A high percentage of the litter entering the marine environment is assumed to come from land-based sources, but freshwater litter inputs have not been quantified. The lack of data and knowledge on fluxes of riverine litter to the sea, i.e., quantities and sources, hinders implementation of appropriate environmental regulations and mitigation measures. Estimations of riverine litter inputs require a consistent and harmonized approach to gather comparable data. The visual observation of floating litter on rivers has been selected as a simple and robust methodology for litter monitoring. A collaborative network of 36 institutions has been set-up for large spatial coverage. Currently 58 rivers are being observed regularly. A tablet computer application has been developed for the monitoring of floating macro litter (>2.5 cm) to harmonize the visual observations. The application allows recording of the observed items, their size and geo-position data during monitoring sessions. A common agreed list of litter items and size ranges is used, providing a common harmonized approach for data collection and reporting.
Litter, Plastics, Floating debris, Environmental monitoring, Pollution, Marine litter, Riverine input
González-Fernández, D., and Hanke, G., 2017. Toward a Harmonized Approach for Monitoring of Riverine Floating Macro Litter Inputs to the Marine Environment. Frontiers in Marine Science 4(86): 1-7. doi.org/10.3389/fmars.2017.00086.
While the use of plastic materials has generated huge societal benefits, the ‘plastic age’ comes with downsides: One issue of emerging concern is the accumulation of plastics in the aquatic environment. Here, so-called microplastics (MP), fragments smaller than 5 mm, are of special concern because they can be ingested throughout the food web more readily than larger particles. Focusing on freshwater MP, we briefly review the state of the science to identify gaps of knowledge and deduce research needs.
State of the science
Environmental scientists started investigating marine (micro)plastics in the early 2000s. Today, a wealth of studies demonstrates that MP have ubiquitously permeated the marine ecosystem, including the polar regions and the deep sea. MP ingestion has been documented for an increasing number of marine species. However, to date, only few studies investigate their biological effects.
The majority of marine plastics are considered to originate from land-based sources, including surface waters. Although they may be important transport pathways of MP, data from freshwater ecosystems is scarce. So far, only few studies provide evidence for the presence of MP in rivers and lakes. Data on MP uptake by freshwater invertebrates and fish is very limited.
While the research on marine MP is more advanced, there are immense gaps of knowledge regarding freshwater MP. Data on their abundance is fragmentary for large and absent for small surface waters. Likewise, relevant sources and the environmental fate remain to be investigated. Data on the biological effects of MP in freshwater species is completely lacking. The accumulation of other freshwater contaminants on MP is of special interest because ingestion might increase the chemical exposure. Again, data is unavailable on this important issue.
MP represent freshwater contaminants of emerging concern. However, to assess the environmental risk associated with MP, comprehensive data on their abundance, fate, sources, and biological effects in freshwater ecosystems are needed. Establishing such data critically depends on a collaborative effort by environmental scientists from diverse disciplines (chemistry, hydrology, ecotoxicology, etc.) and, unsurprisingly, on the allocation of sufficient public funding.
Chemistry, Ecotoxicology, Environmental quality, Litter, Microplastics, Monitoring, Plastics, Polymers, Review, Water framework directive
Martin Wagner, Christian Scherer, Diana Alvarez-Muñoz, Nicole Brennholt, Xavier Bourrain, Sebastian Buchinger, Elke Fries, Cécile Grosbois, Jörg Klasmeier, Teresa Marti, Sara Rodriguez-Mozaz, Ralph Urbatzka, A. Dick Vethaak, Margrethe Winther-Nielsen & Georg Reifferscheid (2014): Microplastics in freshwater ecosystems: what we know and what we need to know. Environmental Sciences Europe 26:12.