Synthetic superabsorbents (sSAPs) have been used as technical soil additives for decades. They enhance the water-holding capacity of soil, helping agricultural and forestry systems to adapt to increasingly frequent dry spells. In recent years, their importance in the context of climate change has grown considerably. However, our understanding of how they are actually used and behave in the environment remains inadequate. Notably, reliable data on the intensity of use, types of products employed, and spatial distribution in the Upper Rhine region is lacking. Furthermore, there are clear discrepancies between the regulatory approval criteria and the experimentally determined degradation behaviour, and the actual disposition of sSAPs in the environment.
Although regulatory approval procedures are often based on standardised laboratory conditions, recent studies suggest that the transformation and degradation of substances in soil is significantly more complex than previously thought and has not yet been adequately characterised. Of particular relevance in this context is the fact that sSAPs are increasingly being discussed in connection with the formation of persistent, microplastic-like residues. These residues can accumulate in soil over time, altering soil pore systems and impairing key soil functions. This fundamentally shifts the perception of sSAPs from a purely functional soil improvement measure to a potential source of long-term environmental impact.
In the Upper Rhine region, uncertainty surrounding data and assessments is exacerbated by sensitive contextual factors. The region is characterised by increasing drought stress, intense rainfall and extensive agricultural activity. This increases the use of sSAPs and their associated risks. At the same time, there are significant differences in assessment, regulatory and application practices between Germany, France and Switzerland.
Against this backdrop, the SOPLAS project was launched. For the first time, it aims to systematically and comparably record and assess the specific needs, actual use, environmental behaviour and long-term effects of sSAPs across borders. It will identify ambiguities and establish a solid foundation for future practical and policy decisions.
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