European Water Framework Directive Research Articles

Environmental DNA clarifies impacts of combined sewer overflows on the bacteriology of an urban river and resulting risks to public health

There is no reference of microbiological water quality in the European Union's Water Framework Directive, adapted into English law, and consequently microbial water quality is not routinely monitored in English rivers, except for two recently designated bathing water sites. To address this knowledge gap, we developed an innovative monitoring approach for quantitative assessment of combined sewer overflow (CSO) impacts on the bacteriology of receiving rivers. Our approach combines conventional and environmental DNA (eDNA) based methods to generate multiple lines of evidence for assessing risks to public health. We demonstrated this approach by investigating spatiotemporal variation in the bacteriology of the Ouseburn in northeast England for different weather conditions in the summer and early autumn of the year 2021 across eight sampling locations that comprised rural, urban, and recreational land use settings. We characterized pollution source attributes by collecting sewage from treatment works and CSO discharge at the peak of a storm event. CSO discharge was characterized by log10 values per 100 mL (average ± stdev) of 5.12 ± 0.03 and 4.90 ± 0.03 for faecal coliforms and faecal streptococci, and 6.00 ± 0.11 and 7.78 ± 0.04 for rodA and HF183 genetic markers, for E. coli and human host associated Bacteroides, respectively, indicating about 5 % sewage content. SourceTracker analysis of sequencing data attributed 72–77 % of bacteria in the downstream section of the river during a storm event to CSO discharge sources, versus only 4–6 % to rural upstream sources. Data from sixteen summer sampling events in a public park exceeded various guideline values for recreational water quality. Quantitative microbial risk assessment (QMRA) predicted a median and 95th percentile risk of 0.03 and 0.39, respectively, of contracting a bacterial gastrointestinal disease when wading and splashing around in the Ouseburn. We show clearly why microbial water quality should be monitored where rivers flow through public parks, irrespective of their bathing water designation.

Validation of an isotope dilution mass spectrometry (IDMS) measurement procedure for the reliable quantification of steroid hormones in waters.

Reliable data are compulsory to efficiently monitor pollutants in aquatic environments, particularly steroid hormones that can exert harmful effects at challenging analytical levels below the ng L-1. An isotope dilution two-step solid-phase extraction followed by an ultra-performance liquid chromatography separation coupled to tandem mass spectrometry (UPLC-MS/MS) detection method was validated for the quantification of 21 steroid hormones (androgens, estrogens, glucocorticoids, and progestogens) in whole waters. To achieve a realistic and robust assessment of the performances of this method, the validation procedure was conducted using several water samples representative of its intended application. These samples were characterized in terms of concentration of ionic constituents, suspended particulate matter (SPM), and dissolved organic carbon contents (DOC). For estrogens that are part of the European Water Framework Directive Watchlist (17beta-estradiol and estrone), the performances met the European requirements (decision 2015/495/EU) in terms of limit of quantification (LQ) and measurement uncertainty. For 17alpha-ethinylestradiol, the challenging LQ of 0.035ng L-1 was reached. More generally, for 15 compounds out of 21, the accuracy, evaluated in intermediate precision conditions at concentrations ranging between 0.1 and 10ng L-1, was found to be within a 35% tolerance. The evaluation of the measurement uncertainty was realized following the Guide to the expression of Uncertainty in Measurement. Finally, a water monitoring survey demonstrated the suitability of the method and pointed out the contamination of Belgium rivers by five estrogens (17alpha-ethinylestradiol, estriol, 17alpha-estradiol, 17beta-estradiol, and estrone) and three glucocorticoids (betamethasone, cortisol, and cortisone) which have been up to now poorly documented in European rivers.

