Microplastic Contaminants in the Sediment of the East Coast of Saudi Arabia

*Hamza Jawad Al-Shaikh Ali, Assad Ahmed Al-Thukair, Abdurahiman Kambrath Pulikkoden and Basheer Chanbasha*

### **Abstract**

Microplastic contamination in the sediment of the east coast of Saudi Arabia was not addressed by any study. The objective of this study is to obtain the first measurement of microplastic abundance at four different beaches on the east coast of Saudi Arabia (Khafji, Jubial, Dammam, and Salwa). Sediment samples were collected from both high tide and low tide zone. A total of 586 microplastic particles were collected from all the sites with an average particle size of 1.55 ± 0.94 mm. The majority of microplastic particles (77%) were less than 2 mm in size. Microplastic abundance ranged from 5.5 ± 1.55 to 21.2 ± 0.68 particle/kg (51.1 ± 14.71 to 152.8 ± 21.32 particle/m2 ) in low tide region, and from 6.3 ± 4.05 to 16.5 ± 4.98 particle/kg (50.6 ± 31.21 to 204.5 ± 64.15 particle/m2 ) in high tide region. The most dominant colors were transparent (34%) and blue (30%), while the fiber was the most common shape (96%). Polyethylene terephthalates were the common polymer type of fibers, while polyethylene and high-density polyethylene were common in fragments and filaments.

**Keywords:** microplastic, marine contamination, sediments, Arabian Gulf, microplastic contaminants

### **1. Introduction**

The plastic production rate is increasing exponentially since the 1950s reaching more than 400 million tons per year in 2020 [1]. People favor plastic over other materials mainly because of its properties, such as durability, lightweight, and flexibility. A study done by Ritchie and Roser in 2018 estimated that the total plastic floating on the global ocean surface is about 269,000 [2]. Plastic polymers are often combined with an additive, which includes chemical compounds, metals, or persistent organic pollutants (POP) [3–5]. Some of these additives are significantly toxic to humans if ingested, inhaled, or even during dermal contact [6]. Plastic litter can degrade or break into smaller micro-size plastic via various routes, such as mechanical forces, UV light from the sun, biological degradation, oxidation, or hydrolysis [7–9].

Microplastics are defined as synthetic polymer particles, that is, less than 5 mm in diameter. The first identification of microplastic was done in 1972 by carpenter et al. in the Sargasso Sea in plankton net trawls [10]. Microplastic is introduced to the marine environment either as primary or secondary microplastic. Primary microplastics are plastic particles that are manufactured to be less than 5 mm in size. Secondary microplastics are created by the fragmentation of large plastic products into smaller particles [11]. Microplastic is usually introduced to the marine environment through wastewater, surface runoff, or fragmentation of plastic products in landfill and coastal areas [11].

Microplastic pollution is measured in water, sediments, and organisms. In marine environments, beaches are considered to be the reservoir of macroplastic and microplastic debris [12]. They receive plastic pollution from land and transport it to coastal water, and then open ocean. However, the fate of microplastic spatial distribution is uncertain and it depends on several factors: (1) chemical structure of microplastic, (2) seawater density, (3) weather, (4) microplastic additives, (5) polymer type, (6) ecological impact, and (7) fragmentation ability [13, 14]. Rivers are also considered a major source of microplastic contamination in the marine environment, and this is because they usually pass through several urban areas before discharging into the ocean [15].

Microplastics can interact with marine organisms mainly through ingestion due to their small size similar to organisms' natural food. Several studies were done to measure microplastic contamination and risk in microorganisms [10, 16, 17], fish and mammals [18–21], and birds [22]. It was found by scientists that biota exposed to microplastic will have negative health effects, such as decreasing food consumption [23], decrease in weight [24], growth rate [25], and fertility [26]. In the aquatic environment, bivalves are the most commonly used organism in the labs for exposure studies [27]. Also, because of their filter-feeding behavior, bivalves are used in several studies as a bioindicator for microplastic contamination [28].

### **2. Study area**

Arabian Gulf is an important sea to the surrounding countries due to the existence of huge oil and gas reservoirs, supplying the countries with domestic water through desalination plants, and because of its richness in a variety of biological resources that supply the countries. Saudi Arabia has a coastline of around 800 km long on the Arabian Gulf starting from Khafji and ending in Salwa Bay [29]. The kingdom's territorial water covers an area of 27,050 km2 , which is more than 10% of the total Arabian Gulf area (240,000 km2 ) [30]. Arabian Gulf is considered one of the most stressful environments for marine organisms due to its high salinity caused by the high temperate and low precipitation rate [29]. The gulf is a semi-enclosed sea surrounded by arid lands in the west and the Zagros mountains in the east and connected to the Indian Ocean through the Straits of Hormuz. The average depth of the gulf is 35 m and reaches a maximum depth of 100 m near the Straits of Hormuz [29]. The circulation in the Arabian Gulf is counterclockwise mainly driven by wind, and thermohaline [29]. A model of the gulf was created by Yousef Alosairi et al. [31] using a three-dimensional numerical model estuary, lake and coastal ocean model (ELCOM) which shows that the flushing time along the Arabian coast is more than 3 years, a slow process compared to other seas. The Arabian Gulf is surrounded by eight developing countries, including Saudi Arabia, Bahrain, Qatar, United Arab Emirates, Oman, Kuwait, Iraq, and Iran. Each of these countries has several cities and projects along the Arabian Gulf coastline, such as desalination plants, treated sewage disposal, nuclear plants, and many oil and gas production industries.

Only 17 published studies related to microplastic were done in the Arabian Gulf in which most of which are on Iranian coasts and the Strait of Hormuz. Therefore,

*Microplastic Contaminants in the Sediment of the East Coast of Saudi Arabia DOI: http://dx.doi.org/10.5772/intechopen.109019*

**Figure 1.** *Location of the four different beaches on Saudi Arabia's east coast.*

the objective of this study is to characterize and compare microplastic contamination in the sediment at Saudi Arabia's east coast at four different beaches (Khafji, Jubail, Dammam, and Salwa Bay) (**Figure 1**). By measuring the following parameters:

