A Comprehensive Monitoring and Assessment Survey on the Danube - page 03

Heavy Metals and Arsenic

In general, the concentrations of heavy metals and arsenic in water, and the contents of metals and metalloids in suspended particulate matter and bottom sediments estimated during JDS3 were similar to those observed in the JDS1 and JDS2 samples. Comparison of results in water with WFD environmental quality standards showed occasional and scattered non-conformity primarily for Ni and Pb. For mercury and arsenic there were no violations of limits at all. For heavy metals and arsenic in suspended particulate matter (SPM) the quality standards applied in the past for JDS were used also during JDS3 and they were not exceeded for Cd, Cr, Hg and Pb. The target value for As in SPM was not met at one site, for Cu at three sites, for Ni at 20 sites and for Zn at seven sites. In sediment the German targets for metals were with one exception met at all sites for all elements. Only copper at JDS48 exceeded the quality target value of 160mg/kg by a factor of 3.3.

At six sites Hg was also determined in dried fish tissue. Results ranged between 0,11 to 0,35mg/kg wet weight. In addition three fish samples taken during JDS2 in 2007 and properly stored in between were also analyzed. Results were comparable with those of 2013 giving Hg contents of 0,21 – 0,44mg/kg wet weight. All these results were clearly above the EQS set by 2008/105/EC and 2013/39/EU exceeding it by factors between 5 and 18.

Organic Substances

Diethylhexylphthalate (DEHP) has been used as a plasticizer worldwide in huge amounts for many years. During the JDS2, it was the most problematic priority pollutant, exceeding the EQS in 44% of water samples. However, during the JDS3, while DEHP in water was present in all samples, it was significantly below the EQS. DEHP was also found in higher concentrations in SPM and sediments during the JDS3, which shows that this pollutant is accumulating. Maximum concentrations in SPM and sediment samples were at JDS38 (upstream Pančevo/downstream Sava) and JDS9 (Klosterneuburg), respectively. Still, all concentrations were far below quality standards for the protection of bottom-dwelling organisms.

Perfluorooctansulfonic acid (PFOS) is a new priority substance under the WFD that repels water and oil and is resistant to heat and chemical stress. For the JDS3, PFOS exceeded the EQS at 94% of sampling sites.

As many pesticides and biocides are applied in April/July, the JDS3 sampling in August/September was not reflecting the application peak – therefore, only low concentrations were detected. Diuron, isoproturon and terbutryn (a "new" priority substance) were found to be below EQS.

C10-C13-chloroalkanes are widely used as plasticizers, additives in lubricants, cutting fluids and flame retardants. For the first time, C10-C13-chloroalkanes were analyzed in the whole of the Danube River. All concentrations were found to be below the EQS.

Organotin compounds are used as biocides and in PVC manufacturing. Concerns over their toxicity have led to a range of restrictions in use, including EQS for tributyltin. During the JDS3, tributyltin was found at seven of 68 sites with values above the EQS: all sites with positive results were in the Upper/Middle Danube with the highest concentrations at JDS7 (upstream AbwindenAsten) and JDS12 (tributary Morava). Dibutyltin is also regulated in some countries, but no exceedances were observed during the JDS3. A comparison with the results of the JDS2 showed lower maximum values for tributyltin (and also dibutyltin) in 2013 – this reflects the effects of restrictions on this substance.

Hexabromocyclododecane (HBCDD) is a new priority substance. It is used as a flame retardant, mainly by the polymer and textile industry (e.g. in polystyrene insulation panels in building construction). For HBCDD, all samples showed values below the new EQS in biota.

AMPA, a degradation product of glyphosate (currently the most used herbicide worldwide but not regulated as a priority substance), was detected in most water samples with an unusually stable concentration level in all sections of the Danube. Concentrations up to five times higher in some tributaries had little influence on concentrations in the Danube.

Diclofenac, an important anti-inflammatory drug, is on the EU 'Watch-List' for priority pollutants (a proposal designed to allow targeted EU-wide monitoring of substances of possible concern) with a proposed EQS. The only JDS3 sample to exceed this proposed EQS was from the Arges River.

Dioxins and dioxin-like compounds are new priority substances. Analyses were performed on polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), indicator polychlorinated biphenyl congeners (EC-6 PCBs) and dioxin-like PCBs (DL-PCBs) in selected samples of SPM and fish (Abramis brama). For PCDD/Fs and PCBs, none of the existing EQS values for aquatic biota and suspended solids/sediments, and none of the EU food limits concerned, were exceeded in the Danube.

Organophosphorus compounds (OPCs) are commonly used as flame retardants in a variety of products, such as electronic equipment, plastics, rubbers, textiles and building materials.