Using environmental DNA metabarcoding to monitor fish communities in small rivers and large brooks: Insights on the spatial scale of information

Monitoring fish communities is central to the evaluation of ecological health of rivers. Both presence/absence of fish species and their relative quantity in local fish assemblages are crucial parameters to measure. Fish communities in lotic systems are traditionally monitored via electrofishing, characterized by a known limited efficiency and high survey costs. Analysis of environmental DNA could serve as a non-destructive alternative for detection and quantification of lotic fish communities, but this approach still requires further insights in practical sampling schemes incorporating transport and dilution of the eDNA particles; optimization of predictive power and quality assurance of the molecular detection method. Via a controlled cage experiment, we aim to extend the knowledge on streamreach of eDNA in small rivers and large brooks, as laid out in the European Water Framework Directive's water typology. Using a high and low source biomass in two river transects of a species-poor river characterized by contrasting river discharge rates, we found strong and significant correlations between the eDNA relative species abundances and the relative biomass per species in the cage community. Despite a decreasing correlation over distance, the underlying community composition remained stable from 25 to 300 m, or up to 1 km downstream of the eDNA source, depending on the river discharge rate. Such decrease in similarity between relative source biomass and the corresponding eDNA-based community profile with increasing distance downstream from the source, might be attributed to variation in species-specific eDNA persistence. Our findings offer crucial insights on eDNA behaviour and characterization of riverine fish communities. We conclude that water sampled from a relatively small river offers an adequate eDNA snapshot of the total fish community in the 300–1000 m upstream transect. The potential application for other river systems is further discussed.

Biological survey of lakes and reservoirs from Sardinia and Piedmont (Italy), a georeferenced dataset from the project LIFE INHABIT

We report a georeferenced dataset of a biological survey carried out in lakes and reservoirs in Piedmont and Sardinia regions (Italy), that includes fish fauna, macroinvertebrates, macrophytes, and phytoplankton. This survey was carried out to test the standardised protocols adopted with the National Decree 260/210 by the Italian Ministry of the Environment, Land and Sea for the assessment of the ecological status of lakes and the ecological potential of reservoirs for satisfying the requirements of the European Water Framework Directive (WFD) 2000/60/EC. Occurrence data have been uploaded to the Global Biodiversity Information Facility (GBIF).

Effects of multiple stressors on benthic invertebrates using Water Framework Directive monitoring data

Multiple stressors affect freshwater systems and cause a deficient ecological status according to the European Water Framework Directive (WFD). To select effective mitigation measures and improve the ecological status, knowledge on the stressor hierarchy and individual and joined effects is necessary. However, compared to common stressors like nutrient enrichment and morphological degradation, the relative importance of micropollutants such as pesticides and pharmaceuticals is largely unaddressed. We used WFD monitoring data from Saxony (Germany) to investigate the importance of 85 environmental variables (including 34 micropollutants) for 18 benthic invertebrate metrics at 108 sites. The environmental variables were assigned to five groups (natural factors, nutrient enrichment, metals, micropollutants and morphological degradation) and were ranked according to their relative importance as group and individually within and across groups using Principal Component Analyses (PCAs) and Boosted Regression Trees (BRTs). Overall, natural factors contributed the most to the total explained deviance of the models. This variable group represented not only typological differences between sampling sites but also a gradient of human impact by strongly anthropogenically influenced variables such as electric conductivity and dissolved oxygen. These large-scale effects can mask the individual importance of the other variable groups, which may act more specifically at a subset of sites. Accordingly, micropollutants were not represented by a few dominant variables but rather a diverse palette of different chemicals with similar contribution. As a group, micropollutants contributed similarly as metals, nutrient enrichment and morphological degradation. However, the importance of micropollutants might be underestimated due to limitations of the current chemical monitoring practices.

