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River pollution

A team from Cemagref in Lyon (FR) has identified a pertinent indicator of the level of pollution in rivers: the biofilm. A complex combination of bacteria, algae and fungi, the biofilm forms a viscous layer on immersed supports, such as the stones on a river bed. The biofilms are able to break down the pesticides that contaminate aquatic environments and modify their structure, diversity and functioning. Toxic substances, for example, can change the photosynthetic, respiratory or enzymatic activity of aquatic ecosystems, either definitively or temporarily. It is in this way that biofilms can serve as an early warning signal of pollution. It remains to characterize and distinguish the responses of biofilms to pollutants from those induced by environmental factors (current speed, physico-chemical composition, etc.). It is research of this kind that should help respond to the need set out in the Water Framework Directive to improve the ecological quality of European rivers.

I lost the flow of ideas after the sentence "Toxic substances, for example, can change the photosynthetic, respiratory or enzymatic activity of aquatic ecosystems, either definitively or temporarily".

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    That is a translation from French, I believe. "It remains to characterize" is not really English structure. They mean: The organization or Cemagref still have to characterize and distinguish [etc]
    – Lambie
    Jun 21, 2021 at 17:19

1 Answer 1

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Toxic substances, for example, can change the photosynthetic, respiratory or enzymatic activity of aquatic ecosystems, either definitively or temporarily.

The ecosystem can be altered by toxic substances. Photosynthetic, respiratory or enzymatic activity of the ecosystem are exmaples of what may be altered. The changes may be permanent or temporary. Changes to the ecosystem can have a noticeable (and therefore according to this hypothesis, measureable) effect on the biolfilm present in the ecosystem.

It remains to characterize and distinguish the responses of biofilms to pollutants from those induced by environmental factors (current speed, physico-chemical composition, etc.).

"It remains to" is not common except in the phrase "It remains to be seen". It means that something still needs to be done. In this case, characterizing the specific changes to the biofilm still needs to be done. Specifically, differentiating the changes caused by pollutants and changes caused by environmental factors needs to be done. Current speed and physico-chemical composition are examples of the environmental factors that may cause changes that need to be separated from changes caused by pollutants

It is research of this kind that should help respond to the need set out in the Water Framework Directive to improve the ecological quality of European rivers.

It has been decided that the ecological quality of European rivers must be improved and it is believed that working out how biolfilms react to pollutants(and distinguishing which changes are caused specifically by pollutants) could help with this.

Overall, it is saying that is has been noted that a biolfilm can be used as a measure or monitor of pollutants but more research into the biolfilm responses is needed for it to be a viable technique.

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  • Thank you very much for your answer. I was going to ask one more additional question. In this sentence "Toxic substances, for example, can change the photosynthetic, respiratory or enzymatic activity of aquatic ecosystems, either definitively or temporarily". With equatic ecosystems do they mean biofilm?
    – Oliver
    Jun 21, 2021 at 8:43
  • If this aqutic in-the-above-mentioned sentence is biofilm, what they are referring to with aquitic environments in the sentence "The biofilms are able to break down the pesticides that contaminate aquatic environments and modify their structure, diversity and functioning.
    – Oliver
    Jun 21, 2021 at 8:55
  • I think the aquatic ecosystems in both cases refers to the system as a whole. So the water, biofilm and any plants or animals that live in it altogether. I have edited my answer to be clearer about this Jun 21, 2021 at 15:38

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