Effects of acid deposition on forests in south China

１ＩｎｔｒｏｄｕｃｔｉｏｎＷｉｔｈｔｈｅｆａｓｔｇｒｏｗｉｎｇｏｆｍｏｄｅｒｎｉｎｄｕｓｔｒｙａｎｄｓｈａｒｐｌｙｉｎｃｒｅａｓｉｎｇｏｆｅｎｅｒｇｙｃｏｎｓｕｍｐｔｉｏｎｐｒｉｍａｒｉｌｙｃｏａｌ，ａｉｒｐｏｌｕｔｉｏｎａｎｄａｃｉｄｄｅｐｏｓｉｔ...     

Influence of acid deposition on atmospheric corrosion of zinc

Site exposure tests both open and sheltered have been carried out in acid deposition area in Southwest China. Results from six sites show that acid deposition exerts a great influence on atmospheric corrosion of Zn, and it is more serious in wet condition. Basically, Zn corrosion is directly proportional to time of exposure. While SO2 is the main pollutant of the atmosphere environment, Zn corrosion has a linear relationship to SO2 depositing rate and a hyperbolic to rain pH value.Observations by SEM, EDAX and X-ray diffraction show that under sheltered exposure condition, the corrosion products of Zn in heavy acid deposition area principally are sulphates.Based on the corrosion rates measured, the working life of galvanized steel can be predicated.     

The stem-II regional scale acid deposition and photochemical oxidant model—IV. The impact of emission reductions on mesoscale acid deposition in the lower ohio river valley

Assessment of the effect of reduction in emissions of primary sources on eventual levels of pollutants, pH of precipitation and total wet deposition is crucial in designing acid-rain control strategies. The STEM-II/ASM model is used to investigate the effect of reduction in emissions on the ultimate deposition patterns and amounts of major acidic pollutants in a mesoscale region. This work also investigates the effect of background levels of primary pollutant species on the eventual levels and deposition amounts of SO₄⁼ and NO₃⁻. A series of mesoscale simulations were conducted in which emissions of primary sources of NO_x and SO₂ were reduced and/or background concentrations of certain key species were changed. The results indicate that the dominant effect on the eventual deposition amounts of SO₄⁼ and NO₃⁻ is due to background concentrations of key precursor species such as SO_x and NO_x. With relatively high background concentrations, reducing SO₂ emissions by 50% and NO_x emissions by 40% resulted in reductions of 2–3% for SO₄⁼ wet deposition aand about 15% for NO₃⁻ wet deposition. However, reducing the background concentrations of SO₂ and SO₄⁼ by 50% and NO, NO₂ and HNO₃ by 40% resulted in substantial reductions in wet deposition; SO₄⁼ deposition was reduced by 40–50% and NO₃⁻ deposition was reduced by approximately 35%.     

Relative sensitivities of woody plants to acid deposition in south areas of China

Relative sensitivities of 30 species of common woody plants to simulated acid rain with pH values of 2.0, 2.5, 3.0, 3.5, 4.5 and control were studied. The results showed that 6 species of these plants were sensitive to simulated acid rain. The moderate included 18 species. The resistant included 6. Relative sensitivities to ambient acid rain and air pollutants and visible injury degree of 30 species of common woody plants in Chongqing City were investigated. Results showed that 6 species with foliage lesion rate at above 10 percent were sensitive, that 6 species with no lesion were resistant and that other 18 species with lesion at 10 percent below were moderate. Other 7 cities (Guiyang, Zunyi, Duyun, Changsha, Zhuzhou, Liuzhou and Guilin City) were also investigated and results were consistent with those of Chongqing City. The experimental and investigated results showed relative sensitivities and visible injury degree of woody plants to simulated acid rain were consistent with those of the woody plant     

Multivariate geostatistical trend detection and network evaluation of space-time acid deposition data—I. Methodology

