Wet precipitation chemistry at a high-altitude site (3,326 m a.s.l.) in the southeastern Tibetan Plateau

This paper presents the results of wet precipitation chemistry from September 2009 to August 2010 at a high-altitude forest site in the southeastern Tibetan Plateau (TP). The alkaline wet precipitation, with pH ranging from 6.25 to 9.27, was attributed to the neutralization of dust in the atmosphere. Wet deposition levels of major ions and trace elements were generally comparable with other alpine and remote sites around the world. However, the apparently greater contents/fluxes of trace elements (V, Co, Ni, Cu, Zn, and Cd), compared to those in central and southern TP and pristine sites of the world, reflected potential anthropogenic disturbances. The almost equal mole concentrations and perfect linear relationships of Na⁺ and Cl^? suggested significant sea-salts sources, and was confirmed by calculating diverse sources. Crust mineral dust was responsible for a minor fraction of the chemical components (less than 15 %) except Al and Fe, while most species (without Na⁺, Cl^?, Mg²⁺, Al, and Fe) arose mainly from anthropogenic activities. High values of as-K⁺ (anthropogenic sources potassium), as-SO₄ ^2?, and as-NO₃ ^? observed in winter and spring demonstrated the great effects of biomass burning and fossil fuel combustion in these seasons, which coincided with haze layer outburst in South Asia. Atmospheric circulation exerted significant influences on the chemical components in wet deposition. Marine air masses mainly originating from the Bay of Bengal provided a large number of sea salts to the chemical composition, while trace elements during summer monsoon seasons were greatly affected by industrial emissions from South Asia. The flux of wet deposition was 1.12 kg?N?ha^?1?year^?1 for NH₄ ⁺–N and 0.29 kg?N?ha^?1?year^?1 for NO₃ ^?–N. The total atmospheric deposition of N was estimated to be 6.41 kg?N?ha^?1?year^?1, implying potential impacts on the alpine ecosystem in this region.     

Sulfur Dioxide and Nitrogen Oxides Emissions from U.S. Pulp and Paper Mills, 1980–2005

Abstract

Comprehensive surveys conducted at 5-yr intervals were used to estimate sulfur dioxide (SO₂) and nitrogen oxides (NO_x) emissions from U.S. pulp and paper mills for 1980, 1985, 1990, 1995, 2000, and 2005. Over the 25-yr period, paper production increased by 50%, whereas total SO₂ emissions declined by 60% to 340,000 short tons (t) and total NO_x emissions decreased approximately 15% to 230,000 t. The downward emission trends resulted from a combination of factors, including reductions in oil and coal use, steadily declining fuel sulfur content, lower pulp and paper production in recent years, increased use of flue gas desulfurization systems on boilers, growing use of combustion modifications and add-on control systems to reduce boiler and gas turbine NO_x emissions, and improvements in kraft recovery furnace operations.     

Simulating chemistry–aerosol–cloud–radiation–climate feedbacks over the continental U.S. using the online-coupled Weather Research Forecasting Model with chemistry (WRF/Chem)

The chemistry–aerosol–cloud–radiation–climate feedbacks are simulated using WRF/Chem over the continental U.S. in January and July 2001. Aerosols can reduce incoming solar radiation by up to ?9% in January and ?16% in July and 2-m temperatures by up to 0.16 °C in January and 0.37 °C in July over most of the continental U.S. The NO₂ photolysis rates decrease in July by up to ?8% over the central and eastern U.S. where aerosol concentrations are high but increase by up to 7% over the western U.S. in July and up to 13% over the entire domain in January. Planetary boundary layer (PBL) height reduces by up to ?23% in January and ?24% in July. Temperatures and wind speeds in July in big cities such as Atlanta and New York City reduce at/near surface but increase at higher altitudes. The changes in PBL height, temperatures, and wind speed indicate a more stable atmospheric stability of the PBL and further exacerbate air pollution over areas where air pollution is already severe. Aerosols can increase cloud optical depths in big cities in July, and can lead to 500–5000 cm^?3 cloud condensation nuclei (CCN) at a supersaturation of 1% over most land areas and 10–500 cm^?3 CCN over ocean in both months with higher values over most areas in July than in January, particularly in the eastern U.S. The total column cloud droplet number concentrations are up to 4.9 × 10⁶ cm^?2 in January and up to 11.8 × 10⁶ cm^?2 in July, with higher values over regions with high CCN concentrations and sufficient cloud coverage. Aerosols can reduce daily precipitation by up to 1.1 mm day^?1 in January and 19.4 mm day^?1 in July thus the wet removal rates over most of the land areas due to the formation of small CCNs, but they can increase precipitation over regions with the formation of large/giant CCN. These results indicate potential importance of the aerosol feedbacks and an urgent need for their accurate representations in current atmospheric models to reduce uncertainties associated with climate change predictions.     

