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1.
Measurements of wet deposited NH4+, SO42−, NO3 and Cl, as well as airborne concentrations of these species and gaseous HNO3, HCl and NH3, have been made at a site in eastern England. Scavenging ratios based solely upon aerosol-associated species and upon aerosol plus gaseous airborne species are presented and compared with literature values. It appears that HCl and HNO3 have only a rather minor influence upon wet deposition at our site. Gaseous NH3 influences ground-level air chemistry appreciably, but scavenging ratios for NH4+ are low, even when based upon aerosol NH4+ concentrations alone, presumably due to altitudinal gradients in this species. The problems inherent in interpretation of scavenging ratios are discussed. Deposition of nitrogen in various chemical forms is estimated from rainwater and air composition. If a transport-limited deposition velocity is assumed for ammonia gas, dry deposition of this species accounts for around 40% of total nitrogen deposition to the ground.  相似文献   

2.
内蒙古温带草原氮沉降的观测研究   总被引:5,自引:5,他引:5  
张菊  康荣华  赵斌  黄永梅  叶芝祥  段雷 《环境科学》2013,34(9):3552-3556
在内蒙古太仆寺旗对温带草原地区的氮沉降进行了为期1 a(2011年11月~2012年10月)的观测.在线分析大气NH3和NO2浓度,用CMAQ模型计算的干沉降速率计算了气体干沉降量;采集降水、降尘和穿透雨样品并测定NH4+和NO3-浓度,分别得到湿沉降、颗粒物干沉降和穿透雨沉降量.观测结果表明该地区的氮沉降量已经高达3.43 g.(m2.a)-1,有可能对草原生态系统产生危害.其中,湿沉降占44%,气体干沉降占38%,颗粒物干沉降占18%.干沉降对氮沉降的贡献大于湿沉降,必需重视干沉降的测定,而穿透雨沉降明显小于总沉降,说明穿透雨法不适合于草原地区.从组分上看,还原态氮(包括NH4+和NH3)对氮沉降的贡献为71%,而氧化态氮(NO3-和NO2)的贡献仅29%,因此在控制氮沉降时,不应只针对NOx排放进行削减,NH3减排同样重要.  相似文献   

3.
北京市内到郊区氮沉降时空变化特征   总被引:1,自引:0,他引:1  
对北京市区到远郊梯度带上的4个采样点(北京师范大学(BNU)、奥林匹克森林公园(AS)、减河公园(JH)、延庆上辛庄(YQ))降雨和针叶树穿透雨雨量及其化学成分进行了监测,分析了从市中心到远郊的氮沉降时空变化规律.结果表明:梯度带上各点铵态氮(NH+4-N)与硝态氮(NO-3-N)均为5、6月最大,7月开始迅速减小,雨季降雨的稀释作用是主要原因.在空间上,NH+4-N与NO-3-N沉降量大小为BNUJHASYQ,4个样点对应的可溶性无机氮(铵态氮与硝态氮)总沉降量分别为22.6、13.7、12.1、5.42 kg·hm~(-2)a-1(以N计).无机氮沉降以湿沉降为主,4个样点上湿沉降所占比例分别为BNU 72.44%、AS 65.97%、JH 62.78%、YQ 93.86%;沉降成分以铵态氮为主,所占比例分别为BNU56.41%、AS 59.47%、JH 61.21%、YQ 63.33%,从城区到远郊逐次增大.国内外同类研究综合表明,湿沉降中无机氮浓度均是工业区市区郊区远郊区,北京降雨中无机氮浓度相对较高.大多数研究区的城区与郊外大气氮沉降均是以铵态氮为主,与市区交通及生活源氮氧化物排放较高的实际并不一致,其成因与机制尚不明确.  相似文献   

