DOI: 10.4121/77d424f5-fad5-44a8-91d6-01a29d161784
title: Dataset: Floating plastic transport and accumulation in Amsterdam 2022-2023

description: This dataset contains data from monthly plastic monitoring efforts at twenty locations in Amsterdam between November 2022 and October 2023. The ArcGIS Survey123 application (ESRI, Redlands, California) with a customized form was used to efficiently log the observed floating plastic items in digital forms. Items at all locations were categorized using the River-OSPAR protocol, originally developed by the North Sea Foundation [1]. Two types of monitoring took place. <br>First, accumulated items were monitored at eleven locations, counting and categorizing all floating items within the most polluted 100 square meters of surface area. This area can be variable depending on the conditions during the measurement day. Additionally, the surface area does not follow any geometry rules, i.e. it can have any shape or form. We determined the monitored area by drawing polygons in Google Earth and redefined this area to capture the most polluted surface when deviating from the original surface area (Example: Figure 1a and b). <br>Second, the transport of items was monitored at nine locations, using the visual counting method to estimate plastic transport [2]. The observer counts and categorizes all floating items for a predetermined time interval and observation width on top of a bridge. Each bridge was divided into 1 to 3 segments, depending on the length of the bridge. Segments can be unequal in width by covering the distance between bridge pillars (Example: Figure 1c). Consequently, each segment covers a part of the waterway within the field of view of the observer, enabling the identification of all floating items within a given segment. Here, every segment was measured four times for five minutes every monitoring round. <br>The dataset contains one main file, 'dataset.xlsx' with six sheets:<br>1) Locations + metadata | Description of the monitored locations with identifiers, street names, type of monitoring and lat/lon coordinates<br>2) Transport (flux) data | All entries of monitored items for transport locations.<br>3) Accumulation (density) data | All entries of monitored items for accumulation locations.<br>4) Totals and top ten items | Total counts per item category, an overview of the categories and share of top ten items both summed for all locations and per location. 5) Transport calculations into IJ | Stepwise calculations from raw data to mass transport estimates in [kg/yr] into the IJ river. A short description of all calculation steps is included in this sheet. <br>6) Mass calculations for accumulation and transport, for each item category with all locations combined.<br>For sheet 2 and 3, all timestamps are in UTC. To convert to local time, the purple timestamps are UTC+1 (CET), and the green timestamps UTC+2 (CEST).<br>The dataset contains one figure, providing an example of monitoring. Figure caption: a) Top view of `accumulation' monitoring area at location NW2, (b) side-view with the same monitoring area, (c) top view of `transport' monitoring at location O1B. This bridge is divided into three segments (S1, S2, S3) which can be monitored by one or multiple observers simultaneously.<br>