Analysis of the monitoring data intercomparability for the Bulgarian – Romanian common stretch of the Danube River PP2 – National Administration Romanian Waters Carmen Hamchevici

Sub-activity 5.2 Water quality analysis for laboratory intercalibration Long-term Short-term Momentary TNMN data QA/QC analysis 2014 (9 months) Individual sampling June 2015 Common sampling (not bulk sample!)

(1) Long term data comparability 2 transboundary sections (ends of the common BG-RO Danubian stretch):  Pristol / Novo Selo (river km 854) and  Chiciu / Silistra (river km 375) 4 selected water quality parameters:  nutrients forms (N-ammonium, N-nitrates, P- orthophosphates, Total Phosphorous) Period of time: 1996 – 2011 Raw data from TNMN database (the TNMN data management center in the Slovak Hydrometeorological Institute, acknowledged)

Prior to data comparability: Analytical Quality Control (AQC) organisation of interlaboratory comparison in the Danube monitoring: agreed in 1992 based on a list containing reference and optional analytical methods Provider: (until 2012) the Institute for Water Pollution Control of VITUKI, Budapest, Hungary Name of the scheme: QUALCO DANUBE (4 distributions / year) Inventory of analytical methods used and performances (Technical Report)

Methods Entire datasets provided by BG and RO to ICPDR database Selected datasets based on the simultaneous sampling days during 1996 – 2011 Statistical approach STATISTICA 10.0 (StatSoft. Inc., 2005):  Basic statistic descriptives number of values, minimum, maximum, mean, median, confidence intervals for mean – 95%, lower and upper quartiles – percentiles of 25 and 75 respectively, percentiles of 10 and 90 respectively, range and standard deviation  t-test between two independent variables (BG and RO): powerful parametric test, but with strong limitations related to distribution and variance  Box-plots (graphical representation)

Entire datasets: number of annually results produced by BG and RO at Pristol / Novo Selo transboundary section for N-NH4 N-NO3, P-PO4 and Total P (1996 – 2012)

Basic descriptive statistics – Pristol / Novo Selo (all data) PARA M. COU NTR Y VALI D N MEA N CONF. - 95% CONF. + 95% MEDIANMIN.MAX.P25P75P10P90 RANG E STD.DE V. N-NH 4 BG1100,160,130,180,140,000,860,080,220,030,300,860,12 RO1730,230,200,260,190,021,320,120,300,050,451,300,17 N-NO 3 BG1111,481,361,601,390,374,611,071,900,772,214,240,64 RO1731,241,161,311,150,232,840,871,560,661,942,610,50 P-PO 4 BG950,0650,0570,0720,0600,0000,2500,0400,0800,0200,1100,2500,035 RO1730,0780,0720,0840,0700,0120,2700,0500,1000,0320,1300,2580,041 TP BG820,1470,1050,1900,1000,0401,6000,0820,1410,0680,2001,5600,194 RO1660,1170,0930,1400,0900,0181,9300,0700,1300,0530,1701,9120,151

T-test: the null hypothesis of H 0 : μ x = μ y (p=0.05) BG VS RO MEAN GROUP 1 MEAN GROUP 2 t- VALUE DFp VALID GROUP 1 VALID GROU P 2 F-RATIO VARIANCE S p VARIANCE S N-NH 4 0,160,23-3,792810, ,960, N-NO 3 1,481,243,572820, ,630, P-PO 4 0,0650,078-2, , ,3130, TP 0,1470,1171, , ,6480,007285

Box-plots (Pristol / Novo Selo – all data)

Basic descriptive statistics – Pristol / Novo Selo (simultaneous data) PARA M. CO UN TRY VALI D N MEA N CONF. - 95% CONF. + 95% MEDIA N MIN.MAX.P25P75P10P90 RAN GE STD.D EV. N-NH 4 BG RO N-NO 3 BG RO P-PO 4 BG RO TP BG RO

T-test: the null hypothesis of H 0 : μ x = μ y (p=0.05) BG VS RO MEAN GROUP 1 MEAN GROUP 2 t- VALUE DFp VALID GROUP 1 VALID GROUP 2 F-RATIO VARIANCE S p VARIANCE S N-NH N-NO P-PO TP

Box-plots (Pristol / Novo Selo – simultaneous)

Pristol / Novo Selo PARAM. COU NTRY VAL ID N MEANMEDIANMIN.MAX.P25P75P10P90RANGE STD.DEV. Water temp. RO BG SS RO BG DO RO BG pH RO BG Cond. RO BG (2) Short – term data comparability January – September

PARAM. COU NTRY VALI D N MEANMEDIANMIN.MAX.P25P75P10P90RANGESTD.DEV N-NH 4 RO BG N-NO 3 RO BG N-NO3 RO BG TOTAL N RO BG P-PO4 RO BG TOTAL P RO BG (2) Short – term data comparability January – September Pristol / Novo Selo

T-test: the null hypothesis of H 0 : μ x = μ y (p=0.05) BG VS RO (MIDDLE) MEAN GROUP 1 MEAN GROUP 2 t-VALUEDFp VALID GROUP 1 VALID GROUP 2 F-RATIO VARIANC ES p VARIAN CES w.temp SS DO pH Cond N-NH N-NO N-NO N Total P-PO P Total

Pristol / Novo Selo 2014 – Water temperature

Pristol / Novo Selo 2014 – Suspended Solids

(3) Momentary data comparability - June 2015 Chiciu / Silistra Pristol / Novoselo

First approach

Performance analysis Compliance checking: QA/QC Directive (2009/90/CE) criteria - EQSs set-out by the 2013/39/EC

Conclusions on data comparability Higher degree of comparability for simultaneous sampling days (same hydrological regime) Good comparability for short-term and momentary data (2014 and 2015) Differences: Need for bilateral discussion (sampling, preservation, storage and analysis) Technical performances to be analysed vs the QA/QC Directive Future steps : bilateral agreement in place and operational common sampling (bulk sample) intercomparison exercises with agreed frequency on-table discussions on obtained results

Contacts Thank you for your attention! Investing in your future! Romania-Bulgaria Cross Border Cooperation Programme is co-financed by the European Union through the European Regional Development Fund