
==== Front
Heliyon
Heliyon
Heliyon
2405-8440
Elsevier

S2405-8440(24)12533-9
10.1016/j.heliyon.2024.e36502
e36502
Research Article
Migration and accumulation patterns of plastic waste in the environment: A comprehensive simulation study
Al Khoeriyah Zayinatun Biladiyah
Sembiring Emenda emenda@itb.ac.id
⁎
Environmental Engineering Study Program, Faculty of Civil and Environmental Engineering, Institut Teknologi Bandung, Indonesia
⁎ Corresponding author. emenda@itb.ac.id
18 8 2024
30 8 2024
18 8 2024
10 16 e365029 2 2024
16 8 2024
16 8 2024
© 2024 The Authors
2024
https://creativecommons.org/licenses/by-nc/4.0/ This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/).
Plastic waste is commonly littered in the environment due to insufficient waste management practices. Mismanaged plastic waste may migrate and accumulate in terrestrial and aquatic environments. Plastic waste in the terrestrial environment is our topic of interest, as it can significantly contribute to the broader issue of plastic waste pollutants. Wind and surface runoff are the main factors affecting plastic movement in the terrestrial environment. On the other hand, land surfaces, as the resisting factors, have a role in facilitating the unique movement patterns. Our objectives are to simulate the motion rate and pattern of plastic movement by exposing five varieties of plastics to these driving and resisting variables. As foundational data, this study can be utilized to ascertain the probability of migration and accumulation in the terrestrial environment. Each plastic travels differently across different ground surfaces at various wind speed thresholds. For example, a plastic bag can be moved at 0.8 m/s on paved and bare terrain, while it requires 1.6 m/s to move a plastic bag on cutting grass. A plastic by surface runoff may already be in motion when driven at a 1 L/s rate. However, wind power will be more frequently encountered in the environment than runoff, which only occurs on rainy days. The data also shows varied patterns across various ground surfaces, i.e., how plastic waste is retained in vegetated regions, travels with soil particles in bare terrain, and is easily transported on paved terrain.

Keywords

Plastic
Driving factors
Resisting factors
Migration
Accumulation
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pmc1 Introduction

The world currently faces a crisis regarding plastic waste, with its generation continually increasing while the capability for proper management lags behind [1,2]. Furthermore, plastic waste inflicts severe environmental, social, economic and health consequences [[3], [4], [5], [6], [7], [8], [9]], emphasising the urgent requirement for practical solutions. Plastic waste can endanger animal health in terrestrial environments through ingestion [10,11], and clogged drainage systems, causing floods and blockages [12]. Plastic chemicals can also leak into groundwater from landfills, making it unsafe for consumption [13,14] and impairing plant growth by becoming a microbe medium [15]. Given its propensity for transboundary movement, unmanaged plastic waste poses a significant risk of contaminating water systems by clogging and disturbing river fish populations [16,17], and imposes a hazardous effect on wildlife in the ocean [11,18].

Due to their broad impact, monitoring and predictive analysis are pivotal in preventing, mitigating, and devising future solutions for plastic waste issues. They serve as essential inputs for implementing timely and location-appropriate preventive or remedial measures [19,20]. Numerous studies have sought to quantify and predict the accumulation of plastic in rivers and oceans [[21], [22], [23]], revealing that a substantial portion of plastic waste originates from terrestrial sources. However, discourse regarding the natural process by which plastic waste transport from terrestrial sources to water systems remains constrained.

Current research focuses on how plastic waste enters water bodies from land, highlighting wind and surface runoff as key routes [24]. Wind can move plastic over large distances, especially from open areas [25]. The Counter Measure Report highlights how wind drives plastic waste from Indian cities like Haridwar and Mumbai into rivers [26], similarly affecting the distribution of plastic waste along the Dutch Rhine-Meuse delta due to high wind speeds [27]. Wind also facilitates the movement of plastic bottles to the Seine River estuary in France [28], underscoring wind's significant role in spreading plastic pollution to various environments, including during extreme weather events [29]. Intense rainfall resulted in flooding across various sections, particularly in lowland regions, leading to the displacement of a substantial amount of plastic waste from upstream areas [30]. Heavy rain and floods, particularly in low-lying areas, further displace plastic waste into waterways, with surface runoff seen as another major pathway, especially during rainy seasons [[30], [31], [32]].

The research focuses on understanding how wind and runoff influence plastic transport in terrestrial environments, aiming to create effective mitigation strategies through models. It builds on prior work by examining the roles of plastic types, surface features, and topography [27]. Several studies have shown variables that can be the main parameters in moving plastic as the simulation considerations include ground surface variation, plastic shape [33], and slope steepness [34]. Noting that terrain may obstruct plastic movement, influenced by soil roughness and plastic geometry [[35], [36], [37], [38]]. Additionally, it will investigate how weather patterns affect plastic dispersion [39]. Furthermore, this study aims to ascertain: 1) the wind speed threshold and surface runoff discharge levels for plastic movement; 2) the rate of plastic movement driven by wind and surface runoff; and 3) the diversity of plastics in response to the driving and resisting variables.

Through simulation experiments and observation techniques, we aim to enhance our understanding of how wind and runoff dynamics shape plastic wastes' spatial distribution and fate on land. Ultimately, by advancing our knowledge of wind and runoff-affected plastic transport, this research endeavours to contribute to the development of modelling for addressing the pervasive problem of plastic pollution and safeguarding the integrity of terrestrial and aquatic ecosystems.

2 Material and methods

2.1 Plastic type

In this study, following up the study of Morales-Caseless et al. [21], five types of plastic were used in this simulation: bags, water bottles with cups, dry food packaging, mica food trays, and foam food containers (Table S1). The decision to limit the plastic length to between 20 and 40 cm was grounded in the belief that its mass and dimensions could influence its movement. Consequently, this study aims to standardize the width of each plastic item, enabling us to better account for variations in shape, density, mass, and flexibility or stiffness in subsequent analyses [40,41].

