Chemical contents of the water samples :
As for each sample, we used a compact laboratory which contains reagents and accessories for the determination of: pH, ammonium, nitrite, nitrate, calcium, oxygen.

Since all natural waterways contain bacteria and nutrients, almost any waste compounds introduced into such waterways will initiate biochemical reactions (which will be shown later). Those biochemical reactions create what is measured in the laboratory as the Biochemical Oxygen Demand (BOD).
The so-called 5-day BOD measures the amount of oxygen consumed by biochemical oxidation of waste contaminants in a 5-day period. The total amount of oxygen consumed when the biochemical reaction is allowed to proceed to completion is called the Ultimate BOD. The Ultimate BOD is too time consuming, so the 5-day BOD has almost universally been adopted as a measure of relative effect of pollution.
We measured the content of oxygen in each sample in the dark (to stop photosynthesis of micro algae) at 15°C for five days, the temperature of the water was 15°C with apressure of 1bar, if we changed the temperature or the pressure, the results would change too.

Biological indicators of the water samples :

After we returned to school, we looked at the benthic macroinvertebrates that the different waters contained and put their name in a determination key. To see plankton which is micro plants and micro invertebrates, we used a microscope. We had to count each species but not each animal to use biotic index, so his or her identification had to be precise.
A definition of bio-monitoring is to map the conditions of water by taking samples and analysing the organisms which are found, just like we have done in the other experiments.
Another part of bio-indication is bio-monitoring. In stead of looking at which organisms are living in the water, the temperature and the pressure at the time of the experiments are very important. Indeed the organisms belonging to a certain type of water change with these indicators. Our sample and our experiments have been made in October. For example, we wouldn't be able to see what kind of animals are in what type of water because it is winter and so it is too cold. Animals are dead. To get correct results, it is advisable to do several experiments.

 

Biological indicators of the French water samples :
Most benthic macroinvertebrates are insects throughout of the stages of their life cycles. Eggs become larvae, nymphs, adults, through gradual metamorphosis. We identified those animals thanks to a determination key.

In the water which came from the lake we found invertebrates : two species of caddisfly larvae,

In the water which came from the river next to the field, we found the same animals as in the water which came from the manure. We also found lots of unicellular algae like ciliata and euglenophyta:

In the Netherlands:
Our colleagues have taken a sample of water of :
=> Dead branch, not running water in which they found five Copepoda, one ciliata and three Euglenophyta
=> A canal in which they found two Peridinae (which are diatom), two Copepod, three species of Chlorococcales, one Rotifer, two Euglenophyta and two species of Diatom.
=> The river The Dommel in which they found five Peridinae, one Chlorococcale, two Euglenophyta and three species of Diatom.

 

Interprétation

Chemical contents of the French water samples :
Specialists estimate that water quality depends on mineral concentration. These factors are physical and chemical. As we took our samples in September, the temperature (about 15°C) and pressure were the same for all, so we will study only chemical factors :

Quality	Really good	Good		Middle	Bad	Really bad
Ammonium(mg/L)	From 0 to 0,1	From 0,1 to 0,5		From 0,5 to 2	From 2 to 8	8 and more
Nitrate(mg/L)	From 0 to 50				From 50 to 100	100 and more
Nitrite(mg/L)	From 0 to 0,1	From 0.1 to 0,3	From 0,3 to 1		From 1 to 2	2 and more
Oxygen(mg/L)	7	From 7 to 5	From 5 to 3		3 and less
BOD(mgO2/L)	From 0 to 3	From 3 to 5	From 5 to 10		From 10 to 25	25 and more

It is an important indicator since most aquatic plants and animals need oxygen in order to survive. The river system produces and consumes oxygen. At the same time, the river gains oxygen from the atmosphere through the aerating action of wind or turbulence (cascading water) and from plants through photosynthesis. Respiration from aquatic animals, decomposition, and various chemical reactions consume oxygen. The decomposition of organic matter discharged in wastewater consumes oxygen. If more oxygen is consumed than produced, dissolved oxygen levels decline and some sensitive animals may disappear.
Nitrogen is an atomic element, an essential part of amino acids and nucleic acids which are vital to all life. Plants convert ammonium or nitrate into this nitrogen oxides and amino acids to form proteins. The increase in available nutrients promotes plant growth, favouring certain species over others and forcing a change in species composition. The more there is dissolved nitrogen, the more available plants will grow quickly.
Most aquatic animals thrive in water whose pH is in the neutral range (6,5-8,5). Acid rain is the main contributor to aquatic pH changes.
The pollution infects and therefore contributes to the degradation of the environment. The quality of water is defined by its composition of dissolved salt minerals, and matters in suspension. As Micro-organisms depend on the pollution, their population may change with the quality of the water.

