Seasonal and Spatial Variations of Ammonia Emissions from an Open-Lot Dairy Operation

Abstract

There is a need for a robust and accurate technique to measure ammonia (NH₃) emissions from animal feeding operations (AFOs) to obtain emission inventories and to develop abatement strategies. Two consecutive seasonal studies were conducted to measure NH₃ emissions from an open-lot dairy in central Texas in July and December of 2005. Data including NH₃ concentrations were collected and NH₃ emission fluxes (EFls), emission rates (ERs), and emission factors (EFs) were calculated for the open-lot dairy. A protocol using flux chambers (FCs) was used to determine these NH₃ emissions from the open-lot dairy. NH₃ concentration measurements were made using chemiluminescence-based analyzers. The ground-level area sources (GLAS) including open lots (cows on earthen corrals), separated solids, primary and secondary lagoons, and milking parlors were sampled to estimate NH₃ emissions. The seasonal NH₃ EFs were 11.6 ± 7.1 kg-NH₃ yr^-1head^-1 for the summer and 6.2 ± 3.7 kg-NH₃ yr^-1head^-1 for the winter season. The estimated annual NH₃ EF was 9.4 ± 5.7 kg-NH₃ yr^-1head^-1 for this open-lot dairy. The estimated NH₃ EF for winter was nearly 47% lower than summer EF. Primary and secondary lagoons (～37) and open-lot corrals (～63%) in summer, and open-lot corrals (～95%) in winter were the highest contributors to NH₃ emissions for the open-lot dairy. These EF estimates using the FC protocol and real-time analyzer were lower than many previously reported EFs estimated based on nitrogen mass balance and nitrogen content in manure. The difference between the overall emissions from each season was due to ambient temperature variations and loading rates of manure on GLAS. There was spatial variation of NH₃ emission from the open-lot earthen corrals due to variable animal density within feeding and shaded and dry divisions of the open lot. This spatial variability was attributed to dispirit manure loading within these areas.     

Ammonia volatilization loss from surface applied livestock manure

Ammonia (NH₃) emission from livestock manures used in agriculture reduces N uptake by crops and negatively impacts air quality. This laboratory study was conducted to evaluate NH₃emission from different livestock manures applied to two soils: Candler fins sand (CFS; light-textured soil, pH 6.8 and field capacity soil water content of 70 g kg^{? 1}) from Lake Alfred, Florida and Ogeechee loamy sand (OLS; medium-textured soil, pH 5.2 and field capacity soil water content of 140 g kg^{? 1}) from Savannah, Georgia. Poultry litter (PL) collected from a poultry farm near Douglas, Georgia, and fresh solid separate of swine manure (SM) collected from a farm near Clinton, North Carolina were used. Each of the soil was weighed in 100 g sub samples and amended with either PL or SM at rates equivalent to either 0, 2.24, 5.60, 11.20, or 22.40 Mg ha^{? 1} in 1L Mason jars and incubated in the laboratory at field capacity soil water content for 19 days to monitor NH₃ volatilization. Results indicated a greater NH₃ loss from soils amended with SM compared to that with PL. The cumulative NH₃volatilization loss over 19 days ranged from 4 to 27% and 14 to 32% of total N applied as PL and SM, respectively. Volatilization of NH₃ was greater from light-textured CFS than that from medium-textured OLS. Volatilization loss increased with increasing rates of manure application. Ammonia volatilization was lower at night time than that during the day time. Differences in major factors such as soil water content, temperature, soil type and live stock manure type influenced the diurnal variation in volatilization loss of NH₃ from soils. A significant portion (> 50%) of cumulative NH₃ emission over 19 d occurred during the first 5–7 d following the application of livestock manures. Results of this study demonstrate that application of low rates of livestock manure (≤ 5.60 Mg ha^{? 1}) is recommended to minimize NH₃ emissions.     

