Long-Term Trends in Cloud and Rain Chemistry on Mount Washington, New Hampshire

Murray, Georgia; Kimball, Kenneth D.; Hill, L. Bruce; Hislop, Jane E.; Weathers, Kathleen C.

doi:10.1007/s11270-013-1653-7

Cited by 12 publications

(9 citation statements)

References 30 publications

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“…Calculated aerosol radiative forcing is much more sensitive to pH if a temporal change in cloud water pH is assumed to have occurred between 1970 and 2009 (Figure ). On a regional scale pH has been observed to have changed by 1.0 unit (e.g., United States and Europe; Aleksic et al (); Murray et al (); Vet et al (); Schwab et al ()). We assess the impact of such temporal changes in pH by comparing the results from simulations using different global cloud water pH values over the period 1970 to 2009.…”

Section: Resultsmentioning

confidence: 99%

“…The pH varies from 3 to 7 across coastal marine environments and continental areas of the United States, Europe, China, and India (Aleksic et al, ; Benedict et al, ; Budhavant et al, ; Collett et al, ; Murray et al, ; Plessow et al, ; Sun et al, ). Measurements show that since the mid‐1980s cloud water pH has increased from 4 to ~5 in the northeastern United States due to reductions in emissions of acidifying gases (Aleksic et al, ; Murray et al, ; Schwab et al, ). However, there are no measurements over remote regions downwind of source locations where SO 2 oxidation is likely to take place after long‐range transport.…”

Section: Introductionmentioning

confidence: 99%

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The Impact of Changes in Cloud Water pH on Aerosol Radiative Forcing

Turnock

Mann

Woodhouse

et al. 2019

Geophysical Research Letters

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Oxidation of sulfur dioxide (SO2) in cloud water by reaction with ozone is an important sulfate aerosol formation mechanism and strongly dependent on the acidity of cloud water. Decadal reductions in Northern Hemisphere sulfur emissions have contributed to higher cloud water pH, thereby altering sulfate formation rates. Here we use a global composition‐climate model to show that changes in cloud water pH over the 1970–2009 period strongly affects the aerosol particle size distribution, cloud condensation nuclei concentrations, and the magnitude of aerosol radiative forcing. The simulated all‐sky aerosol radiative forcing (1970–2009) over the North Atlantic is +1.2 W m−2 if pH remains constant at 5.0, as in many climate models. However, the forcing increases to +5.2 W m−2 if pH is assumed to increase by 1.0 unit over this period. Global composition climate models need to account for variations in cloud water pH to improve the representation of sulfate aerosol formation and aerosol radiative effects.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Impact of Changes in Cloud Water pH on Aerosol Radiative Forcing

Turnock

Mann

Woodhouse

et al. 2019

Geophysical Research Letters

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“…Because fog droplets have been shown to be effective scavengers of aerosol particles and trace gases, they can provide an indication of local or regional air quality and can reveal changes over time if sampling occurs over an extended period. There have been a number of multi-year cloud water studies at high elevation sites to compile long-term cloud water composition data or to quantify monthly, seasonal, or yearly trends (Yamaguchi et al, 2015;Deguillaume et al, 2014;Gioda et al, 2013;Murray et al, 2013;Vaitilingom et al, 2012;Aleksic et al, 2009;Aikawa et al, 2007;Anderson et al, 2006;Tago et al, 2006;Baumgardner et al, 2003;Anderson et al, 1999;Acker et al, 1995;Schemenauer et al, 1995;Mohnen and Kadlecek, 1989). In most of these studies stratus, frontal, or orographically enhanced clouds were targeted.…”

Section: Introductionmentioning

confidence: 99%

Radiation fog chemical composition and its temporal trend over an eight year period

