The aim of WP2 is to develop, evaluate and compare different methods of measuring oxidised Hg. This will include traceable measurement (detection) using sorbent traps of the most environmentally relevant oxidised Hg species in stack gas emissions and in the atmosphere. Sorbent trap methods will be developed for the measurement of Hg(II) (the most common form of oxidised Hg) captured using a species specific methodology and Hg bound to particulate matter (PM). These methods will then be used to investigate interspecies and isotopic shifting conversion/fractionation arising from sample preparation and storage in WP3, and in the on‑line Hg field measurements in WP4.
The determination of oxidised Hg species i.e. Hg(II) is a significant challenge as it is present in the atmosphere at ultra-low concentrations (pg/m3), and in stack emissions, in very complex matrices, at µg/m3 levels. Several Hg(II) selective trapping techniques currently exist for measuring oxidised Hg and are commonly used with relevant elemental detectors. However, this WP will provide a much needed comparison of these methods in order to identify the metrological merits of each and to produce a ‘Good practice’ guide for Hg sample preparation and species interconversion.
The aims of the tasks in WP2 are to:
Task 2.1: develop and compare methods for determining selectively trapped gaseous Hg(II) at environmentally relevant concentrations. This will be undertaken using different sample introduction techniques for Hgtot and Hg speciation (e.g. gas chromatography (GC) and laser ablation (LA)) coupled with element specific detectors (e.g. cold vapour atomic absorption spectrometry (CV AAS), cold vapour atomic fluorescence spectrometry (CV AFS) and inductively coupled plasma mass spectrometry (ICP-MS). Atmospheric-pressure chemical ionisation mass spectrometry (APCI-MS) will also be used for direct Hg species identification.
Task 2.2: develop methods for measuring Hg(II) on particulate matter (PM) via the determination of the Hgtot and by species-specific analysis.
Task 2.1: Measurement of selectively trapped gaseous Hg(II) at environmental concentrations
The aim of this task is to develop and compare methods for determining selectively trapped gaseous Hg(II) at environmentally relevant concentrations i.e. in the atmosphere (pg/m3 levels) and in stack gas emissions (µg/m3). This will be undertaken by determining Hgtot with bulk (i.e. elution, digestion or LA) and species-specific analysis (i.e. GC) using conventional element specific detection techniques such as CV AAS, CV AFS and ICP-MS); and novel techniques such as APCI-MS. The calibration methods and the reference gas standards from Tasks 1.1-1.3 will be used to evaluate the performance and to compare the methods developed in this task.
The use of passive biomonitors (e.g. lichens and pine needles) as proxies for Hg speciation and isotopic signatures representing past atmospheric Hg deposition and fate will also be studied using either rain water samples or selected samples stored in the ESB.
In A2.1.7, UBA will subcontract technical support work to a company that specialises in sample preparation (i.e. cryomilling, sample storage in liquid nitrogen). This work will be subcontracted to Fraunhofer IME and Eurofins Hamburg and is required as the consortium does not have the necessary skills/expertise for such sample preparation.
| Activity number | Activity description | Partners (Leadinbold) |
|---|---|---|
| A2.1.1 |
JSI, LGC and UPPA will select at least 3 of the most common/widely used methods for the selective determination of Hg(II) and Hg(0), in the gas phase, that has been selectively trapped in denuders, sorbent traps and impinger solutions. JSI will then evaluate these methods for determining Hgtot /Hg(II) in materials specific for Hg(II) trapping via selective reduction/derivatisation and/or thermal desorption-CV-AAS/CV-AFS/MS detection. LGC will evaluate these methods via elution/acid leaching and subsequent ICP-MS. JSI will investigate a method for Hg(II) species specific determination within gaseous traps using APCI-MS. In parallel, LGC and UPPA will evaluate methods of derivatisation, and pre-concentration for Hg(II) by cryotrapping and analysis by GC-ICP-MS or by liquid chromatography (LC)-ICP-MS. LGC and UPPA will investigate whether LA-ICP-MS can be used for the direct sampling and quantification of Hgtot from gaseous Hg(II) selective materials (i.e. denuders, sorbent traps, and particles on filters from A2.2.8). |
