EMODnet Chemistry 2 Quality Control inventory

Matteo Vinci and Alessandra Giorgetti OGS, Trieste

• Introduction

• Data Quality loop

• QC in the survey

• The survey

• Results

• Summary and Conclusions

If done well the management of data quality brings to a number of key advantages:

• Maintaining Common Standards

• Acquiring Consistency

• Ensuring Reliability

Quality check is done to…

“To ensure the data consistency within a single data set and within a collection of data sets and to ensure that the quality and errors of the data are apparent to the user who has sufficient information to assess its suitability for a task.” (IOC/CEC Manual, 1993)

One of the key activities of the network of EMODnet Chemistry is the work done for the quality upgrade and maintenance of the information managed. This work is done through several steps:

• Providing adequate metadata description to harvest data for resilience • Who• How• Where• When• What

• Flagging data after the quality check done by the collating institutes with SeaDataNet qualifier flags (L20 from BODC Vocab Library),

0 no quality control1 good value2 probably good value3 probably bad value4 bad value5 changed value6 value below detection7 value in excess8 interpolated value9 missing value

A value phenomenon uncertain

Data are checked, flagged and completed with metadata by National Collators

Making further Regional quality checks and reporting the results to the data originators/collators to keep the best copy of data available in the infrastructure.

One of the challenges of EMODnet Chemistry 2 project is related to the harmonization and improvement (where possible/ at least at Regional Level) of the QC/QA procedures for the harvested information. For this reasons two separate surveys have been circulated to the whole partnership:• one for the QC (ex-post : for controls done at data collection and

aggregation phase) – OGS data oriented• one for the QA/QC (ex-ante : for controls done at data production and

analytical methods implementation phase) – ISPRA analytical method oriented

Quality controls:The set of quality controls considered in this inventory were divided in some basic categories:

Position check:• Latitude and longitude have to be valid:

• Latitude in range -90 to 90• Longitude in range -180 to 180

• Position must not be on land. Observation latitude and longitude located in the Ocean

…

Date check:• Date and time of an observation has to be valid:• Year 4 digits (this can be tuned according to the data)• Month between 1 and 12• Day in range expected for month• Hour between 0 and 23• Minute between 0 and 59• …

Missing value check:• The data value is missing. A pre-defined number will represent the absent data

Range check:• Tests that data are within expected extremes encountered in the ocean• Tests that data are within expected extremes encountered in specific

Regions…

Spike check:• Tests differences between sequential measurements, where one

measurement is quite different than adjacent

Pre-existing statistics check:• Tests that data are within ranges defined by statistics of specific

areas/regions with reference to a specific climatology (Levitus, Medar …)

Visualization and manual check:• it is useful to visually screen data with the support of plots, to highlight

outliers and strange behaviors of data (caused for example by wrong measurement unit)

The Survey

The Survey consisted in an excel file with three tabs, one for each matrix (parameters of interest VS a basic list of the kind of check done). Partners were free to add further controls or parameters to the lists.

Total of 46 project participants 41 institutes involved in data collection.We received 33 responses from our partners, out of 41 data collectors.

Most of the involved institutes didn’t provide information about the reference (climatology) of their quality check…• was this request not properly highlighted?• are they using other statistics (e.g: not official climatologies linked to a

publication but statistics computed from their database)?

The Survey

The Survey –Results-

• All 33 institutes that replied perform quality checks for the water column matrix.

• 16 partners of the 33 are performing quality checks in the sediment matrix.

• 12 partners of the 33 are performing quality checks in the biota matrix

Number of institutes carrying out QC checks in the sediment matrix per parameter: the most checked seem to belong to the pesticides and heavy metals categories

The Survey –Results-

• Number of institutes carrying out QC checks in the water columnmatrix per parameter: the most checked seem to belong to the Fertilizers/Nutrients category

Parameter description N

1 Phosphate concentration parameters in the water column PHOS 312 Silicate concentration parameters in the water column SLCA 303 Ammonium concentration parameters in the water column AMON 304 Nitrate concentration parameters in the water column NTRA 295 Nitrite concentration parameters in the water column NTRI 296 Dissolved oxygen parameters in the water column DOXY 257 Chlorophyll pigment concentrations in the water column CPWC 248 Alkalinity, acidity and pH of the water column ALKY 219 Nitrate+nitrite concentration parameters in the water column NTRZ 20

10Dissolved total or organic phosphorus concentration in the water column TDPX 20

Parameter description n

1Pesticide concentrations in sediment Dichlorodiphenyltrichloroethane (DDT) 12

2 Metal concentrations in sediment Cadmium (Cd) 123 Metal concentrations in sediment Mercury (Hg) 114 Metal concentrations in sediment Lead (Pb) 11

5Pesticide concentrations in sediment Hexachlorobenzene (HCB)

10

6Concentration of polychlorobiphenyls (PCBs) in sediment samples PCBs 9

7Concentration of polycyclic aromatic hydrocarbons (PAHs) in sediment samples Anthracene (C14H10) 7

8Concentration of polycyclic aromatic hydrocarbons (PAHs) in sediment samples Fluoranthene (C16H10) 7

9 Carbon concentrations in sediment 5

10Concentration of other organic contaminants in sediment samples Tributyltin (TBT) 4