Straub

2017

Atmospheric Environment

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Radiation fog samples have been collected at a rural site in Central Pennsylvania from 2007 through 2015 in order to document chemical composition, assess concentration changes over time, and to provide insight into emission sources that influence the region. The collection of samples over multiple years makes this one of the few long duration radiation fog studies that have been completed.During the course of the campaign, 146 samples were obtained and analyzed for pH, major inorganic ions, low molecular weight organic acids, total organic carbon (TOC) and total nitrogen (TN).Ammonium (median concentration = 209 µN), sulfate (69 µN), calcium (51 µN), and nitrate (31 µN) were the most abundant inorganic ions, although these were present at much lower concentrations than for radiation fog studies conducted in other locations. Organic acids, of which formate (20 µM) and acetate (21 µM) were the most abundant, were closer in magnitude to measurements made during previous studies. Organic acids accounted for 15% of TOC, which had a median concentration of 6.6 mgC l -1 . The median concentration of TN was 3.6 mgN l -1 , 18% of which was determined to be organic nitrogen.Statistically significant decreasing trends from 2007 to 2015 were noted for sulfate, ammonium, chloride, and nitrate. For the same period, an increase in pH was observed. Seasonal trends were identified for a number of species as well. The partitioning of ammonia between the gas and aqueous phases was also investigated and found to deviate significantly from equilibrium.

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“…Wet deposition (where present) is now known to be the predominant source of deposition for many atmospheric radionuclides and pollutant metals. 21,1 Earlier interpretations of aerosol behavior may also fail to describe contemporary observations due to a reduction in atmospheric SO 4 2− and concomitant increase in rainwater pH which has been observed in some regions of the U.S. over recent decades, 22,23 and which may influence both speciation 21 and sorption behavior 24 of relevant metals.…”

Section: Introductionmentioning

confidence: 99%

Quantitative Retention of Atmospherically Deposited Elements by Native Vegetation Is Traced by the Fallout Radionuclides ⁷Be and ²¹⁰Pb

Landis

Renshaw

Kaste

2014

Environ. Sci. Technol.

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Atmospheric deposition is the primary mechanism by which remote environments are impacted by anthropogenic contaminants. Vegetation plays a critical role in intercepting atmospheric aerosols, thereby regulating the timing and magnitude of both contaminant and nutrient delivery to underlying soils. However, quantitative models describing the fate of atmospherically derived elements on vegetation are limited by a lack of long-term measurements of both atmospheric flux and foliar concentrations. We addressed this gap in understanding by quantifying weekly atmospheric deposition of the naturally occurring radionuclide tracers (7)Be and (210)Pb, as well as their activities in leaves of colocated trees, for three years in New Hampshire, U.S. The accumulation of both (7)Be and (210)Pb in deciduous and coniferous vegetation is predicted by a model that is based solely on measured atmospheric fluxes, duration of leaf exposure, and radioactive decay. Any "wash off" processes that remove (7)Be and (210)Pb from foliage operate with a maximum half-time of greater than 370 days (P > 99%), which is an order of magnitude longer than previously assumed. The retention of both (7)Be and (210)Pb on leaves is thus quantitative and permanent, coupling the fate of (7)Be, (210)Pb and similar atmospheric species to that of the leaf matter itself. These findings demonstrate that the long-standing paradigm of a short "environmental half-life" for atmospheric contaminants deposited on natural surfaces must be re-evaluated.

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Long-Term Trends in Cloud and Rain Chemistry on Mount Washington, New Hampshire

Cited by 12 publications

References 30 publications

The Impact of Changes in Cloud Water pH on Aerosol Radiative Forcing

The Impact of Changes in Cloud Water pH on Aerosol Radiative Forcing

Radiation fog chemical composition and its temporal trend over an eight year period

Quantitative Retention of Atmospherically Deposited Elements by Native Vegetation Is Traced by the Fallout Radionuclides ⁷Be and ²¹⁰Pb

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Long-Term Trends in Cloud and Rain Chemistry on Mount Washington, New Hampshire

Cited by 12 publications

References 30 publications

The Impact of Changes in Cloud Water pH on Aerosol Radiative Forcing

The Impact of Changes in Cloud Water pH on Aerosol Radiative Forcing

Radiation fog chemical composition and its temporal trend over an eight year period

Quantitative Retention of Atmospherically Deposited Elements by Native Vegetation Is Traced by the Fallout Radionuclides 7Be and 210Pb

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Product

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Quantitative Retention of Atmospherically Deposited Elements by Native Vegetation Is Traced by the Fallout Radionuclides ⁷Be and ²¹⁰Pb