Factors influencing submerged macrophyte presence in fresh and brackish eutrophic waters and their impact on carbon emissions

In agricultural landscapes of North-Western Europe, the majority of water bodies do not meet the targets set by the European Water Framework Directive due to a lack of submerged macrophytes and associated biodiversity. These eutrophic waters can also be a substantial source of methane (CH4) and carbon dioxide (CO2) to the atmosphere. Here we present a two-year field experiment on the island of Goeree-Overflakkee (southwest Netherlands), conducted in six drainage ditches varying in salinity, where we monitored four permanent plots per ditch and varied the presence of both fish and macrophytes. We aimed to: 1) investigate factors limiting submerged macrophyte growth, focussing on exclusion of grazing pressure and bioturbation by fish; and 2) quantify the CO2 and CH4 emission under these conditions. Even in highly eutrophic, semi turbid ditches with fluctuating salinity levels and sulphide presence in the root zone, submerged macrophytes established successfully after introduction when the influence of grazing and bioturbation by fish was excluded. In the exclosures, diffusive CH4 and CO2 emissions, but not ebullitive CH4 emissions were significantly reduced. The spontaneous development of submerged macrophytes in the exclosures without macrophyte introduction underlined the effect of grazing and bioturbation by fish and suggest that abiotic conditions did not hamper submerged macrophyte development. Our results provide important insights into the influential factors for submerged macrophyte development and potential for future management practices. Large-scale fish removal may stimulate submerged macrophyte growth and reduce methane emissions, albeit that the macrophyte diversity will likely stay low in our study region due to fluctuating salinity and eutrophic conditions.

Moving forward to achieve the ambitions of the European Water Framework Directive: Lessons learned from the Netherlands

The restoration and preservation of freshwater ecosystems is one of the prerequisites for a sustainable and fair future for all and therefore part of the United Nations Sustainable Development Goals (SDG 6). However, countries worldwide are facing a challenge to achieve this ambition by 2030. This paper focuses on the legal and governance challenges faced in the European context with regard to achieving water quality ambitions, using experiences from the Netherlands as a case study. Although many EU Member States (MS) are facing a challenge to meet the ambitions set by the Water Framework Directive (WFD) in 2027, literature on effectiveness of governance approaches in terms of actual water quality improvement, seems to be scarce. Based on interviews, a survey, expert panel discussions and literature we show that in the Netherlands, an important problem is that stakeholders, also within organisations, have different views on ambitions, achievements and necessary follow-up actions. This is problematic because for realising the water quality ambitions, cross-sectoral cooperation (e.g. from agriculture and spatial development) as well as strengthened interlinkages between these related policy fields is crucial. Moreover, there is a tendency to stick to the status quo. In order to increase effectiveness, a better understanding of the underlying mechanisms for this lock-in will be necessary. This will enable the development of practical tools and instruments to support cross-sectoral and multi-level collaboration.The sectoral implementation of the WFD in the Netherlands was chosen by many other MS, resulting in similar cross-sectoral challenges as we found in the Netherlands. Insight into how other MS deal with lock-in situations is needed to develop pathways to achieving WFD ambitions.

Addressing diffuse water pollution from agriculture: Do governance structures matter for the nature of measures taken?

Nutrient pollution of freshwaters from agriculture is a key barrier to achieving the water quality goals of the European Water Framework Directive (WFD). Governance research suggests that governance structures can support the planning of water quality measures. However, it is widely unclear how specific governance structures affect the actual nature of practical measures taken for addressing the “wicked problem” of diffuse nutrient pollution. This study analyses how the extent of consensual policy styles, organizational and program integration, participatory governance, and the capacities of public authorities are related to the substance of practical measures taken (effect-vs. source-based measures) and the choice of policy instruments (e.g., sermons, carrots, sticks). Based on a comparative case study design including six country cases, document analyses, and expert interviews, we find no clear-cut relationships between the country's governance structures and the types of measures chosen or any trend of a combined effect. This suggests that, in the case of the WFD, governance structures are less important than expected or that different governance structures compensate for the effects on the level of practical measures taken and policy instruments chosen. These results question the dominant assumption that these governance structures matter (a lot) in wicked problem solving and may hint to additional context factors these governance structures are embedded in.

