Field investigations on the snow chemistry in central and southern california—II. Carbonyls and carboxylic acids

Snow samples from central and southern California were collected during the winter of 1987–1988 from there storms and analyzed for carbonyl compounds and carboxylic acids. Approximately 90% of the samples contained total aldehyde concentrations up to 40 μM. Formaldehyde and acetaldehyde were the dominant aldehydes observed; secondary aldehydes included glyoxal, methylglyoxal, and benzaldehyde. The highest aldehyde concentrations were observed in snow collected in areas where deciduous and coniferous forests are widespread. However, these aldehydes can be attributed also in part to primary and secondary products of anthropogenic activities. Formic and acetic were analyzed in all measured samples with concentrations ranging from 0.5 to 4.9 μM for HCOOH and from <0.3 to 13.4 μM for CH₃COOH. Maximum contribution of organic acids to precipitation-free acidity, calculated by assuming that the only sources of the measured formate and acetate were their respective acid forms, averaged 43.1% for samples with a pH⩽5. A consistent correlation between NH₄⁺ and acetate was found. [CH₃COOH] exceeded [HCOOH] in about 50% of the samples with the highest levels for CH₃COOH measured in cores collected from lower elevated locations adjacent to the Los Angeles basin. Results presented in this paper suggest that dry deposition and/or scavenging of carbonyl compounds and organic acids to snow may be important sinks for these compounds.     

Cluster analysis: A technique for estimating the synoptic meteorological controls on air and precipitation chemistry—Method and applications

Combining the pattern recognition capabilities of cluster analysis with isobaric air trajectory data is a useful way of quantifying the influence of synoptic meteorology on the pollution climatology at a site. A non-hierarchial clustering of 1000 mb isobaric trajectories, using squared Euclidean distance as a similarity measure, leads to the identification of a finite number of distinct synoptic patterns. Typical airbore and aqueous pollutant concentrations associated with each of these patterns may then be established. By considering 3-day air trajectories in this study, the “history” of an air parcel is captured in an improved manner, when compared with attempts to use individual day weather “types” to characterize meterological situations.     

Major ion chemistry and control of weathering of Bhimtal Lake, Humaun Himalaya, India

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Characteristics of phosphorus chemistry and its geographical distribution in the Haihe River valley,North China

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Trends in particulate deposition and precipitation chemistry at Leeds (U.K.) 1907–1987

A review of the available data on the composition of precipitation and the deposition rates of various species has been carried out for the city of Leeds in Northern England covering the years 1907–1987. The information for three typical sites representing heavily industrialized, suburban and rural locations is compared. The exceptionally high deposition rates and large urban/rural differences of the early years have now disappeared. Perhaps surprisingly, the parameter which has changed least is the net acidity. The highly acidic deposits of sulphates and chlorides from coal combustion before 1930 were counterbalanced by correspondingly high deposition rates of ammonia and alkaline dusts. The only major parameter which shows a significant increase in nitrate.     

Response of “Alamo” switchgrass tissue chemistry and biomass to nitrogen fertilization in West Tennessee,USA

Switchgrass (Panicum virgatum) is a perennial, warm-season grass that has been identified as a potential biofuel feedstock over a large part of North America. We examined above- and belowground responses to nitrogen fertilization in “Alamo” switchgrass grown in West Tennessee, USA. The fertilizer study included a spring and fall sampling of 5-year old switchgrass grown under annual applications of 0, 67, and 202 kg N ha^?1 (as ammonium nitrate). Fertilization changed switchgrass biomass allocation as indicated by root:shoot ratios. End-of-growing season root:shoot ratios (mean ± SE) declined significantly (P ≤ 0.05) at the highest fertilizer nitrogen treatment (2.16 ± 0.08, 2.02 ± 0.18, and 0.88 ± 0.14, respectively, at 0, 67, and 202 kg N ha^?1). Fertilization also significantly increased above- and belowground nitrogen concentrations and decreased plant C:N ratios. Data are presented for coarse live roots, fine live roots, coarse dead roots, fine dead roots, and rhizomes. At the end of the growing season, there was more carbon and nitrogen stored in belowground biomass than aboveground biomass. Fertilization impacted switchgrass tissue chemistry and biomass allocation in ways that potentially impact soil carbon cycle processes and soil carbon storage.     

