Microplastics and Nanoplastics Monitoring in Climate-Shock andExtreme-Weather Events: Retrospective Analysis and aProposed Framework for Prediction Using Field-Deployable Tools

Abstract Climate-driven extreme events, floods, cyclones, typhoons, and heavy rainfall, rapidly alter water quality through infrastructure damage, sediment resuspension, runoff, and mobilization of plastic debris. Published studies document several-fold to order-of-magnitude changes in environmental microplastic (MP) concentrations during or after these events. Conventional laboratory methods limit the frequency and geographic density of measurements.

These observations, together with documented associations between MP transport and rainfall, runoff, and hydrological conditions, support a research question: whether high-frequency MP/NP measurements can contribute incremental information to multi-parameter models that already incorporate meteorological, hydrological, satellite, and geospatial variables. Predictive utility has not been established and requires prospective validation. The ability to collect repeated measurements at higher temporal resolution may nevertheless open new opportunities to study microplastics both as contaminants mobilized by climate shocks and as environmental variables within climate-resilience research.    EcoExposure™ is a smartphone-enabled optical platform designed for rapid, field-deployable assessment of MPs/nanoplastics (NPs) and complementary water-quality indicators, which is proposed to be employed along with other tools to collect real-time data for both post-event analysis and future predictions of extreme weather events.

Figure 1. Proposed high-frequency field monitoring across the climate-disaster cycle. Repeated MP/NP and complementary water-quality measurements could establish pre-season baselines and characterize changes before, during, and after extreme hydrological events. Integration with contemporaneous meteorological and hydrological data could support prospective research, while post-event departures from baseline could provide more immediate applications for WASH impact assessment, response prioritization, recovery monitoring, and resilience evaluation.

1. Background and RationaleExtreme hydrological events can rapidly degrade water quality. Flooding, cyclones, and heavy rainfall mobilize sediments, microorganisms, nutrients, chemicals, and plastics into surface and drinking-water sources. These effects are especially consequential where laboratory capacity is limited or infrastructure has been damaged.

A growing literature shows that extreme events substantially alter environmental MP abundance.

Documented changes include:

• substantial increases after catastrophic flooding in the Three Gorges Reservoir;

• approximately three-fold increases after major floods in Indian river–estuarine systems;

• several-fold increases in coastal seawater after typhoons and higher wet-season abundance;

• increases of one to four orders of magnitude during high-flow versus baseflow conditions in some rivers;

• approximately fourteen-fold increases after flooding in Mersin Bay; and

• export of roughly 70 % of previously stored river-bed microplastics during a major UK catchment flood.

Turbidity, suspended solids, microbial indicators, and other contaminants often change concurrently. The water-quality consequences of climate shocks are therefore multivariate.

Most existing MP studies rely on sparse sampling because conventional analysis requires transport, specialized instrumentation, and trained personnel. As a result, the literature is dominated by pre-/post-event comparisons or retrospective sediment records.

Continuous characterization across the full sequence—baseline → onset → peak → recession → recovery—remains rare.

A rapid field-deployable system could make higher temporal resolution practical.

2. Preliminary Retrospective EvidenceSediment cores provide an independent record of whether extreme events leave measurable MP signals. Recent work has examined microplastics as potential retrospective markers of floods and hurricanes.  Published data from two Puerto Rico coastal sediment cores were examined. Hurricane-associated intervals had been independently identified by the original investigators using chronological, sedimentary, geochemical, and tropical-cyclone evidence.

Table 1. Exploratory comparison of microplastic concentrations in hurricane-associated versus background sediment layers

Core	Hurricane-associated concentrations (MP/kg)	Mean hurricane-associated (MP/kg)	Estimated mean background (MP/kg)*	Approximate ratio	Published p-value
Guayama (GUY 2)	236, 295, 250	260	~50	~5.2×	0.0071
Levittown (LEV 4)	171, 331, 453	318	~80	~4.0×	0.015

*Background means are exploratory estimates derived from published whole-core averages and the number of event versus non-event intervals; they were not reported as background means by the original authors.

