Spatial and diel variability in the emissions of some biogenic sulfur compounds from a Florida Spartinaalterniflora coastal zone

Emission rates of the biogenic reduced sulfur gases dimethyl sulfide, dimethyl disulfide, carbon disulfide and hydrogen sulfide were measured from several environments within a Florida Spartina alterniflora coastal zone. Spatial and diel variability was observed in the emission rates of all the sulfur gases. The speciation and magnitude of sulfur emissions can be related to site elevation and the spatial variability of vegetation coverage. Dimethyl sulfide appears to be a metabolic byproduct of S. alterniflora.     

Emission of volatile organic sulfur compounds (VOSCs) during aerobic decomposition of food wastes

Food wastes collected from typical urban residential communities were investigated for the emission of volatile organic sulfur compounds (VOSCs) during laboratory-controlled aerobic decomposition in an incubator for a period of 41 days. Emission of VOSCs from the food wastes totaled 409.9 mg kg^?1 (dry weight), and dimethyl disulfide (DMDS), dimethyl sulfide (DMS), methyl 2-propenyl disulfide, carbonyl sulfide and methyl 1-propenyl sulfide were the five most abundant VOSCs, with shares of 75.5%, 13.5%, 4.8%, 2.2% and 1.3% in total 15 VOSCs released, respectively. The emission fluxes of major VOSCs were very low at the beginning (day 0). They peaked at days 2–4 and then decreased sharply until they leveled off after 10 days of incubation. For most VOSCs, over 95% of their emission occurred in the first 10 days. The time series of VOSC emission fluxes, as well as their significant correlation with internal food waste temperature (p < 0.05) during incubation, suggested that production of VOSC species was induced mainly by microbial activities during the aerobic decomposition instead of as inherited. Released VOSCs accounted for 5.3% of sulfur content in the food wastes, implying that during aerobic decomposition considerable portion of sulfur in food wastes would be released into the atmosphere as VOSCs, primarily as DMDS, which is very short-lived in the atmosphere and thus usually less considered in the sources and sinks of reduced sulfur gases.     

Sulfur Gas Emissions from Flue Gas Desulfurization Sludge Ponds

This paper presents initial measurement data on the emission of volatile, reduced sulfur-containing gases from flue gas desulfurization (FGD) storage ponds. Several different types of FGD stored sludges were studied including lime, limestone, and mixtures of fly ash and lime or limestone residues, some of which had been chemically stabilized. The volatile sulfur gas emissions were cryogenically concentrated and determined by wall-coated, open-tubular capillary column gas chromatography using a flame photometric detector. Hydrogen sulfide, carbonyl sulfide, dimethyl sulfide, carbon disulfide, and an unusual, unidentified sulfur-containing compound were found in the gaseous pond flux. Benzene, toluene, and α-pinene were also identified by gas chromatography-single ion monitoring mass spectrometry. The total reduced sulfur gas emission from a 100 acre pond approximated 2.0 kg day^?1 (as sulfur).     

Sulfur Gas Emissions From Stored Flue Gas Desulfurization Sludges

The emissions of volatile sulfur-containing compounds from 13 flue gas desulfurization (FGD) sludge field storage sites have been characterized. Sulfur gas emissions from the sludge surfaces were determined by measuring the sulfur gas enhancement of sulfur-free sweep air passing through a dynamic emission flux chamber placed over selected sampling sites. Samples of the enclosure sweep air were cryogenically concentrated in surface-deactivated Pyrex “U” traps. Analyses were conducted by wall-coated, open-tubular, capillary column, cyrogenic gas chromatography using a sulfur-selective, flame photometric detector. Several major variables associated with FGD sludge production processes were examined in relation to the measured range and variations in sulfur fluxes including: (a) the sulfur dioxide scrubbing reagent used, (b) sludge sulfite oxidation, (c) “unfixed” or “fixed” FGD sludge, and (d) ponding or landfill storage. The composition and concentration of the measured sulfur gas emissions were found to vary with the type of sludge, the effectiveness of rainwater drainage from the landfill surface, the method of impoundment, and the sulfate/sulfite ratio of the sludge. Hydrogen sulfide, carbonyl sulfide, dimethyl sulfide, carbon disulfide, and dimethyl disulfide were identified in varying concentrations and ratios in the FGD sludge emissions. In addition, up to four unidentified organo- sulfur compounds were found in the emissions from four FGD sludges. The sulfur flux from one FGD storage pond was analyzed by gas chromatography-single ion monitoring mass spectrometry. In addition to the four identified sulfur compounds, this flux contained large concentrations of benzene, toluene, and α-pinene. The measured, total sulfur emissions ranged from less than 0.01 to nearly 0.3 kg of sulfur per day for an equivalent 100 acre (40.5 hectare) sludge impoundment surface.     