Chemical characteristics of long-term acid rain and its impact on lake water chemistry:A case study in Southwest China

The chemical composition of acid rain and its impact on lake water chemistry in Chongqing,China,from 2000 to 2020 were studied in this study.The regional acid rain intensity is affected jointly by the acid gas emissions and the neutralization of alkaline substances.The pH of precipitation experienced three stages of fluctuating decline,continuous improvement,and a slight correction.Precipitation pH showed inflection points in 2010,mainly due to the total control actions of SO₂and NO     

A statistical intercomparison between “urban” and “rural” precipitation chemistry data from greater Manchester and two nearby secondary national network sites in the United Kingdom

Precipitation chemistry data from a dense urban monitoring network in Greater Manchester, northwest England, were compared with interpolated values from the U.K. secondary national acid deposition monitoring network for the year 1988. Differences were found to be small. However, when data from individual sites from the Greater Manchester network were compared with data from the two nearest secondary national network sites, significant differences were found using simple and complex statistical analyses. Precipitation chemistry at rural sites could be similar to that at urban sites, but the sources of some ions were thought to be different. The synoptic-scale gradients of precipitation chemistry, as shown by the secondary national network, also accounted for some of the differences.     

Recent developments of surface complexation models applied to environmental aquatic chemistry

1　ＢａｃｋｇｒｏｕｎｄＩｎｇｅｏｃｈｅｍｉｃａｌｃｉｒｃｕｌａｔｉｏｎ ,ｖａｒｉｏｕｓｐｏｌｌｕｔａｎｔｓｗｉｔｈａｄｖｅｒｓｅｉｍｐａｃｔｓ (ｅ .ｇ .,ｔｏｘｉｃｉｔｙ ,ｍｕｔａｇｅｎｉｃｉｔｙａｎｄｌｅｔｈａｌｉｔｙ)ａｒｅｕｓｕａｌｌｙａｓｓｏｃｉａｔｅｄｗｉｔｈｈｅｔｅｒｏｇｅｎｅｏｕｓｐａｒｔｉｃｌｅｓ,ｐｒｅｄｏｍｉｎａｎｔｌｙｃｌａｙｍｉｎｅｒａｌｓ .Ｇｅｎｅｒａｌｌｙ ,ｔｈｅｐｒｏｐｅｒｔｉｅｓｏｆｔｈｅｓｅｃｏｍｐｌｅｘｐａｒｔｉｃｌｅｓｓｈｏｕｌｄｂｅｄｅｓｃｒｉｂｅｄｕｓｉｎ…     

Sex pheromone chemistry and field trapping studies of the elm spanworm Ennomos subsignaria (Hübner) (Lepidoptera:Geometridae)

The elm spanworm, Ennomos subsignaria (Hübner), occurs throughout Canada and the eastern United States and can be a destructive forest pest on a wide range of deciduous trees. Gas chromatography/mass spectrometry (GC/MS) and coupled gas chromatographic–electroantennographic detection (GC/EAD) analysis of pheromone gland extracts, in combination with chemical synthesis and field trapping studies have identified (2S, 3R)-2-((Z)-oct-2′-enyl)-3-nonyl oxirane (hereafter Z6-9S, 10R-epoxy-19:H) as the female-produced sex pheromone. Significantly more male moths were captured between 1–100 μg loadings of this compound on red rubber septa in sticky traps compared to blank (unbaited) traps; catches then declined at higher dosages (500–1000 μg). The other isomeric enantiomer, (2R, 3S)-2-[(Z)-oct-2′-enyl]-3-nonyl oxirane (Z6-9R, 10S-epoxy-19:H), at a 10-μg dosage did not elicit trap capture. The likely precursor to the active epoxide, (Z, Z)-6, 9-nonadecadiene ((Z, Z)-6, 9-19:H), identified in virgin female sex pheromone glands, did not elicit trap capture either, and inhibited trap capture when combined with the active epoxide. Racemic 2-((Z)-oct-2′-enyl)-3-nonyl oxirane showed no significant difference in trap capture compared with Z6-9S, 10R-epoxy-19:H, indicating that the opposite enantiomer was not antagonistic. The addition of the EAD-active diene epoxide enantiomers (2S, 3R)-2-[(Z, Z)-octa-2′, 5′-dienyl]-3-nonyl oxirane or (2R, 3S)-2-[(Z, Z)-octa-2′, 5′-dienyl]-3-nonyl oxirane in admixture with Z6-9S, 10R-epoxy-19:H (at 10% of the latter) did not enhance or decrease trap capture compared to Z6-9S, 10R-epoxy-19:H oxirane alone, so they are not likely pheromone components. This pheromone, impregnated in rubber septa at less than 100-μg dosage, can now be used as a trap bait to develop detection and monitoring strategies for this insect.     

