scholarly journals Decreases in Mercury Wet Deposition over the United States during 2004–2010: Roles of Domestic and Global Background Emission Reductions

Atmosphere ◽  
2013 ◽  
Vol 4 (2) ◽  
pp. 113-131 ◽  
Author(s):  
Yanxu Zhang ◽  
Lyatt Jaeglé
Keyword(s):  
United States ◽  
Wet Deposition ◽  
The United States ◽  
Emission Reductions ◽  
Background Emission ◽  
Global Background

scholarly journals Health benefits of decreases in on-road transportation emissions in the United States from 2008 to 2017

2021 ◽  
Vol 118 (51) ◽  
pp. e2107402118
Author(s):  
Ernani F. Choma ◽  
John S. Evans ◽  
José A. Gómez-Ibáñez ◽  
Qian Di ◽  
Joel D. Schwartz ◽  
...  
Keyword(s):  
United States ◽  
Urban Areas ◽  
Metropolitan Areas ◽  
Health Benefits ◽  
The United States ◽  
Emission Factors ◽  
High Impact ◽  
Attributable Mortality ◽  
Emission Reductions ◽  
Air Pollution Regulation

Decades of air pollution regulation have yielded enormous benefits in the United States, but vehicle emissions remain a climate and public health issue. Studies have quantified the vehicle-related fine particulate matter (PM2.5)-attributable mortality but lack the combination of proper counterfactual scenarios, latest epidemiological evidence, and detailed spatial resolution; all needed to assess the benefits of recent emission reductions. We use this combination to assess PM2.5-attributable health benefits and also assess the climate benefits of on-road emission reductions between 2008 and 2017. We estimate total benefits of $270 (190 to 480) billion in 2017. Vehicle-related PM2.5-attributable deaths decreased from 27,700 in 2008 to 19,800 in 2017; however, had per-mile emission factors remained at 2008 levels, 48,200 deaths would have occurred in 2017. The 74% increase from 27,700 to 48,200 PM2.5-attributable deaths with the same emission factors is due to lower baseline PM2.5 concentrations (+26%), more vehicle miles and fleet composition changes (+22%), higher baseline mortality (+13%), and interactions among these (+12%). Climate benefits were small (3 to 19% of the total). The percent reductions in emissions and PM2.5-attributable deaths were similar despite an opportunity to achieve disproportionately large health benefits by reducing high-impact emissions of passenger light-duty vehicles in urban areas. Increasingly large vehicles and an aging population, increasing mortality, suggest large health benefits in urban areas require more stringent policies. Local policies can be effective because high-impact primary PM2.5 and NH3 emissions disperse little outside metropolitan areas. Complementary national-level policies for NOx are merited because of its substantial impacts—with little spatial variability—and dispersion across states and metropolitan areas.

scholarly journals Model analyses of atmospheric mercury: present air quality and effects of transpacific transport on the United States

2013 ◽  
Vol 13 (4) ◽  
pp. 9849-9893 ◽  
Author(s):  
H. Lei ◽  
X.-Z. Liang ◽  
D. J. Wuebbles ◽  
Z. Tao
Keyword(s):  
United States ◽  
Air Quality ◽  
Wet Deposition ◽  
Total Mercury ◽  
The United States ◽  
Atmospheric Mercury ◽  
Anthropogenic Sources ◽  
Mercury Deposition ◽  
Transpacific Transport ◽  
Mercury Cycle

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.

scholarly journals Monetized health benefits attributable to mobile source emission reductions across the United States in 2025

2019 ◽  
Vol 650 ◽  
pp. 2490-2498 ◽  
Author(s):  
Philip Wolfe ◽  
Kenneth Davidson ◽  
Charles Fulcher ◽  
Neal Fann ◽  
Margaret Zawacki ◽  
...  
Keyword(s):  
United States ◽  
Health Benefits ◽  
The United States ◽  
Mobile Source ◽  
Emission Reductions ◽  
Source Emission

scholarly journals Increasing importance of deposition of reduced nitrogen in the United States

2016 ◽  
Vol 113 (21) ◽  
pp. 5874-5879 ◽  
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.

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

2014 ◽  
Vol 14 (2) ◽  
pp. 783-795 ◽  
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%.

scholarly journals The Copenhagen Climate conference: it still takes two to tango

2010 ◽  
Vol 6 (1) ◽  
Author(s):  
Peter Neilson
Keyword(s):  
Climate Change ◽  
United States ◽  
House Of Representatives ◽  
Developed Countries ◽  
The United States ◽  
Emissions Reduction ◽  
Least Developed Countries ◽  
Emission Reductions ◽  
Dance Floor ◽  
The Us

At Copenhagen most of the countries present had a better offer for emission reductions to table, but it needed the United States and China to go onto the dance floor to really get the party going. The US, while offering to help contribute to $100 billion a year in assistance from 2020 for least developed countries facing the full impact of climate change, did not move beyond an emissions reduction target of 17% below 2005 levels by 2020. This reduction is in the Waxman Markey Bill passed by the House of Representatives in 2009. 

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