Semivolatiles in the Forest Environment - The Case of PAHs

Forests are an important sink for semivolatile organic compounds (SVOCs) due to the great aerodynamic roughness of woodland landscape which enhances downward fluxes of both gaseous and particle-bound pollutants and the slow turnover of soil organic content. In particular, Polycyclic Aromatic Hydrocarbons (PAHs) are the most abundant persistent organic toxics in forests. Due to their lipophilic properties PAHs accumulate in soil, sediment and living organisms. PAHs emitted to the atmosphere by combustion processes are transported by air masses and are subject to dry or wet deposition. In forests PAHs are mainly present in the soil compartment, therefore the forest biomass can be regarded as a pump of pollutants from the atmosphere to the soil from which chemicals can return to the atmosphere only with difficulty. In the atmosphere, the main processes responsible for PAH degradation are photolysis and oxidation by gaseous pollutants, while microbial metabolism is the major process for the degradation of PAHs in soil.JRC.DDG.F.9-Sustainable Transport (Ispra

Threshold or Limit? Precipitation Dependency of Austrian Landslides, an Ongoing Challenge for Hazard Mapping under Climate Change

Climate change is set to increase landslide frequency around the globe, thus increasing the potential exposure of people and material assets to these disturbances. Landslide hazard is commonly modelled from terrain and precipitation parameters, assuming that shorter, more intense rain events require less precipitation volume to trigger a slide. Given the extent of non-catastrophic slides, an operable vulnerability mapping requires high spatial resolution. We combined heterogeneous regional slide inventories with long-term meteorological records and small-scale spatial information for hazard modelling. Slope, its (protective) interaction with forest cover, and altitude were the most influential terrain parameters. A widely used exponential threshold to estimate critical precipitation was found to incorrectly predict meteorological hazard to a substantial degree and, qualitatively, delineate the upper boundary of natural conditions rather than a critical threshold. Scaling rainfall parameters from absolute values into local probabilities (per km²) however revealed a consistent pattern across datasets, with the transition from normal to critical rain volumes and durations being gradual rather than abrupt thresholds. Scaled values could be reverted into site-specific nomograms for easy appraisal of critical rain conditions by local stakeholders. An overlay of terrain-related hazard with infrastructure yielded local vulnerability maps, which were verified with actual slide occurrence. Multiple potential for observation bias in ground-based slide reporting underlined the value of complementary earth observation data for slide mapping and early warning

A Comparison of Alpine Emissions to Forest Soil and Spruce Needle Loads for Persistent Organic Pollutants (POPs)

The project MONARPOP analysed the concentrations of semivolatile organic compounds (SVOCs) in two important sink compartments, needles of Norway spruce (Picea abies [L.] Karst.) and forest soil from 40 remote Alpine forest sites in Austria, Germany, Italy, Slovenia and Switzerland. In the present study the load of PCDD/F, PCB, PBDE, PAH, HCB, HCH and DDT in the Alps calculated on the basis of measured data are compared with their estimated emissions in the Alpine region. It comes out that the masses of the studied pollutants stored in the forests are higher than the corresponding emissions in the Alpine area indicating that the Alps are a sink for POPs advected from surrounding areas. It is assumed that local emissions of PCDD/F and PAH deriving from biomass burning are probably underestimated and that the pool of these pollutants in the forests represents the accumulation over some decades.JRC.H.4-Transport and air qualit