Physico-chemical Quality Elements Research Articles

Bayesian inference of physicochemical quality elements of tropical lagoon Nokoué (Benin).

In view of the very strong degradation of aquatic ecosystems, it is urgent to set up monitoring systems that are best able to report on the effects of the stresses they undergo. This is particularly true in developing countries, where specific and relevant quality standards and funding for monitoring programs are lacking. The objective of this study was to make a relevant and objective choice of physicochemical parameters informative of the main stressors occurring on African lakes and to identify their alteration thresholds. Based on statistical analyses of the relationship between several driving forces and the physicochemical parameters of the Nokoué lagoon, relevant physicochemical parameters were selected for its monitoring. An innovative method based on Bayesian statistical modeling was used. Eleven physicochemical parameters were selected for their response to at least one stressor and their threshold quality standards also established: Total Phosphorus (<4.5mg/L), Orthophosphates (<0.2mg/L), Nitrates (<0.5 mg/L), TKN (<1.85 mg/L), Dry Organic Matter (<5 mg/L), Dissolved Oxygen (>4 mg/L), BOD (<11.6 mg/L), Salinity (7.6 ‰), Water Temperature (<28.7°C), pH (>6.2), and Transparency (>0.9 m). According to the System for the Evaluation of Coastal Water Quality, these thresholds correspond to "good to medium" suitability classes, except for total phosphorus. One of the original features of this study is the use of the bounds of the credibility interval of the fixed-effect coefficients as local weathering standards for the characterization of the physicochemical status of this anthropized African ecosystem.

Assessing the effectiveness of management measures in the Ria Formosa coastal lagoon, Portugal

The Ria Formosa is an important transitional and coastal lagoon on the south coast of Portugal that provides valuable ecosystem services. The lagoon is a protected area under national and international conventions. There is a great potential for Blue Growth sectors, such as aquaculture and coastal tourism, but these rely on good water quality. European environmental legislation, such as the Water Framework Directive, requires member states, such as Portugal to implement management measures if a surface water body is not of good ecological status. This work addresses the effectiveness of management measures, such as wastewater treatment plant implementation and dredging, on the water quality of the Ria Formosa coastal lagoon system. This is an important social-ecological issue, since management measures can be very expensive. The ecological status of Ria Formosa was evaluated, according to the physico-chemical and biological quality elements of the Water Framework Directive. The main indicators were the physico-chemical quality elements of nutrient and oxygen condition, and the biological quality element chlorophyll a, as a proxy for phytoplankton biomass, under the Water Framework Directive. The data for these quality elements from the Ria Formosa were analyzed for consistency with the classification for the Water Framework Directive water bodies. The data after the implementation of management measures was compared with historical data to evaluate if these measures had been effective. The relation between nutrient pressures, meteorological and hydrological conditions was addressed, especially rainfall and runoff. Results showed a decrease in nutrient concentration after the management interventions, despite the increase of population and intensifying agriculture in the catchment. The Ecological Status is spatially variable with an overall moderate status, indicating the need for further management measures. There is a significant reduction in nutrient pressure on the lagoon during drought years. This indicates that climate change may alter the structure and function of the lagoon in the future.

A New Multi-Index Method for the Eutrophication Assessment in Transitional Waters: Large-Scale Implementation in Italian Lagoons

Eutrophication represents one of the most impacting threats for the ecological status and related ecosystem services of transitional waters; hence, its assessment plays a key role in the management of these ecosystems. A new multi-index method for eutrophication assessment, based on the ecological index MaQI (Macrophyte Quality Index), the trophic index TWQI (Transitional Water Quality Index), and physicochemical quality elements (sensu Dir. 2000/60/EC), was developed including both driver and impact indicators. The study presents a large-scale implementation of the method, which included more than 100 Italian lagoon sites, covering a wide variability of lagoon typologies and conditions. Overall, 35% of sites resulted in eutrophic status, 45% in mesotrophic, and 25% in oligotrophic status.

