Chemical characteristics of precipitation at metropolitan Newark in the US East Coast

To investigate the chemical characteristics of precipitation in the polluted coastal atmosphere, a total of 46 event-based precipitation samples were collected using a wet-only automatic precipitation collector from September 2006 to October 2007 at metropolitan Newark, New Jersey in the US East Coast. Samples were analyzed by ion chromatography for the concentrations of major inorganic ions (Cl⁻, NO₃⁻, SO₄²⁻, F⁻, NH₄⁺, Ca²⁺, Mg²⁺, Na⁺, K⁺) and organic acid species (CH₃COO⁻, HCOO⁻, CH₂(COO)₂²⁻, C₂O₄²⁻). Selected trace metals (Sb, Pb, Al, V, Fe, Cr, Co, Ni, Cu, Zn, Cd) in samples were determined by ICPMS. Mass concentration results show that SO₄²⁻ was the most dominant anion accounting for 51% of the total anions, controlling the acidity of the precipitation. NH₄⁺ accounted for 48.6% of the total cations, dominating the precipitation neutralization. CH₃COO⁻ and HCOO⁻ were the two dominant water-soluble organic acid species, accounting for 42% and 40% of the total organic acids analyzed, respectively. Al, Zn and Fe were the three major trace metals in precipitation, accounting for 34%, 27%, and 25% of the total mass of metals analyzed. The pH values in precipitation ranged from 4.4 to 4.9, indicating an acidic nature. Enrichment Factor (EF) Analysis showed that Na⁺, Cl⁻, Mg²⁺ and K⁺ in the precipitation were primarily of marine origin, while most of the Fe, Co and Al were from crust sources. Pb, V, Cr, Ni were moderately enriched with EFs ranging 43–410, while Zn, Sb, Cu, Cd and F⁻ were highly enriched with EFs > 700, indicating significant anthropogenic influences. Factor analysis suggests 6 major sources contributing to the observed composition of precipitation at this location: (1) nitrogen-enriched soil, (2) secondary pollution processes, (3) marine sources, (4) incinerations, (5) oil combustions, and (6) malonate–vanadium enriched sources. To further explore the source–precipitation event relationships and seasonality, cluster analysis was performed for all precipitation events. Results show that about half of the precipitation events were characterized by mixed sources. Significant influences of nitrogen-enriched soil and marine sources were associated with precipitation events in spring and autumn, while secondary pollution processes, incineration and oil combustion contributed greatly in summer.     

Impact of acid mine drainages on surficial waters of an abandoned mining site

Weathering of sulphide minerals produces a great variety of efflorescences of soluble sulphate salts. These minerals play an important role for environmental pollution, since they can be either a sink or a source for acidity and trace elements. This paper aims to characterise surface waters affected by mining activities in the Sierra Minera of Cartagena-La Union (SE, Spain). Water samples were analysed for trace metals (Zn, Cd, Pb, Cu, As and Fe), major ions (Na⁺, K⁺, Ca²⁺ and Mg²⁺) and anions (F^?, Cl^?, NO₃ ^?, CO₃ ^2?, SO₄ ^2?) concentrations and were submitted to an “evaporation-precipitation” experiment that consisted in identifying the salts resulting from the evaporation of the water aliquots sampled onsite. Mineralogy of the salts was studied using X-ray diffraction and compared with the results of calculations using VISUAL MINTEQ. The study area is heavily polluted as a result of historical mining and processing activities that has produced large amount of wastes characterised by a high trace elements content, acidic pH and containing minerals resulting from the supergene alteration of the raw materials. The mineralogical study of the efflorescences obtained from waters shows that magnesium, zinc, iron and aluminium sulphates predominate in the acid mine drainage precipitates. Minerals of the hexahydrite group have been quantified together with minerals of the rozenite group, alunogen and other phases such as coquimbite and copiapite. Calcium sulphates correspond exclusively to gypsum. In a semiarid climate, such as that of the study area, these minerals contribute to understand the response of the system to episodic rainfall events. MINTEQ model could be used for the analysis of waters affected by mining activities but simulation of evaporation gives more realistic results considering that MINTEQ does not consider soluble hydrated salts.     

