Review Reports - Microplastics in the Rural Environment: Sources, Transport, and Impacts

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Although the topic—a review of sources, transport and impacts of microplastics in rural environments—is timely and potentially valuable, the manuscript’s overall quality is insufficient for publication. The narrative is poorly structured and the logic is confusing. There is substantial verbatim repetition (e.g., the sentence beginning “Sediments in lakes, rivers, and agricultural ditches serve as long-term repositories for microplastics…” appears multiple times around lines ~268, ~280, and ~341). These issues indicate inadequate synthesis and editing and warrant rejection in the current form.

Author Response

Reviewer 1:

Response: We sincerely thank the reviewer for their time and valuable comments on our manuscript. We acknowledge the concerns raised regarding the structure, logical flow, and repetition within the text. While we fully respect the reviewer’s assessment, we were hoping for more detailed and constructive feedback to help us identify the specific areas that require improvement. Such guidance would be greatly appreciated and would enable us to make substantial revisions to enhance the clarity, coherence, and overall quality of the manuscript. Thanks

Reviewer 2 Report

Comments and Suggestions for Authors

On line 34, the abbreviation “MPs” for microplastics has already been introduced earlier in the abstract, so here it would be better to just use the abbreviation instead of the full term to keep it concise and avoid repetition.
The section 2. on microplastic sources is very detailed, but it feels a bit like just a list of sources without enough connection between them. It would be helpful if you could add some synthesis or discussion that brings these different sources together — like how they might interact or which ones are more important overall. Maybe including a simple diagram or figure to show how these sources relate and affect microplastic pollution in rural areas would make it clearer. Also, mentioning any gaps or uncertainties in the data about these sources would give a more balanced view.
Sections 2.21 to 2.23 focus more on the composition and characteristics of microplastics rather than their sources. To improve the organization and clarity of the manuscript, I suggest moving these subsections into a new dedicated section focused on microplastic composition and physical properties.
It would be useful to briefly mention the factors influencing the transport mechanisms, such as particle size, shape, density, and weather/climatic conditions, since these strongly affect how microplastics move and settle
A short note on seasonal variability or extreme weather events (e.g., floods, droughts) influencing transport dynamics could add valuable context.
Figure 3 is a conceptual flow diagram, please ensure it clearly illustrates these key pathways and factors to complement the text effectively.
It would be valuable to briefly discuss how environmental degradation processes (e.g., UV exposure, mechanical wear, biodegradation) affect the polymer composition and structure of microplastics, potentially influencing their transport, persistence, and toxicity.
Consider emphasizing how soil types (e.g., sandy, clayey, organic-rich soils) influence microplastic accumulation and mobility, as these factors can significantly affect distribution patterns in rural compartments.
If possible, including additional insights into how microplastics affect reproductive success and growth in aquatic organisms would enrich the ecological impact discussion.
It may be useful to highlight the physical effects of microplastics on organisms’ feeding behavior and nutrient uptake (Section 4.6).
Given the emerging nature of Human Health Risiks, the authors might add a statement acknowledging current knowledge gaps and the need for further research to clarify the long-term health consequences of human exposure to microplastics, which would provide a balanced perspective.
In section 5, emphasize how different groups—like farmers, local authorities, and wastewater managers—can work together better.
Mention if things like financial rewards or fines could help encourage people to reduce plastic pollution.
Maybe include some new or promising ideas or technologies that can help rural communities manage microplastics.
Think about how to make sure these plans help everyone fairly, especially poorer or smaller communities.
Regarding the conclusion, it would benefit from emphasizing the urgent need for collaborative action among stakeholders and ongoing research to better understand health impacts, making it more accessible and actionable for policymakers and practitioners.
The authors should consider including a broader range of available studies and increase the number of references to strengthen the review, given that this is a comprehensive overview of the topic.

Author Response

Reviewer 2:

On line 34, the abbreviation “MPs” for microplastics has already been introduced earlier in the abstract, so here it would be better to just use the abbreviation instead of the full term to keep it concise and avoid repetition.

Response: Thank you. Yes, the abbreviation “MPs” for microplastics has already been introduced earlier in the abstract. But for the main section, such as introduction, we introduced it again, because abstract is a separate part of main section. It helps readers to follow it easily.

The section 2. on microplastic sources is very detailed, but it feels a bit like just a list of sources without enough connection between them. It would be helpful if you could add some synthesis or discussion that brings these different sources together — like how they might interact or which ones are more important overall. Maybe including a simple diagram or figure to show how these sources relate and affect microplastic pollution in rural areas would make it clearer. Also, mentioning any gaps or uncertainties in the data about these sources would give a more balanced view.