4.
通过分析2000至2014年菲律宾马尼拉(Manila)和洛斯巴诺斯(Los Banos)大气湿沉降资料,初步探讨近15年湿沉降中无机氮含量特征以及对南海东部海域水生生态系统的影响。结果显示,湿沉降中NO-3-N和NH+4-N的浓度均为旱季高雨季低;NO-3-N浓度在近15年虽有波动,但并无明显变化趋势;而洛斯巴诺斯区域的NH+4-N浓度自2009后稍有波动上升。NO-3-N和NH+4-N的沉降通量与浓度相反,表现为雨季高而旱季低,年际上总体表现为NH+4-N的沉降通量大于NO-3-N,马尼拉无机氮的沉降通量大于洛斯巴诺斯,并且在2003年之后,马尼拉和洛斯巴诺斯NH+4-N的沉降通量均呈明显上升趋势,菲律宾经济的快速增长及人类活动是主导其上升的主要因素。马尼拉和洛斯巴诺斯湿沉降中NO-3-N/NH+4-N值分别为0.33和0.41,该比值和无机氮浓度与南海东部各海区表层海水的值有明显的差别,因此降水可能改变该海域表层水体无机氮的组成结构,进而影响水体中浮游植物的生长及其群落结构。  相似文献   

5.
贵州省六冲关流域大气沉降和地表水化学特征   总被引:1,自引:0,他引:1  
对比贵州六冲关森林小流域1992─1994年和2001─2005年2个时期穿透水沉降(TF)和地表水的化学组成,以分析大气沉降对森林小流域生物地球化学过程的影响. 结果表明:2001─2004年硫沉降量较1992─1994年有显著下降,但自2005年起硫沉降量又显著增加. 六冲关流域无机氮(尤其是NH4+-N)沉降量较历史时期显著增加,说明贵阳市大气污染正在由硫酸型向硫酸-硝酸混合型过渡. 长期的大气沉降导致地表水中SO42-和NO3-等阴离子质量浓度的增加,加剧了Ca,Mg和K等营养元素的流失,使地表水的酸中和能力在2002年为负值. 长期观测发现,地表水酸中和能力与穿透水中Ca和Mg的沉降通量密切相关,说明大气沉降已经对六冲关流域的相关生物地球化学过程造成了潜在的影响.   相似文献   

6.
Atmospheric dry deposition to branches of Pinus contorta and P. albicaulis was measured during summer 1987 in a sub-alpine zone at Eastern Brook Lake Watershed (EBLW), eastern Sierra Nevada, California. Results are presented as deposition fluxes of NO3, SO42−, PO43−, Cl, F, NH4+, Ca2+, Mg2+, Na+, K+, Zn2+, Fe3+, Mn2+, Pb2+ and H+, and compared with other locations in California and elsewhere. Deposition fluxes of anions and cations to the pine branches were low, several times lower than the values determined near the Emerald Lake Watershed (ELW), another sub-alpine location in the western Sierra Nevada. The sums of deposition fluxes of the measured cations and anions to pine surfaces were similar, in contrast to the ELW location where the sums of cation fluxes were much higher than the sums of anion fluxes. A strong positive correlation between depositions of NO3 and NH4+, as well as SO42− and Ca2+, suggested that large portions of these ions might have originated from particulate NH4NO3 and CaSO4 deposited on pine surfaces. An estimated total N dry deposition (surface deposition of NO3 and NH4+ and internal uptake of NO2 and HNO3) to the forested area of the EBLW was 29.54 eq ha−1 yr (about 414 g H ha−1 yr−1).  相似文献   

7.
Atmospheric dry deposition of ions to branches of native Pinus contorta and Pinus monticola (natural surfaces), and nylon filters and Whatman paper filters (surrogate surfaces) were measured in the summer of 1987 in the vicinity of Emerald Lake Watershed (ELW) of the Sequoia National Park located on the western slope of the Sierra Nevada in California. Deposition fluxes of airborne NO3, NH+4 and SO2−4 to native pines at the ELW were much higher than in the eastern Sierra Nevada, but several times lower than deposition fluxes to natural and surrogate surfaces at the highly polluted site in the San Gabriel Mountains of southern California. Deposition fluxes of NO3 and NH4+ to the natural and surrogate surfaces at the ELW were much higher than deposition of SO42−, providing the importance of N compounds in atmospheric dry deposition in this part of the western U.S. A deficit of inorganic anions in materials deposited to various surfaces indicated a possibility of substantial participation of organic acids in atmospheric dry deposition processes. Nylon and paper filters proved to be poor surrogate surfaces for the estimation of ionic dry deposition to conifer branches.  相似文献   

