Dependence of Daily Aerosol Wet Deposition on Precipitation at Appalachian Mountains Site in the United States

Abstract. Atmospheric mercury is a toxic air and water pollutant that is of significant concern because of its effects on human health and ecosystems. A mechanistic representation of the atmospheric mercury cycle is developed for the state-of-the-art global climate-chemistry model, CAM-Chem (Community Atmospheric Model with Chemistry). The model simulates the emission, transport, transformation and deposition of atmospheric mercury (Hg) in three forms: elemental mercury (Hg(0)), reactive mercury (Hg(II)), and particulate mercury (PHg). Emissions of mercury include those from human, land, ocean, biomass burning and volcano related sources. Land emissions are calculated based on surface solar radiation flux and skin temperature. A simplified air–sea mercury exchange scheme is used to calculate emissions from the oceans. The chemistry mechanism includes the oxidation of Hg(0) in gaseous phase by ozone with temperature dependence, OH, H2O2 and chlorine. Aqueous chemistry includes both oxidation and reduction of Hg(0). Transport and deposition of mercury species are calculated through adapting the original formulations in CAM-Chem. The CAM-Chem model with mercury is driven by present meteorology to simulate the present mercury air quality during the 1999–2001 periods. The resulting surface concentrations of total gaseous mercury (TGM) are then compared with the observations from worldwide sites. Simulated wet depositions of mercury over the continental United States are compared to the observations from 26 Mercury Deposition Network stations to test the wet deposition simulations. The evaluations of gaseous concentrations and wet deposition confirm a strong capability for the CAM-Chem mercury mechanism to simulate the atmospheric mercury cycle. The results also indicate that mercury pollution in East Asia and Southern Africa is very significant with TGM concentrations above 3.0 ng m−3. The comparison to wet deposition indicates that wet deposition patterns of mercury are more affected by the spatial variability of precipitation. The sensitivity experiments show that 22% of total mercury deposition and 25% of TGM concentrations in the United States are resulted from domestic anthropogenic sources, but only 9% of total mercury deposition and 7% of TGM concentrations are contributed by transpacific transport. However, the contributions of domestic and transpacific sources on the western United States levels of mercury are of comparable magnitude.

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Polycentropus dinkinsorum (Trichoptera: Polycentropodidae), a newly described caddisfly species from the southern Appalachian Mountains, USA

Zootaxa ◽

10.11646/zootaxa.4853.1.8 ◽

2020 ◽

Vol 4853 (1) ◽

pp. 126-132

Author(s):

ALEXANDER B. ORFINGER ◽

DAVID A. ETNIER

Keyword(s):

United States ◽

Newfoundland And Labrador ◽

Male Genitalia ◽

Appalachian Mountains ◽

The United States ◽

Species Group ◽

Canadian Province ◽

Southern Appalachian Mountains ◽

Southern Appalachian ◽

First Time

We describe here a new caddisfly species of the genus Polycentropus (Trichoptera: Polycentropodidae) based on males from numerous localities throughout the southern Appalachian Mountains of the United States. Polycentropus dinkinsorum is a member of the P. confusus Species Group and is readily separated from its congeners based on aspects of the male genitalia. A diagnosis and illustrations of male genitalia are provided. In addition, P. pentus Ross 1941 is reported for the first time from the Canadian province of Newfoundland and Labrador.

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Increasing importance of deposition of reduced nitrogen in the United States

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1525736113 ◽

2016 ◽

Vol 113 (21) ◽

pp. 5874-5879 ◽

Cited By ~ 165

Author(s):

Yi Li ◽

Bret A. Schichtel ◽

John T. Walker ◽

Donna B. Schwede ◽

Xi Chen ◽

...

