The causes of the environmental catastrophe in the Oder River in the summer of 2022 remained unknown for several weeks after it broke out. Environmental services intensively sampled the water, looking for toxic substances that could have caused fish mortality on such a massive scale. There were several hypotheses, rather unsuccessful, and laboratory tests confirmed none of them. Only the results of automatic measurements of chlorophyll a, pH and oxygenation, from a station located in Frankfurt, on the German side of the Oder River, provided indications pointing to an algal bloom, rather than toxic wastewater poisoning, as the cause of the massive fish deaths.
The sharp increase in the value of the first parameter and the diurnal fluctuations of the other two confirmed intensive photosynthesis during the day and respiration at night, or, in other words, a bloom, which became the charge of the golden alga hypothesis. To come to this conclusion, it was necessary to have the results of tests performed at the appropriate frequency. And here the stations for automatic measurement of water parameters proved to be a very good tool.
Water is not air
Voices were quickly raised that the current method of water testing, carried out within the framework of state environmental monitoring by traditional methods, does not meet the needs for early warning, including about threats of discharge of hazardous substances or phenomena of an ecological incident nature (such as the invasive haptophyte bloom in question). It would be different if we had automatic stations, like Germany.
Here comparisons were made to air quality monitoring, which the public had become familiar with a few years earlier during a period of heightened awareness of the smog threat. Since a system showing air quality on maps in virtually real time on a global, European Union or, finally, Polish scale can be accessed at the click of a button from a smartphone app, why not do the same for water? Most likely because water and air quality monitoring are governed by different laws and have different goals.
The thing is that water quality monitoring and air quality monitoring are completely different systems. This is due to both the differences between the atmosphere and hydrosphere, as well as different legal philosophies One can judge it differently, but the EU air and water monitoring systems view human health issues differently. In the case of the air, this is the primary goal. Here environmental and sanitary inspection play on the same team. In water monitoring, on the other hand, the primary goal is to assess ecosystem health, while public health goals are a distant prospect, based on the assumption that human health is a consequence of ecosystem health. The immediate health risks associated with water are the responsibility of the health inspectorate, not the environmental inspectorate, which in turn is concerned with ecosystem health.
Ecological status is not only water quality
Therefore, EU water quality monitoring in the sanitary field is governed by one set of rules, and in the environmental field by others. In the sense of the Water Framework Directive, it is geared toward assessing the overall condition of aquatic ecosystems, understood on the one hand as the presence or absence of toxic chemical pollutants (referred to by the chemical state of the waters), but primarily as the degree of deviation from natural conditions (referred to by the ecological state). Defined in this way, the state is a relatively stable phenomenon, possibly subject to long-term trends, and short-term changes in it may be within natural variability. They are treated as a deviation from the default equilibrium (we write about whether such a thing exists in nature at all in another article today) and should not condition the overall assessment.
Therefore, in WFD-compliant water status monitoring, physicochemical parameters and toxic pollutants, as a rule, are classified as averaged over an entire year or season. And not each measurement individually! And it is worth emphasizing that the legally binding evaluation criteria are precisely about seasonal averages, which means that applying them to individual measurements is unjustified and can lead to erroneous conclusions.
From a legal point of view, another very important issue arises – laboratory reliability. If a measurement of the state of the environment can have legal consequences, it cannot be made in any arbitrary way. Just as evidence of a temperature record will not be a reading from a private window thermometer, but only from a professional meteorological station, a bad physical or chemical water parameter must be established by a laboratory that is accredited and performs tests using a method that conforms to a specific ISO or PN/EN standard. Such procedures, as a rule, require the signature of a laboratory technician confirming that all standards have been met and that conditions at the laboratory or field station have been taken into account. An automated station will not provide such a signature. So it may signal a disturbing change in an environmental parameter, but it will certainly not meet the requirements of state monitoring.