8.
A European scale network was established in 2006 as part of the NitroEurope Integrated Project to infer reactive nitrogen (Nr) dry deposition fluxes, based on low-cost sampling of gaseous and aerosol species and inferential modelling. The network provides monthly measurements of NH3, NH4+, HNO3 and NO3, as well as SO2, SO42−, HCl, Cl and base cations at 58 sites. Measurements are made with an established low-cost denuder methodology (DELTA) as a basis to: (1) examine temporal trends and spatial patterns across Europe, (2) improve and calibrate inferential modelling techniques to estimate exchange of Nr species, (3) provide best estimates of atmospheric dry N deposition, and (4) permit an analysis of net GHG exchange in relation to atmospheric and agricultural N inputs at the European scale. Responsibility for measurements is shared among seven European laboratories. An inter-comparison of the DELTA implementation by 6 laboratories at 4 test sites (Montelibretti, Italy; Braunschweig, Germany; Paterna, Spain and Auchencorth, UK) from July to October 2006 provided training for the laboratories and showed that good agreement was achieved in different climatic conditions (87% of laboratory site-means within 20% of the inter-laboratory median). Results obtained from the first year of measurements show substantial spatial variability in atmospheric Nr concentrations, illustrating the major local (NH3) and regional (HNO3, NO3, and NH4+) differences in Nr concentrations. These results provide the basis to develop future estimates of site-based Nr dry deposition fluxes across Europe, and highlight the role of NH3, largely of agricultural origin, which was the largest single constituent and will dominate dry Nr fluxes at most sites.  相似文献   

9.
This paper addresses two hypothesis that try to explain the difference observed between the estimated NH3 emission levels in The Netherlands and those indicated by atmospheric measurements, the so called ‘ammonia gap’: the role of SO2 emissions regulating ambient NH3 concentrations through co-deposition, and long-term NH3 emissions after slurry injection. It was found that throughfall measurements of NH4+ could not be used as indicator for changes in NH3 emissions. The throughfall deposition of NH4+ is in close equilibrium to SO42− and NO3 and is thus regulated by the equilibrium of ambient NH3 and NH4+ in wet deposition and canopy water layers. When SO2 emissions decrease, the amount of available SO42− decreases, which imposes a limit on the deposition of (NH4)2SO4. Long-term emissions of NH3 after application of manure were monitored using a new technique, which continuously measures the concentration of NH3 in a cross-section of the emission plume downwind of the source. The emissions could be registered for 3 weeks after application of manure. The results indicate that the long-term emissions only contribute 1–2% to the total emission level. Both the effect of SO2 on the NH3 deposition levels and the long-term emission fluxes are not enough to explain the observed ammonia gap. It seems that several counteracting effects, some of them emerging from the new emission reduction regulations, contribute to the ammonia gap. An integrated approach to abate ammonia emissions is, therefore, needed. The implementation and regulation of production ceilings for reactive nitrogen might be a good option.  相似文献   

10.
太湖丘陵地区农田氮素迁移的时空分布特征   总被引:8,自引:1,他引:8  
王鹏  高超  姚琪  韩龙喜  申霞 《环境科学》2006,27(8):1671-1675
在太湖丘陵地区选择4种有代表性的土地利用类型进行野外原位试验,研究自然降雨条件下氮素随地表径流迁移的时空分布特征.试验结果表明,随地表径流迁移的农田氮素以氨氮为主,其“次降雨径流平均浓度”中位值占总氮的44.5%,亚硝态氮浓度最小,仅占1.8%.地表径流中的氮素浓度存在显著的季节性差异,其分布主要受降水量、气温等气象条件以及农事活动的影响.总氮、氨氮、硝态氮和亚硝态氮的“多场降雨径流平均浓度”的时间变异性依次减小.菜地径流中总氮、氨氮和硝态氮以及竹林亚硝态氮的SMC值最高,不同土地利用下氮素浓度的空间分布主要与施肥条件以及植被覆盖度有关.各氮素形态SMC值的空间变异性小于其时间变异性.旱地和菜地的氮素迁移通量大于板栗林和竹林,径流量是导致迁移通量存在显著差异的主导因素.  相似文献   

