One of our ecological footprints… By Sarah Bennett

Landfills provide a way of hiding away the rubbish we create – out of sight out of mind.  However, research now shows that chemicals leaching from these landfills are polluting our rivers.  The work led by BGS scientist, Daren Gooddy, found that approximately 27.5 tonnes of ammonium a year finds its way from unlined landfills on the outskirts of Oxford, through a flood plain and into the River Thames. Here Sarah Bennett, a Stable Isotope Research Geochemist at BGS and co-author of the research, explains more...
Once ammonium enters the rivers, it breaks down to nitrogen.  The extra nitrogen can trigger excessive plant growth and decay, damaging water quality and starving fish and other aquatic organisms of the oxygen they need to survive.  Scientists are most worried about so-called blue-green algal blooms, which can produce toxins capable of killing wild animals, livestock and domestic pets.  In people, they can cause skin rashes, nausea, stomach pains, headache and fever.
Sampling groundwater on a floodplain in the winter is not always
      straight forward and requires both innovation and improvisation    
The source of the ammonium was identified with isotopes, a chemical fingerprinting technique, and this enabled the team to attribute the ammonium to household waste.  This isn’t the first time isotopes have been used to identify human impacts on the planet.  Back in August, Jonathan Dean discussed how isotopes provide evidence of human activities 2000 years ago during mining and smelting and more recently during the industrial revolution.  His work suggests that we are in a new geological age, the Anthropocene: where humans impact and change the environment (read Jonathan's blog here).

Aerial view of Port Meadow, Oxford, during flooding
As a society we are concerned with our current and future activities on this planet, but we also need to deal with the ramifications of our past mistakes.  These landfills are one such example; we’ve learnt to line our landfills with thick clay to prevent chemical leaching, but we still need to deal with the unlined landfills that represent thousands of historic landfills across the UK.  We’ll be drawing up new management plans for floodplains on the margins of towns and cities as a result of this work. 

You can read more about this research in the journal Science of the Total Environment.