Since many brominated flame retardant (BFRs), including PBDEs, were banned in recent years, the use of OPCs as a substitute for PBDEs has increased. As a result, OPCs have been detected in many environments, such as effluent from sewage treatment plants. Generally, there are no local OPC emissions of concern for the Danube catchment. Among OPCs, TCPP clearly dominates in both the Danube and its tributaries. The concentrations for all OPCs were found several orders of magnitude below their toxic effect levels for aquatic wildlife.

New Techniques

During JDS3 several new analytical techniques and strategies were applied. The effect-based screening focused on the presence of non-regulated organic substances in the Danube using a newly developed mobile large-volume extraction device (LVSPE) to concentrate water samples of up to 1000 litres on-site during the JDS3. The extracts were then analyzed for 264 water phase relevant organic compounds using liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS) in support of the effect-based screening with a set of different in vitro and in vivo bioassays. Despite the overall low concentrations of organic compounds, all extracts were effective in one or more bioassays with the endpoints mutagenicity, dioxin-like and PXR mediated activity, oxidative stress responses and estrogenicity as well as growth inhibition and photosystem II inhibition of green algae. Extract from site JDS33 (downstream Novi Sad) and JDS63 (tributary Siret) were among the samples showing the most toxic potential, which were effective in almost all bioassays.

The non-target screening was performed at a basin-wide scale based on UHPLC-QTOF-MS and LC-HR-MS techniques with the major goal to search for as many compounds as possible. Initial results from non-target screening by UHPLC-QTOF-MS revealed presence of more than 3370 different organic compounds listed by name (PCDL match). The follow up evaluations using the AutoMSMS method resulted in unequivocal identification of 56 substances dominated by pesticides, pharmaceuticals and personal care products. The rest of the tentatively identified suspect compounds, unknowns (proposed molecular formula) and total unknowns (only accurate mass and retention time available) still need to be investigated and those results can be expected in the future. The 'suspect screening' by LC-HR-MS showed that 110 out of 315 'searched for' substances were determined in at least one sample and 50 compounds were present in more than 20 samples (Figure 5). A semi-quantitative analysis was performed for 110 analytes. Despite the lists of target/suspect substances in two laboratories carrying out this exercise differ, there is a good agreement on the overlapping compounds, e.g. DEET found by both laboratories in all 68 samples and gabapentin in 67 vs. 65 samples with LC-QTOF-MS and LC-HR-MS, respectively.

An alternative sampling approach to detect the trace concentrations of organic substances was tested during JDS3. The passive samplers were exposed to the Danube water for a period of up to two days to adsorb the dissolved pollutants. Despite the low or sub-ng.l-1 concentrations of most organic pollutants present in the free dissolved phase, passive sampling enabled to clearly identify spatial gradients of a broad range of organic pollutants in the water column, including PCBs, organochlorine compounds, PAHs, alkylphenols, selected polar pesticides and pharmaceuticals. In many cases, the integrative character of passive sampling allowed measurement of compounds down to pg.l-1 levels where methods based on low volume spot sampling of water applied in the previous JDS2 survey failed to detect them.

A specific biomarkers based assay was used detecting the genotoxic pollution by comet assay in haemolymph of mussels and in peripheral erythrocytes of fish species. The highest levels of DNA damages were observed in specimens collected in section between Baja and Velika Morava (comet assay) and in sections between Bazias and Orsova and between Guirgeni and Reni (micronucleus assay). The metropolitan region of Bucharest/Ruse showed significant highest values of micronucleus formation in erythrocytes of A.alburnus. Lower values in the comet assay at these sites may indicate different genotoxic modes of action.

Links to Groundwater

For the first time the link between contamination of surface water and groundwater was explored. A number of emerging substances were detected during JDS3 in the abstraction wells at bank filtration sites. This phenomenon can be expected for substances like amidotrizoic acid, iopamidol, acesulfame, benzotriazole or carbamazepine which are known to be quite persistent in the aquatic environment and which are mostly not completely retained by bank filtration. However, due to the relatively low concentration levels in the Danube, concentrations in the abstraction wells were mostly below 0.1 µg/L for most substances. An exception was the artificial sweetener acesulfame which occurred in concentrations up to 1.1 µg/L in the Danube and was detected in most of the abstraction wells with a maximum concentration of 0.45 µg/L. Acesulfame is used as a food additive and the observed concentrations are not considered to be harmful for humans. However, acesulfame can act as an example for a more or less persistent and very mobile substance which is consumed in large quantities.

Figure 5: Frequency of appearance of 110 ‘identified’ suspect pollutants (315 tested) in JDS3 surface water samples; results obtained from non-target screening workflow by HPLC-ESI-Q-TOF-MS operated in ESI+ and ESI – modes.