Bathing and swimming in the natural water bodies are one of the most popular recreational activities in the world. For many people, going on holiday is equivalent to enjoying the sun, beach and sea. In many countries in evey corner it is possible to find a pond or lake to swim or take a bath or do some recreational activities. Certainly everyone looking for recreation near or in the water wants the water body to be free from health hazards. In some countries taking bath in rivers water and lakes is a relegious tradition and therefore the importance of the water quality arised alot.
The most probable problem can be caused by nutrient inputs, in particular phosphates and nitrogen compounds, which may lead to eutrophication and facilitate a massive growth of algae (algal blooms).
Cyanobacteria ("blue-green algae") in particular produce toxins and allergens. They can cause acute health problems (for example conjunctivitis, eczema) or even have chronic detrimental health effects (liver damage). Another source of pollution of bathing waters is the surface run-off after heavy rainfall. Swimming after heavy rainfall should therefore for some days be postponed until the natural purification process has set in.
Not all blue-green algae blooms and scums are toxic, but you can’t tell just by looking at them, so it is best to assume they might be and check the information provided by local authorities.
These cyanotoxins can kill wild animals, farm livestock and domestic pets. In humans, they can cause rashes after skin contact and illnesses if swallowed.
To keep risks to a minimum and ensure control, officially registered bathing waters in the European Union have been subject to regular monitoring during the bathing season since the 1970s.
In 2006 the EU Bathing Water Directive of 1975 was updated and replaced by a Directive that is in line with the latest scientific research. The revised directive entered into force on 24 March 2006. Since then the federal states have implemented the EU Bathing Water Directive in national law and issued conforming countries regulations. In Germany there are many bathing waters registered and monitored in accordance with the EU Bathing Water Directive. In 2016, 1925 inland waters and 367 coastal waters were registered as bathing waters. The states are responsible for the enforcement of the legal provisions, i. e. for the designation and monitoring of EU bathing waters. They publish information on bathing water quality on the Internet.
In the other hand the water turbidity is not necessarily a sign of poor bathing water quality. By the same token, clear water can still be contaminated with bacteria.
Open bathing waters along inland water courses and lakes and along coastal waters can be polluted with pathogens too. Sanitary problems are mainly caused by discharges from sewage treatment plants and combined sewers and from urban and agricultural run-off. They can lead to fever, diarrhoea and vomiting in those who come into contact with the contaminated water.
Regular Monitoring the Algae in the early stage is the only practical solution to protect human and pets against the bathing water common pollutions. Conventionally many authorities uses simple Sechi diskes for monitoring the water quality but this has been proved that is not enough and complementry tests is needed. The major problem which is a very good indicative of the bathing water quality is the cyanobacteria and micro algae concentration in the water. In case the concentration of the cyanobacteria increaed in any bathing water the authorities can plan in the early stage to protect the poeple and pets to swimm in that special waterbody. WHO regarding this has published a guidline which regulate the bathing water quality based on the total chlorophyll concentration in the water. Chlorophyll is like a proxy for detection and measuring of the phytoplankton or microalgae in the water.
|Level of risk||Health risks||Recommended actions|
|10 µg l-1 chlorophyll a with a dominance of cyanobacteria||Short-term adverse health outcomes (e.g. skin irritations and gastro-intestinal illness, probably at low frequency)||Post on-site risk advisory signs Inform relevant authorities|
|50 µg l-1 chlorophyll a with a dominance of cyanobacteria||Potential for long-term illness with some species Short-term adverse health outcomes (e.g. skin irritations and gastro-intestinal illness)||Watch for scums Restrict bathing and further investigate hazard Post on-site risk advisory signs Inform relevant authorities|
|Cyanobacterial scum formation in bathing areas||Potential for lethal acute poisoning Potential for long-term illness with some species Short-term adverse health outcomes (e.g. skin irritations and gastro-intestinal illness)||Immediate action to prevent contact with scums; possible prohibition of swimming and other water-contact activities Public health follow-up investigation Inform relevant authorities|
Besides the other conventional sampling methods which usually ends up with simple sechi disk and taking one or two sample and tranferring the sample to the laboratories, great thanks to the in-situ and submersible spectrofluorometric methods which enbables fine scale profiles vertically and horizontally too with no need to use any reagent or sample transferring to the lab. In the laboratory the authories might use different methods which all might bring different results. The fact is that the all analysis methods needs reagent and sample preperation and indeed a skilled person to run the analysis. This is a time consuming task and needs large investment too.
This is valuable, particularly for monitoring large water bodies and coastal areas for highly variable patterns of chlorophyll concentration (algal and/or cyanobacterial biomass). AlgaeTorch has been used successfully to monitor variability in phytoplankton biomass and species composition in the bathing water for a long time in the water.
In the other hand AglaeTorch can be design fully automated on the buoy systems which allows high frequency in-situ sampling with abiltiy to approach online real time data. The buoys has solar panels and which enables power supply in distinct area for the measurement.
In addition is important to mention that however the satellite images recently are able to detect the extent of the algae and surface accumalation but indeed all satelite images requires the land base measurement correlation. In the other hand referring to the biological behavoir of different algae classess it might happen often to see no algae accumlation in the surface. Therefore the measurment in the different depth of the bathing water has higher importance. Besides it should be mentioned herer that the remote sensing specially statelite images are not possible to detect during the cloudy weather.
The AlgaeTorch has inbuilt GPS. This is a super feature which give possibiltyto insert the recorded data in the google earth and provide a very good visualized reports as below picture:
Another application is the use of a flow-through system like AOA (AlgaeOnlineAnalyzer) deployed on ferries. Real-time data for chlorophyll a distribution and concentrations, and potentially for cyanobacterial and other harmful chlorophyll pigments in seawater can be generated this method. In europe the project named Ferrybox since years gathering wonderfull information about the different pathways in the european seas.