Impacts of Extreme Weather Events on Hydromorphology of UK Rivers

In this study, we assessed the effects of extreme weather events on Hydro-morphological Quality Elements in rivers of the United Kingdom alongside other pressures that will provide significant challenges for the implementation of the Water Framework Directive in the UK in terms of cost-effectiveness and sustainability. While observed meteorological data and river data sets were used for assessing changes in river systems and weather patterns, for future assessments, UK Climate Projections 2018 data was used. The studies in the literature have shown that during periods of extreme events, the river hydro-morphology is affected especially in terms of river flows, sediments and riparian zones such as draughts, and intense and heavy rainfall leading to reduced or exceptionally high flow respectively. Reduced flows can lead to the loss of habitat of aquatic organisms and an increase in fish deaths. Whilst increased river flows lead to changes of the hydro-morphology of rivers including changes to sediment dynamics and channels, rivers are also under negative effects of anthropogenic hydro-morphological pressures such as building dams and water abstractions. Furthermore, changes in river hydro-morphology can cause other problems such as increasing water temperature and decreasing dissolved oxygen, and thereby degrading Biological Quality Elements and Physico-Chemical Quality Elements. To deal with and mitigate these problems, a holistic view of water policy that considers climate change projections, reduces water demand, changes agricultural and urban land use practices, improves water availability and quality is required.

Diatom diversity and ecological status of the Lasovacka and Lenovacka streams near Zajecar: Consideration of WFD implementation in Serbia

The development and improvement of the monitoring system of rivers according to the requirements of the Water Framework Directive (WFD) is essential for all European states because assigning a wrong ecological status class (misclassification) to a water body can have significant economic consequences. In order to point out some of the key issues of WFD implementation in Serbia, we conducted a one-year study of the composition and abundance of diatoms in the phytobenthos in two streams, the Lasovacka and Lenovacka, in eastern Serbia. The physicochemical quality elements were also used in the assessment of their ecological status. The diatom community exhibited a higher species richness in the Lasovacka (88 taxa) than in the Lenovacka stream (63 taxa). Such a detailed study enabled us to record some of the rare taxa, e.g. Caloneis budensis in the Lasovacka, which was the first finding of this species in Serbia. The Lasovacka and Lenovacka streams were downgraded to moderate and poor ecological status, respectively, because of the high nitrogen load. Since the monitoring results based on the diatom indices resulted in the assignment of two streams to a good ecological status, the possible reason for the mismatch between the biological and physicochemical quality elements could be due to the lack of analysis of benthic invertebrate fauna or the application of diatom indices that are insufficiently sensitive to the specific environmental pressure. The results of this study show that conducting a comprehensive ecological investigation of rivers within the framework of the WFD in Serbia is urgently needed.

Accounting for ecosystem services in water quality standards compliance.

O the past decade, legislation to improve water quality across Europe and the United States has focused on returning surface waters to “reference” conditions, defined as a state in the past or present, corresponding with minimal anthropogenic pressures (i.e., without the effects of industrialization, urbanization or intensive agriculture and, with only minor modification of physico-chemistry, hydromorphology and biology). Much of this legislation is designed to address eutrophication, nuisance algal growth and water-body hypoxia, which are a pervasive source of water quality impairment. Eutrophication has profound implications for environmental and human health, and water security. In the E.U., the Water Framework Directive (WFD, 2000), now mandates that all surface waters (except those subject to specific derogations) must achieve “Good Ecological Status” (GES) by 2015. Good Ecological Status is defined as deviating only slightly from “undisturbed” reference conditions, based on an integrated assessment of water-body ecological condition, including biological, hydromorphological and physicochemical quality elements. Here, we present data which show that large areas of Europe are currently failing to achieve GES (Figure 1). We argue that reference conditions, reflecting an undisturbed nearpristine state, are unlikely to be achievable over WFD time scales, for many watersheds which provide the vital ecosystem services, such as food production and wastewater disposal, and water purification and treatment. These ecosystem services support communities and the economic activity upon which society depends. We propose that accounting for watershed ecosystem services, along with a directional approach based on “gap closure” between present conditions and desired waterquality “reference” end points, offers a way forward for continued improvement in the quality and ecology of surface waters. In 2012, 12 years after the WFD became law, only one river basin district within the EU, in remote and sparsely populated subarctic Finland, achieved GES in more than 90% of its water bodies (Figure 1). Across large areas of the lowlands of central and northwestern Europe, which support large urban centers and productive agricultural regions, less than 30% of water bodies are achieving GES. However, the watersheds of many of these “failing” rivers provide the ecosystem services which underpin European food security and economic activity, and it is unrealistic to expect that these can be returned to nearpristine reference conditions by 2015. For example, rivers in lowland UK drain watersheds where 70% of the land area is used for agriculture, achieving over 60% self-sufficiency in UK food production. While efforts continue apace to reduce water quality impairment from farming and urban/wastewater sources, and major successes have been achieved in improving water quality over the last few decades, only 25% of all English water bodies currently achieve Good Ecological Status or Potential (the standard for water bodies that are artificial or heavily modified). Of these GES failures, 31% were attributed to agricultural and rural land management, 32% to the water industry (wastewater treatment plants); and 14% from other urban sources. Phosphorus (P) was the largest single contributor to GES failures (accounting for c. 60% of agricultural/rural and c. 50% of water industry failures). Indeed, the changes required to achieve GES, as currently defined, could have profound implications for food security, economic activity and livelihoods. It is estimated that a 50% reduction in P from agriculture would be needed across England, with implications for the intensity and scale of agricultural production at a time when food demand is rising to meet the projected growth in population of c. 20% by 2035. Moreover, given the legacy of P stored within these watersheds, it will likely take several decades to achieve these water-quality standards. As the 2015 WFD deadline approaches, “opting out” by derogating vast areas from the requirement to achieve GES by 2015, or delaying compliance until 2021 or 2027, seem to be the only options for many EU states. This risks undermining the whole WFD process, with further challenges ahead for currently failing watersheds in meeting more restrictive standards for the 2021 or 2027 compliance rounds.

