Much of the phosphorus (P) applied as fertilizer on agricultural fields enters inland waters, estuaries, and the sea. This session deals with the transport of P along freshwater and marine systems, including leaching from arable land or other sources and the impact on the respective ecosystem. Phosphorus enters aquatic systems as a nutrient for plants and as a component of herbicides and insecticides. In all ecosystems (terrestrial, freshwater, and marine), it undergoes constant transformation and thereby intervenes in nearly all biogeochemical processes. The scale of influence of P ranges from the cellular, as a regulator of growth and cell function, to the ecosystem, in the form of element cycling. Accordingly, P studies ranges from microscopic measurements to ecosystem modeling. The aim of environmental P investigations is to better understand P fluxes and cycles and to establish effective protection and rehabilitation measures.

Key concepts:

• P loads in marine and freshwater systems (e.g., leaching of P from arable land)
• P in aquatic environments: sources, impact, transport, and fate
• Phosphatase (activity) in soil and water
• P in the regulation of growth and cell functions
• P in biogeochemical processes (freshwater, marine, and terrestrial ecosystems)
• Natural and anthropogenic organic P compounds in the environment
• Exchange processes between solid and liquid phases
• Modeling

Responsible scientists: Prof. Dr. Ulrich Bathmann, Dr. Monika Nausch (both from the Leibniz Institute for Baltic Sea Research)

Animal and plant systems, both terrestrial and aquatic, account for a large proportion of the P cycle. P leaving this cyclic P flux is mostly in the form of undesired losses from agricultural systems into natural terrestrial and aquatic environments, leading to eutrophication and other ecological challenges. While previous fertilization practices were directed at building-up P reserves in soil, current concerns are related to environmental P pollution and the rising price of P on the world market. Together, they strongly call for new recommendations regarding the agricultural use of P and the more sustainable use of this scarce resource. Accordingly, this conference session addresses the availability of P compounds in soils, the efficiency of intrinsic P utilization by plants and animals, the optimization of recycling processes of excreted P, and the minimization of P losses from agricultural production systems.

Keywords: plant, animal, soil, aquaculture, feeding, manuring, fertilization, rhizosphere

Responsible scientists: Prof. Dr. Peter Leinweber, Prof. Dr. Bettina Eichler-Löbermann (both from the University of Rostock), Prof. Dr. Klaus Wimmers (Leibniz Institute for Farm Animal Biology)

Phosphorous is a strategic resource for which there is neither substitute nor replacement. This calls for fostering both the recovery of P and its return into the nutrient cycle, i.e., recycling. In recent years, many initiatives, extensive research, and several demonstration projects on P-recycling have been launched and realized at different scales. Technologies aimed at P recovery and recycling have been developed to tap this precious element from different sources, yielding various recyclates or even final products, but full-scale applications are limited. These efforts have been accompanied by continued research and political discussions on the implementation of effective P recycling strategies. In its focus on phosphorous recycling, this session will host a series of implementation-oriented discussions: Which technological approaches are promising from legal, logistic, and marketing perspectives? What can be learned from the experience with full-scale recovery, recycling, and product valorization? Which key hurdles must be overcome or bypassed to implement P recovery and recycling in and across different economic sectors?

Keywords: recycling technologies, recovery, valorization, hurdles, full-scale application

Responsible scientist: Prof. Dr. Jens Tränckner (University of Rostock)

This session considers P compounds in all oxidation states, ranging from low-valent compounds in low oxidation states to those regularly used for catalytic purposes and beyond. The structural versatility of P has led to the isolation of a large number of unusual novel P species, and thus to detailed studies of their often fascinating properties. In lectures and poster sessions, the many facets of the synthetic chemistry of phosphorus, the vast applications for catalytic purposes, as well as analytic and theoretical studies of P compounds in all their versatility will be presented.

Keywords: phosphorus compounds, synthesis, catalytic application, oxidation states, properties

Responsible scientists: Prof. Dr. Marko Hapke, Dr. Thomas Werner (both from the Leibniz Institute for Catalysis)

This session will address the many novel and advanced analytical approaches that enable the identification, speciation, and quantification of P-containing compounds in environmental and technical systems. The respective methods include quantum-chemical and other modeling approaches, synchrotron-based techniques, nuclear magnetic resonance spectroscopy, and mass spectrometry, the latter often combined with gas- or liquid-chromatographic separations or other chemical-analytical methods. Among the analytical targets are P compounds in complicated environmentally relevant mixtures such as sediment, soil, by-products, and waste. An additional focus will be the many natural and anthropogenic P compounds in biological systems and their medical applications.

Responsible scientists: Prof. Dr. Peter Leinweber (University of Rostock), Prof. Dr. Detlef Schulz-Bull (Leibniz Institute for Baltic Sea Research Warnemünde)

This session examines the policy measures and societal changes that promote or prevent a sounder, more informed use of phosphorus. So far, P supplies have been addressed in tentative proclamations rather than in legally binding measures. However, traditional regulatory measures focusing on single actions, i.e., the command-and-control approach, are unlikely to suffice as solutions to resource and environmental problems. Instead, P problems are more appropriately viewed as quantity-related. Additional economic instruments will be needed to avoid enforcement deficits, prohibit rebound and shifting effects, and promote recycling while decreasing P consumption. Whether policy measures, including economic instruments, will contribute simultaneously to solving environmental problems regarding land use, resources, biodiversity loss, and climate change remains to be seen.

Responsible scientist: Prof. Dr. Felix Ekardt (University of Rostock and Research Unit Sustainability and Climate Policy)

Additional Session on Wednesday.