Agri-drinking water quality indicators and IT/sensor techniques
|Susanne Klages, Nicolas Surdyk, Christophoros Christophoridis, Birgitte Hansen, Claudia Heidecke, Abel Henriot, Hyojin Kim, Sonja Schimmelpfennig
|»Klages, S. et al. 2018. Review report of Agri-Drinking Water quality Indicators and IT/sensor techniques, on farm level, study site and drinking water source. FAIRWAY Project Deliverable 3.1, 180 pp
Results from this research task have also been published as scientific papers:
- Klages, S.; Heidecke, C.; Osterburg, B. The Impact of Agricultural Production and Policy on Water Quality during the Dry Year 2018, a Case Study from Germany. Water 2020, 12, 1519. https://www.mdpi.com/2073-4441/12/6/1519
- Klages, S.; Heidecke, C.; Osterburg, B.; Bailey, J.; Calciu, I.; Casey, C.; Dalgaard, T.; Frick, H.; Glavan, M.; D’Haene, K.; Hofman, G.; Leitão, I.A.; Surdyk, N.; Verloop, K.; Velthof, G. Nitrogen Surplus—A Unified Indicator for Water Pollution in Europe? Water 2020, 12, 1197. https://www.mdpi.com/2073-4441/12/4/1197
Nitrogen and pesticide cycles in the agri-hydrogeochemical system
We start this section by defining the agri-hydrogeochemical system and looking at the pathways that nitrates and pesticides follow from the agricultural system to the drinking water supplies. We consider the challenges in monitoring and regulation, particularly of pesticides, and how contaminated water is treated in water works.
»Nitrogen and pesticide cycles in the agri-hydrogeochemical system
Data and indicators to regulate and monitor the use of nitrates and pesticides
We then look at what data and statistics there are available on the regulation, marketing and use of nitrogen and pesticides, what indicators are used to monitor them and how indicators are intended intended to support central and local administration and policy-makers, water companies in analysing the situation of diffuse pollution and selecting measures to protect drinking water resources.
»Data and indicators to regulate and monitor the use of nitrates and pesticides
Developing FAIRWAY agri-drinking water quality indicators (ADWIs)
The DPSIR model is defined as “causal framework for the description of interactions between society and the environment”. It was adopted by the European Environment Agency (EEA 2018). According to its terminology, social and economic developments (Driving forces, D), exert Pressures (P) on the environment and, as a consequence, the State (S) of the environment changes. This leads to Impacts (I) on ecosystems, human health and society, which may elicit a societal Response (R) that feeds back on Driving forces, on State or on Impacts via various mitigations, adaptations or curative actions (Smeets and Weterings, 1999; Gabrielsen and Bosch, 2003). In FAIRWAY we consider ADWIs within the DPSIR-framework. The adjusted DPSLIR-framework contains a new element, the Link Indicator.
»Developing FAIRWAY agri-drinking water quality indicators (ADWIs)
Agri-drinking water quality indicators at farm and drinking water levels
Agri-environmental indicators (AEI), as developed by OECD and Eurostat, are implemented and further developed for the monitoring and evaluation of the negative and positive impacts of agricultural activities on the environment. AEIs are used on European/national level (28 AEI are listed in fact sheets related to COM final 0508/2006 (Eurostat, 2018). The AEI are applied e. g. to evaluate/benchmark the transcript of EU-legislation at Member State level), at regional level (to monitor the impact of agriculture on environment, identify hotspots or focus subjects and areas for the agricultural advisory service) and at farm level (as decision aid tool for the farmer). Agri-drinking water quality indicators (ADWIs) to be developed in FAIRWAY are defined as indicators for the quality of drinking water. As drinking water may be produced from groundwater or surface water, ADWIs aim at the quality of both. As done for the 28 harmonised AEI (COM 2006, Eurostat 2018), we classified all ADWIs, which the case studies reported into the adjusted DPSLIR framework. We added further ADWIs according to a literature review. The ADWIs listed in the table may work as indicators by themselves or they are elements of compound indicators. Indicators for both, nitrates and pesticides, are listed in the same table, in order to avoid redundance as far as possible.
»Agri-drinking water quality indicators at farm and drinking water levels
Prioritisation of agri-drinking water quality indicators
All the ADWIs that are the subject of the survey among the case studies, those proposed by the case study leaders to be included in a further evaluation and those which, according to a literature review, are used for pesticide and nitrate monitoring/risk assessment are listed and described. Indicators which act in the agricultural sector as Driving forces and as Pressure indicators, are far more numerous than State respectively Impact indicators. The large number of agricultural Driving forces and Pressure ADWIs also explains, that from this part of the DPSLIR-model, many factors may influence water pollution. State indicators which are used for the evaluation of the water quality are on the contrary far more standardised, like the water quality standards they are supposed to monitor. A prioritisation of ADWI is therefore above all necessary for the Driving forces and Pressure indicators in the agricultural sector, in order to focus on the most significant, prevalent, effective and easy to use indicators. The survey on ADWIs already used in case studies and the most promising indicators leads to a first weighting of indicators.
»Prioritisation of agri-drinking water quality indicators
Further prioritisation and evaluation of agri-drinking water quality indicators
In order to further drive forward the proiritisation of the selected ADWIs in FAIRWAY, we intend to connect ADWIs from the agricultural and the water work side, using statistical methods. We also intend to further investigate on the Link indicator, especially how this ADWI fits in between the other indicators. We intend to examine
- the feasibility of indicators calculation,
- the link between indicators, and
- the relevance of some indicators, as statistical calculations give the mathematical expression for the link that exists between them.
