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.

Ammonia and chromate interaction explains unresolved Hyalella azteca mortality in Flanders' sediment bioassays.

Agricultural, industrial and household chemicals are emitted in large rivers along populated areas, transported by water and deposited in sediments, posing (eco)toxicological risks. Sediments have received less attention than surface waters, likely because of the intrinsic complexity of interactions between sediment constituents complicating correct framing of exposures. Sadly, thorough assessment of the in situ behavior of sediment constituents in bioassays is often not practical.

Bioconcentration of Organotin Cations during Molting Inhibits Growth.

The densely populated North Sea region encompasses catchments of rivers such as Scheldt and Meuse. Herein, agricultural, industrial, and household chemicals are emitted, transported by water, and deposited in sediments, posing ecological risks. Though sediment monitoring is often costly and time-intensive, modeling its toxicity to biota has received little attention.

The inland water macro-invertebrate occurrences in Flanders, Belgium.

The Flanders Environment Agency (VMM) has been performing biological water quality assessments on inland waters in Flanders (Belgium) since 1989 and sediment quality assessments since 2000. The water quality monitoring network is a combined physico-chemical and biological network, the biological component focusing on macro-invertebrates. The sediment monitoring programme produces biological data to assess the sediment quality.

Internal Loading and Redox Cycling of Sediment Iron Explain Reactive Phosphorus Concentrations in Lowland Rivers.

The phosphate quality standards in the lowland rivers of Flanders (northern Belgium) are exceeded in over 80% of the sampling sites. The factors affecting the molybdate reactive P (MRP) in these waters were analyzed using the data of the past decade (>200 000 observations). The average MRP concentration in summer exceeds that winter by factor 3.

Use of a macroinvertebrate based biotic index to estimate critical metal concentrations for good ecological water quality.

Large datasets from total and dissolved metal concentrations in Flemish (Belgium) fresh water systems and the associated macroinvertebrate-based biotic index MMIF (Multimetric Macroinvertebrate Index Flanders) were used to estimate critical metal concentrations for good ecological water quality, as imposed by the European Water Framework Directive (2000). The contribution of different stressors (metals and water characteristics) to the MMIF were studied by constructing generalized linear mixed effect models. Comparison between estimated critical concentrations and the European and Flemish EQS, shows that the EQS for As, Cd, Cu and Zn seem to be sufficient to reach a good ecological quality status as expressed by the invertebrate-based biotic index.

Sources of PCDD/Fs, non-ortho PCBs and PAHs in sediments of high and low impacted transboundary rivers (Belgium-France).

PAHs, PCDD/Fs and non-ortho PCBs have been assessed in Yser and Upper-Scheldt river sediments. Higher contamination levels were observed in the Upper-Scheldt sediments: maximum concentrations for the 16 US-EPA PAHs, PCDD/Fs and non-ortho PCBs respectively amount to 8.9 mg kg(-1), 12 ng TEQ kg(-1) and 5.

A new risk assessment approach for the prioritization of 500 classical and emerging organic microcontaminants as potential river basin specific pollutants under the European Water Framework Directive.

Given the huge number of chemicals released into the environment and existing time and budget constraints, there is a need to prioritize chemicals for risk assessment and monitoring in the context of the European Union Water Framework Directive (EU WFD). This study is the first to assess the risk of 500 organic substances based on observations in the four European river basins of the Elbe, Scheldt, Danube and Llobregat. A decision tree is introduced that first classifies chemicals into six categories depending on the information available, which allows water managers to focus on the next steps (e.

Caged midge larvae (Chironomus riparius) for the assessment of metal bioaccumulation from sediments in situ.

First-stage larvae of the midge Chironomus riparius were exposed in small enclosures at 19 sites located in three different river basins in Flanders (Belgium). Sediments were sampled and sieved at 200 microm at all exposure sites. A layer of approximately 2 cm of sediment was placed in each cage and 100 midge larvae were added.