Measured summertime concentrations of particulate components,Hg0, and speciated polycyclic aromatic hydrocarbons at rural sites in New York State

Daily PM2.5 samples, Hg0 and speciated polycyclic aromatic hydrocarbon (PAH) were simultaneously collected at Potsdam and Stockton site in NY during the summers of 2000 and 2001. Samples for determination of the mass concentration and chemical composition of the PM2.5 were obtained with a speciation network PM2.5 sampler. Chemical composition including trace elemental composition, water-soluble ions, and elemental carbon were analyzed. Elemental mercury and PAHs were sampled separately. Daily PM2.5 concentrations ranged from 0.47 to 53.7 microg m(-3) at the Potsdam site, and from 0.82 to 47.23 microg m(-3) at the Stockton site with large daily differences between the two sites. Potsdam consistently had lower mass values than Stockton. The greatest contributors to the PM2.5 mass (generally >0.1 microg/m(3)) were sulfate, nitrate, ammonium, and BC at both sites. Seventeen PAHs were identified at each site in 2000 and the average total concentrations were 3.2 ng/m(3) and 2.9 ng/m(3) at the Potsdam and Stockton sites, respectively. The mean vapor phase mercury concentration at the Potsdam site (2.4 +/-1.2 ng m(-3), n=93) was higher than that at the Stockton site (1.2 +/- 1.0 ng m(-3), n=60) in 2000, whereas in 2001, the average concentrations were 1.1 ng m(-3) and 1.6 ng m(-3) at the Potsdam and Stockton sites, respectively. In general, vapor phase mercury concentrations increased with increasing ambient temperature at the Stockton site in 2000. These differences in values between 2000 and 2001 can be largely explained by distinct differences in the meteorological regimes that dominated in the different years.     

Nitrifying community analysis in a single submerged attached-growth bioreactor for treatment of high-ammonia waste stream.

This study investigated the nitrifying community structure in a single-stage submerged attached-growth bioreactor (SAGB) that successfully achieved stable nitrogen removal over nitrite of a high-strength ammonia wastewater. The reactor was operated with intermittent aeration and external carbon addition (methanol). With influent ammonia and total Kjeldahl nitrogen ranging from 537 to 968 mg/L and 643 to 1510 mg/L, respectively, 85% nitrogen removal was obtained, and effluent was dominated by nitrite (NO2-/NOx > 0.95). Nitrifying community analysis using fluorescence in situ hybridization (FISH), with a hierarchical set of probes targeting known ammonia-oxidizing bacteria (AOB) within beta-proteobacteria, showed that the AOB community of the biofilter consists almost entirely of members of the Nitrosomonas europaea/eutropha and the Nitrosococcus mobilis lineages. Image analysis of FISH pictures was used to quantify the identified AOB, and it was estimated that Nitrosomonas europaea/eutropha-like AOB accounted for 4.3% of the total volume of the biofilm, while Nitrosococcus mobilis-like AOB made up 1.2%; these numbers summed up to a total AOB fraction of 5.5% of the total volume on the biofilm. Nitrite-oxidizing bacteria (NOB) were not detectable in the biofilm samples with probes for either Nitrospira sp. or Nitrobacter sp., which indicated that NOB were either absent from the biofilters or present in numbers below the detection limit of FISH (< 0.1% of the total biofilm). Nitrite oxidizers were likely outcompeted from the system because of the free ammonia inhibition and the possibility that the aeration period (from intermittent aeration) was not sufficiently long for the NOB to be released from the competition for oxygen with heterotrophs and AOB. The nitrogen removal via nitrite in a SAGB reactor described in this study is applicable for high-ammonia-strength wastewater treatment, such as centrate or industrial wastes.     

The relationship between real-time and time-integrated coarse (2.5-10 micrm), intermodal (1-2.5 microm), and fine (<2.5 microm) particulate matter in the Los Angeles basin

A periodic review of the National Ambient Air Quality Standards for Particulate Matter by the U.S. Environmental Protection Agency (EPA) will assess the standards with respect to levels, particle size, and averaging times. Some members of the scientific community in the United States and Europe have suggested the use of PM1 instead of PM2.5 as the fine particle measurement standard. This proposed standard is intended to reduce the influence of coarse particle sources on PM2.5, because some evidence suggests that PM1-2.5 is dominated by coarse particulate matter (PM) sources. In this study, coarse (PM2.5-10), intermodal (PM1-2.5), and fine (PM2.5) mass concentrations at four different sites are measured with continuous and time-integrated sampling devices. The main objective is to compare variations in these three size ranges while considering the effects of location, sources, weather, wind speed, and wind direction. Results show strong correlations between PM1 and intermodal PM in receptor sites. The contribution of PM1-2.5 to PM2.5 is highest in the summer months, most likely due to enhanced long-range transport. Coarse PM is poorly correlated with intermodal PM. Continuous data suggest that PM1 is growing into PM1-2.5 via complex processes involving stagnation of the aerosol during high relative humidity conditions, followed by advection during daytime hours.     

