A two-stage cyclone using microcentrifuge tubes for personal bioaerosol sampling

Personal aerosol samplers are widely used to monitor human exposure to airborne materials. For bioaerosols, interest is growing in analyzing samples using molecular and immunological techniques. This paper presents a personal sampler that uses a two-stage cyclone to collect bioaerosols into disposable 1.5 ml Eppendorf-type microcentrifuge tubes. Samples can be processed in the tubes for polymerase chain reaction (PCR) or immunoassays, and the use of multiple stages fractionates aerosol particles by aerodynamic diameter. The sampler was tested using fluorescent microspheres and aerosolized fungal spores. The sampler had first and second stage cut-off diameters of 2.6 microm and 1.6 microm at 2 l min(-1)(geometric standard deviation, GSD = 1.45 and 1.75), and 1.8 microm and 1 microm at 3.5 l min(-1)(GSD = 1.42 and 1.55). The sampler aspiration efficiency was >or=98% at both flow rates for particles with aerodynamic diameters of 3.1 microm or less. For 6.2 microm particles, the aspiration efficiency was 89% at 2 l min(-1) and 96% at 3.5 l min(-1). At 3.5 l min(-1), the sampler collected 92% of aerosolized Aspergillus versicolor and Penicillium chrysogenum spores inside the two microcentrifuge tubes, with less than 0.4% of the spores collecting on the back-up filter. The design and techniques given here are suitable for personal bioaerosol sampling, and could also be adapted to design larger aerosol samplers for longer-term atmospheric and indoor air quality sampling.     

Community-Based Integrated Watershed Management

1 INTRODUCTIONIn the past, natural resources management initiatives havefocused on large but specific sector projects such as dams,reservoirs for water supply schemes, irrigation systems,crop production, at forestation, etc. Often these projectswere treated as technical and administrative issues ratherthan as a socio-economic and political one. However, thehigh social and environmental cost of such schemes haveled to a change of paradigm since the 1980s towards small-scale community projec…     

Fungicidal values of bio-oils and their lignin-rich fractions obtained from wood/bark fast pyrolysis

Pine wood, pine bark, oak wood and oak bark were pyrolyzed in an auger reactor. A total of 16 bio-oils or pyrolytic oils were generated at different temperatures and residence times. Two additional pine bio-oils were produced at the National Renewable Energy Laboratory in a fluidized-bed reactor at different temperatures. All these bio-oils were fractionated to obtain lignin-rich fractions which consist mainly of phenols and neutrals. The pyrolytic lignin-rich fractions were obtained by liquid-liquid extraction. Whole bio-oils and their lignin-rich fractions were studied as potential environmentally benign wood preservatives to replace metal-based CCA and copper systems that have raised environmental concerns. Each bio-oil and several lignin-rich fractions were tested for antifungal properties. Soil block tests were conducted using one brown-rot fungus (Gloeophyllum trabeum) and one white-rot fungus (Trametes versicolor). The lignin-rich fractions showed greater fungal inhibition than whole bio-oils for a impregnation solution 10% concentration level. Water repellence tests were also performed to study wood wafer swelling behavior before and after bio-oil and lignin-rich fraction treatments. In this case, bio-oil fractions did not exhibit higher water repellency than whole bio-oils. Comparison of raw bio-oils in soil block tests, with unleached wafers, at 10% and 25% bio-oil impregnation solution concentration levels showed excellent wood preservation properties at the 25% level. The good performance of raw bio-oils at higher loading levels suggests that fractionation to generate lignin-rich fractions is unnecessary. At this more effective 25% loading level in general, the raw bio-oils performed similarly. Prevention of leaching is critically important for both raw bio-oils and their fractions to provide decay resistance. Initial tests of a polymerization chemical to prevent leaching showed some success.     

Field scale characterization and modeling of contaminant release from a coal tar source zone

A coal tar contaminated site was characterized using traditional and innovative investigation methods. A careful interpretation of hydrogeological and hydrogeochemical data allowed for the conceptualization of the heterogeneous coal tar distribution in the subsurface. Past and future contaminant release from the source zone was calculated using a modeling framework consisting of a three-dimensional steady-state groundwater flow model (MODFLOW) and two hydrogeochemical models (MIN3P). Computational time of long-term simulations was reduced by simplifying the coal tar composition using 3 composite and 2 individual constituents and sequential application of a 2D centerline model (for calibration and predictions) and a 3D model (only for predictions). Predictions were carried out for a period of 1000 years. The results reveal that contaminant mass flux is governed by the geometry of zones containing residual coal tar, amount of coal tar, its composition and the physicochemical properties of the constituents. The long-term predictions made using the 2D model show that even after 1000 years, source depletion will be small with respect to phenanthrene, 89% of initial mass will be still available, and for the moderately and sparingly soluble composite constituents, 60% and 98%, respectively.     

