An Investigation of Odors and Volatile Organic Compounds Released during Composting

ABSTRACT

The emissions of odors and volatile organic compounds produced from a commercial composting operation have been studied using a laboratory-scale composting system. The composting activity of a typical commercial compost feed was followed by monitoring the composting temperature, as well as the respiratory rate. Using a controlled aeration system, the gaseous volatiles produced were tested for odors using the "dilution-to-threshold" method, as well as gas composition, as determined by gas chromatography-mass spectrometry.

The results indicated that while there may be a reasonable correlation between the release of volatile organic compounds (VOCs) and odors, care has to be taken when trying to identify offensive odors with specific chemical species. However, the data obtained suggests that offensive odors formed during commercial composting may be due to sulfurous and nitrogenous compounds, although their concentrations in the compost gases may not be very high.

The major release of VOCs occurred during the first two weeks of composting, after which the gaseous releases fell dramatically as the composting process proceeded and temperatures started to fall.     

Jumps in Euribor and the effect of ECB monetary policy announcements

The main tool that the ECB uses to influence monetary policy is through the short-term refinancing rate, a change in the short-term interest rate can in turn cause the whole yield curve to shift. In addition to central bank announcements, interbank rates such as Euribor are also influenced by, forward guidance from the ECB, various macroeconomic events, liquidity in the money markets and the perceived credit worthiness of financial institutions. Forward rates are usually used by policy makers and market practitioners to examine expectations, but options provide additional information about the uncertainty of these expectations, particularly future jump expectations. This research examines the jump characteristics of the 3-month Euribor futures contract and its corresponding futures option contracts using both a jump diffusion model with a Bernoulli jump distribution and option-implied parameters using a jump diffusion process with Poisson distribute. We find that both the Bernoulli jump analysis of historical data and implied jump diffusion model succinctly capture diffusion volatility, jumps and jump size. Using a regression analysis to examine the effect of ECB refinancing rate monetary policy announcements on the 3-month Euribor and the associated jump parameters, we find a significant relationship between ECB announcements and the probability of a jump in Euribor. Regression coefficients on the implied jump amplitude parameters suggest that the market correctly anticipates the direction of the rate announcement suggesting option-implied jump parameters can predict, to some extent, ECB announcements. However, our results also show that there is significant uncertainty before the announcements, and this implies that monetary policy communication is not having the full desired effect.     

Anaerobic degradation of five polycyclic aromatic hydrocarbons from river sediment in Taiwan

This study investigated the anaerobic degradation of five polycyclic aromatic hydrocarbons (PAHs) from Erren River sediment in southern Taiwan. The degradation rates of PAH were in the order: acenaphthene > fluorene > phenanthrene > anthracene > pyrene. The degradation rate was enhanced when the five compounds were present simultaneously in river sediment. Comparison of the PAH degradation rates under three reducing conditions showed the following order: sulfate-reducing conditions > methanogenic conditions > nitrate-reducing conditions. The addition of electron donors (acetate, lactate and pyruvate) enhanced PAH degradation under methanogenic and sulfate-reducing conditions. However, the addition of acetate, lactate or pyruvate inhibited PAH degradation under nitrate-reducing conditions. The addition of heavy metals, nonylphenol and phthalate esters (PAEs) inhibited PAH degradation. Our results show that sulfate-reducing bacteria, methanogen and eubacteria are involved in the degradation of PAH; sulfate-reducing bacteria constitute a major microbial component in PAH degradation. Of the microorganism strains isolated from the sediment samples, we found that strain ER9 expressed the greatest biodegrading ability.     

