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At least 1,693 records · Page 94Linked to original sources
PubMed2000

Impact of the fungicide carbendazim in freshwater microcosms. I. Water quality, breakdown of particulate organic matter and responses of macroinvertebrates.

Effects of chronic application of the fungicide Derosal(R) (active ingredient carbendazim) were studied in indoor macrophyte-dominated freshwater microcosms. The concentrations (0, 3.3, 33, 100, 330 and 1000 µg/l) were kept at a constant level for 4 weeks. This paper is the first of a series of two, and describes the fate of carbendazim and its effects on water quality parameters, breakdown of POM, and responses of macroinvertebrates. Carbendazim proved very persistent in the water layer. Values for t(12) varied between 6 and 25 weeks, and decreased with the treatment level. Significant effects on water quality parameters (DO, pH, alkalinity, conductivity) could not be demonstrated. After 4 weeks of incubation, the breakdown of Populus leaves was significantly slower at the two highest carbendazim concentrations. The macroinvertebrate community was seriously affected by carbendazim application, with Oligochaeta, Turbellaria, Hirudinea and some Crustacea as the most sensitive groups. The snail Bithynia decreased in numbers, but other gastropods increased in numbers. Safety factors as proposed by the Uniform Principles (European Union) for the risk assessment of pesticides, to be multiplied with toxicity data of the standard test species (Daphnia, fish, algae), appeared to ensure adequate protection of sensitive populations present in the microcosms.

Journal Article↗
PubMed2000

Relationship between indoor and outdoor carbonaceous particulates in roadside households.

Concentrations of particulate matter (PM) and carbonaceous particulates in indoor and outdoor air at roadside private households were measured in Osaka, Japan. The particulate samples were collected on filters using a portable AND sampler capable of separating particles into three different size ranges: over 10 microm, 2-10 microm (coarse) and below 2 microm (fine) in aerodynamic diameter. The filters were weighed and then analyzed for elemental carbon (EC) and organic carbon (OC) by thermal oxidation using a CHN CORDER. The results showed that indoor fine PM concentration is considerably affected by fine EC and the fine EC in indoor air is significantly correlated to that in outdoor air, r=0.86 (n=30, p<0.001). A simple estimation from EC content ratio in diesel exhaust particles indicated that about 30% of indoor particulates of less than 10 microm (PM10) were contributed from diesel exhaust. Additionally, the size characteristics of outdoor PM at roadside and background sites were examined using Andersen Cascade Impactors.

Journal Article↗
PubMed2004

Particulate organic matter in the sea: the composition conundrum.

As organic matter produced in the euphotic zone of the ocean sinks through the mesopelagic zone, its composition changes from one that is easily characterized by standard chromatographic techniques to one that is not. The material not identified at the molecular level is called "uncharacterized". Several processes account for this transformation of organic matter: aggregation/disaggregation of particles resulting in incorporation of older and more degraded material; recombination of organic compounds into geomacromolecules; and selective preservation of specific biomacromolecules. Furthermore, microbial activities may introduce new cell wall or other biomass material that is not easily characterized, or they may produce such material as a metabolic product. In addition, black carbon produced by combustion processes may compose a fraction of the uncharacterized organic matter, as it is not analyzed in standard biochemical techniques. Despite these poorly-defined compositional changes that hinder chemical identification, the vast majority of organic matter in sinking particles remains accessible to and is ultimately remineralized by marine microbes.

Biomass↗
PubMed2005

Determination of arsenic in air particulates and diesel exhaust particulates by spectrophotometry.

A method was developed for the determination of trace arsenic by spectrophotometry. The proposed method is rapid, simple, and inexpensive. This method can be used for sensitive determination of trace arsenic in environmental samples and especially in air particulates. The results obtained by this method as a proposed method were compared with those obtained by hydride generation atomic absorption spectrometry as a popular reported method for the determination of arsenic and an excellent agreement was found between them. The method was also used for determination of arsenic associated with airborne particulate matter and diesel exhaust particulates. The results showed that considerable amount of arsenic are associated with diesel engine particulates. The variation in concentration of arsenic was also investigated. The atmospheric concentration of arsenic was different in different sampling stations was dependent to the traffic density.

Air Pollutants↗
PubMed1994

[Cytokine production by human airway epithelial cells and its modulation].