A study of volatile organic sulfur emissions causing urban odors

Levels of hydrogen sulfide and sulfur containing organic compounds were studied in the air at the deltas of the polluted creeks in the city of Izmir, Turkey in summer 2001. High concentrations of these malodorous compounds were measured in the air samples. Presence of these compounds in the air was connected with the dark appearance and rising gas bubbles in the studied segments of the creeks. These creeks were like open sewers carrying wastewaters from the industry and residential areas into the inner Izmir Bay until September 2001.Within the scope of this study organic sulfur compounds such as methane thiol, ethane thiol, 2-propane thiol, 2-butane thiol, dimethylsulfide, dimethyldisulfide, thiophene, diphenylsulfide and hydrogen sulfide were studied in the air at selected urban sites where odor nuisance was recognized. Flux measurements from polluted surfaces were preferred rather than direct ambient air measurements. Organic sulfur emission fluxes from the creek surfaces were found above the values reported in the literature. Their concentrations and fluxes were higher in June field program. A limited number of measurements of reduced sulfur compound emission concentrations from the wastewater treatment plant equalization tank and the sludge drying beds as well as the landfill soil surface were also included in the study.Concentrations of total organic sulfur compounds and certain individual components such as dimethylsulfide and hydrogen sulfide in emitted gases from river surfaces were correlated with ambient SO(2) concentrations.     

Short-term variability in biogenic sulphur emissions from a florida spartina alterniflora marsh

Emissions of biogenic sulphur gases from a Florida Spartina alterniflora zone were measured over several tidal and diel cycles using a dynamic flow chamber technique, corroborating recently published information in the literature. The flux of hydrogen sulfide from individual measurements is shown to vary by over four orders of magnitude, and correlates primarily with the stage of the tidal cycle. In contrast, the fluxes of dimethyl sulphide, carbon disulphide and dimethyl disulphide vary by less than an order of magnitude and correlate primarily with the diurnal temperature changes in the sediment surface. These differences are discussed in terms of the various biological and physical parameters which may regulate the release of reduced sulphur compounds to the atmosphere.     

Isoprene and monoterpene fluxes measured above Amazonian rainforest and their dependence on light and temperature

Canopy scale emissions of isoprene and monoterpenes from Amazonian rainforest were measured by eddy covariance and eddy accumulation techniques. The peak mixing ratios at about 10 m above the canopy occurred in the afternoon and were typically about 90 ppt_v of α-pinene and 4–5 ppb_v of isoprene. α-pinene was the most abundant monoterpene in the air above the canopy comprising ≈50% of the total monoterpene mixing ratio. Measured isoprene fluxes were almost 10 times higher than α-pinene fluxes. Normalized conditions of 30°C and 1000 μmol m⁻² s⁻¹ were associated with an isoprene flux of 2.4 mg m⁻² h⁻¹ and a β-pinene flux of 0.26 mg m⁻² h⁻¹. Both fluxes were lower than values that have been specified for Amazon rainforests in global emission models. Isoprene flux correlated with a light- and temperature-dependent emission activity factor, and even better with measured sensible heat flux. The variation in the measured α-pinene fluxes, as well as the diurnal cycle of mixing ratio, suggest emissions that are dependent on both light and temperature. The light and temperature dependence can have a significant effect on the modeled diurnal cycle of monoterpene emission as well as on the total monoterpene emission.     

