Sources of nitrogen heterocyclic PAHs (N-HETs) along a riverine course.

For the first time the occurrence of 26 nitrogen heterocyclic polyaromatic hydrocarbons (N-HETs) and the antiepileptic drug carbamazepine (CBZ) as a marker for anthropogenic influence was determined in an entire river system and its influents. Besides the investigation of diurnal and annual variations in concentrations, dilution and load calculations, the aims were to facilitate transferability to other rivers by identifying sources of the different substances. To create a sufficient database over 180 aqueous samples from the River Fuhse (Lower Saxony, Germany), its catchment area, effluents of municipal and industrial wastewater treatment plants (WWTPs) and rainwater were analyzed. Typical substances found in background water samples and rain samples were quinoline and isoquinoline, whereas 1-/3-methylisoquinoline were traced back to an industrial WWTP. Due to similar concentration levels in the effluents of municipal WWTPs, their impact on the river correlated with their nominal loads. In municipal WWTP effluents CBZ (cmedian=1693ngL-1), 2-methylquinoline (cmedian=64ngL-1), and acridine (cmedian=62ngL-1) prevailed. Although the occurrence of N-HETs at contaminated sites is a widely discussed scientific topic, this study showed that the investigated site was a source with only small volumetric contribution to N-HET concentrations in the adjacent river. In total the River Fuhse discharges 20kga-1 N-HETs and 21kga-1 CBZ into the receiving river.

Bioaccumulation in aquatic systems: methodological approaches, monitoring and assessment.

Bioaccumulation, the accumulation of a chemical in an organism relative to its level in the ambient medium, is of major environmental concern. Thus, monitoring chemical concentrations in biota are widely and increasingly used for assessing the chemical status of aquatic ecosystems. In this paper, various scientific and regulatory aspects of bioaccumulation in aquatic systems and the relevant critical issues are discussed. Monitoring chemical concentrations in biota can be used for compliance checking with regulatory directives, for identification of chemical sources or event-related environmental risk assessment. Assessing bioaccumulation in the field is challenging since many factors have to be considered that can affect the accumulation of a chemical in an organism. Passive sampling can complement biota monitoring since samplers with standardised partition properties can be used over a wide temporal and geographical range. Bioaccumulation is also assessed for regulation of chemicals of environmental concern whereby mainly data from laboratory studies on fish bioaccumulation are used. Field data can, however, provide additional important information for regulators. Strategies for bioaccumulation assessment still need to be harmonised for different regulations and groups of chemicals. To create awareness for critical issues and to mutually benefit from technical expertise and scientific findings, communication between risk assessment and monitoring communities needs to be improved. Scientists can support the establishment of new monitoring programs for bioaccumulation, e.g. in the frame of the amended European Environmental Quality Standard Directive.

Inside-sediment partitioning of PAH, PCB and organochlorine compounds and inferences on sampling and normalization methods.

Comparability of sediment analyses for semivolatile organic substances is still low. Neither screening of the sediments nor organic-carbon based normalization is sufficient to obtain comparable results. We are showing the interdependency of grain-size effects with inside-sediment organic-matter distribution for PAH, PCB and organochlorine compounds. Surface sediment samples collected by Van-Veen grab were sieved and analyzed for 16 PAH, 6 PCB and 18 organochlorine pesticides (OCP) as well as organic-matter content. Since bulk concentrations are influenced by grain-size effects themselves, we used a novel normalization method based on the sum of concentrations in the separate grain-size fractions of the sediments. By calculating relative normalized concentrations, it was possible to clearly show underlying mechanisms throughout a heterogeneous set of samples. Furthermore, we were able to show that, for comparability, screening at < 125 µm is best suited and can be further improved by additional organic-carbon normalization.