11.
为了研究峨眉山地区降水、云雾水明显酸化的原因,1985年10月我们进行了集中观测,并就其测定结果进行分析研究。  相似文献   

12.
随着我国工业化和城镇化的深入推进,人们对城市大气环境质量关注日益增加。连续五年对山西省太原市5个点位进行监测,考察降水中主要离子时间变异及大气干湿沉降规律。结果表明:太原市五个监测点年均干沉降量排序为太钢工业区坞城(东)桃园(市中)晋祠(景区)上兰(市郊),其中太钢年均沉降量是上兰的三倍。降尘量除了在不同点位差异较大外,相同点上不同季节也有较大波动,表现为各监测点春季和冬季降尘量为全年最高。而夏季由于降雨较多,干沉降最少。总体上,近五年各点干沉降量呈现逐年下降的趋势。湿沉降方面以桃园为市区代表分析,SO_4~(2-)、NO_3~-、Ca~(2+)和NH_4~+是太原市桃园降水中主要的无机离子,其加权平均浓度范围为3.1~19 mg/L,各离子浓度在干燥的冬春季较高,且近五年其浓度及沉降量快速增加。桃园降雨中SO_4~(2-)和NO_3~-仍然是最主要的致酸离子,SO_4~(2-)年均沉降量分别是NO_3~-、Ca~(2+)和NH_4~+的1.7、3.9、5.9倍。Ca~(2+)、NH_4~+和Mg~(2+)的中和因子分别是0.42、0.30、0.14,说明Ca~(2+)、NH_4~+对酸雨缓冲作用大于Mg~(2+)。2013~2017年太原市桃园降雨SO_4~(2-)/NO_3~-和NH_4~+/NO_3~-比值分别为1.7和0.3,表明酸雨类型由硫酸型向混合型发展,主要是近年来NO_3~-浓度增幅大于SO_4~(2-)和NH_4~+。总的来看,近些年太原市政府大力提倡节能减排带来明显效果,但工业厂矿区周边降尘污染依然严重,属于今后城市环境治理的重点。  相似文献   

13.
应用扩散管测量霾污染期间大气氮硫化合物浓度的方法   总被引:4,自引:2,他引:2  
活性氮和硫化合物在大气颗粒物形成过程中扮演重要角色,但对它们气相/颗粒相的同步观测结果比较缺乏.本研究尝试基于扩散管的DELTA系统测量氮和硫化合物短时累积浓度,以期捕捉它们在霾污染期间的演变规律.结果表明,DELTA系统收集气态污染物的扩散管中以及颗粒物滤膜上NH_4~+和NO-3空白干扰较小,适用于研究NH_3、HNO_3、NH_4~+和NO-3的日均浓度,可以作为城市环境空气质量监测参数的有效补充;但采样系统中SO_2-4背景含量较高,仅适合监测48 h以上时间尺度的SO_2浓度和周~月尺度SO_2-4浓度,用于大气硫沉降观测.北京2016年5月9日~6月7日观测期间,大气NH_3、HNO_3、NH_4~+和NO-3浓度具有明显的逐日演变规律,呈现出随着风向转变而发生周期性波动的典型特征;这些含氮污染物与PM_(2.5)、CO、SO_2和NO_2浓度的变化规律一致,其来源可能与化石燃料燃烧源有关.污染天NH_3、HNO_3、NH_4~+和NO-3浓度约为清洁天的2倍,但还原性氮和氧化性氮的相态分布在清洁天和污染天无明显差异;整个观测期间,HNO_3/NO-3约为1.2,NH_3/NH_4~+为4.5,春夏之交较高的温度有利于活性氮在气粒平衡过程中偏向于气态形式存在.  相似文献   

14.
The use of filter packs and a cascade impactor during a series of research cruises in the southern area of the North Sea has yielded detailed spatial distribution patterns of aerosol concentrations, Cl, NO3, SO42−1 and NH4+ and gaseous concentrations, HCl, HNO3 and NH3. The overall distribution of the atmospheric concentrations closely parallels published modelled results for metallic species. The chemical transformations of these aerosols and gases are investigated together with their interactions with the seasalt aerosol. Aerosol chloride loss is greatest in the more polluted areas, whilst concentrations products of NH3 with HNO3 and HCl appear insufficient to sustain the existence of NH4NO3 and NH4Cl. Nitrate is associated predominantly with larger particles and appears to be present substantially as a surface coating on marine aerosol. The total dry deposition input for nitrogen species is calculated for the southern sector with extrapolation to the whole of the North Sea, using particle size weighted deposition velocities of 0.63 and 0.21 cm s−1 for NO3−1 and NH4+, respectively, and literature-derived values for the gaseous constituents. Finally the use of air-mass back trajectories illustrates the role of source regions in influencing the chemical composition of the North Sea atmosphere.  相似文献   