The animals we found correspond to this biotic index. Each animal corresponds to a quality because it has nutritive and oxygen needs.

Group I: organisms are sensible to eutrophication. They are selective carnivores and detritivores tubicoles. They die when the organisms concentration goes up because oxygen concentration goes down. Group II: organisms are indifferent to eutrophication, carnivores and necrophages are less selective, that is to say they eat what is available to them!

Group III is organisms who live in mud, they are detritivores and they show water that has too much organic matter.
Group IV contains little detritivore organisms who live for less than one year.
Group V contains only detritivores that eat mud.
The other animals found are only visible with a microscope, so they don't belong to the board of biotic index created to be used during a day out. Nevertheless, they have the same needs as the invertebrates visible to the naked eye.

As for the first sample: In water polluted by dead organic matters, there is an active decomposition time where bacteria multiply. They break down the organic matter with an enormous oxygen consumption. According to the amount of oxygen as available in the water, bacteria changes organic matters into mineral matters. Animals which can survive without much oxygen are animals corresponding to the fifth and sixth groups with a biotic index of 1-2. They are detritivores, smaller tolerant organisms, they cut dead organic matter as little as it will be dissolved, indispensable state to absorption by bacteria.
If all of the oxygen is consumed, it is the septic time where anaerobic bacteria, which can live without oxygen, will form reducing molecules. There is a large variety of bacteria in water polluted by fermentable organic matters. Some species degrade cellulose, starch, lipid or protein; some others use the decomposed products of these matters. These animals stop to respire but they can survive because they practice fermentation.

The other animals asphyxiate and die except insect larvae like mosquito larvae or some small worms as Tubifex or Limndrilus which proliferate, air breathing thanks to a long respiratory siphon. This corresponds to the seventh group with the biotic index 0. For the same reason, pulmonate snails can survive. Also, We can see in this water quality filamentous algae (Cladopora) and a lot of bacteria (Sphaerotilum)

As for the second sample: It comes from a pond, dead water area only renovated by rain. After two months of dryness, the water almost corresponded to the water which comes from the manure. Here we can see an organic pollution which will become a mineral pollution: this water is progressively overloaded by mineral salts. It results in a growth of nitrates which enables the phytoplankton and the aquatic plants proliferation. The chlorophyll concentration measure gives a good indication of eutrophication intensity (high biologic production). During this summer, the oxygen concentration decreases. The ecological condition will become similar to those in current water after organic pollution which will be layered by fermentation. The pond will evolve into the septic zone. The number of aquatic larvae, which only lives in clean water, will decrease; contrary to mosquito larvae.
A month later, after a week of rain, we returned to this pond. We had clean water thanks to the self-treatment which restores the water's good characteristics. We passed to a better biotic index, between seven and eight. When the organic nutritive matters become less concentrated, the density of bacteria population will decrease. The animals which need more oxygen will be able to increase. We can observe green alga as Spirogyra and some colony of phytoflagelle. With the increase of oxygen concentration, created by the photosynthesis and reventilation by rain, animals appear in the order of the grid in according to their sensitivity. When the self-treatment has ended, really good conditions are restored and we can see clean water fauna: stoneflies and caddisfly larvae which build a wall of twigs to protect itself, nonpulmonate snails, daphnia... The biotic index is really good, 7-10, with a majority of animals of the first and second groups.

Our third sample comes from a lake which is a semi-enclosed water renovated by a little river. Lakes are characterized by large still water surfaces. Their volume is considerable, compared to their slow flow. The consequence is that their renewal and their oxygenation are slow but enough if there is no pollution. The sample is characterized by a poor presence of minerals and by the presence of insect larva which correspond to fairly oxygenated water: dragonfly nymph, damselfly nymph are numerous. This water has a biotic index between five and eight.
With a geologic time scale, lakes will ineluctably disappear by packing, because of matters coming from the side basin and of the phenomenon linked with the increase in the number of plants and other organisms which live there.

Our fourth sample comes from a river near a field. We can observe the same animals as in the pond which came from the manure. Rain washed off fields: nitrate fertilizer flows in the river, that's a major source of water pollution. As a result of extensive cultivation of vegetables with chemical fertilizers, human beings have more than doubled the annual fixation into a biologically available form. This has occurred due to the detriment of aquatic habitats. The minerals, brought by the flow, feed the plants. In the same way, in this river, bacteria turn organic matters into minerals salt which make plants grow too much and so animals haven't enough oxygen during the night and die.

