Analysing fluorescent natural organic matter in groundwater

Posted 27 June 2011

The landscape of the Alta Cadena, one of the karst aquifers studied, showing the various potential sources of dissolved organic matter.

Measuring the fluorescence of organic matter dissolved in groundwater can provide new insight into how surface water infiltrates into aquifers, and the quality of the groundwater.

Matías Mudarra and B. Andreo of Universidad de Málaga, along with CWI core team member Andy Baker, have recently published results of one of the largest ever studies of natural organic matter fluorescence in groundwater springs.

The work involved analysis of fluorescent organic matter in nineteen springs in three karst aquifer in southern Spain was combined with inorganic water chemistry analyses to understand the infiltration processes and hydrogeological functioning of the aquifers.

Additionally, the research showed that fluorescence analysis would be useful in the assessment of contaminant vulnerability.

As surface water travels into groundwater systems, it will typically infiltrate through the soil. Water-soluble organic matter present in the soil can be transported into the groundwater by this this infiltration process.

It has long been known that much of this dissolved natural organic matter is fluorescent. That is, if it is illuminated with a high energy light source, some of this energy will be absorbed and then re-emitted at a lower energy as fluorescence.

In the case of natural organic matter, the absorption and fluorescence all occurs in the ultra-violet light spectrum, so we can't see it. But routine lab instruments can measure this fluorescence, detecting very low concentrations of organic matter with just very small volumes of water needed.

Dissolved organic matter in all aquatic systems, including groundwater, is not stable and can be degraded. Microbial degradation is particularly important, as the dissolved organic matter provides the energy needed for microbial communities.

In groundwater springs, the measurement of the amount and character of dissolved organic matter using fluorescence can provide unique information about the hydrogeological functioning of the aquifer.

The paper 'Characterisation of dissolved organic matter in karst spring waters using intrinsic fluorescence: relationship with infiltration processes' by Mudarra, Andreo and Baker, is published in the journal Science of the Total Environment at doi:10.1016/j.scitotenv.2011.05.026. Personal copies are available on request from Andy Baker.

The paper was written while Matías Mudarra was a visiting researcher at CWI in 2010.

Latest news

Floating though the dolines

Floating though the dolines

24 July 2020

Are you a fan of ABC's Conversations with Richard Fidler? Well, you might want to take a listen to this episode of the program with subterranean ecologist Stefan Eberhard.  

Read more…

New questions over Shenhua water modelling

New questions over Shenhua water modelling

24 July 2020

Take a listen to ABC Radio National Breakfast's segment on the controversial $1.5 billion Shenhua thermal coal mine on the New South Wales Liverpool Plains. Research undertaken by UNSW's leading groundwater expert Professor Ian Acworth indicates that the company's water modelling is flawed.

Read more…

Ban on toxic mercury looms in sugar cane farming, but Australia still has a way to go

Ban on toxic mercury looms in sugar cane farming, but Australia still has a way to go

18 July 2020

CWI's Professors Cameron Holley and Darren Sinclair and Australian National University's Professor Simon Haberle and Larissa Schneider recently contributed to The Conversation, discussing federal authorities announcement of "an upcoming ban on mercury-containing pesticide in Australia", highlighting Australia is "one of the last countries in the world to do so, despite overwhelming evidence over more than 60 years that mercury use as fungicide in agriculture is dangerous." 

Read more…

Ancient water to drain from farmland without ongoing joint management

Ancient water to drain from farmland without ongoing joint management

1 July 2020

The management of withdrawals of ground water in the Central West remains an area of hotly-contested debate. Associate Professor of Hydrogeology Bryce Kelly has spent over a decade studying groundwater in the Central West, and has credited groundwater with “saving rural communities from collapse”, but its potential for future drought-proofing depends on how successfully it’s managed. He says current withdrawals “will only be sustainable if the Narromine region gets flooded frequently enough to balance the volume of groundwater extracted."

Read more…

GWI Global Water Matters Podcast

21 June 2020

The UNSW-GWI Global Water Matters Podcast was launched in 2020 to share interesting and important water-related developments and insights from global experts across the broad spectrum of water-related disciplines. Born from the demand to continue the Water Issues Commentary seminar series under the constraints of social distancing, new episodes are released monthly.

Read more…