Applicability of Brassica juncea as a bioindicator for As contamination in soil near the abandoned mine area.

Soil monitoring in abandoned mine areas is important from the perspective of ecological and human health risk. Arsenic (As) is a predominant metalloid contaminant in abandoned mine area and its behavior has been influenced by various soil characteristics. Bioindicator can be a useful tool in terms of testing the extent to which they are uptaken by plants bioavailability. Eighteen soils near the mine tailings dam were collected to investigate the effect of As contamination on As absorption by Brassica juncea. The pH range of the experimental soils was between 4.90 and 8.55, and the total As concentrations were between 34 mg kg-1 and 3017 mg kg-1. The bioavailability of As was evaluated by Olsen method, and B. juncea was cultivated in eighteen soils for 3 weeks. Principal component analysis, correlation, and multiple regression analysis were performed to estimate a significant factor affecting As uptake by B. juncea. All statistical results indicated that As bioavailability in soil is the main factor affecting As uptake in root and shoot of B. juncea. Although translocation process, the amount of As in shoot was exponentially explained by As bioavailability in soil. This result suggests that the contamination and bioavailability of As can be confirmed only by analyzing the shoot of B. juncea, which is be easily found in environmental ecosystem, and implies the applicability of B. juncea as a bioindicator for the monitoring of As contamination and its behavior in soil ecosystem.

Types and concentrations of tire wear particles (TWPs) in road dust generated in slow lanes.

Drivers commonly navigate their vehicles at moderate speeds in proximity to traffic lights. In this study, road dust samples were collected in the vicinity of traffic lights, as well as at a taxi stand (TS) situated between traffic lights, with considerations given to both forward direction (FD) and backward direction (BD). The characterization of tire wear particles (TWPs) in the road dust was meticulously conducted based on particle size. Notably, tire-road wear particles (TRWPs) were conspicuously absent in samples surpassing 500 µm. Furthermore, TRWPs comprised less than 1% of identified particles in the road dust samples of 212-500 µm, with their origin traceable to heavy vehicles rather than passenger cars. The abundance of TRWPs from heavy vehicles exhibited marked variations, with heightened prevalence in the TS and BD samples as opposed to the FD sample. For the samples smaller than 212 µm, the composition of natural rubber (NR) in TWPs demonstrated a diminishing trend with escalating particle size. Conversely, the composition of styrene-butadiene rubber (SBR) exhibited an upward trajectory independent of the sampling site. The NR composition ratio in TWPs followed the order: TS (17-55%) > FD (17-47%) > BD (13-36%), while the SBR composition ratio exhibited the sequence: BD (62-86%) > FD (48-79%) > TS (24-70%). The TWP concentrations in road dust obtained from the TS (0.35-0.82%) were discernibly lower than those in the FD (0.54-1.77%) and BD (0.61-1.29%) samples. Specifically, the average TWP concentrations in road dust samples, falling within the size range of 20-212 µm, were 0.45%, 1.06%, and 0.91% for the TS, FD, and BD samples, respectively. These concentrations were lower than the corresponding values observed in samples collected from a bus stop.

Concentrations of particulate matter (PM2.5) and contributions of tire wear particle to PM2.5 in an indoor parking garage: Comparison with the outside and the differences according to the sampling sites.

Particulate matter (PM) is increasingly affecting the social-economic development of countries. An increase in PM2.5 concentration increases susceptibility to cardiovascular and respiratory diseases and cancer. Tire wear particles (TWP) contribute to airborne PM. In the present work, we investigated the variation in the concentration of TWP of <2.5 µm in aerodynamic diameter (TWP2.5) in an indoor parking garage depending on the sampling sites. PM2.5 samples were collected at four sites in an indoor parking garage of a college campus: the entrance of the parking garage (Ent), the second floor toward the third floor (2F), the front of the parking zone on the second floor (2FP), and the third floor toward the fourth floor (3F). Each PM2.5 sampling was performed for 4 days during the fall season. The PM2.5 concentrations at the 2F and 2FP were similar to the outside PM2.5 concentrations, whereas those at the Ent and 3F were higher than the outside PM2.5 concentrations. The TWP2.5 concentrations in the indoor parking garage were 0.61-0.73 µg/m3. The differences in the TWP2.5 concentrations depending on the sampling sites were due to the differences in traffic volumes. The TWP2.5 concentration at the 2FP was higher than those at the other sampling sites owing to air stagnation and TWPs produced by the high friction when parking and exiting a car in the parking zone. The contributions of TWP2.5 to the PM2.5 concentrations were 3.9-11.7%, in the order of 2FP â‰« Ent > 3F > 2F. A good air ventilation system can be recommended to reduce TWP2.5 concentrations in indoor parking garages.