Benthic Macroinvertebrate Multimetric Index for River (BMIR): Development of a multimetric index based on benthic macroinvertebrates for rivers in Türkiye

Stream types determined according to altitude, slope and alkalinity in six different hydrobiogeographic regions of Türkiye were taken as the basis of the study. In line with the European Water Framework Directive, a macroinvertebrate based multimetric method was tested for Turkish rivers as a potential assessment. In this study, benthic macroinvertebrate data (3502 samples obtained from 1925 stations with reference points) were used to create a multimetric index for all river types in the hydrobiogeographic regions of Türkiye. Nine (9) biological metrics were evaluated and index development criteria were chosen to capture meaningful results at the ecosystem, community and individual levels. The metric combinations were chosen to show the best distinction between areas with no or only very minor anthropogenic disturbances and stressed areas (with discrimination efficiency values). The multimetric index, which includes three different metrics from three different metric categories, distinguishes reference or slightly distorted areas from stressed areas with an efficiency close to 100%. Index values were divided at a five-scale system between one (High) and zero (Bad) for biological evaluation. Further testing and research can be done so that the index will provide a more useful result as a bioassessment tool for decision makers in hydrobiogeographic regions. Also, the index can provide a basis for methods by which river status is assessed based on stress factors.

Донная фауна и оценка экологического состояния нижнего участка р. Ангары

On the Angara River there is a reservoirs cascade of four hydroelectric power stations, and in the lower reaches it is planned to build the Nizhneboguchanskaya HPS. On the other hand, at present there is a significant gap in the studies of the Angara lower section, especially in zoobenthos. The material for the study was zoobenthos samples taken in the coastal zone in August 2022 at 11 river stations in a section from 445 km to 9 km from the mouth. Biotopes of zoobenthos are represented mainly by pebble-sandy soil with varying degrees of silting. The benthic fauna of the Angara River was gammarid-chironomid in nature; oligochaetes were found everywhere, but in small numbers. 87 species and taxa of a higher rank had been identified, the largest number of species (37) was noted among the chironomid larvae of Orthocladiinae and Chironominae. The quantitative advantage (more than 60% of the abundance and biomass) belonged to amphipods. Chironomids predominated over amphipods only on silty bottoms; in the river section, in general, they accounted for 24% of the abundance and 10% of the biomass of benthic communities. The Shannon species diversity index was relatively low and amounted to 2.3 bit/ind. general in the section. The lower reaches of the river were characterized by the highest species diversity, but the lowest number of benthic invertebrates. The total number of zoobenthos in the studied area was 2,9 thousand ind/m2, biomass – 14,6 g/m2, in the lower reaches of the river the number decreased to 1.7 thousand ind/m2, biomass – up to 4 g/m2. An integrated approach was used to assess the water quality of the Angara benthic communities, that includes the analysis of 8 bioindication indices: Goodnight (G), Woodiwiss (TBI) and saprobity (S) indices (recommended by the Russian regulatory document); indices FBI, BMWP, ASPT (recommended by the European Water Framework Directive); the Balushkina chironomid index (K) and the Shannon species diversity index. The fundamental criterion for the selection of indices was the level of development of indicator taxa. The complex assessment revealed the trend of improving water quality to the mouth of the river. This trend is expressed in the consistent dynamics of the TBI, BMWP, ASPT indices, which can be recommended for assessing the ecological state of the Angara River and other watercourses in the region. The water quality corresponded to Class III (Polluted) with a tendency to improve at the mouth to Class II (Slightly polluted).

Nature-based solutions for nutrient pollution control in European agricultural regions: A literature review

There is an increasing attention on Nature-based Solutions (NBS) to address social and environmental challenges in Europe, including the control of excess nutrients conveyed by agricultural regions. Indeed, the excess of nutrients has been recognized as one of the main reasons of failure to achieve a good ecological status of water bodies, according to the European Water Framework Directive 2000/60/EC. In this study we consider NBS to control two main sources of nutrient pollution in agricultural regions: excess manure from intensive livestock breeding, and diffuse pollution due to fertilizers applied on fields. The NBS typically adopted to address these two sources of pollution are wetlands in addition, for diffuse pollution, to vegetated drainage ditches and buffer strips. From a review of 767 peer review articles, we built a dedicated dataset including a total number of 444 NBS cases. These were analysed to obtain an overview of: (i) the range of climate, landscape and design variables under which the above typologies of NBS have been implemented; (ii) their performances for nutrient pollution control, in terms of removal efficiency on concentrations and mass load removal per unit of surface; (iii) the relationships between landscape, climate, and design variables and treatment performance. The results are presented in order to guide future planning of NBS for pollution control in European agricultural regions.

