Riverine floating macrolitter: the Italian national monitoring programme within the Marine Strategy
Most marine litter originates on land, disperses into the environment, and is transported via rivers into the seas. As part of the monitoring programs under the Marine Strategy Directive, which provides a framework for community action in marine environmental policy, an Operational Agreement between the Ministry of the Environment (MASE) and ISPRA included a monitoring program on floating macro-litter in 12 Italian rivers at survey stations near their mouths.
The aim of the monitoring program was to verify the quantity and quality of riverine litter input to the marine environment, using a Source to Sea approach. Monitoring floating macro-litter in rivers is crucial as it serves as an indicator of both waste dispersed in the environment and the effectiveness of measures aimed at reducing waste production and dispersion.
The first year of monitoring highlighted that the Tiber, Sarno, and Po rivers are the waterways, among those monitored, that convey most macro-litter into the sea. Rivers passing through densely populated urban centers carry more litter than those in rural areas or with low flow rates. Over 80% of the riverine litter is plastic, with a third being single-use items. Most objects are small (<10cm) indeterminate fragments; among identifiable items, the largest percentage comes from food consumption and packaging.
To understand the dynamics of macro-litter floating in rivers and their relationship with flow rates, floating containers designed to simulate the performance of macro-litter were released into the rivers with GPS trackers. Tracking their positions highlighted the long permanence of objects in the river and a recurring “stop & go” pattern in relation to higher flows. Among the trackers that reached the sea, many travelled several kilometres before beaching and being subsequently recovered. Their journey, both in the river and at sea, provided useful information for waste management policies, at local, national and cross-border level.
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