Livestock housing is an important source of emissions of particulate matter (PM). High concentrations of PM can threaten the environment, as well as the health and welfare of humans and animals. Particulate matter in livestock houses is mainly coarse, primary in origin, and organic; it can adsorb and contain gases, odorous compounds, and micro-organisms, which can enhance its biological effect. Levels of PM in livestock houses are high, influenced by kind of housing and feeding, animal type, and environmental factors. Improved knowledge on particle morphology, primarily size, composition, levels, and the factors influencing these can be useful to identify and quantify sources of PM more accurately, to evaluate their effects, and to propose adequate abatement strategies in livestock houses. This paper reviews the state-of-the-art of PM in and from livestock production systems. Future research to characterize and control PM in livestock houses is discussed. Control of particulate matter emissions, a major challenge to modern livestock production.

Global demand for carbon nanotubes (CNTs) is increasing dramatically. As CNTs become commonplace, the range of uses is expected to expand as will the potential for release into ecosystems. Recent research suggests that CNTs display increased suspension in water in the presence of natural organic matter (NOM), thus increasing their ability for transport and dispersion. However, it remains unclear how CNT size will affect the suspension of CNTs in natural waters. Here we examine the effect of CNT diameter (10-500 nm) and CNT length (1-40 μm) in the presence of 1% sodium docecyl sulfate (SDS), and two different freshwater NOM extracts on suspension of CNTs in water. Absorbance spectrometry (UV-VIS) was used to determine CNT concentration in solutions over a 68 h period in the dark. Seventy to ninety-five percent of the CNTs settled out of the 1% SDS solution as compared to 23-54% in each of the NOM solutions. The half-life of suspension in solution increased with decreasing CNT diameter (from 13.9 to 138.8 h⁻¹ for solutions containing NOM). These results demonstrate that settling rates are strongly determined by NOM presence in solution as well as CNT size.

Trace elements, especially those associated with fine particles in airborne particulate matter (PM), may play an important role in PM adverse health effect. The aim of this paper is to characterize elements in a wide particle size range from nano (57-100 nm) to fine (100-1,000 nm) and to coarse (1,000-10,000 nm) fractions of two urban PM samples collected in Ottawa. Size-selective particle sampling was performed using a micro-orifice uniform deposit impactor, and element concentrations were determined in each different size fraction by inductively coupled plasma-mass spectroscopy. A general trend of increasing element concentration with decreasing aerodynamic diameter was observed for elements V, Mn, Ni, Cu, Zn, Se, and Cd, indicating they were predominately concentrated in the nanoparticle size range. Other elements including Fe, Sr, Mo, Sn, Sb, Ba, and Pb were predominately concentrated in the fine-size range. Increased concentration of elements in the nano and fine particle size range is significant due to their ability to penetrate into the deepest alveolar area of the lungs. This was confirmed by the calculation of median concentration diameters, which were less than 800 nm for most of the investigated elements. Particle size distribution and element correlation analysis suggest that the elements concentrated in the nano- and fine-size fractions originated mainly from vehicular combustion and emission. Long-range airborne transport and soil or road dust resuspension may also contribute. Particle size had an important effect on element bioaccessibility for the studied urban PM samples showing a general trend of increasing element bioaccessibility with decreasing particle size. These results emphasize the importance of acquiring information on nano and/or fine PM-bound elements and their bioaccessibilities for accurate element and PM exposure assessment.

For a half century, total suspended solids (TSS) has been the most commonly utilized particulate matter (PM) gravimetric index for wastewater. While TSS has been extended to urban runoff, runoff phenomena are unique. Runoff is unsteady and transports heterodisperse inorganic granulometry, giving rise to the PM index, suspended sediment concentration (SSC). With respect to PM-associated chemical oxygen demand (CODp) in runoff, it is hypothesized that, while the TSS method can represent effluent CODp, the SSC method is required to represent influent CODp. CODp and PM indices (TSS and SSC) for runoff events with mass balances and manual sampling are analyzed to investigate this hypothesis. This study examined a series of rainfall-runoff events captured from an instrumented fully paved urban catchment subject to traffic loadings in Baton Rouge, LA. Results indicate TSS generated substantial event-based mass balance errors for CODp and Δm p (mg/g) across a hydrodynamic separator (HS) as compared to SSC. TSS underestimates sediment-bound COD (>75 µm), a significant portion (maximum of 63% and median of 50%) of influent load. Negative bias by the TSS method for influent CODp load increases as the heterodisperse particle size distribution becomes coarser. Above a PM of 250 mg/L, underestimation of CODp by the TSS method is statistically significant. Utilizing the SSC method, CODp reduction by a HS upstream of a batch clarifier (BC) indicates that a HS does not provide CODp reduction, compared to a BC with 60 min of residence time. Representative PM and CODP assessment suggests frequent BMP and drainage system maintenance to ensure proper operation and reduce pollutant elution.

Urban drainage transports a complex and heterogeneous mixture of aqueous-phase chemicals and also solid-phase particulate matter (PM). In this study, event-scale particle size distribution (PSD) of wet and dry weather flows are measured, modeled, and compared. The flows are generated from a complex urbanizing sewershed (Liguori catchment) in Cosenza, Italy. Results indicate PSDs are heterodisperse, ranging from colloidal to sand-size PM. On an event scale, dry weather PSDs are coarser than wet weather flows, yet within each flow class results indicate flow-limited behavior and only nominal variability during and between events. PSDs from each event and flow category are modeled with a cumulative gamma distribution. Results produced nonparametric distributions of shape (γ) and scaling (α) parameters as well as a d ₅₀ index. Wet weather flows generated statistically significantly higher distributions of γ and α and statistically significantly lower d ₅₀. Nonparametric parameter distributions illustrate greater, yet still nominal variability for wet weather flows.

PURPOSE: Chlor-alkali plants are one of the most important point sources of mercury to aquatic environment. The problem of Hg contamination has been studied in a region, Rm Valcea (Romania), impacted by the wastewater discharge of a chlor-alkali plant. The purpose of the present study is to evaluate the current status of mercury pollution in the Babeni reservoir (Olt River) and the exposure of local population via fish consumption to mercury originating from the chlor-alkali plant. METHODS: Sediments were collected from Valcea, Govora and Babeni reservoirs. Grain size distribution, organic content and total mercury (THg) concentrations were analysed in sediments. Fish were purchased from local anglers, and the scalp hair was collected from volunteers. THg in sediment, fish and hair samples was determined using an atomic absorption spectrophotometer for Hg determination. Monomethylmercury (MMHg) was analysed in the muscle and liver tissues by species-specific isotope dilution and capillary gas chromatography hyphenated to inductively coupled plasma mass spectrometer. RESULTS: High mercury concentrations were found in the sediments and in fish from Babeni reservoir, with a median of 2.1 mg/kg (IQR = 3.2) in sediments and a mean value of 1.8 ± 0.8 mg/kg_ww in fish muscle. MMHg concentrations in fish were well above the WHO guidelines for fish consumption. Local population consuming fish from the Babeni reservoir had THg concentrations in hair significantly higher than those consuming fish from upstream reservoirs and/or from the shops and reached a median value of 2.5 mg/kg (IQR = 3.6). CONCLUSIONS: The remnant pollution in the fish of this reservoir, and probably many other lakes and reservoirs receiving Hg polluted wastewater, represents a considerable health risk for the local fish consumers.