Fish tissue conversion factors for mercury, cadmium, lead and nine per- and polyfluoroalkyl substances for use within contaminant monitoring

Fish tissue levels have to comply with environmental quality standards (EQSs) within the European Water Framework Directive. However, within monitoring, contaminants are sometimes measured in a different tissue than the tissue for which the environmental (whole fish) or human (fillet (equivalent to muscle tissue)) quality standard is set. Tissue conversion factors (k), describing the relationship between concentrations in different tissues, can be used to obtain a quality standard for the appropriate tissue. Several different approaches have been suggested for the calculation of k. For monitoring purposes, we propose the use of a simple, easy reproducible approach that assumes proportionality between two tissue, or tissue and whole fish, concentrations. This allows for an easy comparison of studies and adoption of ks into independent monitoring programs. Here, we determined ks for three metals (mercury (Hg), lead (Pb), cadmium (Cd)) and nine per- and polyfluoroalkyl substances (PFAS) including perfluorooctanesulfonic acid (PFOS) across six marine and freshwater fish species from Northern European lakes and the Baltic Sea. We found significant species differences for Hg for kmuscle/whole fish, for Cd and Pb for kliver/whole fish and for Cd for kliver/muscle. For perfluoroalkyl carboxylic acids (PFCA), we found a chain length dependence with lowest kliver/muscle at low and high chain lengths (C8, C13) and highest for median chain lengths (C9-C12). Further, there were differences between fish species with kliver/muscle for PFOS almost doubling from eelpout (10.3) to herring (19.2) and increasing up to a factor 4 between eelpout and herring for other PFASs. FOSA had two distinctive groups, herring with a kliver/muscle of 48.7 and a second group with ks of 2.3 to 5.9 for all other fish species. Our results suggest that differences in the tissue somatic index, and contaminant uptake, tissue transfer and metabolism result in the need for species-specific ks within monitoring.

Ecotoxicological tools in support of the aims of the European Water Framework Directive: A step towards a more holistic ecosystem-based approach

The Water Framework Directive (WFD) aims to attain ‘good quality’ status for all European water bodies through the achievement of good ecological status. To this purpose, the WFD advocates the creation of cost-effective monitoring tools to deliver appropriate data that help to create links between chemical and ecological indicators, as those from ecotoxicological research. Here, it was evaluated whether the integration of ecotoxicological tools, as bioassays and biomarkers, did (or did not) strengthen the robustness of the assessment of the ecological status obtained through well stablished biotic indices in two Atlantic estuaries. For that, a battery of in-situ bioassays, including five macroinvertebrate species (the crab Carcinus maenas, the amphipod Echinogammarus marinus, the isopod Cyathura carinata, the snail Peringia ulvae and the polychaete Hediste diversicolor, each one providing complementary information regarding key ecological functions) and a set of biomarkers, was used. In addition, the concentrations of heavy metals in sediments, and in macroalgae (Fucus), were determined, along with sediment granulometric, water physicochemical and nutrients characterization. We show that by interpreting the values of all indicators together, along with environmental components, it is possible to perform a more holistic description of the quality status of a waterbody – and, to begin to allude to factors limiting that quality. Ecotoxicological tools (in situ bioassays and biomarkers) appear to provide an added value of useful information for monitoring programmes regarding the true state - within which, both known and unknown contaminants are potentially present at concentrations sufficient to cause biological effects. Our results support the use of in situ bioassays and biomarkers within protocols aimed at fulfilling the goals of the WFD. In doing so, more complete and informative assessments of the ecological quality status of water bodies can take place.

