Incidental P losses from non-point sources may contribute to eutrophication and to decreased soil fertility. These incidents have been related to heavy rainfall on freshly fertilized agricultural soils and little is known about such incidents on more natural soils or in forests. The aim of this work is to determine if incidents of high P leaching also occur in spruce forests, and if such incidents are of significance in P cycling. We found a peak in the mineral soil solution showing that single events of high P leaching occur. The orthophosphate concentration in the Bf-horizon of the 80-year old spruce forest peaked in the autumn of the second year of a continuous monitoring. The concentration increased by more than 85 times compared to the highest concentration obtained earlier during the sampling. The amount leached during this 6 months peak is 10 times higher than the average annual leaching. This P leaching might be due to a combination of high P deposition/through-fall and a high anion exchange with dissolved-organic-carbon and Cl-. We suggest that single events of high sub-surface P leaching may contribute to the overall P leaching, and might increase with the global warming as more DOC is expected to be released to the soil solution.

The vast quantities of bauxite residue generated globally necessitate environmentally responsible disposal strategies. This study investigated the long-term (5-year) behavior of modified bauxite residue (MBR) with an initial pH of 8.5, using lysimeters to test various configurations: raw MBR, sand/soil capping, revegetation, and used MBR (UMBR) previously applied for acid mine drainage remediation. Throughout the 5-year experiment and across all configurations, the pH of the leachates stabilized between 7 and 8 and their salinity decreased. Their low sodium absorption ratio (SAR) indicated minimal material clogging risk and suitability for salt-tolerant plant growth. Emission of potentially toxic elements (except V) decreased rapidly after the first year to low levels. Leachate concentrations consistently remained below LD50 for Hyelella Azteca, at least an order of magnitude lower by the experiment's end (except for first-year Cr). Sand capping performed poorly, while revegetation and soil capping slightly increased emissions, though these were negligible given the low final emission levels. Revegetated MBR shows promise as a suitable and sustainable solution for managing bauxite residues, provided the pH is maintained above 6.5. This study highlights the importance of long-term assessments and appropriate management strategies for bauxite residue disposal.