Measurement and Analysis of the Relationship between Ammonia,Acid Gases,and Fine Particles in Eastern North Carolina

Abstract

An annular denuder system, which consisted of a cyclone separator; two diffusion denuders coated with sodium carbonate and citric acid, respectively; and a filter pack consisting of Teflon and nylon filters in series, was used to measure acid gases, ammonia (NH₃), and fine particles in the atmosphere from April 1998 to March 1999 in eastern North Carolina (i.e., an NH₃?rich environment). The sodium carbonate denuders yielded average acid gas concentrations of 0.23 μg/m³ hydrochloric acid (standard deviation [SD] ± 0.2 μg/m³); 1.14 μg/m³ nitric acid (SD ± 0.81 μg/m³), and 1.61 μg/m³ sulfuric acid (SD ± 1.58 μg/m³). The citric acid denuders yielded an average concentration of 17.89 μg/m³ NH₃ (SD ± 15.03 μg/m³). The filters yielded average fine aerosol concentrations of 1.64 μg/m³ ammonium (NH₄ ⁺;SD ± 1.26 μg/m³); 0.26 μg/m³ chloride (SD ± 0.69 μg/m³), 1.92 μg/m³ nitrate (SD ± 1.09 μg/m³), and 3.18 μg/m³ sulfate (SO₄ ^2?; SD ± 3.12 μg/m³). From seasonal variation, the measured particulates (NH₄ ⁺,SO₄ ^2?, and nitrate) showed larger peak concentrations during summer, suggesting that the gas-to-particle conversion was efficient during summer. The aerosol fraction in this study area indicated the domination of ammonium sulfate particles because of the local abundance of NH₃, and the long-range transport of SO₄ ^2? based on back trajectory analysis. Relative humidity effects on gas-to-particle conversion processes were analyzed by particulate NH₄ ⁺ concentration originally formed from the neutralization processes with the secondary pollutants in the atmosphere.     

Distribution characteristics of polychlorinated biphenyls in crucian carp (Carassius auratus) from major rivers in Korea

Polychlorinated biphenyls (PCBs) levels in crucian carp were determined at 20 locations along four major river systems, several small-scale rivers and a wetland in Korea. Twenty-eight congeners, ranging from tri- to hepta-CBs were detected. A gas chromatograph with a mass selective detector was used to quantify the individual PCB congeners. The objectives of this study were to investigate the levels of contamination of PCBs in freshwater fish and to observe the pattern of their distribution. The sampling locations were chosen among 31 sampling sites that are currently used as environmental residue checkpoints by the Korean Ministry of Environment. Concentrations of individual congeners ranged from not detectable (n.d.) to 0.75 ng g(-1) on a wet weight basis. The total concentrations of PCBs at each site ranged from n.d. to 5.41 ng g(-1) of wet weight. The most heavily contaminated site was the Nakdong estuary located near the Shinpyung-Janglim factory district. The PCB 153 and 138 were the principal congeners and penta- and hexa-chlorinated biphenyls comprised the main congener groups.     

Chemical coupling between ammonia, acid gases, and fine particles

The concentrations of inorganic aerosol components in the fine particulate matter (PM(fine)< or =2.5 microm) consisted of primarily ammonium, sodium, sulfate, nitrate, and chloride are related to the transfer time scale between gas to particle phase, which is a function of the ambient temperature, relative humidity, and their gas phase constituent concentrations in the atmosphere. This study involved understanding the magnitude of major ammonia sources; and an up-wind and down-wind (receptor) ammonia, acid gases, and fine particulate measurements; with a view to accretion gas-to-particle conversion (GTPS) process in an agricultural/rural environment. The observational based analysis of ammonia, acid gases, and fine particles by annular denuder system (ADS) coupled with a Gaussian dispersion model provided the mean pseudo-first-order k(S-1) between NH(3) and H(2)SO(4) aerosol approximately 5.00 (+/-3.77)x10(-3) s(-1). The rate constant was found to increase as ambient temperature, wind speed, and solar radiation increases, and decreases with increasing relative humidity. The observed [NH(3)][HNO(3)] products exceeded values predicted by theoretical equilibrium constants, due to a local excess of ammonia concentration.     