Mobilization of colloids in groundwater due to infiltration of water at a coal ash disposal site

We investigated groundwaters in the vicinity of a coal ash site near an electric generating station in the western U.S.A. The purpose of the study was to ascertain why fine particles or colloids appear in some subsurface water samples there. If such fine particles are merely introduced during bailing or pumping operations which suspend otherwise immobile soil colloids, we should exclude these particulate materials from the water samples before analysis intended to quantify what is moving through the aquifer. However, if the colloids were truly suspended and moving with the groundwater flow in situ, then we should includes their contribution to our assessment of the mobile loads.Application of very careful sampling techniques (slow pumping rates, no atmospheric exposure) did not cause the large quantities of colloids observed previously to disappear from well water in which they occured. Additionally, the same sampling procedures did not cause similar abundances of colloids to appear in waters collected from neighboring wells installed and developed in the same manner and in the same geologic strata. Thus we believe sampling artifacts do not explain the colloids' presence in the groundwater samples.On the other hand, the groundwater chemistry and the nature of the suspended colloids (size, composition) strongly suggest these fine particles were suspended and therefore moving with the groundwater flow. At wells exhibiting large amounts of suspended colloids (≈10–100 mg L⁻¹), the water was enriched in CO₂ and depleted in O₂ relative to nearby locations. The colloids were typically between 0.1 and 2 μm in size and were primarily silicates. These results suggest to us that, where infiltrating water is percolating through a site that has been mixed with coal ash, the secondary carbonate mineral in the soils are being dissolved; removal of this cementing carbonate phase may consequently release soil silicate colloids to be carried in the flowing water.Such processes may enhance contaminant transport in groundwater by augmenting the pollutant load moving in the groundwater, and increasing the permeability of the porous medium to pollutant infiltration with water water and/or rainwater.     

The ecotoxicology of vegetable versus mineral based lubricating oils: 3. Coral fertilization and adult corals

Biodegradable vegetable-derived lubricants (VDL) might be less toxic to marine organisms than mineral-derived oils (MDL) due to the absence of high molecular weight aromatics, but this remains largely untested. In this laboratory study, adult corals and coral gametes were exposed to various concentrations of a two-stroke VDL-1A and a corresponding MDL to determine which lubricant type was more toxic to each life stage. In the fertilization experiment, gametes from the scleractinian coral Acropora microphthalma were exposed to water-accommodated fractions (WAF) of VDL-1A and MDL for four hours. The MDL and VDL-1A WAFs inhibited normal fertilization of the corals at 200 microg l(-1) total hydrocarbon content (THC) and 150 microg l(-1) THC respectively. Disturbance of a stable coral-dinoflagellate symbiosis is regarded as a valid measure of sub-lethal stress in adult corals. The state of the symbiosis in branchlets of adult colonies of Acropora formosa was monitored using indicators such as dinoflagellate expulsion and dark-adapted photosystem II yields of dinoflagellate (using pulse amplitude modulation fluorescence). An effect on symbiosis was measurable following 48 h exposure to the lubricants at concentrations of 190 microg l(-1) and 37 microg l(-1) THC for the MDL and VDL-1A respectively. GC/MS revealed that the main constituent of the VDL-1A WAF was the compound coumarin, added by the manufacturer to improve odour. The fragrance containing coumarin was removed from the lubricant formulation and the toxicity towards adult corals re-examined. The coumarin-free VDL-2 exhibited significantly less toxicity towards the adult corals than all of the other oil types tested, with the only measurable effect being a slight but significant drop in photosynthetic efficiency at 280 microg l(-1).     

Thermal degradation of fluorotelomer treated articles and related materials

This study reports the first known studies to investigate the thermal degradation of a polyester/cellulose fabric substrate ("article") treated with a fluorotelomer-based acrylic polymer under laboratory conditions conservatively representing typical combustion conditions of time, temperature, and excess air level in a municipal incinerator, with an average temperature of 1000 degrees C or greater over approximately 2s residence time. The results demonstrate that the polyester/cellulose fabric treated with a fluorotelomer-based acrylic polymer is destroyed and no detectable amount of perfluorooctanoic acid (PFOA) is formed under typical municipal incineration conditions. Therefore, textiles and paper treated with such a fluorotelomer-based acrylic polymer disposed of in municipal waste and incinerated are expected to be destroyed and not be a significant source of PFOA in the environment.     

