Benefits and limitations of biochar amendment in agricultural soils: A review.

Current agriculture faces multiple challenges due to rapid increases in food demand and environmental concerns. Recently, biochar application in agricultural soils has attracted a good deal of attention. According to literature findings, biochar has proven to play various beneficial roles with respect to the enhancement of crop yield as a fertilizer and soil quality as a soil conditioner. It can further be used to remediate soil pollution as an adsorbent, while supporting the mitigation of greenhouse gases (GHGs) through the expansion of the soil carbon pool. The efficacy of biochar application on agricultural environments is found to be controlled by various factors such as pyrolysis temperature, feed stock, soil type, and biotic interactions. The combined effects of these factors may thus exert a decisive control on the overall outcome. Furthermore, the biochar application can also be proven to be detrimental in some scenarios. This review evaluates both the potential benefits and limitations of biochar application in agriculture soils.

Plant specific emission pattern of biogenic volatile organic compounds (BVOCs) from common plant species of Central India.

In this study, we examined 49 representative plant species of the Achanakmar-Amarkantak Biosphere Reserve (AABR) forest of Central India for emission of a number of biogenic volatile organic compounds (BVOCs). The BVOCs emissions from seven plant species are reported here for the first time. The emission rates of different plant species were ranged from negligible to 80.6 ± 0.82 (µgg-1 h-1). Forty-seven plant species were found to emit isoprene and monoterpenes (23 high emitters, 12 moderate emitters, and 12 low emitters). Dalbergia sissoo showed the maximum total average volatile organic compound (TAVOC) emission rates (80.6 µgg-1 h-1). The percentage composition of monoterpenes was also varied across different plant species. Alpha-pinene (α-pinene) was found as the most dominant monoterpene with about 41.40% of the total monoterpene emission. The highest emission range of α-pinene (7.8 µg g-1 h-1) was observed in Murraya koenigii. Carene was emitted only from two species (i.e., Mangifera indica and Terminalia tomentosa). When the emission rates of present study were compared to previous studies, there were considerable differences even for the same species. The study also reports the emission of BVOCs from Shorea robusta for the first time which is the most dominant plant species of the AABR (covering 60% of the total forest area).

Hazardous and odorous pollutants released from sewer manholes and stormwater catch basins in urban areas.

To learn more about the emission characteristics of odorants released from sewer manholes and stormwater catch basins (SCBs) in an urban environment, we measured the emission concentrations of major odorants including 22 target compounds designated as offensive odorants by the Korean Ministry of Environment (KMOE). All of our measurements were made from urban sewer manholes and SCBs in a highly commercialized location in Seoul, Korea. The results of our study were analyzed to identify the major odorants from such sources and to assess their contribution to odor intensity. The malodor strengths at both types of underground sources were considerably higher in the afternoon than in the morning. The assessment of odor intensity (OI) and odor activity value (OAV) confirmed the dominance of key odorants like H2S, CH3SH, and ammonia along with various volatile fatty acids (VFAs) and phenol. The concentration of these major odorants (H2S, CH3SH, and NH3) exceeded the maximum permissible limit given as the odor prevention law in Korea. As such, significantly high levels of odorants released from these underground sources were greatly distinguished from those seen at above ground locations.

Effects of sorbent materials on the cryofocusing analysis of gaseous reduced sulphur compounds.

The relative performance of different sorbent materials employed in the cryofocusing (e.g. in cold trap (CT) unit) stage was investigated at sub-ambient temperature by the thermal desorption (TD)-gas chromatography (GC)-pulsed flame photometric detector. To this end, the TD-based calibration of five reduced sulphur compounds (RSC: H2S, CH3SH, CS2, DMS and DMDS) and SO2 was carried out via the Peltier cooling system with five types of sorbent combinations such as two single-bed (Tenax TA and Silica gel) plus three multibed types (a combination of either two from the following three sorbents: Tenax TA, Silica gel and Carbopack B). Relative performance of each of all five CT options, if evaluated in terms of response factors for each compound, demonstrated that each CT composition acts as an important criterion to distinguish detection properties between light and heavy sulphur species. Although the relative response of H2S and CH3 SH was systematically distinguishable between the CT types, that of SO2 was the most complicated to interpret. According to this study, the two CT types consisting of Carbopack B and Silica gel (CS-0.4 and CS-0.6) were the optimum choices for sulphur gas analysis in terms of basic QA parameters (sensitivity, reproducibility and linearity).

