Mixtures of sediment chemical contaminants at freshwater sampling sites across Europe with different contaminant burdens.

Extended chemical analyses of fluvial sediments were undertaken to establish the key pollutant pressures and mixtures present across nine European Union inland waterways. A wide range of chemical components and physical parameters were investigated including substances from the EU Priority List and Watch List. The data set was examined for key indicator compounds, however it was found that a wide range of pollution pressures were present in the different sediments including organic hydrocarbons, metal(loid)s, nutrients, polycyclic aromatic hydrocarbon (PAH), polychlorinated biphenyl (PCB) compounds, perfluoroalkyl and polyfluoroalkyl substances and pesticides, some of which exceeded regulatory guidance at different sampling points. The presence of such a wide range of compounds underpins the complex chemical composition of sediments that have acted as sinks for many decades absorbing contaminants from urban, industrial and agricultural sources. This dataset has been used to describe average overall toxicity of the sediments sampled, a calculation which was based on key components identified by Principal Component Analysis (PCA) and for those that had existing freshwater sediment regulatory values. A total of 33 components were used including PCBs, PAHs, metal(iod)s and pesticides. This analysis reflected the contamination of each site, with most indicating some level of toxicity during the sampling period. Watch List chemicals triclosan (TCS) and diclofenac (DIC) were also investigated; levels were relatively low, typically 10-100's ng L-1, however they were present at all sampling sites. The dataset is available as a resource for future chemical, and toxicological, sediment analysis comparisons.

Brownfield sites promote biodiversity at a landscape scale.

Repurposing of brownfield sites is often promoted, because it is perceived that protecting the "green belt" limits damage to biodiversity; yet brownfield sites provide scarce habitats with limited disturbance, so conversely are also perceived to be ecologically valuable. Combining data from three national-scale UK biological monitoring schemes with location data on historical landfill sites, we show that species richness is positively associated with both the presence and increasing area of ex-landfill sites for birds, plants and several insect taxa. Assemblage rarity of birds is also positively associated with presence of ex-landfill sites. Species richness associated with ex-landfill sites declined over time for birds and insects but increased over time for plants. These findings suggest that development of brownfield sites may have unintended negative consequences for biodiversity, and imply that to minimise loss of biodiversity, brownfield site repurposing could be targeted towards smaller sites, or sites in areas with a high density of other brownfield sites.