The largest sources of emissions of nitrogen oxides (NOx) are road transport followed by other mobile sources and combustion in energy industries (mainly public power and district heating plants). The transport sector is the sector contributing the most to the emission of NOx, and the main transport sources are road transport, national navigation, railways and civil aviation. In addition, emissions from national fishing and off-road vehicles contribute significantly to the NOx emission. For non-industrial combustion plants, the main sources are combustion of gas oil, natural gas and wood in residential plants. The emissions from energy industries have decreased significantly since 1990, and in the same though less pronounced trend is seen for the total NOx emission. The reduction is due to the increasing use of catalyst cars and installation of low-NOx burners and denitrifying units in power plants and district heating plants.
The emissions of Non-Methane Volatile Organic Compounds (NMVOC) originate from many different sources and can be divided into two main groups: incomplete combustion and evaporation. Small combustion plants (e.g. residential wood burning) is a big source of NMVOC originating from combustion. Other sources are road vehicles and other transport sources such as national navigation vessels. NMVOC from road transportation vehicles have been decreasing since 1990, due to the introduction of catalyst cars. The evaporative emissions mainly originate from the agricultural sector, use of solvents, and the extraction, handling and storage of oil and natural gas. The total anthropogenic emissions have decreased since 1990, largely due to the increased use of catalyst cars and reduced emissions from use of solvents.
The main part of the sulphur dioxide (SO2) emission originates from combustion of fossil fuels, i.e. mainly coal and oil, in public power and district heating plants. The total SO2 emission has decreased since 1990, mainly due to installation of desulphurisation plant and use of fuels with lower content of sulphur in public power and district heating plants. Despite the large reduction of the SO2 emissions, these plants are still an important emission source, as they account for a large part of the national fuel consumption. In addition, emissions from industrial combustion plants, non-industrial combustion plants and other mobile sources are important.
Almost all atmospheric emissions of ammonia (NH3) result from agricultural activities. Only a minor part of the total emission originates from stationary combustion, road transport, industrial processes and waste. The share for road transport was increasing during the 1990’s and early 2000’s due to increasing use of catalyst cars. In recent years, the share has been decreasing due to more advanced catalysts being implemented.
The major part of the emission from agriculture stems from livestock manure and the largest losses of ammonia occur during the handling of the manure in animal housing systems. The second largest source is agricultural soils, mainly due to emissions from application of mineral fertiliser, application of animal manure and emissions from crowing crops. The total ammonia emission has decreased since 1990.
Due to the action plans for the aquatic environment and the Ammonia Action Plan, a series of measures to prevent loss of nitrogen in agricultural production has been initiated. The measures have included demands for improved utilisation of nitrogen in livestock manure, a ban against field application of livestock manure in winter, prohibition of broadspreading of manure, requirements for establishment of catch crops, regulation of the number of livestock per hectare and a ceiling for the supply of nitrogen to crops. As a result, despite an increase in the production of pigs and poultry, the ammonia emission has been reduced considerably.
The inventory includes the total emission of particles TSP (Total Suspended Particles), emission of particles smaller than 10 µm (PM10) and emission of particles smaller than 2.5 µm (PM2.5).
The largest PM2.5 emission source is residential combustion plants, followed by the transport sector. Emissions from residential plants have increased from 1990 to 2007, followed by a decrease since 2007. The increase was caused by increasing wood consumption while the decrease has been caused by legislative demands on new wood stoves and boilers combined with a slightly lower wood consumption.
For the road transport sector, exhaust emissions account for barely half of the emissions, while the remaining emissions come from tyre and brake wear and from road abrasion. For other mobile sources, the most important sources are off-road vehicles and machinery in the industrial sector and in the agricultural/forestry sector. The PM2.5 emission has decreased since 1990, as the increasing wood consumption in the residential sector has been counterbalanced by decreasing emissions for the remaining sectors, the most important being the transport sector.
The largest TSP emission sources are agriculture and non-industrial combustion. Residential plants is the largest source in the non-industrial combustion sector. The TSP emissions from transport are also important and include both exhaust emissions and the non-exhaust emissions, of which the latter is the dominant source.
