Naphthalene emissions from moth repellents or toilet deodorant blocks determined using head-space and small-chamber tests

The present study investigated the emissions of naphthalene and other compounds from several different moth repellents(MRs) and one toilet deodorant block(TDB)currently sold in Korea,using a headspace analysis.The emission factors and emission rates of naphthalene were studied using a small-scale environmental chamber.Paper-type products emitted a higher concentration of the total volatile organic compounds(VOCs)(normalized to the weight of test piece)than ball-type products,which in turn emitted higher ...     

Temporal analysis of airborne particulate matter reveals a dose-rate effect on mortality in El Paso: indications of differential toxicity for different particle mixtures

One of two topics explored is the limitations of the daily average in summarizing pollutant hourly profiles. The daily average of hourly measurements of air pollutant constituents provides continuity with previous studies using monitoring technology that only provided the daily average. However, other summary statistics are needed that make better use of all available information in 24-hr profiles. The daily average reflects the total daily dose, obscuring hourly resolution of the dose rate. Air pollutant exposures with comparable total daily doses may have very different effects when occurring at high levels over a few hours as opposed to low levels over a longer time. Alternative data-based choices for summary statistics are provided using principal component analysis to capture the exposure dose rate, while preserving ease of interpretation. This is demonstrated using the earliest hourly particle concentration data available for El Paso from archived records of particulate matter (PM)10. In this way, a significant association between evening PM10 exposures and nonaccidental daily mortality is found in El Paso from 1992 to 1995, otherwise missed using the daily average. Secondly, the nature and, hence, effects of particles in the ambient aerosol during El Paso sandstorms is believed different from that of particles present during still-air conditions resulting from atmospheric temperature inversions. To investigate this, wind speed (ws) is used as a surrogate variable to label PM10 exposures as Low-ws (primarily fine particles), High-ws (primarily coarse particles), or Mid-ws (a mixture of fine and coarse particles). A High-ws evening is significantly associated with a 10% lower risk of mortality on the succeeding third day, as compared with comparable exposures at Low- or Mid-ws. Although this analysis cannot be used to form firm conclusions because it uses a very small data set, it demonstrates the limitations of the daily average and suggests differential toxicity for different particle compositions.     

Environmental behavior of explosives in groundwater from the Milan Army Ammunition Plant in aquatic and wetland plant treatments. Removal, mass balances and fate in groundwater of TNT and RDX.

Phytoremediation of 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in groundwater using constructed wetlands is a potentially economical remediation alternative. To evaluate Explosives removal and fate was evaluated using hydroponic batch incubations of plant and substrate treatments with explosives-contaminated groundwater amended with [U-14C]-TNT or [U-14C]-RDX. Plants and substrates were collected from a small-scale wetland constructed for explosives removal, and groundwater originated from a local aquifer at the Milan Army Ammunition Plant. The study surveyed three aquatic, four wetland plant species and two substrates in independent incubations of 7 days with TNT and 13 days with RDX. Parent compounds and transformation products were followed using 14C and chemical (HPLC) analyses. Mass balance of water, plants, substrates and air was determined. It was demonstrated that TNT disappeared completely from groundwater incubated with plants, although growth of most plants except parrot-feather was low in groundwater amended to contain 1.6 to 3.4 mg TNT L-1. Highest specific removal rates were found in submersed plants in water star-grass and in all emergent plants except wool-grass. TNT declined less with substrates, and least in controls without plants. Radiolabel was present in all plants after incubation. Mineralization to 14CO2 was very low, and evolution into 14C-volatile organics negligible. RDX disappeared less rapidly than TNT from groundwater. Growth of submersed plants was normal, but that of emergent plants reduced in groundwater amended to contain 1.5 mg RDX L-1. Highest specific RDX removal rates were found in submersed plants in elodea, and in emergent plants in reed canary grass. RDX failed to disappear with substrates. Mineralization to 14CO2 was low, but relatively higher than in the TNT experiment. Evolution into 14C-volatile organics was negligible. Important considerations for using certain aquatic and wetland plants in constructed wetlands aimed at removing explosives from water are: (1) plant persistence at the explosives level to which it is exposed, (2) specific plant-mass based explosives removal rates, (3) plant productivity, and (4) fate of parent compounds and transformation products in water, plants, and sediments.     

Effect of Nile River water quality on algal distribution at Cairo,Egypt

Changes of phytoplankton density and their relation to physicochemical characteristics along the Nile River have been noted in the Cairo district between 1976 and 1982. Three major phytoplankton groups were found to dominate the river Nile: green algae, blue-green algae, and diatoms. Diatoms represent the most dominant group and comprised from 42% to 96% of the phytoplankton community during the investigated period. Blue-green algae comprised from 0.7% to 48% of total cell number. Green algae represent the low percentage group, which ranges from 0.2% to 41% of Nile water algae. High species diversity (H′) was detected in green algae (1.22) followed by diatoms (0.84); the lowest diversity was in blue-green algae (0.45). The density of total phytoplankton count fluctuated between 10⁶ and 10⁷ organism/L. The concentration of chlorophyll-a ranged from 5 to 37 mg/m³. Primary production rates in the Nile River ranged from 8.5 to 52 mg O₂/m³h. Statistical analysis revealed significant positive correlations between chlorophyll-a content, and concentrations of phosphoruss and nitrate. Phytoplankton diversity, primary production, ammonia, and nitrite content revealed that there is no indication of pollution in the Nile.     

Creating and validating GIS measures of urban design for health research

Studies relating urban design to health have been impeded by the unfeasibility of conducting field observations across large areas and the lack of validated objective measures of urban design. This study describes measures for five dimensions of urban design - imageability, enclosure, human scale, transparency, and complexity - created using public geographic information systems (GIS) data from the US Census and city and state government. GIS measures were validated for a sample of 588 New York City block faces using a well-documented field observation protocol. Correlations between GIS and observed measures ranged from 0.28 to 0.89. Results show valid urban design measures can be constructed from digital sources.     

Thermal Stability and Degradation of Chitosan Modified by Acetophenone

N-(Methylphenylmethylidenyl) chitosan (MPMC) polymer was synthesized by chemical modification of chitosan. The chemical structure of the modified polymer was characterized by IR, ¹H NMR and elemental analysis. Thermogravimetric reveals that the thermal stability of chitosan polymer is greater than MPMC polymer. The activation energies of thermal degradation of chitosan and MPMC polymers determined using Arrhenius relationship. Thermal degradation of MPMC polymer was studied and the products of degradation were identified by GC–MS technique. It seems that the mechanism of degradation of MPMC polymer is characterized by elimination of low-molecular weight radicals. Combination or recombination of H^· or OH⁻ with these radicals and random scission mechanism along the backbone chain are the main source of the degradation products.