Competitive biosorption of lead, cadmium, copper, and arsenic ions using algae

The present study aims to evaluate the competitive biosorption of lead, cadmium, copper, and arsenic ions by using native algae. A series of experiments were carried out in a batch reactor to obtain equilibrium data for adsorption of single, binary, ternary, and quaternary metal solutions. The biosorption of these metals is based on ion exchange mechanism accompanied by the release of light metals such as calcium, magnesium, and sodium. Experimental parameters such as pH, initial metal concentrations, and temperature were studied. The optimum pH found for removal were 5 for Cd²⁺ and As³⁺ and 3 and 4 for Pb²⁺ and Cu²⁺, respectively. Fourier transformation infrared spectroscopy analysis was used to find the effects of functional groups of algae in biosorption process. The results showed that Pb²⁺ made a greater change in the functional groups of algal biomass due to high affinity to this metal. An ion exchange model was found suitable for describing the biosorption process. The affinity constants sequence calculated for single system was K _Pb > K _Cu > K _Cd > K _As; these values reduced in binary, ternary, and quaternary systems. In addition, the experimental data showed that the biosorption of the four metals fitted well the pseudo-second-order kinetics model.     

Flexibility of X-Ray Emission Spectrography as Adapted to Microanalysis of Air Pollutants

Methods previously published by this laboratory for analyzing thin dust coatings of airborne particulates have been further evaluated, as applied to vast air pollution surveys. It was demonstrated that choice of glass fiber filters adapted to high-volume samplers restricts the analysis to a limited number of elements, such as lead. More flexibility and versatility are attained through the use of organic membrane filters mounted in small plastic monitors which permit multi-elemental analysis at least as accurately as with other popular but time-consuming techniques. These qualities of speed and accuracy allow shorter intervals of sampling which are normally required for better statistical assessment of broad air pollution surveys. Sensitivity of the technique reaches a value close to 0.05 μg/m³, while time of analysis required is about five minutes per element after receipt of the sample.     

Influence of a slight urban pollution on the size distribution of a marine aerosol

Size measurements of atmospheric aerosol, using impactors and Nuclepore filters have been carried out. Analysis were made by electron and optic microscopy. Thus we obtain a size distribution from D_p = 10^?2μm to D_p = 70 μm over the Atlantic Ocean and at urban location. The statistical analysis of the curves allows to compare the results and to point out the effect of an urban pollution on a marine aerosol.     

Assessment of transboundary mass fluxes of air pollutants by aircraft measurements: A preliminary survey with reference to a case study

A technique has been employed by which transboundary mass fluxes of SO², SO₄²⁻, NO_x, NO₃⁻, and O₃ are assessed. As an example the results of one measuring flight are presented. This flight was carried out along the eastern and western border of the Netherlands. An uncertainty analysis yields that the accuracy of calculated transboundary mass fluxes is most dependent on the accuracy of the values for the depth of the mixing layer and the wind velocity. Mass fluxes calculated in this case study appear to be accurate within ± 55 %, apart from inaccuracies due to non-representativity of concentration and wind data with respect to the mixing layer. On the basis of the uncertainty analysis, recommendations for further improvement of the method are made so that a reduction of this ± 55 % to ± 20 % can be achieved. Finally, conclusions about the origin of the observed pollution are drawn.     

An evaluation of artifact SO42− formation on nylon filters under field conditions

The extent of SO₂ conversion on Membrana (Ghia) Nylasorb nylon filters under field conditions has been evaluated and found to be quite variable. The S-SO₄²⁻ loading on the nylon filters is higher at higher SO₂ concentrations, and on a long term basis approaches a saturatio limit of 2.5 μg S-SO₄²⁻ on a 47mm disc, at a dosage of 230 μg SO₂ approximately. The % conversion decreases as the SO₂ concentration increases. On a long term basis, at an SO₂ concentration range of 1.0–7.7 μg m⁻³, the conversion ranges from 8.2% to 2.1%. The dependence of SO₂ conversion on nylon filters on relative humidity displays a diurnal pattern. An expression has been derived to explain the observed % SO₂ conversion on nylon filters as a combined effect of the ambient SO₂ concentration and relative humidity.     