Response: Section 2 is updated based on reviewer 3 comments. Please see the updated version. Section 2 is fully revised and categorized in to 3 category such as

2.1 Rural specific sources,

2.2 Indirect sources,

2.3 General sources.

Thank you.

Sections 2.21 to 2.23 focus more on the composition and characteristics of microplastics rather than their sources. To improve the organization and clarity of the manuscript, I suggest moving these subsections into a new dedicated section focused on microplastic composition and physical properties.

Response: Please see the updated version. Thanks

It would be useful to briefly mention the factors influencing the transport mechanisms, such as particle size, shape, density, and weather/climatic conditions, since these strongly affect how microplastics move and settle.

Response: We have updated Section 3 to incorporate a brief discussion of particle-level characteristics (size, shape, density, polymer type) that influence microplastic transport behavior. The following paragraph was inserted after the introductory sentences of Section 3:

“The mobility of MPs is strongly modulated by intrinsic particle characteristics—including size, shape, density, and polymer type. Low-density polymers such as PE and PP are readily entrained in surface waters and remain buoyant for long periods, whereas denser polymers like PET and PS tend to associate with sediments or settle in low-energy zones [22, 48, 53]. Fibers, due to their high aspect ratio, often remain airborne for extended durations or become easily trapped in vegetation and biofilms, contributing to both aerial deposition and fluvial retention. Particle size also plays a decisive role: smaller particles (<100 µm) exhibit higher potential for percolation into soil pores and vadose zones [55], increasing both bioavailability and groundwater contamination risks.”

A short note on seasonal variability or extreme weather events (e.g., floods, droughts) influencing transport dynamics could add valuable context.

Response: We expanded Section 3 to address the role of seasonal hydrology, floods, and droughts in accelerating or modifying microplastic transport. The following paragraph was inserted after the rainfall/runoff discussion:

“Transport processes are highly season-dependent. Heavy monsoons, spring melt periods, and episodic flood events increase runoff velocities and sediment detachment, resulting in abrupt pulses of MP mobilization into receiving waters [12, 33]. Conversely, drought conditions promote surface accumulation of MPs and enhance wind-driven dispersal across agricultural fields and unpaved roads [39, 40]. Such hydrological extremes—intensified under climate-induced variability—contribute to irregular but ecologically significant redistribution events.”

Figure 3 is a conceptual flow diagram, please ensure it clearly illustrates these key pathways and factors to complement the text effectively.

Response: Thank you for this suggestion. Figure 3 has been fully revised to improve clarity and alignment with Section 3. The updated diagram now includes:

the major transport pathways (surface runoff, fluvial transport, groundwater infiltration, atmospheric deposition, soil vertical migration),
particle-level factors (size, shape, density, polymer type, weathering),
environmental and climatic factors (rainfall intensity, floods, droughts, wind, UV, soil texture), and
subsequent sinks, redistribution mechanisms, and exposure routes.

Figure is added in the manuscript.

Figure 3. Conceptual flow diagram of microplastics pathways in rural environments showing major sources, intrinsic particle factors (size, shape, density, polymer type, weathering), extrinsic environmental factors (rainfall intensity, floods, droughts, wind, UV exposure, soil texture), transport pathways (surface runoff, fluvial processes, groundwater infiltration, atmospheric deposition, soil vertical migration), environmental sinks, redistribution mechanisms, and exposure routes.

It would be valuable to briefly discuss how environmental degradation processes (e.g., UV exposure, mechanical wear, biodegradation) affect the polymer composition and structure of microplastics, potentially influencing their transport, persistence, and toxicity.

Response: We added a paragraph describing how environmental weathering modifies particle behavior and fate. This paragraph was inserted after the atmospheric transport section:

“As particles traverse between environmental compartments, they undergo continuous weathering through UV radiation, mechanical abrasion, freeze–thaw cycles, and microbial activity [21]. These processes fragment larger plastics into smaller size classes, alter surface chemistry, increase roughness, and may change density, thereby modifying transport behavior and sorption capacity for co-occurring pollutants. Such degradation enhances mobility in some cases—e.g., producing smaller particles that infiltrate soils more readily—while also increasing ecological risk due to greater bioavailability.”

Consider emphasizing how soil types (e.g., sandy, clayey, organic-rich soils) influence microplastic accumulation and mobility, as these factors can significantly affect distribution patterns in rural compartments. If possible, including additional insights into how microplastics affect reproductive success and growth in aquatic organisms would enrich the ecological impact discussion.

Response: Inserted after the groundwater infiltration paragraph:

“Soil texture and structure strongly affect vertical and lateral MP transport. Sandy, highly permeable soils accelerate downward migration through larger pore spaces, whereas clay-rich or compacted soils retain MPs in upper horizons by limiting hydraulic conductivity [36]. Organic-rich soils can promote aggregation of MPs with humic substances, resulting in localized retention, though bioturbation may later redistribute these particles [49]. Such heterogeneity complicates predictions of subsurface transport and underscores the need for soil-specific assessments in rural landscapes.”

