Long-term measurements of SO2 dry deposition over Gansu Province, China

Reactive nitrogen (Nr) compounds comprise essential nutrients for plants. However, a large supply of nitrogen by fertilization through atmospheric deposition may be harmful for ecosystems such as peatlands and may lead to a loss of biodiversity, soil acidification and eutrophication. In addition, nitrogen compounds may cause adverse human health impacts. Large parts of Nr emissions originate from anthropogenic activities. &#160;Emission hotspots of &#931;Nr, i.e. the sum of all Nr compounds, are related to crop production and livestock farming (mainly through ammonia, NH3) and fossil fuel combustion by transport and industry (mainly through nitrogen oxides, NO2 and NO). Such additional amount of Nr will enhance its biosphere-atmosphere exchange, affect plant health and can influence its photosynthetic capacity. Therefore, it is necessary to thoroughly estimate the nitrogen exchange between biosphere and atmosphere.For measuring the nitrogen mixing ratios a converter for reactive nitrogen (TRANC: Total Reactive Atmospheric Nitrogen Converter) was used. The TRANC converts all reactive nitrogen compounds, except for nitrous oxide (N2O), to nitric oxide (NO) and is coupled to a fast-response chemiluminescence detector (CLD). Due to a low detection limit and a response time of about 0.3s the TRANC-CLD system can be used for flux calculation based on the eddy covariance (EC) technique. Flux losses, which are related to the experimental setup, different response characteristics and the general high reactivity of most N gases and aerosols, occur in the high frequency range. We estimated damping factors of approximately 20% with an empirical cospectral approach.For getting a reliable prediction of &#931;Nr fluxes through deposition models, long-term flux measurements offer the possibility to verify the nitrogen uptake capacity and to investigate exchange characteristics of &#931;Nr in different ecosystems.In this study, we compare modelled dry deposition fluxes using the deposition module DEPAC (DEPosition of Acidifying Compounds) within the chemical transport model LOTOS-EUROS (LOng Term Ozone Simulation &#8211; EURopean Operational Smog) against &#931;Nr flux measurements of the TRANC-CLD for a remote mixed forest site with hardly any local anthropogenic emission sources. This procedure allows to determine the background load and the natural exchange characteristics of nitrogen under low atmospheric concentrations. Therefore, the broad-scale dry deposition predicted directly by LOTOS-EUROS was compared to site-specific modelling results obtained using measured meteorological input data as well as the directly measured &#931;Nr fluxes. In addition, the influence of land-use weighting in LOTOS-EUROS was examined. We further compare our results to &#931;Nr deposition estimates obtained with canopy budget techniques. Measured &#931;Nr dry deposition at the site was 4.5 kg N ha-1 yr-1, in close agreement with modelled estimates using DEPAC with measured drivers (5.2 kg N ha-1 yr-1) and as integrated in the chemical transport model LOTOS-EUROS (5.2 kg N ha-1 yr-1 to 6.9 kg N ha-1 yr-1 depending on the weighting of land-use classes).Our study is the first one presenting 2.5 years flux measurements of &#931;Nr above a remote mixed forest. Further verifications of long-term flux measurements against deposition models are useful to improve them and result in better understanding of exchange processes of &#931;Nr.

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Effect of SO2 Dry Deposition on Porous Dolomitic Limestones

Materials ◽

10.3390/ma3010216 ◽

2010 ◽

Vol 3 (1) ◽

pp. 216-231 ◽

Cited By ~ 15

Author(s):

Mihaela Olaru ◽

Magdalena Aflori ◽

Bogdana Simionescu ◽

Florica Doroftei ◽

Lacramioara Stratulat

Keyword(s):

Dry Deposition ◽

So2 Dry Deposition

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Growth responses of ponderosa pine to long-term exposure to ozone, wet and dry acidic deposition, and drought

Canadian Journal of Forest Research ◽

10.1139/x93-010 ◽

1993 ◽

Vol 23 (1) ◽

pp. 59-66 ◽

Cited By ~ 40

Author(s):

Patrick J. Temple ◽

George H. Riechers ◽

Paul R. Miller ◽

Robert W. Lennox

Keyword(s):

Soil Water ◽

Sierra Nevada ◽

Water Availability ◽

Ponderosa Pine ◽

Dry Deposition ◽

Acidic Deposition ◽

Ambient Air ◽

Soil Water Availability ◽

Growth Responses

A 3-year field study of the cumulative effects of ozone (O3), wet and dry acidic deposition, and soil water availability was conducted on ponderosa pine (Pinusponderosa Laws.) in the Sierra Nevada of California from 1988 to 1990. Thirty-six 2-year-old potted seedlings were placed in each of 30 chambers and exposed from May through October to three levels of O3 (charcoal-filtered (CF), nonfiltered (NF), and NF plus 1.5 times ambient O3 (NF150)); three levels of acidity in simulated rain (pH 3.5, 4.4, 5.3); two levels of dry deposition (60 or 90% filtration), and two levels of soil water availability (well watered (WW) or drought stressed (DS)). An additional six plots served as ambient air (AA) controls. One-third (432) of the trees were harvested at the end of each exposure season. Low soil water availability was the only stress factor to significantly affect growth following the first exposure season. After the second season, O3 significantly reduced foliar biomass in WW–NF150 trees, but DS seedlings did not respond to O3. After 3 years of exposure, WW–NF150 trees averaged 70% loss of 1988 needles and 48% loss of 1989 foliage. Ozone-injured seedlings compensated for these losses by increased growth of current-year needles and stems and also increased growth of fine feeder roots. Radial stem growth and coarse-root growth were significantly reduced in O3-injured trees. DS trees in NF150 chambers averaged half the needle loss of WW trees and showed no reduction in radial growth in response to O3. Rain pH and dry deposition had no direct effects on growth of ponderosa pine. These cumulative responses to interacting stresses indicate the importance of multifactorial, long-term studies to evaluate forest tree responses to atmospheric deposition.

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Long-term Variation of Absorption and Total Aerosol Optical Properties over Typical Provinces of China from Satellite Observations

Journal of Physics Conference Series ◽

10.1088/1742-6596/2152/1/012001 ◽

2022 ◽

Vol 2152 (1) ◽

pp. 012001

Author(s):

Heng Li

Keyword(s):

Optical Properties ◽

Atmospheric Aerosols ◽

Guangdong Province ◽

Shandong Province ◽

Gansu Province ◽

Monthly Variation ◽

Aerosol Optical Properties ◽

Aerosol Emission ◽

Earth’S Climate

Abstract Increase of atmospheric aerosols has a profound impact on the Earth’s climate. It’s also one of the crucial factors that cuasesd more fequent air pollution events in China. Monthly average Aerosol Optical Depth (AOD) from MODIS and UltraViolet Absorbing aerosol Index (UVAI) from OMI during 2011 to 2019 are used to analyse the trend of absorption and total aerosol optical properties over three typical provinces of China, namely Shandong, Gansu and Guangdong provinces. The results show the average annual AOD of the three provinces are all decreasing while UVAI rises during this period. In addition, the monthly variation of AOD and UVAI are also obviously different over these provinces. In particular, the peak value of AOD appeared in July and the trough appeared in December over Shandong Province. And the peak appeared in April over Gansu Province, but AOD decrease slower then over Shandong Province. And there were two peaks in April and August over Guangdong Province. For UVAI, the peaks over Shandong and Gansu provinces both occur in January, while that over Guangdong Province appears in March. Above mentioned differences in the long-term trend and monthly variation of AOD and UVAI might be closely related to the meteorological conditions and aerosol emission of these three provinces.

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