Measurement and analysis of the relationship between ammonia, acid gases, and fine particles in eastern North Carolina

An annular denuder system, which consisted of a cyclone separator; two diffusion denuders coated with sodium carbonate and citric acid, respectively; and a filter pack consisting of Teflon and nylon filters in series, was used to measure acid gases, ammonia (NH3), and fine particles in the atmosphere from April 1998 to March 1999 in eastern North Carolina (i.e., an NH3-rich environment). The sodium carbonate denuders yielded average acid gas concentrations of 0.23 microg/m3 hydrochloric acid (standard deviation [SD] +/- 0.2 microg/m3); 1.14 microg/m3 nitric acid (SD +/- 0.81 microg/m3), and 1.61 microg/m3 sulfuric acid (SD +/- 1.58 microg/m3). The citric acid denuders yielded an average concentration of 17.89 microg/m3 NH3 (SD +/- 15.03 microg/m3). The filters yielded average fine aerosol concentrations of 1.64 microg/m3 ammonium (NH4+; SD +/- 1.26 microg/m3); 0.26 microg/m3 chloride (SD +/- 0.69 microg/m3), 1.92 microg/m3 nitrate (SD +/- 1.09 microg/m3), and 3.18 microg/m3 sulfate (SO4(2-); SD +/- 3.12 microg/m3). From seasonal variation, the measured particulates (NH4+, SO4(2-), and nitrate) showed larger peak concentrations during summer, suggesting that the gas-to-particle conversion was efficient during summer. The aerosol fraction in this study area indicated the domination of ammonium sulfate particles because of the local abundance of NH3, and the long-range transport of SO4(2-) based on back trajectory analysis. Relative humidity effects on gas-to-particle conversion processes were analyzed by particulate NH4+ concentration originally formed from the neutralization processes with the secondary pollutants in the atmosphere.     

Congratulatory Address

Water, Air, &; Soil Pollution: Focus -     

Uranium and neptunium retention mechanisms in Gallionella ferruginea/ferrihydrite systems for remediation purposes

The ubiquitous β-Proteobacterium Gallionella ferruginea is known as stalk-forming, microaerophilic iron(II) oxidizer, which rapidly produces iron oxyhydroxide precipitates. Uranium and neptunium sorption on the resulting intermixes of G. ferruginea cells, stalks, extracellular exudates, and precipitated iron oxyhydroxides (BIOS) was compared to sorption to abiotically formed iron oxides and oxyhydroxides. The results show a high sorption capacity of BIOS towards radionuclides at circumneutral pH values with an apparent bulk distribution coefficient (K_d) of 1.23 × 10⁴ L kg^?1 for uranium and 3.07 × 10⁵ L kg^?1 for neptunium. The spectroscopic approach by X-ray absorption spectroscopy (XAS) and ATR FT-IR spectroscopy, which was applied on BIOS samples, showed the formation of inner-sphere complexes. The structural data obtained at the uranium L_III-edge and the neptunium L_III-edge indicate the formation of bidentate edge-sharing surface complexes, which are known as the main sorption species on abiotic ferrihydrite. Since the rate of iron precipitation in G. ferruginea-dominated systems is 60 times faster than in abiotic systems, more ferrihydrite will be available for immobilization processes of heavy metals and radionuclides in contaminated environments and even in the far-field of high-level nuclear waste repositories.

     

A hierarchical end-of-life decision model for determining the economic levels of remanufacturing and disassembly under environmental regulations

Remanufacturing, in contrast to material recycling and disposal, can reduce environmental impacts by retaining the geometrical form of the product, thereby regarded as a more eco-efficient approach. In this paper, an end-of-life (EOL) decision model for remanufacturing options is presented to facilitate remanufacturing. The proposed model, in order to maximize the economic value of remanufacturing options while meeting environmental regulations, takes an integrative approach to EOL-option decision-making. Also presented in this paper is a hierarchical approach that represents both the overall hierarchical structure of a product and the interconnections among components. Illustrative examples are provided to demonstrate the effectiveness of the model.     

Multispecies and Multiscale Conservation Planning: Setting Quantitative Targets for Red‐Listed Lichens on Ancient Oaks

Abstract: Species occurrence in a habitat patch depends on local habitat and the amount of that habitat in the wider landscape. We used predictions from empirical landscape studies to set quantitative conservation criteria and targets in a multispecies and multiscale conservation planning effort. We used regression analyses to compare species richness and occurrence of five red‐listed lichens on 50 ancient oaks (Quercus robur; 120–140 cm in diameter) with the density of ancient oaks in circles of varying radius from each individual oak. Species richness and the occurrence of three of the five species were best explained by increasing density of oaks within 0.5 km; one species was best explained by the density of oaks within 2 km, and another was best predicted by the density of oaks within 5 km. The minimum numbers of ancient oaks required for “successful conservation” was defined as the number of oaks required to obtain a predicted local occurrence of 50% for all species included or a predicted local occurrence of 80% for all species included. These numbers of oaks were calculated for two relevant landscape scales (1 km² and 13 km²) that corresponded to various species responses, in such a way that calculations also accounted for local number of oaks. Ten and seven of the 50 ancient oaks surveyed were situated in landscapes that already fulfilled criteria for successful conservation when the 50% and 80% criteria, respectively, were used to define the level of successful conservation. For cost‐efficient conservation, oak stands in the landscapes most suitable for successful conservation should be prioritized for conservation and management (e.g., grazing and planting of new oaks) at the expense of oak stands situated elsewhere.