Constructed wetlands for the removal of organic micropollutants from wastewater: Current status, progress, and challenges.

In this work, the practical utility of constructed wetlands (CWs) is described as a promising treatment option for micropollutants (MPs) in wastewater with the aid of their eco-friendly, low-energy, economically feasible, and ecologically sustainable nature. This paper offers a comprehensive review on CW technology with respect to the key strategies for MP removal such as phytoremediation, substrate adsorption, and microbial degradation. It explores the important factors controlling the performance of CWs (e.g., in terms of configurations, substrates, plant-microbe interactions, temperature, pH, oxygen levels, hydraulic loading rate, and retention time) along with the discussions on the pivotal role of microbial populations in CWs and plant-microbe cooperative remediation dynamics, particularly in relation to diverse organic MP patterns in CWs. As such, this review aims to provide valuable insights into the key strategies for optimizing MP treatment and for enhancing the efficacy of CW systems. In addition, the process-based models of constructed wetlands along with the numerical simulations based on the artificial neural network (ANN) method are also described in association with the data exploratory techniques. This work is thus expected to help open up new possibilities for the application of plant-microbe cooperative remediation approaches against diverse patterns of organic MPs present in CWs.

Major odorants released as urinary volatiles by urinary incontinent patients.

In this study, volatile urinary components were collected using three different types of samples from patients suffering from urinary incontinence (UI): (1) urine (A); (2) urine + non-used pad (B); and (3) urine + used pad (C). In addition, urine + non-used pad (D) samples from non-patients were also collected as a reference. The collection of urinary volatiles was conducted with the aid of a glass impinger-based mini-chamber method. Each of the four sample types (A through D) was placed in a glass impinger and incubated for 4 hours at 37 °C. Ultra pure air was then passed through the chamber, and volatile urine gas components were collected into Tedlar bags at the other end. These bag samples were then analyzed for a wide range of VOCs and major offensive odorants (e.g., reduced sulfur compounds (RSCs), carbonyls, trimethylamine (TMA), ammonia, etc.). Among the various odorants, sulfur compounds (methanethiol and hydrogen sulfide) and aldehydes (acetaldehyde, butylaldehyde, and isovaleraldehyde) were detected above odor threshold and predicted to contribute most effectively to odor intensity of urine incontinence.

Existence of nodal-arc and its evolution into Weyl-nodes in the presence of spin-orbit coupling in TaAs & TaP.

In this work, we report the existence ofnodal-arc, which acts as the building block of all the nodal-rings in TaAs & TaP. Thisnodal-arcis found to be capable of generating all the nodal-rings in these materials upon the application of space-group symmetry operations including time-reversal symmetry. The arcs are obtained to be dispersive with the energy spread of ∼109 (∼204) meV in TaAs (TaP). Also, the orbitals leading to bands-inversion and thus the formation ofnodal-arcsare found to be Ta-5d& As-4p(P-3p) in TaAs (TaP). The area of nodal-rings is found to be highly sensitive to the change in hybridization-strength, where the increase in hybridization-strength leads to the decrease in the area of nodal-rings. In the presence of spin-orbit coupling (SOC), all the points on these arcs get gaped-up and two pairs of Weyl-nodes are found to evolve from them. Out of the two pair, one is found to be situated close to the joining point of the two arcs forming a ring. This causes the evolution of each nodal-ring into three pairs of Weyl-nodes. The coordinates of these Weyl-nodes are found to be robust to the increase in SOC-strength from ∼ 0.7-3.5 eV. All the results are obtained at thefirst-principlelevel. This work provides a clear picture of the existence of nodal-arc due to accidental degeneracy and its evolution into Weyl-nodes under the effect of SOC.

Environmental Factors Affecting Monoterpene Emissions from Terrestrial Vegetation.

Monoterpenes are volatile organic compounds that play important roles in atmospheric chemistry, plant physiology, communication, and defense. This review compiles the monoterpene emission flux data reported for different regions and plant species and highlights the role of abiotic environmental factors in controlling the emissions of biogenic monoterpenes and their emission fluxes for terrestrial plant species (including seasonal variations). Previous studies have demonstrated the role and importance of ambient air temperature and light in controlling monoterpene emissions, likely contributing to higher monoterpene emissions during the summer season in temperate regions. In addition to light and temperature dependence, other important environmental variables such as carbon dioxide (CO2), ozone (O3), soil moisture, and nutrient availability are also known to influence monoterpene emissions rates, but the information available is still limited. Throughout the paper, we identify knowledge gaps and provide recommendations for future studies.