These five plastic types were chosen based on their prevalence in aquatic systems, ranking among the most commonly found plastics in the environment, and representing significant proportions of household plastic waste [21]. For the inclusive criteria, each plastic type must meet the following criteria. 1) Bags (LDPE) must be a single-use plastic in general (6.6g), 2) Bottles must be empty (air-filled) with a 600 ml capacity (13.3 g), 3) Dry food packaging must a multilayer plastic film composed of an aluminum layer (16.4 g); 4) Mica food tray must be transparent food container (8.4 g); 5) Foam food container are also food container that lighter but thicker than other plastic's type due to it PS polymer composition (4.8 g).

This study utilized the same type of plastic for each sample to ensure consistency in both results and instrumentation. This choice was informed by the types of plastic fragments observed in the research environment. Numerous other plastic types were excluded from the simulation, including cups, straws and stirrers, cup lids, and additional types of plastic bottles. It is due to non-alignment with dimensional criteria used in this study particularly the length and size.

2.2 Ground surface setting

In this study, the ground surface acts as the resisting factor, determined by two key parameters: the character of the ground surface and its slope [24,38]. Paved terrain, bare terrain, and cutting grass are the land surface features chosen for the study, and each simulation is carried out on flat and sloping terrain [24,34,38]. In this experiment, the paved terrain is generally asphalt road, and bare terrain is a terrain devoid of plant life, typically characterized by loose, granular rocks. In contrast, cutting grass refers to an area covered with grass trimmed to a maximum height of 3 cm. The land slope characteristics include an incline ranging from 18 to 23°. We conducted the simulation test on the selected natural ground surface to accurately represent actual ground conditions and simplify media preparation.

2.3 Experimental design

In this work, a simulation was conducted to replicate the movement of plastic waste on land, using the following driving factors: wind and surface runoff. This experiment generated wind from a fan [34,40,42] and a pipe-based fluid flow [43,44]. During the first wind simulation using regular fan electricity powered, with a 0.41 m diameter, equipped with a remote control that generates winds up to 6 m/s (measured at 10 cm in front of the fan). The area of wind simulation area was surrounded by a 1x1x6x m transportable wind tunnel to prevent the wind from the outside of the wind generator used (Fig. 1a). The wind tunnel can eliminate wind distraction by 73–100 % (Table S4).Fig. 1 Experimental design: a) Wind speed simulation and b) Surface runoff simulation.

Fig. 1

During the surface runoff simulation, surface runoff was obtained by pumping water through a pipe system and distributing it to a selected area to simplify the simulation process and the comparison measurement on each ground surface (Fig. 1b). The runoff simulation is restricted to sloping ground surfaces, where runoff flows from higher to lower elevations. We divided it into four sections measuring 1 × 5 m. Each section was constructed on the slopped general paved terrain and divided into four ground sections including paved terrain. Three other sections are a hardwood board coated with 1 cm of clay and sand mixture (bare terrain), 3 cm of synthetic grass (cutting grass), and 0.5 cm layer of plastic sheet fibber (control area). Besides, the elongated tank with dimensions of 0.3x1x0.3 m for the upper and below of each sectional area was constructed to ensure a constant input and output of water flow. Subsequently, a valve were installed on the final pipe, allowing them to be opened or closed as needed. However, surface runoff simulation requires a water supply and tools for directing the water. To streamline the simulation process, we set up the simulation area in a single location with several configurations.

2.4 Simulation procedure

This section describes the wind simulation and surface runoff simulation processes.

Wind Simulation. The measurements used in the wind simulation are divided into two stages: determining the wind speed threshold and evaluating the rate of plastic movement at three different wind speeds. First, we assess the minimum wind speed required to propel the plastic waste. In this regard, each plastic waste is positioned 5 m away from the fan. The plastic waste was moved in 20-cm increments toward the fan until the airflow was sufficient to propel it. The measured distance is then compared to the wind speed to analyze the relationship between distance and airflow. The second stage was determining the rate of plastic movement at 6 m/s wind speeds, which is the maximum wind speed the fan can generate. This technique was used to measure the speed of the plastic at each wind speed. Our assumptions suggest that plastic waste may move at speeds comparable to the wind speed. Subsequently, all observed wind speeds were compared with the Beaufort wind scale to assess their correlation.

Surface Runoff Simulation. In this experiment, the pump fills an elongated tank with water. Once the tank is full, water flows through each section. Before the simulation, a water flow rate test was conducted by dropping colored oil liquid into the flowing water. Then, the travel time was compared to the 5 m distance. Water charge and flow were adjusted by modifying the pump's suction capacity and the tap's rotation. The experiments used a factorial design, which differs from the wind speed threshold experiment due to equipment limitations in precisely adjusting minor variations for the runoff treatment. The simulation used 3 different flow rates, i.e. 0.01, 0.1, and 1 L/s, to determine the plastic flow rate through the surface runoff flow. The discharge is adjusted according to the possibility of rain and runoff conditions measured with low, medium, and heavy rainfall. We decided to concentrate only on runoff discharge. Our standard amount for runoff discharge is set at 0.01 L/s used a simple formula: Q = AV. Where, Q is the runoff discharge (m3/s), A is the wet area (m2), and V is the water flows speed (m/s). We added 0.01 L/s and 1 L/s as multiples of 10 from the baseline data. In this simulation, each plastic was also divided into three dimensions: 100 % (intact condition), 50 % (half part), and 25 % (quarter part). And final, the observation time was limited to 15 min. So when no plastic movement is found within that period, the simulation will be stopped, and the plastic will be declared not moving.

2.5 Record

A drone was used to record and assist in observing the simulation. It captured both simulation processes to monitor the plastic movement in each area. It was operated at 10–30 m altitude to achieve optimal image resolution [45]. Recorded data can improve the analysis accuracy for the measurements taken in the field. Furthermore, a calibration stick was used during the recording phase to compare the size of the field later in the analysis process.

