Speciated mercury at marine, coastal, and inland sites in New England-Part 1: Temporal variability

40Citations
Citations of this article
30Readers
Mendeley users who have this article in their library.

Abstract

A comprehensive analysis was conducted using long-term continuous measurements of gaseous elemental mercury (Hg 0), reactive gaseous mercury (RGM), and particulate phase mercury (Hg P) at coastal (Thompson Farm, denoted as TF), marine (Appledore Island, denoted as AI), and elevated inland (Pac Monadnock, denoted as PM) sites from the AIRMAP Observatories in southern New Hampshire, USA. Decreasing trends in background Hg 0 were identified in the 7.5-and 5.5-yr records at TF and PM with decline rates of 3.3 parts per quadrillion by volume (ppqv) yr -1 and 6.3 ppqv yr -1, respectively. Common characteristics at these sites were the reproducible annual cycle of Hg 0 with its maximum in winter-spring and minimum in fall, comprised of a positive trend in the warm season (spring-early fall) and a negative one in the cool season (late fall-winter). Year-to-year variability was observed in the warm season decline in Hg 0 at TF varying from a minimum total (complete) seasonal loss of 43 ppqv in 2009 to a maximum of 92 ppqv in 2005, whereas variability remained small at AI and PM. The coastal site TF differed from the other two sites with its exceptionally low levels (as low as below 50 ppqv) in the nocturnal inversion layer possibly due to dissolution in dew water. Measurements of Hg 0 at PM exhibited the smallest diurnal to annual variability among the three environments, where peak levels rarely exceeded 250 ppqv and the minimum was typically 100 ppqv. It should be noted that summertime diurnal patterns at TF and AI were opposite in phase indicating strong sink(s) for Hg 0 during the day in the marine boundary layer, which was consistent with the hypothesis of Hg 0 oxidation by halogen radicals there. Mixing ratios of RGM in the coastal and marine boundary layers reached annual maxima in spring and minima in fall, whereas at PM levels were generally below the limit of detection (LOD) except in spring. RGM levels at AI were higher than at TF and PM indicating a stronger source strength in the marine environment. Mixing ratios of Hg P at AI and TF were close in magnitude to RGM levels and were mostly below 1 ppqv. Diurnal variation in Hg P was barely discernible at TF and AI in spring and summer. Higher levels of HgP were observed during the day, while values that were smaller, but above the LOD, occurred at night. © 2012 Author(s).

Cite

CITATION STYLE

APA

Mao, H., & Talbot, R. (2012). Speciated mercury at marine, coastal, and inland sites in New England-Part 1: Temporal variability. Atmospheric Chemistry and Physics, 12(11), 5099–5112. https://doi.org/10.5194/acp-12-5099-2012

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Save time finding and organizing research with Mendeley

Sign up for free