Evaluation of the solid-phase extraction (SPE) cartridge method in combination with thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) for the analysis of different VOCs in liquid matrices in varying pH conditions.

In this study, the solid-phase extraction (SPE) method combined with thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) method is evaluated for the analysis of liquid-phase volatile organic compounds (LVOCs). Calibration experiments were performed on a number of polar and nonpolar LVOCs (including aromatic compounds, ester, ketones, and alcohol) as a function of solution pH. If the relative sensitivity of the SPE-TD-GC-MS method is compared between different VOCs across a wide range of pH (1, 4, 7, 10, and 13), optimum sensitivities for most VOCs are derived at the neutral pH. However, there were some exceptions to the general trend with the maximum sensitivity occurring either at a moderately basic pH (methyl isobutyl ketone and butyl acetate) or extremely acidic conditions (isobutyl alcohol). It was also noticed that the relative ordering of sensitivity was changed, as the pH conditions of the solution vary. The use of internal standard (IS: chlorobenzene) resulted in a notable improvement in both relative sensitivity and reproducibility for most compounds.

Volatile Organic Compounds in Ambient Air at Four Residential Locations in Seoul, Korea.

To investigate the environmental behavior of volatile organic compounds (VOCs) in urban areas, their concentrations were measured at four urban monitoring sites (namely, N, S, E, and W) in Seoul, Korea (February to December 2009). A total of 27 compounds were quantified that consist of four chemical groups: aromatic (AR), halogenated aromatic, halogenated paraffin, and halogenated olefin. Results were evaluated by focusing on these four functional groups just mentioned and their summation term as total VOC (TVOC) along with several individual species (mainly AR species, that is, benzene, toluene, ethylbenzene, and xylene). The highest concentration of chemical groups was found from AR (71.1±42.1 ppbC), while that for individual species confirmed the dominance of toluene (7.48±3.88 ppb). The analysis of spatial distribution indicated that high TVOC levels were recorded at sites N and W, while it was not so significant such as S and E in terms of TVOC budget. Seasonal variation of these VOCs was characterized by the peak values in December to reflect the combined effects of pronounced source activities and meteorological conditions. Analysis of spatial variations in VOC levels between the four urban sites indicated that their distributions are tightly affected by local source processes in each area.

Analysis of volatile organic compounds released during food decaying processes.

A number of volatile organic compounds (VOCs) including acetone, methyl ethyl ketone, toluene, ethylbenzene, m,p-xylene, styrene, and o- xylene released during food decaying processes were measured from three types of decaying food samples (Kimchi (KC), fresh fish (FF), and salted fish (SF)). To begin with, all the food samples were contained in a 100-mL throwaway syringe. These samples were then analyzed sequentially for up to a 14-day period. The patterns of VOC release contrasted sharply between two types of fish (FF and SF) and KC samples. A comparison of data in terms of total VOC showed that the mean values for the two fish types were in the similar magnitude with 280 ± 579 (FF) and 504 ± 1,089 ppmC (SF), while that for KC was much lower with 16.4 ± 7.6 ppmC. There were strong variations in VOC emission patterns during the food decaying processes between fishes and KC that are characterized most sensitively by such component as styrene. The overall results of this study indicate that concentration levels of the VOCs differed significantly between the food types and with the extent of decaying levels through time.

Global distribution of microplastic contaminants in aquatic environments and their remediation strategies.

This review describes the occurrence and distribution of microplastics in freshwater and marine environments in recent years (2017-2022). Use of microplastics often results in contamination of aquatic environments, threatens biodiversity, and creates the need for environmental remediation. Such remediation strategies can involve primary, secondary, and tertiary treatments. Tertiary treatment is a frequent research subject due to its high efficiency and the possibility for advancements and enhancements. This study discusses tertiary treatments with remediation efficiencies of 95% and greater and their advantages, disadvantages, and future perspectives. Biochar-mediated remediation of microplastics is an effective method that may be able to achieve efficiencies approaching 100%. The study concludes by exploring methods of removing microplastics, including constructed wetlands and biochar, which offer high efficiency. PRACTITIONER POINTS: Tertiary treatments are an effective microplastic remediation strategy applicable succeeding secondary or primary treatments or as an individual remediation strategy. Biochar is a highly efficient adsorbent for microplastic remediation from aquatic environment with eco-friendly aspect and reusability. Modifications in tertiary treatments and enhancement in remediation efficiency are still a subject of research for future studies.