2.6 Additional data: observation

An observational study was conducted to validate the simulations. The observations were conducted over two days in two chosen open areas, representing the ground surface factors. The location was an open area with various land surface characteristics: the first was cutting grass and asphalt, and the second was cutting grass, bare terrain, and asphalt. The observation started at 6 a.m., five types of plastic were positioned together at a central location determined by GPS. We then monitored the movement of the plastic waste during the first 15 min. Subsequent measurements and observations were conducted at 10 a.m. (morning measurement), 3 p.m. (noon), 6 p.m. (evening), and 6 p.m. (night) the next day. During those specific times, the wind speed exhibited several phenomena, including gradual increase, substantial increase, substantial decrease, gradual decrease, and ultimately drop to 0 m/s of a wind speed [39]. Wind and surface runoff are natural climate processes. Therefore, we used digital weather stations to record the data real-time.

2.7 Analysis

The primary method used for data analysis involves processing digital data. The video recorded from the drone was analyzed using the Tracker software (Video Analysis and Modelling Tools) (Fig. S5), which can provide an accurate plastic movement rate. Moreover, statistical tests were conducted, and the data were visualized using graphs in R Studio. The analysis included wind speed thresholds and plastic movement rates based on the results from Tracker analysis. Furthermore, ANOVA tests were conducted to compare the factors associated with each plastic type, driving factors, and ground surface factors. The Tukey test was chosen in this study as it is an advanced test used for pairwise comparisons when the ANOVA test reveals significant differences. The final step involved generating the observational tracking points using ArcGIS software.

2.8 Formula

The following equation is used as a wind speed conversion factor at the scope of the study to wind speeds at other altitudes [46]. Where v1 and v2 are the wind speed at a height of 10 m and directly above the surface (m/s), h1 and h2 are the height of the wind measurement at 10 m and the height directly above the surface (m), and z0 is the length of the ground surface roughness (m).(1) v2=v1ln(h2z0)ln(h1z0)

in addition to field measurements of discharge and runoff velocity, additional validation of the analysis can be achieved by employing the general equation for runoff discharge (Eq. (2)) and the Manning equation (Eq. (3) and Eq. (4)). The Manning equation calculates water runoff velocity based on runoff area (width and depth) and the land slope. Where Q is runoff discharge (m3/s), v is runoff velocity (m/s), n is Maning coefficient, R is hydraulic radius (m), P is length of wetted surface (m/m)(2) Q = vA

(3) v=1nR2/3S

(4) R=AP=A2y+b

3 Experimental result

3.1 Wind speed threshold

The wind speed threshold refers to the minimal wind speed required to set each plastic in motion influenced by driving factors and resisting factors (Fig. S1). When the wind speed threshold is lower, the plastic is easier to move with the wind. Fig. 2 shows the wind speed threshold required to propel each of plastic. There is a negative relationship between wind speed and distance. This means that as the distance increases, the wind speed reaching the plastic decreases. The minimum windspeed threshold in our analysis is 0.8 m/s (measured at 4.4 m from the fan), which can displace a plastic bag by 10 cm. We also observed that plastic bottles can move on their own on sloped paved and bare terrain even when there is no wind (0 m/s wind speed). This happens because their round shape moves due to gravity. However it can be stopped by obstacles like large stones or uneven ground.Fig. 2 Wind speed threshold of 5 types of plastic based on wind-propelling and ground surface factors.

Fig. 2

Plastic bags, despite having a higher density (0.93 g/cm3) compared to foam food containers (0.2 g/cm3), are propelled more efficiently by the wind due to their aerodynamic properties. The primary factor influencing this behavior is the difference in their surface areas exposed to the wind [36,37]. Although foam food containers have a larger vertical wind contact area (approximately 140 cm2), plastic bags offer a much larger horizontal surface area (about 1442 cm2), allowing for greater aerodynamic interaction. This interaction, as explained by Bernoulli's principle, suggests that the increased flow speed across the plastic bag's surface results in a lifting force due to reduced pressure. Floating plastic can receive more significant wind due to the influence of wind profiles at different heights. Consequently, plastic bags can ascend and catch more wind, which propels them further, despite their heavier mass compared to foam containers [47].

Fig. 2 also illustrates slightly how plastics are divided into groups. This assertion is further substantiated by the Tukey's test analysis, looking at all variables (Table S6), finds how these categories relate to their location (Fig. 3. 1). Tukey's test identifies three types of plastics (Table S7), grouped by how easily wind moves them. The first group includes plastic bags, moved by wind speeds of 0.8–1.3 m/s. The second group has plastic bottles and foam containers, affected by wind speeds of 1.1–2.3 m/s. The third group includes a mica food tray and dried food packaging, needing wind speeds of 2–3.7 m/s to move. Dried food packaging is similar in size to plastic bags, while mica trays are like foam containers but heavier. Despite their differences, higher wind speeds are needed to move the latter two types of plastics.Fig. 3 Plastic classification based on Tuckey test notation of wind speed threshold: 1) Three classes (aggregate calculation) and; 2) Two classes (focused on the flat area).

Fig. 3

Another analysis that focuses on the effects of wind on plastic items on flat ground (Table S11). It excludes a plastic bottle found on a sloped area. The analysis divides the plastics into two categories based on how easily the wind can move them (Fig. 3. 2). The first group includes plastics that the wind can move easily, needing an average wind speed of 1.1–1.4 m/s. The second group consists of plastics that require a higher wind speed of 2–3.2 m/s.

Ground surfaces and slopes affect how plastic moves, but in different ways. The same pattern of plastic movement appears on paved terrain and bare terrain. Although plastic can move more easily on paved terrain, the wind speed threshold values are not significantly different between these two ground surfaces. However, these wind speed threshold values significantly differ from the cutting grass ground surface. Plastic moves less because the grass can catch and hold the plastic (Table S7). The average wind speed thresholds for paved and bare terrain is reported as 1.13 ± 0.40 and 1.36 ± 0.39 m/s, respectively and 1.78 ± 0.46 m/s on cutting grass terrain. These findings align with the research conducted by Ledieu et al. (2022) [48], who also found a high possibility of plastics being entangled between grass and herb during the migratory process.

