Water, water everywhere, but is it fit to drink!?

2 Dec 2013

Prof Graham Mills of the University of Portsmouth gave us a fascinating lecture entitled, Water, water everywhere, but is it fit to drink!? on 14 Nov 2013 at Charterhouse School. The event was organised by the Thames and Kennet group with RSC Downland Section.

Professor Mills began by explaining there is only a fixed amount of water available on the planet; 97% of water is salty so is undrinkable and 2% is inaccessible, as it is locked away in ice caps. This leaves just 1% available for humans to use for drinking, agriculture, industry and personal needs. Any pollution that occurs to this 1% means that even less water is available for our use.

Water pollution comes in a variety of forms; chemical, biological, thermal, etc. When pollutants reach the aquatic environment, they can affect the environment in many ways. Those which are less dense than water can be volatilised into the atmosphere, those which have low water solubility go into the sediment and some are taken up by aquatic organisms.

It is the physical and chemical properties of the pollutant that determines where it will affect aquatic environment the most. Only some of the chemical pollutants (organic chemicals, inorganic chemicals and heavy metal) are regulated by legislation in Europe. The Water Framework Directive (WFD) came into force in December 2000. This legislation stated member states of the EU had to 'reach good chemical and ecological status' by 2015. This was done to enhance the status of and preserve aquatic ecosystems.

Originally, there were only 33 chemical substances that had to be monitored, but by 2013, 12 new compounds have been deemed hazardous to the environment so were included in the WFD. The WFD is driven by environmental quality standards, which dictate a maximum concentration and average concentration for individual pollutants.

Analysing a water sample involves collecting 1 - 10litres and carrying out a series of tests to identify each pollutant present. For organic pollutants, gas chromatography followed by mass spectrometry is used. If the body of water is used for drinking water, the concentration of pollutants is measured automatically every few minutes. Should the concentration go above the maximum concentration for a particular compound, an alarm system will activate and action is taken to prevent further dispensing of the drinking water into the public supply.

Biological methods can also be used to monitor pollutants in water: mussels and oysters can be deployed in cages. They both filter water through their gills everyday so the pollutants will bio accumulate in both molluscs.

An emerging threat of pollutants is pharmaceuticals and personal care products (PPCPs). These compounds present a serious threat to aquatic organisms by having a chronic effect due to a persistent low exposure in the water.

Currently there is no legislation for these products and their effects on the environment are unknown. In addition, with hundreds of drugs together in the water, they could produce new, more toxic compounds. Also drugs that are metabolised in the body produce metabolites. When these metabolites are excreted, they could have a more adverse effect than the parent drug on the environment.

James Nugent

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