Keyword(s):

United States ◽

Nitrogen Deposition ◽

Wet Deposition ◽

Inorganic Nitrogen ◽

Rapid Development ◽

The United States ◽

Natural Ecosystems ◽

Nitrogen Emissions ◽

Reduced Nitrogen ◽

Reactive Nitrogen Emissions

Rapid development of agriculture and fossil fuel combustion greatly increased US reactive nitrogen emissions to the atmosphere in the second half of the 20th century, resulting in excess nitrogen deposition to natural ecosystems. Recent efforts to lower nitrogen oxides emissions have substantially decreased nitrate wet deposition. Levels of wet ammonium deposition, by contrast, have increased in many regions. Together these changes have altered the balance between oxidized and reduced nitrogen deposition. Across most of the United States, wet deposition has transitioned from being nitrate-dominated in the 1980s to ammonium-dominated in recent years. Ammonia has historically not been routinely measured because there are no specific regulatory requirements for its measurement. Recent expansion in ammonia observations, however, along with ongoing measurements of nitric acid and fine particle ammonium and nitrate, permit new insight into the balance of oxidized and reduced nitrogen in the total (wet + dry) US nitrogen deposition budget. Observations from 37 sites reveal that reduced nitrogen contributes, on average, ∼65% of the total inorganic nitrogen deposition budget. Dry deposition of ammonia plays an especially key role in nitrogen deposition, contributing from 19% to 65% in different regions. Future progress toward reducing US nitrogen deposition will be increasingly difficult without a reduction in ammonia emissions.

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3. Making the first American West

The American West: A Very Short Introduction ◽

10.1093/actrade/9780199858934.003.0004 ◽

2014 ◽

pp. 31-45

Author(s):

Stephen Aron

Keyword(s):

United States ◽

British Empire ◽

American West ◽

Appalachian Mountains ◽

The United States ◽

War Of 1812 ◽

Before And After ◽

Louisiana Purchase ◽

Vast Territory ◽

The Revolution

‘Making the first American West’ outlines the “First West”, a vast territory beyond the Appalachian Mountains that remained the focus of intense rivalries between French, Spanish, and British empire-builders in the decades before and after the Revolution. Their expansionist schemes were entangled with the counter-colonial aspirations and determined occupations of diverse Indian inhabitants. In the wake of the Louisiana Purchase, which gave the United States a farther West, and the War of 1812, which brought a further withdrawal of imperial rivals, Indians' options narrowed. By the 1820s, the inclusive relations that had characterized the lands between the Appalachians and the Mississippi had largely given way to exclusive American occupations.

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Diversity of Gyroporus (Gyroporaceae, Boletales): rpb2 phylogeny and three new species

Phytotaxa ◽

10.11646/phytotaxa.434.3.2 ◽

2020 ◽

Vol 434 (3) ◽

pp. 208-218

Author(s):

NAVEED DAVOODIAN ◽

KENTARO HOSAKA ◽

OLIVIER RASPÉ ◽

OLIVIA A. ASHER ◽

ALAN R. FRANCK ◽

...

Keyword(s):

United States ◽

New Species ◽

Southern Hemisphere ◽

Great Plains ◽

Appalachian Mountains ◽

Distinct Species ◽

The United States ◽

Northeastern United States ◽

Three New Species ◽

Landscape Trees

Three new species of Gyroporus, one from the southern hemisphere (Gyroporus madagascariensis sp. nov.) and two from the northern hemisphere (Gyroporus borealis sp. nov. and Gyroporus smithii sp. nov.), are described. G. madagascariensis is a brownish bolete currently known from Madagascar; it has a mottled pileus somewhat reminiscent of G. mcnabbii, another species known from the southern hemisphere. G. borealis is known from the northeastern United States and is also recorded from the northwestern United States under planted landscape trees. G. smithii corresponds to an orange-colored species that has often been encountered in the United States west and south of the Appalachian Mountains (east of the Great Plains) and is likely often mistaken for G. borealis, which can display orange coloration. Additionally, this study presents evidence that G. roseialbus Murrill and G. subalbellus Murrill, previously synonymized by Rolf Singer, are in fact distinct species.