Prediction of ecological status of surface water bodies with supervised machine learning classifiers

Ensuring a good ecological status of water bodies is one of the key challenges of communities and one of the objectives of the European Water Framework Directive. Although recent works identified the most significant stressors affecting the ecological quality of rivers, the ability to predict the overall ecological status of rivers based on a limited amount of easily accessible geospatial data has not been investigated so far. Most of the analyses focus on detailed local modelling and measurements which cannot be systematically applied at regional scales for the purposes of water resources management. The aim of this work is to understand the capabilities of five supervised machine learning classifiers of predicting the ecological status of rivers based on land use, climate, morphology, and water management parameters extracted over the river catchments corresponding to the ecological monitoring stations. Moreover, the performances of machine learning classifiers are compared to the results of the canonical correlation analysis. The method is applied to 360 catchments in Tuscany (central Italy) with a median size of 33.6 km2 and a Mediterranean climate. The results show (i) a significant correlation of ecological status with summer climate (i.e., maximum temperatures and minimum precipitation), land use and water exploitation, (ii) an 80 % precision of Random Forest algorithm to predict ecological status and (iii) higher capability of all classifiers to predict at least good ecological status. In perspective, such predictive capabilities can support decision making in the land and water resources management and highlight strategies for river eco-hydrological conservation.

Performance of Micropollutant Removal during Wet-Weather Conditions in Advanced Treatment Stages on a Full-Scale WWTP

The reduction of organic micropollutants (OMP) in rivers, lakes and groundwater is an essential legal obligation of the European Water Framework Directive. Since OMP treatment in full-scale wastewater treatment plants (WWTPs) is not state of the art yet, there is little knowledge regarding removal performances, in particular during wet weather. We aimed to contribute to filling this knowledge gap by providing insights from a German case study. On-site measurements were conducted to investigate the impact of rain events on OMP removal with activated carbon processes using powdered activated carbon (PAC) and granular activated carbon (GAC). The study focused on 26 OMPs with different entry paths in the combined sewer system (CSS) and various physico-chemical properties. The monitored OMPs showed higher mass loads during wet weather at all sampling points: effluent of the secondary clarifier, effluent of the PAC treatment stage, and effluent of the GAC filter. As a result of shortened hydraulic retention time (HRT) due to rain events, the overall OMP removal was significantly lower (42% PAC and 46% GAC) than during dry weather (68% PAC and 62% GAC). In order to achieve constant removal rates during all weather conditions, the critical process control parameters are currently being investigated in ongoing studies.

Negative influence of a threatened species on ecological status classification: A case study of the influence of European eel within the Swedish fish index VIX

Biological indicators are important quality elements for classification of ecological status of water bodies according to the European Water Framework Directive. Multimetric indices are commonly regarded as robust and reliable indicators of human impact and are often used as quality elements. In fish-based indices, species are often grouped into guilds based on general tolerance to common anthropogenic pressures, with higher proportion of tolerant species being indicative of degraded systems. Within the Swedish electrofishing index VIX, the critically endangered European eel Anguilla anguilla (L.) is classified as a tolerant indicator species, and it therefore has a negative effect on classified ecological status. The scientific literature, however, suggests that eels are not generally tolerant and they benefit from similar environmental conditions as many insensitive species. VIX has been criticized for being too sensitive to the presence of eel in catch data, leading to low status classifications when eels are caught in the monitoring surveys. In a case study using manipulations of historical electrofishing data, we assessed the influence of eel presence and abundance on the ecological status classification as determined by VIX. We demonstrate that reduction of eels in survey data have positive effects on the classified status, in many cases substantial effects. An increase of eels in the data had the reverse effect. Mere presence of eel had a strong negative effect, which is problematic if the aim is to increase the endangered eel population. Given the Swedish classification system where the quality element indicating the worst status is decisive, the classified ecological status of Swedish rivers can theoretically be improved by management actions disfavouring eel, unless the results from VIX are carefully evaluated by experts. Along the same lines, measures implemented with an aim to increase the endangered eel population will lead to a decrease in assessed ecological status of Swedish rivers. Our conclusion is that the usage of VIX within Swedish water management is problematic and needs revision. From a broader perspective, the classification of species as generally tolerant need to be approached with great caution when developing new indices for assessing ecological status and integrity.