The chemistry of bulk precipitation at a site in southeast england—II. Relationships between ions and comparison with other sites

This paper contains a statistical analysis of bulk precipitation chemistry of rain falling on the Tillingbourne Catchment, Surrey. Over the years 1978–1981, mean volume-weighted concentrations were: pH, 4.15, 70.8 μeq ℓ⁻¹ H⁺; organic, 2.8 mg ℓ⁻¹; total SO²⁻₄, 80.5 μeq ℓ⁻¹; NO⁻₃, 36.2 μeq ℓ⁻¹; NH⁺₄, 40.9 μeq ℓ⁻¹; Cl⁻ (2 years) 97.4 μeq ℓ⁻¹, rainfall 1067mm. Compared to other sites in the U.K. and elsewhere receiving acid precipitation in this pH is at the low end of the range, but levels of the other ions are moderate. Similar relations apply to deposition. Ion concentrations are highly correlated, especially total SO²⁻₄, NO⁻₃ and NH⁺₄. This group is linked more loosely to pH and organic content, while Cl⁻ does not correlate at all with the other ions, implying a totally different source, probably sea salt. H⁺ ions in rain correlate better with NO⁻₃ than with SO²⁻₄ and regression analysis suggests that almost all the NO⁻₃ is probably associated with nitric acid, whereas only about 57% of the SO²⁻₄ is associated with sulphuric acid. Deposition is approximately related to rainfall by a power law relationship in which the exponent of the equation varies between 0.5 and 0.9. However, it is concluded that an adequate estimate of deposition cannot be obtained from rainfall alone.     

Factor analysis of the MAP3S/RAINE precipitation chemistry network: 1976–1980

This paper presents a factor analysis of the MAP3S/RAINE precipitation chemistry data for the period 1976–1980. The purpose of the analysis is to determine the underlying source and/or processes accounting for the variance in the data. Three general sources, ‘acid,’ sea, and ‘ammonium/road dust/soil’ account for most of the variance in the data for the entire network for the aggregated three-and-one-half-year period. Both sulfate and nitrate are found to be significant components of the acid factor. Seasonal and spatial (individual site) analyses were able to distinguish other, less encompassing factors. Seasonal results showed a summer maximum in contribution for the acid factor, while individual site results showed that the contribution of the acid factor increases in going from the midwest to the northeast. Seasonal results show an ‘ammonium/soil’ factor appearing in spring and summer, while an ammonium sulfate factor appears in fall and winter. The results of this study should serve as a baseline for comparison with factor analyses of subsequent MAP3S data sets and factor analysis of other northeastern U.S. precipitation chemistry networks.     

Characteristics of precipitation chemistry at Lushan Mountain, East China: 1992–2009

Introduction

Trends in precipitation pH and conductivity during 1992?C2009, and in ionic compositions from January 2007 to June 2009, are reported from Lushan Mountain, one of the highest mountains in mid-east China. Annual mean pH was in the range of 4.35?C5.01 and showed a statistically very significant (P?P?Results and discussions Over the period of study, Lushan Mountain received more rainfall in spring and summer. The pH values varied seasonally with winter minima. The winter multiyear seasonal mean pH was 4.35. The corresponding summer value was 4.88. SO ₄ ^2? and NO ₃ ^? were the main anions, and NH ₄ ⁺ and Ca²⁺ the main cations. The anion to cation ratio was 0.8?C1.0, and that of [SO ₄ ^2? ] to [NO ₃ ^? ] was 2.4-3.0, much lower than that of the 1980s. However, sulfuric acid was still the main acid present. The ratio of [NH ₄ ⁺ ] to [Ca²⁺] was about 1.0, suggesting that these two alkaline substances provided close acid neutralizing capacity. The ratio of [Cl^?] to [Na⁺] was about 0.67, somewhat lower than that of natural precipitation.

Conclusions

Ionic composition varied seasonally and was closely correlated to the amounts of rainfall and pollution. Trajectory analyses showed that the trajectories to Lushan Mountain could be classified in six clusters and trajectories originating from the South Sea and the areas surrounding Lushan Mountain had the greatest impacts on precipitation chemistry.     

Summary of efficacy evaluations using aerially applied Gypchek® against gypsy moth in the U.S.A.

Abstract

Gypchek^®, the gypsy moth (Lymantria dispar L.) nucleopolyhedrosis virus product, is manufactured by the United States Department of Agriculture (USDA) Forest Service, and Animal and Plant Health Inspection Service under controlled conditions in a laboratory strain of gypsy moth larvae. Gypchek was registered with the U.S. Environmental Protection Agency in 1978 as a general use pesticide to control gypsy moth. This product has been the subject of intense research and development targeted toward maximizing efficacy while minimizing the cost of production and application. The current Gypchek tank mix is applied at 1.25 × 10¹²occlusion bodies (OB's) per hectare for each of two applications (3‐days apart) at 18.7 litres/ha per application.     