Figure 2. Retrospective microplastic signals associated with extreme-weather events. Exploratory analysis of published Puerto Rico sediment-core data showed approximately 5.2-fold and 4.0-fold higher mean MP concentrations in hurricane-associated versus estimated background layers in the Guayama (GUY 2) and Levittown (LEV 4) cores, respectively. Hurricane-associated intervals were independently identified by the original investigators using chronological, sedimentary, geochemical, and tropical-cyclone evidence. Background concentrations shown are

Across both cores, hurricane-associated layers contained approximately four- to five-fold higher mean MP concentrations than estimated background layers. These intervals correspond to independently documented storms (including Hurricane Georges and Hurricane María). The relationship therefore does not arise from circular definition of event layers by MP concentration alone.

These data do not demonstrate that microplastics predict hurricanes. They do show that extreme hydrological events can leave quantitatively distinguishable MP signals in environmental records, providing a rationale for investigating higher-frequency contemporary measurements.

3. From Retrospective Signals to Prospective Monitoring

The literature can be viewed along a continuum:  Historical extreme-event signal (sediment cores) → Contemporary event response (surface-water, stormwater, and atmospheric studies) → High-frequency prospective measurement (field-deployable optical tools) → Multi-parameter modeling (MP/NP features evaluated alongside meteorological, hydrological, and geospatial variables)

The scientific question is not whether MPs should replace established predictors, but whether they provide incremental information beyond those predictors.

4. Proposed Multi-Parameter Research FrameworkA prospective study could test this directly by generating high-frequency MP/NP and turbidity time series at fixed sites and pairing each measurement with:

• precipitation and antecedent rainfall

• rainfall intensity

• relative humidity and atmospheric pressure

• wind speed and direction

• PM2.5 / PM10

• soil moisture

• river stage and streamflow

• satellite precipitation and soil-moisture products

• land-use, elevation, and upstream urbanization metrics

Both absolute concentrations and temporal derivatives (rate and direction of change) could be evaluated. Possible behaviors include accumulation before precipitation, first-flush spikes, dilution, sediment resuspension, or delayed mobilization. Increases, decreases, thresholds, and interactions with conventional variables are all of interest.

Figure 3. Proposed multi-parameter framework for investigating extreme-event prediction. High-frequency MP/NP and water-quality measurements could be integrated with established meteorological, atmospheric, hydrological, satellite, and geospatial variables. The proposed research question is whether MP/NP-derived features—including absolute concentrations and temporal changes—provide incremental predictive information beyond conventional environmental predictors. Predictive utility of MPs/NPs has not yet been established and would require prospective validation across multiple events and watersheds.

4.1 Baseline Model

A baseline model might incorporate established variables:

The primary outcome is clear: Does inclusion of MP/NP-derived features improve out-of-sample predictive performance relative to meteorological, hydrological, and geospatial variables alone?

Prospective validation across multiple events and watersheds would be required before any operational claims.

4.2. Post-Event Impact Assessment

The most immediately supported climate application is rapid assessment following an extreme event.

Following flooding, cyclones, typhoons, or severe rainfall, the same sites used to establish baseline conditions could be reassessed.

Changes could be expressed simply as:

Analogous measures could be calculated for NP and turbidity indicators.  Spatial mapping could then identify locations exhibiting the largest departures from baseline.

Such information could potentially assist WASH and disaster-response organizations in:

1. identifying water sources experiencing substantial contamination changes;

2. prioritizing confirmatory testing;

3. directing treatment or alternative-water interventions;

4. documenting geographical patterns of runoff and contaminant transport; and

5. monitoring whether water quality returns toward baseline during recovery.

Repeated measurements could therefore provide information beyond a binary designation of a water source as affected or unaffected.

5. Relevance to WASH and Climate Resilience

Immediate value does not depend on predictive capability. Field-deployable monitoring can support:

• Preparedness – pre-season baselines and identification of vulnerable sources

• Event monitoring – characterization of rapidly changing conditions

• Response – prioritization of confirmatory testing and interventions

• Recovery – tracking return toward baseline

• Resilience assessment – comparison of contamination responses before and after infrastructure or watershed interventions

These functions complement existing disaster-management, hydrological, and humanitarian WASH systems.

Figure 1. Proposed high-frequency field monitoring across the climate-disaster cycle. Repeated MP/NP and complementary water-quality measurements could establish pre-season baselines and characterize changes before, during, and after extreme hydrological events. Integration with contemporaneous meteorological and hydrological data could support prospective research, while post-event departures from baseline could provide more immediate applications for WASH impact assessment, response prioritization, recovery monitoring, and resilience evaluation.