However, slope parameter (flat and sloped area) does not reveal a statistically significant differences even at 99 % confidence level. The wind flow on both the flat and sloped area is streamed over the surface and can be diminished because of turbulence. Turbulent wind can occur due to differences in pressure, wind deflection, and the convergence of winds from multiple directions [37].

3.2 Plastic rate through the wind speed

The second simulation is carried out to monitor the mobilization rate of plastics. The study looks at how fast plastics move at a wind speed of 6 m/s, using drones and Tracker software for measurements. The results show how far plastics travel in 3 s, using a method based on distance (Fig. 4). These 3 s follow the 3 s gust term, which refers to the peak wind speed measured in some certain area and becomes the recommended time to measure the wind speed by The World Meteorological Organization (WMO) [49].Fig. 4 The approximated distance of plastic mobilization at 6 m/s wind speed. Number in meter denoted as maximum mileage on 3 s wind simulation.

Fig. 4

Various plastics move differently by the wind; for example, plastic bags and dry food packages tend to slide while other plastics roll. Plastic bottles roll at first but change direction quickly because of their uneven shape. Even though plastic bags have the lowest wind speed threshold, their travelled distance is not the furthest compared to other plastics. This is because, at high wind speeds, aerodynamics through lift force begins after the wind blows a plastic bag. So, plastic bags only get a part of the strongest wind. Another thing that can also stop plastic bags from moving far is that if wind fills the bag, making it puff up, it gets more prominent, and the air drags it more, slowing it down.

All plastics show different mileage depending on the resisting factors. It is significantly different on the ground surface, but not on the slope (Table S9). The plastic groups observed on the paved terrain are consistent with the wind speed threshold result findings. However, the same pattern does not occur in bare terrain and cuting grass. Despite the aerodynamic issue, a plastic bag on bare terrain often ends up covered by sand, making it heavier. On cutting grass, the plastic tip is constantly entangled.

3.3 Surface runoff

The simulation involving surface runoff poses more challenges. We exclusively performed the simulation on the inclined terrain with flowing water to account for the presence of surface runoff and mobilized the plastics. We have applied the spray simulation as our preliminary study in line with the research by Nguyen et al. (2022) [44], but it is quite challenging to get the plastics movement response. This simulation is more suitable to small materials such as sand or microplastics, but not large-sized plastics. Our findings, highlighted in Table 1, revealed that plastics move effortlessly in control areas, akin to icy surfaces with very low friction, propelled by minimum surface runoff. At a discharge of 1 L/s (±0,53 m/s water flow rate), plastics can travel up to 5 m in 20 s, but at lower discharges, movement significantly decreases, showing no movement at 0.01 L/s after 15 min [50].Table 1 Surface runoff simulation results based on ground surfaces, discharge level, plastic types and dimension parameters.

Table 1

Water flow on various terrains leads to different conditions. When water discharge reaches 1 L/s, the flow height exceeds 0.5 cm, with the most force happen near the water sources. Early flow stages carry more plastic particles than the steady after [51]. On paved terrain, plastic slides with water, while on grass, it moves quickly due to water pushing it down and shortening the grass. Vegetation can divert and split the flow, possibly stopping plastic movement if not all of it is covered by water. However, studies suggest that dense and high vegetation can impede plastic movement [24,52,53], and matching water levels to grass height is necessary to free accumulated plastic on riverbanks [54].

When water flows over bare terrain, it can cause a lot of erosion, while plant roots and rocks might come up on the surface in forest areas. This erosion can either move plastic along with it or stop the plastic from moving because the emerging plant roots and rocks can get covered with sand. If the bare terrain is hit with water flowing at 1 L per second, it could be completely eroded away in just 5 s across a 5-m area, carrying plastic with it. When the water flow is slower, between 0.01 and 0.1 L per second, it tends to create small, random streams on the surface, causing less erosion. This minor effect of water on bare terrain was also noted in a study by Dai et al. (2022) [55].

3.4 Observational investigation

Field observations aim to understand real-world conditions better, focusing on how plastic moves, including how far it goes, its direction, and obstacles it encounters. Both experiments and observations agree closely, showing that plastic bags, foam containers, mica trays, dry food packaging, and bottles vary in how far they can travel, in that order (Fig. 5). The time of day affects how much plastic moves (Fig. 6), with more displacement happening in the morning and less in the evening, due to changes in wind speed related to temperature. As it gets warmer from morning to noon, the wind speeds up (because of the Bernoulli principle) and then slows down by evening, stopping at night.Fig. 5 Observational report from June 3–4, 2023, focusing on the distance travelled on different types of plastic. A table highlights these distances, categorized by daily time profiles noted in the report.

Fig. 5

Fig. 6 Wind profile over the observation period (June 3–4, 2023).

Fig. 6

The distance travelled by one type of plastic relative to a different kind of plastic is a fascinating fact that can be discussed in the analysis of the observational data. It got stuck behind a 30 cm tall plant in a drainage system that's half a meter deep, as shown in an illustration (Fig. 5, point 1 to 2). The plastic bag was later able to move again and got unstuck further down, 1.5 m along the drainage depth (Fig. 5, points 3 to 8). The idea is that when there's a lot of space in the drainage, water flow can cause turbulence, which in turn quickly spreads out the wind, helping the plastic to move.

During the observation, the highest wind speed recorded by the weather station was 5 m/s, measured at 2 m above the ground (Fig. 6). However, when adjusting this speed to a Beaufort standard, it lowers to about 1.1 m/s. At this speed, the wind can move light plastic items like plastic bags and foam food container. On the other hand, observational studies on surface discharge parameters are limited due to the unreliability of rainfall forecasts. Regarding the surface discharge process that occurs naturally due to falling rain, it is essential to note that plastic transfer does not happen in flat areas, so sloped areas are crucial. Even when the rainfall reached 102 mm/h, no plastic movement was observed at any observation time.

