the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 02 Sep 2026
The impacts of remediation techniques on soil functions: a review
Abstract. Soil contamination is a major driver of soil degradation in Europe, and remediation practices are increasingly expected to support not only risk reduction but also the recovery of soil health and ecosystem services. In line with the European Soil Monitoring and Resilience Directive, this review evaluates how commonly applied remediation techniques impact key soil functions that underpin soil health. A structured narrative review of the literature was conducted to assess the impacts of conventional (physical and chemical) and low‑impact (biological and nature‑based) remediation techniques on six aggregated soil functions: organic matter storage and transformation, water regulation, nutrient cycling, contaminant retention and degradation, physical stability, and habitat provision. The analysis shows that conventional remediation techniques such as thermal treatment, soil washing, in‑situ chemical oxidation/reduction, and stabilization/solidification frequently achieve effective contaminant removal but often cause substantial and sometimes irreversible degradation of soil structure, organic matter, microbial activity, and habitat quality. In contrast, low‑impact remediation approaches, including bioremediation, phytoremediation, monitored natural attenuation, and immobilization with organic or selected inorganic amendments tend to preserve or enhance soil functions, although typically at slower contaminant removal rates and with strong site specificity. The review highlights critical knowledge gaps, particularly regarding limited information on specific remediation techniques and impacts on soil fauna, the limited availability of quantitative thresholds for when a soil can be considered healthy or unhealthy for performing various functions, and limited soil health assessments in urban and industrial context. Hybrid and adaptive remediation strategies that combine risk reduction with rehabilitation measures are identified as key to balancing risk reduction and soil functionality while also planning for refunctionalization at the onset as part of the soil health trajectory. Overall, embedding soil health as a central management objective is essential for sustainable contaminated land management aligned with European policy goals.
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RC1: 'Comment on egusphere-2026-4977', Anonymous Referee #1, 09 Sep 2026
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AC1: 'Reply on RC1', Paul Drenning, 12 Oct 2026
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We thank the reviewer for the encouragement and constructive criticism of the manuscript. The reviewer’s comments point out several areas where the manuscript can be made clearer, more transparent, and more understandable. Following the open discussion phase, we will provide a more formal point-by-point response to all the reviewer’s criticisms. For now, we will address these main criticisms briefly below to promote discussion, focusing on the review methodology, adding a quantitative assessment, incorporating additional aspects like contaminant reduction effectiveness, and terminology and readability.
Methodology. The current methodology identifies the database, broad search logic, screening process, inclusion criterion, number of shortlisted articles, and the absence of a lower publication-year restriction. However, the reviewer is right to point out that some important decisions remain insufficiently transparent. We agree that the methodology requires further detail and will clarify according to the reviewer’s comments in the revised manuscript, including better explaining the scoring process. We will also clarify how the aggregated scores for each soil function were derived and report the number of contributing studies, where feasible, so that readers can better distinguish comparatively well-supported patterns from areas where evidence remains limited. This has already been partially addressed in the manuscript but can be better clarified.
The resulting score is broadly supported by the description of each technology in the Results section, which was expansive by design and structured to group conclusions for the specific soil functions, to support the conclusions drawn and give a sufficiently comprehensive overview of the literature basis. However, the reviewer is right to point out that this could be better streamlined. Also, our scoring approach could be further discussed. For this study, we decided that a simplified scoring system was most suitable to indicate the general trend and indicate gradations of consensus and uncertainty, and that many different technologies were evaluated. In many cases, the results are mixed and depend strongly on site-specific factors that are difficult to disaggregate. We believe that this qualitative assessment still provides valuable information and can be used to identify areas where further research is needed. However, we acknowledge in the manuscript that outcomes are site- and treatment-dependent and that its results should be interpreted as broad trends rather than predictive estimates.
This provides the context for discussing the reviewer’s main feedback regarding the inclusion of a more quantitative assessment.
Quantitative assessment. The reviewer raises an important point concerning quantitative estimation of treatment effects on both reduction in contaminant concentrations and impacts on soil functions. Such a quantitative analysis would indeed increase analytical strength of the paper, and we generally agree that there is a need for this research. However, it is not a small revision and is beyond the scope of work for this . The manuscript is explicitly framed as a structured narrative review, and the evidence covers highly heterogeneous technologies, indicators, contaminants, soil types, experimental designs, treatment intensities, time points, and controls. Few reviews assessing remediation impacts on soil functions have been conducted (e.g., Volchko et al., 2013; O’Brien et al., 2017), so we decided that it would be most appropriate to position this study as a scoping analysis that broadly assesses the current state of knowledge while showing some directions for future research instead of investigating a few at depth. We state in the manuscript that further quantitative synthesis and meta-analysis are a future research need, and there is a lack of data for many technologies and soil functions. We will consider, though, how a more quantitative indication can be added.