Sources of submicron aerosol during fog-dominated wintertime at Kanpur

The main objective of this atmospheric study was to determine the major sources of PM₁ (particles having aerodynamic diameter <1.0 μm) within and near the city of Kanpur, in the Indo-Gangetic Plain. Day and night, 10 h long each, filter-based aerosol samples were collected for 4 months (November 2009 to February 2010) throughout the winter season. These samples were subjected to gravimetric and quantitative chemical analyses for determining water-soluble ions (NH₄ ⁺, F^?, Cl^?, NO₃ ^?, and SO₄ ^2?) using an ion chromatograph and trace elements using an inductively coupled plasma–optical emission spectrometer. The mean PM₁ mass concentrations were recorded as 114?±?71 μg/m³ (day) and 143?±?86 μg/m³ (night), respectively. A significantly higher diurnal contribution of ions (NH₄ ⁺, F^?, Cl^?, NO₃ ^?, and SO₄ ^2?) in PM₁ mass was observed during the fog-affected days and nights throughout the winter season, for which the average values were recorded as 38.09?±?13.39 % (day) and 34.98?±?12.59 % (night), respectively, of the total PM₁ mass. This chemical dataset was then used in a source-receptor model, UNMIX, and the model results are described in detail. UNMIX provided a maximum number of five source factors, including crustal material, composite vehicle, secondary aerosol, coal combustion, and iron/steel production and metallurgical industries, as the dominant air pollution sources for this study.     

Characterization of carbonaceous aerosols over Delhi in Ganga basin: seasonal variability and possible sources

The mass concentration of carbonaceous species, organic carbon (OC), and elemental carbon (EC) using a semicontinuous thermo-optical EC-OC analyzer, and black carbon (BC) using an Aethalometer were measured simultaneously at an urban mega city Delhi in Ganga basin from January 2011 to May 2012. The concentrations of OC, EC, and BC exhibit seasonal variability, and their concentrations were ～2 times higher during winter (OC 38.1?±?17.9 μg m^?3, EC 15.8?±?7.3 μg m^?3, and BC 10.1?±?5.3 μg m^?3) compared to those in summer (OC 14.1?±?4.3 μg m^?3, EC 7.5?±?1.5 μg m^?3, and BC 4.9?±?1.5 μg m^?3). A significant correlation between OC and EC (R?=?0.95, n?=?232) indicate their common emission sources with relatively lower OC/EC ratio (range 1.0–3.6, mean 2.2?±?0.5) suggests fossil fuel emission as a major source of carbonaceous aerosols over the station. On average, mass concentration of EC was found to be ～38 % higher than BC during the study period. The measured absorption coefficient (b_abs) was significantly correlated with EC, suggesting EC as a major absorbing species in ambient aerosols at Delhi. Furthermore, the estimated mass absorption efficiency (σ_abs) values are similar during winter (5.0?±?1.5 m² g^?1) and summer (4.8?±?2.8 m² g^?1). Significantly high aerosol loading of carbonaceous species emphasize an urgent need to focus on air quality management and proper impact assessment on health perspective in these regions.     

Measurement of Organic Acids,Aldehydes, and Ketones in Residential Environments and Their Relation to Ozone

Abstract

Ozone and several polar volatile organic compounds (VOCs) including organic acids and carbonyls (aldehydes and ketones) were measured over an approximately 24 hour period in four residences during the winter of 1993 and in nine residences during the summer of 1993. All residences were in the greater Boston, Massachusetts area. The relation of the polar VOCs to the ozone concentration was examined. Indoor carbonyl concentrations were similar between the summer and winter, with the total mean winter concentration being 31.7 ppb and the total mean summer concentration being 36.6 ppb. However, the average air exchange rate was 0.9 hr^?1 during the winter and 2.6 hr^?1 during the summer. Therefore, the estimated carbonyl emission rates were significantly higher during the summer. Indoor organic acid concentrations were about twice as high during the summer as during the winter. For formic acid, the indoor winter mean was 9.8 ppb, and the summer indoor mean was 17.8 ppb. For acetic acid, the indoor winter mean was 15.5 ppb, and the summer indoor mean was 28.7 ppb. The concentrations of the polar VOCs were found to be significantly correlated with one another. Also, the emission rates of the polar VOCs were found to be correlated with both the environmental variables such as temperature and relative humidity and the ozone removal rate; however, it was difficult to apportion the relative effects of the environmental variables and the ozone removal.     

