Air pollution and atmospheric deposition trends in remote areas of North America

Transcription

1 Air pollution and atmospheric deposition trends in remote areas of North America Andrzej Bytnerowicz USDA Forest Service PSW Research Station Riverside, CA, USA Ozone Criteria pollutant Toxic to humans and vegetation Due to aggressive control strategies, peak concentrations have decreased Big potential problem increasing background concentrations due to uncontrolled emissions of precursors in developing countries and long range, intercontinental transport 1

2 Air Trends, EPA, 2

3 Three Year Average of Fourth Highest Daily Maximum 8 Hour Average Ozone Concentrations (ppb) for (CASTNET) Ozone distribution in complex mountain terrain is difficult to model so ground level measurements are needed 3

4 Passive samplers & portable active monitors have been successfully used in remote areas for monitoring various pollutants Passive sampler assembly VOCs NOx NO 2 HNO 3 NH 3 O 3 SO 2 4

5 Western Sierra Nevada has the highest ozone pollution, but high ozone levels are also found in the Owens Valley Lake Tahoe Basin ozone and N deposition study 5

6 High differentiation of ozone diurnal profiles in complex mountain terrain Ozone, sampling period July 14-29, ppbv Watson Creek Genoa 7000 Genoa 8000 Genoa 9000 Angora Blackwood Valhalla Thunderbird Incline Sugar Pine Hour Joshua Tree National Park most polluted US national park 6

7 Joshua Tree NP, s. California, summer 2003 Joshua Tree NP, s. California, spring

8 Joshua Tree NP, ozone concentrations 0.14 Winter minima and maxima 0.12 R² = ppm R² = Year 0.18 Joshua Tree NP, ozone concentrations Summer minima and maxima R² = ppm R² = Year 8

9 Joshua Tree NP, ozone exposure index SUM00 summer R² = ppm h Year Joshua Tree NP, ozone exposure index 160 SUM 60 summer 140 R² = ppm h Year 9

10 Joshua Tree NP, ozone exposure index W 126 summer R² = ppm h Year Forest fires affect air quality 2002 McNally 2003 Old Fire McNally 10

11 Wildfires and ozone Wildfires can significantly increase the frequency of O 3 concentrations exceeding the U.S. health standards, and might cause violations also during photochemically less active seasons (Pfister et al., 2008) Southern California fires O 3 of 2007 caused large increase of O 3 concentrations to ~95 ppb (~40 ppb higher than during the pre fires conditions) (Bytnerowicz et al., 2010). Influence of Fires on O 3 Concentrations in the Western U.S (Jaffe et al., Environ. Sci. Technol. 2008, 42, ). 11

12 Wildfires are also important source of other air pollutants Gaseous pollutants: CO, CO 2, NH 3,NO, NO 2, HNO 3, VOCs Particulate pollutants (inorganic, including heavy metals; various organic compounds, including many carcinogens) Other criteria pollutants SO 2 NO 2 Lead Particulate matter 12

13 2009 SO

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15 2009 Gaseous nitric acid

16 2009 Particulate NO Particulate NH

17 2009 Particulate SO Ammonia pollutant of an increasing importance Emissions do not decrease in contrast to oxidized forms of N and are not regulated Ammonia has a high deposition velocity and high contribution to dry N deposition At elevated levels NH 3 may be toxic (sensitive plants, lichens) 17

18 Ammonia in the Athabasca Oil Sands Region, Alberta, Canada 18

19 Monitoring network Ammonia concentrations have been elevated during the entire monitoring period B205 B210 B213 B213 V.G..5m B213 V.G. 1m B213 V.G. 2m AH3 AH7 AH8-R JP212 PH2 PH4 PL1 PL7 Stn#1 Stn#2 Stn#4 Stn#5 Stn#6 Stn#7 Stn#9 Stn#10 Stn#10T Stn#11 Stn#12 Stn#13 Stn#14 Stn#15 Lysimeter Peat Pond W1DUMP BM10 BM11 BM7 NE10 NE11 NE7 SM7 SM8 WF NH ug/m May05 Jun05 July05 Aug05 Sept05 Oct05 Nov05 Dec05/Jan06 Feb06 Mar06 Apr06 May06 Jun06 Jul06 Aug06 Sep06 Oct06 Nov06 Dec06 Jan07 Feb07 Mar07 Apr07 May07 Jun07 Jul07 Aug07 Sep07 Oct07 Nov07 Dec07 Jan08 Feb08 Mar08 Apr08 May08 Jun08 Jul08 Aug08 Sep08 Oct08 Nov08 Dec08 Month Year 19

20 NH 3 winter 2008/2009 NH 3 summer

21 Among reactive N species in the Athabasca Oil Sand Region, ammonia has the highest potential for significant ecological effects 2.5 HNO3 N NO2 N NH3 N 2.0 Concentration (μg/m3) Winter Summer Sierra Nevada NH 3 concentrations (μg/m 3 ) August 5 18, A Hills A Hills RL RL CED CED CON CON MP MP G C F G C F DEPO DEPO BP BP SCF SCF T Pass T Pass ML ML SNARL SNARL Bishop Bishop W M t W M t IV IV MAN MAN 21

22 Atmospheric deposition Potential negative consequences to terrestrial and aquatic ecosystems of reactive N and S Acidification Eutrophication (nitrogen enrichment) Evaluation of potential effects using Critical Loads methodologies EPA has proposed a new secondary NOx & SOx standard linked to Critical Loads for acidification of water bodies EPA, Reactive N Committee Report, 2009, US sources of reactive N (Tg/year) 22

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25 Apportionment of N deposition, (CASTNET) Monitoring all forms of reactive N allows to understand the origin of deposited N (Lake Tahoe, summer 2010) Inorganic gaseous N apportionment, July 14 29, HNO3 NO NO2 NH3 N (μg/m 3 )

26 Mercury another pollutant of high importance Conclusions Generally, ambient air pollution (SO 2, NOx and O 3 ) as well as atmospheric deposition of N and S in North America show declining trends. Ambient ozone and atmospheric nitrogen deposition have most significant effects on forest ecosystems. Emissions of reduced nitrogen (NH 3 and NH 4+ ) should be regulated in order to be able to control nutritional (eutrophic) effects of excessive N in environment. Future projections of air pollution trends have a high level of uncertainty mainly due the unknown future technologies, global population & economy changes, and many other factors. 26

27 Thank you!!! 27