An Analysis of Visual Range in the Eastern United States Under Different Meteorological Regimes

ABSTRACT

The issue of fine particle (PM₂₅) exposures and their potential health effects is a focus of scientific research because of the recently promulgated National Ambient Air Quality Standard for PM_{2 5}. Before final implementation, the health and exposure basis for the standard will be reviewed by the U.S. Environmental Protection Agency within the next five years. As part of this process, it is necessary to understand total particle exposure issues and to determine the relative importance of the origin of PM_{2 5} exposure in various micro-environments. The results presented in this study examine emissions of fine particles from a previously uncharacterized indoor source: the residential vacuum cleaner. Eleven standard vacuum cleaners were tested for the emission rate of fine particles by their individual motors and for their efficiency in collecting laboratory-generated fine particles. An aerosol generator was used to introduce fine potassium chloride (KC1) particles into the vacuum cleaner inlet for the collection efficiency tests. Measurements of the motor emissions, which include carbon, and the KCl aerosol were made using a continuous HIAC/Royco 5130A light-scattering particle detector. All tests were conducted in a metal chamber specifically designed to completely contain the vacuum cleaner and operate it in a stationary position. For the tested vacuum cleaners, fine particle motor emissions ranged from 9.6 x 10⁴ to 3.34 x 10⁸ particles/min, which were estimated to be 0.028 to 176 mg/min for mass emissions, respectively. The vast majority of particles released were in the range of 0.3-0.5 mm in diameter. The lowest particle emission rate was obtained for a vacuum cleaner that had a high efficiency (HEPA) filter placed after the vacuum cleaner bag and the motor within a sealed exhaust system. This vacuum cleaner removed the KC1particles that escaped the vacuum cleaner bag and the particles emitted by the motor. Results obtained for the KC1 collection efficiency tests show >99% of the fine particles were captured by the two vacuum cleaners that used a HEPA filter. A series of tests conducted on two vacuum cleaners found that the motors also emitted ultra-fine particles above 0.01 mm in diameter at rates of greater than 10⁸ ultra-fine particles/CF of air. The model that had the best collection efficiency for fine particles also reduced the ultra-fine particle emissions by a factor of 1 x 10³.     

Effects of floaters on the free surface profiles of river flows

Environmental Fluid Mechanics - The presence of floaters should be taken into account when dealing with hydraulic analyses, e.g. when boats are moored along the river banks or large wood is...     

Mothers living with contamination of perfluoroalkyl substances: an assessment of the perceived health risk and self-reported diseases

Environmental Science and Pollution Research - Widespread contamination of the superficial, drinking, and groundwater by perfluoroalkyl substances (PFASs) was discovered in the Veneto Region...     

Biochemical parameters and bacterial species richness in soils contaminated by sludge-borne metals and remediated with inorganic soil amendments

The effectiveness of two amendments for the in situ remediation of a Cd- and Ni-contaminated soil in the Louis Fargue long-term field experiment was assessed. In April 1995, one replicate plot (S1) was amended with 5% w/w of beringite (B), a coal fly ash (treatment S1+B), and a second plot with 1% w/w zerovalent-Fe iron grit (SS) (treatment S1+SS), with the aim of increasing metal sorption and attenuating metal impacts. Long-term responses of daily respiration rates, microbial biomass, bacterial species richness and the activities of key soil enzymes (acid and alkaline phosphatase, arylsulfatase, beta-glucosidase, urease and protease activities) were studied in relation to soil metal extractability. Seven years after initial amendments, the labile fractions of Cd and Ni in both the S1+B and S1+SS soils were reduced to various extents depending on the metal and fractions considered. The soil microbial biomass and respiration rate were not affected by metal contamination and amendments in the S1+B and S1+SS soils, whereas the activity of different soil enzymes was restored. The SS treatment was more effective in reducing labile pools of Cd and Ni and led to a greater recovery of soil enzyme activities than the B treatment. Bacterial species richness in the S1 soil did not alter with either treatment. It was concluded that monitoring of the composition and activity of the soil microbial community is important in evaluating the effectiveness of soil remediation practices.     

Air pollution from a large steel factory: polycyclic aromatic hydrocarbon emissions from coke-oven batteries

A systematic investigation of solid and gaseous atmospheric emissions from some coke-oven batteries of one of Europe's largest integrated steel factory (Taranto, Italy) has been carried out. In air monitoring samples, polycyclic aromatic hydrocarbons (PAHs) were consistently detected at concentrations largely exceeding threshold limit values. By means of PAHs speciation profile and benzo(a)pyrene (BaP) equivalent dispersion modeling from diffuse sources, the study indicated that serious health risks exist not only in working areas, but also in a densely populated residential district near the factory.     

Molecular phylogeography of two Italian sibling species of Calobius (Coleoptera, Hydraenidae, Ochthebiinae) inhabiting Mediterranean marine rock-pools

Marine rock-pools, commonly found along the Mediterranean coasts, are isolated patches of habitat characterised by large spatial and temporal variations. The phylogeography of Calobius quadricollis and C. urbanelliae, two sibling species of moss beetles (Coleoptera, Hydraenidae) inhabiting Italian temporary marine rock-pool ecosystems, were studied using mitochondrial cytochrome c oxidase subunit I (COI). Our data suggest a strong association between the scored genetic variability and the geographical distribution of populations sampled for both species. These analyses provided evidences of episodic species range expansion and fragmentation, recurrent “flush and crash” and bottleneck episodes probably occurring during the Glacial Cycles. The observed phylogeographical pattern is probably related to the historical and biogeographical processes of Mediterranean areas, as well as both to the ephemeral habitat tipology and limited dispersal ability of these beetles.