“The Kesterson effect”

Hypothesized to be derived from Cretaceous marine sedimentary rocks, selenium contamination of the Kesterson National Wildlife Refuge is traced through irrigation drainage to the source bedrock of the California Coast Ranges. This biogeochemical pathway of selenium is defined here as the “Kesterson effect.” At the refuge ponds, this effect culminated in 1983 in a 64% rate of deformity and death of embryos and hatchlings of wild aquatic birds. From the previous companion paper on irrigation drainage, the Kesterson effect has been implicated in nine of 11 reconnaissance areas studied in the western United States. Deformities have resulted in at least five of these sites. Climatic, geologic, hydrologic, and soil conditions in these reconnaissance areas are similar to those in the area surrounding Kesterson National Wildlife Refuge in the west-central San Joaquin Valley of California. In California, selenium, as selenate, was ultimately found weathered with sulfur from marine sources in soluble sodium and magnesium sulfate salts, which are concentrated by evaporation on farmland soils. The Se, mobilized by irrigation drainage, is bioaccumulated to toxic levels in refuge wetland ponds that are located mainly in hydrologically closed basins and thus act as concentrating disposal points. The depositional environment of the ponds may be similar to that of the nutrient-rich continental shelf edge and slope in which Cretaceous, Eocene, and Miocene sediments found to be seleniferous in the California Coast Ranges were deposited. Bioaccumulation may be therefore a primary mechanism of selenium enrichment in ancient sediments in addition to that of the formerly suggested Cretaceous volcanic pathway.     

荧光法测定微量硫酸盐的研究

研究了钪与桑色素形成的络合物在紫外光照射下产生淡绿色荧光,受硫酸根的影响而减弱,其荧光强度的降低量与硫酸根浓度成线性关系,据此建立了一个简便测定微量硫酸根的方法,适宜的测定范围为0～1.6mg/L SO_4~(2-),文中还研究了某些阳离子和阴离子的干扰影响及其消除,最后将本法应用于地热水、自来水、泉水、海水和一些分析纯化学试剂中微量硫酸盐的测定,方法灵敏、简便、快速,结果满意。     

硫酸铝废渣生产硅酸钠的研究

讨论以硫酸铝废渣经水洗，碱萃取生产硅酸钠的最佳工艺条件，所得硅酸钠产品，符合国家规定．本生产工艺不仅解决了环保问题，还综合利用了资源，具有可观的经济效益．     

废气中硫含量分析方法的试验研究

通过试验研究,建立了高氯酸常压消解-离子色谱法测定工业废气中硫含量的分析方法。滤筒采集污染源废气颗粒物,利用高氯酸常压消解,将元素硫氧化为硫酸根,利用离子色谱法测定,进而得出硫的含量。结果表明：此方法简单、灵敏、检出限低。     

pH dependence of persulfate activation by EDTA/Fe(III) for degradation of trichloroethylene

The ability of free ferrous ion activated persulfate (S₂O₈²⁻) to generate sulfate radicals (SO₄⁻) for the oxidation of trichloroethylene (TCE) is limited by the scavenging of SO₄⁻ with excess Fe²⁺ and a quick conversion of Fe²⁺ to Fe³⁺. This study investigated the applicability of ethylene-diamine-tetra-acetic acid (EDTA) chelated Fe³⁺ in activating persulfate for the destruction of TCE in aqueous phase under pH 3, 7 and 10. Fe³⁺ and EDTA alone did not appreciably degrade persulfate. The presence of TCE in the EDTA/Fe³⁺ activated persulfate system can induce faster persulfate and EDTA degradation due to iron recycling to activate persulfate under a higher pH condition. Increasing the pH leads to increases in pseudo-first-order-rate constants for TCE, S₂O₈²⁻ and EDTA degradations, and Cl generation. Accordingly, the experiments at pH 10 with different EDTA/Fe³⁺ molar ratios indicated that a 1/1 ratio resulted in a remarkably higher degradation rate at the early stage of reaction as compared to results by other ratios. Higher persulfate dosage under the EDTA/Fe³⁺ molar ratio of 1/1 resulted in greater TCE degradation rates. However, increases in persulfate concentration may also lead to an increase in the rate of persulfate consumption.     

Formation of secondary inorganic aerosols by power plant emissions exhausted through cooling towers in Saxony