4 Discussion

4.1 The role of wind as a driving force

This study aimed to support earlier research by Mellink et al. (2022) [38], on wind speeds by doing tests on three types of ground: paved terrain as urban land, bare terrain as bare land, and cutting grass as grass/shrub land. Agricultural land and forests were not included due to the limitation equipment, specifically the inability of the fan to provide sufficient wind speed. Our result found the wind speed threshold value differ as much as 91 % in comparison to the reference value (Fig. 7).Fig. 7 Wind speed threshold comparison.

Fig. 7

Differences in wind speed results can be due to various factors like the flexibility of plastic, how values are determined, and estimation biases. The Beaufort scale could help determine the wind speed threshold differences. Wind speed varies with height, so it's essential to measure it precisely [40,56,57]. The standard Beaufort scale measurements are 10 m above ground level [46]. Still, wind speed thresholds in our result are taken at 0.01 m above ground level. We converted the reference wind speeds from 10 to 0.1 m above ground level. The wind speed threshold between these two different measurements hit up to 50 % different and up to 82 % at 0.01 m (Table 2). We found that the experimental results' wind speed threshold showed values close to the estimated reference wind speed threshold at height conversions of 0.1 and 0.01 m/s. One of the values we found was the lowest wind speed threshold at 0.8 m/s, which aligns with our observations regarding the type of plastic bag. The results we obtained can also become input for developing the model where the type of plastic can be considered one of the parameters.Table 2 Wind speed gradient profile determined by the ground reference surface variation.

Table 2Ground surface	Slope	Wind speed (m/s)	
h10m	h0,1m	h0,01m	
Paved terrain	Flat	8,8	3,9	1,5	
Slope	4,6	2,1	0,8	
Bare terrain	Flat	6,6	3,0	1,1	
Slope	2,4	1,1	0,4	
Cutting grass	Flat	10	4,5	1,7	
Slope	5,8	2,6	1,0	

Based on the conversion results at a height of 10 m, the wind speed threshold analysis results can be compared to the Beaufort scale (Table S11). The results show (Table S9) that plastic bags and foam food containers can move at level 4 on the Beaufort scale (moderate breeze). The other three plastic types can move at level 6 on the Beaufort scale (strong breeze). Based on the ground surface variation (Table S10), on average, plastic can move at levels 4, 5 and 7 Bf on paved terrain, bare terrain, and cutting grass, respectively.

Moving to the observational result. The study was conducted on the field growth by grasses, about 5 cm tall. This grass spreads by growing new roots and shoots from each segment. However, when it is cut, the uneven grass tips can catch plastic waste. The plastic gets stuck because it's flexible and fills the spaces between the grass. Experts agree that this dense vegetation can trap and collect plastic waste [21,24,48]. Past research has shown that places with many plants near rivers can gather plastic bottles [48], significantly when the water movement is affected by boats. The height of the plants is vital because plastic will only move over them if it's high enough [58]. In areas like riverbanks and mangroves, the plant's roots and stems also play a big part in catching plastic waste, helping to stop it from moving around [59].

The results from a detailed study suggest that how we design models to understand how plastic waste moves on land can be improved by considering different types of plastics and ground surface variation. This modelling is instrumental in applications in open areas. The study also points out that obstacles like buildings and cars can change wind patterns in cities, affecting how plastic travels [46]. Additionally, our research shows that poorly managed landfill sites, especially in developing countries, have a high chance of allowing plastic waste to get into water bodies due to the inference of wind-propelling [18]. The use of fences as barriers can prevent the plastic waste, especially plastic bags to leakage.

The interim results of this study also demonstrate the potential for boundary fences installed as standard in the construction of sanitary landfills to function as an effective buffer and prevent the further release of plastic waste into the environment; however, even with buffers, plastic bags have a high potential to be released from the management system because they are easily lifted by the wind. This research is still limited to single plastic and will require more wind and discharge for plastics accumulating in a single container. However, river surface drainage with an estimated discharge of 10 L/s has recently released the accumulation of plastic.

The principal finding of this experimental analysis is the wind speed threshold as a basis for consideration and comparison of wind speed in the field, where wind speed variations can be distinct and greater than the threshold established by this study. The direction of the wind (the resultant force) is also an essential consideration for pinpointing the movement of the plastic waste. However, additional case studies in various locations are required to supplement more specific data. We are also concerned with the runoff parameter, which needs more observational study, specifically in the drainage system or on the surface that has a higher flooding possibility. As model input material, additional details in the trajectory process require supporting data such as the size of waste generation, the identification of potential areas that can be affected by the unmanaged plastic waste, the distance plastic travels from land to bodies of water, average daily wind speed and direction, precipitation, and land ground surface variation.

Different locations have varying wind speeds, which can greatly affect where plastic waste ends up. The direction of the wind plays a crucial role as well. More case studies in different places are needed to gather precise data on this issue. Additionally, there's a need to study water runoff more closely, as it can carry plastic waste, especially in areas prone to flooding. To better understand how plastic waste moves, data on the amount of waste, where it could go, and environmental factors like wind speed, rainfall, and the terrain are needed. Different environments might experience the impact of wind on plastic waste movement differently. For example, a study by Garello et al. [33] highlighted that in river environments, the movement of water has a bigger role in transporting plastic waste than previously thought. Our study suggests looking closely at changes over time rather than just at one place to better understand how and why plastic spreads.

5 Conclusion

This study is the first approach to understanding the movement of plastics through wind speeds and surface runoff by a simulation study. Overall, wind-propelling is a critical key to migrating the plastics which is more frequently encountered in the environment than runoff, which only occurs on rainy days. It can move a plastic bag and a foam food container at level 4 Beaufort scale (5.5–7.9 m/s), while the others need more than this Beaufort level. On the other hand, surface runoff can move plastics at a 1 L/s rate (0.53 m/s current rate), which is the highest probability. We also found that various ground surfaces provide different restrictions. Plastics are retained in the vegetational area or move along with soil on bare terrain and move easily on asphalt roadways. At some point, steepness in this study does not affect plastic movement compared to other studies.

