Atmospheric Deposition of Nitrogen and Sulfur in the Yellow Sea Region: Significance of Long-Range Transport in East Asia

The amounts of nitrogen and sulfur deposited in the region of the Yellow Sea in both dry and wet forms were estimated focusing on the period between 1999 and 2000. Dry deposition fluxes were obtained using concentrations from ground stations on both Korean and Chinese sides and from shipboard and aircraft measurements. Wet deposition fluxes were determined at ground stations on the Korean side. The dry deposition flux over the Yellow Sea was much greater than those for other world oceans. As a whole, the amounts of wet depositions of nitrogen and sulfur were 1.9 and 1.5 times larger than the amounts of respective dry depositions. Substantial influence from China caused by high emissions in East China and westerly wind was possibly suggested. However, the influence from nitrogen emission in Korea was also confirmed.     

A Numerical Simulation of Acid Deposition in East Asia

The goal of the present study is to do a long term simulation and to derive a source receptor-relation using a comprehensive Eulerian acid deposition model coupled with a dynamic meteorological model. The selected modeling period is from March 1 to April 30, 1996. A dynamic meteorological model named MM5 was first used to calculate meteorological fields and then STEM preprocessors were invoked to generate dry deposition velocities and eddy diffusivities. Finally, a multi-scale STEM was applied to simulate both wet and dry acid deposition phenomena. The source-receptor relations were also estimated for sulfate and nitrate species using a counter species method. The model results for SO₂ and O₃ agree very well with measurements. However the model under-predicts the NO₂ concentration due to insufficient grid resolution as well as due to inaccurate field measurement. The transport contribution for total mass and wet deposition is much larger than that of dry deposition.     

Transport of Atmospheric Pollutants from East Asia

Air-borne measurements of air pollutants transported from northeast Asia to Japan and the Pacific Ocean were carried out three times from 1996 to 1999 over the seas between Japan and Asian Continent. Those campaigns were named PEACAMPOT II under auspices of the IGAC/APARE program. A transport pattern of a highly polluted air mass from central China was found. Such air mass was driven by the quick movement of low pressure traveling from Taiwan area to the northeast of Japan. This finding supported well the results of modeling studies for long-range transport of atmospheric pollutants from East Asia.     

Effects of Acid Deposition on Urushi Lacquer in East Asia

Urushi (Japanese lacquer) plates were exposed to indoor air in 7 cities in East Asia from summer 1995 through winter 1997. The plates, collected every 3 months, were optically observed by using a gloss meter, a digital microscope and a microscopic infrared spectrophotometer for evaluation of a seasonal impact by acidic air pollutants. The gloss losses were high on the urushi surface in autumn, when fog frequently appeared. Numerous fine spots were observed in 0.2–0.3 mm in diameter on the surfaces of the plates exposed at Chongqing, China, Taejon, Korea and Nara, Japan, where dense fog occurred. The spots were dark and opaque at Chongqing, where heavy air pollution was observed. A dark and opaque core was observed in each semitransparent spot at Taejon and Nara, while no spots were observed at Kyoto and Ishikawa, where fog often appeared but air pollution was at a low level. Carbonyl group, identified by microscopic infrared spectrometry, was found in the spots on the urushi surfaces. The carbonyl group may be formed by oxidation of a side-chain in urushiol (a major component of urushi sap, alkyl phenol). Urushi lacquer may be damaged by high concentration of sulfate anion, included in acid fog.     

