Nature-based solutions for nutrient pollution control in European agricultural regions: A literature review

There is an increasing attention on Nature-based Solutions (NBS) to address social and environmental challenges in Europe, including the control of excess nutrients conveyed by agricultural regions. Indeed, the excess of nutrients has been recognized as one of the main reasons of failure to achieve a good ecological status of water bodies, according to the European Water Framework Directive 2000/60/EC. In this study we consider NBS to control two main sources of nutrient pollution in agricultural regions: excess manure from intensive livestock breeding, and diffuse pollution due to fertilizers applied on fields. The NBS typically adopted to address these two sources of pollution are wetlands in addition, for diffuse pollution, to vegetated drainage ditches and buffer strips. From a review of 767 peer review articles, we built a dedicated dataset including a total number of 444 NBS cases. These were analysed to obtain an overview of: (i) the range of climate, landscape and design variables under which the above typologies of NBS have been implemented; (ii) their performances for nutrient pollution control, in terms of removal efficiency on concentrations and mass load removal per unit of surface; (iii) the relationships between landscape, climate, and design variables and treatment performance. The results are presented in order to guide future planning of NBS for pollution control in European agricultural regions.