Three-year monitoring results of nitrate and ammonium wet deposition in Thailand

Wet deposition is one of the important sources of nitrogen input into the ecosystem. It also contributes to rain acidity in some environments. In this study we reported the annual as well as seasonal trends of nitrogen wet deposition at three locations in Thailand: Bangkok, Chiang Mai and Nan. Comparison of nitrogen wet deposition between in rural and in the urban areas was also made. Daily rainfall was measured and monthly rainwater was collected for nitrogen analysis during 1999–2002. The average NO₃ ^– concentration in rainwater collected from the rural sites (60 km from urban area) was around 0.2–0.3 mg L^–1, while that from the urban areas of Chiang Mai and Nan cities it was 0.4–0.5 mg L^–1. NH₄ ⁺ concentration in rainwater showed the similar ranges to that of NO₃ ^– , except at Nan where concentration was not significantly different between the urban and rural sites. On the other hand, the average concentrations of NO₃ ^– were higher at Bangkok site than other sites, while concentration of NH₄ ⁺ was almost the same between Chiang Mai and Bangkok. Wet deposition of NO₃ ^– at the rural sites of Chiang Mai and Nan ranged from 2.1 to 3.2 kg N ha^–1 yr^–1, while at the urban sites this ranged from about 6 kg N ha^–1 yr^–1 in Chiang Mai and Nan Cities to 8.6 kg N ha^–1 yr^–1 in Bangkok. Wet deposition of NH₄ ⁺ at the rural sites of Chiang Mai and Nan was about 2.4 to 3.6 kg N ha^–1 yr^–1 and at the urban sites of Chiang Mai, Nan and Bangkok this was 7.7, 4.9 and 8.1 kg N ha^–1 yr^–1, respectively. Thus, it was concluded that wet deposition of both nitrogen species was significantly higher at the urban sites than at the rural sites.     

太湖氮磷大气干湿沉降时空特征

为了探索太湖氮磷营养盐干湿沉降特征及对太湖营养盐输入的贡献,于2011年不同季节采集太湖不同位点的大气干湿沉降样品,分析干湿沉降中氮（N）和磷（P）的形态和沉降量。研究结果表明,输入太湖的磷以干沉降为主,而氮以湿沉降为主。在太湖干沉降中总无机氮（TIN）占总氮（TN）的77.1%,溶解性磷（DIP）占总磷（TP）的77.9%。干沉降中TIN主要以NH+4-N为主。西太湖是TN与TP通过大气干湿沉降输入太湖的最高湖区。太湖全年大气TN沉降总量为20 978 t,TP沉降总量为1 268 t,因此,氮磷大气干湿沉降是太湖营养盐输入的重要来源之一。     

Particulate emission inventory and trends in ambient particulate matter concentrations in the Czech Republic between 1993 and 1999

Trends in total suspended particulates (TSP) emissioninventories were compared with ambient TSP concentrationsduring the period of 1993-1999 in the Czech Republic. TheTSP annual emission decreased within the period of observationfrom 441 300 to 67 000 of metric tonnes (by 85%). During thesame period a less pronounced downward trend from80.3 g m^-3 to 31.5g m^-3 (decrease by 61%)was noted also for the ambient TSP annual average. Differencebetween the two air quality indicators seems to indicate thatchanges in TSP emission inventories from year to year arebeing to some extent overestimated. Monthly ambientparticulate concentrations did not respond to overall drop inemissions proportionately but were closely associated withmonthly mean temperatures. While in the winter the correlationbetween ambient TSP and temperature was negative, in summerthe correlation between the two variables was positive. Inspring and autumn there was no clear correlation betweentemperature and ambient particulate pollution. The improvementof air quality in the Czech Republic since the economical andpolitical transformation in 1990s is substantial whendemonstrated by emission figures, however, true state ofparticulate pollution expressed by ambient levels requiresfurther attention.     

Atmospheric concentrations of nitric acid, sulfur dioxide, particulate nitrate and particulate sulfate, and estimation of their dry deposition on the urban- and mountain-facing sides of Mt. Gokurakuji, Western Japan

Atmospheric concentrations of nitric acid (HNO₃), sulfur dioxide (SO₂), particulate nitrate and particulate sulfate on the urban- and mountain-facing sides of Mt. Gokurakuji were measured from November 2002 to October 2003, in order to evaluate the effects of anthropogenic activity on air quality and dry deposited nitrate and sulfate on the surfaces of pine foliage. The results showed that HNO₃, SO₂ and concentrations were significantly higher (P < 0.05) on the urban-facing side (1.54, 2.48 and 0.65 μg m⁻³, respectively) than the mountain-facing side (0.67, 1.19 and 0.37 μg m⁻³, respectively), while concentrations did not differ significantly between the two sides (urban-facing: 2.80 μg m⁻³; mountain−facing: 2.05 μg m⁻³). Indirect estimates of dry deposition rates of nitrate and sulfate to the surfaces of pine foliage based on the measured concentrations approximately agreed with the measured values determined by the foliar rinsing technique in a previous study. It was found that HNO₃ was the major source (approximately 80%) of dry deposited nitrate on pine foliage, while the contribution from was about equal to that from SO₂. In conclusion, HNO₃ and SO₂ appear to be dominant species reflecting higher dry deposition rates of nitrate and sulfate on the urban-facing side compared to the mountain-facing side of Mt. Gokurakuji.