COUPLED MACRONUTRIENTS CYCLES IN HEADWATER STREAMS Impacts of DOM - - PowerPoint PPT Presentation

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COUPLED MACRONUTRIENTS CYCLES IN HEADWATER STREAMS Impacts of DOM nature and nutrients availability on DOM reactivity 28 / 10/ 2014 FOVET O., EVANS C.D., JONES D.L., JONES T.G., COOPER D.M. Scientific Interests Background 2004-2007 MSc

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COUPLED MACRONUTRIENTS CYCLES IN HEADWATER STREAMS

Impacts of DOM nature and nutrients availability on DOM reactivity

FOVET O., EVANS C.D., JONES D.L., JONES T.G., COOPER D.M.

28 / 10/ 2014

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FOVET O. / COUPLED MACRONUTRIENTS CYCLES IN HEADWATERS

28 / 10 / 2014

Background 2004-2007 MSc Agricultural Sciences – Montpellier SupAgro, Fr 2007-2010 PhD on Water quality in Open-channels – Cemagref Montpellier, Fr Since 2011 Researcher - INRA UMR SAS – Rennes, Fr Landscape hydrology and solutes transfers using experimentation, observation and modelling approaches

Scientific Interests

Stoichiometry Looking for the dominant controls: Priming effects ? Threshold effects? Biology Physical and hydrological conditions

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FOVET O. / COUPLED MACRONUTRIENTS CYCLES IN HEADWATERS

28 / 10 / 2014

Overview: “Turf2Surf”: Multi-scale response of Water quality, biodiversity and Carbon sequestration to coupled Macronutrients cycling from source to sea

The project

Atmosphere-Land Land-Freshwater Freshwater Estuary Sources Sea

My contribution:

  • Laboratory experiments based on 3 headwater types with contrasted water chemical features:

Peats – Forests - Grasslands

  • Light-UV treatments x Nutrient additions treatments
  • Measuring the changes in pH, Alk, [DOC], [DTC], [N], Anions, Cations, and Absorbance
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FOVET O. / COUPLED MACRONUTRIENTS CYCLES IN HEADWATERS

28 / 10 / 2014

Contrasted dynamics depending on the water chemistry: DOM tends to be degraded in Peat stream while it is produced in Agricultural stream When adding nutrients to peat water, the system switches on DOM production Implications for the real stream? On-going modelling approach

Results

0.10 0.18 0.30 0.53 1.80 2.74 2.29 3.49 0.46 0.00 0.05 0.10 0.15 0.20 0.25 2 4 6 8 10 [P-PO4] mg/l [DIN] mg/l Peat Agri Forest