Sulfuric odorous compounds emitted from pig-feeding operations

The objective of the study was to quantify the concentration and emission levels of sulfuric odorous compounds emitted from pig-feeding operations. Five types of pig-housing rooms were studied: gestation, farrowing, nursery, growing and fattening rooms. The concentration range of sulfuric odorous compounds in these pig-housing rooms were 30–200 ppb for hydrogen sulfide (H₂S), 2.5–20 ppb for methyl mercaptan (CH₃SH), 1.5–12 ppb for dimethyl sulfide (DMS; CH₃SCH₃) and 0.5–7 ppb for dimethyl disulfide (DMDS; CH₃S₂CH₃), respectively. The emission rates of H₂S, CH₃SH, DMS and DMDS were estimated by multiplying the average concentration (mg m⁻³) measured near the air outlet by the mean ventilation rate (m³ h⁻¹) and expressed either per area (mg m⁻² h⁻¹) or animal unit (AU; liveweight of the pig, 500 kg) (mg pig⁻¹ h⁻¹). As a result, the emission rates of H₂S, CH₃SH, DMS and DMDS in the pig-housing rooms were 14–64, 0.8–7.3, 0.4–3.4 and 0.2–1.9 mg m⁻² h⁻¹, respectively, based on pig's activity space and 310–723, 18–80, 9–39 and 5–22 mg AU⁻¹ h⁻¹, respectively, based on pig's liveweight, which indicates that their emission rates were similar, whether based upon the pig's activity space or liveweight. In conclusion, the concentrations and emission rates of H₂S were highest in the fattening room followed by the growing, nursery, farrowing and gestation rooms whereas those of CH₃SH, DMS and DMDS concentrations were largest in the growing room followed by the nursery, gestation and farrowing rooms.     

Emissions of biogenic sulphur compounds from several wetland soils in Florida

Emission rates of the biogenic sulphur gases hydrogen sulphide, dimethyl sulphide, carbon disulphide and dimethyl disulphide have been measured from the exposed soils of five wetland plant communities in Florida. Dimethyl sulphide and hydrogen sulphide were the predominant species emitted. All the studied ecosystems showed diel variation in the emission rates of the biogenic sulphur gases with the highest emissions rates occurring early- to mid-afternoon, and the lowest emission rates occurring during the early morning. The relative magnitude of emissions from the individual ecosystems followed the trend Distichlis spicata >Avicennia germinans >Batis maritima ≅ Juncus roemerianus ≅ Cladium jamaicense. Only the emission rates from the peaty D. spicata site are comparable in magnitude to previous emission measurements in wetland ecosystems of Spartina alterniflora and associated mud flats.     

Seasonal variations in VOC emission rates from gorse (Ulex europaeus)

Seasonal variations of biogenic volatile organic compound (VOC) emission rates and standardised emission factors from gorse (Ulex europaeus) have been measured at two sites in the United Kingdom, from October 1994 to September 1995, within temperature and PAR conditions ranging from 3 to 34°C and 10–1300 μmol m⁻² s⁻¹, respectively. Isoprene was the dominant emitted compound with a relative composition fluctuating from 7% of the total VOC (winter) to 97% (late summer). The monoterpenes α-pinene, camphene, sabinene, β-pinene, myrcene, limonene, trans-ocimene and γ-terpinene were also emitted, with α-pinene being the dominant monoterpene during most the year. Trans-ocimene represented 33–66% of the total monoterpene during the hottest months from June to September. VOC emissions were found to be accurately predicted using existing algorithms. Standard (normalised) emission factors of VOCs from gorse were calculated using experimental parameters measured during the experiment and found to fluctuate with season, from 13.3±2.1 to 0.1±0.1 μg C (g dwt)⁻¹ h⁻¹ in August 1995 and January 1995, respectively, for isoprene, and from 2.5±0.2 to 0.4±0.2 μg C (g dwt)⁻¹ h⁻¹ in July and November 1995, respectively, for total monoterpenes. No simple clear relation was found to allow prediction of these seasonal variations with respect to temperature and light intensity. The effects of using inappropriate algorithms to derive VOC fluxes from gorse were assessed for isoprene and monoterpenes. Although on an annual basis the discrepancies are not significant, monthly estimation of isoprene were found to be overestimated by more than a factor of 50 during wintertime when the seasonality of emission factors is not considered.     