6. EcoExposure™ Platform EcoExposure™ is an AI  smartphone-enabled optical platform that evaluates particulate and polymer-associated signals in intact liquid samples. Core elements include adaptive optical reference metrics, controlled reagent kinetics, physics-informed image analysis with computer vision, and field-oriented workflows designed for non-specialist operation. Where has water quality changed, by how much, and where should limited resources or confirmatory testing be directed?

·       Applications Across the Climate-Disaster Cycle Seasonal / pre-disaster baseline:– repeated measurements at rivers, reservoirs, community water points, and other priority sources to characterize normal variability.

·       High-frequency monitoring during storm seasons: denser sampling as severe weather approaches, temporally linked to meteorological and hydrological variables.

·       Post-event impact assessment: rapid re-measurement of the same sites to quantify departures from baseline and prioritize response.

·       Recovery tracking” continued sampling to determine whether indicators return toward pre-event levels.

8. Discussion and LimitationsExisting evidence establishes that extreme hydrological events can substantially alter environmental MP concentrations and that some events leave persistent sedimentary signals. The principal limitation of the current evidence base is sampling density rather than analytical sensitivity alone.

A field-deployable platform changes the questions that can be asked by enabling repeated measurements across entire storm seasons. The approximately four- to five-fold difference observed in the Puerto Rico cores illustrates the potential magnitude of extreme-event-associated signals, but retrospective association does not establish prospective predictive utility.

Three claims must remain distinct:

1. Extreme weather alters environmental MP concentrations.

2. MP abundance in sediment records can provide retrospective information about historical extreme events.

3. Whether high-frequency contemporary MP/NP measurements provide incremental predictive information remains unknown and requires prospective testing.

EcoExposure requires further validation across diverse matrices, polymer compositions, concentrations, and climates. The Puerto Rico comparison is exploratory, based on two cores, and should not be generalized. Environmental MP concentrations are influenced by many confounders; future studies must control for these factors and evaluate performance across independent events.

9. ConclusionClimate-driven extreme events can substantially redistribute microplastics and other contaminants. A preliminary examination of published Puerto Rico sediment-core data shows that hurricane-associated layers contained approximately four- to five-fold higher mean MP concentrations than estimated background layers.

These observations support immediate applications in baseline establishment, impact assessment, and recovery monitoring. They also motivate a broader research opportunity: the generation of high-frequency longitudinal datasets that can test whether MP/NP signals contribute incremental information when combined with established meteorological, hydrological, satellite, and geospatial variables.

Field-deployable optical tools make such datasets newly practical and may therefore advance both operational climate-resilient WASH monitoring and fundamental understanding of microplastic dynamics under extreme hydrological conditions.

Representative References

1.     Xia Y, et al. Impact of flooding on microplastic abundance and distribution in freshwater environment: a review. Environ Sci Pollut Res. 2023. doi:10.1007/s11356-023-30819-8

2.     Xu D, Gao B, Wan X, Peng W, Zhang B. Influence of catastrophic flood on microplastics organization in surface water of the Three Gorges Reservoir, China. Water Res. 2022.

3.     Recent Tuticorin / Thamirabarani flood study (2025). Post-flood samples had thrice more microplastic abundance than pre-flood samples in water (mean 28.3 → 95.1 items/L). Mar Pollut Bull.

4.     Studies of the 2018 Kerala floods. Approximately 3-fold increase in surface-water microplastics post-flood. Multiple reports, 2022–2023.

5.     Cheung et al. and related Hong Kong coastal studies. Typhoons and rainstorms induced 3.5–6.0× (seawater) and up to 36× (sediment) increases; wet-season abundance ~5× dry-season baseline.

6.     Tanaka M, et al. (and related Japanese river high-flow studies). Microplastic and mesoplastic mass concentrations increased 1–4 orders of magnitude during high-flow events relative to low-flow conditions. Water Res. 2026.

7.     Gündoğdu S, et al. How microplastics quantities increase with flood events? An example from Mersin Bay. Environ Pollut. 2018;239:342-350. (≈14-fold increase).

8.     Hurley R, Woodward J, Rothwell JJ. Microplastic contamination of river beds significantly reduced by catchment-wide flooding. Nat Geosci. 2018;11:251-257.

Analyses of precipitation and flood effects on drinking-water quality indicators (coliforms, E. coli, turbidity, disinfectant by-products). Multiple systems show elevated microbial detection risk (14–26%) and turbidity aft