Ammonia emissions from naturally ventilated dairy cattle buildings and outdoor concrete yards in Portugal

There is a lack of information on ammonia (NH₃) emissions from cattle housing systems in Mediterranean countries, with most published data deriving from NW Europe. An investigation was carried out in NW Portugal to quantify NH₃ emissions for the main types of dairy cattle buildings in Portugal, i.e. naturally ventilated buildings and outdoor concrete yards, and to derive robust emission factors (EFs) for these conditions and compare with EFs used elsewhere in Europe. Measurements were made throughout a 12-month period using the passive flux sampling method in the livestock buildings and the equilibrium concentration technique in outdoor yards.The mean NH₃ emission factor for the whole housing system (buildings + outdoor yards) was 43.7 g NH₃–N LU^?1 day^?1 and for outdoor concrete yards used by dairy cattle was 26.6 g NH₃–N LU^?1 day^?1. Expressing NH₃ emission in terms of the quantity of liquid milk produced gave similar values across the three dairy farms studied (with a mean of 2.3 kg N ton-milk^?1 produced) and may have advantages when comparing different farming systems. In dairy houses with outdoor yards, NH₃ emissions from the yard area contributed to 69–92% of total emissions from this housing system. Emissions were particularly important during spring and summer seasons from outdoor yards with NH₃ emitted in this period accounting for about 72% of annual emissions from outdoor yards. Mean NH₃ emission factors derived for this freestall housing system and outdoor concrete yards used by dairy cattle in Portugal were higher than those measured in northern Europe. In addition, values of animal N excretion estimated in this study were greater than official National standard values. If these emissions are typical for Portuguese dairy systems, then the current National inventory underestimates emissions from this source in NW of Portugal, because of the use of lower standard values of N excretion by dairy cattle.     

Size mass distribution of water-soluble ionic species and gas conversion to sulfate and nitrate in particulate matter in southern Taiwan

A Micro-Orifice Uniform Deposition Impactor (MOUDI) and a Nano-MOUDI were employed to determine the size-segregated mass distributions of ambient particulate matter (PM) and water-soluble ionic species for particulate constituents. In addition, gas precursors, including HCl, HONO, HNO₃, SO₂, and NH₃ gases, were analyzed by an annular denuder system. PM size mass distribution, mass concentration, and ionic species concentration were measured during the day and at night during episode and non-episode periods in winter and summer. Average total suspended particle (TSP) concentrations during episode days in winter were as high as 153?±?33 μg/m³, and PM mass concentrations in summer were as low as one-third of that in winter. Generally, PM concentration at night was higher than that in the daytime in southern Taiwan during the sampling periods. In winter during the episode periods, the size-segregated mass distribution of PM mass concentration was mostly in the 0.32–3.2-μm range, and the PM concentration increased significantly in the range of 0.32–3.2 μm at night. Ammonium, nitrate, and sulfate were the dominant water-soluble ionic species in PM, contributing 34–48 % of TSP mass. High concentrations of ammonia (12.9–49 μg/m³) and SO₂ (2.6–27 μg/m³) were observed in the gas precursors. The conversion ratio was high in the PM size range of 0.18–3.2 μm both during the day and at night in winter, and the conversion ratio of episode days was 20 % higher than that of non-episode days. The conversion factor was high for both nitrogen and sulfur species at nighttime, especially on episode days.     

Consultant Guide/1986

ABSTRACT

To obtain annual odor emission profiles from intensive swine operations, odor concentrations and emission rates were measured monthly from swine nursery, farrowing, and gestation rooms for a year. Large annual variations in odor concentrations and emissions were found in all the rooms and the impact of the seasonal factor (month) was significant (P < 0.05). Odor concentration was low in summer when ventilation rate was high but high in winter when ventilation rate was low, ranging from 362 (farrowing room in July) to 8934 (nursery room in December) olfactory unit (OU) m^?3. This indicates that the air quality regarding odor was significantly better in summer than that in winter. Odor emission rate did not show obvious seasonal pattern as odor concentration did, ranging from 2 (gestation room in November) to 90 (nursery room in April) OU m^?2 sec^?1; this explains why the odor complaints for swine barns have occurred all year round. The annual geometric mean odor concentration and emission rate of the nursery room was significantly higher than the other rooms (P < 0.05). In order to obtain the representative annual emission rate, measurements have to be taken at least monthly, and then the geometric mean of the monthly values will represent the annual emission rate. Incorporating odor control technologies in the nursery area will be the most efficient in reducing odor emission from the farm considering its emission rate was 2 to 3 times of the other areas. The swine grower-finisher area was the major odor source contributing 53% of odor emission of the farm and should also be targeted for odor control. Relatively positive correlations between odor concentration and both H₂S and CO₂ concentrations (R ² = 0.58) means that high level of these two gases might likely indicate high odor concentration in swine barns.