Step-By-Step Approach to Establish Acid Deposition Monitoring Network in East Asia (EANET): Thailand's Experiences

Recognizing the adverse effects of acid deposition and its transboundary nature, efforts have been made for the past six years by countries in the East Asian region to establish acid deposition monitoring network in the region by taking a step-by-step approach towards the formal establishment. The First Intergovernmental Meeting held in March 1998 agreed as the first step to implement preparatory-phase activities for two years with the aim to officially establish the EANET in the year 2000. With the successful implementation of the preparatory-phase activities, the Second Intergovernmental Meeting held in October 2000 subsequently agreed to start the activities of the EANET on a regular basis from January 2001. Thailand developed and carried out the national monitoring plan for the preparatory-phase activities through the cooperation of various agencies. Four monitoring sites were included in the preparatory-phase activities of the EANET. Monitoring capacity in Thailand has been gradually built during the preparatory-phase and Thailand is now ready to start monitoring activities of the EANET on a regular basis. Efforts should be continued to study the complex nature of acid deposition phenomena, to quantify the adverse environmental impacts of acid deposition, and to eventually reduce emissions of acid precursors. Strong supports from international and regional organizations are essential for effective implementation of the EANET activities and to address acid deposition problem in the East Asian region.     

Sulfur Deposition in Asia: Seasonal Behavior and Contributions from Various Energy Sectors

Sulfur transport and deposition in Asia, on an annual andseasonal basis, is analyzed using the ATMOS model. Calculationsare performed for two complete years (1990 and 1995). Deposition amounts in excess of 0.5 g S m^-2 yr^-1 are estimated for large regions in Asia, with values as high as 10 g S m^-2 yr^-1 in southeastern China. Annual averaged SO₂ concentrations in excess of 20 μg SO₂ m^-3 are calculated for many urban and suburban areas ofeastern China and S. Korea, with an average of 5 μg SO₂ m^-3 over most of the emitter regions. Sulfur deposition by major source categories is also studied. Southeast Asia (Indonesia, Malaysia, Philippines, Singapore)receives ～25% of its sulfur deposition from shipping activities. Sulfur deposition from bio-fuel burning is significant for most of the underdeveloped regions in Asia. Volcanoes are a major source of sulfur emissions in the PacificOcean, Papua New Guinea, Philippines and Southern Japan. Sulfur deposition is shown to vary significantly throughout the year.The monsoons are found to be the largest factor controlling sulfur transport and deposition in the Indian sub-continent andSoutheast Asia. India receives over 35% of its total depositionduring the summer months. In East Asia, sulfur deposition isestimated to be 10% higher during summer and fall than winterand spring. Model results are compared with observations from a number of monitoring networks in Asia and are found to be generally consistent with the limited observations.     

Quality Control and Its Constraints during the Preparatory-Phase Activities of the Acid Deposition Monitoring Network in East Asia (EANET)

Participating countries of the Acid Deposition Monitoring Network in East Asia (EANET) launched the preparatory-phase activities from April 1998. For the recognition and improvement of the analytical precision and accuracy, the Interim Network Center (INC) carried out the inter-laboratory comparison on the analysis of artificial rainwater samples and soil samples. Relevant laboratories submitted their analytical data to the INC for the evaluation. Submitted data were summarized and evaluated in terms of precision and accuracy, and were compared with the Data Quality Objectives (DQOs) of EANET. These inter-laboratory comparisons made clear the present conditions of laboratories as well as the major constraints that should be solved in the future.     

Long-Range Transport of Sulfur from Northeast Asia to Chengshantu, Shandong Peninsula: Measurement and Simulation

Observations of air pollutants were conducted at Chengshantu in January 1996 to clarify the extent of trans-boundary pollution from the Asian continent. A nested air quality prediction modeling system (NAQPMS), which included parameters on emission, transport, diffusion, deposition and transformation of sulfur oxides, was performed to compile sulfur concentrations over the observation site. The model calculation reproduced the observed variations of sulfur oxides and sulfate well, although the model calculations could not reproduce the extensively low sulfate concentrations. Using nesting improves the ability of the modeling system to capture peak episodes seen in the observations. Calculation of the origins of deposited sulfur in each country with the NAQPMS shows that the long-range transport of sulfur is very serious. For Japan, 49% of sulfur deposition was from other countries during the campaign period.     