Atmospheric deposition of macronutrients by pollen at a semi-remote site in northern Wisconsin

Pine pollen concentrations in air at a semi-remote site in northern Wisconsin attained levels of 18 and 25 μ m⁻³ in late May and early June of 1979 and 1981, respectively. The upper and lower limits for the deposition velocity of pine pollen at this site are approximately 30 and 1.3 cm s⁻¹, respectively. Consequently, the average annual pine pollen flux at this location for 1979 and 1981 was between 8.0 and 0.35 g m⁻². Deposition of total phosphorus and organic C by pollen dispersal are about 5–100% and 11–240%, respectively, of the measured bulk atmospheric loading rate in the region. Pine pollen fluxes of water-extractable K are about 10–230% of the average annual wet deposition, while the fluxes of waterextractable NO₃⁻ and SO₄⁻² by pollen appear to be negligible in comparison to the total atmospheric deposition (wet plus dry deposition) by other particles. The annual pine pollen flux to Crystal Lake, an oligotrophic seepage lake in the region, was estimated to be 6.5 g m⁻² during 1981. The deposition of total P by pollen to this lake was 5.8 kg a⁻¹, which is 45 % of the external input of total phosphorus. About 60% of the total P in samples of Pinus strobus and P. resinosa was dissolved reactive P, which is readily available for plant uptake. Because P is the limiting nutrient for many lacustrine systems and pine pollen dispersal coincides with the period of phytoplankton blooms in temperate-region lakes, this episodic input of P may represent an important source for seepage lakes whose external inputs are dominated by atmospheric deposition.     

Atmospheric deposition of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in Guangzhou,China

Atmospheric deposition of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) was investigated at four locations, namely at Yuancun, Wushan, Haizhu and Changban in Guangzhou City, Guangdong Province. The annual deposition fluxes of tetra- to octa-CDD/Fs (total PCDD/Fs) were found to range from 170 to 3000 (mean 1500) pg m⁻² day⁻¹, and the fluxes of total 2, 3, 7, 8-substituted PCDD/F congeners ranged from 2.1 to 41 (mean 20) pg WHO-TEQ m⁻² day⁻¹ at Wushan. The average deposition fluxes of total 2, 3, 7, 8-substituted PCDD/F congeners in rainy season were found to be 37, 27 and 28 pg WHO-TEQ m⁻² day⁻¹ at Yuancun, Haizhu and Changban, respectively, and the PCDD/F deposition fluxes behaved obviously higher in rainy season than in dry season. Results from regression analysis showed that number of rainy days, the amount of wet precipitation, PCDD/F concentrations in particles and organic carbon content played important roles in the variation of PCDD/F deposition fluxes. Monthly average temperatures change little over the year. Therefore, it only played a minor role in monthly variation of PCDD/F deposition fluxes. Particle deposition fluxes were generally not considered as the factor that could cause the differences in PCDD/F deposition fluxes between rainy and dry season, but were found to be related with PCDD/F deposition fluxes in rainy season or dry season. It was found that the profiles of PCDD/F homologs or congeners in the samples were the same either spatially or temporally, indicating that the PCDD/F emission sources were similar to one another. The similarities in PCDD/F homolog patterns and the differences in deposition fluxes between samples collected from heavy-traffic roadside and nearby residence house roof indicated that vehicle exhaust might be an important source for PCDD/F in Guangzhou. PCDD/F concentrations and profiles of PCDD/F homologs in atmospheric deposition were compared with those in both total suspended particles in air and soils, and conclusions indicated that atmospheric deposition possibly tended to remove lower-chlorinated DD/Fs from air and was one of sources for PCDD/Fs in soils.     

Characterization of odor released during handling of swine slurry: Part I. Relationship between odorants and perceived odor concentrations

Odor emission from livestock production systems is a major nuisance in many rural areas. This study aimed at determining the major airborne chemical compounds responsible for the unpleasant odor perceived in swine facilities during slurry handling, and at proposing predictive models of odor concentration (OC) based on the concentrations of specific odorants in the air. A multivariate data analysis strategy involving principal components analysis and multiple linear regressions was implemented to analyze the relationships between concentration of 35 gases (measured by GC/MS or gas detection tubes), and the overall OC perceived by sensory analysis. The study compiled data on the concentration of odor and odorants, measured in the headspace of 24 unstored and stored slurry samples collected from three different types of production units on 8 commercial swine farms. Among all the measured constituents, OC was found to have the highest correlation with the sulfur containing compounds (i.e. hydrogen sulfide, dimethylsulfide, dimethyldisulfide, dimethyltrisulfide). The concentration of hydrogen sulfide accounted for 68% of the variation in OC above the stirred slurry samples. The highest concentrations of volatile organic compounds were observed for phenols and indoles, which made a significant contribution to the overall OC when the slurry was fresh. The contribution of ammonia to the OC was only significant in the absence of hydrogen sulfide. The precision of predictive models of OC based on the concentration of specific odorants in the air was satisfactory (R² between 0.66 and 0.89). Hence, this study suggests that monitoring of specific odor compounds released from agitated swine slurry can be used to predict the concentration of odor perceived close to the source (e.g. at storage units), allowing the assessment of odor nuisance potentials.     