There is increasing evidence that airway epithelial cells play an active role in allergic inflammation, including bronchial asthma. We showed that human airway epithelial cells in culture release GM-CSF, G-CSF, M-CSF, IL-6, and IL-8, using a serum-free culture system. These cytokines are known to modulate the bioactivities of inflammatory cells that accumulate at the site of inflammation. Among them, GM-CSF, IL-8, or both may be important because they influence the bioactivities of eosinophils, which are characteristic of allergic inflammation. Here we report on the effects of air pollutants such as suspended particulate matter and diesel exhaust particulates on release of cytokines from airway epithelial cells. All air pollutants we tested stimulated epithelial cells to release GM-CSF. These results suggest that one cause of the recent increase in the prevalence of allergic disorders is direct stimulation of airway epithelial cells by air-pollutants. Furthermore, anti-inflammatory agents such as steroids and anti-allergic drugs were found to suppress the release of GM-CSF from airway epithelial cells in vitro.

Air Pollutants↗
PubMedDate not supplied

Air pollution and mortality: results from a study of Santiago, Chile.

In 1986, the U.S. EPA issued an air quality standard for particulate matter that included only particulates below 10 microns in diameter (PM10). Unfortunately, epidemiological research investigating the health effects associated with PM10 has been limited by the lack of available daily data from outdoor monitoring stations. Evidence of high concentrations of PM10 in Eastern Europe and in metropolitan areas such as Mexico City and Santiago, Chile underscores the need to evaluate the association between air pollution and mortality. Over the last few years, daily measures of ambient PM10 have been collected in Santiago. Our analysis examines the relationship between PM10 and daily mortality between 1989 and 1991. In addition to total daily mortality, the data were compiled to record total mortality for all males, all females, and those over 65, and mortality from either respiratory disease or cardiovascular disease. Multiple regression analysis was used to explain mortality, with particular attention to controlling for the influence of season and temperature. The results suggest a strong association between PM10 and all of the alternative measures of mortality. The association persists after controlling for daily minimum temperature and binary variables indicating temperature extremes, the day of the week, the month, and the year. Additional sensitivity analyses suggest a fairly robust relationship. In general, a 10 micrograms/m3 change in daily PM10 was associated with a 1% increase in mortality. This relative risk is consistent with the results of recent studies undertaken in the United States.

Air Pollutants↗
PubMed2005

Chemical characterization of fine particles from on-road vehicles in the Wutong tunnel in Shenzhen, China.

Vehicle populations in China have been increasing sharply since 1990s. Vehicle emissions including various gaseous pollutants and particulate matter cause deterioration of air quality. However, measurements of particulate mater from on-road vehicles in China are scarcely reported, and thus the chemical compositions of particles emitted from vehicles in China are unknown. In this research, tunnel experiments were performed to measure PM2.5 in the Wutong tunnel, Shenzhen, China. Detailed PM2.5 chemical compositions, with organic compounds determined by GC/MS, in the tunnel were presented. Elemental carbon and organic matter composed 63% and 34% of the total PM2.5 mass in the Wutong tunnel, respectively. Alkanes, PAHs, hopanes, fatty acids, and dicarboxylic acids were the major identified organic compounds, and their source profiles in the PM2.5 in the Wutong tunnel were characterized. The comparisons of our measurements with those in the literature were also made to demonstrate the characteristics of the vehicle source profiles in the Wutong tunnel. The experimental results in this paper can improve understanding of particulate matter emitted from vehicles in China.

Air Pollutants↗
PubMed2001

Chemical speciation of plutonium in seawater.

Concentrations of particulate and dissolved plutonium in seawater were determined together with strong organic ligands (SOL) in particulate matter (PM). The concentration of particulate 239,240Pu in surface waters of the Western North Pacific ranged from 0.03 to 0.3 mBq m(-3) during the period from 1987 to 1997. The percentage of particulate Pu to total Pu in seawater was less than 10% in surface waters, whereas its portions were less than 1% in deep waters. In order to characterize particulate Pu in seawater, the relationships between particulate Pu, dissolved Pu and SOL concentrations in surface PM were examined. The result reveals that particulate Pu was linearly related to the SOL concentration independent of dissolved Pu concentration. Mass balance analysis suggests that a dominant chemical form of Pu in surface PM, which may exist as Pu(IV), is a complex with strong organic ligands in PM.

Pacific Ocean↗
PubMed2006

Measurements of inhalable particles<10 microm (PM(10)) and total suspended particulates (TSP) concentrations along the north-south corridor, in Kolkata, India.