Trace Element Profiles in Ombrogenous Peat Cores from Norway: Evidence of Long Range Atmospheric Transport

Concentrations of Pb, Cd, As, Sb, and Se in peat from 21 ombrotrophic bogs in Norway are discussed with respect to air pollution and compared to other evidence from studies of trace element deposition in Norway. In general the data support conclusions from studies of atmospheric deposition based on moss analysis, and they also confirm specific trends previously observed for the contamination of natural surface soils with these elements. Lead, Cd, As, and Sb all are strongly enriched in the surface peat layers, indicating significant atmospheric input all over the country. In the south the concentrations in the surface peat are about 10 times higher than in the central and northern part of the country, supporting previous evidence of substantial input from source regions in other European countries. For Se there is also a component of anthropogenic input in the south, but this contribution from long range transport is superimposed on a very distinct coast - inland gradient all along the west coast, strongly suggesting atmospheric supply of Se from the marine environment.     

A Model Analysis of Transport of Sulfur Oxides in China and Outflow to the Sea

A numerical analysis of modeled long-range transport of sulfur oxides in the continental areas of East Asia with some verification was introduced. Although several modeling studies on acidic deposition in East Asia have been done, only few cases have verified in wide areas. In this study, the model calculation has been compared with the monthly averaged sulfur concentration in precipitation observed at 69 locations widely covering China from July 1992 through January 1993. Additionally, the atmosphericSO₂ ⁹⁰Sr concentration along the east coast of the continent was also compared with the observation in May 1993, and found to be reasonably consistent. Basing on these comparisons, the budget of sulfur oxides in China, especially about the outflow from the east coast to the sea areas was examined considering the seasonal variation of distribution of wet deposition and the pathways of atmospheric sulfur oxides. The seasonal variation of these indices was found to have large difference between the north and the south of 35°N. The outflow from the east coast increased remarkably in winter due to the decrease of deposition in the inland areas along the transport pathways.     

Calculating Critical Loads of Sulfur Deposition for 100 Surface Waters in China Using the Magic Model

Although decades of acid deposition have apparently not resulted in surface water acidification in China, some surface waters may have the potential trend of being acidified, especially those in southern China. In this paper, a dynamic acidification model–MAGIC was applied to 100 surface waters in southern and northeastern China to evaluate the impact of acid deposition to surface waters and to determine their critical loads of S deposition, both regions having distinguishing soil, geological and acid deposition characteristics. Results indicate that most surface waters included in this paper are not sensitive to acid deposition, with critical loads of S for these waters comparatively high. On the other hand, surface waters in southern China, especially those in Fujian, Jiangxi and Guangdong provinces, are more susceptible to acidification than those in northeastern China, which coincides with their different patterns of soil, geological and acid deposition conditions. Among all the waters, a few small ponds, such as those on top of the Jinyun mountain and Emei mountain, are the most sensitive to acid deposition with critical loads of 1.84 and 3.70 keq·ha^?1·yr^?1, respectively. For the considerable ANC remaining in most 100 surface waters, it is not likely that acidification will occur in the near future for these waters.     

Modelling of Atmospheric Transport and Deposition of Pesticides

Modelling of atmospheric transport and deposition of pesticides is presented and discussed. Modelling on regional scale builds on the existing knowledge gained in other air pollution fields. An overview of current modelling studies on transport and deposition on a regional scale (typically 30-3000 km) is given. From these studies it is concluded that the models are capable in simulating the spatial distribution of the concentrations and depositions. However, large uncertainties are present in this type of modelling and are for the greater part induced by the uncertainty in the emissions and subsequently in the exchange process parameterisations and the physicochemical properties needed in the parameterisations. Many more measurement data are needed to validate the models.     

NMVOCs and CO Emission Inventory in East Asia

For analyzing acidification in East Asia, long range transportation models has been developed, which require emissions inventories of the precursors. SO₂ and NOx emissions inventories were reported previously; here emissions of NMVOCs (Non methane volatile organic compounds) and CO in East Asia; China, Republic Korea, Japan and Taiwan area, are estimated. For the years 1994–95, the total emissions of NMVOC and CO in East Asia are estimated at 17.7 and 94.1Tg/y respectively. Small coal boiler and biomass use for residences are dominant sources of NMVOCs in the area, especially in China. More than half of CO emission comes from biomass use in residences in China. Regionally at east costal area in China high density emission is seen in the 1×1 degree grid emission map.     

