Workshop: Towards solutions to reduce nutrient fluxes to inland waters and the ocean – Understanding the processes and time scales of nutrient retention, cycling and export

1 Dec 2025, 09:00 → 2 Dec 2025, 17:00 Europe/Berlin

254 (lecture hall) (UFZ Leipzig, Building 1.0)

Jan Fleckenstein (Helmholtz-Zentrum für Umweltforschung - UFZ Leipzig), Jette Wüst (UFZ (HDG/ZENCO)), Anna Gorski (ÖA)

This workshop is financed by the UFZ-internal funding call: From planetary boundaries to ‘planetary’ solutions.

Please register until 11^th August 2025 via the button at the end of the page.

Rationale:

Excessive inputs of nutrients (N, P) into our landscapes have led to a build-up of large nutrient stocks in soils, sediments and groundwater that cause severe and long-lasting impacts on inland waters and the downstream receiving oceans (eutrophication, algal blooms). According to the planetary boundaries framework by Richardson et al. (2023), we are operating outside the safe operating space for humanity in terms of global flows of nutrients from the land into freshwater systems and eventually into the ocean. Due to long transport time scales of some nutrients from diffuse sources (e.g. nitrogen), measures to reduce nutrient inputs (e.g. via regulation of agricultural nutrient inputs) may only yield improvements in receiving waters after years to decades, and therefore can only serve as a long-term strategy. For shorter-term mitigation strategies measures need to be considered that enhance the retention and attenuation capacity of landscapes (e.g. in wetlands and riparian zones) and in the inland waters themselves (via instream processing and retention). While it is well known that rivers and lakes have a natural self-purification capacity, under current conditions this capacity is exceeded by far. In other words, inland waters are unable to process the nutrient loads they receive, leading to high exports of nutrients (especially nitrogen and phosphorus) to the oceans. For sustainable solutions to this planetary problem, long-term strategies (e.g. input reductions) need to be combined with shorter-term measures (e.g. enhanced attenuation – nature based solutions). For a tractable implementation of measures at both levels, a thorough scientific understanding of the processes that control the mobilization, transport (including transport time scales), and retention of nutrients (in specific landscape compartments and inland waters) is required.

To address these challenges, this workshop aims to serve as a platform for bringing together national and international experts in hydrology/hydrogeology, biogeochemistry, ecology, and microbiology as well as partners and stakeholders in agriculture water management, to develop strategies and measures at different spatial scales. A comparison of implementation strategies in the different national contexts of the involved experts will also be part of the workshop to exchange information on different management and policy approaches used to curb nutrient inputs and diffuse pollution management.

Objectives:

Objectives of this workshop are to identify strategies that minimize long-term nutrient inputs and at the same time maximize nutrient retention and attenuation in the landscape and freshwater ecosystems, understand and quantify nutrient export timescale as a prerequisite for robust long-term strategies, enable new ideas for nutrient recovery from ecosystem and subsequent use in agriculture, and discuss ways of increasing in-stream nutrient cycling for planetary solutions to reduce nutrient export to inland waters and the ocean. In short, recommendations for practical actions at local and regional scales to enhance retention, cycling, and recovery of nutrients within landscapes and freshwater systems before they reach the ocean, thereby improving nutrient sustainability and preventing negative ecological impacts.

Expected outcomes:

●        Writing and publication of a perspective paper

●        Formulation of potential long- and short term measures with reference to different national contexts

●        Building a network of peers and experts in the field of nutrient dynamics and export and in-stream nutrient cycling, which encompasses transdisciplinary understanding and different spatial scales (local, regional and global)

●        Preparation of a joint research proposal

External invitees*:

●        Dr. Chris Green, USGS, USA

●        Dr. Gabriele Weigelhofer, WCL, Austria

●        Dr. H.E. Dahlke, University of California, Davis, USA

●        Dr. Anna Mencio Domingo, University of Girona, Spain

●        Dr. Brian Kronvang, Arhus University, Denmark

●        Dr. Anna Lupon, CEAB-CSIC, Spain

●        Dr. Joachim Rozemeijer, Deltares

●        Dr. Anker Lajer Højberg, GEUS, Denmark