The sensitivity of PM2.5 source-receptor relationships to atmospheric chemistry and transport in a three-dimensional air quality model

Air quality model simulations constitute an effective approach to developing source-receptor relationships (so-called transfer coefficients in the risk analysis framework) because a significant fraction of particulate matter (particularly PM2.5) is secondary (i.e., formed in the atmosphere) and, therefore, depends on the atmospheric chemistry of the airshed. In this study, we have used a comprehensive three-dimensional air quality model for PM2.5 (SAQM-AERO) to compare three approaches to generating episodic transfer coefficients for several source regions in the Los Angeles Basin. First, transfer coefficients were developed by conducting PM2.5 SAQM-AERO simulations with reduced emissions of one of four precursors (i.e., primary PM, sulfur dioxide (SO2), oxides of nitrogen (NOx), and volatile organic compounds) from each source region. Next, we calculated transfer coefficients using two other methods: (1) a simplified chemistry for PM2.5 formation, and (2) simplifying assumptions on transport using information limited to basin-wide emission reductions. Transfer coefficients obtained with the simplified chemistry were similar to those obtained with the comprehensive model for VOC emission changes but differed for NOx and SOz emission changes. The differences were due to the parameterization of the rates of secondary PM formation in the simplified chemistry. In 90% of the cases, transfer coefficients estimated using only basin-wide information were within a factor of two of those obtained with the explicit source-receptor simulations conducted with the comprehensive model. The best agreement was obtained for VOC emission changes; poor agreement was obtained for primary PM2.5.     

Geometric variability and surface finish of weld zones in Yb:YAG laser welded advanced high strength steels

Laser welding is used for joining advanced high strength steels (AHSS) to improve formability and performance. In this paper, the geometric variability observed in the fusion zones and heat affected zones of several combinations of AHSS (different types, coatings and thicknesses), which were butt welded using a Trumpf TRUDISK 6000^® Yb:YAG laser beam, is presented. The surface texture parameters such as roughness and waviness of laser welds were also measured and correlated with geometric variability. Results indicate that although high quality welds with minimal defects can be obtained using the Yb:YAG laser welding process, there is considerable variation in both the shape and the dimensions of weld zones. The variability increased with an increase in thickness differentials between the sheets being welded. Analysis of the top of the weld surfaces also suggested that aluminum coating on USIBOR samples contributes significantly to increased roughness. An increase in laser power coupled with corresponding increase in welding speed did not impact variability. A fair correlation between the surface roughness and weld region variability exists, although this needs further study.     

Identification and characterization of extracted microplastics from agricultural soil near industrial area: FTIR and X-ray diffraction method

Microplastics have been found in large quantities in agricultural soil and now become a major global issue. Different types of microplastic have adverse effects on agricultural soil. The most widely used method for the extraction of microplastics in agricultural soil is the density floatation method by using saturated NaCl solution. This method includes the pre-digestion of soil samples with H₂O₂ to remove all the organic matter present in the soil. Different types of microplastic particles were extracted and identified by using ATR-FTIR viz polypropylene, polybutylene tetrapthalate, polyethylene, polystyrene, and polyethylene tetrapthalate. The crystalline nature of extracted microplastic was checked by employing XRD analytical technique. Floatation with higher density saturated sodium chloride (NaCl) solution recovered approximately 80% MPs from soil. Floatation methods were found to be effective for extracting microplastics from soils.     

The Synthesis and FTIR, Kinetics and TG/DTG/DTA Study of Inter Penetrating Polymer Networks (IPNs) Derived from Polyurethanes of Glycerol Modified Castor Oil and Cardanol Based Dyes

Interpenetrating polymer networks from agricultural products such as glycerol modified castor oil polyurethanes and cardanol based dyes have not been extensively studied so far. Such polymers were synthesized using benzoyl peroxide as initiator and ethylene glycol dimethacrylate as cross-linker. Characterizations of these polymers were performed by Fourier Transform infra red spectra and thermal analysis techniques such as thermogravimetric analysis, derivative thermogravimetry and differential thermal analysis. The kinetic parameters such as activation energies and orders of reaction were estimated by using Freeman?CAnderson??s method. The effects of changes in polyurethane to dye monomer weight ratio and NCO/OH molar ratio of polyurethanes on the properties of such polymers were studied.     