A Case Study on Estimation of Dry Deposition of Sulfur and Nitrogen Compounds by Inferential Method

In order to estimate dry deposition, deposition velocity calculation and concentration measurement were carried out in Niigata, Japan. Deposition velocities of SO₂ and HNO₃ for some surfaces such as coniferous forest, deciduous forest, agricultural land, and water were calculated taking into account diurnal variations of meteorological elements using routine meteorological data. Deposition velocities of fine and coarse aerosols were also estimated respectively. Concentrations of SO₂, HNO₃, sulfate and nitrate in fine and coarse aerosols respectively were measured from July to December in 1998 using filter pack and denuder methods. The results indicate that HNO₃ dry deposition for the high aerodynamic roughness surfaces such as forests is quite large. It is suggested that sulfate and nitrate aerosols depositions as well as the gases depositions should be taken into account to estimate dry deposition of sulfur and nitrogen compounds. It is also indicated that dry depositions of sulfur and nitrogen compounds are unable to ignore compared with their wet depositions.     

Nitrogen and Sulfur Deposition and Forest Nutrient Status in the Valley of Mexico

Mexico City experiences some of the most severe air pollution in the world. Ozone injury has been documented in sensitive tree species in urban and forested areas in the Valley of Mexico. However, little is known of the levels of other atmospheric pollutants and their ecological effects on forests in the Valley of Mexico. In this study bulk throughfall deposition of inorganic nitrogen (N) and sulfur (S) was measured for one year at a forested site upwind (east) and downwind (southwest) of Mexico City. Edaphic and plant (Pinus hartwegii Lindl.) indicators of N and S nutrient status were also measured. Streamwater NO₃ ^- and SO₄ ^2- concentrations were also determined as an indicator of watershed-level N and S loss. Annual bulk throughfall deposition of inorganic N and S at the high-pollution forested site 23 km southwest of Mexico City (Desierto de los Leones National Park; DL) was 18.5 and 20.4 kg ha^-1. Values for N and S deposition at Zoquiapan (ZOQ), a relatively low-pollution site 53 km east of Mexico City, were 5.5 and 8.8 kg ha^-1 yr^-1. Foliar concentrations of N, foliar N:P and C:N ratios, extractable soil NO₃ ^-, and streamwater NO₃ ^- concentrations indicate that the forest at DL is N enriched, possibly as a result of chronic N deposition. Sulfur concentrations in current-year foliage were also slightly greater at DL than at ZOQ, but S concentrations in one-year-old foliage were not statistically different between the two sites. Streamwater concentrations of NO₃ ^- ranged from 0.8 to 44.6 μEq L^-1 at DL compared to 0.0 to 11.3 μEq L^-1 at ZOQ. In summary, these findings support the hypothesis that elevated N deposition at DL has increased the level of available N, increased the N status of P. hartwegii, and resulted in export of excess N as NO₃ ^- in streamwater.     

Global Model Simulations of the Transport of Asian and Sahara Dust: Total Deposition of Dust Mass in Japan

We simulated the global transport of dust emitted from all major dust source regions on earth by using a global three-dimensional chemical transport model for the year 2000. A modified dust emission flux scheme and an advanced nonlocal diffusion scheme for accurately determining the atmospheric eddy diffusivity in the atmospheric boundary layer were implemented to improve the chemical transport model. We specifically examined and analyzed dust storms that occurred in China and northern Africa. Four scenarios representing the global transport of dust from dust storms originating in the Loess region and the Gobi, Takla Makan, and Sahara deserts, respectively, were simulated. The results of each scenario were then compared with those resulting from all major dust source regions on earth, to identify which deserts have a major impact on dust transport and its deposition in Japan. The dust from the Sahara desert, most from the western part that was found in this study, reached Japan in 9–10 days, while Gobi and Loess region dust took 2 to 3 days, and 4 days for Takla Makan dust. The model-calculated monthly total deposition of dust mass from all major dust source regions was compared with comprehensive measurements of total deposition collected at sampling stations distributed over Japan, and good agreement was generally found. From these analyses, it was also indicated that dust emitted from other deserts, including the Turkestan, Iranian, and Arabian, could have a significant impact on dust deposition on Japan.     