Cluster analysis: A technique for estimating the synoptic meteorological controls on air and precipitation chemistry—Results from Eskdalemuir,South Scotland

Clustering of isobaric trajectories arriving at Eskdalemuir, south Scotland, enabled us to isolate the influences of atmospheric transport patterns and precipitation amount on gas, aerosol and precipitation chemistry at this site. We conclude that at Eskdalemuir, 55% of the variation in summer season non-sea-salt sulphate concentration in rain may be explained by upwind history defined by trajectory clustering and by precipitation amount. Each cluster of trajectories could be described by distinct synoptic weather conditions, leading to the interesting prospect of assigning a typical ion concentration in precipitation to a given synoptic weather pattern. The scale of the synoptic patterns identified in this study were shown to be able to explain the variation in sulphur dioxide concentrations observed across a network of 50 stations contributing to the European Monitoring and Evaluation Programme.There is greater confidence in Global Climate Model simulations of future circulation patterns as a result of climate change than of equivalent simulations of temperature and precipitation distributions. A first approximation of future levels of ion deposition may therefore best be inferred from circulation pattern-ion concentration relationships of the type developed in this paper. The influence of other less certain changes in precipitation type/amount, scavenging processes and emission levels should then be assessed against a background of changes in the frequency of circulation patterns.     

Multiphase chemistry in a microphysical radiation fog model—A numerical study

A microphysical radiation fog model is coupled with a detailed chemistry module to simulate chemical reactions in the gas phase and in fog water during a radiation fog event. In the chemical part of the model the microphysical particle spectrum is subdivided into three size classes corresponding to non-activated aerosol particles, small and large fog droplets. Chemical reactions in the liquid phase are separately calculated in the small and in the large droplet size class. The impact of the chemical constitution of activated aerosols on fogwater chemistry is considered in the model simulations. The mass transfer of chemical species between the gas phase and the two liquid phases is treated in detail by solving the corresponding coupled differential equation system. The model also accounts for concentration changes of gas-phase and aqueous-phase chemical species which are induced by turbulence, gravitational settling and by evaporation/condensation processes.Numerical results demonstrate that fogwater chemistry is strongly controlled by dynamic processes, i.e. the vertical growth of the fog, turbulent mixing processes and the gravitational settling of the particles. The concentrations of aqueous-phase chemical species are different in the two droplet size classes. Reactands with lower water solubility are mainly found in the large droplet size class because the characteristic time for their mass transfer from the gas phase into the liquid phase is essentially longer than the characteristic time for the formation of large fog droplets. Species with high water solubility are rapidly transferred into the small fog droplets and are then washed out by wet deposition before these particles grow further to form large droplets. Thus, the concentrations of the major ions (NO₃⁻, NH₄⁺) are much higher in small than in large droplets, yielding distinctly lower pH values of the small particles. In the present study the reaction of sulfur with H₂O₂ and the Fe(III)-catalysed autoxidation of S(IV) are the major S(VI) producing mechanisms in fog water. Most of the time the sulfur oxidation rates are higher in the large than in the small droplets. Fogwater deposition by gravitational settling occurs mainly in the large droplet size class. However, since in the small droplets the concentrations of chemical species with very good water solubility are relatively high, in both droplet size classes the total wet deposition of these reactands is of the same order of magnitude.     