The Survey –Results-

Number of institutes carrying out QC checks in the biota matrix per parameter: the most checked seem to belong the heavy metals and pesticides categories

params checked n1 Metal concentrations in biota Cadmium (Cd) 102 Metal concentrations in biota Mercury (Hg) 93 Pesticide concentrations in biota Dichlorodiphenyltrichloroethane (DDT) 84 Pesticide concentrations in biota He1achlorobenzene (HCB) 85 Metal concentrations in biota Lead (Pb) 86 Concentration of polycyclic aromatic hydrocarbons (PAHs) in biota Anthracene (C14H10) 87 Concentration of polycyclic aromatic hydrocarbons (PAHs) in biota Fluoranthene (C16H10) 88 Concentration of polychlorobiphenyls (PCBs) in biota Concentration of polychlorobiphenyls (PCBs) in biota 89 Concentration of other organic contaminants in biota Tributyltin (TBTIN) 410 Concentration of other organic contaminants in biota Triphenyltin (TPT) 3

The Survey –Results- Numbers of specific QC checks for each parameter and matrix. Water Column:

• 23/33 for position checks (Fertilizers- -Ammonium concentration parameters in the water column)• 26/33 for date checks (Fertilizers- -Nitrite concentration parameters in the water column )• 22/33 for missing value checks (Fertilizers- -Ammonium concentration parameters in the water

column)• 29/33 for range checks ( Fertilizers- -Ammonium concentration parameters in the water column )• 19/33 for spike checks (Fertilizers- -Ammonium concentration parameters in the water column)• 10/33 for pre-existing statistics checks (Fertilizers- -Nitrate concentration parameters in the water

column)• 24/33 for visual and manual checks (Fertilizers- -Phosphate concentration parameters in the water

column)

The Survey –Results- Numbers of specific QC checks for each parameter and matrix. Sediment Matrix:

• 11/16 for position checks (Pesticides and biocides- Dichlorodiphenyltrichloroethane (DDT) -Pesticide concentrations in sediment)

• 11/16 for date checks (Pesticides and biocides- Dichlorodiphenyltrichloroethane (DDT) -Pesticide concentrations in sediment)

• 7/16 for missing value checks (Pesticides and biocides- Hexachlorobenzene (HCB) -Pesticide concentrations in sediment)

• 9/16 for range checks (Heavy metals- Mercury (Hg) -Metal concentrations in sediment)• 5/16 for spike checks (Pesticides and biocides- Dichlorodiphenyltrichloroethane (DDT) -Pesticide

concentrations in sediment)• 4/16 for pre-existing statistics checks (Pesticides and biocides- Dichlorodiphenyltrichloroethane (DDT)

-Pesticide concentrations in sediment)• 10/16 for visual and manual checks (Pesticidides and biocides- Dichlorodiphenyltrichloroethane (DDT)

-Pesticide concentrations in sediment)

?

The Survey –Results- Numbers of specific QC checks for each parameter and matrix. Biota Matrix:

• 8/12 for position checks (Pesticides and biocides Dichlorodiphenyltrichloroethane (DDT) Pesticide concentrations in biota)

• 10/12 for date checks (Heavy metals Cadmium (Cd) Metal concentrations in biota)• 7/12 for missing value checks (Heavy metals Cadmium (Cd) Metal concentrations in biota)• 10/12 for range checks (Heavy metals Cadmium (Cd) Metal concentrations in biota)• 2/12 for spike checks (Pesticides and biocides Dichlorodiphenyltrichloroethane (DDT) Pesticide

concentrations in biota)• 3/12 for pre-existing statistics checks (Pesticides and biocides Dichlorodiphenyltrichloroethane (DDT)

Pesticide concentrations in biota)• 9/12 for visual and manual checks (Heavy metals Mercury (Hg) Metal concentrations in biota)

?

The Survey –Summary/Conclusions-

• As expected there is:• a considerably higher number of institutes dealing with water column

measured parameters (33/33 institutes)• followed by the sediment matrix parameters (16/33 institutes) • and biota matrix parameters (12/33 institutes)

• For the water column matrix the five parameters harvested and most checked seem to belong to the Fertilizers/Nutrients category. In the water column the range check (29/33) results the most common kind of control done

• For the sediment matrix the five parameters harvested and most checked seem to belong to the pesticides and heavy metals categories. In the sediment matrix the position and date checks (11/16) are the most common kind of control done

• For the biota matrix the five parameters harvested and most checked seem to belong to the pesticides and heavy metals categories. In the biota matrix the date and range checks (10/12) are the most common kind of control done

The Survey –Summary/Conclusions-

• Following the results there is still a number of basic quality checks that are not performed. The implementation of this position and date check, missing value and range check should be a mandatory action

• We should evaluate the meaning of a spike check for sediment and biota matrixes where unforeseen really high values are possible (hot spots) and the kind of algorithm used for the water column to check spike can’t be used

• Some steps in the upgrade of the quality control within the EMODnet Chemistry activities can be:

• Sharing and synchronization of ranges and pre-existing statistics used for the data check in the different regions (see report “Methodology for data QA/QC and DIVA products”)

• Upgrade of QC ranges and statistics with EMODnet database (coastal vs open sea)

http://www.emodnet-chemistry.eu/

Alessandra Giorgetti : agiorgetti@ogs.trieste.itMatteo Vinci : mvinci@ogs.trieste.it

Thanks for your attention !Questions?