Changes in plasma thyroid hormones and cortisol levels in crucian carp (Carassius auratus) exposed to the extracted microcystins

The endocrine response of crucian carp injected intraperitoneally with extracted microcystins (MC) was investigated in this study. Fish were injected intraperitoneally either with 0.75% NaCl (control) and Microcystis extract corresponding to 150 and 600 microg microcystins per kg body weight. The plasma levels of triiodothyronine (T(3)), thyroxine (T(4)), free triiodothyronine (FT(3)), free thyroxine (FT(4)), and cortisol were determined at 0, 1, 3, 12, 24, and 48h post-administration of MC-containing extract. Treated fish displayed abnormal behaviors, such as a startle response and disoriented swimming, as well as changes in ventilation rates. Plasma cortisol concentrations of fish in both dose groups significantly increased after administration of extracted MC and remained high throughout the experiment, which suggested that MC elicited a stress response in treated fish. The profiles of cortisol changes in treated fish appeared to be dose dependent, indicating that fish in the high dose group experienced greater MC-induced disturbance. Mortality occurred after 12h in the high dose group. Plasma levels of T(4), T(3), FT(4), and FT(3) did not vary significantly between the control fish. In contrast to this, fish exposed to MC-containing extract showed significant declines in T(3), FT(4), and FT(3) levels in a dose-dependent manner throughout the experiment. Plasma T(4) levels, however, did not vary significantly in the low dose group, whereas they decreased significantly at 48h post injection in the high dose group. This study demonstrates that administration of microcystins-containing extract causes a stress response and reduces the plasma levels of thyroid hormones in crucian carp. These results illustrate that microcystins exerted potent effects on the endocrine system of crucian carp, through activating their hypothalamus-pituitary- interrenal axis and disturbing thyroid function.     

Leaching of cyanogenic glucosides and cyanide from white clover green manure

Use of crops for green manure as a substitute for chemical fertilizers and pesticides is an important approach towards more sustainable agricultural practices. Green manure from white clover is rich in nitrogen but white clover also produces the cyanogenic glucosides (CGs) linamarin and lotaustralin; CGs release toxic hydrogen cyanide (HCN) upon hydrolysis which may be utilized for pest control. We demonstrate that applying CGs in the form of a liquid extract of white clover to large columns of intact agricultural soils can result in leaching of toxic cyanide species to a depth of at least 1m. Although degradation of the CGs during leaching proceeded with half lives in the interval 1.5-35 h depending on soil characteristics, a fraction of the applied CGs (0.9-3.2%) was recovered in the leachate as either CGs or toxic cyanide species. Detoxification of the HCN formed was rapid in soil and leachate from both sandy and loamy soil. However, 30% of the leachate samples exceeded the EU threshold value of 50 micrgl(-1) total cyanide for drinking water and 85% exceeded the US threshold of 5 micrgl(-1) for cyanide chronic ecotoxicity in fresh water. This study demonstrates that even easily degradable natural products present in crop plants as defense compounds pose a threat to the quality of groundwater and surface waters. This aspect needs consideration in assessment of the risk associated with use of crops as green manure to replace chemical fertilizers and pesticides as well as in genetic engineering approaches to design crops with improved pest resistance.     

Pre-concentration and separation of heavy metal ions by chemically modified waste paper gel

Iminodiacetic acid was immobilized on waste paper by chemical modification in order to develop a new type of adsorption gel for heavy metal ions. Adsorption behavior of the gel was investigated for a number of metal ions, specifically Cu(II), Pb(II), Fe(III), Ni(II), Cd(II), and Co(II) at acidic pH. From batch adsorption tests, the order of selectivity was found to be as follows: Cu(II)  Fe(III) > Pb(II) > Ni(II)  Co(II) > Cd(II). Column tests were carried out for pairs of metal ions to understand the separation and pre-concentration behavior of the gel. It was found that mutual separation of Ni(II) from Co(II) and that of Pb(II) from Cd(II) can be achieved at pH 3. Similarly, selective separation of Cu(II) from Cu(II)–Fe(III) and Cu(II)–Pb(II) mixtures at pH 1.5 and 2, respectively, was observed by using this new adsorption gel. In all cases, almost complete recovery of the adsorbed metal was confirmed by elution tests with HCl.     