An evaluation of volatile compounds released from containers commonly used in circulation of sports beverages.

In an effort to identify and quantify important volatile organic compounds (VOCs) released from sports beverage containers commonly used for storage and distribution, three brands of sports beverages with poly ethylene terephthalate (PET) and metal cans were analyzed through headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). Out of 80 volatile compounds identified from all container types, I-limonene recorded the highest concentration (34.3-118 pmol mol(-1)) along with 12 other VOCs detected most frequently (more than 3 out of all 6 products) such as 2-methyl-6-methylene-2,7-octadiene, alpha-terpineol, decanaldehyde, and p-isopropyltoluene. When each container was filled up with water and analyzed after a long-term storage (49 days), a total of 14 VOCs were detected. According to our analysis, all the VOCs detected from either beverage or container materials were below the safety limits prescribed previously by diverse agencies. However, an extension of these analyses may be necessary for other beverage types, as certain VOCs can be migrated from container materials.

A combined application of thermal desorber and gas chromatography to the analysis of gaseous carbonyls with the aid of two internal standards.

In this study, a series of GC calibration experiments were conducted to examine the feasibility of the thermal desorption approach for the quantification of five carbonyl compounds (acetaldehyde, propionaldehyde, butyraldehyde, isovaleraldehyde, and valeraldehyde) in conjunction with two internal standard compounds. The gaseous working standards of carbonyls were calibrated with the aid of thermal desorption as a function of standard concentration and of loading volume. The detection properties were then compared against two types of external calibration data sets derived by fixed standard volume and fixed standard concentration approach. According to this comparison, the fixed standard volume-based calibration of carbonyls should be more sensitive and reliable than its fixed standard concentration counterpart. Moreover, the use of internal standard can improve the analytical reliability of aromatics and some carbonyls to a considerable extent. Our preliminary test on real samples, however, indicates that the performance of internal calibration, when tested using samples of varying dilution ranges, can be moderately different from that derivable from standard gases. It thus suggests that the reliability of calibration approaches should be examined carefully with the considerations on the interactive relationships between the compound-specific properties and the operation conditions of the instrumental setups.

Determination of hazardous VOCs and nicotine released from mainstream smoke by the combination of the SPME and GC-MS methods.

In this study, the contents of nicotine and volatile organic compounds (VOCs) in mainstream smoke (MSS) were analyzed using samples of four cigarette types consisting of two common brands (R and E) with full (F) and light (L) flavor, coded with R-F, R-L, E-F, and E-L. These cigarettes were also analyzed after removing the filter portions with the assignment of a new sample code of (N) as the third letter (e.g., R-L-N). A total of 44 VOCs (including nicotine) were quantified by the combination of the SPME and GC-MS methods. Out of the 44 VOCs, 10 were identified as hazardous air pollutants listed by the U.S. EPA, while their concentrations exceeded the reference exposure limits set by various agencies. A clear distinction was apparent in the concentration levels of VOCs between different brands or between full and light flavors. Nicotine concentrations varied greatly between different cigarettes types of the R brand, whereas such changes were insignificant in the counterpart E brand. This thus suggests that light-flavor cigarettes do not necessarily guarantee low doses of carcinogens (and tar) than regular cigarettes, as their differences can be balanced by the inhaling behavior of the smoker.

Analytical bias among different gas chromatographic approaches using standard BTX gases and exhaust samples.

In this study, the analytical compatibility of the gas chromatographic (GC) approach was evaluated through a cross-calibration exercise. To this end, three aromatic volatile organic compounds (VOCs: benzene, toluene, and p-xylene (BTX)) were simultaneously analyzed with four individual instrumental setups (type I = GC with MS plus solid phase microextraction (SPME) method, II = GC with flame ionization detection (FID) plus SPME, III = fast GC-FID plus SPME, and IV = GC-FID plus air server/thermal desorption (AS/TD) method). A comparison of basic quality assurance (QA) data revealed considerable differences in DL values among the methods with moderate variabilities in the intercompound sensitivity. In light of the differences in detection properties, the analytical bias involved for each methodological approach was assessed by the relative relationship between analytes and basic operating conditions. The results suggest that the analysis of environmental samples at ultra-low concentration levels (at or below ppb level) can be subject to diverse sources of bias. Although detection properties of target compounds seem to be affected by the combined effects of various factors, changes in the sample concentration levels were seen to be the most consistent under the experimental setups analyzed in this study.