Toxicological impact of anilofos on some physiological processes of a rice field cyanobacterium Anabaena torulosa

This study deals with the toxicological impact of the herbicide anilofos on photosynthesis, respiration, nitrogen assimilation, and antioxidant system in a diazotrophic rice field cyanobacterium Anabaena torulosa. Treatment of anilofos (1.25, 2.5, and 5?mg?L^?1) affected growth, photosynthetic pigments, photosynthesis, and respiration of the cyanobacterium. Although all the photosynthetic pigments were affected, a maximum effect of the herbicide was observed on phycocyanin (51% reduction) followed by the carotenoids. The effect of the herbicide on photosynthetic pigments resulted in 57% decrease in photosynthetic O₂ evolution. Studies on the photochemical activity demonstrated that both photosystems (PS I and PS II) were affected by the herbicide. Decrease in the photosynthesis rate resulted in decreased nitrogen assimilation, as revealed by reduced nitrate (20%) and ammonium (26%) uptake and decreased activities of nitrogenase (63% decrease) and glutamine synthetase (22% decrease). This ultimately resulted in the reduced growth of the organism. Activities of superoxide dismutase, catalase, and peroxidase in the presence of anilofos increased by 1.8–3.5 times over control cultures. Proline content increased by 1.6 times, while the content of ascorbate decreased slightly. These results indicate that the organism was able to tolerate the herbicide stress by activating oxidative stress defense mechanism.     

Determination of cadmium in water and herbal medicine by Penicillium chrysogenum immobilized on silica gel for flame atomic absorption spectroscopy

Penicillium chrysogenum was immobilized on silica to develop a simple and cost effective method for solid phase extraction of Cd(II) and determination using flame atomic absorption spectrometry (FAAS). The sorbent was characterized by Fourier transform infrared spectroscopy and packed into a column. The conditions for quantitative sorption and desorption of Cd(II) were optimized. The preconcentration factor was 100 while detection limit was 0.61 µg L^?1 with a relative standard deviation of 1.0%. The method was applied for determination of Cd in herbal medicine and tap water.     

Variations in physico-chemical and microbiological characteristics of water during breeding of Cyprinus carpio in a closed hatchery system

Physico-chemical and microbial characteristics of culture water were examined during the induced breeding of Cyprinus carpio in a controlled environmental system. Water temperature, dissolved oxygen, nitrate, phosphate, pH, ammonia nitrogen, total bacterial count, hardness, salinity, carbonate and bicarbonate were estimated before and after spawning and hatching. Average alteration in water pH before and after spawning was 7.91-7.57 and 7.86-7.58 respectively. Total hardness, carbonate and bicarbonate showed insignificant variations. Nitrate, ammonia nitrogen and phosphate contents significantly increased after spawning and hatching p < 0.05. The average increase in nitrate was from 2.94 to 8.62 microg l(-1) after spawning and 3.10 to 8.49 microgl(-1) after hatching. Ammonia nitrogen contents were sharply increased from an average of 0.011 to 1.87 mg l(-1) after spawning and 0.013 to 0.56 mg l(-1) after hatching. The average phosphates increased from 2.59 to 4.15 microg l(-1) after spawning and 2.61 to 4.03 microg l(-1) after hatching. Dissolved oxygen was sharply depleted even after a continuous aeration. Temperature played a vital role during breeding. No successful breeding was observed at a temperature of 17 degrees C or below and 31 degrees C or above. There is a significant association between temperature, spawning and hatching (p < 0.05). By optimizing temperature, the breeding success of this carp was achieved with a statistical significance of p < 0.05. Total bacterial count was significantly increased after spawning and hatching. It was related to the amount of discharge and may cause mass mortality of fish embryo and spawn in a closed hatchery system.     

Synthesis of nanoparticles using microorganisms and their applications: a review

Environmental Chemistry Letters - Nanoparticles synthesis under green conditions has been performed using natural resources to diminish the use of toxic chemicals. For instance, microbial synthesis...     

Integrated process approach for degradation of p-cresol pollutant under photocatalytic reactor using activated carbon/TiO2 nanocomposite: application in wastewater treatment

Environmental Science and Pollution Research - Over the years, biodegradation has been an effective technique for waste water treatment; however, it has its own limitations. In order to achieve a...     

Impact of river flow modification on wetland hydrological and morphological characters

A good number of researchers investigated the impact of flow modification on hydrological, ecological, and geomorphological conditions in a river. A few works also focused on hydrological modification on wetland with some parameters but as far the knowledge is concerned, linking river flow modification to wetland hydrological and morphological transformation following an integrated modeling approach is often lacking. The current study aimed to explore the degree of hydrological alteration in the river and its effect on downstream riparian wetlands by adopting advanced modeling approaches. After damming, maximally 67 to 95% hydrological alteration was recorded for maximum, minimum, and average discharges. Wavelet transformation analysis figured out a strong power spectrum after 2012 (damming year). Due to attenuation of flow, the active inundation area was reduced by 66.2%. After damming, 524.03 km² (48.9% of total pre-dam wetland) was completely obliterated. Hydrological strength (HS) modeling also reported areas under high HS declined by 14% after post-dam condition. Wetland hydrological security state (WSS) and HS matrix, a new approach, are used to explore wetland characteristics of inundation connectivity and hydrological security state. WSS was defined based on lateral hydrological connectivity. HS under critical and stress WWS zones deteriorated in the post-dam period. The morphological transformation was also well recognized showing an increase in area under the patch, edge, and a decrease in the area under the large core area. All these findings established a clear linkage between river flow modification and wetland transformation, and they provided a good clue for managing wetlands.