JSI, LGC, UPPA |
| A2.1.2 |
LGC, UPPA, and CENAM will investigate the mercury species interconversion that occurs during the measurement steps in the methods from A2.1.1 using Hg isotopically enriched compounds (e.g. Hg(0), Hg-halides). JSI will also do this, but using a radioactively labelled Hg tracer (i.e. 197-Hg prepared from enriched 196-Hg). Methods to minimise species interconversion will be investigated by LGC, JSI, UPPA and CENAM and where significant species conversion does occur, correction methods will be developed. The results of this activity will be used in A2.2.5 to produce D5. |
LGC, UPPA, CENAM, JSI |
| A2.1.3 | LGC, with support from JSI, VSL, VTT, PSA, UPPA and CENAM, will evaluate the performance of the methods from A2.1.1 and A2.1.2 for determining selectively trapped gaseous Hg(II) at environmentally relevant concentrations using the calibration methods and reference gas standards from A1.1.4 and A1.3.3, and the artefact free sampling methods from A3.2.3. | LGC, JSI, VSL, VTT, PSA, UPPA, CENAM |
| A2.1.4 | Using input from A2.1.1-A2.1.3, UPPA and JSI will develop SI traceable methods to accurately determine Hgtot isotopic ratio signatures using MC-ICP-MS, from species specific Hg(II) and Hg(0) gases from denuders, sorbent traps, impinger solutions (from A2.2.8). As part of this, UPPA and JSI will develop mass bias correction procedures to overcome mass discrimination. | UPPA, JSI |
| A2.1.5 | Using the results of A2.1.1-A2.1.4, LGC, with support from JSI, VSL, CENAM, PSA, VTT and UPPA, will produce a report on the comparison of different methods for measuring oxidised Hg (Hg(II)); including methods to accurately compare total mercury (Hgtot) concentrations in generated standard gases for elemental mercury Hg(0) and oxidised mercury (Hg(II)). | LGC, JSI, VSL, CENAM, PSA, VTT, UPPA |
| A2.1.6 | LGC, with support from JSI, VSL, CENAM, PSA, VTT and UPPA, will review the report from A2.1.5, and the coordinator will then submit it to EURAMET as D3 ‘Report on the comparison of different methods for measuring oxidised Hg (Hg(II)); including methods to accurately compare total mercury (Hgtot) concentrations in generated standard gases for elemental mercury Hg(0) and oxidised mercury (Hg(II)). | LGC, JSI, VSL, CENAM, PSA, VTT, UPPA |
| A2.1.7 |
UBA, UPPA and JSI will investigate the use of biomonitors (e.g. lichens and pine needles) as passive monitoring samples for Hg speciation and isotopic signatures representing Hg atmospheric sources and fate. Samples from the ESB at UBA will be used as well as rain water samples from the national air monitoring networks of UBA, UPPA and JSI as an additional source of Hg in environmentally relevant passive samples. UBA will subcontract the work in this activity to Fraunhofer IME and Eurofins Hamburg. This subcontracted work is required for technical support from a specialist company for sample preparation (i.e. cryomilling, sample storage in liquid nitrogen). |
UBA, UPPA, JSI |
Task 2.2: Measurement of Hg(II) on particulate matter (PM)
The aim of this task is to develop methods for measuring Hg(II) on PM via the determination of the Hgtot and by species-specific analysis. PM is an integral part of an air sample from the atmosphere or from stack gas emissions and is usually removed prior to the separation of Hg(0) and Hg(II) in the gaseous phase. However, due to the reactivity of Hg(II) in the gaseous phase a substantial proportion of Hg(II) is absorbed/bound on PM and thus species specific measurements for evaluating origin discrimination and Hg species interconversion are needed.
In A2.2.9, UBA will subcontract technical support work to a company that specialises in sample preparation (i.e. cryomilling, sample storage in liquid nitrogen). This work will be subcontracted to Fraunhofer IME and Eurofins Hamburg and is required as consortium does not have the necessary skills/expertise for such sample preparation. In addition, CENAM will subcontract a technical expert to undertake an investigation of field methods for total mercury and mercury II in A2.2.1. This work will be subcontracted as CENAM does not have the necessary skills/expertise for the validation of field methods. Furthermore, as the validation has to be undertaken in Mexico, the other partners in the consortium cannot undertake the work.