Ecological Status of Rivers and Streams in Saxony (Germany) According to the Water Framework Directive and Prospects of Improvement

The Federal State of Saxony (Germany) transposed the EU Water Framework Directive into state law, identifying 617 surface water bodies (rivers and streams) for implementation of the water framework directive (WFD). Their ecological status was classified by biological quality elements (macrophytes and phytobenthos, benthic invertebrates and fish, and in large rivers, phytoplankton) and specific synthetic and non-synthetic pollutants. Hydromorphological and physico-chemical quality elements were used to identify significant anthropogenic pressures, which surface water bodies are susceptible to, and to assess the effect of these pressures on the status of surface water bodies. In 2009, the data for classification of the ecological status and the main pressures and impacts on water bodies were published in the river basin management plans (RBMP) of the Elbe and Oder rivers. To that date, only 23 (4%) streams achieved an ecological status of “good”, while the rest failed to achieve the environmental objective. The two main reasons for the failure were significant alterations to the stream morphology (81% of all streams) and nutrient enrichment (62%) caused by point (industrial and municipal waste water treatment plants) and non-point (surface run-off from arable fields, discharges from urban drainages and decentralized waste water treatment plants) sources. It was anticipated that a further 55 streams would achieve the environmental objective by 2015, but the remaining 539 need extended deadlines.

Development of Classification System and Biological Reference Conditions for Bulgarian Rivers and Lakes According to the Water Framework Directive

ABSTRACTThe study focused on sampling procedures and analysis of biological and physico-chemical quality elements (according to the EU Water Framework Directive (WFD)) and aimed at defining reference conditions and sites, maximum ecological potential, specific physico-chemical and hydromorphological conditions for assessed surface water types of “rivers” and “lakes” categories. Biological quality elements (BQE) and their metrics were selected in compliance with WFD requirements and its additional guidelines. All five compulsory BQEs were surveyed (phytoplankton, macrophyte flora, phytobenthos, macrozoobenthos, fish fauna) towards establishing rivers and lakes ecological status and potential. Current research indicates a certain necessity for integration of all assessments and analysis of ecological status/potential and their direct link to the measurement and monitoring programmes in Bulgaria.

Development of a typology for transitional waters in the Mediterranean ecoregion: The case of the islands