Formation of particulate sulfur species (sulfate and methanesulfonate) during summer over the Eastern Mediterranean: A modelling approach

To improve our understanding of the mechanisms of particulate sulfur formation (non sea-salt sulfate, nss-SO₄²⁻) and methanesulfonate (MS_x used here to represent the sum of gaseous methanesulfonic acid, MSA, and particulate methanesulfonate, MS⁻) in the eastern Mediterranean and to evaluate the relative contribution of biogenic and anthropogenic sources to the S budget, a chemical box model coupled offline with an aerosol–cloud model has been used.Based on the measurements of gaseous dimethyl sulfide (DMS) and methanesulfonic acid (MSA) and the MSA sticking coefficient determined during the Mediterranean Intensive Oxidant Study (MINOS) experiment, the yield of gaseous MSA from the OH-initiated oxidation of DMS was calculated to be about 0.3%. Consequently, MSA production from gas-phase oxidation of DMS is too small to explain the observed levels of MS⁻. On the other hand, heterogeneous reactions of dimethyl sulfoxide (DMSO) and its gas-phase oxidation product methanesulfinic acid (MSIA) can account for most of the observed MS⁻ levels. The modelling results indicate that about 80% of the production of MS⁻ can be attributed to heterogeneous reactions.Observed submicron nss-SO₄²⁻ levels can be fully explained by homogeneous (photochemical) gas-phase oxidation of sulfur dioxide (SO₂) to sulfuric acid (H₂SO₄), which is subsequently scavenged by (mainly submicron) aerosol particles. The predominant oxidant during daytime is hydroxyl radical (OH) showing very high peak levels in the area during summer mostly under cloudless conditions. Therefore, during summer in the east Mediterranean, heterogeneous sulfate production appears to be negligible. This result is of particular interest for sulfur abatement strategy. On the other hand only about 10% of the supermicron nss-SO₄²⁻ can be explained by condensation of gas-phase H₂SO₄, the rest must be formed via heterogeneous pathways.Marine biogenic sulfur emissions contribute up to 20% to the total oxidized sulfur production (SO₂ and H₂SO₄) in good agreement with earlier estimates for the area.     

Characteristic analysis for odor gas emitted from food waste anaerobic fermentation in the pretreatment workshop

Gas chromatography–mass spectrometry, olfactometry, and other related methods were applied for the qualitative and quantitative analysis of the characteristics of odorous gases in the pretreatment workshop. The composition of odorous gases emitted from municipal food waste was also investigated in this study. The results showed that the tested gases are mainly composed of aromatic gases, which account for 49% of the total volatile organic compounds (VOC) concentrations. The nitrogenous compounds comprise 15% of the total concentration and the other gases comprise the remaining 36%. The level of odor concentration ranged from 2523 odor units (OU) m^?3 to 3577 OU m^?3. The variation of the total chemical composition ranged from 19,725 µg m^?3 to 24,184 µg m^?3. Among the selected four sampling points, the discharge outlet was detected to have the highest concentration in terms of odor, total chemical, sulfur compounds, and aromatics. The correlation analysis showed that the odor concentrations were evidently related to the total chemical composition, sulfur compounds, and aromatics (P < 0.05, n = 5). The odor activity value analysis identified the top three compounds, hydrogen sulfide (91.8), ethyl sulfide (35.8), and trimethylamine (70.6), which contribute to air pollution complaint of waste materials.