A multivariate geostatistical technique is presented to address two key issues of trend detection and network evaluation of acid deposition data. The proposed technique is specifically designed to be compatible with the distinctive characteristics of acid deposition variables such as non-stationary of their spatial means, non-stationary of their spatial covariances, their complex periodic and non-periodic temporal trends, and the common imbalance between the availability of their spatial and temporal data. To accomplish this, the time series at each measurement point is viewed as a separate, but correlated one-dimensional regionalized variable. Each variable is assumed to be a sum of periodic (e.g. seasonal) and non-periodic (e.g. anthropogenic) temporal random variables, each characterized by its own temporal variogram. To obtain an initial estimate of the frequency of the involved periodic trends, direct quadratic spectrum estimation is conducted. Based on fitted direct and cross variograms, various forms of estimation such as co-kriging of non-periodic components can be performed. The estimated time series may then be tested for the presence of long-term trends. In addition, the fitted sill values of any variogram model at different stations form elements of a coregionalization matrix. This matrix may be regarded as the variance-covariance matrix for the particular temporal-trend scale presented by the variogram model. A coregionalization matrix can be used to generate a spatial correlogram. Viewing the estimated integral scale of each spatial correlogram as an indicator of the radius of information-influence of each measurement station, a monitoring network can be evaluated for its adequacy of coverage at different temporal-trend scales. A coregionalization matrix can also be decomposed through principal-component analysis in order to determine any potential spatial groupings and/or to generate regional indicators of changes at different temporal scales.     

Chance-constrained programming (CCP)abatement of SO_2 emission for acid deposition control in Liuzhou City

A deterministic linear programming model which optimizes the abatement of each SO2 emission source, is extended into a CCP form by introducing equations of probabilistic constrained through the incorporation of uncertainty in the source-receptor-specific transfer coefficients. Based on the calculation of SO2 and sulfate average residence time for Liuzhou City, a sulfur deposition model has been developed and the distribution of transfer coefficients have been found to be approximately log-normal. Sulfur removal minimization of the model shows that the abatement of emission sources in the city is more effective, while control cost optimization provides the lowest cost programmes for source abatement at each allowable deposition limit under varied environmental risk levels. Finally a practicable programme is recommended.     

Multivariate geostatistical trend detection and network evaluation of space-time acid deposition data—II. Application to NADP/NTN data

A multivariate geostatistical technique was presented in the first part of this paper (Rouhani et al., 1992, Atmospheric Environment 26A, 2603–2614) with the objective of addressing two key issues of trend detection and network evaluation of the acid deposition data. The investigated data include weekly reported SO₄²⁻ concentrations and depositions from 34 level-1 stations of the NADP/NTN. The duration of the available data ranges from 6 to 10 years. In order to extract the maximum amount of information from these relatively short time series, it is imperative to avoid any data reduction, such as integrating the data into seasonal or annual series. Direct quadratic spectrum estimation is applied to the data, which clearly indicates the presence of annual cycles in a large number of stations. Based on these preliminary results, measurement stations are grouped into three main eco-regions, including the Northeast/central, the West and the Midwest/Gulf regions. While the first two regions exhibit significant annual periodicities, the latter region does not show any significant cyclic characteristics. This analysis is followed by multi-scale temporal variography that further confirms the presence of periodic trends. Two types of time series are generated by co-kriging: (1) the non-periodic components at each station, and (2) the non-periodic regionalized factors for each region. Kendall's test for trend detection is applied to all generated time series, as well as to the original data. The results indicate that by geostatistical filtering of periodic components, the proposed procedure offers an efficient technique for trend detection. Using the estimated coregionalization matrices, spatial correlograms are generated for various temporal scales and regions. Viewing the estimated integral scale of each spatial correlogram as an indicator of the radius of information-influence of each measurement station, the NADP/NTN network is evaluated for its adequacy of coverage under different temporal scales.     

Limited acid deposition inferred from diatoms during the 20th century — A case study from lakes in the Tatra Mountains

Mountain lakes are usually sensitive to the effects of global and regional environmental changes. Since the second half of the 20th century, surface-water acidification has become a significant ecological problem, and many lakes in Europe and North America have anthropogenically acidified. Additionally, following reduction in emissions of sulfur (S) and nitrogen (N) compounds, recovery from acidification has been observed in many lakes. In this study, we used changes in diatom communities to reconstruct the pH histories based on changes recorded in nine Tatra lakes (Western Carpathians, Poland) since approximately 1850 AD. Overall, results indicate that acidic precipitation had little influence on lake-water pH in the Tatra Mountain lakes. Changes in diatom-inferred pH (DI-pH) generally were small and showed little evidence of acidification during the time of the highest air pollution (since the 1960s), and have shown little change since the reduction of acidic deposition since the 1990s. Lakes that showed some evidence of acidification included dystrophic lakes with low acid neutralizing capacity. However, as illustrated by the PCA trajectories of the diatom assemblages, the majority of the lakes currently contain diatom assemblages that are unlike the diatom floras that existed ca. 1850.     

