Results from the RCN-project EUTROPIA EUTROPIA: Processes - PowerPoint PPT Presentation

Results from the RCN-project EUTROPIA EUTROPIA: Processes governing leaching of Phosphorus fractions to surface waters Phosphorus fractions to surface waters and effects of changing environment O. Røyseth et al. D. Barton G. Orderud E. Romstad M. Beckman et al. H. Gunnarsdottir T. Andersen, A. Engebretsen R. Vogt et al.

EUs Water Framework directive Requires a good surface water q g status and that the condition of all water reserves should not have large deviations from their natural f condition by the year 2015 Scientists are required to assess the original- and present state of the environment, and to predict future trends RCN project Eutropia, XV-IHSS

The problem Eutrophication is usually the main cause for not fulfilling the requirements for good ecological quality in agricultural districts g 45% of the anthropogenic P input to Norwegian surface water originates from agricultural areas P is mainly transported in the rivers adsorbed to clay particles P is mainly transported in the rivers adsorbed to clay particles (Particulate P) Natural background flux of P Mainly in the form of dissolved natural organic matter ( DNOM-P ) RCN project Eutropia, XV-IHSS Miljostatus.no

Study site – Western Vansjø A l k A lake with strong ith t eutrophication causing frequent blooms of frequent blooms of cyanobacteria Below marine limit Sand or bare igneous rock on the ridges on the ridges Marine clay sediments enriched in P in valley bottom RCN project Eutropia, XV-IHSS

Western Vansjø Western Vansjø Natural eutrophic lake system with anthropogenic loading p g g from agriculture Forest dominates Only 15 % Only 15 % agriculture RCN project Eutropia, XV-IHSS

The problem continues No clear effects of abatement actions 125 Million € is used on abatement measures in the case study watershed No apparent improvement Without the implemented measures the situation would likely been worse The processes that govern The processes that govern the P fluxes are influenced by several environmental pressures p RCN project Eutropia, XV-IHSS

Pressures - Changing environment Pressures Changing environment the last 30+ years Climate: Increase in amount and intensity of precipitation and a 2ºC increase in the average winter temperature in the Oslo region Increased surface runoff causes enhanced soil erosion and Increased winter temperature causes more frequent freeze thawing cycles leading to frequent freeze-thawing cycles leading to even more soil erosion and thereby greater influx of nutrients adsorbed to the soil RCN project Eutropia, XV-IHSS

Effect of precipitation on P in Vansjø Good inter annual co variation Good inter annual co-variation between precipitation amount and Tot-P T. Rohlack, NIVA RCN project Eutropia, XV-IHSS Thomas Rohrlack, NIVA

Drivers - Changing environment Drivers Changing environment the last 30+ years Climate: Climate: Increase in amount and intensity of precipitation and a 2ºC increase in the average winter temperature in the Oslo region Increased surface runoff causes soil erosion and Increased winter temperature causes more Increased winter temperature causes more frequent freeze-thawing cycles leading to more soil erosion and thereby greater influx of nutrients adsorbed to the soil Landuse: Urbanization , deforestation, draining of wetlands and removal of riverbank vegetation, as well as encroachments such as modification of meandering streams to straight canals and piping of open brooks. Changes in agriculture ; Tile drainage Changes in agriculture ; Tile drainage Reduced S deposition: SO 4 2- , which in acid lakes in southern Norway constitutes the dominant anion charges, has decreased by about 70% has decreased by about 70%. → This has led to a decrease in Al 3+ leaching and reduction in Ionic strength (I) → and thereby an increase leaching of DNOM → causing likely an increased natural flux of P-DNOM g y 3- in eutrophic lakes → Al 3+ is used to remove PO 4 → Reduced I gives more soil erosion Skjekvåle, 2007 → and thereby an increased transport of Particulate-P RCN project Eutropia, XV-IHSS