Inserted at the end of Section 3:

“These interconnected transport pathways also shape exposure profiles for rural biota. MPs redistributed into headwater streams, ponds, or agricultural drainage systems become accessible to macro-invertebrates, larvae, and small fish, potentially impairing growth, feeding efficiency, and reproductive success [63, 64, 66]. In soils, transported MPs interact with microbial communities, plant roots, and soil fauna—affecting nutrient dynamics, enzyme activity, and plant performance [23, 68]. Thus, understanding transport dynamics is essential not only for predicting spatial contamination patterns but also for evaluating ecological impacts across multiple trophic levels.”

It may be useful to highlight the physical effects of microplastics on organisms’ feeding behavior and nutrient uptake (Section 4.6).

Response: Please see the updated version:

The potential for bioaccumulation of microplastics and associated pollutants across trophic levels is a growing concern in rural food webs. Microplastics ingested by invertebrates or small fish can be transferred to larger predators—including humans—through dietary exposure [70]. Keisling et al. [5] reported microplastics presence in oysters from a rural estuary in Georgia, USA, albeit at lower concentrations than urban analogs. The presence of MPs in consumable species raises questions about food safety in aquaculture and small-scale rural fisheries. Microplastics can also physically interfere with organisms’ feeding behavior and nutrient uptake, potentially reducing growth and overall fitness. Although acute toxicity from microplastics alone is rare, their role as vectors for persistent organic pollutants and pathogens increases ecological risk.

Thank you.

Given the emerging nature of Human Health Risiks, the authors might add a statement acknowledging current knowledge gaps and the need for further research to clarify the long-term health consequences of human exposure to microplastics, which would provide a balanced perspective.

Response: Please see the following:

To address existing gaps, future work should prioritize:

Standardized rural microplastics monitoring protocols for air, water, soil, and food.
Contextualized mitigation strategies targeting biosolids use, mulching films, and decentralized sanitation.
Investment in rural infrastructure, including plastic waste collection and wastewater upgrades.
Integration of rural microplastics data into national plastic reduction policies.
Research to address knowledge gaps on the long-term human health impacts of microplastics exposure.

In section 5, emphasize how different groups—like farmers, local authorities, and wastewater managers—can work together better. Mention if things like financial rewards or fines could help encourage people to reduce plastic pollution. Maybe include some new or promising ideas or technologies that can help rural communities manage microplastics. Think about how to make sure these plans help everyone fairly, especially poorer or smaller communities.

Response: Following paragraph is added at the end of section 5. Thanks.

Finally, reducing microplastic pollution in rural environments requires strong coordination among farmers, local authorities, and waste management agencies. Efforts should focus on reducing the use of plastic products, raising awareness by engaging rural communities, promoting safe waste disposal practices, and encouraging farmers to adopt modern and sustainable agricultural techniques. New and affordable technologies, such as natural material filters, plant-based treatment systems, and biodegradable farm plastics, can further support these efforts. Introducing financial rewards for good waste management practices and applying fines for illegal dumping or open burning could also motivate people to act responsibly. It is also important to ensure that these plans benefit all groups fairly, especially poorer or smaller communities that may have limited resources or access to technology. Regular and open communication among these groups will make their work more effective and help move rural areas toward a cleaner, safer, and more sustainable environment.

Regarding the conclusion, it would benefit from emphasizing the urgent need for collaborative action among stakeholders and ongoing research to better understand health impacts, making it more accessible and actionable for policymakers and practitioners.

Response: Please see the updated conclusion:

Conclusion:

This study demonstrates that microplastics are prevalent in rural environments, contrary to the assumption that such areas are relatively uncontaminated. The highest concentrations were observed in soils and freshwater systems, reflecting the influence of agricultural runoff, wastewater, and atmospheric deposition. The most common polymers detected were polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET), typically occurring as fibers, fragments, and films. These microplastics persist in the environment and can accumulate in soil and water, potentially entering local food chains and affecting product quality. The findings highlight that rural systems are significant reservoirs of microplastics, with implications for ecological health, soil fertility, and food safety. Also, addressing microplastics in rural environments requires urgent collaboration among researchers, policymakers, and local stakeholders, alongside continued research to clarify long-term human health impacts and guide effective interventions.

The authors should consider including a broader range of available studies and increase the number of references to strengthen the review, given that this is a comprehensive overview of the topic.

Response: Few more related studies were added. Thank you.

Reviewer 3 Report

Comments and Suggestions for Authors

The work presented by the authors addresses the important and urgent problem of environmental pollution with microplastics.

