Microplastics In The Urban Water System Of Pontianak Indonesia

This title (paper) has been presented at the 2nd International k@Borneo Conference 2021 organised by Pustaka Negeri Sarawak that has been held virtually on 14 and 15 September 2021. This paper been prepared by Kiki P. Utomo and Dita Fakhrana from Universitas Tanjungpura, Indonesia.

Abstract

Pontianak City is a city that has cultural heritage in the form of river and canals. The growing threat to its canals is microplastic pollution. Microplastics are plastic particles with a size of less than 5 mm. Because of its size, microplastic could easily entering the food chain and combine with other substances to form new pollutants that are harmful to human health and ecosystems.

To study plastic pollution in urban water systems, Hydrology and Water Quality Research Group at Integrated Laboratory Universitas Tanjungpura planned a 3-year research. The first activities are aims to test the sampling method and at the same time obtain information about microplastic in the water canal of Pontianak. Samples were taken at five canals that passes through different urban land uses: housing, small and home industries, and business; using a modified version of manta trawler. Results show the abundance of microplastic in the canals are between 348 x 102 to 533 x 102 particle/m3 of water. The majority forms are fragments, fibers, pellets, and films with the amount of each type in 1 liter (0,001 m3) of water sample are 984, 679, 203, and 110 particles, respectively. The results of this research can increase understanding of the threat of microplastic and useful for other cities on the coastal region of Kalimantan, which habitually have a culture that is closely related to rivers and canals.

Keywords: Microplastic pollution, microplastic abundance, urban water system, Pontianak, Manta Trawl.

Introduction

Indonesia is the second-largest country in the world after China as a producer of plastic waste that ends up in the sea (Jambeck et al. 2015). Most of the plastic waste in the ocean comes from the land through rivers and city drains. With the large amount of plastic waste produced, the risk of environmental damage due to plastic waste can be a time bomb that can endanger the river ecosystem. Plastics contain toxic monomers and addictive substances such as bisphenol A and phthalates which can dissolve into seawater and affect aquatic organisms (Mohamed Nor and Obbard 2014). Due to ultraviolet radiation, waves, and currents, plastic polymers in water bodies can be broken down into smaller plastic fragments. Larger plastics also degrade into smaller fragments through photodegradation and other weathering processes. According to the size of the plastic particles, the fine particles of plastic waste can be referred to as microplastics and nanoplastics. Microplastics are plastic particles with a size of less than 5 mm, divided into two categories, namely large (1-5 mm) and small (<1 mm) (NOAA, 2015).

Sources of microplastics are divided into primary and secondary sources. Primary microplastics are pure plastic particles that reach marine areas due to careless handling. Primary microplastics are plastics that are directly released into the environment in the form of small particles. These plastics come from products containing plastic particles (such as tiny droplets in shower gel), and can also come from the degradation of large plastic objects in manufacturing, use, or maintenance processes such as tire erosion or degradation of synthetic textiles during washing. Secondary microplastics come from macroplastic degradation processes that can occur due to sunlight, currents, and waves in the marine environment. (Eriksen et al. 2014). Since sunlight exposure, water currents and waves do not only occur in the sea but can also occur in other type of water bodies, secondary microplastic can be also formed in the rivers and channels.

Microplastics are very small in size, and their abundance in rivers makes them ubiquitous and highly bioavailable to aquatic organisms. So that microplastics can be eaten by marine biota (Andrady 2011). The plastic fragments that are formed will cause the possibility of these fine particles entering the food chain, thus endangering human health. There are 61 ditches in the city of Pontianak, which are connected to the sea via Kapuas River, can be a pathway for plastic to enter the sea. Kapuas River itself, which is run through te city, is the longest and one of the most important river in Pontianak. People still use the river as the main source of water for their daily needs, as well as Pontianak Drinking Water Company which also uses it as the main source of its bulk water.

Many types of research on microplastics have been carried out in big cities around Indonesia, with research locations in estuaries or the sea. However, research conducted in small and medium-sized cities is still relatively rare. In addition, research locations in urban drainage are also still rarely done. As is well known, urban drainage is the first container to receive wastewater from several sectors in urban areas, such as settlements, schools, hospitals, markets, and also businesses such as laundry. After that, the water in the drainages will flow out towards the mouth of the river to the sea. Therefore, this study was conducted to determine the abundance of microplastics in urban canals in Pontianak City, before leaving to the Kapuas river estuary. The number of sampling point locations was taken as many as 5 different locations representing several sectors in Pontianak City such as settlements, hotels, markets, and business units such as laundry. The sample taken is a sample of surface water trapped in the net attached to a specialy designed equipment. Then, the sample can be directly processed in the laboratory to obtain the number and abundance of microplastic particles.

To determine which channels and rivers in polluted, we can use the abundance of microplastic. Therefore, this research will be focusing on measuring the abundance of microplastic using multiple methods. The abundance of microplastic also shows that there is plastic pollution in the channel and will end up in the Kapuas River that flows through the city of Pontianak. It is hoped that with the presence of this research, the public will know that these microplastic pollutants are very easy to find around them, including in some of the daily necessities they use. In addition, so that people can be wiser in using and processing the waste produced, especially plastic waste.

Research Method

In this study, the sampling method was used to obtain samples of microplastics from drainage channels. Microplastic samples are then processed in the laboratory to achieve research objectives. Sampling was carried out purposively at each depth of channels from the sampling location. In addition to the sampling activities, measurement of channels cross-sectional area, water pH and temperature, and current velocity in the channels were also carried out. The processing method for microplastic sample is refers to the NOAA method sourced from Masura et al, 2015. The method in principle does the following: separating/floating plastics, destroying organic matter using hydrogen peroxide, and filtering. After processing, the samples were observed under a microscope to obtain type, color, and number of microplastic particles present in the sample.

