环境科学与工程英文版教材.doc

Acid Deposition Research in NetherlandsPeking University Shenzhen Graduate SchoolLishui Road Nanshan District Shenzhen Guangdong Province, ChinaAbstract: The EMEP model is applied to simulate the atmospheric transport and deposition of acid pollutants in Europes atmosphere with a 5050 km2 horizontal resolution. The model evaluations for the past twenty years indicate that rather serious exceedances are found for the South and East of the Netherlands. Netherlands have exceeded the limits of acid deposition as regulated by the European Commission in the Goteborg Protocol. The European Commission requires that thsituation is remedied within 2 years. Large fractions of nitrogen oxide(s)(NOx ) and sulfur dioxide(SO2 ) emitted in the Netherlands , are deposited in their neighbouring countries. So reduction of these compounds would not influence acid deposition in The Netherlands very much. As to ammonia, a large portion is deposited within the Netherlands. Hence it is concluded that only ammonia(NH3) reductions can be effective to reach the European air quality standards within the period. Compared to other sources, agriculture is the main source of ammonia. So some proposed measures are necessary to reduce the ammonia production of agriculture, specially of the stock-raising. The feasible way is to develop the eco-ariculture and ,reuse the waste of livestocks. Keyword: EMEP model, Acid Deposition, Exceedance, Reductions1. IntroductionAlthough the nitrogen deposition in the Netherlands(NL) has slightly been reduced the last few years, and the acidifying deposition of sulphur has decreased sharply the last few years, The Netherlands still has a relatively serious acidification problem compared to other European Countries. Both the reductions of the nitrogen oxides and sulphur dioxide do not reach the the standards of acid deposition as regulated by the European Commission. Ammonia which contributes considerably to the potential acid deposition in the Netherlands increased a bit in the last 20 years. Direct harmful effects on vegetation caused by high concentrations of nitrogen and sulphur compounds in air no longer occur at current levels. However, deposition of these compoundsin nature areas leads to acidification and eutrophication. Using EMEP model, it is estimated how many moles of nitrogen and sulphur compounds are emitted and deposited in most European countries. Nitrate oxides, sulphur dioxide and ammonia emissions are calculated with 5050 grid while deposition with 1010. The relation betweenWith these calculations, the sum of emissions and with depositionreceptions in Netherlands is usedcompared to show how to solve the acid deposition problems inwith coordination with the otherof each countries. On the basis of the calculations of the emission/receptor relations it is showned how the acid deposition problems can be solved in an efficient way. 2. Method and analysis of the Regional air pollution situationThe main objective of EMEP is to provide the parties to the convention with information on emissions, transport, concentrations and depositions of air pollutants in Europe. It was set up in 1977 for monitoring and evaluation of the long-range transmission of air pollutants. The EMEP model is used to evaluate the emissions and receptions in Europe with per 5050 km or 1010 km a grid on the map. With the data from each monitor stations, all emission and receptions for each grid are summed up. The pollutants of all grids in Netherlands count up to the emissions of Dutch.(?)(sentence can be omitted, I believe.2.1. The Monitoring method Three main processes for deposition can be distinguished for monitoring which are wet deposition , occult deposion and dry deposion. The wWet deposion isare transported to the surface by means of precipitation, rain or snow in the main process for background area. It includes two processes which are cloud scavenging processes(Rainout) and below cloud scavenging processes(Washout). The rainout process and is by far the most important pathway for wet deposition fluxes. The washout processes are responsible for some 10 to 15% of the wet deposition fluxes. The dDry deposition includes deposition of aerosol particles and gases directly on vegetation and soil without prior uptake in the water phase. And the dry deposition flux is product of vertical deposition velocity (Vd) and ambient concentration(Cx). By measuring the Vd and Cx, the dry deposition flux can be calculated.On each monitoring station, both wet deposition and dry deposition are measured exactly not true, the basis is thye model, not monitoring by stations. That is used to validate = check truth, of model. The occult deposition is only important where much fog is. So it is not mentioned in the research. By sum the wet deposition and dry deposition in each monitoring point, the grid EMEP model is drew. Figure2 shows how the grid map is made up.Grid 50 x 50Land useemissionsMeteorological dataU, T, Rh etc. Model concentration fieldsDescription effects & policyGrid 10 x 10 Land use Meteo, U, T, Model VdModel dry dep Vd x CAdd wet depositionFigure2 EMEP grid model (sjaak slanina, 2001)Using the EMEP model，the grid maps for the exceedence of the critical loads in Europe are calculated. Figure 3 gives the critical loads in the European countries. From the grid with different colors, It is concluded that the south and east of Netherlands are abovebeyond the 700 eqha-1a-1 limits.Figure3. Critical loads for Europe, acidification 2.2 Analysis of acid deposition data Listed in Table 1, Table 2 and Table 3 are the data of import and export of acidifying pollutants for Europe, the results are calculated by EMEP model and given in these tables as transport matrix for SO2, NOx and NHx in Europe. These tables provide data on import and export of SO2, NOx and NHx for the different countries in Europe. In the table, the row indicated as NL gives this information. Lets take an example. In the first half of the table it is indicated (see cross of row NL and column NL that 140 times 100 tons (= 14000 tons) of deposited SOx is caused by the sulfur emissions from The Netherlands itself. The contributions of Belgium, France and Germany (see columns Be, Fr and De) are respectively 9700, 5800 and 4200 tons.