15.
氮沉降已成为河流、湖泊及城市等生态系统的主要污染威胁因素之一,森林生态系统能从林冠、地被和土壤自上而下截留过滤大气降雨中的NH+4-N和NO-3-N,是区域大气环境污染生态防治的重要途径.选取华西雨屏区几种典型人工林森林生态系统为研究对象,采用定位监测与室内分析相结合的研究方法,于2011年4—12月对大气降水、穿透雨、树干茎流、地表径流和地下渗滤NH+4-N和NO-3-N的含量与分配进行了研究.结果表明:观测期内40次降雨总雨量为492.72 mm,NH+4-N和NO-3-N的总沉降量分别为13.248 kg·hm-2和16.320 kg·hm-2;3种人工林林冠层对NH+4-N和NO-3-N的过滤能力表现为香樟林混交林柳杉林,而地表和土壤层均表现为混交林香樟林柳杉林;无林地、香樟林、柳杉林和混交林生态系统无机氮截留过滤净输入量分别为19.557、44.079、42.331、64.896 kg·hm-2,对无机氮的综合过滤作用表现为混交林香樟林柳杉林无林地.这些结果说明华西雨屏区合理配置混交林能更加有效地降低大气氮沉降对生态系统的影响.  相似文献   

16.
Fog, aerosol, and gas samples were collected during the winter of 1986 at Riverside, California. The dominant components of the aerosol were NH4+, NO3, and SO42−. Gaseous NH3 was frequently present at levels equal to or exceeding the aerosol NH4+. Maximum level were 3800, 3100, 690 and 4540 neq m−3 for NH4+, NO32− and NH3(g), respectively. The fogwater collected at Riverside had very high concentrations, particularly of the major aerosol components. Maximum concentrations were 26,000 29,000 and 6200 μM for NH4+, NO3 and SO42−, respectively. pH values in fogwater ranged from 2.3 to 5.7. Formate and acetate concentrations as high as 1500 and 580 μM, respectively, were measured. The maximum CH2O concentration was 380 μM. Glyoxal and methylglyoxal were found in all the samples; their maximum concentrations were 280 and 120 μM, respectively. Comparison of fogwater and aerosol concentrations indicates that scavenging of precursor aerosol by fog droplets under the conditions at Riverside is less than 100% efficient.The chemistry at Riverside is controlled by the balance between HNO3 production from NOx emitted throughout the Los Angeles basin and NH3 emitted from dairy cattle feedlots just west of Riverside. The balance is controlled by local mixing. Acid fogs result at Riverside when drainage flows from the surrounding mountains isolate the site from the NH3 source. Continued formation of HNO3(g) in this air mass eventually depletes the residual NH3(g). A simple box model that includes deposition, fog scavenging, and dilution is used to assess the effect of curtailing the dairy cattle feedlot operations. The calculations suggest that the resulting reduction of NH3 levels would decrease the total NO3 in the atmosphere, but nearly all remaining NO3 would exist as HNO3. Fogwater in the basin would be uniformly acidic.  相似文献   

17.
太湖湖滨带春季悬浮物沉降特征与水体营养盐响应   总被引:3,自引:2,他引:1  
为研究湖滨带悬浮物沉降过程中水体营养盐时空分布状况,在太湖西岸湖滨带典型区域进行原位沉降实验,计算了沉降量和沉降通量,并对沉降过程中TP、TN、NH+4-N、NO-3-N测定分析.结果表明,太湖西岸湖滨带沉降通量表现为人工芦苇区近岸无植被区自然芦苇区远岸无植被区,平均沉降通量分别为(1 383.40±925.60)、(1 208.67±743.50)、(278.72±142.53)、(245.58±154.25)g·(m2·d)-1,沉降第6 d以后沉降量稳定上升,沉降速率大于分解速率;经过持续15 d野外沉降实验观测,沉降过程中近岸带的TP含量是远岸带的2~3倍,且沉积物捕获器内NH+4-N和NO-3-N含量出现显著的差异(P0.01);沉降量与水体TN和NH+4-N含量呈显著相关(P0.01,n=42),表明沉降量的增加会导致上覆水体TN与NH+4-N含量增加;TN与NH+4-N相关系数为0.84,显示沉降量的增加可能加速氮素不同形态间相互转化,这一现象在当前太湖湖泛治理中应当予以重视.  相似文献   