For this purpose, a database of ADWI-data on catchments-level will be established by collecting data from the FAIRWAY-case studies. Preparatory work has been carried out, using the Voulzie case study, in order to specify the data request to the case studies. Statistical analyses of data of the Voulzie case study showed, that the spring discharge time series can be rather well explained by the evolution of the recharge of the year before. The first attempt to build this database enabled the calculations of indicators as well as the first links between Pressure indicators and State indicators. Finding the proper, statistically based link between agricultural Driving forces and Pressure indicators and the State/impact indicators might supply ADWIs on a reliable basis.
»Further prioritisation and evaluation of agri-drinking water quality indicators
IT/sensor and automatic sampler techniques for pesticide and nitrate sampling
Monitoring has evolved considerably over the past ten years and even more in recent years. There are broad avenues for innovation and, as part of the FAIRWAY project, a review of in situ monitoring methods has been achieved, in accordance with the chapter on participatory monitoring. Many methods can also be applied in the laboratory. A review showed that many tools (some are prototypes) and methods are being developed to improve measures for both nitrates and pesticides. The developed methods are based e. g. on optical sensors and paper based sensors. These tools make it possible to improve the confidence in the measurement while improving the analytic capacities of the devices (limits of measurements and types of molecules). In addition, relays with smartphones can be developed to facilitate the reading of the results and to trust them.
»IT/sensor and automatic sampler techniques for pesticide and nitrate sampling
Participatory monitoring: involvement of citizens
Participatory monitoring, although old in its concept, has become much more developed during the last decades. Several types of participative monitoring systems can be characterised in relation to the intended goal of the promotor. Participatory monitoring initiatives can often be considered successful as they allow measurement of phenomena at frequencies and locations that are not reachable by a team of researchers alone. On the other hand, associated difficulties have been identified. First, it is not always easy to find the right number of participants to complete a large program, some "site-specific" programs may be canceled due to lack of participants. Moreover, in our field of water and environment, participatory programs can only hope to change behaviors if educational tasks have been planned in the projects. Lastly, participatory monitoring programs generally only work with a coherent method to analyse the data (computer infrastructure and/or scientific manpower) that must be anticipated. If the educational tasks and IT tasks are taken into account, participatory monitoring programs are not necessary less expensive than the institutional programs. The review of in situ monitoring tools in development (even prototypical) suggests possibilities of access to increasingly simple and robust tools or new probes attached to smartphones. Thanks to these tools, some problems, such as the lack of participants and some analysis bias, could be resolved.
»Participative monitoring: involvement of citizens
From a survey among the FAIRWAY case studies on indicator use and from the the information in this section of FAIRWAYiS, the following aspects can be deduced:
- Regarding the two kinds of pollutants – nitrates and pesticides – the framing conditions are quite different:
- Nitrate is one single substance, being mobilised and immobilised, leached, transported by runoff and emitted. It is essential for plant growth and omnipresent, even under “natural” conditions.
- In contrast, around 250 so called “active substances” of pesticides are authorised by EFSA. Placement on the market of pesticide product needs national approvement. They may only consist of the registered active substances registered on EU-level, pure or in mixture, and of additives, for a better handling of the pesticide. Pesticides are supposed to be – to the greatest possible extent - harmless. They are supposed to degrade or at least to be absorbed by the soil matrix, but not to leach into groundwaters. Improper handling may however lead to runoff or drift and therefore to pollution of surface waters.
- ADWI are useful on all levels: at farm level as an aid in farmer’s consultation, at local or even national level as an evaluation and monitoring tool for administration work and for policy-makers. However, as more aggregated data show less standard deviation than the single datasets, correlation of ADWI with water quality could be stronger between data on a regional level than on farm level.
- ADWIs which act in the agricultural sector as Driving forces and as Pressure indicators are far more numerous than State or Impact indicators; this indicates how many factors from the agricultural side may influence water pollution. State indicators which are used for the evaluation of the water quality are – on the contrary – far more standardised, like the water quality standards they are supposed to monitor.
- Aim, size and structure of the different case studies are different, and so are the ADWIs in use. very few ADWIs are uniformly used throughout Europe.
- Common indicators on nitrate risk in use are rather simple statistics on fertiliser use, animal density or yield, but also N-budgets are applied.
- Pesticide risk indicators in use are compound/composite indicators, like the Treatment Frequency Index and Pesticide Load Index.
- Concerning pesticides, the DPSLIR-model can only be used, if data on the Driving force and Pressure side on the use of specific pesticides are available and can be linked to the State/Impact side. Since a regional differentiated data compilation of application data and a consequential estimation of the pesticide inputs is missing, pesticides found in drinking water can only sporadically be related to application data (SRU, 2016).
- Correlation analysis with data of the testsite showed, that the compound/composite indicators (field budget or Cassis-N surplus) were not the ones with the best correlation: budgets calculate N-losses from the root zone, and therefore do not take into account the N-losses in the unsaturated zone beneath the root zone (this is the reason why we introduce the Link indicator for the DPSLIR-framework). Composite indicators may show a low relative sensitivity for changing conditions (Buczko and Kuchenbuch, 2010).
- Calibration and validation of ADWIs against field data is of high importance (Buczko and Kuchenbuch, 2010a).
- The data acquisition scale may be a problem, because readily available data categories at the national level are difficult to access at the local level. Due to uncertainties related to the new regulation on data protection (EU 2016/679), but also due to a tightening of fertiliser legislation in some member states, questions on confidentiality of farm data arise in conjunction with the survey.