Microplastic pollution has been reported from coral reef systems all over the tropics. Exposure to microplastics has several negative impacts on coral health, such as bleaching, tissue necrosis, or an impairment of the coral’s immune system. Despite this potential risk for reef systems, the controlling processes for microplastics dispersion and accumulation in reef sediments are still largely under-studied. Presented here is a study of microplastics (125 µm to 5 mm) distribution in two tropic atoll reef platforms in Kepulauan Seribu, Indonesia. Sediment samples were collected in different facies zones within the reef platform. Microplastics were concentrated using density floatation and characterized by light and scanning electron microscopy. Some particles were identified as polypropylene using micro-Fourier transform infrared spectroscopy. All recovered microplastics were classified as secondary microplastics, likely derived from marine and local sources, with fibres as the most abundant type. Microplastics are showing similar transport and accumulation behaviour as fine siliciclastic grains. The abundance of microplastic is controlled by the proximity to the source area of larger plastic debris and hydrodynamic processes. Microplastics are not only present in low energy environments but also high energy settings such as the reef crest. Processes that contribute to accumulation in reef sediments are biofouling, interlocking and the creation of compound grains. Microplastics are present in sediment close to the seafloor (0 to 3.5 cm) but also at depths between 3.5 cm and 7.0 cm. Microplastic particles from below 3.5 cm are unlikely to be remobilized under modal weather conditions in the studied equatorial reefs. Subtidal reef sediment therefore can be regarded as a permanent sink for microplastics. The study shows that microplastics in coral reef environments deserve careful consideration since microplastics pose an additional threat to corals and their ability as framework builders in reef systems.

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微塑料作为珊瑚礁系统中的沉积成分：爪哇海的案例研究

据报道，整个热带地区的珊瑚礁系统都存在微塑料污染。接触微塑料会对珊瑚健康产生多种负面影响，例如漂白、组织坏死或珊瑚免疫系统受损。尽管珊瑚礁系统存在这种潜在风险，但对珊瑚礁沉积物中微塑料分散和积累的控制过程仍然缺乏研究。这里介绍的是对印度尼西亚 Kepulauan Seribu 的两个热带环礁平台中微塑料（125 µm 至 5 mm）分布的研究。在珊瑚礁平台内的不同相带收集沉积物样品。使用密度浮选浓缩微塑料，并通过光学和扫描电子显微镜进行表征。使用微傅立叶变换红外光谱法将一些颗粒鉴定为聚丙烯。所有回收的微塑料都被归类为二次微塑料，可能来自海洋和当地来源，其中纤维是最丰富的类型。微塑料显示出与细硅碎屑颗粒相似的传输和积累行为。微塑料的丰度受到靠近较大塑料碎片源区和流体动力学过程的控制。微塑料不仅存在于低能量环境中，还存在于礁顶等高能量环境中。导致珊瑚礁沉积物堆积的过程是生物污垢、互锁和复合颗粒的产生。微塑料存在于靠近海底（0 至 3.5 厘米）的沉积物中，但也存在于 3.5 至 7.0 厘米的深度。3.以下的微塑料颗粒。在所研究的赤道珊瑚礁中，在模态天气条件下不太可能重新动员 5 厘米。因此，潮下礁沉积物可被视为微塑料的永久汇。该研究表明，珊瑚礁环境中的微塑料值得仔细考虑，因为微塑料对珊瑚及其作为珊瑚礁系统框架构建者的能力构成了额外的威胁。