Uptake of nitrous acid and nitrogen oxides by nylon surfaces: Implications for nitric acid measurement

The interference in HNO₃ determination due to HNO₂ and NO_x retention on nylon filters has been evaluated in laboratory and field conditions. Nitrous acid is retained on nylon filters with efficiencies varying from 25% at 12ℓ min⁻¹ to 80% at 2ℓ min⁻¹, yielding NO₂⁻ ion. In ambient sampling performed during photochemical smog episodes, NO₂⁻ is oxidized to NO₃⁻ with conversion factors up to 100%, resulting in a positive bias in HNO₃ determination.NO₂ reacts heterogeneously with H₂O on nylon surfaces according to the reaction 2NO₂ + H₂O → HNO₂ + HNO₃ with a removal constant of about 1 × 10⁻⁴ ms⁻¹ at a H₂O concentration of 20,000 ppm. The resulting nitrite and nitrate are independent of the sampling flow rate, while NO₂ concentration, sampling time and exposed nylon surface area play a directly proportional role. Accordingly, the relative interference of NO₂ with respect to HNO₃ determination is almost negligible for nylon filters, usually run at relatively high flow rates, while it may be significant for nylon denuders, which are characterized by larger exposed surfaces and lower operating flow rates.     

Mobility of radium and trace metals in sediments of the Winterbeek: Application of sequential extraction and DGT techniques

For several decades, phosphate ores containing ²²⁶Ra as well as several trace metals have been processed in Belgium to produce calcium phosphate for use in cattle food. The waste water is discharged in two small rivers, the Laak and the Winterbeek.In this study, the levels of ²²⁶Ra and trace metals in surface water and sediments of the Winterbeek were investigated and the mobility of these compounds was assessed using DGT (Diffusive Gradient in Thin Films) and sequential extraction techniques.The concentrations of ²²⁶Ra and trace metals in water and sediment indicate a decreasing trend in inputs to the Winterbeek.The mobility of ²²⁶Ra, assessed by DGT, is related to the reductive mobilization of Fe. The sequential extraction technique shows that at some stations an important fraction of ²²⁶Ra is found to labile sediment phases.Diffusive ²²⁶Ra sediment fluxes, are however, relatively small and have only a minor contribution to the water column concentration of ²²⁶Ra.     

Metals emitted from heavy-duty diesel vehicles equipped with advanced PM and NOX emission controls

Emission factors for elemental metals were determined from several heavy-duty diesel vehicles (HDDV) of 1998–2007 vintage, operating with advanced PM and/or NO_X emissions control retrofits on a heavy-duty chassis dynamometer, under steady state cruise, transient, and idle conditions. The emission control retrofits included diesel particulate filters (DPF): catalyzed and uncatalyzed, passive and active prototype vanadium- or zeolite-based selective catalytic reduction (SCR) systems, and a catalyzed DPF fitted on a hybrid diesel electric drive vehicle. The prototype SCR systems in combination with DPF retrofits are of particular interest because they represent the expected emissions controls for compliance with PM and NO_X regulations in 2010. PM samples from a full-exhaust dilution tunnel were collected on bulk filters, and on a Personal Cascade Impactor Sampler (PCIS) for total and water-soluble elemental analysis. All the DPFs significantly reduced emissions of total trace elements (>85% and >95% for cruise and for the Urban Dynamometer Driving Schedule (UDDS), respectively). However, we observed differences in the post-retrofit metals emissions due to driving cycle effects (i.e., exhaust temperature) and type of retrofit. In general, the metals emissions over cruise conditions (which leads to higher exhaust temperatures) were substantially different from the emissions over a transient cycle or while idling. For instance, during cruise, we observed higher levels of platinum (1.1 ± 0.6–4.2 ± 3.6 ng km^?1) for most of the retrofit-equipped vehicle tests compared to the baseline configuration (0.3 ± 0.1 ng km^?1). The vanadium-based DPF + SCR vehicle during cruise operation exhibited emissions of vanadium (562 ± 265 ng km^?1) and titanium (5841 ± 3050 ng km^?1), suggesting the possible release of actual SCR wash-coat (V₂O₅/TiO₂) from the catalyst under the higher temperatures characteristic of cruise operation. The vanadium emissions exhibited a bi-modal mass size distribution, with modes at <0.25 μm and 1.0–2.5 μm size ranges for the vanadium-based SCR system. For the DPF + SCR systems, a greater fraction of the metal emissions from the zeolite-based system is water-soluble compared to emissions from the vanadium-based system.     

