Influence of fish on habitat choice of water birds: a whole system experiment

It is notoriously difficult to study population interactions among highly mobile animals that cannot be meaningfully confined to experimental plots of limited size. For example, migratory water birds are believed to suffer from competition with resident fish populations for shared food resources. While observational evidence in support of this hypothesis is accumulating, replicated experiments addressing this issue at the proper spatial scale are lacking. Here, we report from a replicated whole-system experiment in which we stocked large (0.07 km2), shallow (< or =2.5 m deep), highly eutrophic ponds in the bird protection area "Ismaninger Speichersee mit Fischteichen" with different densities of carp and assessed the responses of water birds and their food resources during summer over several years. In all years, the biomasses of benthic macroinvertebrates, macroalgae, and macrophytes as well as the densities of herbivorous, carnivorous, and omnivorous water birds were reduced in carp ponds compared to fishless ponds. The negative effects of carp on food resources and on the numbers of water birds feeding in carp ponds increased over the season (May-September) and were stronger at high than at low stocking densities of carp. Consequently, differences in resource densities between ponds with and without carp increased, and the ranking of ponds with respect to resource densities became more predictable over the season. These factors may have contributed to a seasonal improvement of the birds' abilities to track resource densities across ponds, as suggested by tight correlations of bird numbers on ponds with resource densities late, but not early, in the season.     

Influence of permeability on nanoscale zero-valent iron particle transport in saturated homogeneous and heterogeneous porous media

Environmental Science and Pollution Research - Nanoscale zero-valent iron (NZVI) particles can be used for in situ groundwater remediation. The spatial particle distribution plays a very important...     

A review on human exposure to brominated flame retardants--particularly polybrominated diphenyl ethers

Brominated flame retardants (BFRs) have been and are still heavily used as additive or reactive chemicals in polymers and textiles. Only a few of the BFRs have been assessed in human subjects with a major data set on internal exposures to polybrominated diphenyl ethers (PBDEs). Increasing PBDE levels have been observed in mothers' milk from Sweden as well as in blood from Germany and Norway. The levels are in general lower than PCB levels. However, the PBDE concentrations found in the North Americans are considerably higher compared to European subjects. The PBDEs are dominated by 2,2',4,4'-tetrabromodiphenyl ether (BDE-47). Decabromodiphenyl ether (BDE-209) is reported both in the general population and in occupationally exposed persons showing the bioavailability of this high molecular weight compound. While the lower and medium brominated diphenyl ethers are persistent, BDE-209 has a fairly short half-life of approximately 2 weeks. Tetrabromobisphenol A (TBBPA) is readily eliminated in humans showing a half-life of about 2 days. Still, TBBPA is accumulated in humans but a continuous exposure to this BFR is required to maintain a certain level in the human subject. TBBPA has not been detected in the general population but in people exposed at work. The current review addresses human exposure routes and levels of BFRs.     

Lysosomen-ähnliche Kompartimente in Pflanzenzellen

The Science of Nature -     

Screening of heavy metal containing waste types for use as raw material in Arctic clay-based bricks

In the vulnerable Arctic environment, the impact of especially hazardous wastes can have severe consequences and the reduction and safe handling of these waste types are therefore an important issue. In this study, two groups of heavy metal containing particulate waste materials, municipal solid waste incineration (MSWI) fly and bottom ashes and mine tailings (i.e., residues from the mineral resource industry) from Greenland were screened in order to determine their suitability as secondary resources in clay-based brick production. Small clay discs, containing 20 or 40% of the different particulate waste materials, were fired and material properties and heavy metal leaching tests were conducted before and after firing. Remediation techniques (washing in distilled water and electrodialytical treatment) applied to the fly ash reduced leaching before firing. The mine tailings and bottom ash brick discs obtained satisfactory densities (1669–2007 kg/m³) and open porosities (27.9–39.9%). In contrast, the fly ash brick discs had low densities (1313–1578 kg/m³) and high open porosities (42.1–51. %). However, leaching tests on crushed brick discs revealed that heavy metals generally became more available after firing for all the investigated materials and that further optimisation is therefore necessary prior to incorporation in bricks.     

Vegetation phenology gradients along the west and east coasts of Greenland from 2001 to 2015

The objective of this paper is to characterize the spatiotemporal variations of vegetation phenology along latitudinal and altitudinal gradients in Greenland, and to examine local and regional climatic drivers. Time-series from the Moderate Resolution Imaging Spectroradiometer (MODIS) were analyzed to obtain various phenological metrics for the period 2001–2015. MODIS-derived land surface temperatures were corrected for the sampling biases caused by cloud cover. Results indicate significant differences between West and East Greenland, in terms of both observed phenology during the study period, as well as the climatic response. The date of the start of season (SOS) was significantly earlier (24 days), length of season longer (25 days), and time-integrated NDVI higher in West Greenland. The sea ice concentration during May was found to have a significant effect on the date of the SOS only in West Greenland, with the strongest linkage detected in mid-western parts of Greenland.