[NAT] North Sea trend of number of garbage parts on the beach

Download service for national data for the Marine Strategy Framework Directive reporting obligation 2018. Subject: Trend of number of garbage parts on the beach (North Sea)面向2018年《海洋战略框架指令（Marine Strategy Framework Directive）》报告义务所需国家数据的下载服务。主题：北海海滩垃圾碎片数量变化趋势。