Indoor-outdoor Carbon Monoxide Concentrations at Four Sites in Riyadh,Saudi Arabia

Abstract

Nylon filters are a popular medium to collect atmospheric fine particles in different aerosol monitoring networks, including those operated by the U.S. Environmental Protection Agency and the Interagency Monitoring of Protected Visual Environments (IMPROVE) program. Extraction of the filters by deionized water or by a basic aqueous solution (typically a mixture of sodium carbonate and sodium bicarbonate) is often performed to permit measurement of the inorganic ion content of the collected particles. Whereas previous studies have demonstrated the importance of using a basic solution to efficiently extract gaseous nitric acid collected using nylon filters, there has been a recent movement to the use of deionized water for extraction of particles collected on nylon filters to eliminate interference from sodium ion (Na⁺) during ion chromatographic analysis of inorganic aerosol cations. Results are reported here from a study designed to investigate the efficiency of deionized water extraction of aerosol nitrate (NO₃ ^?) and sulfate from nylon filters. Data were obtained through the conduct of five field experiments at selected IMPROVE sites. Results indicate that the nylon filters provide superior retention of collected fine particle NO₃ ^?, relative to Teflon filters, and that deionized water extraction (with ultrasonication) of collected NO₃ ^? and sulfate is as efficient, for the situations studied, as extraction using a basic solution of 1.7 mM sodium bicarbonate and 1.8 mM sodium carbonate.     

Dissolution of trace metals from particles of industrial origin and its influence on the composition of rainwater

The dissolution of trace metals (Fe, Mn, Cu, Zn, Ca and Mg) from pulverized fuel ash and steel dust particles in aqueous suspensions was studied as a function of solution pH and aerosol mass loading. The rate of dissolution, the final concentration and the fraction of the metal leached increased with decreasing pH over the range of pH 2.5→ 5. The leaching of aerosol particles is an important source of trace metals in rainwater, and the results of the leaching experiments were found to be consistent with the observations of these metals in urban rainwater. Alkaline materials such as Ca and Mg leached from particles may be important in the electroneutrality balance of rainwater and they could affect the solution pH. The dissolution of metals such as Fe and Mn may provide catalysts which could be important in the aqueous oxidation of SO₂, and the leaching of Ca and Mg may have a ‘buffering’ effect in reacting cloud and aerosol droplets.     

光纤传导可见光降解亚甲基蓝

针对浓度大、色度高的印染废水难以处理的情况,选用加入光纤的光催化体系进行研究。采用溶胶凝胶法制备了Ag+/TiO2粉体光催化剂,用固体紫外可见光谱、X射线衍射对其进行表征。选用亚甲基蓝溶液作为目标降解物,评价了Ag+/TiO2在可见光下的光催化活性。分别考察了加入石英芯侧光光纤与塑料侧光光纤反应体系下,催化剂量、光纤数量、光照强度和pH值等因素对亚甲基蓝降解实验的影响。结果表明,选用20 mg/L的亚甲基蓝,采用催化剂量为11.67 g/L,500根侧光光纤,300 W的外部光源,pH值约为11时,光催化降解效果最佳,均能达到90%以上。     

