Analysis of the monitoring data intercomparability for the Bulgarian – Romanian common stretch of the Danube River

PP2 – National Administration Romanian WatersCarmen 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%MEDIAN MIN. MAX. P25 P75 P10 P90

RAN

GE

STD.DE

V.

N-NH4

BG 110 0,16 0,13 0,18 0,14 0,00 0,86 0,08 0,22 0,03 0,30 0,86 0,12

RO 173 0,23 0,20 0,26 0,19 0,02 1,32 0,12 0,30 0,05 0,45 1,30 0,17

N-NO3

BG 111 1,48 1,36 1,60 1,39 0,37 4,61 1,07 1,90 0,77 2,21 4,24 0,64

RO 173 1,24 1,16 1,31 1,15 0,23 2,84 0,87 1,56 0,66 1,94 2,61 0,50

P-PO4

BG 95 0,065 0,057 0,072 0,060 0,000 0,250 0,040 0,080 0,020 0,110 0,250 0,035

RO 173 0,078 0,072 0,084 0,070 0,012 0,270 0,050 0,100 0,032 0,130 0,258 0,041

TP

BG 82 0,147 0,105 0,190 0,100 0,040 1,600 0,082 0,141 0,068 0,200 1,560 0,194

RO 166 0,117 0,093 0,140 0,090 0,018 1,930 0,070 0,130 0,053 0,170 1,912 0,151

T-test: the null hypothesis of H0: μx = μy (p=0.05)

BG VS RO

MEAN GROUP 1

MEAN GROUP 2

t-VALUE

DF p VALID GROUP 1

VALID GROUP 2

F-RATIO VARIANCES

p VARIANCES

N-NH40,16 0,23 -3,79 281 0,000182 110 173 1,96 0,000175

N-NO31,48 1,24 3,57 282 0,000420 111 173 1,63 0,004089

P-PO40,065 0,078 -2,663 266 0,008210 95 173 1,313 0,144475

TP 0,147 0,117 1,372 246 0,171338 82 166 1,648 0,007285

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

BG vs. RO (Pristol / Novo Selo)N-NO3

1.48

1.24

1.48

1.24

BG RO1.10

1.15

1.20

1.25

1.30

1.35

1.40

1.45

1.50

1.55

1.60

1.65

mg.

L-1

N-NO

3

1.48

1.24

Mean Mean±SE Mean±1.96*SE

BG vs. RO (Pristol / Novo Selo)Total Phosphorous

0.147

0.117

0.147

0.117

BG RO0.080

0.100

0.120

0.140

0.160

0.180

0.200

mg.L

-1 P

0.147

0.117

Mean Mean±SE Mean±1.96*SE

Basic descriptive statistics – Pristol / Novo Selo (simultaneous data)

PARA

M.

CO

UN

TRY

VALI

D N

MEA

N

CONF. -

95%

CONF. +

95%

MEDIA

NMIN. MAX. P25 P75 P10 P90

RAN

GE

STD.D

EV.

N-NH4

BG 20 0.08 0.06 0.11 0.07 0.02 0.26 0.04 0.12 0.02 0.14 0.24 0.06

RO 20 0.25 0.17 0.33 0.21 0.02 0.64 0.15 0.32 0.04 0.54 0.62 0.17

N-NO3

BG 21 1.57 1.33 1.80 1.80 0.75 2.70 1.10 1.90 0.83 2.02 1.95 0.52

RO 21 1.36 1.17 1.54 1.21 0.79 2.09 1.10 1.77 0.92 1.89 1.30 0.40

P-PO4

BG 22 0.06 0.055 0.075 0.06 0.020 0.110 0.050 0.080 0.040 0.080 0.09 0.022

RO 22 0.06 0.051 0.088 0.06 0.020 0.220 0.050 0.080 0.030 0.110 0.20 0.041

TP

BG 12 0.11 0.088 0.138 0.11 0.051 0.180 0.092 0.135 0.060 0.170 0.12 0.039

RO 12 0.12 0.080 0.177 0.11 0.050 0.330 0.085 0.160 0.053 0.170 0.28 0.076

T-test: the null hypothesis of H0: μx = μy (p=0.05)

BG VS RO

MEAN GROUP 1

MEAN GROUP 2

t-VALUE

DF p VALID GROUP 1

VALID GROUP 2

F-RATIO VARIANCES

p VARIANCES

N-NH4 0.08 0.25 -4.07 38 0.00022 20 20 0.06 0.17

N-NO3 1.57 1.36 1.47 40 0.14995 21 21 0.52 0.40

P-PO4 0.065 0.069 -0.448 42 0.65668 22 22 0.022 0.041

TP 0.113 0.129 -0.649 22 0.52305 12 12 0.039 0.076

Box-plots (Pristol / Novo Selo – simultaneous)

BG v s . RO (simultaneous data - Pristol / Novo Selo)N-NO3

1 .5 7

1 .3 6

1 .5 7

1 .3 6

BG RO1 .1 0

1 .2 0

1 .3 0

1 .4 0

1 .5 0

1 .6 0

1 .7 0

1 .8 0

1 .9 0

mg.