IMPLICATIONS The emissions of air pollutants including odors, greenhouse gases, and toxic gases have become a major environmental issue facing animal farms in the U.S.A. and Canada. To ensure the air quality in the vicinity of intensive livestock farms, air dispersion models have been used to determine setback distances between livestock facilities and neighboring residences based on certain air quality requirement on odor and gases. Due to the limited odor emission data available, none of the existing models can take account of seasonal variations of odor emissions, which may result in great uncertainties in setback distance calculations. Therefore, the obtained seasonal odor and gas emission rates by this study can be used by the government regulatory organizations and researchers in air dispersion modeling to get improved calculation of setback distances.     

Sensitivity analyses of factors influencing CMAQ performance for fine particulate nitrate

Improvement of air quality models is required so that they can be utilized to design effective control strategies for fine particulate matter (PM_2.5). The Community Multiscale Air Quality modeling system was applied to the Greater Tokyo Area of Japan in winter 2010 and summer 2011. The model results were compared with observed concentrations of PM_2.5 sulfate (SO₄^2-), nitrate (NO₃^?) and ammonium, and gaseous nitric acid (HNO₃) and ammonia (NH₃). The model approximately reproduced PM_2.5 SO₄^2? concentration, but clearly overestimated PM_2.5 NO₃^? concentration, which was attributed to overestimation of production of ammonium nitrate (NH₄NO₃). This study conducted sensitivity analyses of factors associated with the model performance for PM_2.5 NO₃^? concentration, including temperature and relative humidity, emission of nitrogen oxides, seasonal variation of NH₃ emission, HNO₃ and NH₃ dry deposition velocities, and heterogeneous reaction probability of dinitrogen pentoxide. Change in NH₃ emission directly affected NH₃ concentration, and substantially affected NH₄NO₃ concentration. Higher dry deposition velocities of HNO₃ and NH₃ led to substantial reductions of concentrations of the gaseous species and NH₄NO₃. Because uncertainties in NH₃ emission and dry deposition processes are probably large, these processes may be key factors for improvement of the model performance for PM_2.5 NO₃^?.

Implications: The Community Multiscale Air Quality modeling system clearly overestimated the concentration of fine particulate nitrate in the Greater Tokyo Area of Japan, which was attributed to overestimation of production of ammonium nitrate. Sensitivity analyses were conducted for factors associated with the model performance for nitrate. Ammonia emission and dry deposition of nitric acid and ammonia may be key factors for improvement of the model performance.     

Spatial and temporal variations of nitrous oxide flux between coastal marsh and the atmosphere in the Yellow River estuary of China

To investigate the spatial and seasonal variations of nitrous oxide (N₂O) fluxes and understand the key controlling factors, we explored N₂O fluxes and environmental variables in high marsh (HM), middle marsh (MM), low marsh (LM), and mudflat (MF) in the Yellow River estuary throughout a year. Fluxes of N₂O differed significantly between sampling periods as well as between sampling positions. During all times of day and the seasons measured, N₂O fluxes ranged from ?0.0051 to 0.0805 mg N₂O m^?2 h^?1, and high N₂O emissions occurred during spring (0.0278 mg N₂O m^?2 h^?1) and winter (0.0139 mg N₂O m^?2 h^?1) while low fluxes were observed during summer (0.0065 mg N₂O m^?2 h^?1) and autumn (0.0060 mg N₂O m^?2 h^?1). The annual average N₂O flux from the intertidal zone was 0.0117 mg N₂O m^?2 h^?1, and the cumulative N₂O emission throughout a year was 113.03 mg N₂O m^?2, indicating that coastal marsh acted as N₂O source. Over all seasons, N₂O fluxes from the four marshes were significantly different (p?<?0.05), in the order of HM (0.0256?±?0.0040 mg N₂O m^?2 h^?1)?>?MF (0.0107?±?0.0027 mg N₂O m^?2 h^?1)?>?LM (0.0073?±?0.0020 mg N₂O m^?2 h^?1)?>?MM (0.0026?±?0.0011 mg N₂O m^?2 h^?1). Temporal variations of N₂O emissions were related to the vegetations (Suaeda salsa, Phragmites australis, and Tamarix chinensis) and the limited C and mineral N in soils during summer and autumn and the frequent freeze/thaw cycles in soils during spring and winter, while spatial variations were mainly affected by tidal fluctuation and plant composition at spatial scale. This study indicated the importance of seasonal N₂O contributions (particularly during non-growing season) to the estimation of local N₂O inventory, and highlighted both the large spatial variation of N₂O fluxes across the coastal marsh (CV?=?158.31 %) and the potential effect of exogenous nitrogen loading to the Yellow River estuary on N₂O emission should be considered before the annual or local N₂O inventory was evaluated accurately.     

