Sampling frequency and uncertainty: Examples from Norwegian case studies

Transkript

1 Helcom workshop May 18, 2015 Sampling frequency and uncertainty: Examples from Norwegian case studies Eva Skarbøvik & Per Stålnacke Bioforsk Norwegian Institute for Agricultural and Environmental Research

2 Focus on: loads and concentrations of sediments and sediment associated pollutants

3 THE OVERALL PROBLEM DISCUSSED: how often do we need to measure to get an accurate and precise result? Or at least a result with acceptable uncertainty?

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5 Lets first look at concentrations The EU Water Framework Directive (WFD) operates with mean (and max) concentrations in rivers and creeks WFD does not include sediments, but includes sediment associated substances

6 Rivers (including creeks) - eutrophication Quality element Minimum Recommended Invertebrates Each 3rd yr Annually, 3 times/yr Nutrients Annually, 4 times/year Annually, each 14th day (+during high water discharges) (Fish) Each 3rd yr Once a year, annually (Temperature/ ice) Annually, 4 times/yr Continuously (Oxygen) Annually, 4 times/yr - (Turbidity) - - Benthic algae Each 3rd yr Each 2nd yr (once a year) (Macrophytes) Each 3rd yr Once a year each 2nd yr Norwegian WFD guidelines for operational (and surveillance) monitoring. 6

7 Sediment associated substances: Example from Numedalslågen, 5500 km 2 catchment area, Southern Norway, based on monthly data from : Substance SPM Arsenic (As) Lead (Pb) Nickel (Ni) Total phosphorus (TP) Orthophosphate-P (PO 4 -P) R 2

8 Glomma 100-yr flooding in 1995

9 River Glomma during the 1995-flood

10 Particle associated and dissolved substances can react quite differently Q TP Q TN River Glomma during the 1995-flood

11 WFD and mean concentrations: Mean concentrations defines status If biology shows good status then chemical parameters such as TP and TN must be checked. If the mean concentration of TP or TN is bad, poor or moderate, the water body becomes in MODERATE status. ECOLOGICAL STATUS HIGH GOOD MODERATE POOR BAD

12 Investigation in River Numedalslågen : Sediment data were collected twice-a-day Then we used these data to assess the representativity of less-frequent data. (both in terms of mean concentrations and loads) Station 1 Station 2 Skarbøvik et al. 2012, Sci Tot Env.

13 26/01/ /02/ /03/ /04/ /05/ /06/ /07/ /08/ /09/ /10/ /11/ /12/ /01/ /02/ /03/ /04/ /05/ /06/ /07/ /08/ /10/ /10/ /11/2002 SPM mg/l : 600 mg/l Daily sampling (NVE) Max mg/l Monthly sampling (from RID) Max 45 mg/l mg/l Skarbøvik et al. 2012, Sci Tot Env.

14 Another Catchment: Morsa and River Hobølelva Lake Sætertjern Lake Bindingsvn Lake Langen Lake Våg Lake Mjær River Kråkstadelva River Hobølelva #* River Veidal River Mørkelva River Svinna Western basin #* Lake Vansjø Eastern basin Lake Sæbyvn Meters

15 Total phosphorus average concentrations in River Hobølelva (south-eastern Norway) samples/yr Average TP Conc at different sampling frequencies Snittkonsentrasjoner av totalfosfor ved ulik prøvetakingsfrekvens Alle prøver All samples Forthnightly Monthly Hver 14 dag Hver måned Env goal mikrogram/liter Skarbøvik & Haaland 2010, Vann 45(2)

16 Average TP Conc at different sampling frequencies Snittkonsentrasjoner av totalfosfor ved ulik prøvetakingsfrekvens Alle prøver All samples Forthnightly Monthly Hver 14 dag Hver måned Env goal mikrogram/liter Skarbøvik & Haaland 2010, Vann 45(2)

17 Average TP Conc at different sampling frequencies Snittkonsentrasjoner av totalfosfor ved ulik prøvetakingsfrekvens Alle prøver All samples Forthnightly Monthly Hver 14 dag Hver måned Env goal mikrogram/liter Skarbøvik & Haaland 2010, Vann 45(2)

18 Average TP Conc at different sampling frequencies Snittkonsentrasjoner av totalfosfor ved ulik prøvetakingsfrekvens Alle prøver All samples Forthnightly Monthly Hver 14 dag Hver måned Env goal mikrogram/liter Skarbøvik & Haaland 2010, Vann 45(2)

19 Average TP Conc at different sampling frequencies Snittkonsentrasjoner av totalfosfor ved ulik prøvetakingsfrekvens Alle prøver All samples Forthnightly Monthly Hver 14 dag Hver måned Env goal mikrogram/liter Skarbøvik & Haaland 2010, Vann 45(2)

20 Average TP Conc at different sampling frequencies Snittkonsentrasjoner av totalfosfor ved ulik prøvetakingsfrekvens Alle prøver All samples Forthnightly Monthly Hver 14 dag Hver måned Env goal mikrogram/liter Skarbøvik & Haaland 2010, Vann 45(2)

21 0.6 Question to managers TP (mg/l) 0.5 When 0.8 would you like me 0.4 to take your 4 samples? TP i Hobølelva TP (mg/l) Env goal

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23 Monitoring 46 rivers for 20 years From north to south To assess loads to the sea Part of the Oslo-Paris (OSPAR) Convention to assess pollutant loads to the North Atlantic

24 Number of parameters Tot-P, Tot-N, NH4, NO3, PO4 SPM, TOC, SiO2, Cond, ph Cd, Cr, Cu, Ni, Pb, Zn, As, Hg Lindane, PCB Continuous Water Discharge Frequent monitoring => 4 12(15) samples/year

25 The purpose of the monitoring: Metals, nutrients, pesticides River Alta Cu Annual loads to the sea Trends?

26 Do we trust the data? Do we trust the trends? And does it matter?

27 Investigation in River Numedalslågen : Sediment data were collected twice-a-day Then we used these data to assess the representativity of less-frequent data. (both in terms of mean concentrations and loads) Station 1 Station 2 Skarbøvik et al. 2012, Sci Tot Env.

28 Loads calculated by different methods and sampling frequencies Skarbøvik et al. 2012, Sci Tot Env.

29 Skarbøvik et al. 2012, Sci Tot Env.

30 Winter episode (Øygarden, 2000) January 30 Runoff: 25 mm Soil loss: 2 kg ha - 1 January 31 Runoff: 77 mm Soil loss: kg ha -1

31 Short-term variability in nitrate-n concentrations on a small agricultural catchment (Høyjord /S Norway) October 6-9, 1995 (Vagstad, Deelstra and Eggestad)

32 Does it matter if we get it wrong? Death of sugar kelp in the sea Have sediments or nutrients increased over time?

33 Objectives Determine environmental state Estimate loads Assess effect of measures Assess trends Process understanding Source apportionment Sampling strategy Grab sampling Composite sampling (incl. passive samplers) Continuous sampling (incl. sensors) Station network Few stations Stable network Many stations Changing network Duration Long term Short term Parameters Many Few Stable Variable

34 To sum up The understanding of transport mechanisms of sediment associated substances in rivers seems to be under-communicated Uncertainties in mean concentrations (and max concentrations) are not taken into management consideration Huge monitoring programs sample too infrequent and therefore have high uncertainties

35 Future? Today, many monitoring programmes in Europe are being reviewed due to the WFD, MSFD. Important to ensure that future monitoring and data interpretation are done according to current knowledge. Important to bridge the gap between disciplines; and between science and management.

36 Thanks for listening!