Characteristics of particulate matter from asphalt pavement and tire of a moving bus through driving tests in city road and proving ground.

Non-exhaust PM emissions from vehicles in real road have been conducted, but heavy vehicles have rarely been tested. In this study, PM2.5 and PM10 samples were directly collected from a tire of a moving bus and the composition was analyzed to investigate the sources of PM emissions. Driving tests were conducted at a proving ground (PG) and a city road (CR). PM2.5 emissions considerably increased when the lateral force of the tire increased and the vehicle accelerated. The PM emission rate was higher in the PG test than in the CR test because of the harsher driving conditions at PG. The emission rates of PM10 in the PG and CR tests were higher than those of PM2.5 by approximately 6 and 11 times, respectively. In the PG and CR tests, the proportions of tire wear particles (TWPs) were 4.9% and 2.1% in the PM2.5 samples, and 6.8% and 8.2% in the PM10 samples, respectively. Furthermore, TWPs with PM (TWPPM) were generated by other sources: secondary production of TWPPM by fragmentation of TWPs and resuspension of TWPPM on the road. The contributions of other sources to TWP2.5 generation were at least 6% and 57% in the PG and CR tests, respectively, whereas that to TWP10 generation was at least 3.5% in the CR test. Iron derived from brake abrasion and mineral particles was observed in the PM samples, and the Fe concentrations were higher in the PM10 samples than in the PM2.5 samples by over 9 and 18 times for the PG and CR tests, respectively. Sulfur sources, such as TWPs, exhaust gas, and bitumen, were observed in the PM samples. Based on our findings, we recommend that road wear particles should be removed from roads to reduce PM emissions upon driving.

Quantification of tire tread wear particle in road dust through pyrolytic technique.

Road dust cotains tire wear particles (TWPs) and a large amount of mineral particles (MPs). Given that tire tread in vehicles is mainly comprised of natural rubber (NR), isoprene and dipentene could be the main pyrogenic products stemmed from the thermolysis of NR. This offers a great chance to quantify the exact mass of TWP in road dust. As such, this study focused on the influence of MPs on the trends in thermolytic behaviors of NR using the resistive furnace (furnance) and Curie point pyrolyzers. This study confirmed that a reliable correlation in line with the formation of isoprene and dipentene could not be realized using the furnace type of a pyrolyzer. This means that employing the furnace type of a pyrolyzer in quantitification of TWPs could not be a viable and approproiate option due to the diverted thermolytic trends of NR due to differences in the heat transfer and adsoprtion of the pyrogenic products triggered by MPs. In the Curie point type of a pyrolyzer, the production rates of isoprene and dipentene were linearly responded to the mass of NR. The ferromagnetic substance in MPs could lead to the thermolytic trend change of NR. Thus, adopting the Curie point type of a pyrolyzer could be a viable option for quantification of TWPs in road dust when the effects of ferromagnetic substance are well neutralized.

Crystallization-based upcycling of iron oxyhydroxide for efficient arsenic capture in contaminated soils.

Arsenic (As)-contaminated soil inevitably exists in nature and has become a global challenge for a sustainable future. Current processes for As capture using natural and structurally engineered nanomaterials are neither scientifically nor economically viable. Here, we established a feasible strategy to enhance As-capture efficiency and ecosystem health by structurally reorganizing iron oxyhydroxide, a natural As stabilizer. We propose crystallization to reorganize FeOOH-acetate nanoplatelets (r-FAN), which is universal for either scalable chemical synthesis or reproduction from natural iron oxyhydroxide phases. The r-FAN with wide interlayer spacing immobilizes As species through a synergistic mechanism of electrostatic intercalation and surface chemisorption. The r-FAN rehabilitates the ecological fitness of As-contaminated artificial and mine soils, as manifested by the integrated bioassay results of collembolan and plants. Our findings will serve as a cornerstone for crystallization-based material engineering for sustainable environmental applications and for understanding the interactions between soil, nanoparticles, and contaminants.

Comparison of polymeric components and tire wear particle contents in particulate matter collected at bus stop and college campus.

Particulate matter (PM2.5) samples were collected at two different places of a college campus (CC) and a bus stop (BS) nearby the college campus. The traffic volume of college campus was very low due to untact classes. Polymeric components and tire wear particle (TWP) contents in the PM2.5 samples were analyzed using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Various polymeric components such as natural rubber (NR), bitumen, saturated hydrocarbons, poly(ethylene terephthalate) (PET), and plant-related particles (PRPs) were observed. NR and bitumen are key components of TWP of bus tire tread and asphalt pavement wear particle (APWP), respectively. The TWP contents in the PM2.5 samples collected at the bus stop were larger than those collected at the college campus. For the same sampling site, the TWP content in the PM2.5 sample collected for higher fine dust concentration in the air was greater than that for lower one. The TWP2.5 concentration in the air for the BS sampling was higher than those for the CC sampling, even when the PM2.5 concentration in the air for the former was lower than those for the latter. It can be concluded that the TWPs and APWPs in the PM2.5 samples collected at the college campus should be transferred mostly from the outside road.