Background, aim, and scope  The fraction of ambient PM₁₀ that is due to the formation of secondary inorganic particulate sulfate and nitrate from the emissions of two large, brown-coal-fired power stations in Saxony (East Germany) is examined. The power stations are equipped with natural-draft cooling towers. The flue gases are directly piped into the cooling towers, thereby receiving an additionally intensified uplift. The exhausted gas-steam mixture contains the gases CO, CO₂, NO, NO₂, and SO₂, the directly emitted primary particles, and additionally, an excess of ‘free’ sulfate ions in water solution, which, after the desulfurization steps, remain non-neutralized by cations. The precursor gases NO₂ and SO₂ are capable of forming nitric and sulfuric acid by several pathways. The acids can be neutralized by ammonia and generate secondary particulate matter by heterogeneous condensation on preexisting particles. Materials and methods  The simulations are performed by a nested and multi-scale application of the online-coupled model system LM-MUSCAT. The Local Model (LM; recently renamed as COSMO) of the German Weather Service performs the meteorological processes, while the Multi-scale Atmospheric Transport Model (MUSCAT) includes the transport, the gas phase chemistry, as well as the aerosol chemistry (thermodynamic ammonium–sulfate–nitrate–water system). The highest horizontal resolution in the inner region of Saxony is 0.7 km. One summer and one winter episode, each realizing 5 weeks of the year 2002, are simulated twice, with the cooling tower emissions switched on and off, respectively. This procedure serves to identify the direct and indirect influences of the single plumes on the formation and distribution of the secondary inorganic aerosols. Results and conclusions  Surface traces of the individual tower plumes can be located and distinguished, especially in the well-mixed boundary layer in daytime. At night, the plumes are decoupled from the surface. In no case does the resulting contribution of the cooling tower emissions to PM₁₀ significantly exceed 15 μgm⁻³ at the surface. These extreme values are obtained in narrow plumes on intensive summer conditions, whereas different situations with lower turbulence (night, winter) remain below this value. About 90% of the PM₁₀ concentrations in the plumes are secondarily formed sulfate, mainly ammonium sulfate, and about 10% originate from the primarily emitted particles. Under the assumptions made, ammonium nitrate plays a rather marginal role. Recommendations and perspectives  The analyzed results depend on the specific emission data of power plants with flue gas emissions piped through the cooling towers. The emitted fraction of ‘free’ sulfate ions remaining in excess after the desulfurization steps plays an important role at the formation of secondary aerosols and therefore has to be measured carefully.     

Degradation of acetic acid with sulfate radical generated by persulfate ions photolysis

The photolysis of was studied for the removal of acetic acid in aqueous solution and compared with the H₂O₂/UV system. The radicals generated from the UV irradiation of ions yield a greater mineralization of acetic acid than the OH radicals. Acetic acid is oxidized by radicals without significant formation of intermediate by-products. Increasing system pH results in the formation of OH radicals from radicals. Maximum acetic acid degradation occurred at pH 5. The results suggest that above this pH, competitive reactions with the carbon mineralized inhibit the reaction of the solute with and also OH radicals. Scavenging effects of two naturally occurring ions were tested; in contrast to ions, the presence of Cl⁻ ions enhances the efficiency of the /UV process towards the acetate removal. It is attributed to the formation of the Cl radical and its great reactivity towards acetate.     

气相分子吸收光谱法测定废水中硫化物

应用分子吸收光谱地不同行业废水中的硫化物进行了测定。当水样不含干扰物质时可直接测定,否则需经沉淀、过滤、洗涤前处理。进行一与碘量法和吹气－对氨基二甲基苯胺光度法的对比试验,所测结果较为一致。分子吸收光谱法的线性范围为０．１ｍｇ／Ｌ￣４．０ｍｇ／Ｌ。取５ｍＬ样品直接测定,检测限为０．０５ｍｇ／Ｌ;取５ｍＬ样品沉淀等有处理后,检测限为０．００５ｍｇ／Ｌ。测定速度快,直接测定最多２ｍｉｎ即可测一个样品;     

Determination of Water-soluble Atmospheric Aerosols Using Ion Chromatography

A field study was established to investigate the chemical composition of atmospheric aerosols in Chicago, IL. One goal of this study was to determine the influence of precursor trace gases and local meteorology on concentrations of secondary aerosol ionic species. This paper describes the method details, shows the method is analytically valid, and reports overall as well as some specific results found during the field study. Two particulate air samples were collected per day onto quartz fiber filters at the Loyola University Chicago Air Station during the summer months in 2002–2004. In parallel, mixing ratios of ozone and nitrogen oxides were monitored and weather parameters were recorded. Particulates were extracted from the filter substrates and the subsequent solutions were analyzed by ion chromatography for anions, including low molecular weight organic acids, and cations. A washing procedure was implemented to reduce the high background values of the quartz fiber filters. Method validation showed that the collection method was efficient for all ions with exception of nitrate, whose efficiency of 70% indicated losses caused by volatilization. The extraction method also proved efficient for both field and laboratory samples, and the repeatability of the method was high with relative standard deviations less than 10% for all ions. Reproducibility of the results was determined by comparison of sulfate to sulfur analyzed by total reflection X-ray fluorescence spectrometry and proved to be high as well. Concentrations differed significantly between the three summer studies due to varying levels of precursor species as a consequence of distinct temperatures and wind direction profiles.     

Uranium removal from groundwater via in situ biostimulation: Field-scale modeling of transport and biological processes

During 2002 and 2003, bioremediation experiments in the unconfined aquifer of the Old Rifle UMTRA field site in western Colorado provided evidence for the immobilization of hexavalent uranium in groundwater by iron-reducing Geobacter sp. stimulated by acetate amendment. As the bioavailable Fe(III) terminal electron acceptor was depleted in the zone just downgradient of the acetate injection gallery, sulfate-reducing organisms came to dominate the microbial community. In the present study, we use multicomponent reactive transport modeling to analyze data from the 2002 field experiment to identify the dominant transport and biological processes controlling uranium mobility during biostimulation, and determine field-scale parameters for these modeled processes. The coupled process simulation approach was able to establish a quantitative characterization of the principal flow, transport, and reaction processes based on the 2002 field experiment, that could be applied without modification to describe the 2003 field experiment. Insights gained from this analysis include field-scale estimates of the bioavailable Fe(III) mineral threshold for the onset of sulfate reduction, and rates for the Fe(III), U(VI), and sulfate terminal electron accepting processes.