This research aims to provide fundamental data for developing analytical models, specifically focusing on the driving factors and understanding the movement and accumulation of plastic waste in the environment. The study results suggest several factors that can be incorporated into the model analysis, including wind speed thresholds, plastic-type categories, and ground surface characteristics. Some types of plastic may be categorized into several groups to simplify the modelling process. In addition, ecosystem disparities must be comprehensively considered due to the different findings from the other studies. The primary objective of the simulation is to comprehensively assess the migration of plastic waste entering the ocean, with a particular focus on the largest plastic waste-producing countries. Notably, a significant portion of this plastic waste originates from household sources on land.

Data availability statement

The authors confirm that the data supporting the findings of this study are available within the article and its supplementary materials.

CRediT authorship contribution statement

Zayinatun Biladiyah Al Khoeriyah: Writing – original draft, Investigation, Funding acquisition, Formal analysis. Emenda Sembiring: Writing – review & editing, Validation, Supervision, Methodology, Formal analysis, Data curation, Conceptualization.

Declaration of competing interest

The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Emenda Sembiring reports financial support was provided by 10.13039/501100015689 Bandung Institute of Technology Faculty of Civil and Environmental Engineering. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Appendix A Supplementary data

The following is the supplementary data to this article:Multimedia component 1

Multimedia component 1

Acknowledgements

The research was partially funded by PPMI, Contract No 67.1/IT1. C06/SK-KP.01/2022, Faculty of Civil and Environmental Engineering, 10.13039/501100015689 Bandung Institute of Technology and Indonesia Endowment Fund for Education (LPDP) for Ms Koeriyah scholarship.

Appendix A Supplementary data to this article can be found online at https://doi.org/10.1016/j.heliyon.2024.e36502.
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References

