Where is litter most found

Littering is the improper disposal of waste products. Littering can happen intentionally or unintentionally, but both have environmental consequences. Litter can take a variety of forms, but some items are littered more frequently than others. In a study by Keep America Beautiful , researchers found that the most littered items include:. While But why do people intentionally litter? The justification behind littering is quite simple and generally boils down to one of four reasons:.

Other than just being unsightly, litter can cause serious consequences for the environment. As litter degrades, chemicals and microparticles are released. For example, cigarette butts can contain chemicals such as arsenic and formaldehyde.

These poisons can make their way into the soil and freshwater sources, impacting both humans and animals. In addition to water and soil pollution, litter can also pollute the air.

These emissions can cause respiratory issues, other health problems, and even be a starting base for acid rain. Animals are innocent victims affected by litter every day. Researchers estimate that over one million animals die each year after ingesting, or becoming entrapped in, improperly discarded trash.

Plastics are usually divided into three categories: plastics in use, post-consumer managed plastic waste, and mismanaged plastic waste Geyer et al. Mismanaged plastic waste MPW is defined as plastic material littered, ill-disposed, or from uncontrolled landfills.

Plastic debris enters the sea from the coastal environment through runoff, winds, and gravity Jambeck et al. There are, however, few direct measurements of plastic entering the ocean and one has to rely on conceptual frameworks Jambeck et al. This lack of data on waste generation, characterization, collection, and disposal, especially outside of urban centers, leads to uncertainties Jambeck et al.

Most of our understanding on the motion of floating marine debris comes from numerical simulations Hardesty et al. Given the scarcity of observational data, numerical models can be used to simulate the motions of debris and test scenarios.

In this paper, we use particle tracking simulations to address questions that are of tremendous interest to the United Nations and the international community as they seek to track, identify, and eventually attend to the major sources of marine plastics in the ocean. The questions we address in this paper are:. Where does MPW released into the ocean by a given country go? Where does MPW found on the coastline of a given country come from? The last section provides a summary and discusses the limitations of the current model.

The global framework we use to track marine litter is OceanParcels v2. OceanParcels v2. NCODA uses a three-dimensional 3D variational scheme and assimilates available satellite altimeter observations, satellite, and in-situ sea surface temperature as well as in-situ vertical temperature and salinity profiles from Expendable Bathythermographs XBTs , Argo floats, and moored buoys Cummings and Smedstad, Surface information is projected downward into the water column using Improved Synthetic Ocean Profiles Helber et al.

The horizontal resolution and the frequency for the GOF3. For details on the ocean circulation model validation, the reader is referred to Metzger et al.

Plastic debris in the ocean is usually assumed to be from land-based sources, although some studies have suggested that sea-based sources also play an important role e. No matter the source, the primary challenge of modeling the global displacement of marine litter are the large uncertainties associated with the amount and location of mismanaged plastic waste MPW entering the ocean.

In this paper, we consider only the land-based sources. In order to derive meaningful information from the numerical simulation and address the above questions, one needs to be able to seed the model with plastic waste entering the ocean that is representative of each country and have been computed in a consistent manner globally.

At the present time, there are four studies that can provide a first-order estimate of the current global plastic waste input from land into the ocean: Jambeck et al. However, these studies all differ in their estimates of MPW input into the ocean. Starting with the earlier study by Jambeck et al. The calculation is based on a World Bank dataset Hoornweg and Bhada-Tata, on country-specific waste generation and management. Jambeck et al. Mismanaged waste is defined as material that is either littered or inadequately disposed of, meaning that it is not formally managed.

This includes disposal in dumps or open, uncontrolled landfills, where waste is not fully contained. Mismanaged waste can eventually enter the ocean via inland waterways, wastewater outflows, and transport by wind or tides. Assuming no improvements to the waste management infrastructure, the cumulative quantity of plastic waste available to enter the marine environment from land was predicted to increase by an order of magnitude by But plastics can also enter via rivers. Lebreton et al. In addition, they estimate at least 0.

Schmidt et al. The spatial distribution of the Schmidt et al. They estimate that between 60 and 99 Mt of MPW were produced globally in see the annual distribution of MPWs from coastal regions in Figure 1A and that this figure could triple by One of the main motivations for that study was to quantify the fraction of MPW generated in coastal areas against the fraction generated inland that may reach the oceans via rivers see river distribution in Figure 1B.

Following Jambeck et al. This value converted to an annual global input of MPW to the ocean from the coastal regions to be between 3. However, as stated earlier, estimating MPW associated with the population within a fixed distance from the coast 50 km, as in Jambeck et al.

Therefore, as shown by Lebreton et al. Figure 1. Distribution of the annual mismanaged plastic waste input from A the coastal regions 50 km from the coastline based on Lebreton and Andrady and B the inland regions through rivers based on Lebreton et al. In summary, while the four studies provide different estimates of MPW reaching the ocean, they are consistent.