The European Water Framework Directive (WFD, 60EC, 2000) requires that a typology be developed at national and European level for the differentiation of ecologically distinct types within water categories. Although common typological descriptors have been defined for stream, lake and coastal areas, a typology for transitional waters has not yet been defined, and its implementation by the European countries is still under development. A set of 30 coastal lagoons from the Balearic archipelago were selected to act as case studies for the application of the WFD in the Mediterranean ecoregion. Within these systems, and according to normative definitions, we studied both biological (i.e., invertebrate and phytoplankton communities) and physico-chemical quality elements. Our objective is to propose an adequate typology for small Mediterranean coastal lagoons and to establish those criteria that, based on human pressures in the neighbouring perimeters, may allow the establishment of type-specific reference conditions. The salinity range was the only factor that enables to differentiate, in a first phase of application, ecologically relevant typologies in the studied Mediterranean islands. Other descriptors, such as tidal range and geographic localisation of the studied area had scarce relevance. The analysis of the data suggests a three-level typology for the Mediterranean coastal lagoons: oligohaline (up to 5 of salinity); mesohaline (6–26) and euhaline (>26). A total of 6 out of the 30 studied lagoons fulfil the reference criteria, covering the three salinity types proposed. The invertebrate communities showed a consistent agreement with the proposed typology, while the phytoplankton did not. Moreover, the inherent variation in the biological communities across salinity types was higher than that obtained when a subtypology based on the annual salinity range of each lagoon was applied. These results support the need for further research on the ecology of small coastal lagoons, focused on the applied aspects addressing scientific and technical implementation of WFD at the national and European levels.

Dissolved oxygen as a physico-chemical supporting element in the Water Framework Directive

For transitional and coastal waters the Water Framework Directive identifies 5 “General chemical and physiochemical elements supporting the biological elements”. The five elements are transparency, thermal conditions, oxygenation conditions, salinity and nutrient conditions. “Supporting” in the context of the directive means that the values of the physicochemical quality elements are such as to support a biological community of a certain ecological status, recognising the fact that biological communities are products of their physical and chemical environment. Physicochemical and hydromophological aspects fundamentally determine the type of water body and habitat, and hence the type specific biological community. The directive does not intended that these supporting elements should be used as surrogates for the biological elements in monitoring. The monitoring and assessment of the physical and physicochemical quality elements will support the interpretation, assessment and classification of the results arising from the monitoring of the biological quality elements. This paper considers the challenges involved in the development of oxygen standards for the directive, their relationship to the biological elements and normative conditions of the directive and to regulatory requirements.

An approach to the intercalibration of benthic ecological status assessment in the North Atlantic ecoregion, according to the European Water Framework Directive

The European Water Framework Directive (WFD) establishes a framework for the protection and improvement of transitional and coastal waters; its final objective is to achieve at least ‘good water status’ for all waters, by 2015. The WFD requires Member States (MSs) to assess the Ecological Status (ES) of water bodies. This assessment will be based upon the status of the biological, hydromorphological and physico-chemical quality elements, by comparing data obtained from monitoring networks to reference (undisturbed) conditions, and then deriving an Ecological Quality Ratio (EQR). One of the biological quality elements to be considered is the benthic invertebrate component and some structural parameters (composition, diversity and disturbance–sensitive taxa) must be included in the ES assessment. Following these criteria, several approaches to benthic invertebrate assessment have been proposed by MSs. The WFD requires that these approaches are intercalibrated. This contribution describes the comparison of the different methodologies proposed by United Kingdom, Spain, Denmark and Norway. Results show a high consistency between the approaches, both with regard to determining the EQR and boundary settings for the ES.

The water framework directive: water alone, or in association with sediment and biota, in determining quality standards?

The European water framework directive (WFD; Directive 2000/60/EC) develops the concept of ecological quality status (EcoQ) for the assessment of the quality of water masses. The EcoQ is based upon the status of biological, hydromorphological and physicochemical quality elements, with biological elements being especially important; and supported by the others. The physico-chemical elements include general variables (such as dissolved oxygen, nutrients, etc.) and specific pollutants. The former correspond to variables measured directly in the water. However, there is no indication about which matrices are to be sampled, or for which specific pollutants. In order to comprehensively assess the ecological status of aquatic systems, all the significant matrices and elements should be addressed, especially those that would most likely affect the biota of the system and those providing relevant information on impacts to them. Sediments are considered to be important in assessment of anthropogenic impacts to coastal and estuarine environments (Ridgway and Shimmield, 2002; Chapman and Wang, 2001). Similarly, biomonitors have been widely used for assessing the contamination of marine ecosystems (Cantillo, 1998; O’Connor, 1998), providing significant information on specific pollutants over relevant resolution time periods. It is highly significant that ‘water’ is referred to on 373 occasions throughout the WFD, but other matrices, such as sediment or biota (biomonitors), are mentioned explicitly only 7 and 4 times, respectively. On at least three occasions the latter two terms are used in con-