The largest BC emission source is residential combustion plants, followed by road transport. Emissions from residential plants have decreased since 1990mainly due to a decreasing trend for the wood consumption.
In the years 1994-2007, the largest emission source was the transport sector. Emission from road transport are almost entirely from exhaust emissions, while emissions from tyre and brake wear are insignificant. Machinery in agriculture and forestry was a large source in 1990, but due to a decreasing trend over the timeseries, this is no longer a dominant BC emission source.
Non-industrial combustion plants are the main source to the total CO emission. For the non-industrial sector, emissions from commercial/institutional sources have increased and emissions from agriculture/forestry/fishing sources have decreased since 1990. In the same period, emissions from the residential sector have been fluctuating around an overall rather constant level. The transport sector is the second largest contributor to the total CO emission, and have been showing a large decrease since 1990. The major transport source is passenger cars, which was the largest transport source in 1990, but has decreased over the years. The main driver is the increase of catalyst cars. In 1990, a law forbidding the burning of agricultural crop residues on fields was implemented, which caused a significant reduction in CO emission. The total CO emission decrease since 1990 is mainly due to decreasing emissions from road transport.
The main lead (Pb) emission sources are transport, waste, non-industrial combustion and industrial processes. In earlier years combustion of leaded gasoline was the major contributor to Pb emissions to air but the shift toward use of unleaded gasoline for transport have decreased the Pb emission from transport significantly. The trend in the Pb emission from non-industrial combustion is decreasing over the time series. In the non-industrial combustion sector, the dominant source is wood combustion in residential plants, which has been increasing since 1990, but counterbalanced by decreasing emissions from stationary combustion in commercial/institutional and in agriculture/forestry/fishing. The decreasing emission from energy industries is caused by the deceasing coal combustion and more efficient particle abatement.
The main sources of emissions of cadmium (Cd) to air are mainly combustion of wood, wood waste and municipal waste. Non-industrial combustion is the largest source, and the main part of the emission comes from residential plants. Emissions from residential plants have shown a large increase since 1990 due to increasing wood consumption, but counteracted by emission reduction due to legislation for new wood stoves and boilers. Emissions from energy industries, manufacturing industries and construction, and industrial processes have also shown a large decrease since 1990. The decreasing emission from energy industries are related to the decreasing combustion of coal.
The largest sources of mercury (Hg) emissions are waste incineration and coal combustion in energy industries. Due to improved flue gas cleaning and decreasing coal combustion the emissions from Energy industries decreased significantly in the period 1990-2000. The trend has continued though with a less pronounced decrease since 2000. Non-industrial combustion is dominated by wood combustion in residential plants, while the main contributions to emissions from manufacturing industries and construction are food processing, beverages and tobacco, and non-metallic minerals. The variations in emissions from industrial processes owe to the closure in 2002 followed by re-opening and a second shut down in 2005 of the only Danish electro-steelwork.
In 1990, the largest sources of arsenic (As) emissions was coal combustion in energy industries. Due to improved flue gas cleaning and decreasing coal combustion the emissions from Energy industries decreased significantly in the period 1990-2006. The trend has continued, though with a less pronounced decrease, since 2006. In recent years, emissions from the main sectors energy industries, manufacturing industries and construction, transport non-industrial combustion, and industrial processes and product use are on the same level. Emissions from energy industries fluctuates according to the coal consumption, and is the largest source in years with relatively large electricity export.
The largest sources of chromium (Cr) emissions is coal combustion in energy industries. Due to improved flue gas cleaning and decreasing coal combustion the emissions from Energy industries decreased significantly in the period 1990-2000. The trend has continued though with a less pronounced decrease since 2000. Non-industrial combustion is dominated by wood combustion in residential plants. Emissions from residential plants have shown a large increase since 1990 due to increasing wood consumption, but counteracted by emission reduction due to legislation for new wood stoves and boilers. The large decrease of emissions from energy industries has caused non-industrial combustion to be the largest sector since 2000.
