Biodegradation Of Catchment Source Organic Matter In

Transcription

1 Biodegradation Of Catchment Source Organic Matter In Riverine Environments Merissa Marius 1, Adrian Collins 2, Anne Stringfellow 1, David Sear 3, David Smallman 1 1 Civil Engineering and the Environment, University of Southampton, UK, 2 ADAS, Wolverhampton, UK, 3 Geography and Environment, University of Southampton, UK

2 Presentation Outline Background Research Motivation Experimental Overview Results and Discussion Conclusions

3 Background Chalk river catchments are sensitive ecological systems, most with scientific designations within the UK. The ability to be able to easily identify influxes of organic matter can lead to a better understanding of river ecology. Fluorescence spectroscopy combined with PARAFAC have been highlighted as potential tools for measurement and identification of organic matter.

4 Research Motivation Work to-date looks predominantly at natural dissolve organic matter and pollution point sources, and correlating the source fluorescence to what is identifiable in the catchment. Dilution effects factored into detection Possible changes to the organic matter characteristic not considered Microbial degradation Transformation and quenching of detectable species

5 Experimental Overview River Itchen Chalk river system SSSI/SCA designation Wildlife directly impacted by river quality

6 Organic Sources Natural In stream Flora (IS) Bank Flora (BF) Watercress (WC) Anthropogenic Fish Food (FF) Farm Yard (FY) Road Verge (RV)

7 Set-Up & Analyses Solid Source Humic Substance extracted Fluorescence Organic Source + River water Aerated at 1 C for 55 days Supernatant Sampled at regular intervals Dissolved organic carbon (DOC) Fluorescence

8 Fluorescence Results Rayleigh Tyndall Effect C, A Humic-like T Tryptophan-like B- Tyrosine-like Chl Chlorophyll -like Chl C B T T A Rayleigh Tyndall Effect 3D EEM showing main fluorophores

9 Humic Substance Extracts EEMs In Stream Farm Yard Road Verge

10 Humic Substance Extracts EEMs In Stream Farm Yard Road Verge

11 Humic Substance Extracts Peaks

12 Biodegradation Eluent Peaks All peaks show initial intensity increase Effect of leaching

13 Biodegradation Eluent Peaks All peaks show initial intensity increase» 3 data trends 1) Steady degradation >leaching

14 Biodegradation Eluent Peaks All peaks show initial intensity increase» 3 data trends 1) Steady 2) Intensity plateau degradation =leaching

15 Biodegradation Eluent Peaks All peaks show initial intensity increase» 3 data trends 1) Steady 2) Intensity plateau 3) Continued degradation <leaching

16 Biodegradation Eluent DOC

17 DOC-HS peak correlation DOC: peak A DOC: peak C In Stream Bank Flora Watercress Road Verge Fish Food Farm Yard

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21 PARAFAC analysis Pre-processing and correction of raw data. 2 data array structures created Degradation EEMs for each organic source (8 spectra) Collated degradation EEMs (48 spectra) 2-3 components validated for array structures

22 PARAFAC results 7 Component 1 Component 2 Component

23 PARAFAC analysis Component 1 Component 2 Component 3 Peak C Peak A Peak T

24 PARAFAC analysis Component 1 Component 2 Component 3 Peak C Peak A Peak T IS IS BF BF BF RV RV - WC - WC FF FF FF - FY FY

25 Conclusions Fluorophores within an organic matter signature degrade disproportionally making correlations back to initial signature difficult. Leaching and degradation are competing processes which hinder the use of peak ratios and other correlation parameters to source discrimination and apportionment. PARAFAC cannot be used as stand-alone method to enable source discrimination via components.

26 Future work Building on the available data (number and source types). Identify and isolate active biogeochemical processes which result in observed changes in EEMs. Explore other statistical tests which can aid discrimination and apportionment of river source organics.