demonstrated significant specificity. Based on the obtained results, a conceptual model of the fate of NER-DDXs on their different environmental aquatic-terrestrial pathways is proposed. This model provides basic knowledge for risk assessment and remediation of both extractable and nonextractable DDT-related contaminations.

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“…In cases where type II NER has been unambiguously demonstrated, cleaving of covalent ester-bonds by labelled water (H 2 18 O) or sodium hydroxide (Na 18 OH) can clearly prove covalent binding as shown for the transformation/degradation products of DDT and metalaxyl which were bound by ester-linkage to humic matter [52]. However, other types of covalent bonds, like Michael adducts or Schiff base adducts, cannot be investigated by this methodology.…”

Section: Recommendations For Further Researchmentioning

confidence: 99%

A unified approach for including non-extractable residues (NER) of chemicals and pesticides in the assessment of persistence

2018

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All chemicals form non-extractable residues (NER) to various extents in environmental media like soil, sediment, plants and animals. NER can be quantified in environmental fate studies using isotope-labeled (such as 14C or 13C) tracer compounds. Previous NER definitions have led to a mismatch of legislation and state of knowledge in research: the residues are assumed to be either irreversibly bound degradation products or at least parts of these residues can be released. In the latter assumption, soils and sediments are a long-term source of slowly released residues. We here present a conceptual experimental and modeling approach to characterize non-extractable residues and provide guidance how they should be considered in the persistence assessment of chemicals and pesticides. Three types of NER can be experimentally discriminated: sequestered and entrapped residues (type I), containing either the parent substance or xenobiotic transformation products or both and having the potential to be released, which has indeed been observed. Type II NER are residues that are covalently bound to organic matter in soils or sediments or to biological tissue in organisms and that are considered being strongly bound with very low remobilization rates like that of humic matter degradation rates. Type III NER comprises biogenic NER (bioNER) after degradation of the xenobiotic chemical and anabolic formation of natural biomolecules like amino acids and phospholipids, and other biomass compounds. We developed the microbial turnover to biomass (MTB) model to predict the formation of bioNER based on the structural properties of chemicals. Further, we proposed an extraction sequence to obtain a matrix containing only NER. Finally, we summarized experimental methods to distinguish the three NER types. Type I NER and type II NER should be considered as potentially remobilizable residues in persistence assessment but the probability of type II release is much lower than that of type I NER, i.e., type II NER in soil are “operationally spoken” irreversibly bound and can be released only in minute amounts and at very slow rates, if at all. The potential of remobilization can be evaluated by chemical, physical and biological methods. BioNER are of no environmental concern and, therefore, can be assessed as such in persistence assessment. The general concept presented is to consider the total amount of NER minus potential bioNER as the amount of xenoNER, type I + II. If a clear differentiation of type I and type II is possible, for the calculation of half-life type I NER are considered as not degraded parent substance or transformation product(s). On the contrary, type II NER may generally be considered as (at least temporarily) removed. Providing proof for type II NER is the most critical issue in NER assessment and requires additional research. If no characterization and additional information on NER are available, it is recommended to assess the total amount as potentially remobilizable. We propose our unified approach of NER characterizati...

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First evidence for covalent linkage of acidic metabolites of metalaxyl and DDT as non-extractable pesticide residues in soil and sediment

Cited by 18 publications

References 13 publications

Pesticide resurrection

Pesticide resurrection

Formation and Fate of Point-Source Nonextractable DDT-Related Compounds on Their Environmental Aquatic-Terrestrial Pathway

A unified approach for including non-extractable residues (NER) of chemicals and pesticides in the assessment of persistence

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