1 Browning S. Beymer-Farris B. Seay J.R. Addressing the challenges associated with plastic waste disposal and management in developing countries Current Opinion in Chemical Engineering 32 2021 100682 10.1016/j.coche.2021.100682
2 Kedzierski M. Frère D. Le Maguer G. Bruzaud S. Why is there plastic packaging in the natural environment? Understanding the roots of our individual plastic waste management behaviours Sci. Total Environ. 740 2020 139985 10.1016/j.scitotenv.2020.139985
3 Falsini S. Colzi I. Chelazzi D. Dainelli M. Schiff S. Papini A. Coppi A. Gonnelli C. Ristori S. Plastic is in the air: impact of micro-nanoplastics from airborne pollution on Tillandsia usneoides (L.) L. (Bromeliaceae) as a possible green sensor J. Hazard Mater. 437 2022 129314 10.1016/j.jhazmat.2022.129314
4 Ghosh D. Sarkar A. Basu A.G. Roy S. Effect of plastic pollution on freshwater flora: a meta-analysis approach to elucidate the factors influencing plant growth and biochemical markers Water Res. 225 2022 119114 10.1016/j.watres.2022.119114
5 Lam T.W.L. Tsui Y.C.J. Cheng Y.L. Ma A.T.H. Fok L. Microplastic contamination in edible clams from popular recreational clam-digging sites in Hong Kong and implications for human health Sci. Total Environ. 875 2023 162576 10.1016/j.scitotenv.2023.162576
6 Roman L. Paterson H. Townsend K.A. Wilcox C. Hardesty B.D. Hindell M.A. Size of marine debris items ingested and retained by petrels Mar. Pollut. Bull. 142 2019 569 575 10.1016/j.marpolbul.2019.04.021 31232340
7 Thibault M. Hoarau L. Lebreton L. Le Corre M. Barret M. Cordier E. Ciccione S. Royer S.-J. Ter Halle A. Ramanampamonjy A. Jean C. Dalleau M. Do loggerhead sea turtle (Caretta caretta) gut contents reflect the types, colors and sources of plastic pollution in the Southwest Indian Ocean? Mar. Pollut. Bull. 194 2023 115343 10.1016/j.marpolbul.2023.115343
8 Tong Y. Lin L. Tao Y. Huang Y. Zhu X. The occurrence, speciation, and ecological effect of plastic pollution in the bay ecosystems Sci. Total Environ. 857 2023 159601 10.1016/j.scitotenv.2022.159601
9 McIlgorm A. Raubenheimer K. McIlgorm D.E. Nichols R. The cost of marine litter damage to the global marine economy: insights from the Asia-Pacific into prevention and the cost of inaction Mar. Pollut. Bull. 174 2022 113167 10.1016/j.marpolbul.2021.113167
10 Sembiring E. Fareza A.A. Suendo V. Reza M. The presence of microplastics in water, sediment, and milkfish (chanos chanos) at the downstream area of citarum river, Indonesia Water Air Soil Pollut. 231 2020 10.1007/s11270-020-04710-y
11 Dhairykar M. Jawre S. Rajput N. Impact of plastic pollution on wildlife and its natural habitat Pharm. Innov. 2022 141 143
12 Kehinde O. Ramonu O.J. Babaremu K.O. Justin L.D. Plastic wastes: environmental hazard and instrument for wealth creation in Nigeria Heliyon 6 2020 e05131 10.1016/j.heliyon.2020.e05131
13 Rai M. Pant G. Pant K. Aloo B.N. Kumar G. Singh H.B. Tripathi V. Microplastic pollution in terrestrial ecosystems and its interaction with other soil pollutants: a potential threat to soil ecosystem sustainability Resources 12 2023 67 10.3390/resources12060067
14 Kumar A. Yu Z.-G. Thakur T.K. Microplastic pollutants in terrestrial and aquatic environment Environ. Sci. Pollut. Res. 30 2023 107296 107299 10.1007/s11356-023-29210-4
15 Baho D.L. Bundschuh M. Futter M.N. Microplastics in terrestrial ecosystems: moving beyond the state of the art to minimize the risk of ecological surprise Global Change Biol. 27 2021 3969 3986 10.1111/gcb.15724
16 Bauer-Civiello A. Critchell K. Hoogenboom M. Hamann M. Input of plastic debris in an urban tropical river system Mar. Pollut. Bull. 144 2019 235 242 10.1016/j.marpolbul.2019.04.070 31179993
17 Carson H.S. Lamson M.R. Nakashima D. Toloumu D. Hafner J. Maximenko N. McDermid K.J. Tracking the sources and sinks of local marine debris in Hawai‘i Mar. Environ. Res. 84 2013 76 83 10.1016/j.marenvres.2012.12.002 23268778
18 Jambeck J.R. Geyer R. Wilcox C. Siegler T.R. Perryman M. Andrady A. Narayan R. Law K.L. Plastic waste inputs from land into the ocean Science 347 2015 768 771 10.1126/science.1260352 25678662
19 Erdle L.M. Eriksen M. Monitor compartments, mitigate sectors: a framework to deconstruct the complexity of plastic pollution Mar. Pollut. Bull. 193 2023 115198 10.1016/j.marpolbul.2023.115198
20 Shim W.J. Kim S.-K. Lee J. Eo S. Kim J.-S. Sun C. Toward a long-term monitoring program for seawater plastic pollution in the north Pacific Ocean: review and global comparison Environmental Pollution 311 2022 119911 10.1016/j.envpol.2022.119911
21 Morales-Caselles C. Viejo J. Martí E. González-Fernández D. Pragnell-Raasch H. González-Gordillo J.I. Montero E. Arroyo G.M. Hanke G. Salvo V.S. Basurko O.C. Mallos N. Lebreton L. Echevarría F. van Emmerik T. Duarte C.M. Gálvez J.A. van Sebille E. Galgani F. García C.M. Ross P.S. Bartual A. Ioakeimidis C. Markalain G. Isobe A. Cózar A. An inshore–offshore sorting system revealed from global classification of ocean litter Nat. Sustain. 4 2021 484 493 10.1038/s41893-021-00720-8
22 Isobe A. Iwasaki S. The fate of missing ocean plastics: are they just a marine environmental problem? Sci. Total Environ. 825 2022 153935 10.1016/j.scitotenv.2022.153935
23 Li W.C. Tse H.F. Fok L. Plastic waste in the marine environment: a review of sources, occurrence and effects Sci. Total Environ. 2016 566 567 10.1016/j.scitotenv.2016.05.084 333–349
24 Meijer L.J.J. van Emmerik T. van der Ent R. Schmidt C. Lebreton L. More than 1000 rivers account for 80% of global riverine plastic emissions into the ocean Sci. Adv. 7 2021 eaaz5803 10.1126/sciadv.aaz5803
25 Chen Q. Fei X. Effective reduction of land-to-ocean plastic leakage in Thailand from 2000 to 2019 and implications for low- and middle-income countries Resour. Conserv. Recycl. 198 2023 107204 10.1016/j.resconrec.2023.107204
26 Counter Measure Chapter 1: Material Cycle of Plastic 2020
27 Roebroek C.T.J. Laufkötter C. González-Fernández D. van Emmerik T. The quest for the missing plastics: large uncertainties in river plastic export into the sea Environmental Pollution 312 2022 119948 10.1016/j.envpol.2022.119948
28 Tramoy R. Gasperi J. Colasse L. Noûs C. Tassin B. Transfer dynamics of macroplastics in estuaries – new insights from the Seine estuary: Part 3. What fate for macroplastics? Mar. Pollut. Bull. 169 2021 112513 10.1016/j.marpolbul.2021.112513