Polybrominated diphenyl ethers (PBDEs) in farmed and wild salmon marketed in the Northeastern United States

Recently, we reported on the analysis of polychlorinated biphenyls (PCBs) and chlorinated pesticides in farmed Atlantic salmon (Salmo salar) from Maine, eastern Canada, and Norway, and wild Alaskan Chinook salmon (Oncorhynchus tshawytscha). In this paper, we extend the analysis to polybrominated diphenyl ethers (PBDEs) in these samples. Total PBDE concentrations in the farmed salmon (0.4-1.4ng/g, wet weight, ww) were not significantly different from those in the wild Alaskan Chinook samples (0.4-1.2ng/g, ww), nor were significant differences found among regions. However, significant intra-regional variations in concentrations of total PBDEs and tetra-BDE 47 were observed in the salmon from the Canadian farms (p<0.01). Congener profiles were dominated by BDE-47, followed by the penta-BDEs 99 and 100. PBDE concentrations in the Canadian samples were lower than those reported two years earlier. Removal of skin resulted in no overall reduction in PBDE concentrations in our farmed salmon, and in some cases, PBDE concentrations were higher in skin-off samples. PBDEs were correlated with lipids only in the skinned samples, suggesting that there is greater accumulation and retention of PBDEs in muscle lipids than in skin-associated fat. In skin-on samples, modest correlations were observed between concentrations of PBDEs and PCBs (R(2)=0.47) and mono-ortho PCBs (R(2)=0.50), whereas PBDEs were not correlated with non-ortho PCBs.     

Bioaccumulation of polybrominated diphenyl ethers in harbor seals from the northwest Atlantic

Polybrominated diphenyl ethers (PBDEs) were analyzed in blubber of harbor seals (Phoca vitulina concolor) collected between 1991 and 2005 along the northwest Atlantic. ∑PBDE concentrations (mono- to hexa-BDEs) detected in blubber samples (n = 42) ranged from 80 to 25 720 ng g⁻¹ lw, (overall mean 2403 ± 5406 ng g⁻¹ lw). By age, mean ∑PBDE concentrations were: 3645 ± 7388, 2945 ± 5995, 1385 ± 1265, and 326 ± 193 ng g⁻¹ lw in pups, yearlings, adult males, and adult females, respectively. Unlike the trend for PCBs, no decreasing gradient from urban to rural/remote areas was observed for PBDEs in these samples, likely reflecting inputs from local sources. No significant temporal trend was observed for PBDEs in harbor seals between 1991 and 2005, although congener profiles shifted over time. Tetra-BDE-47 was the dominant congener, followed by BDEs-99, -100, -153, -154, and -155 in varying order, suggesting exposure to the penta-BDE product. In adult males, the hexa-BDEs contributed more to the total (22%) than BDEs-99 and -100 (14%), and concentrations of BDE-155 were elevated compared with -154. Higher BDEs were detected in a subset of seals (n = 12) including hepta-BDE-183, the marker for the octa-BDE mixture, and octa-BDE-197, along with several unidentified hepta- and octa- congeners. BDE-209 was detected in seal blubber at concentrations ranging from 1.1 to 8 ng g⁻¹ lw, indicating that deca-BDE is bioavailable in this marine food web. This is the first study to document the accumulation of BDE-209 at measurable levels in wild harbor seals. While the PBDE patterns in blubber indicate exposure to all three BDE commercial mixtures, the data also suggest that BDE-209 debromination by seal prey fish may contribute to the loading of lower brominated congeners (hexa- to octa-BDEs) in these seals.     

Impact of clouds and aerosols on ozone production in Southeast Texas

A radiative transfer model and photochemical box model are used to examine the effects of clouds and aerosols on actinic flux and photolysis rates, and the impacts of changes in photolysis rates on ozone production and destruction rates in a polluted urban environment like Houston, Texas. During the TexAQS-II Radical and Aerosol Measurement Project the combined cloud and aerosol effects reduced j(NO₂) photolysis frequencies by nominally 17%, while aerosols reduced j(NO₂) by 3% on six clear sky days. Reductions in actinic flux due to attenuation by clouds and aerosols correspond to reduced net ozone formation rates with a nearly one-to-one relationship. The overall reduction in the net ozone production rate due to reductions in photolysis rates by clouds and aerosols was approximately 8 ppbv h^?1.     