L-1

N-N

O3

1 .5 7

1 .3 6

Mean Mean±SE Mean±1.96*SE

BG vs RO (simultaneous data - Pristol / Novo Selo)TP

0.113

0.129

0.113

0.129

BG RO0.080

0.090

0.100

0.110

0.120

0.130

0.140

0.150

0.160

0.170

0.180

mg.L

-1 P

0.113

0.129

Mean Mean±SE Mean±1.96*SE

Pristol / Novo Selo

PARAM.COU

NTRY

VALI

D NMEAN MEDIAN MIN. MAX. P25 P75 P10 P90

RANG

E

STD.DEV

.

Water

temp.

RO 9 15.5 18.0 6.0 25.0 9.0 19.0 6.0 25.0 19.0 7.2

BG 9 16.1 17.0 3.3 26.6 9.6 22.5 3.3 26.6 23.3 8.6

SSRO 9 52.4 35.0 29.0 152.0 33.0 36.0 29.0 152.0 123.0 41.1

BG 9 73.3 70.0 55.0 90.0 68.0 82.0 55.0 90.0 35.0 11.7

DORO 9 8.6 7.8 6.1 11.1 7.6 9.7 6.1 11.1 5.0 1.7

BG 9 8.3 7.8 5.6 12.1 7.3 9.5 5.6 12.1 6.5 2.0

pHRO 9 8.07 8.07 7.92 8.21 8.02 8.12 7.92 8.21 0.29 0.09

BG 9 7.47 7.40 7.01 7.92 7.36 7.52 7.01 7.92 0.91 0.29

Cond.RO 9 385 366 346 457 363 418 346 457 111 39.7

BG 9 388 375 348 451 368 420 348 451 103 34.9

(2) Short – term data comparability January – September 2014 - 1

PARAM.COU

NTRY

VALI

D NMEAN MEDIAN MIN. MAX. P25 P75 P10 P90 RANGE STD.DEV

N-NH4

RO 9 0.053 0.051 0.0060 0.1710 0.0290 0.0530 0.0060 0.1710 0.165 0.04719

BG 9 0.089 0.072 0.0300 0.1830 0.0490 0.0920 0.0300 0.1830 0.153 0.05649

N-NO3

RO 9 0.020 0.022 0.0100 0.0290 0.0130 0.0250 0.0100 0.0290 0.019 0.00723

BG 9 0.019 0.019 0.0050 0.0320 0.0180 0.0270 0.0050 0.0320 0.027 0.00950

N-NO3RO 9 1.056 0.980 0.5500 1.6400 0.8300 1.4500 0.5500 1.6400 1.090 0.37290

BG 9 1.296 1.200 1.0300 1.6400 1.1000 1.4700 1.0300 1.6400 0.610 0.24269

TOTAL NRO 9 1.558 1.448 0.7860 2.2400 1.1940 2.0180 0.7860 2.2400 1.454 0.51179

BG 9 1.671 1.500 1.2000 2.5000 1.3000 1.9000 1.2000 2.5000 1.300 0.45057

P-PO4RO 9 0.036 0.037 0.0120 0.0700 0.0220 0.0480 0.0120 0.0700 0.058 0.01779

BG 9 0.039 0.034 0.0220 0.0550 0.0320 0.0530 0.0220 0.0550 0.033 0.01241

TOTAL PRO 9 0.051 0.049 0.0240 0.0750 0.0400 0.0650 0.0240 0.0750 0.051 0.01685

BG 9 0.068 0.056 0.0360 0.1690 0.0425 0.0715 0.0360 0.1690 0.133 0.04314

(2) Short – term data comparability January – September 2014 - 2 Pristol / Novo Selo

T-test: the null hypothesis of H0: μx = μy (p=0.05)

BG VS RO(MIDDLE)

MEAN GROUP 1

MEAN GROUP 2

t-VALUE DF p VALID GROUP 1

VALID GROUP 2

F-RATIO VARIANCES

p VARIANCES

w.temp. 15.500 16.077 -0.1543 16 0.8792 9 9 1.4537 0.609

SS 52.444 73.333 -1.4669 16 0.1617 9 9 12.297 0.001DO 8.5500 8.2888 0.29718 16 0.7701 9 9 1.4557 0.607pH 8.0677 7.4722 5.81390 16 0.0000 9 9 10.250 0.003Cond. 385 388 -0.1765 16 0.8620 9 9 1.2994 0.719N-NH4 0.0538 0.0890 -1.4310 16 0.1716 9 9 1.4332 0.622

N-NO2 0.0200 0.0196 0.08377 16 0.9342 9 9 1.7272 0.456

N-NO3 1.0567 1.296 -1.6175 16 0.1253 9 9 2.3607 0.245

N Total 1.5580 1.67111 -0.4976 16 0.6254 9 9 1.2901 0.727

P-PO4 0.0360 0.0395 -0.4643 15 0.6490 9 8 2.0551 0.358

P Total 0.0510 0.0681 -1.1031 15 0.2871 9 8 6.5517 0.016

Pristol / Novo Selo 2014 – Water temperature

Pristol / Novo Selo 2014 – Suspended Solids

(3) Momentary data comparability - June 2015

Chiciu / Silistra

Pristol / Novoselo

First approachPercentage difference between results (D)

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

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