Traceability for mercury measurements

Short Name: MeTra, Project Number: ENV51
Mercury

Improved mercury measurements: Tackling new requirements for mercury measurements 


Highly toxic mercury is released into the atmosphere in several forms - elemental mercury, particlebound mercury, or oxidised mercury - from burning fossil fuels, forest fires or energy efficient compact fluorescent lights. Its form governs the distance it travels and its ability to accumulate in biological systems. To control and reduce mercury emissions the EU has introduced a raft of legislation supporting the goals of the Minamata Convention.

 

Mercury is reactive, volatile, difficult to store and handle, making it extremely challenging to measure as it sticks to many surfaces. Existing measurement methods need better links to the SI units and increased accuracy to enable improved monitoring of abatement effectiveness and mercury trends in the environment.

 

This project developed a calibration system for mercury in air and used this to calibrate environmental monitoring sensors, and optimised biota analysis procedures to remove biases from inter-species fat content variation. This project builds on the outcomes of EMRP project Emerging requirements for measuring pollutants from automotive exhaust emissions.


The project:

  • Developed an SI traceable mercury-in-air calibration system based on accurately determining mercury vaporisation weight loss to provide a potential replacement for currently used equations
  • Compared NMI calibration methods using an SI traceable transfer instrument as a first step towards international measurement equivalence
  • Optimised and validated procedures for determining the mercury content in fish and used these to establish inter-species differences resulting from variations in fat content or habitat
  • Evaluated the performance of innovative low-cost mercury-in-air monitoring sensors, demonstrating their suitability for use in determining atmospheric traces of mercury.

 

This project made significant progress towards the introduction of a measurement infrastructure based on the SI units for measurements of mercury, thus providing a potential alternative to the current use of equations of state. New measurement methods and procedures are now available for determining mercury traces in atmospheric precipitation and seawater, whilst a project derived digestion method for mercury in particulate matter has removed reliance on hazardous hydrofluoric acid. This has been included as an annex to a European Normative standard. The project’s low-cost yet highly sensitive prototype sensor, based on nanostructured materials, has been trialled at 5 Global Mercury Observation System monitoring sites, successfully demonstrating its potential for greater adoption in environmental mercury monitoring.

 

Collaborations between the project and the IAEA Marine Environmental Studies Laboratory, providers of technical support to several UN agencies, have enabled the uptake of accurate production procedures for mercury containing biota reference materials, whilst a constant interaction with NIST and the US EPA has achieved an international consensus for mercury measurement standards in air. These are important steps in the generation of a greater international harmonisation for mercury measurements.

Project website