| Activity number | Activity description | Partners (Lead in bold) |
|---|---|---|
| A2.2.1 |
LGC and TUBITAK will evaluate the suitability of the novel digestion and subsequent ICP-MS methods developed in A2.1.2 for determining the Hgtot content within filter-captured particles i.e. PM. The methods will be adapted as necessary. UPPA will evaluate combustion and acid digestion followed by conventional CV AAS/AFS for determining the Hgtot content within PM. The samples, to be used with the methods, will be denuders, sorbent traps and particles on filters and they will be provided by UPPA and JSI. CENAM will investigate the stability of Hgtot and Hg(II) in PM using samples of PM emitted from coal-fired power plants. The subsequent validation (i.e. proficiency testing) will be undertaken only for Hgtot in particle matter. CENAM will subcontract this work as it does not have the necessary skills/expertise for the validation. Furthermore as the validation has to be undertaken in Mexico, the other partners cannot undertake the work. |
LGC, TUBITAK, UPPA, CENAM, JSI |
| A2.2.2 |
Building on work in EMRP JRP ENV51 MeTra, LGC will further develop novel LA-ICP-MS for the direct sampling and quantification of Hgtot in filter-captured particles i.e. PM in order to reduce the uncertainty of the measurement from 50 % to 15 %. The samples, to be used with the methods, will be denuders, sorbent traps and particles on filters and they will be provided by UPPA and JSI. |
LGC, UPPA, JSI |
| A2.2.3 |
JSI will investigate methods for Hg(II) species specific determination at environmentally relevant concentrations (i.e. typically a few tens of pg∙m -3) for PM bound Hg(II) using the novel APCI-MS methodology. In parallel, LGC and UPPA will evaluate methods for derivatisation, pre-concentration by cryotrapping and subsequent GC-ICP-MS or LC-ICP-MS for Hg(II) species specific determination at environmentally relevant concentrations for PM bound Hg(II). The samples, to be used with the methods, will be denuders, sorbent traps and particles on filters and they will be provided by UPPA and JSI. |
JSI, LGC, UPPA |
| A2.2.4 |
JSI will investigate methods for selectively determining Hg(0) and Hg(II) absorbed to PM using temperature desorption and subsequent MS detection. The samples, to be used with the methods, will be denuders, sorbent traps and particles on filters and they will be provided by UPPA and JSI. |
JSI, UPPA |
| A2.2.5 |
LGC, TUBITAK, UPPA and CENAM will investigate species interconversion during sample preparation and extraction for GC-ICP-MS analysis of particle bound (PM) Hg(II) using Hg isotopically enriched compounds. Methods to minimise conversion will be investigated and where significant conversion does occur, correction methods will be developed. The samples, to be used with the methods, will be denuders, sorbent traps and particles on filters and they will be provided by UPPA and JSI. |
LGC, TUBITAK, UPPA, CENAM, JSI |
| A2.2.6 | LGC, TUBITAK, UPPA, CENAM and JSI will use the results from A2.1.3, A2.2.1-A2.2.5, and A3.2.5 to produce a good practice guide for Hg sample preparation and interspecies conversion. | LGC, TUBITAK, UPPA, CENAM, JSI |
| A2.2.7 | LGC, with support from TUBITAK, UPPA, CENAM and JSI, will review the good practice guide from A2.2.6, and the coordinator will then submit it to EURAMET as D5 ‘Good practice guide for Hg sample preparation and interspecies conversion correction’. | LGC, TUBITAK, UPPA, CENAM, JSI |
| A2.2.8 |
UPPA and JSI will develop traceable methods to accurately determine Hgtot isotopic ratio signatures in PM using femto-Sec-LA-ICP-MS or MC-ICP-MS. The samples, to be used with the methods, will be denuders, sorbent traps, and particles on filters and they will be provided by UPPA and JSI. |
UPPA, JSI |
| A2.2.9 |
UPPA, JSI, TUBITAK and LGC will test the methods developed in A2.2.1-A2.2.5 and A2.2.8 on at least 12 filters obtained from UBA from at least 2 stations from their air monitoring network. UBA will subcontract the work in this activity to Fraunhofer IME and Eurofins Hamburg. This subcontracted work is required for technical support from a specialist company for sample preparation (i.e. cryomilling, sample storage in liquid nitrogen). UPPA, JSI, UBA, TUBITAK, LGC and CENAM will summarise the results together with those from A2.1.7 and A3.1.4 in a report on accurate bulk species specific isotope ratio measurements to determine Hg migration pathways, its origin and species interconversion including the use of biomonitors as passive monitors for Hg speciation and isotopic signatures representing the origin and fate of atmospheric Hg. |
UPPA, JSI, UBA, TUBITAK, LGC, CENAM |
| A2.2.10 | UPPA, with support from JSI, UBA, TUBITAK, LGC and CENAM will review the report from A2.2.9, and the coordinator will then submit it to EURAMET as D4 ‘Report on bulk species specific isotope ratio measurements to determine Hg migration pathways, its origin and species interconversion including the use of biomonitors as passive monitors for Hg speciation and isotopic signatures representing the origin and fate of atmospheric Hg’. | UPPA, JSI, UBA, TUBITAK, LGC, CENAM |
