Phyto-management of Cr-contaminated soils by sunflower hybrids: physiological and biochemical response and metal extractability under Cr stress

Environmental Science and Pollution Research - Chromium (Cr) is a biologically non-essential, carcinogenic and toxic heavy metal. The cultivation of Cr-tolerant genotypes seems the most favorable...     

Sustaining Asia's groundwater boom: An overview of issues and evidence

This article suggests that Asia’s groundwater socio‐ecology is at an impasse. Rapid growth in groundwater irrigation in South Asia and the North China plains during the period 1970–95 has been the main driver of the agrarian boom in these regions. India, Pakistan, Bangladesh and China account for the bulk of the world’s use of groundwater in agriculture. On the plus side, groundwater development has provided sustenance to agrarian economies and millions of rural livelihoods. On the downside, it has created chronic problems of resource depletion and quality deterioration. While problems of groundwater depletion, pollution and quality deterioration are indeed serious, so are the consequences of the degradation of the resource for those that have come to precariously depend upon groundwater irrigation. Three problems currently afflict groundwater use: depletion due to overdraft; water logging and salinization; and pollution due to agricultural, industrial and other human activity. The pathology of the decline in groundwater socio‐ecology reflects a remarkably similar pattern across regions. The critical issue for Asia now is: what might be done to sustain and revive these groundwater socio‐ecologies vital to the region’s economy? This article reviews a variety of techno‐institutional approaches. However, transposing lessons from the industrialized world uncritically in the Asian context may not work. A more nuanced understanding of the peculiarities of Asia’s groundwater socio‐ecology is needed.     

Impacts of continuously regenerating trap and particle oxidation catalyst on the NO2 and particulate matter emissions emitted from diesel engine

Two continuously regenerating diesel particulate filter (CRDPF) with different configurations and one particles oxidation catalyst (POC) were employed to perform experiments in a controlled laboratory setting to evaluate their effects on NO₂, smoke and particle number emissions. The results showed that the application of the after-treatments increased the emission ratios of NO₂/NO_x significantly. The results of smoke emissions and particle number (PN) emissions indicated that both CRDPFs had sufficient capacity to remove more than 90% of total particulate matter (PM) and more than 97% of solid particles. However, the POC was able to remove the organic components of total PM, and only partially to remove the carbonaceous particles with size less than 30 nm. The negligible effects of POC on larger particles were observed due to its honeycomb structure leads to an inadequate residence time to oxidize the solid particles or trap them. The particles removal efficiencies of CRDPFs had high degree of correlations with the emission ratio of NO₂/NO_x. The PN emission results from two CRDPFs indicated that more NO₂ generating in diesel oxidation catalyst section could obtain the higher removal efficiency of solid particles. However this also increased the risk of NO₂ exposure in atmosphere.     

Proteomics study of Southern Punjab Pakistani cobra (Naja naja: formerly Naja naja karachiensis) venom

Because of the potential of significant geographic variation in the compositions of snake venoms, much insight can be gained by examining individuals originating from diverse locations, and detailed characterization of any species can only be done by including animals from the entire range. Pakistani N. naja (formerly N. naja karachiensis) venom was decomplexed by applying diverse techniques and found a concoction of proteins (a total of 43 venomous proteins comprising 11 super families) from 6 to 200 kilodaltons in size. Among them three finger toxins (58%), phosphoplipses A₂ (19%), snake venom metalloproteinases (5%), l-amino acid oxidases (5%), helvepryns (3%), vespryns (2%), cobra venom factor (2%), 5′-nucleotidases (2%), venom nerve growth factor (2%), and Kunitz type serine protease inhibitor (2%) were included. It is the first report that this venom possesses significantly higher percentage of three finger toxins belonging to the cytotoxins (32% overall) and α‐neurotoxins (32% overall, predominately long chain neurotoxins, 24% overall) compared to N. naja from other geographic locations. Better understanding of intraspecific variations in venom can improve the development of location-specific anti-venoms. Furthermore, this pool of diverse toxins could potentially be a source of novel drug candidates for the treatment of muscarinic acetylcholine receptors mediated nervous disorders.     

Salt-induced land and water degradation in the Aral Sea basin: A challenge to sustainable agriculture in Central Asia

Expansion of irrigated agriculture in the Aral Sea Basin in the second half of the twentieth century led to the conversion of vast tracks of virgin land into productive agricultural systems resulting in significant increases in employment opportunities and income generation. The positive effects of the development of irrigated agriculture were replete with serious environmental implications. Excessive use of irrigation water coupled with inadequate drainage systems has caused large‐scale land degradation and water quality deterioration in downstream parts of the basin, which is fed by two main rivers, the Amu‐Darya and Syr‐Darya. Recent estimates suggest that more than 50% of irrigated soils are salt‐affected and/or waterlogged in Central Asia. Considering the availability of natural and human resources in the Aral Sea Basin as well as the recent research addressing soil and water management, there is cause for cautious optimism. Research‐based interventions that have shown significant promise in addressing this impasse include: (1) rehabilitation of abandoned salt‐affected lands through halophytic plant species; (2) introduction of 35‐day‐old early maturing rice varieties to withstand ambient soil and irrigation water salinity; (3) productivity enhancement of high‐magnesium soils and water resources through calcium‐based soil amendments; (4) use of certain tree species as biological pumps to lower elevated groundwater levels in waterlogged areas; (5) optimal use of fertilizers, particularly those supplying nitrogen, to mitigate the adverse effects of soil and irrigation water salinity; (6) mulching of furrows under saline conditions to reduce evaporation and salinity buildup in the root zone; and (7) establishment of multipurpose tree and shrub species for biomass and renewable energy production. Because of water withdrawals for agriculture from two main transboundary rivers in the Aral Sea Basin, there would be a need for policy level interventions conducive for enhancing interstate cooperation to transform salt‐affected soil and saline water resources from an environmental and productivity constraint into an economic asset.     