Diurnal and seasonal variations of odor and gas emissions from a naturally ventilated free-stall dairy barn on the Canadian prairies

This study characterized the seasonal concentration (C) and emission (E) patterns of odor, ammonia (NH₃), and hydrogen sulfide (H₂S) over the course of a whole year and their diurnal patterns in cold, warm, and mild seasons for a naturally ventilated free-stall dairy barn. It was found that seasonal odor and NH₃ and H₂S emissions varied greatly: from 17.2 to 84.4 odor units (OU) sec^?1 AU^?1 (AU: animal unit, 500 kg of animal body mass), from 0.27 to 0.92 mg sec^?1 AU^?1, and from 3 to 105 μg sec^?1 AU^?1, respectively. The overall concentrations of odor and NH₃ were higher in the winter, whereas the emissions were higher in the mild and warm seasons. Diurnal variation was most significant for odor emission (OE) in the mild season when the ratio of maximum (279.2 OU sec^?1 AU^?1) to minimum value (60.5 OU sec^?1 AU^?1) was up to 4.6. The indoor air quality was also evaluated by considering not only the health effect of individual gases, but also the additive effect of NH₃ and H₂S. Results showed that the indoor air quality was poorest in cold seasons when NH₃ C could exceed the threshold limit set out in occupational health regulation, and in fact could worsen due to the additive effect of the two gases. Further, it was suggested NH₃ was a good indicator for predicting odor concentration (OC) or OE. The impact of climatic parameters on odor and gases were also examined, and it was found ventilation rate (VR) negatively affected OC and NH₃ C, but positively impacted OE and NH₃ E. Using 70% of the total data, a multilinear model for OE was developed as a function of VR and indoor relative humidity and was validated to be acceptable using the rest of the data.

Implications: Diurnal and seasonal variations of odor, NH₃, and H₂S concentrations and emissions were monitored for a naturally ventilated dairy barn in a cold region. The emission factors were calculated and indoor air quality was evaluated. The overall odor and NH₃ concentrations were higher in winter, whereas emissions were higher in the mild and warm seasons. Diurnal variation was most significant for odor emission in the mild season, when the ratio of maximum to minimum value was up to 4.6. The results can be used to estimate odor and gas emissions from other dairy barns in Canada and other cold regions.     

Biotrickling filtration of airborne styrene: A comparison of filtration media

This study compares the performances of fern and plastic chips as packing media for the biofiltration of a styrene-laden waste gas stream emitted in a plant for the manufacture of plastic door plates. Fern chips (with a specific surface area of 1090 m² m^?3) and plastic chips (with a specific surface area of 610 m² m^?3) were packed into a pilot-scale biotrickling filter with a total medium volume of 50 L for the performance test. Field waste gas with styrene concentrations in the range of 161–2390 mg Am^?3 at 28–30 °C) was introduced to the bed and a fixed empty-bed retention time (EBRT) of 21 sec, a volumetric gas flow rate of 8.57 m³ hr^?1, and superficial gas velocity of 53.6 m hr^?1 were maintained throughout the experimental period. Nutrients containing metal salts, nitrogen, phosphorus, and milk were supplemented to the filters for maintaining the microbial activities. Results reveal that the biotrickling filter developed in this study had the highest styrene monomer (SM) elimination capacities (170 g m^?3 hr^?1 for fern-chip packing and 300 g m^?3 hr^?1 for plastic-chip packing) among those cited in the literature. The plastic medium is a favorable substitute for endangered fern chips. The thermal-setting nature of plastic chips limits their recycle and reuse as raw materials, and the study provides an opportunity for the utilization of the materials.