Towards a functional assessment of stream integrity: A first large-scale application using leaf litter decomposition

• Litter decomposition exhibits large variability at the regional scale (83 streams). • Litter decomposition does not correlate with the European WFD structural indicators. • Functional and structural indicators are complementary. • A grid is given to translate decomposition rates into functional quality classes. There is increasing recognition that indicators of ecosystem functioning are needed to improve current stream monitoring schemes. However, to date, no attempt has been made to include functional metrics in large-scale routine monitoring programs under the European Water Framework Directive (WFD). One reason is the uncertainty if functional indicators really carry new and independent information about stream status or, to the contrary, remain broadly redundant with existing indicators of biological stream quality (based on stream communities). A second reason is that, despite increasing scientific knowledge on how anthropogenic pressures influence ecosystem process rates, no ‘ready for use’ tool is available to translate them into stream ecosystem status. Litter decomposition probably ranges among the most documented stream ecosystem processes, and its potential for bioindication has been repeatedly demonstrated during the past decade. Here we report an extensive comparison of routine French structural indicators (I 2 M 2 , IBGN, IBD) with alder litter (microbial and total) decomposition rates in 83 streams located in south-western France. Expectedly, microbial decomposition rates were positively correlated with fungal biomass and activity (conidial production rate), while total and invertebrate-driven decomposition rates increased together with detritivore density and diversity in litter bags. By contrast, correlations between litter decomposition rates and routine structural indicators were clearly weak (Spearman’s ρ < 0.20), providing evidence that functional indicators bring new information. We devised a new interpretation grid to translate litter decomposition rates into stream ecological quality in a WFD-compatible design. This system considers the litter decomposition rates measured in both coarse (total decomposition) and fine (microbial decomposition) mesh bags as uncorrelated metrics of ecosystem functioning ( P = 0.898). Streams are considered functionally impaired when total and/or microbial decomposition rates are either higher or lower than in a reference condition. Applying our classification system to the 83 study sites allowed to assign them to 5 functional quality classes: bad (4 streams), poor (26), fair (29), good (21) and high (3). This classification did not match the classes obtained by conventional WFD structural indicators, reflecting that both functional and structural indicators are needed to obtain a comprehensive assessment of stream ecosystem integrity.

Occurrence and distribution of persistent organic pollutants in the liver and muscle of Atlantic blue sharks: Relevance and health risks

Blue shark score among the most abundant, widely distributed and worldwide consumed elasmobranchs. In this work contents of PCBs, PCDD/Fs and PBDEs were studied by means of GC-HRMS in muscle and liver of sixty blue sharks from the North East Atlantic sampled in 2019. Concentrations relatively similar were found for PCBs and PCDD/Fs in comparison with those in Atlantic specimens from the same area sampled in 2015. In contrast, PBDE loads doubled, likely mirroring the increased environmental presence of these pollutants. This, together with the different congener profiles reported for the same species in other geographical areas, highlighted the blue shark's potential as bioindicator of the degree and fingerprints of regional pollution by POPs. Interesting dissimilarities between muscle and liver concentrations were detected, most likely ascribed to distinct toxicokinetics involved for the different pollutants. Whereas most POPs preferentially accumulated in liver, some did the opposite in muscle. BDE-209 was the most prominent example, being almost negligible its presence in liver (0.3%) while accounting for ca. 14% of the total PBDE content in muscle. Different findings in this regard described for other shark species call for focused research to ascertain the role of the species in this apparent favored metabolization of BDE-209 in the liver. From a consumption perspective, the concentrations found in muscle -the most relevant part in the human diet-for PCBs and dioxin-like POPs were below the EU maximum allowed levels in foodstuff. Conversely, in liver about 58% and 78% of samples overpassed the European levels for tolerable intake of i-PCBs and dioxin POPs, respectively. Concentrations of PBDEs exceeded EQS (0.0085 ng/g w.w.) established by the European Water Framework Directive in 100% and 92% of liver and muscle samples, respectively, which adds to the open debate of such as a reduce value for this current EQS.