Implications: Currently, the amount of food waste has rapidly increased, which leads to difficulty in waste management and more odorous gases released as air pollution. In processing of food wastes by anaerobic fermentation, odorous gases are generated, which significantly affect the workers and occupants in the plant. In the pretreatment workshop for anaerobic decomposition, the odorous gases are generated because of the stacking and decomposition of food wastes. The gases emitted mainly consist of organic gases because the food wastes are mainly organic materials. The other odors that comprise 1% of the gases are S-compounds, aromatics, esters, alkanes, and limonene, which result in unpleasant odors that are harmful to the health.     

Nitrous oxide emissions from mineral and organic soils of a Norway spruce stand in South–West Germany

Due to the high temporal and spatial variability of N₂O fluxes, estimates of N₂O emission from temperate forest ecosystems are still highly uncertain, particularly at larger scales. Although highest N₂O emissions with up to 7.0 kg N ha⁻¹ yr⁻¹ were mainly reported for soils affected by stagnant water, most of the reported gas flux measurements were performed at forest sites with well-aerated soils yielding mostly to low mean annual emission rates less than 1.0 kg N ha⁻¹ yr⁻¹. This study compares N₂O fluxes from upland (Cambisols) and temporally water-logged (Gleysols, Histosols) soils of the Central Black Forest (South-West Germany) over a period of 2 yr. Mean annual N₂O fluxes from investigated soils ranged between 0.2 and 3.9 kg N ha⁻¹ yr⁻¹. The fluxes showed a large variability between the different soil types. Emissions could be clearly ranked in the following order: Cambisols (0.26–0.75 kg N ha⁻¹ yr⁻¹)<Gleysols (1.37–2.68 kg N ha⁻¹ yr⁻¹)<Histosol (3.66–3.95 kg N ha⁻¹ yr⁻¹). Although the Cambisols cover two-thirds of the investigated area, only about half of the overall N₂O is emitted from this soil type. Therefore, regional or national N₂O fluxes from temperate forest soils are underestimated if soils characterised by intermediate aeration conditions are disregarded.     

Carbonyl sulfide,dimethyl sulfide and carbon disulfide in the Pearl River Delta of southern China: Impact of anthropogenic and biogenic sources

Reduced sulfur compounds (RSCs) such as carbonyl sulfide (OCS), dimethyl sulfide (DMS) and carbon disulfide (CS₂) impact radiative forcing, ozone depletion, and acid rain. Although Asia is a large source of these compounds, until now a long-term study of their emission patterns has not been carried out. Here we analyze 16 months of RSC data measured at a polluted rural/coastal site in the greater Pearl River Delta (PRD) of southern China. A total of 188 canister air samples were collected from August 2001 to December 2002. The OCS and CS₂ mixing ratios within these samples were higher in autumn/winter and lower in summer due to the influence of Asian monsoon circulations. Comparatively low DMS values observed in this coastal region suggest a relatively low biological productivity during summer months. The springtime OCS levels in the study region (574 ± 40 pptv) were 25% higher than those on other East Asia coasts such Japan, whereas the springtime CS₂ and DMS mixing ratios in the PRD (47 ± 38 pptv and 22 ± 5 pptv, respectively) were 3–30 times lower than elevated values that have been measured elsewhere in East Asia (Japan and Korea) at this time of year. Poor correlations were found among the three RSCs in the whole group of 188 samples, suggesting their complex and variable sources in the region. By means of backward Lagrangian particle release simulations, air samples originating from the inner PRD, urban Hong Kong and South China Sea were identified. The mean mixing ratio of OCS in the inner PRD was significantly higher than that in Hong Kong urban air and South China Sea marine air (p < 0.001), whereas no statistical differences were found for DMS and CS₂ among the three regions (p > 0.05). Using a linear regression method based on correlations with the urban tracer CO, the estimated OCS emission in inner PRD (49.6 ± 4.7 Gg yr^?1) was much higher than that in Hong Kong (0.32 ± 0.05 Gg yr^?1), whereas the estimated CS₂ and DMS emissions in the study region accounted for a very few percentage of the total CS₂ and DMS emission in China. These findings lay the foundation for better understanding sulfur chemistry in the greater PRD region of southern China.     