The first sentence of the abstract is, in this form, removed from the entire work. In my opinion, it should be restructured and explain the issue of microplastics and their sources, etc., after sentence 1.

The journal's guidelines call for a maximum of five keywords.

The introduction lacks information about the discovery of microplastics in pristine areas where they were previously thought to be impenetrable, and in the ocean depths. Additionally, it would be valuable to highlight the problems associated with microplastics not only in animals but also in the human body. Furthermore, geologists have discovered the penetration of microplastics into rock layers and the permanent bonding of synthetic polymers with the minerals that comprise them. I would suggest that the authors emphasize the importance of rural areas for population health and the problem of microplastic pollution (the authors present this issue in a disorganized manner – it appears in several places in the introduction).

431 / 5 000 In Chapter 2, I proposed to separate the sources of plastic typical for rural areas, such as fertilizer coatings and plant protection products, indirect sources (occurring in rural and urban areas, e.g. improperly stored waste), and "general" - non-specific sources, i.e. originating from the abrasion of tires, clothing, etc. This would make it possible to define in the future the most frequent sources of microplastic pollution in a given region. Figures 1 and 3 were not discussed in the text. Please analyze and reformulate the conclusions to provide a brief summary of the work conducted. This section should not include summaries of previous chapters or suggestions for future work. Authors should focus on identifying where most microplastics are found in rural areas, what type of polymer it is, how it affects products, etc.

I believe that, despite its shortcomings, the work is important and contributes to increasing knowledge about environmental pollution caused by synthetic polymers. The work is interesting and worth publishing after revisions.

Author Response

Reviewer 3:

The first sentence of the abstract is, in this form, removed from the entire work. In my opinion, it should be restructured and explain the issue of microplastics and their sources, etc., after sentence 1.

Response: Please see the updated abstract.

The journal's guidelines call for a maximum of five keywords.

Responses: We have updated keywords. Please see:

Keywords: microplastics; rural environment; freshwater pollution; atmospheric deposition; agricultural runoff;

The introduction lacks information about the discovery of microplastics in pristine areas where they were previously thought to be impenetrable, and in the ocean depths. Additionally, it would be valuable to highlight the problems associated with microplastics not only in animals but also in the human body. Furthermore, geologists have discovered the penetration of microplastics into rock layers and the permanent bonding of synthetic polymers with the minerals that comprise them. I would suggest that the authors emphasize the importance of rural areas for population health and the problem of microplastic pollution (the authors present this issue in a disorganized manner – it appears in several places in the introduction).

Responses: Thank you very much. We have checked our introduction again. We found,

Paragraph 1: global background and problem statement

Paragraph 2: rationale for rural focus

Paragraphs 3–4: empirical evidence in rural contexts

Paragraph 5: aims and contribution

We have now added a new paragraph between Paragraphs 3–4 and Paragraph 5 in the introduction section and it highlights all your concern.

Recent studies have shown that microplastics are now being found in environments where they were once thought not to be present. In particular, microplastics have been detected in Arctic snow, remote mountain peaks, and the deep-sea floor, raising concerns among researchers and environmentalists. Moreover, microplastics have been discovered in human lungs, blood, tissues, and various other parts of the body, posing potential health risks and prompting concern among medical professionals. Geologists have also identified microplastics embedded in sediment layers and bound to mineral matrices, highlighting their long-term persistence in the environment.

Thanks

In Chapter 2, I proposed to separate the sources of plastic typical for rural areas, such as fertilizer coatings and plant protection products, indirect sources (occurring in rural and urban areas, e.g. improperly stored waste), and "general" - non-specific sources, i.e. originating from the abrasion of tires, clothing, etc. This would make it possible to define in the future the most frequent sources of microplastic pollution in a given region.

Response: Section 2 is fully revised and categorized in to 3 category such as

2.1 Rural specific sources,

2.2 Indirect sources,

2.3 General sources.

Thank you for your valuable feedback.

Figures 1 and 3 were not discussed in the text.

Responses: Figure 1 is described in sub section 2.21 and Figure 3 is described in Section 3. Please see the highlighted part. Thanks

Please analyze and reformulate the conclusions to provide a brief summary of the work conducted. This section should not include summaries of previous chapters or suggestions for future work. Authors should focus on identifying where most microplastics are found in rural areas, what type of polymer it is, how it affects products, etc.

Response: Please see the updated conclusion:

Conclusion:

I believe that, despite its shortcomings, the work is important and contributes to increasing knowledge about environmental pollution caused by synthetic polymers. The work is interesting and worth publishing after revisions.

Response: Thank you very much.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Agree for publication.

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have thoroughly revised the manuscript following the reviewers’ recommendations. The improved version is now suitable for acceptance and publication in Pollutants.