Contaminant reduction. The reviewer further recommends incorporating the reduction in contaminant concentrations into the comparison in this paper. While we generally agree with this premise, that analysis is not the specific aim of this paper. Indeed, the original inclusion criteria focused on studies reporting changes in soil-function-related indicators and studies reporting only remediation efficiency, which make up the majority of the literature, were deliberately not included since there are many such reviews already. However, this may be viewed as an oversight. We will consider adding in the revised manuscript that this review that specifically focuses on soil functions may be most informative when viewed side-by-side with other reviews targeted towards contaminant/risk reduction, e.g., Kuppusamy et al. (2016; 2017), Hou et al. (2023); Liu et al. (2018); Lim et al. (2016).
Also, we would like to point out that the soil function “contaminants retention, transformation and degradation” was focused here on the specific impacts of remediation techniques on “soil’s inherent capacity to retain, transform and degrade contaminants and manage residual contaminants”. We believe that this is an important distinction and one that is often overlooked when considering risk mitigation since a healthy soil has a higher capacity for this function. For example, this can refer to the soil’s continued capacity to manage residual contaminants and mitigate ecotoxicity. Also, the potential negative consequence of leaching from the impacted soil matrix could be a significant concern. We invite further discussion on this point from the reviewer and other experts.
Terminology and readability. The reviewer is right to point out that some terminology should be applied more consistently. We will review the use of terms such as soil properties, descriptors, indicators, proxy indicators, functions, and health, and define their relationships more explicitly.
The reviewer commented on the sharp distinction between “conventional” and “low-input/low-impact” remediation. This choice was made based on internal discussions and following a recent publication of low-impact remediation techniques (LIRT) by Bardos et al. (2026). There is indeed significant overlap between LIRT and gentle remediation options (GRO). We will discuss further whether to change this category or clarify the distinction. We invite further comments and discussion on this point.
References:
Bardos, P., Lai, J., Pizzol, L., Sellitri, A., Couto, N., Derycke, V., Guyonnet, D., Vogel, T. M., Kumpiene, J., & Cundy, A. (2026). Low input remediation techniques for contaminated site management. Environmental Science: Advances. https://doi.org/10.1039/D5VA00242GHou, D., Al-Tabbaa, A., O’Connor, D., Hu, Q., Zhu, Y.-G., Wang, L., Kirkwood, N., Ok, Y. S., Tsang, D. C. W., Bolan, N. S., & Rinklebe, J. (2023). Sustainable remediation and redevelopment of brownfield sites. Nature Reviews Earth & Environment, 4(4), 271–286. https://doi.org/10.1038/s43017-023-00404-1Kuppusamy, S., Palanisami, T., Megharaj, M., Venkateswarlu, K., & Naidu, R. (2016). In-Situ Remediation Approaches for the Management of Contaminated Sites: A Comprehensive Overview. In P. de Voogt (Ed.), Reviews of Environmental Contamination and Toxicology Volume 236 (pp. 1–115). Springer International Publishing. https://doi.org/10.1007/978-3-319-20013-2_1Kuppusamy, S., Thavamani, P., Venkateswarlu, K., Lee, Y. B., Naidu, R., & Megharaj, M. (2017). Remediation approaches for polycyclic aromatic hydrocarbons (PAHs) contaminated soils: Technological constraints, emerging trends and future directions. Chemosphere, 168, 944–968. https://doi.org/10.1016/j.chemosphere.2016.10.115Lim, M. W., Lau, E. V., & Poh, P. E. (2016). A comprehensive guide of remediation technologies for oil contaminated soil—Present works and future directions. Marine Pollution Bulletin, 109(1), 14–45. https://doi.org/10.1016/j.marpolbul.2016.04.023Liu, L., Li, W., Song, W., & Guo, M. (2018). Remediation techniques for heavy metal-contaminated soils: Principles and applicability. Science of The Total Environment, 633, 206–219. https://doi.org/10.1016/j.scitotenv.2018.03.161O’Brien, P. L., DeSutter, T. M., Casey, F. X. M., Wick, A. F., & Khan, E. (2017). Evaluation of Soil Function Following Remediation of Petroleum Hydrocarbons—A Review of Current Remediation Techniques. Current Pollution Reports, 3(3), 192–205. https://doi.org/10.1007/s40726-017-0063-7Volchko, Y., Norrman, J., Bergknut, M., Rosén, L., & Söderqvist, T. (2013). Incorporating the soil function concept into sustainability appraisal of remediation alternatives. Journal of Environmental Management, 129. https://doi.org/10.1016/j.jenvman.2013.07.025Citation: https://doi.org/10.5194/egusphere-2026-4977-AC1
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AC1: 'Reply on RC1', Paul Drenning, 12 Oct 2026
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- 1
This is a very interesting, relevant and timely review addressing the impacts of different soil remediation technologies on soil functioning and health. The topic is highly relevant, and the manuscript has the potential to make a valuable contribution. However, I believe that the text still needs some polishing. In particular, some sentences are overly long and could be reformulated to improve readability and facilitate understanding. I also recommend ensuring greater consistency in the terminology and concepts used throughout the manuscript (or clearly distinguishing between concepts where they are not equivalent).