In the Netherlands

They used a different biotic index with four groups instead of seven groups. It is the quotient of Dresscher and Van Der Mark, that shows the measure of pollution with a formula :	3D+C-B-3A
	A+B+C+D

They have counted the number of species they found and they calculated the quotient of Dresscher and Van Der Mark. The grid just which follows shows their results:

Place	Number of species in indicator group				Result of the formula	Water quality
	A	B	C	D
Canal (NL)	0	2	4	1	0,714	Moderate polluted
Dead branch (NL)	1	2	0	0	- 1,67	Extremely polluted
River Dommel (NL)	1	2	5	1	0,33	Moderately polluted
Small river (FR)	0	2	4	0	0,33	Moderately polluted
Pond (FR)	0	0	2	0	1	Moderately polluted

So they show that the quality of water in the Netherlands is better than in France. Also the quality of running water is better than stagnant water.

So we can see that if humans don't add pollution to natural water, nature is able to clean itself alone. That's what the Dutch also said to us:
"Nature is able to clean the water. Nature does this with the help of micro-organisms. Micro-organisms can clear the waste of other organisms. Micro-organisms are for example bacteria, virus and other animals that consist of one cell. The micro-organisms use the waste as food. They break off the waste products to water and carbonic acid gas. These waste products are organic, for example rests of dead animals and plants."
So we can see that there is a natural cycle which permits to nature to stay clean enough and so allows animals and plants to live in.

Oxygen depletion and nutriment enrichment effects on organisms:

Overall increase in biomass but decrease in diversity: that is to say that tolerant organisms population increase but there is little diversity of species because organisms more sensitive decrease.

When chemical or organic concentrations change in natural conditions : =>the blue population accepts large changes but there are few species. =>the black population only lives in specific concentrations and so the population size is higher.

When chemical or organic concentrations change by adding of exogenous materials (that is to say materials which come from outside), generally, all the populations are affected in the same way: when the concentration of the pollutant is farther than the range of tolerance, the population size decreases brutally. The black one more sensitive and die with a smaller concentration.

In the Netherlands:
To keep the water clean in the Netherlands, the government has made a lot of statutes, for example the Statute Pollution Surface-water.
This Statute contains rules such as domestic effluent may not be drained off on soil ; domestic effluent may not be drained off to the surface-water ; enterprises have to have a Licence to drain of effluent-water in the surface-water.
The government also has organisations that check the quality of water. There are some independent organisations too. These organisations check the water by taking measurements.

There is also an international hall-mark, the Blue Flag. In the Netherlands, they use this hall-mark. The hall-mark is being handed over after the water has been approved, that means that the water is clean enough to swim in.
"For a decade people dumped their waste water in the nearest brook and nature itself took care of the rest. But when the number of habitants increased, the ground- and surface water got too much polluted. That affected the ability of water to clean itself.
That's why in the 20e century the government decided that they should give nature a hand. They developed a system which imitated the biological purification process.
The waste water that first leaves your house goes through the sewer to a water purification plant. There they pump it up, where after the water can be cleaned in three steps.
The first step is the mechanical purification. With a steal grate the 'big' pieces of trash are filtered out of the water first. Then the water goes to a sand catcher. The sand and fat that is caught from the water here is recycled for road-building. Meanwhile the water streams calmly to the pre-sedimentation tank, where the rest of the floating material is kept from the water. The silt from the base of the tank is carried down to the silt thickener. The waste silt gets burned. In some purification systems there is no pre-sedimentation tank and the water is immediately biologically cleaned.
The second step is the biological purification. The water is put into water basins which contain many bacteria just as in natural brooks. The bacteria break up waste products. Meantime, while that is getting taken care of the bacteria's get enough oxygen for instant blowing of air from the bottom of the basins or by using surface aerators. Because of the oxygen, the bacteria's keep moving and can't sink in, which is necessary in this stage of purification.
The last step is the after-sedimentation. The water streams slowly from the middle to the outside, over the edge of the after-sedimentation tank. The bacteria's are so heavy from eating the waste that they sink to the bottom. There they are caught and a big part of them goes back to the water basins. The cleaned water can go straight to a brook or a river.
They do use nature in their water purification plants. This is called biological purification. During biological purification micro-organisms, especially bacteria, clean water. They break off organic material, nitrates and phosphates.
There is aerobic and anaerobic biological purification. Aerobic purification means that the bacteria that clean the water need oxygen for the process. Anaerobic purification is without oxygen."
So we can see that in France and in the Netherlands, the stations of purification work approximately in the same way.