Regional pattern of mercury wet deposition in Beijing

ＩｎｔｒｏｄｕｃｔｉｏｎＲｅｃｅｎｔｆｉｎｄｉｎｇｓｆｒｏｍｍｅｒｃｕｒｙｒｅｓｅａｒｃｈｉｎｄｉｃａｔｅｔｈａｔｔｈｅｍａｊｏｒｓｏｕｒｃｅｔｏｌａｋｅｓｉｓａｔｍｏｓｐｈｅｒｉｃｄｅｐｏｓｉｔｉｏｎ(Ｓｏｒｅｎｓｅｎ ,1990 ;Ｇｌａｓｓ,1990 ) ,ａｎｄｔｈａｔｓｉｇｎｉｆｉｃａｎｔｓｏｕｒｃｅｓｔｏｔｈｅａｔｍｏｓｐｈｅｒｅａｒｅｆｏｓｓｉｌｆｕｅｌｃｏｍｂｕｓｔｉｏｎａｎｄｉｎｃｉｎｅｒａｔｉｏｎｏｆｍｕｎｉｃｉｐａｌｓｏｌｉｄｗａｓｔｅａｎｄｓｌｕｄｇｅ(Ｇｌａｓｓ,1991;Ｗｈｉｔｅ ,1992 ;Ｃ…     

The buffering effects of aquatic sediments against acidic deposition

ＴｈｅｂｕｆｆｅｒｉｎｇｅｆｆｅｃｔｓｏｆａｑｕａｔｉｃｓｅｄｉｍｅｎｔｓａｇａｉｎｓｔａｃｉｄｉｃｄｅｐｏｓｉｔｉｏｎＬｉａｏＢｏｈａｎ；ＴａｎｇＨｏｎｇｘｉａｏ（ＲｅｓｅａｒｅｈＣｅｎｔｅｒｆｏｒＥｃｏ－ＥｎｖｉｒｏｎｍｅｎｔａｌＳｃｉｅｎｃｅｓ...     

Dry deposition inferential measurement techniques—I. Design and tests of a prototype meteorological and chemical system for determining dry deposition

A simple filterpack system and a supporting meteorological and surface-condition monitoring system have been deployed in a trial network to test methods by which dry deposition rates can be estimated on a routine basis, using average air concentration data and site-specific deposition velocities. The filterpack used in this dry deposition inferential measurement (DDIM) sampler differs from standard filterpacks by the use of a heated horizontal settling tube at the inlet. This modification is intended to protect the SO₂ sampling system from adverse effects associated with filter liquefaction at high humidities, while at the same time providing a simple means for eliminating large particles from the sampled air. Tests indicate that the sampler works well for SO₂ and for particulate species, and that HNO₃ concentrations are underestimated by about 25%. The DDIM approach differs from previous network measurement programs in that the data sets are designed to permit extension from observations at a subset of research sites to less intensive routine measurement sites. Hence a major goal is the definition of a suitable set of supporting data from which dry deposition rates can be inferred using air concentration data. Local vegetation characteristics are noted. At present, the additional variables that are monitored are solar radiation, wind speed, wind direction standard deviation, temperature, humidity, surface wetness, and precipitation. Observers report changes in the surrounding surface, such as the presence of snow or unusual drought.     

Critical load of sulfur deposition for ecosystemand its application in China

ＣｒｉｔｉｃａｌｌｏａｄｏｆｓｕｌｆｕｒｄｅｐｏｓｉｔｉｏｎｆｏｒｅｃｏｓｙｓｔｅｍａｎｄｉｔｓａｐｐｌｉｃａｔｉｏｎｉｎＣｈｉｎａＺｈａｏＤｉａｎｗｕ；ＺｈａｎｇＸｉａｏｓｈａｎ；ＹａｎｇＪｉａｎｘｉｎ（ＲｅｓｅａｒｃｈＣｅｎｔｅｒｆｏｒＥｃｏ－Ｅ...     

Adsorption of β-naphthalenesulfonic acid/sulfuric acid from their solution by weakly basic resin: equilibrium

Experiments for single and bisolute competitive adsorption were carried out to investigate the adsorption behavior of β-naphthalenesulfonic acid(NSA) and sulfuric acid (H2 SO4 ) from their solution at 25 ℃ onto weakly basic resin D301R. Adsorption affinity of sulfuric acid on D301R was found to be much higher than that of NSA. The data of single-solute adsorption were fitted to the Langmuir model and the Freundlich adsorption model. The ideal adsorbed solution theory(IAST) coupled with the single-solute adsorption models were used to predict the bisolute competitive adsorption equilibria. The IAST coupled with the Langmuir and the Freundlich model for sulfuric acid and NSA, respectively, yields the favorable representation of the bisolute competitive adsorption behavior.     