Automobile tyre and brake wear is by far the major emission source to copper (Cu) emissions for all years in the time series. The second largest source is emissions from use of fireworks, which has been increasing since 1990. In the first part of the time series public electricity and heat production contributed as the second largest source, but due to decreasing emissions from this sector and increasing emissions from use of fireworks, the contribution is in the recent years very limited.
The largest sources of nickel (Ni) emissions is coal combustion in energy industries. Due to improved flue gas cleaning and decreasing coal combustion the emissions from Energy industries decreased significantly in the period 1990-2000. The trend has continued though with a less pronounced decrease since 2000. Manufacturing industries and construction also make a significant contribution, but has shown a rather constant decreasing trend since 1990. Emissions from the transport sector has been fluctuating around the same level since 1990. Due to the decreasing emissions from energy industries and to a less degree from manufacturing industries and construction, the transport sector has the largest emission contribution in the later years.
The largest sources of selenium (Se) emissions is coal combustion in energy industries. Due to improved flue gas cleaning and decreasing coal combustion the emissions from Energy industries decreased significantly since 1990. Despite the significant decrease, energy industries is still the major source to Se emissions.
Zinc (Zn) emissions mainly come from the transport sector, and the emissions have shown an increasing trend since 1990. Road transport is the largest source, and emissions from non-exhaust (tyre and brake wear) exceeds the emissions from exhaust. Energy industries contribute significantly in the early years of the time series, but has decreased especially from 1990 to 2000. Emissions from non-industrial combustion has increased especially in the years 2000-2007, and has following become a major source. The main part of the emission comes from residential plants, which has shown an increase since 1990 due to increasing wood consumption, but counteracted by emission reduction due to legislation for new wood stoves and boilers. Emissions from the waste sector has been on a relatively constant level since 1990. The major source is accidental fires, mainly vehicle fires.
The emission inventory for polycyclic aromatic hydrocarbons (PAH) includes four PAHs: benzo(a)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene and indeno(1,2,3-cd)pyrene. The major part of the total PAH emission is benzo(b)fluoranthene and benzo(a)pyrene.
PAHs occur in two forms; as gas and adsorbed on particles. PAHs are toxic compounds and especially particulate PAHs are potentially carcinogenic. Benzo(a)pyren (BaP) was one of the first known carcinogen compound. It is the best examined and one of the most toxic PAHs classified as “probably carcinogenic to humans” according to the IARC classification. It is not possible to find a lower concentration limit under which PAHs are not associated with a health risk. For further information in PAHs please refer to the book “Tjærestoffer” (in Danish).
The most important source of PAHs emissions is combustion in the residential sector (mostly wood burning). The decreasing emission trend from 1990 is due to decreasing emissions from the residential sector caused by newer technologies with more complete combustion.
The major part of the dioxin emission owes to wood combustion in the residential sector, mainly in wood stoves and ovens without flue gas cleaning. The second largest source is the waste sector, where emissions mainly owe to accidental fires, especially building fires. The emissions of dioxins from energy industries are dominated by emissions from combustion of biomass as wood, wood waste and to a less extend agricultural waste.
Stationary combustion is the major source to emissions of hexachlorobenzene (HCB). This owes mainly to combustion of municipal solid waste in heating and power plants. Transport is another important source. Emissions from transport have increased since 1990 due to increasing diesel consumption. The HCB emission from stationary plants has decreased since 1990 mainly due to improved flue gas cleaning in municipal solid waste incineration plants. The emission from agriculture was very high in the early 1990’ties due to the use of pesticides containing impurities of HCB. The HCB emission from agriculture decreased significantly since 1990. The emission from industrial processes has decreased due to the closure of steel production and secondary aluminium production in Denmark.
Energy industries is the largest source to emissions of polychlorinated biphenyls (PCBs) emission. This owes mainly to combustion of biomass and coal. The emission from energy industries has decreased significantly since 1990 due to the lower fuel consumption, especially of coal. The emission from industrial processes was dominated by the steel production. The plant closed down during 2001 and briefly reopened in 2005.