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Nitrification in undisturbed mixed hardwoods and manipulated forests in the southern Appalachian Mountains of North Carolina, U.S.A.

Canadian Journal of Forest Research ◽

10.1139/x89-187 ◽

1989 ◽

Vol 19 (10) ◽

pp. 1226-1234 ◽

Cited By ~ 6

Author(s):

F. Montagnini ◽

B. L. Haines ◽

W. T. Swank ◽

J. B. Waide

Keyword(s):

United States ◽

North Carolina ◽

Black Locust ◽

Vegetation Type ◽

Appalachian Mountains ◽

The United States ◽

Ammonium Nitrogen ◽

Southern Appalachian Mountains ◽

Clear Cut ◽

Southern Appalachian

This paper summarizes data on nitrification at the Coweeta Hydrologic Laboratory, in the southern Appalachian Mountains of North Carolina, U.S.A., focusing on effects of watershed treatment and vegetation type. At Coweeta, as at other United States sites, oak–hickory forests gave the lowest nitrification potentials. Nitrification potentials and nitrifier numbers were lower in oak–hickory forests of undisturbed watersheds than in disturbed watersheds. Nitrification potentials were also low in a white pine plantation, although higher than in other pine forests in the United States. In a regenerating clear-cut and in a 17-year-old successional forest at Coweeta, nitrification potential was higher in dense stands of black locust (Robiniapseudoacacia L.) than in areas where black locust was absent. In the undisturbed forests at Coweeta, low nutrient availability probably limits the size of nitrifier populations; the influence of soil pH on nitrification was unclear. In the disturbed forests, nitrification is apparently controlled by the availability of ammonium nitrogen and other nutrients.

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Projections of atmospheric mercury levels and their effect on air quality in the United States

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-783-2014 ◽

2014 ◽

Vol 14 (2) ◽

pp. 783-795 ◽

Cited By ~ 5

Author(s):

H. Lei ◽

D. J. Wuebbles ◽

X.-Z. Liang ◽

Z. Tao ◽

S. Olsen ◽

...

Keyword(s):

Climate Change ◽

United States ◽

Climate Warming ◽

Wet Deposition ◽

Global Climate ◽

The United States ◽

Atmospheric Mercury ◽

Western Us ◽

Natural Emissions ◽

Ipcc Sres

Abstract. The individual and combined effects of global climate change and emissions changes from 2000 to 2050 on atmospheric mercury levels in the United States are investigated by using the global climate-chemistry model, CAM-Chem, coupled with a mercury chemistry-physics mechanism (CAM-Chem/Hg). Three future pathways from the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) are considered, with the A1FI, A1B and B1 scenarios representing the upper, middle and lower bounds of potential climate warming, respectively. The anthropogenic and biomass burning emissions of mercury are projected from the energy use assumptions in the IPCC SRES report. Natural emissions from both land and ocean sources are projected by using dynamic schemes. TGM concentration increases are greater in the low latitudes than they are in the high latitudes, indicative of a larger meridional gradient than in the present day. In the A1FI scenario, TGM concentrations in 2050 are projected to increase by 2.1–4.0 ng m−3 for the eastern US and 1.4–3.0 ng m−3 for the western US. This spatial difference corresponds to potential increases in wet deposition of 10–14 μg m−2 for the eastern US and 2–4 μg m−2 for the western US. The increase in Hg(II) emissions tends to enhance wet deposition and hence increase the risk of higher mercury entering the hydrological cycle and ecosystem. In the B1 scenario, mercury concentrations in 2050 are similar to present level concentrations; this finding indicates that the domestic reduction in mercury emissions is essentially counteracted by the effects of climate warming and emissions increases in other regions. The sensitivity analyses show that changes in anthropogenic emissions contribute 32–53% of projected changes in mercury air concentration, while the independent contribution by climate change and its induced natural emissions change accounts for 47–68%.

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