As indicated by Schmidt et al. There are, of course, large uncertainties associated with the numbers provided by the above studies, but they provide a globally consistent database that can be used to seed our model.

For this study, we derived MPW inputs for the model using Lebreton and Andrady for the coastal regions within 50 km from the coastline; Figure 1A ; Lebreton et al. In total, we release 28, particles each month along the coastline representing the 5.

For the indirect input Figure 1B , we use the midpoint estimates for the global river catchments assembled by Lebreton et al. In total, we release 3, particles each month at the river mouth, representing the 1. For a review of the physical oceanography associated with the transport of floating marine plastics and of all the processes that affect transport, the reader is referred to van Sebille et al. In short, the particles are moved around by ocean currents, surface wave induced Stokes drift, and wind drag.

A full account of the Stokes drift, which is induced by surface gravity waves in the direction of wave propagation see review by van den Bremer and Breivik , for detail , would require an accurate wave model. However, the wave-induced Stokes drift can be assumed to act in the same direction of the wind e.

Pereiro et al. This is in agreement with Ardhuin et al. The magnitude of the contribution does depend on the buoyancy ratio of the plastic object and the sea water, i. All particles are advected with a fourth-order Runge-Kutta scheme using a one-hour time step. One additional factor that needs to be taken into account when modeling MPW is the time it takes for plastics to break down into smaller pieces under the combined actions of waves and effects of sunlight. These micro or nano plastics end up either in suspension in the water column e.

To account for those complex processes that ultimately lead to the removal of the MPW from the sea surface where the abundance of the MPW is observed and the movement of MPW is simulated , we apply a simple, hypothetical exponential decay function to the weight mass.

After experimentation and comparison to observations see discussion in next section , we adopted an e-folding time scale of five years. This implies that These particles represent a total of 3. After release, using OceanParcels v2. All particles are integrated from the release point in to the end of The results presented in this section therefore correspond to a year accumulation of MPW in the ocean.

Of the MPW released during —, Not surprisingly, we find that the wind and waves induced motions are primarily responsible for the beaching Dobler et al. Figure 2. Out of the total of 3,, released particles, 2,, end up on the beach during the year integration. The question then arises as to whether the amount of the modeled MPW remaining in the ocean is comparable to the observations. There are very few observations on MPW distribution in the open oceans and whatever data exists come with large uncertainties.

Figure 3 displays the distribution of the modeled MPW concentration at the end of the year accumulation. The general pattern i. High concentrations of the modeled MPW are also found in the northern Indian Ocean and in the marginal seas that connect the Pacific and Indian Oceans. To our knowledge, there are no direct observations in these regions, but this should not come as a surprise given the fact that a majority of the MPW mass that enters the ocean is from the surrounding South and East Asian countries.

This value is of the same order as the highest concentration reported in Lebreton et al. Figure 3. Figure 4. Figure 3 represents only a snapshot the MPW concentration at the end of the year accumulation in and it is important to note that, as reported by Maes et al.

Figure 5. The overall distribution is quite close to that seen in Figure 3 and agrees well with previously published modeling studies e. Figure 6. In this section, we use the model to address the questions raised in the introduction: 1 where does MPW released into the ocean by a given country go and 2 where does MPW found on the coastline of a given country come from.

Because observational data were collected on its beaches Ryan, , which can be used to validate the model, we use Kenya as an example in this section. The statistics for all world countries on MPW destinations and beached MPW sources are provided in the supplement to this article.

The figure is divided into two panels, Figure 7A shows the averaged concentration for those particles that remained at sea at the end of , while Figure 7B shows the averaged concentration for those particles that ended up on the beach major countries outlined in red at the end of The distribution in these two figures is quite similar, which implies that most particles follow a similar pathway: first, they flow northeastward into the Arabian Sea and subsequently into the Bay of Bengal, depending on the monsoon currents in the north Indian Ocean, and then eastward following the Equatorial Counter Current e.

One small difference between the two panels is that some MPW that remains in the ocean is trapped in the subtropical gyre of the South Indian Ocean or escapes into the South Atlantic Ocean via the Agulhas current and associated eddies. Figure 7. Last up on our list is glass beverage bottles as well as their metal caps. Around , glass bottles and , metal bottle caps are collected from our coastlines every year. While the glass bottles are easily recycled, the metal caps are more difficult to recycle.

There may be a bottling plant near you that will take them back, but to our knowledge, no municipal recycling program will take them back. Just like with plastic drinking containers, your best bet is to say no to the glass and instead use reusable beverage containers. Previous Post. Next Post. Sustainability 2 min read. Cigarette butts Each year, more than 2 million cigarettes are found littering our coastlines.