Beach Litter - Mean number of Plastic bags related items per 100m & to 1 survey - Other sources

This visualization product displays plastic bags abundance per beach per year obtained during research & cleaning operations. EMODnet Chemistry included the gathering of marine litter in its 3rd phase. Since the beginning of 2018, data of beach litter have been gathered and processed in the EMODnet Chemistry Marine Litter Database (MLDB). The harmonization of all the data has been the most challenging task considering the heterogeneity of the data sources, sampling protocols and reference lists used on a European scale. Preliminary processing were necessary to harmonize all the data : - Exclusion of OSPAR 1000 protocol, - Separation of monitoring surveys from research & cleaning operations - Exclusion of beaches with no coordinates - Normalization of survey lengths and survey numbers per year - Some categories & some litter types have been removed Abundances have been calculated on each beach and year using the following computation: Plastic bags abundance=(total number of plastic bags (normalized at 100m))/(Number of surveys on the year) Percentiles 50, 75 & 95 have been calculated taking into account data from all years. Plastic bags reference codes taken into account for this product and information on data processing (some normalization have been necessary) and calculation are detailed in the document attached p15.

本可视化产品展示了每年在海滩清理与研究活动中收集到的塑料袋丰度数据。EMODnet Chemistry 在其第三阶段工作中纳入了海洋垃圾的收集。自2018年初起，海滩垃圾数据便开始在 EMODnet Chemistry 海洋垃圾数据库（MLDB）中进行收集与处理。鉴于数据来源、采样协议及在欧洲范围内使用的参考列表的异质性，数据的协调一致成为最具挑战性的任务。为了实现数据的协调一致，进行了初步的处理工作：- 排除 OSPAR 1000 协议，- 将监测调查与研究及清理活动分开，- 排除无坐标的海滩，- 规范化每年的调查长度及调查次数，- 删除了一些类别及某些垃圾类型。在每个海滩和每年的基础上，根据以下计算方法计算塑料袋丰度：塑料袋丰度=（塑料袋总数（按100米规范化））/（当年的调查次数）。计算了考虑所有年份数据的第50、第75和第95百分位数。本产品所考虑的塑料袋参考代码及数据处理信息（某些规范化为必要）和计算方法详见所附文档第15页。