29 Mardon A. The Current and Past Impact of Tornadoes in Society GM 2021 Press Edmonton, AB
30 Singh D.D. Causes, Impacts, Risk and Mitigation of Urban Flood Management in India 2022
31 Pathak G. Nichter M. Hardon A. Moyer E. Latkar A. Simbaya J. Pakasi D. Taqueban E. Love J. Plastic pollution and the open burning of plastic wastes Global Environ. Change 80 2023 102648 10.1016/j.gloenvcha.2023.102648
32 Lebreton L.C.M. Zwet J.V.D. Damsteeg J.W. Slat B. Andrady A. Reisser J. River plastic emissions to the world's oceans Nat. Commun. 8 2017 10.1038/ncomms15611
33 Garello N. Blettler M.C.M. Espínola L.A. Wantzen K.M. González-Fernández D. Rodrigues S. The role of hydrodynamic fluctuations and wind intensity on the distribution of plastic debris on the sandy beaches of Paraná River, Argentina Environmental Pollution 291 2021 118168 10.1016/j.envpol.2021.118168
34 Mellink Y.A.M. Van Emmerik T.H.M. Mani T. Wind- and rain-driven macroplastic mobilization and transport on land Sci. Rep. 14 2024 3898 10.1038/s41598-024-53971-8 38365993
35 Maramizonouz S. Nadimi S. Drag force acting on ellipsoidal particles with different shape characteristics Powder Technol. 412 2022 117964 10.1016/j.powtec.2022.117964
36 Viola I.M. Arredondo-Galeana A. Pisetta G. The force generation mechanism of lifting surfaces with flow separation Ocean Engineering 239 2021 109749 10.1016/j.oceaneng.2021.109749
37 Wu B. Wang Q. Liao H. Li Y. Li M. Flutter derivatives of a flat plate section and analysis of flutter instability at various wind angles of attack J. Wind Eng. Ind. Aerod. 196 2020 104046 10.1016/j.jweia.2019.104046
38 Mellink Y. van Emmerik T. Kooi M. Laufkötter C. Niemann H. The Plastic Pathfinder: a macroplastic transport and fate model for terrestrial environments Front. Environ. Sci. 10 2022 979685 10.3389/fenvs.2022.979685
39 Kutty S.S. Khan M. Ahmed M.R. Wind energy resource assessment for Suva, Fiji, with accurate Weibull parameters Energy Explor. Exploit. 37 2019 1009 1038 10.1177/0144598719842379
40 Farsang A. Duttmann R. Bartus M. Szatmári J. Barta K. Bozsó G. Estimation of soil material transportation by wind based on in situ wind tunnel experiments J. Environ. Geogr. 6 2013 13 20 10.2478/jengeo-2013-0002
41 Isobe A. Kubo K. Tamura Y. Kako S. Nakashima E. Fujii N. Selective transport of microplastics and mesoplastics by drifting in coastal waters Mar. Pollut. Bull. 89 2014 324 330 10.1016/j.marpolbul.2014.09.041 25287228
42 Rezaei M. Riksen M.J.P.M. Sirjani E. Sameni A. Geissen V. Wind erosion as a driver for transport of light density microplastics Sci. Total Environ. 669 2019 273 281 10.1016/j.scitotenv.2019.02.382 30878934
43 Kalmikov A. Wind power fundamentals Wind Energy Engineering 2017 Elsevier 17 24 10.1016/B978-0-12-809451-8.00002-3
44 Nguyen N.A.T. Sudjono P. Kusuma G.T. Gunawan A.Y. Muntalif B.S. Conservative solute transport from soil to runoff flow in a steep slope area IJTech 9 2018 1429 10.14716/ijtech.v9i7.2458
45 Andriolo U. Topouzelis K. Van Emmerik T.H.M. Papakonstantinou A. Monteiro J.G. Isobe A. Hidaka M. Kako S. Kataoka T. Gonçalves G. Drones for litter monitoring on coasts and rivers: suitable flight altitude and image resolution Mar. Pollut. Bull. 195 2023 115521 10.1016/j.marpolbul.2023.115521
46 Kent C.W. Grimmond C.S.B. Gatey D. Barlow J.F. Assessing methods to extrapolate the vertical wind-speed profile from surface observations in a city centre during strong winds J. Wind Eng. Ind. Aerod. 173 2018 100 111 10.1016/j.jweia.2017.09.007
47 Hesp P.A. Dong Y. Cheng H. Booth J.L. Wind flow and sedimentation in artificial vegetation: field and wind tunnel experiments Geomorphology 337 2019 165 182 10.1016/j.geomorph.2019.03.020
48 Ledieu L. Tramoy R. Mabilais D. Ricordel S. Verdier L. Tassin B. Gasperi J. Macroplastic transfer dynamics in the Loire estuary: similarities and specificities with macrotidal estuaries Mar. Pollut. Bull. 182 2022 114019 10.1016/j.marpolbul.2022.114019
49 Lombardo F.T. History of the peak three-second gust J. Wind Eng. Ind. Aerod. 208 2021 104447 10.1016/j.jweia.2020.104447
50 Mills A. The coefficient of friction, particularly of ice Phys. Educ. 43 2008 392 10.1088/0031-9120/43/4/006
51 Sugiura M. Takada H. Takada N. Mizukawa K. Tsuyuki S. Furumai H. Microplastics in urban wastewater and estuarine water: importance of street runoff EMCR 1 2021 54 65 10.5985/emcr.20200006
52 Duncan E.M. Davies A. Brooks A. Chowdhury G.W. Godley B.J. Jambeck J. Maddalene T. Napper I. Nelms S.E. Rackstraw C. Koldewey H. Message in a bottle: open source technology to track the movement of plastic pollution PLoS One 15 2020 e0242459 10.1371/journal.pone.0242459
53 Luo J. Zhou X. Rubinato M. Li G. Tian Y. Zhou J. Impact of multiple vegetation covers on surface runoff and sediment yield in the small basin of nverzhai, hunan province, China Forests 11 2020 329 10.3390/f11030329
54 Kervroëdan L. Armand R. Saunier M. Ouvry J.-F. Faucon M.-P. Plant functional trait effects on runoff to design herbaceous hedges for soil erosion control Ecol. Eng. 118 2018 143 151 10.1016/j.ecoleng.2018.04.024
55 Dai Z. Huang K. Jiang L. Li J. Yu F. Chen S. Shear strength characteristics of clay-gravel layer and its slope failure law and mechanism Front. Earth Sci. 10 2022 865697 10.3389/feart.2022.865697
56 Tasneem Z. Al Noman A. Das S.K. Saha D.K. Islam MdR. Ali MdF. R Badal MdF. Ahamed MdH. Moyeen S.I. Alam F. An analytical review on the evaluation of wind resource and wind turbine for urban application: prospect and challenges Developments in the Built Environment 4 2020 100033 10.1016/j.dibe.2020.100033
57 Zhang Z. Wang K. Chen D. Li J. Dickinson R. Increase in surface friction dominates the observed surface wind speed decline during 1973–2014 in the northern hemisphere lands J. Clim. 32 2019 7421 7435 10.1175/JCLI-D-18-0691.1
58 Isobe A. Azuma T. Cordova M.R. Cózar A. Galgani F. Hagita R. Kanhai L.D. Imai K. Iwasaki S. Kako S. Kozlovskii N. Lusher A.L. Mason S.A. Michida Y. Mituhasi T. Morii Y. Mukai T. Popova A. Shimizu K. Tokai T. Uchida K. Yagi M. Zhang W. A multilevel dataset of microplastic abundance in the world's upper ocean and the Laurentian Great Lakes Micropl.&Nanopl. 1 2021 16 10.1186/s43591-021-00013-z
59 Moniuszko H. Malonga W.A.M. Koczoń P. Thijs S. Popek R. Przybysz A. Accumulation of plastics and trace elements in the mangrove forests of bima city bay, Indonesia Plants 12 2023 462 10.3390/plants12030462 36771545