Promising new analysis method of P i i l i th d f bio-available nutrient compounds in water at NIVA Adenosine monophosphate CNP robot Diffuse Gradients Autoanalysator –N, P, C Auto in Thin Films (DGT) passively TotP, TotN, TOC/DOC, 3 channels Sampler accumulate TOP TOP P-compounds TON LIMS, Our experiments have shown that WEB TOC ( same as for TON?) these DGTs are also able to sample Low Molecular Weight (LMW) organic Autoanalysator næringsalter P-compounds in a N, P , Si 4 – 5 channels Auto non-destructive manner Sampler NH4 NO2 ( also sep As needle ) LIMS, WEB NO3 with Cd PO4 SiO2, ( also sep AS needle) RCN project Eutropia, XV-IHSS

Some preliminary results P fractionation P fractionation Large variation depending on discharge depending on discharge and land-use High conc. of Particulate P esp during Particulate P esp. during discharge Episodes (E) Particulate-P dominate in Particulate-P dominate in runoff from Agricultural land DNOM-P dominate in discharge from forested catchments RCN project Eutropia, XV-IHSS Data: BioForsk/Morsa

Lake What happens to the P fractions? to the P fractions? Total-P in the lake vary between 15 – 27 μ g P/L E 85% 85% Streams S E E E E E Lake Relatively little total P is found in the lake R l ti l littl t t l P i f d i th l k If so - then increases in the natural relative to what is found in the rivers flowing into the lake Is it possible that Particulate-P does not contribute significantly background concentrations of DNOM-P from background concentrations of DNOM P from to the total loading of P as this is bound to Al and just settles into the forest soils may be of great significance sediment? RCN project Eutropia, XV-IHSS

Winter lake water chemistry Due to ice-cover during the winter Grazing by alga is minimized minimized No photo-oxidation � Lake water reflects more the effect of river influx About 25% of the About 25% of the total P in the lake is DNOM-P Tot-P varies from 12 – 24ug/L RCN project Eutropia, XV-IHSS

Monitoring of a forested watershed Poorly buffered acid sensitive site Poorly buffered acid sensitive site Barren rock with pockets of sand k t f d 50 cm loam RCN project Eutropia, XV-IHSS Deep marine deposits with layers of clay

Results so far Soil water chemistry in forest Soil water chemistry in forest 5 μ M Al i 16 μ g tot-P RCN project Eutropia, XV-IHSS

Episode st dies Episode studies in a forested site Recent episode p studies in Dalen show that pH varies from 4,3 – 5,9 Conc. of DNOM has a negative response to increased runoff RCN project Eutropia, XV-IHSS

Significance of P leaching from forest P leaching from forest Rough estimate: 85% of the watershed is forest Avg. total-P from forests is 16 μ g P/L � The natural background flux from forests are found to contribute with approx. 20% - 25% of the total P loading to the lake 75% of total P from forested watersheds is organic P 75% of total P from forested watersheds is organic P There has been almost a Skul. 40 Oset doubling of the concentrations 35 Lang. of DNOM over the last 25 years 30 Alun. g Pt/l 25 25 � This represents an increased Colour, mg 20 total P loading of 7,5% 15 In the lake a significant fraction of the 10 5 organic P is likely bio-available and more organic P is likely bio available and more 0 may become available by photo-oxidization 1975 1980 1985 1990 1995 2000 2005 2010 RCN project Eutropia, XV-IHSS

Significance of Precipitation with Aluminium Precipitation with Aluminium Water containing 5 μ M of Al 3+ is running out of the forested watershed Aluminium is a strong co-precipitating agent for P Downstream the forest runoff containing Al 3+ mixes with alkaline and P rich runoff from agriculture Al(OH) Al(OH) 3 precipitates and co-precipitate PO 4 i it t d i it t PO 3 3- Rough estimate: 5 μ M Al/L extrapolated for the forested area of the whole watershed provides an potential for precipitation of 43 t P/yr provides an potential for precipitation of 43 t P/yr. Total flux of P to the lake is now approx. 39 t P/yr. During the acid rain period there was likely a 3 times greater Al leaching. This could potentially precipitate out more than 130 t P /yr. Al 3+ OH - PO 4 3- Al(OH) 3 Al(OH) 3 PO 4 RCN project Eutropia, XV-IHSS

Thank you for your attention y y RCN project Eutropia, XV-IHSS