Dozens of indicators are not five
Within the framework of ecological status, the WFD provides for monitoring of five biological elements, a dozen physicochemical water parameters and hydromorphological status, and within the framework of chemical status, about 50 priority substances. The vast majority of these parameters (except for hydromorphology and a few water quality indicators) – with the current state of technology – cannot be studied directly in the field. Admittedly, techniques such as environmental DNA studies are being developed, but they have a perspective more in biodiversity science. Their application to assessing the condition of biological elements in terms of the WFD is very limited. Priority substances, on the other hand, are generally chemically complex and require sophisticated chromatographs to detect and measure them. And these cannot be installed on a field probe.
Routinely used in aquatic ecology, multi-parameter probes test salinity (usually expressed as electrolytic conductivity), pH, temperature and oxygenation, possibly chlorophyll a. More advanced ones can measure nitrogen or phosphorus. So even if one wanted to use such probes to study the state of the water, it would be impossible to avoid taking water monthly for laboratory analysis of a whole range of other parameters.
It should also be borne in mind that many pollutants, including almost all toxic ones, can go undetected by such a system. Yes, a sudden discharge of saline water, such as from a mine or chemical plant, will be noticed. Similarly, sudden strong acidification or alkalinization. However, pesticides and many other toxic substances are generally organic compounds that are relatively poorly soluble in water and thus have little effect on its conductivity. The natural variability of salinity and pH can completely mask such pollution.
Could automatic monitoring have saved us from disaster?
This begs the question – since automatic stations are not suitable for monitoring water levels according to the requirements of the WFD, what are the German stations on the Oder River, cited at the beginning, doing? The answer is that they study the current state of the few water parameters that can provide information to emergency services about unexpected pollution and the need for more detailed studies. Similar stations are used by scientists or the National Park Service to study the state of the environment. In the language of science, this is even called monitoring, because the word has a large capacity for meaning. Suffice it to recall neighborhood monitoring or heart rate or blood pressure monitoring used in medicine. However, this is a completely different meaning than that defined in the WFD.
Imagine what would happen if we had automated water quality testing stations before July 2022. What would we have learned from them? For example, that the salinity of the Oder River is very high. Well, look at that! Except that we’ve known about this since at least the 1990s. In the 1970s. (As can be seen, for example, by looking into the report concluding the work of the Oder situation team). We would find that the pH and oxygen concentration show large diurnal fluctuations, and if the probe was equipped with a chlorophyll sensor – that this parameter has increased significantly. Which indicates a bloom; only that, not knowing why, the water is not green (which significantly reduced the credibility of the bloom hypothesis in the first weeks of its formulation).
What the probe wouldn’t tell me was the presence of an invasive algal species that needs a certain range of salinity for its survival. Unlucky for us, a species appeared that no automatic monitoring had any chance of either detecting or predicting. Yes, an automated station would have helped to interpret the phenomenon more quickly, but would it have protected us from it? Rather not.
And what will we do when some other super-aggressor (parasite? predator?) appears in our waters, which will depend on a completely different parameter? We will be at the starting point. Because many unpleasant surprises lurk in degraded, murky waters.
And what we seem to forget – monitoring alone does not predict anything, it measures the ongoing state. Of course, it should provide data for models and forecasts, only in order for us to forecast something in nature, we must first know its mechanisms. And with this we are not well. An aquatic ecosystem is not the weather, physics alone will not explain it. Well, and it is worth remembering that measurements, without a well-defined system of early warning and indication of the responsibility of environmental services in the situation of exceedances, will not be of much use to us either. The databases will swell, and we will be wise after the event again.
So why do we need automatic monitoring?
Member countries are obliged to carry out the provisions of the directives, not less. However, no one prohibits them from doing more, but these are other tasks. In this light, assuming unlimited budgetary resources, there is nothing to prevent the testing of certain water parameters on a continuous basis. However, this is not the task of state environmental monitoring. On the other hand, as much as possible it can be a tool for detecting sudden changes in salinity or oxygenation. Such information can be useful to services detecting water pollution. Whether it will be the provincial environmental protection inspectorate, the fire department or yet other services is a matter for consideration.
A system of automatic measurements of water parameters can be an important part of an emergency management system. It can also help in the search for sources of pollution. However, under the current system of EU law and with the current state of technology, it will certainly not replace traditional water quality monitoring. Perhaps in the future some elements can be used to supplement it. However, this requires prior testing and technical development.