Analysis of Polymeric Components in Particulate Matter Using Pyrolysis-Gas Chromatography/Mass Spectrometry.

Particulate matters (PMs) such as PM10 and PM2.5 were collected at a bus stop and were analyzed using pyrolysis-gas chromatography/mass spectrometry to identify organic polymeric materials in them. The major pyrolysis products of the PM samples were isoprene, toluene, styrene, dipentene, and 1-alkenes. The pyrolysis products generated from the PM samples were identified using reference polymeric samples such as common rubbers (natural rubber, butadiene rubber, and styrene-butadiene rubber), common plastics (polyethylene, polypropylene, polystyrene, and poly(ethylene terephthalate)), plant-related components (bark, wood, and leaf), and bitumen. The major sources of the principal polymeric materials in the PM samples were found to be the abrasion of the tire tread and asphalt pavement, plant-related components, and lint from polyester fabric. The particles produced by the abrasion of the tire tread and asphalt pavement on the road were non-exhaustive sources, while the plant-related components and lint from polyester fabric were inflowed from the outside.

Quantification of tire tread wear particles in microparticles produced on the road using oleamide as a novel marker.

In general, tire tread rubber compounds contain oleamide for improvement of manufacturing processibility, mold release characterization, and abrasion resistance. Tire tread wear particles (TWPs) are one of major contributors to microplastic emissions. In this study, a novel analytical method for quantification of TWP in microparticles produced on the road (road dust, MPRs) was developed by employing oleamide as a new marker. MPRs were collected at bus stops in autumn, winter, and summer seasons. MPRs of 38-63, 63-106, 106-212, and 212-500 µm obtained by size separation were employed for the analysis. Rubber components for bus and passenger car tire tread compounds were identified using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Oleamide was extracted from the MPRs with acetone and was identified using GC/MS. The oleamide concentration was analyzed using GC equipped with flame ionization detector (FID). The TWP contents of the MPRs were determined using the oleamide concentrations and the reference compound formulations. In order to reduce the sampling errors, each experiment was carried out five times and the results were averaged. The TWP contents of the MPRs were 1.4-4.7 wt% and were different according to the sampling seasons and places. The TWP contents were increased by increasing the traffic volume and the temperature.

Label-free detection of γ-aminobutyric acid based on silicon nanowire biosensor.

γ-Aminobutyric acid (GABA) is an important inhibitory neurotransmitter in the central nervous system (CNS), which acts as a major biomarker for neurological disorders such as Parkinson's disease and Meningitis. To this end, the precise measurement of GABA molecule arisen as an important subject for the effective diagnosis and treatment of neurological disorders. However, yet highly sensitive biosensor systems which can analyze a wide range of GABA molecule in a fast response manner have not been reported. In this study, for the first time, a silicon nanowire field-effect transistor (FET) device based immunosensor was developed to detect GABA molecule. Zig-zag shaped silicon nanowires has been fabricated by electron beam lithography and the electrical property p-type FET device was validated through semiconductor analyzer. The optimal immobilizing condition of antibody against GABA molecule was determined by the fluorescent signal measurement. Various concentrations of GABA ranging from 970 fM to 9.7 µM were sensitively measured by conductance change on silicon nanowire-based through the immunoreactions. Further, owing to the ease of miniaturization and label-free system, we believe that the suggested device system has a potential to be utilized for an implantable biosensor to detect neurotransmitter in the brain and can create new opportunities in the field of diagnosis and treatment of neurological disorders.

Label-free nanobiosensor to detect infectious bacterica based on SERS.

Bacteria detection has been important in food, water and air industry to detect contamination or infection. However, conversational bacteria detection method such as culture collection is time-consuming and complicated. In this study, Surface Enhanced Raman Scattering (SERS), one of the most convenient and reliable biosensing techniques, was applied to detect bacteria such as e. coli. First, gold nanoparticles were deposited on Indium Tin Oxide (ITO) substrate by using electrochemical method and confirmed by Scanning Electron Microscope and Ultraviolet-Visible spectroscopy. After antibody against e. coli was immobilized on the gold nanoparticles fabricated on ITO substrate, e. coli samples with different concentrations were applied to the system by antibody-antigen interaction. Then, e. coli was detected by using SERS spectroscopy, demonstrating that the SERS peak intensity at certain raman shift were good relationship with the concentration. In conclusion, this technique could be applied to the biosensor or biochip such as raw milk chip.