18.
Measurements of gaseous HNO3, HCl and NH3 and particulate NO3, SO42−, Cl and NH4+ have been made at a small network of sites in eastern England using sampling intervals from 3 h to 7 days. Both HCl and HNO3 are spatially rather uniform, with some variation apparently due to spatial variations in NH3, which stoichiometrically exeeded the sum of both gaseous acids. Mean concentrations of NH3, HCl and HNO3 between February 1987 and January 1988 were 1.90, 0.67 and 1.01 μg m−3, respectively. Pollution roses revealed low NH3 concentrations, and high associated HCl and HNO3 with winds from the North Sea. HCl, but not HNO3 showed an appreciable elevation in concentration on the sector NW from our site, which we speculate may be due to the large capacity of coal-fired power stations in this upwind sector. Three-hourly data have been examined for diurnal effects and its is concluded that nocturnal formation of NO3 is occurring.  相似文献   

19.
The surface exchange of NH3 and HNO3 gases over heathland was measured with the aerodynamic gradient method in Leende,the Netherlands during April 25 and May 9,1991.Due to reactions in the system NH3,HNO3 and NH4NO3,the NH3 deposition flux is overestimated,while HNO3 shows apparent emission fluxes mostly during the field experiment.Results reveal that NH3 gradients are influenced slightly by HNO3 and the HNO3 gradients are strongly controlled by the NH3.A clear relationship between NH3 and HNO3 gradient is suggested by the Leende experiment. Before the late afternoon,NH3 deposition gradients will cause HNO3 upward gradients,meanwhile the NH3 gradients themselves will become smaller.After the HNO3 upward gradient reaches maximum,the NH3 deposition gradients will be enlarged or the emission gradients depressed,while the HNO3 upward gradients become smaller.  相似文献   

20.
采用溶液培养法,设置3个氮浓度20、100、200 mg·L-1和3个NH_4~+/NO_3~-比1∶0、0.5∶0.5、0∶1,研究污水氮浓度和NH_4~+/NO_3~-比对粉绿狐尾藻去氮能力和植物体氮组分的影响.结果表明,粉绿狐尾藻的生物量在第1周增长最快,其中氮浓度20 mg·L-1、100 mg·L-1时,生物量以NH_4~+/NO_3~-=1∶0处理最大;氮浓度200 mg·L-1时,以NH_4~+/NO_3~-=0.5∶0.5处理最大.粉绿狐尾藻在第1周对总氮、铵态氮和硝态氮去除速率最高,且随氮浓度升高而增加;氮浓度20 mg·L-1时,铵态氮和硝态氮的去除率无显著差异,氮浓度100 mg·L-1、200 mg·L-1时硝态氮的去除率高于铵态氮.粉绿狐尾藻氮积累量及对水体和底泥氮去除的贡献率均随氮浓度升高而增加,其氮含量和积累量均以第1周增长最快,氮浓度20 mg·L-1时氮积累贡献率以NH_4~+/NO_3~-=0∶1最大,氮浓度100 mg·L-1、200 mg·L-1时以NH_4~+/NO_3~-=0.5∶0.5最大.粉绿狐尾藻体内蛋白质、氨基态氮和硝态氮的含量均随氮浓度的升高而增加,且蛋白质氨基态氮硝态氮;NH_4~+/NO_3~-为1∶0和0.5∶0.5时蛋白质含量较高,NH_4~+/NO_3~-=1∶0时氨基态氮含量最高,NH_4~+/NO_3~-=0∶1时硝态氮含量最高.由此说明,在试验范围内,粉绿狐尾藻的去氮能力随污水氮浓度升高而提高,可以用于高氮浓度污水修复;粉绿狐尾藻喜铵态氮,但在100 mg·L-1以上的高氮浓度下以硝铵等比时生长和去除氮能力最强;粉绿狐尾藻体内氮组分受硝铵比调节,蛋白氮比例最高,铵态氮和硝态氮则分别随污水NH+4和NO-3比升高而提高.  相似文献   

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