Atmospheric Composition & Air Quality (MAQ-34806) Lecturers: Maarten Krol Wouter Peters

Last week We saw the photochemistry of the troposhere NOx-HOx cycle, role of VOCs, P(O 3 ) We saw the photochemistry of the stratosphere Chapman (O+O 3 ) + catalytic cycles of HO x, NO x, ClO x,... We learned what controls the production or destruction of ozone in the troposphere

This week We will study the many forms and effects of nitrogen (N) in our atmosphere We will perform measurements of NO 2 We will interpret them in a practical

N-cycle: reactive vs. non-reactive Forms of N r : NH 3 /NH 4 + NO 3 -, HNO 3 NO, NO 2, … orgN (e.g. amino-acids)

N-cycle

Efficiency of fertilizer N 100 Fertilizer N

N-cycle Efficiency of fertilizer N 100 Fertilizer N 14 Consumed N

N-cycle Efficiency of fertilizer N 100 Fertilizer N 14 Consumed N 94 Effective N -6

N-cycle Efficiency of fertilizer N 100 Fertilizer N 14 Consumed N 9447 Effective N Plant N -6-47

N-cycle Efficiency of fertilizer N 100 Fertilizer N 14 Consumed N Effective N Plant N Yielded N

N-cycle Efficiency of fertilizer N 100 Fertilizer N 14 Consumed N Effective N Plant N Yielded N Food N

N-cycle Efficiency of fertilizer N 100 Fertilizer N 14 Consumed N Effective N Plant N Yielded N Food N % of the produced reactive Nitrogen is consumed… ……if you are vegetarian!

N-cycle Efficiency of fertilizer N 100 Fertilizer N 4 Consumed N Effective N Plant N Food N Meat N % of the produced reactive Nitrogen is consumed… ……if you eat the vegetarian!

N-cycle Intensive agriculture Industrialisation Historic development Closed cycles of nutrients Labour and Transport

N-cycle Jaar World population and Agricultural area Fertilizer and NOx World population (10^6) Agricultural area 10^6 ha Fertiliser Tg NOx emission N= Food; Energy = N Carl Bosch Fritz Haber

Nitrification and de-nitrification

: Scandinavia, Scotland, US dying off of fish, lakes very blue but little fish population. 1980: Reports of damage to forests in Germany, Scandinavia, Canada, Netherlands, Czecho-Slowakia, Poland. 1985: Effects of eutrophication, too much nitrogen deposition, too much nitrate in drinking water, loss of species in ecosystems, algae blooms Acid deposition A short history of acidification:t

99 Robert Angus Smith ( ) Introduced term: Acid Rain Old English painting nineteenth century Wet deposition and Precipitation chemistry

17 pH Pure water H 2 O ↔ H + + OH dissolved CO 2 CO 2 (g) + H 2 O ↔ H 2 CO 3 * H 2 CO 3 * ↔ HCO H + HCO 3 - ↔ CO H dissolved other natural acids HNO 3 (NO x, lightning, soils, and fires) H 2 SO 4 (sulfur gases, volcanoes and biosphere) Cl - (ocean) Formaldehyde [HCHO] Organic acids: formic acid, acetic acid (biosphere) cations NH 4 + (natural, agriculture) (NH 3 base in rainwater) Ca 2+, Mg 2+, K +, Na + (wind blow) Acid rain: pH < 5 The pH of precipitation

18 The pH-values in atmospheric water of various types Why so low? (lower than pH rain)

The pH of rain water (13.1)

But NH 3 is a base? What now acid rain? ➡ In soils by bacteria: ➡ NH H 2 O + 2O 2 --> NO H 2 O + 2 H + (nitrification) ➡ but also: fertilization (NO 3 2- ) ➡ over-fertilization: eutrophication

NH 3 Sources: Mainly agriculture (94%) FertilizerLiquid manureAnimal house

European NH 3 emissions

Global sources of NH 3 in the troposphere Source, Tg N yr -1 Anthropogenic Biomass burning2 Fertilizers6 Domestic animals22 Subtotal30 Natural Soils and vegetation5 Oceans7 Wild animals2.5 Subtotal14.5 Rodhe et al. (1995)

NO x Envisat picture of NO 2 column Main sources; Traffic 60 % Power plants 12% Industry 15%

Global NOx emissions

European NO x emissions

Current sources of NO x in the troposphere Source, Tg N yr -1 Anthropogenic Fossil fuel combustion21 Biomass burning12 Aircraft0.5 Subtotal33.5 Natural Soils6 Lightning3 NH 3 oxidation3 Transport from stratosphere0.1 Subtotal12.1 (1) Dignon et al.,1991;(2) Atherton et al.,1991;(3) Hameed and Dignon,1992;(4) Dignon and Penner, 1991

What goes up, must come down: global N deposition: mg N m -2 yr -1 Millennium assessment Growth mainly through increased energy use and more intense agriculture

Sensitivity of EU soils for Acid Sensitivity of European soils. 5 classes are used, from white (very insensitive), over light yellow, dark yellow and light red to dark red (very sensitive)

Critical loads for Europe, acidification eutrophication Translation of sensitivity to acid deposition and eutrophication in critical loads in moles per hectare per year

Potential acid deposition in Europe in moles per ha per year F (potential acid) = 2F (SOx) + F (NOy) + F (NHx) F = Load F (SOx) = F (sulfate) + F (SO2) F (Noy ) = sum fluxes of HNO 3 and NO x F (NHx) = sum fluxes NH 3 and NH 4 Correction for base cations: F (corrected pot. acid) = 2F (SOx) +F (NOy) + F (NHx) - F (base cations)

Exceedence of critical loads in moles per ha per year Exceedence in southern Scandinavia because of sensitive soil Exceedence in middle Europe because of high load No exceedence in South Europe because of insensitive soil

The Dutch situation for Acid

The Dutch situation for Nitrogen

Wrap-Up Reactive Nitrogen is central to many environmental issues The use of fertilizer, meat production, and the burning of fossil fuels are the main sources The lifetime of N r is relatively short, so the effects are strongly regional