BBQ charcoal as an important source of mercury emission.

In this study, the environmental significance of mercury emission has been investigated with respect to the use of the barbecue (BBQ) charcoal. For this purpose, emission gas samples collected from a total of 11 barbecue charcoal products commonly available in the Korean market were analyzed. All of these products consist of both domestic (4 types) and imported products (7 types from three countries). The emission concentration of Hg varied widely from sample to sample ranging from 114 to 496ngm(-3). The amount of Hg emission appeared to be affected by the diverse nature of raw materials and/or the processes involved in their production. In light of the recent reference exposure limits (REL) of Hg, it can be a potential threat to human health. As such, a proper regulation is desirable from a toxicological viewpoint to reduce the potential risk associated with the use of BBQ charcoal.

Heavy metal pollution induced due to coal mining effluent on surrounding aquatic ecosystem and its management through naturally occurring aquatic macrophytes.

Three aquatic plants Eichhornia crassipes, Lemna minor and Spirodela polyrhhiza were used in laboratory for the removal of heavy metals from the coal mining effluent. Plants were grown singly as well as in combination during 21 days phytoremediation experiment. Results revealed that combination of E. crassipes and L. minor was the most efficient for the removal of heavy metals while E. crassipes was the most efficient in monoculture. Significant correlations between metal concentration in final water and macrophytes were obtained. Translocation factor i.e. ratio of shoot to root metal concentration revealed that metals were largely retained in the roots of aquatic macrophytes. Analytical results showed that plant roots have accumulated heavy metals approximately 10 times of its initial concentration. These plants were also subjected to toxicity assessment and no symptom of metal toxicity was found therefore, this method can be applied on the large scale treatment of waste water where volumes generated are very high and concentrations of pollutants are low.

The Relative Performance of NDIR-based Sensors in the Near Real-time Analysis of CO2 in Air.

In this study, the reliability of NDIR-based sensors was explored by evaluatingthe comparability between measurement systems in the near real-time analysis of CO2. Forthis purpose, replicate analyses were performed using sensors of two different model types(H-550 and B-530, ELT Company, Korea). Three replicate data of each sensor typecollected continuously by side-by-side analysis in three second intervals (a duration of 304hour) were evaluated for the relative performance of NDIR sensors. The reproducibility ofsensors, when assessed by relative standard error (RSE %) values of all sensor units,showed moderate changes with time with the overall mean of 2.33%. When CO2measurements from all NDIR sensor units were evaluated by correlation analysis, theresults showed strong comparability, regardless of the model type. The overall results ofthis study suggest that NDIR sensors are reliable enough to produce highly comparabledata at least in a relative sense.

Use of a Dynamic Enclosure Approach to Test the Accuracy of the NDIR Sensor: Evaluation Based on the CO2 Equilibration Pattern.

As part of a quality assurance (QA) study for sensor systems, an enclosureapproach is applied to assess the accuracy of non-dispersive infrared (NDIR)-based CO2sensors. To examine the performance of the sensor system, an enclosure chambercontaining six sensor units of the two model types (B-530 and H-500) was equilibratedwith calibrated CO2 standards at varying concentration levels. Initially, the equilibrationpattern was analyzed by CO2-free gas (0 ppm) at varying flow rates (i.e., 100, 200, 500, and1000 mL min-1). Results of the test yielded a highly predictable and quantifiable empiricalrelationship as a function of such parameters as CO2 concentration, flow rate, andequilibration time for the enclosure system. Hence, when the performance of the NDIR-method was evaluated at other concentrations (i.e., 500 and 1000 ppm), all the sensor unitsshowed an excellent compatibility, at least in terms of the correlation coefficients (r >0.999, p = 0.01). According to our analysis, the NDIR sensor system seems to attain anoverall accuracy near the 5% level. The relative performance of the NDIR sensor for CO2analysis is hence comparable with (or superior to) other methods previously investigated.The overall results of this study indicate that NDIR sensors can be used to provide highlyaccurate and precise analyses of CO2 both in absolute and relative terms.