The Study of Atmospheric Transport and Deposition of Cadmium Emitted from Primitive Zinc Production Area

Laoyingshan town lead zinc mine is one of the important zinc production centers in Guizhou province, China. The cadmium (Cd) is one of the mineral resources associated of lead zinc mine. The exploitation and uses of lead zinc mine would lead to Cd pollution to the environment. Soil Cd concentrations in this area are elevated by 30–50 times compared to the national background value in soil which is 0.279 mg kg^?1. In situ air Cd concentrations air/soil Cd fluxes were measured at 26 sampling sites in Laoyingshan town by moss bag from Jan. to Sep. 2005. The results showed that the average Cd concentration of total suspended particulates (TSP) and soil were 5.3 and 4.6 times higher than those measured at downwind direction 10 km due to a large amount of Cd emission from traditional melting. The results showed a clear decreasing trend along with the distance increasing from the pollution source for all the study parameters, namely cadmium contents in soil and TSP and deposition rate determined using moss-bag method. The results are consistent with the studied results previously. The correlations between Cd fluxes and soil show the relationship between the content in atmospheric TSP and spatial distribution of deposited heavy metal. The authors found that air spread is the major route of Cd pollution.     

Modeling studies on sulfur deposition and transport in East Asia

A three dimensional regional Eulerian model of sulfur deposition and tranport has been developed. It includes emission, transport, diffusion, gas-phase and aqeous-phase chemical process, dry depostion, rainout and washout process. A looking up table method is provided to deal with the gas-phase chemical process including sulfur transfer. Calculated values have reasonable agreement with observations. Distribution of sulfur deposition and transport in East Asia are also analyzed in the paper. Simulation shows that sulfate (SO ₄ ^2– ) is the main substance to transport in long range transport. Some amount of sulfur emission of different countries transport across boundaries, but the main origin of sulfur deposition in each country in East Asia is from herself. Furthermore, some transport paths on different layers and outlet or inlet zones are found.     

Al and Fe in PM 2.5 and PM 10 Suspended Particles in South-Central Florida: The Impact of the Long Range Transport of African Mineral Dust

Aluminum and iron were measured in daily samples collected at urban and rural sites near Ft. Myers, Florida, in 1995–1996 using a dichotomous sampler. Al and Fe concentrations were low during most of the year but they increased dramatically duringsummer when African dust was advected into Florida. The ratioof fine (less than 2.5 m diameter) to coarse (2.5–10 m) Al and Fe is relatively constant in African dust events with the fine accounting for a third to a half of the total. Also the mass ratio of Al-to-Fe is relatively constant at 1.8, a value similar to average crustal material. In contrast, in non-African dust the fine-to-coarse and Al-to-Fe ratios are extremely variable and generally much lower than those duringAfrican events when dust concentrations ranged up to 86 g m^-3. The timing and magnitude of the Ft. Myers dust peaks closely matched those measured concurrently in Miami, 200 km to the southeast. Large areas of the eastern United States are frequently impacted by African dust every summer. Although dustconcentrations can reach very high values it seems unlikely that African dust events alone will cause a violation of the Environmental Protection Agency's standards for PM 2.5 or PM 10. However, African dust in conjunction with emissions from local and regional sources could conceivably present a problemwith compliance. The probability of such an occurrence is heightened by the fact that dust concentrations are highest in the summer when pollution levels are often at a maximum in theeastern states.