Heterogeneous conversion of nitric acid to nitrous acid on the surface of primary organic aerosol in an urban atmosphere

Nitrous acid (HONO), nitric acid (HNO₃), and organic aerosol were measured simultaneously atop an 18-story tower in Houston, TX during August and September of 2006. HONO and HNO₃ were measured using a mist chamber/ion chromatographic technique, and aerosol size and chemical composition were determined using an Aerodyne quadrupole aerosol mass spectrometer. Observations indicate the potential for a new HONO formation pathway: heterogeneous conversion of HNO₃ on the surface of primary organic aerosol (POA). Significant HONO production was observed, with an average of 0.97 ppbv event^?1 and a maximum increase of 2.2 ppb in 4 h. Nine identified events showed clear HNO₃ depletion and well-correlated increases in both HONO concentration and POA-dominated aerosol surface area (SA). Linear regression analysis results in correlation coefficients (r²) of 0.82 for HONO/SA and 0.92 for HONO/HNO₃. After correction for established HONO formation pathways, molar increases in excess HONO (HONO_excess) and decreases in HNO₃ were nearly balanced, with an average HONO_excess/HNO₃ value of 0.97. Deviations from this mole balance indicate that the residual HNO₃ formed aerosol-phase nitrate. Aerosol mass spectral analysis suggests that the composition of POA could influence HONO production. Several previously identified aerosol-phase PAH compounds were enriched during events, suggesting their potential importance for heterogeneous HONO formation.     

Direct and indirect hydrological controls on E. coli concentration and loading in midwestern streams

This study investigates hydrological controls on E. coli concentration and loading in two artificially drained agricultural watersheds (58 and 23 km(2)) of the U.S. Midwest. Stream E. coli concentrations are significantly (p < 0.02) lower at base flow than high flow; however, E. coli load is significantly higher at high flow than at low flow (p < 0.001). Although E. coli concentrations are not significantly higher (p = 0.253) in summer/fall (3269 MPN/100 mL) than in the winter/spring (2411 MPN/100 mL), E. coli load is significantly higher (p < 0.05) in winter/spring (346 MPN/day) than in summer/fall season (75 MPN/day). Correlation analysis indicates that discharge and precipitation are the best indicators of E. coli concentration and 7-d antecedent precipitation (7dP), the best indicator of E. coli loading in the watersheds studied regardless of flow conditions and location. However, E. coli concentration and loading best correlate to 7dP and turbidity at base flow. A spatial dependency is also observed at base flow with E. coli concentration and load correlating better to 7dP in the headwaters and to turbidity in the lower reaches of the watersheds studied. For high flow conditions, E. coli concentration and loading are poorly correlated to most variables, except stream water temperature and 7-d antecedent discharge. These results are consistent with those reported in the literature and suggest that, at least during base flow conditions, turbidity and 7dP may be usable in artificially drained landscapes of the Midwest to identify potential hot spots of E. coli contamination.     

A comparison of the soil migration and plant uptake of radioactive chlorine and iodine from contaminated groundwater

A 6-month soil column experiment was conducted to compare the upward migration and plant uptake of radiochlorine and radioiodine from shallow, near-surface contaminated water tables. Both fixed and fluctuating water tables were studied. After 6 months, (36)Cl activity concentrations were relatively uniform throughout the soil profile apart from an accumulation at the soil surface, which was especially marked under a fluctuating water table scenario. In contrast, (125)I (a surrogate for (129)I) tended to accumulate at the boundary between the anoxic conditions at the base of the column and the oxic conditions above, due to its redox-dependent sorption behaviour. The uptake of (36)Cl by perennial ryegrass was much greater than that of (125)I due to its greater migration into the rooting zone and its ready availability in soil solution. In the context of radioactive waste disposal, where these radionuclides may potentially be released into groundwater, (36)Cl would be expected to present a greater potential for contamination of the biosphere than (129)I.