Removal of thiobencarb in aqueous solution by zero valent iron

A cost-effective method with zero valent iron (ZVI) powder was developed for the purification of thiobencarb (TB)-contaminated water. The removal treatment was performed in the batch system. A sample solution of 10 ml containing 10 microg ml(-1) of TB could be almost completely treated by 100mg of ZVI at 25 degrees C for 12h of treatment time. Since the formation of chloride ion in the aqueous solution during the treatment of TB was observed, the removal of TB with ZVI may contain two processes: reduction (degradation) and adsorption. Because the present treatment for TB is simple, easy handling and cheap, the developed technology with ZVI can contribute to the treatment of agricultural wastewaters.     

Analysis and residue levels of forchlorfenuron (CPPU) in watermelons

This paper describes the application of liquid chromatography-tandem mass spectrometry (LC/MS-MS) for analysis of residues of forchlorfenuron (CPPU), a new plant growth regulator, in watermelons, after a sample preparation step based on the buffered Quick, Easy, Cheap, Effective, Rugged and Safe extraction method. Analytical determinations were carried out in a triple quadrupole system fitted with an electrospray interphase operating in the positive ionisation mode (ESI+). Three simultaneous MS-MS transitions of the quasi-molecular ion m/z 248 (precursor ion) were monitored for data acquisition (248 > 129, 248 > 155, and 248 > 248), using the transition 248 > 129 for quantitation. Recovery studies on watermelons at levels of 1-200 microg/kg, performing five replicates at each level and using bracketing single-level calibration with matrix-matched standards for quantitation, gave forchlorfenuron mean recoveries ranging from 82 to 106% with relative standard deviations (RSD) lower than 18%. The limit of determination was established at 1 microg/kg. The method was applied to evaluate the persistence of forchlorfenuron residues in watermelons grown in plastic greenhouses, after applying an individual spray treatment to the flower ovary at the anthesis stage (45 mu g/flower and 60 mu g/flower for cv "Extazy" and cv "reina de corazones" watermelons, respectively). One month after treatment, 20 "Extazy" watermelon units (1.5-2 kg/unit) and 20 "Reina de corazones" watermelon units (4-5 kg/unit) were collected and analyzed individually. None of the samples contained forchlorfenuron residues higher than 1 microg/kg.     

An Analysis of the Annual and Seasonal Trends of Air Quality Index of Delhi

The Air Quality Index (AQI) is an index for reporting daily air quality. A study on the annual and seasonal variations of Air Quality Index over a period of 9 years (1996-2004) based on daily averaged concentration data of criteria air pollutants has been conducted for Delhi. An attempt has been made to quantify the changes in the AQI on annual and seasonal (winter, summer, monsoon and post monsoon) basis for 9 years. Measurements for the seven monitoring sites (Nizamuddin, Ashok Vihar, Shahzada Baug, Shahadara, Janakpuri, Sirifort and ITO) in Delhi were analysed and trends were also compared amongst these sites. Maximum Operator Function method was used to compute the Air Quality Index of the above areas and percentage variations in different severity class is discussed which provides in depth analysis of the trends. The best air quality was depicted by Shahzada Baug followed by Shahdara, both of these were classified as industrial areas indicating that policy measures relating to the industries in the city during past years have helped in improving the air quality. The air quality in other areas have improved slightly in the span of nine years but still remains critical indicating continued rigorous efforts in this direction. Increased traffic density seems to have resulted into the worst air quality at ITO in the city amongst all the monitoring stations. There is a shift for the worst AQI in the city from winter to summer season in a time span of these nine years. Change of season for worst AQI from Winter to Summer may also be likely due to increased photochemical reactions playing major role with change in the nature of emissions imposed due to different control measures such as CNG implementation, significant shift to LPG in domestic sector etc. calling for a detailed study, those which started after the year 2000. After the year 2000, there is a significant increase in the Nitrogen-dioxide (NO(2)) concentration at all stations. ITO which has shown continuous exponential increase in pollution levels has first time showed a declining AQI trend in the year 2004 and one of the contributing factors could have been the Delhi metro (initiated in 2002) passing through congested neighbouring areas causing traffic decongestion here. In general, the areas which are farthest from metro route viz., Siri-fort, Nizamuddin, Janakpuri etc. did not record declining AQI in 2003 onwards as happened with stations closer to Metro route such as Ashok Vihar and ITO. An attempt has been made to quantify the reasons that lead to the changes in the values of the AQI.