Adsorption of β-naphthalenesulfonic acid/sulfuric acid from their solution by weakly basic resin: equilibrium

Experiments for single and bisolute competitive adsorption were carried out to investigate the adsorption behavior of β-naphthalenesulfonic acid(NSA) and sulfuric acid (H2SO4) from their solution at 25℃ onto weakly basic resin D301R. Adsorption affinity of sulfuric acid on D301R was found to be much higher than that of NSA. The data of single-solute adsorption were fitted to the Langmuir model and the Freundlich adsorption model. The ideal adsorbed solution theory(lAST) coupled with the single-solute adsorption models were used to predict the bisolute competitive adsorption equilibria. The lAST coupled with the Langmuir and the Freundlich model for sulfuric acid and NSA, respectively, yields the favorable representation of the bisolute competitive adsorption behavior.     

Wet air oxidation treatment of H acid wastewater

１ＩｎｔｒｏｄｕｃｔｉｏｎＨａｃｉｄｍｏｎｏｓｏｄｉｕｍｓａｌｔ（４ａｍｉｎｏ５ｈｙｄｒｏｘｙ２，７Ｎａｐｈｔｈａｌｅｎｅｄｉｓｃｕｌｆｏｎｉｃａｃｉｄｍｏｎｏｓｏｄｉｕｍｓａｌｔ，ｈｅｒｅｉｎａｆｔｅｒｒｅｆｅｒｅｅｄｔｏａｓ“Ｈａ...     

Photodegradation of α-naphthaleneacetic acid in aqueous solution

Ｉｎｔｒｏｄｕｃｔｉｏｎα ｎａｐｈｔｈａｌｅｎｅａｃｅｔｉｃａｃｉｄ (ＮＡＡ)ｉｓａｎｉｍｐｏｒｔａｎｔｐｌａｎｔｇｒｏｗｔｈｒｅｇｕｌａｔｏｒｕｓｅｄｎｏｔｏｎｌｙｔｏｐｒｅｖｅｎｔｔｈｅｐｒｅｈａｒｖｅｓｔｄｒｏｐｏｆａｐｐｌｅｓｂｕｔａｌｓｏａｓａｆｒｕｉｔｔｈｉｎｎｉｎｇａｇｅｎｔ (Ｗｏｒｔｈｉｎｇ ,1991) .ＭｕｃｈｒｅｓｅａｒｃｈｗｏｒｋａｂｏｕｔｔｈｅｅｆｆｅｃｔｏｆＮＡＡｏｎｐｌａｎｔｔｉｓｓｕｅｓ(Ｓｐｅｅｒ,1993;Ｈｉｄｅｙｏｓｈｉ,1993;Ｐｒａｓｄ ,1994 ) ,ｐｌａｎｔｇｒｏｗｔｈａ…     

Dry deposition of atmospheric aerosols by dual tracer method — I. Area source

Aerosol deposition velocities can be estimated from measurements of the ratio of the concentration of a depositing species, such as Pb, to a non-depositing (conserved) species, such as CO, when both originate from the same source (dual tracer method). This method has been applied to size-segregated aerosol samples collected in Los Angeles, CA during the Southern California Air Quality Study, summer 1987. Lead size distributions were measured in ambient and tunnel samples using an eight-stage low pressure impactor. A new parameter, the fraction of aerosol remaining airborne, was directly determined. This fraction is of great importance receptor modelling. Dry deposition velocities calculated using a stirred atmosphere (box) model, varied over three orders of magnitude depending on particle size. The calculated deposition velocity for unit density particles > 0.5 μm, was approximately proportional to D_p² as expected for deposition by an interception mechanism (d_p = particle aerodynamic diameter).     

Terephthalic acid wastewater treatment by using two-stage aerobic process

１ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｔｅｒｅｐｈｔｈａｌｉｃａｃｉｄ（ＰＴＡ）ｗａｓｔｅｗａｔｅｒｃｏｎｔａｉｎｓｔｅｒｅｐｈｔｈａｌｉｃａｃｉｄ（ＴＡ），ａｃｅｔｉｃａｃｉｄａｎｄｍｅｔｈｙｌａｃｅｔａｔｅ，ａｎｄｓｏｏｎ（Ｔａｂｌｅ１）．ＰＴＡｗａｓ...