Major element chemistry, δ2H, δ18O and 87Sr/86Sr in a snow profile across central Scandinavia

In late February 1988, fresh snow was sampled at eight stations along a 450 km long transect, spanning the Scandinavian Peninsula from the Atlantic Ocean in the west to the Gulf of Bothnia in the east. The elements Na, Mg, Ca, S, Cl, Sr, Al, Fe, Mn and Zn were analyzed, and the nuclide pairs ⁸⁷Sr⁸⁶Sr, ¹⁸O¹⁶O and ²H¹H measured.The concentrations of Na, Mg, Cl and Sr decrease rapidly with distance from the Atlantic coast. The other elements studied reflect more complicated patterns, caused by addition of terrigeneous matter and anthropogenic pollution.Stable oxygen and hydrogen isotopic compositions follow the general precipitation pattern, with values close to seawater in the west, becoming isotopically progressively lighter eastwards.The ⁸⁷Sr/⁸⁶Sr ratio in snow varies from 0.7098 near the Atlantic Ocean to 0.7194 at the easternmost station. Mixing calculations reveal that seawater contributes about 90% of the Sr at the westernmost stations, decreasing to 10–30% some 300 km eastwards. The increase in the ⁸⁷Sr/⁸⁶Sr ratio inland is controlled by Sr fractions more radiogenic than seawater, but strongly heterogeneous. The easternmost station is distinctly influenced by pollution, giving enhanched concentrations of S, Ca and Sr and the highest ⁸⁷Sr/⁸⁶Sr ratio.     

Effects of solution chemistry on arsenic(Ⅴ) removal by low-cost adsorbents

Natural and anthropogenic arsenic （As） contamination of water sources pose serious health concerns, especially for small communities in rural areas. This study assessed the applicability of three industrial byproducts （coal fly ash, lignite, and green waste compost） as the low-cost adsorbents for As（V） removal under various field-relevant conditions （dissolved oxygen, As（V）/Fe ratio, solution pH, and presence of competing species）. The physico-chemical properties of the adsorbents were characterized by XRD, XRF, FT-IR, and NMR analysis. Batch experiments demonstrated that coal fly ash could provide effective As（V） removal （82.1%-95%） because it contained high content of amorphous iron/aluminium hydroxides for As（V） adsorption and dissolvable calcium minerals for calcium arsenate precipitation. However, the addition of lignite and green waste compost was found unfavourable since they hindered the As（V） removal by 10%-42% possibly due to dissolution of organic matter and ternary arsenate-iron-organic matter complexes. On the other hand, higher concentrations of dissolved iron （comparing As（V）/Fe ratios of 1：1 and 1：10） and dissolved oxygen （comparing 0.2 and 6 mg/L） only marginally enhanced the As（V） removal at pH 6 and 8. Thus, addition of dissolved iron, water aeration, or pH adjustment became unnecessary because coal fly ash was able to provide effective As（V） removal under the natural range of geochemical conditions. Moreover, the presence of low levels of background competing （0.8 or 8 mg/L of humic acid, phosphate, and silicate） imposed little influence on As（V） removal, possibly because the high adsorption capacity of coal fly ash was far from exhaustion. These results suggested that coal fly ash was a potentially promising adsorbent that warranted further investigation.     

Influence of Indian mustard （Brassicajuncea） on rhizosphere soil solution chemistry in long-term contaminated soils： A rhizobox study

This study investigated the influence of Indian mustard (Brassica juncea) root exudation on soil solution properties (pH, dissolved organic carbon (DOC), metal solubility) in the rhizosphere using a rhizobox. Measurement was conducted following the cultivation of Indian mustard in the rhizobox filled four di erent types of heavy metal contaminated soils (two alkaline soils and two acidic soils). The growth of Indian mustard resulted in a significant increase (by 0.6 pH units) in rhizosphere soil solution pH of acidic soils and only a slight increase (< 0.1 pH units) in alkaline soils. Furthermore, the DOC concentration increased by 17–156 mg/L in the rhizosphere regardless of soil type and the extent of contamination, demonstrating the exudation of DOC from root. Ion chromatographic determination showed a marked increase in the total dissolved organic acids (OAs) in rhizosphere. While root exudates were observed in all soils, the amount of DOC and OAs in soil solution varied considerably amongst di erent soils, resulting in significant changes to soil solution metals in the rhizosphere. For example, the soil solution Cd, Cu, Pb, and Zn concentrations increased in the rhizosphere of alkaline soils compared to bulk soil following plant cultivation. In contrast, the soluble concentrations of Cd, Pb, and Zn in acidic soils decreased in rhizosphere soil when compared to bulk soils. Besides the influence of pH and DOC on metal solubility, the increase of heavy metal concentration having high stability constant such as Cu and Pb resulted in a release of Cd and Zn from solid phase to liquid phase.     

