The Water Framework Directive (WFD) No. 2000/60/EC requires an integrated approach to surface water quality monitoring and evaluation. In the Czech Republic, the water status assessment is carried out according to a framework monitoring programme as required by Decree No. 98/2011, in the wording of section 21 of the Water Act and the EU-wide Environmental Quality Standards (EQS).
The current monitoring focuses on monitoring selected regulated chemicals (priority substances, priority hazardous substances and other pollutants) for which the risk to the aquatic environment is known. These are 45 priority substances and other pollutants defined at national level (about 300 in the whole EU, in the Czech Republic according to the Government Regulation No. 401/2015 Coll. and Czech standard CSN 75 7221). However, these hazardous substances constitute only a fraction of the total water toxicity and information on their presence in surface waters does not give sufficient evidence of the actual effects of the total amount of chemicals occurring in the aquatic environment, including, for example, contaminants of emerging concern (CEC), which include e.g., pharmaceuticals and cosmetic products, biocides, polar pesticides, endocrine disruptors, flame retardants, their metabolites and transformation products. In addition, substances present in the aquatic environment form mixtures the effect of which is not predictable on the basis of chemical analysis alone.
The use of EBM monitoring can help to determine the reasons for the unsatisfactory ecological status of waters and to identify other substances that may pose a threat to aquatic ecosystems and human health. The Framework Directive requires member states to set ecological objectives for each water body. If this objective is not met, the cause must be identified so that effective measures can be taken. A suitable diagnostic system is needed for this purpose, but often such a tool is not available. At present, WFD methods are used for assessing biological constituents which usually do not respond to the presence of a toxic substance in the waters, but rather to other types of stressors such as pH or low oxygen levels. The EBMs can assist in evaluating potential causes of unsatisfactory water quality. A battery of robust, standardized bioassays will allow us to determine whether the problem is actually caused by the presence of pollutants and possibly to group them according to their mechanism of action. The pollutants can then be identified by chemical analysis.
Water management institutions involved in surface water monitoring can use the proposed methodology to optimise the scope of chemical analyses and focus on the contaminants that are actually causing the risk. Based on the pollutants found, measures for their elimination can then be proposed.
The aim of the Project is to develop a water assessment methodology that will allow the identification of several groups of risky substances using four standardized ecotoxicological methods on the basis of their mechanisms of action (ecotoxicity to producers and decomposers, genotoxicity, endocrine disruption - estrogenicity). The applicability of the selected effect-based methods will be tested and verified on selected profiles in the Oder, Morava and Elbe River basins.
The effect-based methods, especially as a battery of tests based on the determination of mechanisms of action for different substances, are more indicative of water status than chemical analysis, which is limited, at best, to a few dozens of pollutants being monitored. Effect-based methods are therefore a suitable complement to routine water quality testing and should form a link between chemical and ecological assessments of water status in the future.
The methodology under development, which includes a selection of standardised ecotoxicological methods, will make effect-based monitoring available to institutions involved in surface water monitoring. The interest in this methodology has been expressed by the Water Protection Department of the Ministry of the Environment, as well as by the watershed administration enterprises Povodí Odry and Povodí Moravy and the Regional Authority of the Moravian-Silesian Region, and also institutions dealing with the surface water quality and water planning process under the Water Framework Directive. There is also cooperation with the watershed administration enterprises in water sampling and analysis of physical-chemical parameters of selected profiles.
The following outcomes are planned to be implemented within the Project and are expected to be achieved by November 2023:
Altogether 11 sites have been selected in three watersheds (the Oder, Morava and Elbe rivers) for the surface water status assessment by effect-based methods. Nine sites show long-term poor water quality, which in most cases is caused by above-limit concentrations of phosphorus and nitrogen, but also by elevated concentrations of some priority and other pollutants and metals (according to Government Regulation No. 401/2015 Coll.). Two sites were selected as reference sites with proven long-term good water quality.
Simple point water samples will be taken from these eleven sites and processed according to the TNV 75 7231 requirements. In case of positive results in the limit tests with the concentrated sample, the actual test will be performed in the appropriate concentration range. The following parameters will be evaluated: ecotoxicity, genotoxicity and endocrine disruption.
The tests were selected to cover the different toxic substances´ mechanisms of action, the high sensitivity of the tests, the speed of the experiment and the need for a relatively small amount of sample to perform the analysis.
Where relevant, the resulting effect is converted into bioanalytical BEQ equivalents (e.g., EEQ - 17ß-estradiol equivalent quotient in the YES test for the estrogenicity assessment). These data will be used for water status assessment and risk analysis. In other cases, the level of risk will be determined based on the dilution at which the positive effect of the endpoint being measured becomes apparent.
The water toxicological status assessment using effect-based methods will be compared with the water quality assessment according to the standard risk analysis of organic and inorganic pollution from data provided by the watershed administration enterprises of the Oder, Morava and Elbe Rivers.
Concentration of organic pollution samples is carried out according to TNV 75 7231. Samples are then tested by selected effect-based methods:
Those sites were selected for testing that did not meet Environmental Quality Standards (EQS) in more than five parameters. In addition to the nine profiles identified, two additional reference sites were selected to represent sites with theoretically very good water quality.
The profiles selected for water quality assessment using effect-based methods:
* Reference profiles with good water quality