(see Table 1).Table 1 Transport matrix SOx in EuropeTable 2 Transport matrix NOx in EuropeTable 3 Transport matrix NHx in Europeupper column means lower column 3. Result The results of analysis of acid deposition in this chapter is givencarried out by datd in the Table 1, Table 2 and Table 3. The origins of acidifying depositions in the Netherlands are given in table 4 and 5. The total deposition amount is shown in Table 4, the forecasted emissions of the Netherlands for the year 2000 are shown in Table 5.Table 4 Origins of acidifying depositions in the Netherlands.SO2NOxNHxTotal acidTotal Netherlands and foreign (%)202060100Countries100 tonsNetherlands140142582864Belgium9746143286France584732137Germany4257115214 European Union4743828901746Uk +Ireland1197913211Other countries1421057254Sum 5984768921966Total foreign (%)77703556Total Netherlands (%)23306544 Table 5 the estimated emissions of the Netherlands for the year 2000SO2NOxNHxTotal potential acid%Target sectorsAgriculture and horticulture0.00.241.141.3Manufacturing industry1.00.50.11.6Refineries1.50.20.01.6Energy supply0.50.40.00.9Traffic and transport2.16.30.08.3Consumers0.00.32.6.2.9Other0.20.30.20.6Total Netherlands 5.38.043.957.2Source: RIVM 2001More than 40% of acid deposition originates in other countries, according to calculations made on the basis of EMAP data. Emissions for the year 2000 have been estimated. A large portion of the NOx, emitted in the NL is exporected to other countries, and will not be deposited in the Netherlands. The same situation exists for SO2 . Comparing the data of SO2 , NOx and NHx , we can find that the ammonia emissions are the main problem in the Netherlands , 2/3 of emitted ammonia is deposited within the Dutch borders. Over 40% of the average acid deposition in the Netherlands comes from ammonia emissions from Dutch agriculture. The Traffic and transport target sector contributes over 8% to acid deposition, with the other sectors contributing less than 3% each.4. Assessments, Measures, and ProposalsesTo reduce the emissions in Netherlands, a lot of measures must be taken. As most of the sulphur dioxides and nitrate oxides are emitted in other countries, controling the emissions only in the Netherlands will not have the desired effect. It depends more on the coordination with the neighborhood. But the most of the ammonia deposited in The Netherlands are emitted by itself. And the largest part is emitted by agriculture. So to solve the problem, the Dutch must control the emission of agriculture . The agricultural area amounts to two million hectares and in 1999, there were 103,000 farms altogether. The enterprises of the farms in Netherlands concentrate on cattle (56 %), horticulture (21 %) and other typessorts of farms(23%). Cattle production igenerates the main source of ammonia . It is effective and helpful to look at some similar cases in other countries. Take Japan as an example A The dairy farm in Hokkaido . They uses a biogas utilized fuel cell co-generation system to deal with the waste. The organic waste ofsuch as livestock waste and corns produces biogas by waythrough high-speed fermentation. Then electricity made by the biogas plant transports to the fuel cell generator. This Efficient fermentation system reduceshas not only excellent energy demandsaving, but also reduce the production of ammonia which the waste stocks generates. Netherlands should follow have the similarity as thethe example of Hokkaido does. There are thousands of farms in Netherlands, which produce more ammonia than the hat of Hokkaido farm. The DutchHolland governments may use the co-generation 3R (Reduce,Recycle and Reuse) system to deal with the waste produced by the livestocks. Although Netherlands have a long way to go in order to reach the standards of acid deposition as regulated by the European Commission in the Goteborg Protocol, these measures may help to reachaccess the goal.5. Conclusions The European Commission has indicated that The Netherlands will be fined with up to of 2 billion Euro, if the limit is not reached in 2006. NOx, SO2, and ammonia contribute to acid deposition in The Netherlands, for respectively, 20, 20 and 60 %. Reduction is required of 500 to 1000 moles per hectare per year, on a level of 3000 moles.ha-1.yr-1. In view of the general practice in Europe, a reduction of 700 moles per ha per year seems very reasonable to meet the demands of the Commission.At moment about 10% of the nature areas are sustainably protected against acidification and eutrophication. It is estimated that the deposition of nitrogen and acidifying substances will both still be on average 0-20% above the deposition targets. Because about 45% of the potential acid deposition and 35% of the nitrogen deposition originate outside the Netherlands, this will be highly dependent on emission reductions in the surrounding countries.A large portion (2/3) of the NOx, emitted in the Netherlands is exported to other countries, and will not be deposited in The Netherlands. The same situation exists for SO2. But 2/3 of the emitted ammonia is deposited within the Dutch borders. Hence it is concluded that only ammonia reductions can be effective to reach the European air quality standards within the period of 2 years.Foreign examples, such as closed cycle farming in Japan, can indicate how the necessary reduction can be obtained. Netherlands may take the same se measures to reach the standards. ReferencesRIVM - Netherlands Environmental Assessment Agency. 2003. The Netherlands contribution to the EMEP air quality assessment report. Acidification and air quality in the past decades and policy targets for 2010. Adopted from the Netherlands Environmental