Investigation of sources of atmospheric aerosol at a hot spot area in Dhaka, Bangladesh

Samples of fine and coarse fractions of airborne particulate matter were collected at the Farm Gate area in Dhaka from July 2001 to March 2002. Dhaka is a hot spot area with very high pollutant concentrations because of the proximity of major roadways. The samples were collected using a "Gent" stacked filter unit in two fractions of 0- to 2.2-microm and 2.2- to 10-microm sizes. The samples were analyzed for elemental concentrations by particle-induced X-ray excitation (PIXE) and for black carbon by reflectivity methods, respectively. The data were analyzed by positive matrix factorization (PMF) to identify the possible sources of atmospheric aerosols in this area. Six sources were found for both the coarse and fine PM fractions. The data sets were also analyzed by an expanded model to explore additional sources. Seven and six factors were obtained for coarse and fine PM fractions, respectively, in these analyses. The identified sources are motor vehicle, soil dust, emissions from construction activities, sea salt, biomass burning/brick kiln, resuspended/fugitive Pb, and two-stroke engines. From the expanded modeling, approximately 50% of the total PM2.2 mass can be attributed to motor vehicles, including two-stroke engine vehicle in this hot spot in Dhaka, whereas the PMF modeling indicates that 45% of the total PM2.2 mass is from motor vehicles. The PMF2 and expanded models could resolve approximately 4% and 3% of the total PM2.2 mass as resuspended/fugitive Pb, respectively. Although, Pb has been eliminated from gasoline in Bangladesh since July 1999, there still may be substantial amounts of accumulated lead in the dust near roadways as well as fugitive Pb emissions from battery reclaimation and other industries. Soil dust is the largest component of the coarse particle fraction (PM2.2-10) accounting for approximately 71% of the total PM2.2-10 mass in the expanded model, whereas from the PMF modeling, the dust (undifferentiated) contribution is approximately 49%.     

Waterborne and sediment toxicity of fluoxetine to select organisms

Ecological risk assessments of pharmaceuticals are currently difficult because little-to-no aquatic hazard and exposure information exists in the peer-reviewed literature for most therapeutics. Recently several studies have identified fluoxetine, a widely prescribed antidepressant, in municipal effluents. To evaluate the potential aquatic toxicity of fluoxetine, single species laboratory toxicity tests were performed to assess hazard to aquatic biota. Average LC(50) values for Ceriodaphnia dubia, Daphnia magna, and Pimephales promelas were 0.756 (234 microg/l), 2.65 (820 microg/l), and 2.28 microM (705 microg/l), respectively. Pseudokirchneriella subcapitata growth and C. dubia fecundity were decreased by 0.044 (14 microg/l) and 0.72 microM (223 microg/l) fluoxetine treatments, respectively. Oryias latipes survival was not affected by fluoxteine exposure up to a concentration of 28.9 microM (8.9 mg/l). An LC(50) of 15.2 mg/kg was estimated for Chironomus tentans. Hyalella azteca survival was not affected up to 43 mg/kg fluoxetine sediment exposure. Growth lowest observed effect concentrations for C. tentans and H. azteca were 1.3 and 5.6 mg/kg, respectively. Our findings indicate that lowest measured fluoxetine effect levels are an order of magnitude higher than highest reported municipal effluent concentrations.     

Water chemistry influences on long-term dissolution kinetics of CdSe/ZnS quantum dots

Widespread usage of engineered metallic quantum dots(QDs) within consumer products has evoked a need to assess their fate within environmental systems.QDs are mixed-metal nanocrystals that often include Cd~(2+)which poses a health risk as a nanocrystal or when leached into water.The goal of this work is to study the long-term metal cation leaching behavior and the factors affecting the dissolution processes of mercaptopropionic acid(MPA) capped CdSe/ZnS QDs in aphotic conditions.QD suspensions were prepared in different water conditions,and release of Zn2+and Cd~(2+) cations were monitored over time by size exclusion chromatography-inductively coupled plasm a-mass spectrometry.In most conditions with dissolved 02 present,the ZnS shell degraded fairly rapidly over～1 week,while some of the CdSe core remained up to 80 days.Additional MPA,Zn~(2+),and Cd2+temporarily delayed dissolution,indicating a moderate role for capping agent detachment and mineral solubility.The presence of H_2 O_2 and the ligand ethylenediaminetetraacetate accelerated dissolution,while NOM had no kinetic effect.No dissolution of CdSe core was observed when 02 was absent or when QDs formed aggregates at higher concentrations with 02 present.The shrinking particle model with product layer diffusion control best describes Zn2+and Cd~(2+) dissolution kinetics.The longevity of QDs in their nanocrystal form appears to be partly controlled by environmental conditions,with anoxic,aphotic environments preserving the core mineral phase,and oxidants or complexing ligands promoting shell and core mineral dissolution.