The 24-hour concentrations of total suspended particulate matter (TSP) and respirable suspended particulates (PM(10)) were monitored during March 2003 to February 2004 from a network of 15 sampling stations along a populated urban corridor of Kolkata City in India. The air samplers were placed at a distance 20-200 m from roadways and their height from ground level was within 3 to 5 m. It was also insured that from any obstacle to the airflow was at least 30 cm away. Over the study area, the monthly average concentrations of TSP and PM(10) were found to be 200.3 +/-93.1 microg/m(3) and 95.8+/-67.5 microg/m(3), respectively, while the 24-hour average concentrations were in the range of 17--456 microg/m(3) and 15--291 microg/m(3), respectively. The higher average values at particular stations reflected the closeness of those to heavy road traffic. With regards to the temporal variations, higher concentrations were observed during winter and lower concentrations during monsoon. Statistical analysis of the sampling data was conducted to obtain general characteristics of the particulate pollution and to investigate the effects of traffic volume and meteorological factors on the pollution level. TSP and PM(10) concentrations were found to be highly correlated with each other at all the sampling stations. There were clear associations between TSP and PM(10) data set at all the measured 15 stations and on average, PM(10) was 52% of the total TSP concentration.

Air Pollutants↗
PubMed1980

Worker exposure to chemical agents in the manufacture of rubber tires and tubes: particulates.

The Occupational Health Studies Group industrial hygiene studies at a group of 14 tire and tube manufacturing plants chosen to represent a cross-section of the industry include numerous evaluations of potential exposure to airborne particulate matter. Results of these environmental particulate sampling studies are reported by plant and by occupational groups within plants. High volume, open face and cyclone samplers were employed to evaluate both personnel and area particulate concentrations. The concentrations of particulates yielded by high volume and open face total particulate samplers are compared with those of comparison samples of respirable material. Personnel samples of particulates are compared with general air samples taken in the same work areas. An overall review and comparison is given of particulate exposures to workers in various occupational title groups where particulate materials are released to the air from processes or operations.

Air↗
PubMed1999

Healthy women's PEF variations with ambient summer concentrations of PM10, PM2.5, SO42-, H+, and O3.

The relationship between ambient air pollution and daily change in peak expiratory flow (PEF) was studied in a sample of 473 nonsmoking women (age 19 to 43 yr) in Virginia over summers 1995- 1996. Daily 24-h averages of particulate matter (PM2.5 and PM10), fine particulate sulfate (SO42-) and strong acid (H+), hourly ozone (O3), and select meteorologic variables (e.g., temperature) were collected at a regional outdoor monitoring site. Subjects took PEF measurements twice daily for a 2-wk period using a standard MiniWright peak flow meter. Concurrent measures for summer periods of 24-h PM2.5 (micrograms/m3) ranged from 3.5 to 59.7; H+ (nmol/m3) from 0 to 250; maximal daily 8-h average O3 (ppb) from 17.0 to 87.6. Morning PEF decrements were significantly associated with H+ and PM2. 5. An increase of 50 etamol/m3 of H+ and 10 micrograms/m3 of PM2.5 related to decreases of 0.89 (95% CI = 0.21 to 1.57) and 0.73 (95% CI = 0.07 to 1.38) L/min in morning PEF, respectively. Ozone was the only exposure related to evening PEF with 5-d cumulative lag exposure showing the greatest effect; 7.65 L/ min (95% CI = 2.25 to 13.0) decrease per 30 ppb O3 increase. Separate physiologic effects were observed for summer ambient concentrations of two different pollutants (PEF decrements related to PM2.5 in morning and O3 in evening) at concentrations below the new U.S. EPA 24-h ambient air quality standard for PM2.5 and 8-h standard for O3.

Adult↗
PubMed2026

Metagenomic insights into biogeochemical functional potential and resistome dynamics of PM2.5 microbial communities.

Atmospheric particulate matter harbors diverse microorganisms, yet their functional potential in biogeochemical cycling and the associated risks of resistome remain poorly understood. Here, we performed metagenomic sequencing on PM2.5 samples collected across four months to unravel the microbial genetic repertoire involved in methane, nitrogen, phosphorus, and sulfur cycling, as well as the resistome, and pathogen composition. A broad range of functional genes was detected for each biogeochemical cycle, with more than 65% of gene subtypes shared across all months, indicating conserved functional signatures. In contrast, more than 80% of the resistome showed temporal variation in abundance, with the lowest richness observed in March. Temporal shifts were also observed in resistome composition, with several resistance determinants reaching higher abundances in April and May. Network analysis indicated frequent co-occurrence among several pathogenic and opportunistic taxa. Contig-based profiling identified 51 potential pathogenic taxa, including 32 human- or animal-associated taxa. In addition, both PM10 and PM2.5 concentrations were associated with pathogen abundance and functional gene richness (e.g., antibiotic resistance genes and virulence factors). Together, this metagenomic survey suggests contrasting temporal patterns between conserved biogeochemical functional potential and more variable resistome-related traits in PM2.5 microbial communities. While constrained by limited temporal coverage and sample size, this study provides preliminary insights into the ecological and potential public health relevance of airborne microbial communities in urban environments.

Particulate Matter↗