Beach Litter - Median number of cigarette related items normalized per 100m & to 1 survey - UNEP_MARLIN only - Other sources 2012/2014 v2021

This visualization product displays the cigarette related items abundance of marine macro-litter (> 2.5cm) per beach per year from non-MSFD monitoring surveys, research & cleaning operations related to UNEP-MARLIN data only. EMODnet Chemistry included the collection 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: - Selection of surveys from non-MSFD monitoring, cleaning and research operations; - Exclusion of beaches without coordinates; - Selection of cigarette related items only. The list of selected items is attached to this metadata. This list was created using EU Marine Beach Litter Baselines and EU Threshold Value for Macro Litter on Coastlines from JRC (these two documents are attached to this metadata); - Exclusion of surveys without associated length; - Selection of surveys referring to the UNEP-MARLIN list: the UNEP-MARLIN protocol differs from the other types of monitoring in that cigarette butts are surveyed in a 10m square. To avoid comparing abundances from very different protocols, the choice has been made to distinguish in two maps the cigarette related items results associated with the UNEP-MARLIN list from the others; - Normalization of survey lengths to 100m & 1 survey / year: in some case, the survey length was not 100m, so in order to be able to compare the abundance of litter from different beaches a normalization is applied using this formula: Number of cigarette related items of the survey (normalized by 100 m) = Number of cigarette related items of the survey x (100 / survey length) Then, this normalized number of cigarette related items is summed to obtain the total normalized number of cigarette related items for each survey. Finally, the median abundance of cigarette related items for each beach and year is calculated from these normalized abundances of cigarette related items per survey. Percentiles 50, 75, 95 & 99 have been calculated taking into account cigarette related items from other sources data (UNEP-MARLIN protocol only) for all years. More information is available in the attached documents. Warning: the absence of data on the map doesn't necessarily mean that they don't exist, but that no information has been entered in the Marine Litter Database for this area.

本可视化产品仅展示基于联合国环境规划署-马林计划（UNEP-MARLIN）相关的非海洋战略框架指令（Marine Strategy Framework Directive, MSFD）监测调查、研究与清理行动所获取的数据，统计每处海滩每年的海洋大型垃圾（粒径＞2.5cm）中与卷烟相关物品的丰度。
欧洲海洋观测与数据网化学分部（EMODnet Chemistry）已将海洋垃圾收集纳入其第三阶段工作范畴。自2018年初起，海滩垃圾数据已在该分部的海洋垃圾数据库（Marine Litter Database, MLDB）中完成收集与处理。
鉴于欧洲范围内数据源、采样方案及参考名录存在异质性，对所有数据进行统一协调是本次工作中最具挑战性的任务。为完成全量数据的统一协调，需开展如下预处理工作：
- 筛选非MSFD监测、清理及研究行动相关的调查数据；
- 剔除无坐标信息的海滩相关数据；
- 仅保留与卷烟相关的垃圾条目。本次筛选的垃圾条目清单已附于本元数据中，该清单依据欧盟联合研究中心（Joint Research Centre, JRC）发布的《欧盟海滩垃圾基线》及《海岸线大型垃圾欧盟阈值标准》制定（上述两份文档均附于本元数据）；
- 剔除未附带调查长度信息的调查数据；
- 筛选采用UNEP-MARLIN名录的调查数据：UNEP-MARLIN采样方案与其他监测类型的区别在于，其采用10平方米样方对烟蒂进行调查。为避免对比不同采样方案下得到的垃圾丰度结果，本次将分别通过两张地图展示关联UNEP-MARLIN名录与其他来源的卷烟相关物品丰度数据；
- 将调查长度标准化为100米，并按每年1次调查进行归一化处理：部分调查的实际采样长度并非100米，为实现不同海滩垃圾丰度的可比分析，需通过以下公式完成标准化：标准化后每100米样带的卷烟相关物品数量 = 原始调查得到的卷烟相关物品数量 × (100 / 调查实际长度)
随后，将该标准化后的卷烟相关物品数量求和，得到单次调查的总标准化卷烟相关物品数量。最终，基于单次调查得到的标准化丰度数据，计算得到每处海滩每年的卷烟相关物品丰度中位数。针对所有年份的非UNEP-MARLIN名录来源的卷烟相关物品数据，已计算得到50、75、95及99百分位数值。
更多细节可参阅随附文档。
注意：地图上无数据并不代表该区域不存在海洋垃圾，仅代表该区域尚未有数据录入海洋垃圾数据库。