Statistical summary and analyses of event precipitation chemistry from the MAP3S network, 1976–1983

The MAP3S precipitation chemistry network base of event chemistry data includes nine sites widely distributed over the northeastern quadrant of the United States. Eight or these sites now have a period of record of at least 5 years. Four species (total sulfur, NO⁻₃, H⁺ and NH⁺₄) account for the bulk of ionic equivalents at seven inland sites; Ca²⁺ is nearly as important as NH⁺₄ at several of the inland sites, and sea salt species are major components at the two coastal sites. Average pH values (from arithmetic mean H⁺) range from 4.03 to 4.24 over the network. Time trend analyses for the period for sulfur and H⁺ show a consistent decrease, but the decrease is quite small and has low statistical significance; NO⁻₃; and NH⁺₄ show similar though less consistent trends. Significant seasonal trends (summer maximum, winter minimum) are found at most sites for sulfur and NH⁺₄; NO⁻₃ has a much weaker seasonal trend except at the coastal sites. Species pair correlations are strong among the four major ions, with the exception of correlations involving H⁺ at sites where crustal species are more important (Illinois, Ohio). Correlations can qualitatively be explained by common sources (crustal, sea-salt, anthropogenic), polluted vs nonpolluted events, and strong seasonal trends.     

Chemical composition of atmospheric precipitation in Czechoslovakia, 1976–1984—I. Monthly samples

The results of chemical analyses of monthly atmospheric precipitation samples from 12 stations within Czechoslovakia are presented. The sampling at the station with the longest record (Hrádek u Pacova, 80 km SE from Prague) covers 9 years. There is no clear regional pattern within the sampled territory, but a spring maximum was observed for most components. For SO₄⁻² and acidity a downward trend was indicated. Statistical analyses show that the important sources of mineralization of precipitation water are (in order of importance): coal combustion; sea spray; terrigenous dust; car exhaust; cement production; “European background” sulphur.     

Mobility and phytoavailability of Cu,Cr, Zn,and As in a contaminated soil at a wood preservation site after 4 years of aided phytostabilization

The remediation of copper-contaminated soils by aided phytostabilisation in 16 field plots at a wood preservation site was investigated. The mobility and bioavailability of four potentially toxic trace elements (PTTE), i.e., Cu, Zn, Cr, and As, were investigated in these soils 4 years after the incorporation of compost (OM, 5 % w/w) and dolomite limestone (DL, 0.2 % w/w), singly and in combination (OMDL), and the transplantation of mycorrhizal poplar and willows. Topsoil samples were collected in all field plots and potted in the laboratory. Total PTTE concentrations were determined in soil pore water (SPW) collected by Rhizon soil moisture samplers. Soil exposure intensity was assessed by Chelex100-DGT (diffusive gradient in thin films) probes. The PTTE phytoavailability was characterized by growing dwarf beans on potted soils and analyzing their foliar PTTE concentrations. OM and DL, singly and in combination (OMDL), were effective to decrease foliar Cu, Cr, Zn, and As concentrations of beans, the lowest values being numerically for the OM plants. The soil treatments did not reduce the Cu and Zn mineral masses of the bean primary leaves, but those of Cr and As decreased for the OM and DL plants. The Cu concentration in SPW was increased in the OM soil and remained unchanged in the DL and OMDL soils. The available Cu measured by DGT used to assess the soil exposure intensity correlated with the foliar Cu concentration. The Zn concentrations in SPW were reduced in the DL soil. All amendments increased As in the SPW. Based on DGT data, Cu availability was reduced in both OM and OMDL soils, while DL was the most effective to decrease soil Zn availability.     

An observational study of the HONO–NO2 coupling at an urban site in Guangzhou City,South China

The temporal behavior of HONO and NO₂ was investigated at an urban site in Guangzhou city, China, by means of a DOAS system during the Pearl River Delta 2006 intensive campaign from 10 to 24 July 2006. Within the whole measurement period, unexpected high HONO mixing ratios up to 2 ppb were observed even during the day. A nocturnal maximum concentration of about 8.43 ± 0.4 ppb was detected on the night of 24 July 2006. Combining the data simultaneously observed by different instruments, the coupling of HONO–NO₂ and the possible formation sources of HONO are discussed. During the measurement period, concentration ratios of HONO to NO₂ ranged from (0.03 ± 0.1) to (0.37 ± 0.09), which is significantly higher than previously reported values (0.01–0.1). Surprisingly, in most cases a strong daytime correlation between HONO and NO₂ was found, contrary to previous observations in China. Aerosol was found to have a minor impact on HONO formation during the whole measurement period. Using a pseudo steady state approach for interpreting the nocturnal conversion of NO₂ to HONO suggests a non-negligible role of the relative humidity for the heterogeneous HONO formation from NO₂.