A comparison of data quality control protocols for atmospheric mercury speciation measurements

Abstract

Significant advances in the measurement of atmospheric mercury species have been made in the past 10 years yet limited protocols on quality control (QC) and assurance on this data have been published in the literature. Recently, considerable work has been done to develop quality control and assurance programs within North America. Environment Canada and the National Atmospheric Deposition Network (NADP) independently developed programs, RDMQ™ and AMQC, respectively, to QC atmospheric mercury speciation data (including gaseous elemental mercury (GEM), reactive gaseous mercury (RGM) and mercury associated to particles (PHg)). These 2 programs were assessed by the criteria on which the data is QCed and comparability of the final data products. Results show that the criteria used to flag data compare well within the 4 tested sites and that the number of flags for each criterion is generally comparable. The QC programs were applied to 2 distinct data sets and the final QCed data was compared. From a mid-latitude site, the final data sets compare very well and showed there to be a 0.3, 8.6 and 15% difference in the mean GEM, RGM and PHg concentrations post QC of each program. It is recommended that either the RDMQ or the AMQC programs be employed for a typical mid-latitude site. When the QC programs were applied to highly variable data, the data do not compare as well for RGM and PHg. Results showed a 2.7, 27 and 33% difference in the mean GEM, RGM and PHg concentrations, respectively, post QC of each program. It is recommended that RDMQ be used for data that is highly variable with high RGM/PHg concentrations as it allows for more manual correction over the QCed data. This investigation of 2 QC programs produced comparable data and that either of these programs can be used as standard methods for the quality control of atmospheric mercury speciation data.

Comparison of mercury concentrations measured at several sites in the Southern Hemisphere

“…Contributions of deviations from an ideal performance, such as slow deactivation of the traps, difference between the concentrations from the two traps, contamination of the switching valves and traps, and leaks (Steffen et al, 2012), are difficult to quantify. Thus we take published results of Tekran instrument intercomparisons as a measure of practically achievable systematic uncertainty.…”

Concentration-weighted trajectory approach to identifying potential sources of speciated atmospheric mercury at an urban coastal site in Nova Scotia, Canada

“…The software flags data using multiple performance checks including baseline stability, calibration response, contamination, sample volume, and variability between dual sampling cartridges. These data QA-QC checks along with rigorous sampling and maintenance protocols have contributed to a quality control standard for atmospheric mercury species measurements (Steffen et al, 2012).…”

How important is biomass burning in Canada to mercury contamination?

“…The American sites are operated as part of the Atmospheric Mercury Network (AMNet, Steffen et al, 2012). The Canadian sites are part of the Environment and Climate Change Canada's (ECCC's) Canadian Atmospheric Mercury Measurement Network (CAMNet), the Canadian Air and Precipitation Monitoring Network (CAPMoN), the Joint Oil Sands Monitoring Program 15 (JOSM), the Northern Contaminants Program (NCP), the Canadian Clean Air Regulatory Agenda (CARA), and two special studies (Cole et al, 2014).…”