Isoprene and monoterpene emission from the coniferous species Abies Borisii-regis—implications for regional air chemistry in Greece

The emission of isoprene has been studied from a forest of Abies Borisii-regis, a Mediterranean fir species previously thought to emit only monoterpenes. Emission studies from two independent enclosure experiments indicated a standardised isoprene emission rate of (18.4±3.8) μg g_dry-weight⁻¹ h⁻¹, similar in magnitude to species such as eucalyptus and oak which are considered to be strong isoprene emitters. Isoprene emission depended strongly on both leaf temperature (2°C–34°C) and photosynthetically active radiation (PAR) below 250 μmol m⁻² s⁻¹, becoming saturated with respect to PAR above this value. The annual isoprene emission rate was estimated to be (132±29) kT yr⁻¹ for those trees growing within Greece, comparable to current estimates of the total isoprene budget of Greece as a whole, and contributing significantly to regional ozone and carbon monoxide budgets. Monoterpene emission exhibited exponential temperature dependence, with 1,8-cineole, α-pinene, β-pinene and limonene forming the primary emissions. A standardised total monoterpene emission rate of (2.7±1.1) μg g_dry-weight⁻¹ h⁻¹ was calculated, corresponding to an annual monoterpene emission rate of (24±12) kT yr⁻¹. Research was conducted as part of the AEROBIC’97 (AEROsol formation from BIogenic organic Carbon) series of field campaigns.     

Methane emissions from an anaerobic swine lagoon

Gaseous methane (CH₄) emissions from a swine waste holding lagoon were determined periodically during the year. Micrometeorological techniques were used in order that emission rates from the lagoon were measured under ambient conditions with little disturbance to the natural environment. During the cold winter measurement period, CH₄ fluxes were linearly related to lagoon water temperature below 22°C (r=0.87). During warmer measurement periods, both water and air temperatures and windspeed affected emissions rates. In general, flux rates followed a diurnal pattern with greater fluxes during the day when both temperature and windspeed were greatest. Mathematical models using air and water temperature and windspeed factors could explain 47 to 75% of the variation in fluxes. Daily emission rates ranged from 1 to 500 kg CH₄ ha⁻¹ d⁻¹. The average flux for the year was 52.3 kg CH₄ ha⁻¹ d⁻¹ which corresponded to about 5.6 kg CH₄ animal⁻¹ yr⁻¹ from the primary lagoon.     

Components and dispersion characteristics of organic and inorganic odorous gases in a large-scale dairy farm

The rapid development of large-scale livestock husbandry has caused serious air pollution problems (e.g., The Tuzuoqi demonstration farm belonging to the Yili Group. The farm is located in the suburb of Hohhot City in northern China). In this study, the gases in typical areas of a large-scale dairy farm were sampled and measured for volatile organic compounds (VOCs), hydrogen sulfide, and ammonia concentrations. Fifty-two species of VOCs were identified. The VOCs emitted from the cowshed mainly consisted of halogenated hydrocarbons (16,960 µg/m³), ketones (15,700 µg/m³), esters (9889 µg/m³), and sulfur compounds (3677 µg/m³). The VOCs from the oxidation pond were mainly composed of halogenated hydrocarbons (21,940 µg/m³) and ketones (3589 µg/m³). The VOCs from the solid–liquid separation tank comprised halogenated hydrocarbons (32,010 µg/m³), ketones (7169 µg/m³), and sulfur compounds (1003 µg/m³). The highest concentrations of ammonia and hydrogen sulfide were obtained from the milking parlor and solid–liquid separation tank, respectively. The ammonia concentration declined gradually due to the superposition of ammonia emitted from the cowshed and milking parlor. Analysis results of the influences of distance and meteorological factors on the dispersion of ammonia and hydrogen sulfide suggested that the dilution factors decreased with increasing distance from the emission source. Within distance ranges of 0–10 and 10–25 m, the concentration dilution factors were positively correlated with wind speed and temperature but negatively correlated with humidity and atmospheric pressure. The results of our work can provide a theoretical basis for the prevention and control of odorous gases in large-scale livestock farms.

Implications: Gases in typical areas of a large-scale dairy farm were sampled, and a total of 52 species of VOCs were identified. The highest concentrations of ketones, sulfur compounds, and esters were obtained at the cowshed (15,700, 3677, and 9889 µg/m³, respectively). Within the distance ranges of 0–10 and 10–25 m, the concentration dilution factors were positively correlated with wind speed and temperature.