Variance and precision of microplastic sampling in urban rivers.
Variance and precision of microplastic sampling in urban rivers.
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DOI：
10.2139/ssrn.4068339
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发表时间：
2022-08
影响因子：
8.9
通讯作者：
Mamoru Tanaka;T. Kataoka;Y. Nihei
中科院分区：
文献类型：
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作者：
Mamoru Tanaka;T. Kataoka;Y. Nihei
微塑料 (MP)，即直径 <5 毫米的塑料颗粒，已成为环境中普遍存在的新兴问题。河流是将国会议员从陆地运送到海洋的主要通道；然而，淡水环境中原位采样的标准化方法仍未确定。值得注意的是，MP 采样方法的不确定性会导致河流 MP 排放量的估算出现错误。在本研究中，调查了日本两条城市河流浮游生物净获得的 MP 浓度的样本间方差。以粒子·m-3 表示的数值浓度表明，方差 s2 与数值浓度的重复估计值的平均值 m 成正比。推导的统计模型表明，河流 MP 的分散是完全随机的过程；即泊松点过程。因此，建立了一种方法来预测基于净采样重复次数的数值浓度的“精度”，即标准误差与 m 的比率。结果发现，对于≥3颗粒·m-3的高浓度条件，两次重复的平均值保持了<30%的足够精度。还提供了不同 MP 浓度水平下的预计精度，以帮助设计未来的现场活动。
Microplastics (MPs), plastic particles <5 mm in diameter, have become an emerging ubiquitous concern for the environment. Rivers are the primary pathways that transport MPs from the land to the ocean; however, standardized methodologies for in-situ sampling in freshwater environments remain undefined. Notably, uncertainties in MP sampling methods lead to errors in estimating MP discharge through rivers. In the present study, the inter-sample variance of plankton net-obtained MP concentrations for two urban rivers in Japan was investigated. Numerical concentrations, expressed in particles·m-3, revealed that variance s2 was proportional to the mean m of replicated estimates of numerical concentrations. A derived statistical model suggested that river MPs disperse according to purely random processes; that is, Poisson point processes. Accordingly, a method was established to project the "precision," the ratio of the standard error to m, of numerical concentrations based on the number of net sampling repetitions. It was found that the mean of two replicates maintained sufficient precision of <30% for conditions with high concentrations of ≥3 particles·m-3. Projected precisions under different levels of MP concentrations are also presented to help design future field campaigns.