I also think that the methodology used to conduct the review should be described in greater detail. In my opinion, the manuscript would benefit substantially from a more quantitative approach. Apart from that, I would recommend incorporating the reduction in contaminant concentrations into the comparison. Since the manuscript argues that remediation technologies should aim to achieve both risk reduction through contaminant removal and the maintenance or improvement of soil health and functioning, these two dimensions should ideally be evaluated together.
The Results section is currently very long, with an extensive description of each technology and its individual impacts. I believe the manuscript would benefit from synthesising this information more effectively and focusing on the main patterns emerging across technologies. Finally, it is positive that the manuscript concludes by identifying knowledge gaps and discussing soil refunctionalisation and the need to balance risk reduction with the preservation or recovery of soil functionality.
Specific comments:
Please reconsider the terminology used to distinguish the two main types of remediation technologies. The manuscript currently distinguishes between conventional technologies (physical and chemical) and low-impact technologies (biological and nature-based). However, amendments are included in the latter category despite being chemical interventions. What terminology is currently most widely used in the literature? Gentle remediation options (GROs) could potentially be considered as an alternative term for the second group.
L30: Why not use “land use” instead of “context”?
L42: I believe “unhealthy” is more appropriate than “healthy” in this sentence. Please check and correct.
L45 and throughout: Please ensure consistency in the terminology used for the different concepts. The manuscript refers to soil quality indicators, soil descriptors, indicators, proxy indicators, etc. These terms should either be used consistently or their differences should be clearly defined.
Some sentences are overly long and would benefit from being reformulated to improve readability (e.g., L57-61 and L108-130).
L107: Please use “SML” instead of “Soil Directive”.
L114: Please spell out the abbreviation at its first occurrence and use the abbreviation thereafter (e.g., SOC).
L126: “Effects on macrofauna (earthworms)”: Does this refer specifically to earthworm abundance? Please clarify.
Similarly, the parameters included in Tables S2 and S3 should be described more clearly. For example, it is unclear what methodology or measurement is represented by “Functional diversity/genes” or what MSIR refers to. There is also a question mark in Table S3 whose meaning is unclear and should be checked.
L136: How do you determine whether a study is representative if the review is simultaneously described as non-exhaustive? Please clarify the criteria used.
L145: Please specify the starting year of the literature search.
Table 1: The manuscript does not explain how it was determined which category a given result belongs to.
As mentioned above, I believe the robustness and impact of the manuscript would be substantially enhanced by performing a quantitative estimation of the effects of each remediation treatment on soil functions, ideally by comparing the response with the control treatment within each individual study. This would provide a more objective assessment of the magnitude and direction of the effects across remediation technologies.
Table 2: It would be useful to report the number of studies considered for each soil function and remediation technology. It is also unclear how the mean value reported for each soil function was calculated.
As mentioned above, it would also be highly valuable to include the mean reduction in contaminant concentrations achieved by each technology.
Figure 1: I believe it is important that pollutants are not transferred to the final products of biofuel production. See, for example, Tripathi et al. (2016), https://doi.org/10.1016/j.rser.2015.12.116. Please revise the figure accordingly.