Implications: Biotreatment of contaminants in air streams offers an inexpensive and efficient alternative to conventional technologies. Biofiltration has a great potential for the degradation of gas-borne styrene and total hydrocarbon (THC) removal efficiency of around 80%. The objective of this research was to compare the performances of fern chips and a kind of plastic chips as packing media for biofiltration of the styrene-laden waste gas stream emitted from cutting operations of stripes of premixed unsaturated polyester (UP) and styrene paste before hot-pressing operations for making plastic door plates. From a practical point of view, the plastic medium can be a good substitute medium for fern chips, which has been declared as a protected plant. This study provides an experimentally verified model for the design and operation of such biotreatment systems.     

Whole House Particle Removal and Clean Air Delivery Rates for In-Duct and Portable Ventilation Systems

Abstract

A novel method for determining whole house particle removal and clean air delivery rates attributable to central and portable ventilation/air cleaning systems is described. The method is used to characterize total and air-cleaner-specific particle removal rates during operation of four in-duct air cleaners and two portable air-cleaning devices in a fully instrumented test home. Operation of in-duct and portable air cleaners typically increased particle removal rates over the baseline rates determined in the absence of operating a central fan or an indoor air cleaner. Removal rates of 0.3- to 0.5-μm particles ranged from 1.5 hr^?1 during operation of an in-duct, 5-in. pleated media filter to 7.2 hr^?1 for an in-duct electrostatic air cleaner in comparison to a baseline rate of 0 hr^?1 when the air handler was operating without a filter. Removal rates for total particulate matter less than 2.5 μm in aerodynamic diameter (PM_2.5) mass concentrations were 0.5 hr^?1 under baseline conditions, 0.5 hr^?1 during operation of three portable ionic air cleaners, 1 hr^?1 for an in-duct 1-in. media filter, 2.4 hr^?1 for a single high-efficiency particle arrestance (HEPA) portable air cleaner, 4.6 hr^?1 for an in-duct 5-in. media filter, 4.7 hr^?1 during operation of five portable HEPA filters, 6.1 hr^?1 for a conventional in-duct electronic air cleaner, and 7.5 hr^?1 for a high efficiency in-duct electrostatic air cleaner. Corresponding whole house clean air delivery rates for PM_2.5 attributable to the air cleaner independent of losses within the central ventilation system ranged from 2 m³/min for the conventional media filter to 32 m³/min for the high efficiency in-duct electrostatic device. Except for the portable ionic air cleaner, the devices considered here increased particle removal indoors over baseline deposition rates.     

Understanding the patterns and mechanisms of urban water ecosystem degradation: phytoplankton community structure and water quality in the Qinhuai River, Nanjing City, China

The temporal and spatial distribution characteristics of environmental parameters and the phytoplankton community were investigated in October 2010 and January 2011 in the Qinhuai River, Nanjing, China. Results showed that the water quality in the study area was generally poor, and the main parameters exceeding standards (level V) were nitrogen and phosphorus. The observed average concentrations of the total nitrogen (TN) were 4.90 mg?L^?1 in autumn and 9.29 mg?L^?1 in winter, and those of the total phosphorus (TP) were 0.24 mg?L^?1 in autumn and 0.88 mg?L^?1 in winter, respectively. Thirty-seven species, 30 genera, and four phyla of phytoplankton were detected in the river. Cyanophyta and Bacillariophyta were the dominant phyla in autumn, with average abundance and biomass of 221.5?×?10⁴?cells?L^?1 and 4.41 mg?L^?1, respectively. The dominant population in winter was Bacillariophyta, and the average abundance and biomass were 153.4?×?10⁴?cells?L^?1 and 6.58 mg?L^?1, respectively. The results of canonical correspondence analysis (CCA) between environmental parameters and phytoplankton communities showed that Chlorophyta could tolerate the higher concentrations of the permanganate index, nitrogen, and phosphorus in eutrophic water; Bacillariophyta could adapt well to changing water environments; and the TN/TP ratio had obvious impacts on the distributions of Cyanophyta, Euglenophyta, and some species of Chlorophyta. CCA analyses for autumn and winter data revealed that the main environmental parameters influencing phytoplankton distribution were water temperature, conductivity, and total nitrogen, and the secondary factors were dissolved oxygen, NH₄ ⁺–N, NO₃–N, TN, COD_Mn, TN/TP ratio, and oxidation-reduction potential.     

