Fate of phenanthrene and mineralization of its non-extractable residues in an oxic soil

Wang, Yongfeng; Xu, Jun; Yan, Xiaoyuan; Ma, Yudao; Ji, Rong

doi:10.1016/j.envpol.2017.02.017

Cited by 30 publications

(11 citation statements)

References 59 publications

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“…The proposal is intensely discussed at the moment in consideration of further biodegradation data from RBTs (67.2% mineralization, Junker et al ) and simulation studies for sediment and soil (half‐lives <120 d) (ECHA ). As for aniline, NER formation (likely biogenic in the specific case of phenanthrene) has been found in simulation studies (Wang et al ), which may explain the mineralization below 50% observed in the SST.…”

Section: Resultsmentioning

confidence: 78%

Compartment‐Specific Screening Tools for Persistence: Potential Role and Application in the Regulatory Context

Junker

Coors

Schüürmann

2019

Integr Envir Assess & Manag

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The persistence assessment under the European Union regulation Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) relies on compartment‐specific degradation half‐lives derived from laboratory simulation studies with surface water, aquatic sediment, or soil. Although these data are given priority, they are not available for most of the compounds. Therefore, according to the Integrated Assessment and Testing Strategy (ITS) for persistence assessment, results from ready biodegradability tests (RBTs) are used within a persistence screening to decide whether a substance is considered as “not persistent” or “potentially persistent.” However, ready biodegradability is currently tested only in water. Consequently, there is a lack of approaches that include the soil and sediment compartments for persistence assessment at the screening level. In previous studies, compartment‐specific screening tools for water‐sediment (Water‐Sediment Screening Tool [WSST]) and soil (Soil Screening Tool [SST]) were developed based on the existing test guideline Organisation for Economic Development and Co‐operation (OECD TG 301C [MITI (Ministry of International Trade and Industry, Japan) test]). The test systems MITI, WSST, and SST were successfully applied to determine sound and reliable biodegradation data for 15 test compounds. In the present study, these results are used within the scope of a new alternative persistence screening approach, the Compartment‐Specific Persistence Screening (CSPS). Compared to the persistence screening under REACH, the CSPS is a more conservative approach that provides additional reasonable results, particularly for compounds that sorb to sediment and soil, and for which the current standard persistence screening might be insufficient. Thus, the CSPS can be used to identify potentially persistent and nonpersistent compounds in the regulatory context by a comprehensive assessment that includes water, soil, and sediment. Moreover, experimentally determined half‐lives from the compartment‐specific screening tools can be used as input for multimedia models that estimate, for example, overall persistence (Pov). The application of fixed half‐life factors to extrapolate from water to soil and sediment, which is here demonstrated to be inappropriate, can thereby be avoided. Integr Environ Assess Manag 2019;00:000–000. © 2019 SETAC

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Section: Resultsmentioning

confidence: 78%

Compartment‐Specific Screening Tools for Persistence: Potential Role and Application in the Regulatory Context

Junker

Coors

Schüürmann

2019

Integr Envir Assess & Manag

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“…The initial metabolites (step 1 NER-DDXs) and the more degraded DDXs (step 3 NER-DDXs) were mostly transported adsorbed on or entrapped in suspended solid particles/colloidal organic matter. Research on the transformation of phenanthrene into NER revealed that microbial activity is essential for the NER formation process with covalent bonds (Wang et al). An active microbial community was also believed to promote irreversible sorption of pesticides to soil. ,, This could explain the low proportion of covalently bound DDXs in groundwater sludge, where in general lower and divergent microbial effects occur than in surface water, − as a result of land filtration and the comparatively lower temperature.…”

Section: Results and Ddiscussionmentioning

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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“…These data can be used as endpoint for quantification of type I and type II NER. The experimental steps in the silylation procedure were described in detail, e.g., by [33] or in a slightly modified form [83].…”

Section: What Is Knownmentioning

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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Fate of phenanthrene and mineralization of its non-extractable residues in an oxic soil

Cited by 30 publications

References 59 publications

Compartment‐Specific Screening Tools for Persistence: Potential Role and Application in the Regulatory Context

Compartment‐Specific Screening Tools for Persistence: Potential Role and Application in the Regulatory Context

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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