A 75-year history of microplastic fragment accumulation rates in a semi-enclosed hypoxic basin
A 75-year history of microplastic fragment accumulation rates in a semi-enclosed hypoxic basin
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半封闭缺氧盆地微塑料碎片累积率 75 年历史
DOI：
10.1016/j.scitotenv.2022.158751
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发表时间：
2023
影响因子：
9.8
通讯作者：
Suzuki Yoshiaki
中科院分区：
文献类型：
--
作者：
Hinata Hirofumi;Kuwae Michinobu;Tsugeki Narumi;Masumoto Issei;Tani Yukinori;Hatada Yoshio;Kawamata Hayato;Mase Atsuomi;Kasamo Kenki;Sukenaga Kazuya;Suzuki Yoshiaki
海洋环境中的塑料预算及其长期趋势尚未得到充分了解。测量海底沉积物中的堆积率对于解开失踪海洋塑料之谜至关重要。以前基于沿海沉积物岩心的研究发现，随着塑料产量和/或区域人口的增加，积累率也随之增加。然而，对微塑性下沉过程建模至关重要的生物活动或海洋动力学与速率之间的相关性尚未得到检验。根据沉积物的多岩心分析和210Pb测年，揭示了日本别浦湾一个缺氧盆地75年来微塑性碎片(0.3-5.0 mm)的累积速率历史，并与137Cs放射性峰值进行了时间控制交叉验证。我们发现，在1958.8-1961.0 CE的沉积层中发现了第一个聚丙烯微塑性碎片，这是一个长期的线性增长趋势，变化约20年，与1990年和2014年前后的显著峰值重叠。2014年，−2y−1的最高速度为203条，−1-Dry的数量为86条。在整个1955-2015年期间，0.3-2.0 mm尺寸范围内的较小碎片在累积速率方面一直占据主导地位，占总累积速率的85.3%。三大聚合物(聚乙烯、聚丙烯和聚苯乙烯)占总比率的96.6%。这一速率与沉积物中叶绿素a的积累速率和浓度呈高度正相关。根据微塑料在海水中的积累速率和浓度，估算出微塑料的平均下沉速度约为101m d−1。我们的结果将有助于在模拟微塑料下沉过程方面取得重大进展，因为我们的结果提供了第一个基于现场测量的平均下沉速度以及该速度与生物活性相关信号之间的显著相关性。
Plastic budgets in the marine environment and their long-term trends are yet to be fully understood. Measuring the accumulation rates in bottom sediments is crucial to solving the riddle of missing ocean plastics. Previous studies based on coastal sediment cores have found that accumulation rates have increased with increases in plastic production and/or regional populations. However, the correlations between the rates and bioactivities or ocean dynamics, which are crucial for modeling the microplastic sinking process, have not been examined. We revealed a 75-year microplastic fragment (0.3–5.0 mm) accumulation rate history in a hypoxic basin, Beppu Bay, Japan, based on multi-core analysis and210Pb dating of the sediment which was cross-checked by time control with137Cs radioactivity peaks. We found that a long-term linear increasing trend with an approximately 20-year variation overlapped with significant peaks around 1990 and 2014 with the first polypropylene microplastic fragment detected from a 1958.8–1961.0 CE sediment layer. The maximum rate was 203 pieces m−2y−1with an abundance of 86 pieces kg−1-dry in 2014. Smaller fragments in the size range of 0.3–2.0 mm have been consistently dominant in terms of the accumulation rate throughout the 1955–2015 period, accounting for 85.3 % of the total accumulation rate. The three major polymers (polyethylene, polypropylene, and polystyrene) accounted for 96.6 % of the total rate. The rate was highly and positively correlated with the chlorophyll-aaccumulation rate and concentration in the sediment. Based on the microplastic accumulation rates and concentration in the seawater, the mean sinking velocity of microplastics was estimated to be in the order of 101m d−1. Our results will contribute to significant progress in modeling the microplastic sinking process by offering the first field measurement-based mean sinking velocity and significant correlations between the rate and bioactivity-related signals.