Ammonia concentrations and modeling of inorganic particulate matter in the vicinity of an egg production facility in Southeastern USA

Ammonia (NH₃) is an important base gas and can react with acidic species to form atmospheric aerosols. Due to the rapid growth of poultry and swine production in the North Carolina Coastal Plain, atmospheric NH₃ concentrations across the region have subsequently increased. Ammonia concentrations and inorganic particulate matter (PM) at four ambient stations in the vicinity of an egg production facility were measured for 1 year using PM_2.5 speciation samplers with honeycomb denuders and ion chromatography (IC). Meanwhile, concentrations of NH₃ and inorganic PM in one of the egg production houses were also simultaneously measured using a gas analyzer for NH₃ and the filter pack plus IC method for inorganic PM. An equilibrium model-ISORROPIA II was applied to predict the behavior of inorganic aerosols in response to precursor gas concentrations and environmental parameters. Average ambient NH₃ concentrations varied from 10.0 to 27.0 μg/m³, and they were negatively correlated with the distances from the ambient location to the nearest egg production house exhausts. Ambient NH₃ concentrations were higher in warm seasons than in cold seasons. Measured NH₃ concentrations agreed well with ISORROPIA II model predictions at all sampling stations. For the ambient stations, there was a good agreement in particle phase NH₄ ⁺ between the model simulation and observations. For the in-house station, the model simulation was applied to correct the overestimation of particle phase NH₄ ⁺ due to gas phase NH₃ breaking through the denuders. Changes in SO₄ ^2?, NO₃ ^?, and Cl^? yield proportional changes in inorganic PM mass. Due to the abundance of NH₃ gas in the vicinity area of the monitored farm, changes in NH₃ concentrations had a small effect on inorganic PM mass. Aerosol equilibrium modeling may be used to assess the influence of precursor gas concentrations on inorganic PM formation when the measurements for some species are unavailable.     

The characterization of water-soluble inorganic ions in PM2.5 during a winter period in Xi'an,China

The characteristics of water-soluble inorganic ions (WSIIs) during a winter period in a suburb of Xi'an, China, were investigated. Our results show that the total mass concentration of the dominant WSIIs (8) was 91.27 µg m^–3, accounting for 50.1% of the total mass concentration of PM_2.5 (particulates with a size of 2.5 µm or less). Secondary inorganic aerosols (SO₄^2?, NO₃^? and NH₄⁺) were the most abundant ions, accounting for up to 95.12% of the total ions. By using the anion and cation equivalence ratio method, PM_2.5 was shown to have weak alkalinity, and the chemical forms of WSIIs were mainly (NH₄)₂SO₄ and NH₄NO₃. The sulfur oxidation ratio (SOR) and nitrogen oxidation ratio (NOR) suggested that larger proportions of SO₄^2? and NO₃^? were formed by gas-phase SO₂ and NO₂ in the sampling site. Ratio analysis also indicated that anthropogenic sources significantly contributed to WSII pollution. Among the anthropogenic sources, fixed pollution sources were found to be dominant over mobile sources.     

Temporal variations of atmospheric aerosol in four European urban areas

Purpose

The concentrations of PM₁₀ mass, PM_2.5 mass and particle number were continuously measured for 18 months in urban background locations across Europe to determine the spatial and temporal variability of particulate matter.

Methods

Daily PM₁₀ and PM_2.5 samples were continuously collected from October 2002 to April 2004 in background areas in Helsinki, Athens, Amsterdam and Birmingham. Particle mass was determined using analytical microbalances with precision of 1 ??g. Pre- and post-reflectance measurements were taken using smoke-stain reflectometers. One-minute measurements of particle number were obtained using condensation particle counters.

