The Occurrence of Microplastics in Sediment Cores from Two Mangrove Areas in Southern Thailand

Siriporn Pradit,Che Abd Rahim Mohamed,Thi Phuong Quynh Le,Choon Weng Lee,Jianjun Wang,Chantha Oeurng,Thongchai Nitiratsuwan,Gusti Z Anshari,Xixi Lu,Pei-Sun Loh,Prakrit Noppradit,Selvaraj Kandasamy

doi:10.3390/jmse10030418

Abstract

Mangroves are areas that connect the land and sea, and are important to the ecosystem. They are important places for food sources and the habitat of aquatic fauna in the tidal areas. However, the existence of plastic debris poses a risk to the aquatic environment. This study aimed to investigate the accumulation of microplastics (MPs) in sediment cores from two mangrove areas. The first mangrove area is in the outer section of the Songkhla lagoon (SK), while the second is in the coastal area of Pattani province (PN). Sediment core sampling was performed from SK = 8 stations and PN = 5 stations. Surface enrichment of MP was observed, especially in sediments of 0–4 cm. MPs were found throughout the depth in both areas, while fewer MPs were found in deeper sediment core layers (p < 0.05) at some stations inside the mangrove zone. Simple linear regression of the observed MPs and distance in the horizontal were found to be significant at SK within the mangrove zone with r2 = 0.79 (p < 0.05). MP fibers were the most commonly found MP type in both areas and were less than 1 mm. Blue and black MPs were the most abundant colors found in both areas. The six polymer types reported in this study comprised polyethylene, rayon, rubber, styrene, Poly (vinyl acetate), and paint. The findings of the present study suggest that long-term monitoring of marine debris along coastlines is necessary to help improve national policies and measures related to marine plastic debris.

Highlights

Over recent decades, plastic pollution has become a global environmental concern due to increased plastic production and consumption
The first mangrove area is at the outer section of Songkhla Lagoon (SK), Thailand (Figure 1), which is situated in southern Thailand and is connected to the Gulf of Thailand through The first mangrove area is at the outer section of Songkhla Lagoon (SK), Thailand (Figure 1), a narrow strait
A decreasing trend in depth was observed at Songkhla lagoon (SK), except for at SK08, which is located outside the mangrove area and resulted in amounts of MPs similar to all depths

Summary

Introduction

Plastic pollution has become a global environmental concern due to increased plastic production and consumption. MPs are fragments of any plastic particles less than 5 mm in size [5] They can be categorized based on their shape, size, color, and raw material. They are generally found in different shapes such as film, fragments, pellets, and fibers [6], which disperse into the environment. They are difficult to degrade and pose a long-term threat to marine ecosystems. Plastic contamination in the ocean is a global concern due to its negative effects on marine health and biota. Previous studies indicate that MPs can adsorb persistent organic pollutants (e.g., polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and DDT) and heavy metals (e.g., cadmium, mercury, and chromium), which could be transferred to higher trophic levels [11–13]

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