CO2 separation by supported liquid membranes synthesized with natural deep eutectic solvents

Environmental Science and Pollution Research - Betaine-based natural deep eutectic solvents (NADESs), a new class of green solvents, were immobilized into a porous polyvinylidene fluoride (PVDF)...     

Mercury removal from aqueous solution using petal-like MoS2 nanosheets

• Synthesized few-layered MoS₂ nanosheets via surfactant-assisted hydrothermal method. • Synthesized MoS₂ nanosheets show petal-like morphology. • Adsorbent showed 93% of mercury removal efficiency. • The adsorption of mercury is attributed to negative zeta potential (-21.8 mV). Recently, different nanomaterial-based adsorbents have received greater attention for the removal of environmental pollutants, specifically heavy metals from aqueous media. In this work, we synthesized few-layered MoS₂ nanosheets via a surfactant-assisted hydrothermal method and utilized them as an efficient adsorbent for the removal of mercury from aqueous media. The synthesized MoS₂ nanosheets showed petal-like morphology as confirmed by scanning electron microscope and high-resolution transmission electron microscopic analysis. The average thickness of the nanosheets is found to be about 57 nm. Possessing high stability and negative zeta potential makes this material suitable for efficient adsorption of mercury from aqueous media. The adsorption efficiency of the adsorbent was investigated as a function of pH, contact time and adsorbent dose. The kinetics of adsorption and reusability potential of the adsorbent were also performed. A pseudo-second-order kinetics for mercury adsorption was observed. As prepared MoS₂ nanosheets showed 93% mercury removal efficiency, whereas regenerated adsorbent showed 91% and 79% removal efficiency in the respective 2^nd and 3^rd cycles. The adsorption capacity of the adsorbent was found to be 289 mg/g at room temperature.     

Unregulated emissions from a diesel engine equipped with vanadium-based urea-SCR catalyst

The present work is aimed at the study of number-size distribution of particles,volatile organic compounds(VOCs),and carbonyl compounds(CC) or carbonyls emitted from a 4-cylinder turbocharged diesel engine equipped with a vanadium-based urea selective catalytic reduction catalyst.The engine was run on an electric dynamometer in accordance with the European steady-state cycle.Pollutants were analyzed using an electric low pressure impactor,a gas chromatograph/mass spectrometer,and a high performance liquid chromatography system for the number-size distribution of particles,VOCs,and CC emissions,respectively.Experimental results revealed that total number of particles were decreased,and their number-size distributions were moved from smaller sizes to larger sizes in the presence of the catalyst.The VOCs were greatly reduced downstream of the catalyst.There was a strong correlation between the conversion of styrene and ethyl benzene.The conversion rate of benzene increased with increase of catalyst temperature.Formaldehyde,acetaldehyde,acrolein and acetone were significantly reduced,resulting in a remarkable abatement in carbonyls with the use of the vanadium-based urea-SCR system.     

Characterization of polycyclic aromatic hydrocarbon emissions from diesel engine retrofitted with selective catalytic reduction and continuously regenerating trap

Two after treatment units, selective catalytic reduction (SCR) and continuously regenerating trap (CRT), were independently retrofitted to a diesel engine, with the objective to investigate their impact on the conversion/reduction (CR) of polycyclic aromatic hydrocarbons (PAHs). The experiments were conducted under the European steady state cycle (ESC) first without any retrofits to get baseline emissions, and then with SCR and CRT respectively, on the same engine. The particulate matter (PM)-phase PAHs were trapped in fiberglass filters, whereas gas-phase PAHs were collected in cartridges, and then analyzed using a gas chromatograph-mass spectrometer (GC-MS). Both PM-phase and gas-phase PAHs were greatly reduced with CRT showing respective CR of 90.7% and above 80%, whereas only gas-phase PAHs were abated in the case of SCR, with CR of above 75%. Lower molecular weight (LMW) PAHs were in abundance, while naphthalene exhibited a maximum relative contribution (RC) to LMW-PAHs for all three cases. Further, the CR of naphthalene and anthracene were increased with increasing catalyst temperature of SCR, most likely due to their conversion to solid particles. Moreover, the Benzo[a]Pyrene equivalent (BaP_eq) of PAHs was greatly reduced with CRT, owing to substantial reduction of total PAHs.     

Spatial modeling of rat bites and prediction of rat infestation in Peshawar valley using binomial kriging with logistic regression

In this study, we propose to develop a geostatistical computational framework to model the distribution of rat bite infestation of epidemic proportion in Peshawar valley, Pakistan. Two species Rattus norvegicus and Rattus rattus are suspected to spread the infestation. The framework combines strengths of maximum entropy algorithm and binomial kriging with logistic regression to spatially model the distribution of infestation and to determine the individual role of environmental predictors in modeling the distribution trends. Our results demonstrate the significance of a number of social and environmental factors in rat infestations such as (I) high human population density; (II) greater dispersal ability of rodents due to the availability of better connectivity routes such as roads, and (III) temperature and precipitation influencing rodent fecundity and life cycle.