Results

The 18-month mean PM₁₀ and PM_2.5 mass concentrations ranged from 15.4 ??g/m³ in Helsinki to 56.7 ??g/m³ in Athens and from 9.0 ??g/m³ in Helsinki to 25.0 ??g/m³ in Athens, respectively. Particle number concentrations ranged from 10,091 part/cm³ in Helsinki to 24,180 part/cm³ in Athens with highest levels being measured in winter. Fine particles accounted for more than 60% of PM₁₀ with the exception of Athens where PM_2.5 comprised 43% of PM₁₀. Higher PM mass and number concentrations were measured in winter as compared to summer in all urban areas at a significance level p?Conclusions Significant quantitative and qualitative differences for particle mass across the four urban areas in Europe were observed. These were due to strong local and regional characteristics of particulate pollution sources which contribute to the heterogeneity of health responses. In addition, these findings also bear on the ability of different countries to comply with existing directives and the effectiveness of mitigation policies.     

Effects of nitrogen application rate and a nitrification inhibitor dicyandiamide on methanotroph abundance and methane uptake in a grazed pasture soil

Methane-oxidizing bacteria (methanotrophs) in the soil are a unique group of methylotrophic bacteria that utilize methane (CH₄) as their sole source of carbon and energy which limit the flux of methane to the atmosphere from soils and consume atmospheric methane. A field experiment was conducted to determine the effect of nitrogen application rates and the nitrification inhibitor dicyandiamide (DCD) on the abundance of methanotrophs and on methane flux in a grazed pasture soil. Nitrogen (N) was applied at four different rates, with urea applied at 50 and 100 kg N ha^?1 and animal urine at 300 and 600 kg N ha^?1. DCD was applied at 10 kg ha^?1. The results showed that both the DNA and selected mRNA copy numbers of the methanotroph pmoA gene were not affected by the application of urea, urine or DCD. The methanotroph DNA and mRNA pmoA gene copy numbers were low in this soil, below 7.13?×?10³ g^?1 soil and 3.75?×?10³ μg^?1 RNA, respectively. Daily CH₄ flux varied slightly among different treatments during the experimental period, ranging from ?12.89 g CH₄ ha^?1 day^?1 to ?0.83 g CH₄ ha^?1 day^?1, but no significant treatment effect was found. This study suggests that the application of urea fertilizer, animal urine returns and the use of the nitrification inhibitor DCD do not significantly affect soil methanotroph abundance or daily CH₄ fluxes in grazed grassland soils.     

Nitrate facilitates cadmium uptake, transport and accumulation in the hyperaccumulator Sedum plumbizincicola

The aims of this study are to investigate whether and how the nitrogen form (nitrate (NO₃ ^–) versus ammonium (NH₄ ⁺)) influences cadmium (Cd) uptake and translocation and subsequent Cd phytoextraction by the hyperaccumulator species Sedum plumbizincicola. Plants were grown hydroponically with N supplied as either NO₃ ^– or NH₄ ⁺. Short-term (36 h) Cd uptake and translocation were determined innovatively and quantitatively using a positron-emitting ¹⁰⁷Cd tracer and positron-emitting tracer imaging system. The results show that the rates of Cd uptake by roots and transport to the shoots in the NO₃ ^– treatment were more rapid than in the NH₄ ⁺ treatment. After uptake for 36 h, 5.6 (0.056 μM) and 29.0 % (0.290 μM) of total Cd in the solution was non-absorbable in the NO₃ ^– and NH₄ ⁺ treatments, respectively. The local velocity of Cd transport was approximately 1.5-fold higher in roots (3.30 cm h^?1) and 3.7-fold higher in shoots (10.10 cm h^?1) of NO₃ ^–- than NH₄ ⁺-fed plants. Autoradiographic analysis of ¹⁰⁹Cd reveals that NO₃ ^– nutrition enhanced Cd transportation from the main stem to branches and young leaves. Moreover, NO₃ ^– treatment increased Cd, Ca and K concentrations but inhibited Fe and P in the xylem sap. In a 21-day hydroponic culture, shoot biomass and Cd concentration were 1.51 and 2.63 times higher in NO₃ ^–- than in NH₄ ⁺-fed plants. We conclude that compared with NH₄ ⁺, NO₃ ^– promoted the major steps in the transport route followed by Cd from solution to shoots in S. plumbizincicola, namely its uptake by roots, xylem loading, root-to-shoot translocation in the xylem and uploading to the leaves. S. plumbizincicola prefers NO₃ ^– nutrition to NH₄ ⁺ for Cd phytoextraction.