Spring waters as an indicator of nitrate and pesticide pollution of rural watercourses from nonpoint sources: results of repeated monitoring campaigns since the early 2000s in the low mountain landscape of Saarland, Germany

BackgroundSpring waters, which are fed mainly by near-surface groundwater, provide a comprehensive picture of emissions of nitrate and other pollutants caused by the type and intensity of land use in the topographic catchment area. One aim of this study was to develop a model for predicting the contribution of nonpoint-source inputs to the nitrate load of small- and medium-sized watercourses based on the type of agricultural use in the catchment areas.MethodsFifty-five springs in the German Land Saarland and the adjacent Rhineland-Palatinate were monitored for pollutants during three monitoring periods of at least 12 months between 2000 and 2019. The catchment areas are representative of the natural regions in the study area and are outside the influence of settlements and other developments. In addition to nitrate and other physicochemical parameters, 25 agriculturally impacted springs were screened for pesticides and their metabolites.ResultsSince the first measurements were taken in 2000, the vast majority of agriculturally impacted springs have consistently exhibited high nitrate concentrations of between 20 and 40 mg/L NO3−. Springs not influenced by agriculture contained an average of 3.6 mg/L nitrate. The extreme values observed in the early 2000s decreased to the limit value of 50 mg/L, but most of the springs with moderate levels exhibited an increase to approximately 30 mg/L. The number of pesticidal agents detected in the spring waters demonstrated a clear correlation with the watershed’s amount of arable land and the nitrate content detected. Moreover, we found a highly significant correlation between nitrate content and the share of cropland in the catchment area. From this, we derived a regression model that could be used to quantify the share of nitrate pollution attributable to nonpoint-source inputs for larger catchments in the region under investigation.ConclusionNitrate discharged from farmland has not decreased since the European Water Framework Directive (EU WFD) entered into force. At the historically extremely heavily polluted sites, measures have been implemented that have led to compliance with the limit value of the Nitrate Directive. However, below this limit, nitrate levels have increased significantly almost everywhere in the last two decades. We therefore recommend introducing stricter requirements for official water pollution control, such as the marine ecological target value.

Summer greenhouse gas fluxes in different types of hemiboreal lakes

Lakes are considered important regulators of atmospheric greenhouse gases (GHG). We estimated late summer open water GHG fluxes in nine hemiboreal lakes in Estonia classified under different lake types according to the European Water Framework Directive (WFD). We also used the WFD typology to provide an improved estimate of the total GHG emission from all Estonian lakes with a gross surface area of 2204 km2 representing 45,227 km2 of hemiboreal landscapes (the territory of Estonia). The results demonstrate largely variable CO2 fluxes among the lake types with most active emissions from Alkalitrophic (Alk), Stratified Alkalitrophic (StratAlk), Dark Soft and with predominant binding in Coastal, Very Large, and Light Soft lakes. The CO2 fluxes correlated strongly with dissolved CO2 saturation (DCO2) values at the surface. Highest CH4 emissions were measured from the Coastal lake type, followed by Light Soft, StratAlk, and Alk types; Coastal, Light Soft, and StratAlk were emitting CH4 partly as bubbles. The only emitter of N2O was the Alk type. We measured weak binding of N2O in Dark Soft and Coastal lakes, while in all other studied lake types, the N2O fluxes were too small to be quantified. Diversely from the common viewpoint of lakes as net sources of both CO2 and CH4, it turns out from our results that at least in late summer, Estonian lakes are net sinks of both CO2 alone and the sum of CO2 and CH4. This is mainly caused by the predominant CO2 sink function of Lake Peipsi forming ¾ of the total lake area and showing negative net emissions even after considering the Global Warming Potential (GWP) of other GHGs. Still, by converting CH4 data into CO2 equivalents, the combined emission of all Estonian lakes (8 T C day−1) is turned strongly positive: 2720 T CO2 equivalents per day.