SARA Title III,Section 313 —Looking Ahead

This study performed a workplace evaluation of emission control using available air sampling filters and characterized the emitted particles captured in filters. Characterized particles were contained in the exhaust gas released from carbon nanotube (CNT) synthesis using chemical vapor deposition (CVD). Emitted nanoparticles were collected on grids to be analyzed using transmission electron microscopy (TEM). CNT clusters in the exhaust gas were collected on filters for investigation. Three types of filters, including Nalgene surfactant-free cellulose acetate (SFCA), Pall A/E glass fiber, and Whatman QMA quartz filters, were evaluated as emission control measures, and particles deposited in the filters were characterized using scanning transmission electron microscopy (STEM) to further understand the nature of particles emitted from this CNT production. STEM analysis for collected particles on filters found that particles deposited on filter fibers had a similar morphology on all three filters, that is, hydrophobic agglomerates forming circular beaded clusters on hydrophilic filter fibers on the collecting side of the filter. CNT agglomerates were found trapped underneath the filter surface. The particle agglomerates consisted mostly of elemental carbon regardless of the shapes. Most particles were trapped in filters and no particles were found in the exhaust downstream from A/E and quartz filters, while a few nanometer-sized and submicrometer-sized individual particles and filament agglomerates were found downstream from the SFCA filter. The number concentration of particles with diameters from 5 nm to 20 µm was measured while collecting particles on grids at the exhaust piping. Total number concentration was reduced from an average of 88,500 to 700 particle/cm³ for the lowest found for all filters used. Overall, the quartz filter showed the most consistent and highest particle reduction control, and exhaust particles containing nanotubes were successfully collected and trapped inside this filter.

Implications: As concern for the toxicity of engineered nanoparticles grows, there is a need to characterize emission from carbon nanotube synthesis processes and to investigate methods to prevent their environmental release. At this time, the particles emitted from synthesis were not well characterized when collected on filters, and limited information was available about filter performance to such emission. This field study used readily available sampling filters to collect nanoparticles from the exhaust gas of a carbon nanotube furnace. New agglomerates were found on filters from such emitted particles, and the performance of using the filters studied was encouraging in terms of capturing emissions from carbon nanotube synthesis.     

Time study of trace elements and major ions during two cloud events at the Mt. Brocken

Cloud water investigations have been performed at the highest elevation of Central Germany in 1997. Results of extensive trace element measurements are presented. Besides conductivity, pH, liquid water content and major ions the data set includes 49 minor and trace elements. Estimation of crustal enrichment factors (EFs) provides an indication of the anthropogenic contributions to the cloud water concentrations. The variation of cloud composition with time has been illustrated for two selected events with different air mass origins. The chemical composition of the cloud condensation nuclei on which the droplets grow mainly determines the cloud water chemistry. For a cloud event in June 1997 the concentrations of the crustally derived elements Si, Al, Fe, Ti, Ce, La and Nd follow each other closely. The fact that SO₄²⁻, NO₃⁻ and NH₄⁺ are only moderately correlated with the particular pollutants with high enrichment factors such as Cd, Sb, Pb, Zn, Cu, As, Bi, Sn, Mo, Ni, Tl and V indicates that their source regions are more widespread. During an event in October 1997 the time trends for most minor and trace elements follow rather closely those for the major ions NH₄⁺, SO₄²⁻ and NO₃⁻. Back trajectories show that the transport from continental and marine European sources was the likely cause of the sample concentrations. EFs of trace elements in cloud water samples during the June and October event show a strong correlation with those obtained for urban particulate matter. Although both events are influenced by air masses of different origin, there is a good agreement between the EF signatures.     

混合固定化硝化菌和好氧反硝化菌处理焦化废水

对传统的聚乙烯醇(PVA)固定化方法进行了改进,试制了加入麦秸粉末的固定化球和以活性炭纤维膜为载体膜固定化细胞产品。混合固定化硝化细菌和好氧反硝化细菌对经过厌氧折流板反应器酸化后的焦化废水进行脱氮,焦化废水在厌氧折流板反应器中经过18 h的酸化后,pH在8.0左右,开始进入好氧槽进行脱氮。在有效容积为5 L好氧槽中经过12 h的曝气处理,加入麦秸粉末的固定化球对氨氮的去除率高达94.3%;纤维膜固定化细胞产品对氨氮的去除率为85%。整个脱氮过程无NO^-₂-N和NO^-₂-N的积累,实现了好氧条件下的同时硝化和反硝化。     

Quantitative assessment of the toxic effects of heavy metals on 1,2-dichloroethane biodegradation in co-contaminated soil under aerobic condition