Three industries and wastewater and COD discharge of Beijing

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Trends and characteristics of total ozone’and vertical profile in Kunming and Beijing，China

This paper presents the trends of total ozone at Beijing and Kunming areas during the period of 1979 to 1989．The SBUV ozone vertical profile data and the periodic oscillation in upper ozone layers over Beijing area are also described．The results show that the variation of Beijing and Kunming per decade are about-5%and-1.5%．respectively．     

Chemical behavior and risk assessment of four pesticidesin soil and water

ＣｈｅｍｉｃａｌｂｅｈａｖｉｏｒａｎｄｒｉｓｋａｓｓｅｓｓｍｅｎｔｏｆｆｏｕｒｐｅｓｔｉｃｉｄｅｓｉｎｓｏｉｌａｎｄｗａｔｅｒＪｉａｎｇＸｉｌｉｕ；ＨｕａＸｉａｏｍｅｉ（ＮａｎｊｉｎｇＩｎｓｔｉｔｕｔｅｏｆＥｎｖｉｒｏｎｒｎｅｎｔＳｃｉｅｎｃｅ，Ｎａ...     

β-Cyclodextrin and its derivatives-enhanced solubility and biodegradation of 2-nitrobiphenyl

This paper investigated the effects of β-cyclodextrins （I3-CD） and its two derivatives, hydroxypropyl-β-cyclodextrin （HPCD） and carboxymethyl-β-cyclodextrin （CMCD）, on the solubility and biodegradation of 2-nitrophenyl by an A cinetbacter sp. Results showed that β-CD, HPCD and CMCD could not be utilized by A cinetbacter sp. as sole carbon source and none of the CDs had toxic effects on the growth of the bacteria in the experiments; all the CDs could enhance the apparent solubility and accelerate the biodegradation of 2-nitrobipheny. It showed that biodegradation-accelerating effects of CDs on 2-nitrobiphenyl were correlated with their solubility-enhancing effects. Among three CDs investigated, CMCD had the most obvious effects both on the apparent solubility and the biodegradation, followed by β-CD and HPCD.     

Methylated and thiolated arsenic species for environmental and health research——A review on synthesis and characterization

Hundreds of millions of people around the world are exposed to elevated concentrations of inorganic and organic arsenic compounds, increasing the risk of a wide range of health effects. Studies of the environmental fate and human health effects of arsenic require authentic arsenic compounds. We summarize here the synthesis and characterization of more than a dozen methylated and thiolated arsenic compounds that are not commercially available. We discuss the methods of synthesis for the following14 trivalent(Ⅲ) and pentavalent() arsenic compounds: monomethylarsonous acid(MMA~Ⅲ), dicysteinylmethyldithioarsenite(MMA~Ⅲ(Cys)_2), monomethylarsonic acid(MMA~Ⅴ),monomethylmonothioarsonic acid(MMMTAⅤ) or monothio-MMA~Ⅴ, monomethyldithioarsonic acid(MMDTA~Ⅴ) or dithio-MMA~Ⅴ, monomethyltrithioarsonate(MMTTA~Ⅴ) or trithio-MMA~Ⅴ,dimethylarsinous acid(DMA~Ⅲ), dimethylarsino-glutathione(DMA~Ⅲ(SG)), dimethylarsinic acid(DMA~Ⅴ), dimethylmonothioarsinic acid(DMMTA~Ⅴ) or monothio-DMAⅤ, dimethyldithioarsinic acid(DMDTA~Ⅴ) or dithio-DMA~Ⅴ, trimethylarsine oxide(TMAO~Ⅴ), arsenobetaine(AsB), and an arsenicin-A model compound. We have reviewed and compared the available methods,synthesized the arsenic compounds in our laboratories, and provided characterization information. On the basis of reaction yield, ease of synthesis and purification of product, safety considerations, and our experience, we recommend a method for the synthesis of each of these arsenic compounds.