Dispersion modeling to compare alternative technologies for odor remediation at swine facilities

The effectiveness of 18 alternative technologies for reducing odor dispersion at and beyond the boundary of swine facilities was assessed in conjunction with an initiative sponsored through agreements between the Attorney General of North Carolina and Smithfield Foods, Premium Standard Farms, and Frontline Farmers. The trajectory and spatial distribution of odor emitted at each facility were modeled at 200 and 400 m downwind from each site under two meteorological conditions (daytime and nighttime) using a Eulerian-Lagrangian model. To predict the dispersion of odor downwind, the geographical area containing the odorant sources at each facility was partitioned into 10-m2 grids on the basis of satellite photographs and architectural drawings. Relative odorant concentrations were assigned to each grid point on the basis of intensity measurements made by the trained odor panel at each facility using a 9-point rating scale. The results of the modeling indicated that odor did not extend significantly beyond 400 m downwind of any of the test sites during the daytime when the layer of air above the earth's surface is usually turbulent. However, modeling indicated that odor from all full-scale farms extended beyond 400 m onto neighboring property in the evenings when deep surface cooling through long-wave radiation to space produces a stable (nocturnal) boundary layer. The results also indicated that swine housing, independent of waste management type, plays a significant role in odor downwind, as do odor sources of moderate to moderately high intensity that emanate from a large surface area such as a lagoon. Human odor assessments were utilized for modeling rather than instrument measurements of volatile organic compounds (VOCs), hydrogen sulfide, ammonia, or particulates less than 10 microm in diameter (PM10) because these physical measurements obtained simultaneously with human panel ratings were not found to accurately predict human odor intensity in the field.     

Mineralogical Investigation of an Enterolith from a Grant's Zebra

An enterolith surgically removed from a Grant's zebra was investigated by standard mineralogical techniques including X-ray diffraction, scanning electron microscopy and electron microprobe analysis. It was predominantly composed of a suite of phosphate minerals which have precipitated on and between aggregates of undigested plant material. It was apparently cored by a small nidus of granitic rock which served as a site for heterogeneous nucleation for the larger phosphatic overgrowth. Phosphate was deposited by at least two distinct mechanisms. In the enterolith's core, phosphate minerals replaced or rimmed silicate grains (e.g. feldspars and quartz) which are relics of the disaggregated granitic nidus. As the enterolith subsequently accreted outwards from the nidus, struvite was precipitated directly onto fibres of plant material, or within the pore spaces between them. The generally fine grain size of struvite in enteroliths, relative to that in urinary calculi, may be due to the ubiquitous presence of the undigested plant fibres. Struvite, close to (NH₃)_0.9K_0.1MgPO₄ · 6H₂O in composition, is the only phosphate mineral in the outer portions of the enterolith. Within the enterolith's interior, struvite occurs subequally with Mg-vivianite, close to Mg_2.9Fe_0.1(PO₄)₂ · 8H₂O in composition. Textural relations suggest that the mineralogical transformation of struvite to Mg-vivianite is a consequence of diagenesis, presumably related to a decrease in pH and/or (NH₄)⁺ activity, within the core of the enterolith. If enterolith growth is mediated by the accumulation of a particular form of undigested plant fibre (e.g. lucerne hay), the identification and dietary removal of this material may prevent or at least impede the development of enteroliths.     

The environmental impact statement comes to Israel: An initial assessment

Despite obstacles inherent in the structure of government and the lack of a strong national constituency, environmental impact assessment became a policy-making element in the government of Israel in 1982. The Environmental Protection Service formed in 1973 now needs to develop strategies to promote environmental awareness and environmentally informed decision making among the public, private and public developers, and within the Ministry of the Interior.     

Science of odor as a potential health issue

Historically, unpleasant odors have been considered warning signs or indicators of potential risks to human health but not necessarily direct triggers of health effects. However, citizen complaints to public health agencies suggest that odors may not simply serve as a warning of potential risks but that odor sensations themselves may cause health symptoms. Mal-odors emitted from large animal production facilities and wastewater treatment plants, for example, elicit complaints of eye, nose, and throat irritation, headache, nausea, diarrhea, hoarseness, sore throat, cough, chest tightness, nasal congestion, palpitations, shortness of breath, stress, drowsiness, and alterations in mood. There are at least three mechanisms by which ambient odors may produce health symptoms. First, symptoms can be induced by exposure to odorants (compounds with odor properties) at levels that also cause irritation or other toxicological effects. That is, irritation--rather than the odor--is the cause of the health symptoms, and odor (the sensation) simply serves as an exposure marker. Second, health symptoms from odorants at non-irritant concentrations can be due to innate (genetically coded) or learned aversions. Third, symptoms may be due to a co-pollutant (such as endotoxin) that is part of an odorant mixture. Objective biomarkers of health symptoms must be obtained, however, to determine if health complaints constitute health effects. One industry that is receiving much attention, worldwide, related to this subject is concentrated animal production agriculture. Sustainability of this industry will likely necessitate the development of new technologies to mitigate odorous aerial emissions. Examples of such "environmentally superior technologies" (EST) developed under the initiative sponsored through agreements between the Attorney General of North Carolina and Smithfield Foods and Premium Standard Farms are described.