The measures taken by the state:
- The state takes all action to change agriculture methods into biological ones.
- To intensify the use of renewable sources of energy in transports and electricity production.
- To reduce the use of the motor vehicle.
- To encourage local councils to stamp organic wastes.
- The state takes measures for industries to treat their own used water.
- To avoid the use of chlorine even as a disinfectant for drinking water.
- To use detergent without phosphate.
- Doctors, surgeons and veterinary must reduce the use of antibiotics.
- The state finances research about the consequences of the exposition of pharmaceutical products in water reserves and pawns some preventive actions about the reliability of the results.
- To reduce urbanisation and create "green belt".
- The wastes of human's origin are not mixed with chemical wastes to be recycled.
- To build biological factories of treatment instead of chemical factories.
- The state should financially help the developing countries for the system of evacuation and treatment of used water.
- It should distribute educational programs about the consequences of the pollution of water and the building of stopping places to reduce it for the industries, farmers and citizens.

Bibliography:
http://www.epa.gov/: U.S. Environmental Agency for: Legislation, biotic index of water
http://zoology.muohio.edu/oris/ZOO462/notes/09_462.html for principles of pollution, ecology
http://en.wikipedia.org cyber encyclopaedia for minerals biological role
http://www.ac-rouen.fr/pedagogie/equipes/svt/biologie/iton/pres-iton.htm image of insects.
http://www.ulg.ac.be/cifen/inforef/expeda/eureau/cahier/partie3.html grid of biotic index

Dossier de Renard sur l'eau : clef de détermination de la microfaune et flore, stations d'épuration "Eléments d'écologie" written by François Ramade : écologie appliquée . "STOP" written by Laurent de Bartillat and Simon Retallack " Le petit people des ruisseaux" written by Marcel PIPONNIER " Biologie géologie", manuel de 2nd, collection Calamand

Annexe :
Excessive eutrophication examples :
Dystrophication will be the right word for excessive eutrophication! When eutrophication increases, we can notice changes of the organic composition because of the fermentation and the lack of oxygen : some anaerobic bacteria species live in the water without oxygen or in reducing silt and produce methane by hydrogen and carbon molecules deterioration with a simple structure. In areas poor in oxygen or without it, we can see some sulfobacteria, such as Desulfovibrio desulphuricans, which reduce sulphide sulphates and produce hydrogen sulphide.
Other anaerobic bacteria metabolize nitrogen compounds and emit ammoniac. Some bacteria species, which feed decomposed organic matters, which, proliferate in polluted waters, gather in a large colony, with a visible gelatinous and stringy shape. As for the Sphaerotibus natans: a heterotrophic bacterium common in waters polluted by carbohydrate organic matters, because it uses sugar as its main nutrition.
Beggiatoa alba is a sulfobacterium which lives in anaerobic silt in contact with water not completely devoid of oxygen by organic pollution: they need hydrogen sulphide and oxygen.
Numerous species of anaerobic sulfobacterium proliferate in water loaded with organic matters. Nevertheless, this kind of water also contains rich flora of fungi.
Contrary to the heterotrophic bacteria, the autotrophic bacteria help to carry oxygen to the waters.
When the oxygen levels increase at a suitable rate, we could see bacteria, which transform ammonia into nitrates.
The apodya lacteal brings mycelium colony that look like fleecy filament. This species needs a sufficient quantity of oxygen and organic nitrogen.
The fusarium aqueductum is a red fungi living in waters that are rich in organic matter.
A lot of others fungi species such as Mucor, Geotrichum, Penicillium... proliferate in waters and are infected by biochemical matters.
The metabolic needs of these organisms caused a huge drop of dissolved organic content.

In the active decomposition zone and in those nearby the downstream part, when the self-treatment start to show a result, ecological conditions are favourable to the proliferation of unicellular animals, because many of these species eat bacteria. In the deterioration zone, only very resistant microorganisms and a few flagellated can develop. But after this zone, Colpidium, Glaucoma, Penicilium, and sessile species (Carchesium, Epistylis) with a bacterium regime, proliferate.
Algae totally disappear from waters deoxygenated by an organic pollution. However, if the oxygen level stays sufficient, algae first decrease, and then grow. The proliferation of these autotrophic organisms results in the release of nitrates and phosphate by the bacteria, from organic matters present in the effluent.
The maximum density of alga phytocoenose is located near the beginning of the effluent emission. Species which proliferate there are adapted to rich in nutritive element areas: Oscillatoria, Phormidium (blue alga), Ulothrix (green alga), Euglena (phytoflagelle). In waters overloaded with nitrates, we can often observe a green alga Stigeoclonium.
Some Melosira and diatoms such as Gomphonema and Nitzschia paela meet each other in abundance, even in active decomposition zone, with sometimes species as Navicula and Surirella. The Cladophora Glomerata green alga often lives in rich in nutritive element areas. This specie proliferates when the degree of organic matters which turn into minerals is reached. It floats with a branched filament shape, larger than two metres.