1,2-Dichloroethane (1,2-DCA) is one of the most hazardous pollutant of soil and groundwater, and is produced in excess of 5.44 × 10⁹ kg annually. Owing to their toxicity, persistence and potential for bioaccumulation, there is a growing interest in technologies for their removal. Heavy metals are known to be toxic to soil microorganisms at high concentrations and can hinder the biodegradation of organic contaminants. In this study, the inhibitory effect of heavy metals, namely; arsenic, cadmium, mercury and lead, on the aerobic biodegradation of 1,2-DCA by autochthonous microorganisms was evaluated in soil microcosm setting. The presence of heavy metals was observed to have a negative impact on the biodegradation of 1,2-DCA in both soil samples tested, with the toxic effect being more pronounced in loam soil, than in clay soil. Generally, 75 ppm As³⁺, 840 ppm Hg²⁺, and 420 ppm Pb²⁺ resulted in 34.24%, 40.64%, and 45.94% increase in the half live (t_½) of 1,2-DCA, respectively, in loam soil, while concentrations above 127.5 ppm Cd²⁺, 840 ppm Hg²⁺ and 420 ppm of Pb²⁺ and less than 75 ppm As³⁺ was required to cause a >10% increase in the t_½ of 1,2-DCA in clay soil. A dose-dependent relationship between degradation rate constant (k₁) of 1,2-DCA and metal ion concentrations was observed for all the heavy metals tested, except for Hg²⁺. This study demonstrated that different heavy metals have different impacts on the degree of 1,2-DCA degradation. Results also suggest that the degree of inhibition is metal specific and is also dependent on several factors including; soil type, pH, moisture content and available nutrients.     

Levels and distribution of heavy metals in atmospheric particular matters over the northern South China Sea

Oceans play a significant role in the cycling of trace metals and persistent organic pollutants. In this study, aerosol samples covering the whole northern South China Sea (SCS) were collected in 2005 and 2007, respectively, for analysis of trace metals and major elements. The levels of trace metals detected ranged from 0.514 to 119 ng/m³ in 2005 and from 0.130 to 24.2 ng/m³ in 2007, respectively. Cu, Zn, and Pb were the three predominant metals with high enrichment factors (>10), indicating the strong anthropogenic inputs. The trace metals over SCS were comparable to the values in suburban and background sites of South China, but generally higher than those over other seas and oceans. Considering the fact that they were influenced by their proximity to source regions and air mass origins, the elevated metals in 2005 were probably attributed to the strong wind and long-range atmospheric transport driven by Asian monsoon.     

A dynamic dilution system for the production of sub-ppb concentrations of reactive and labile species

A three-stage dynamic dilution system has been developed capable of generating calibration standards below 100 pptv using gravimetrically calibrated permeation tubes as a trace species source. Multistage dilution permits the use of equivalent one-step diluent flows approaching 1000 std 1 min ⁻¹. An allfluorocarbon flow path facilitates the handling of reactive and labile species. Accuracies of about ± 3 % have been demonstrated for several sulfur compounds including H₂S and SO₂ at mixing ratios below 200 ppt.     

Kinetic and equilibrium studies of adsorptive removal of phenol onto eggshell waste

The aim of the present research is to develop economic, fast, and versatile method for the removal of toxic organic pollutant phenol from wastewater using eggshell. The batch experiments are conducted to evaluate the effect of pH, phenol concentration, dosage of adsorbent, and contact time on the removal of phenol. The paper includes in-depth kinetic studies of the ongoing adsorption process. Attempts have also been made to verify Langmuir and Freundlich adsorption isotherms. The morphology and characteristics of eggshell have also been studied using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and X-ray fluorescence analysis. At ambient temperature, the maximum adsorption of phenol onto eggshells has been achieved at pH 9 and the contact time, 90 min. The experimental data give best-fitted straight lines for pseudo-first-order as well as pseudo-second-order kinetic models. Furthermore, the adsorption process verifies Freundlich and Langmuir adsorption isotherms, and on the basis of mathematical expressions of these models, various necessary adsorption constants have been calculated. Using adsorption data, various thermodynamic parameters like change in enthalpy (?H ⁰), change in entropy (?S ⁰), and change in free energy ?G ⁰ have also been evaluated. Results clearly reveal that the solid waste material eggshell acts as an effective adsorbent for the removal of phenol from aqueous solutions.