Apparent production (mg C/l/d) depending on nutrient concentrations

REACTIVITY OF DISSOLVED ORGANIC MATTER IN HEADWATER STREAMS Impacts of DOM composition and nutrients availability FOVET O. (1,2,3), EVANS C. D. (3) , JONES D.L. (4) , JONES T .G. (5) , COOPER D.M. (3) 1 INRA, UMR 1069, SAS, Rennes, France 2 AgroCampus-Ouest, UMR 1069, SAS, Rennes, France 3 Centre for Ecology and Hydrology, Bangor , UK (Hosting laboratory) 4 School of Environment Natural Resrouces and geography, Bangor University, Bangor, UK 5 School of Biological Sciences, Bangor Unviersity, Bangor, UK www.rennes.inra.fr contact: www.ceh.ac.uk/sites/bangor.html
  • phelie.fovet@rennes.inra.fr
Introduction: Need to link the C-N-P macronutrients cycles in headwaters
  • What is DOM: A wide range of compounds from land vegetation and soil biomass as well as aquatic biomass (phytoplankton,
bacteria,...)
  • Streams act as active pipes to export DOM from land to sea: 80% of the total C fluxes impacted (Tranvik et al., 2009) :
  • Various processes either chemical e.g.: Photo-oxidation of photosensitive organic compounds such as peat derived DOM (Moody et
al., 2013) or biological (e.g. respiration, photosynthesis) with strong interactions with inorganic nutrients (Ni, Pi) M&M: Laboratory experiments Hiraethyln :Grasslands, sheep grazing 7.4 km2 Water cool bath Controlled UV- Light exposition Nant y Brwyn Upper: Peats 1.1 km2 Glasgwm: Forested 7.2 km2 Results: (1) All DOM is not the same 8 10 12 14 16 18 20 10000 20000 30000 DOC mg/l Cumulative irradiance kJ/m2 Peat stream LIGHT DARK LIGHT+HgCl2 1 2 3 4 5 10000 20000 30000 DOC mg/l Cumulative irradiance kJ/m2 Forested stream LIGHT DARK LIGHT+HgCl2 2 4 6 8 10 10000 20000 30000 DOC mg/l Cumulative irradiance kJ/m2 Agricultural stream LIGHT DARK LIGHT+HgCl2 Peat : Photochemical oxidation: 26% decrease of [DOC] Biological Production of DOC:+1.6 mg/l Farmland: Production of DOC: 128% increase of [DOC] No photodegradation measurable Forest: Not clear (low levels of C and nutrients) General decrease of SUVA and aromaticity SUVA=0.052 [DIN]=0 mg/l SUVA=0.020 [DIN]=3 mg/l SUVA=0.023 [DIN]=0.3 mg/l Results: (2) Nutrient additions enhance the production of DOC in all waters Discussion and Perspectives 5 days recirculation = total irradiance equivalent to 1 sunny day 9 14 19 24 29 34 1 2 3 4 5 mg DOC/l Days Peat stream LIGHT DARK LIGHT+N DARK+N LIGHT+P LIGHT+N+P
  • Addition of nutrient enhances the DOC production
  • N and P appear co-limiting
  • Photo degradation of Peat derived DOM can be significant
  • Current understanding suggest that DOM is photo-degraded as CO2 or partially photo-oxidized (DOC ox) (Cory et al., 2014), but our
results suggest that photo oxidation process may enhance new aquatic DOC biological production via inorganic nutrient release.
  • Possible sources of carbon for this production are particulate organic carbon, and mineral carbon
  • On-going modelling approach for estimating reaction rate as a function of inorganic nutrient and comparison with modelled residence times
in the Conwy river and estuary. Sampling sites in Conwy catchment North Wale, UK Experimental set-up 2 6 10 14 18 22 1 2 3 4 5 mg DOC/l Days Agricultural stream DARK LIGHT LIGHT+P LIGHT+N+P DARK+N Wale s Englan d Liverpool Wales Acknowledgements This work benefited from the Agreenskills program me and takes part of the Turf2Surf project: “From Source to Sea”, funded by the NERC Macronutrient Cycle Programme Contact : ophelie.fovet@rennes.inra.fr References Cory et al., 2014. Sunlight controls water column processing of carbon in arctic freshwaters. Science 345, 925. Moody et al., 2013. The rate of loss of dissolved organic carbon (DOC) through a catchment. Journal of Hydrology, 492, 139–150. Tranvik et al., 2009. Lakes and reservoirs as regulators of carbon cycling and climate. Limnol. Oceanogr., 54(6, part 2), 2298–2314. 4 8 12 1 2 3 4 5 mg DOC/l Days Forest stream LIGHT LIGHT+N LIGHT+P LIGHT+N+P DARK DARK+N
  • 1
  • 0.8
  • 0.6
  • 0.4
  • 0.2
0.2 0.4 Relative variation of [N-NO3] PEAT AGRICULTURAL FOREST
  • 0.25
  • 0.2
  • 0.15
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  • 0.05
0.05 0.1 Relative variation of [P-PO4] PEAT AGRICULTURAL FOREST Biological consumption of P and N, Release due to photo-degradation?