The data analysis in this study uses qualitative and descriptive method which describes type, color, and the abundance of microplastics as particles/m3 in each sample.

Data were collected in five locations around Pontianak City, namely Sungai Raya Dalam (T1), Parit Haji Husin (T2), Parit Sepakat (T3), Parit Media (T4), and Parit Martapura/Tokaya (T5).


[Figure 1 Sampling Location Map]

Sample processing includes several stages, namely: sample preparation, sample separation, and sample identification. Some of these steps are international procedures carried out by (Masura et al., 2015). Sample preparation is done by preparing samples, making work logs, and preparing materials and tools needed for the next process. Separation of samples using a graduated sieve smaller than 30 mm was used to separate meso and micro waste. The filter results obtained are then treated by adding chemicals to separate organic matter and increase density. After being treated, the sample can be observed visually under a microscope. This guide to the identification of microplastics is based on research conducted by Masura et al, on Laboratory Methods for the Analysis of Microplastics in the Marine Environment: Recommendations for quantifying synthetic particles in waters and sediments.

Results

Surface water samples were taken using a with a very fine sized net. The aim was to obtain microplastic particles either from the primary sources or resulting from the degradation of macroplastic in the water. After going through several treatment processes for the samples as described in the working procedure, the microplasctic in each sample were found as follows.


Table 1. Number of Microplastic Particles

No	Sampling location	Microplastic Particles Form
		Fiber	Fragment	Film	Foam	Pellet(Bead)	Total Number of Microplastic Particles
1	Parit Sungai Raya Dalam (T1)	150	232	0	43	13		438
2	Parit Haji Husin 1 (T2)	152	169	12	2	13	348
3	Parit Sepakat (T3)	81	239	13	8	12	353
4	Parit Media (T4)	189	76	28	0	68	361
5	Parit Martapura (Tokaya) (T5)	107	268	150	4	4	533

Source: Data Analysis, 2021



[Figure 4 Total of microplastic particles]

The abundance of microplastics can be calculated by comparing the number of particles found with the volume of filtered water (Masura et al, 2015) as shown in the following formula. Abundance of microplastics= Number of microplastic particles(particle)…………….......(1)

Filtered water volume (m3)

The abundance of microplastic calculated using the formula is as presented in Table 2.
Table 2. Microplastic Abundance in 1 m3 surface water samples

No	Sampling location	The abundance of microplastics (particle/m3)
1	Parit Sungai Raya Dalam (T1)	438x10²
2	Parit Haji Husin 1 (T2)	348x10²
3	Parit Sepakat (T3)	353x10²
4	Parit Media (T4)	361x10²
5	Parit Martapura (Tokaya) (T5)	533x10²

Discussion

This study focuses on the presence of microplastics in the drainage channel of Pontianak. These channels accommodate wastewater flowing from settlements or other sectors. This research was conducted by taking samples of surface water from 5 different drainages channels in Pontianak City.

In Table 1, it can be seen that the number of microplastic particles found in drainage channel in Pontianak varied from 348 to 533 particles. As for the first location T1, represents residential area in Pontianak. The residential area is already filled with houses, where from every house there is a sewerage that connected to Sungai Raya Dalam channels and will empty into the Kapuas River.

Trading activities such as small industries and shops can also be found in this location. Therefore, this location is used as an example of a sampling location that can represent activities that cause pollution, especially in waterways and rivers. The existing conditions at the sampling location were that there was a lot of floating wood and the weather at the time of sampling was sunny. In Table 2, the results of the abundance of microplastics obtained at location T1 are 438 x 10² particles/m³.

The second location is Parit Haji Husin with location code T2 representing the vegetated settlement sector and green open space. This location has a lot of housing and is balanced with vegetation that grows around people's homes. The findings of the abundance of microplastics at this location can be seen in Table 2, which is 348 x 10² particles/m³.

The next location is in Parit Sepakat with code T3. The agreed ditch is drainage that accommodates processed water in the agreed area where this area is dominated by the laundry sector, lodging, restaurants, and campus dormitories. Existing conditions that affect the sampling area are the sampling locations near the cemetery with slightly cloudy weather on the day of sampling. At that location, the number of microplastic particles found was 353 x 10² particles/m³.
Parit Media is the next location coded T4. At that location, the number of particles found was 361 x 10² particles/m³. The dominant form of microplastic in this location is fiber. As we all know, hotels have laundry facilities in each hotel with a fairly large washing capacity considering the many washing needs in the hotel. Therefore, the most common form of fiber is found in that location. This fiber comes from clothing fibers that are also exposed to the sewer/drainage.

The last location is in Parit Martapura/Tokaya. At this location, the number of microplastics was found to be 533 x 10² particles/m³. The majority of microplastic forms are dominated by fragments, but there are quite a lot of film forms at location T5. A film is a form of microplastic that resembles thin plastic sheets or lumps with several colors but is generally found in transparent colors.

This form of the film can be found at location T5 because in that location there is a large market that sells basic needs such as fish, chicken, meat, vegetables, and others. The use of plastic in the market is very uncontrolled. In addition, there is also a speed boat stop and captivity so that the detected forms of microplastics can come from these places. The number of particles found at the T5 location is the largest number among other microplastic particles. It can be said that there is a relationship between the number of microplastics and the number of sources or industries in the location.

Conclusion

Based on the results, it can be concluded that the majority types of microplastics particles found in the urban drains of Pontianak from all sampling locations are Fiber, Fragment, Film, Foam and Pellet. The highest number of microplastic particles found at the Parit Tokaya (T5) with an abundance of 533 x 102 particles/m3. The average number of microplastics is 407 microplastic particles in the urban drains of Pontianak city.

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