Variability, Speciation and Phytoremediation of Soil Arsenic at Cattle Dip Sites in NSW, Australia

Arsenic (As) contamination of soils is a major environmental problem due to its toxic and carcinogenic nature. Historical use of As-containing pesticides has resulted in the contamination of soils with high and variable concentrations of As in many parts of Australia. Phytoremediation using As-hyperaccumulating ferns can be potentially utilised as an environmental friendly and low-cost remediation technology to phytoextract As from soils at sites containing elevated and varying concentration of As. The spatial variability of total and phosphate-extractable As concentrations was evaluated in soil adjacent to a cattle-dip site located at Wollongbar in northern NSW, Australia. The results from the linear mixed model showed that total (0–0.2 m) and phosphate-extractable (0–0.2, 0.2–0.4 and 0.4–0.6 m depths) As concentrations in the soil adjacent to the dip site varied greatly and increased significantly (P = 0.004–0.048) toward the dip site, indicating that As variability in soil was spatially correlated with distance from the dip. The data suggest that 5 samples should be required to assess the soil contamination level (mean = 826 mg kg–1) and 15 samples would be required to evaluate the effects of phytoremediation of As-contaminated site. The proposed guidelines on sampling requirements are important to estimate the variability in As contamination levels around other cattle-dip sites and to monitor changes in soil As content from phytoremediation activities. Ensuing study compared the phytoremediation potential of Pityrogramma calomelanos var. austroamericana (gold dust fern) against the well-known Pteris vittata (Chinese brake fern) over a 27-month duration grown at the cattle-dip site described earlier. The ferns were planted in January 2009 and harvested following 10, 22 and 27 months of growth. After 10 months of growth (short-term data), P. calomelanos var. austroamericana produced significantly higher frond dry biomass, possessed higher frond As concentration and removed more As in fronds (mean = 130 g plant–1, 887 mg kg–1 and 124 mg plant–1, respectively; P 0.05). It is estimated that P. calomelanos var. austroamericana would take approximately 6 years to decrease mean total As content below the ecological investigation level (EIL; 20 mg kg−1) limit in the surface and subsurface soils, whereas P. vittata would require 13−15 years to achieve this target. The field experiment results suggest that P. calomelanos var. austroamericana is better suited than P. vittata for the phytoremediation of As-contaminated soils under the experimental conditions existing at the site. The potential of mid infrared (MIR) spectroscopy in combination with partial least squares (PLS) regression was investigated to estimate the total As content in a large number of soil samples collected from a highly variable As-contaminated dip site. The MIR-PLS calibration model developed excluding spectral outliers (n = 149) was robust with an acceptable reliability (coefficient of determination; R2c = 0.73; residual prediction deviation; RPDc = 1.94) to estimate total soil As content. The validation of calibration model using a separate set of unknown soil samples (n = 149; validation set) showed R2v and RPDv values of 0.63 and 1.66, respectively. The results indicate an acceptable prediction of total As content in unknown samples, suggesting that MIR-PLS based model is capable of estimating total soil As and possibly be used in certain situations; for example to estimate soil As concentration at a highly variable site, where a large number of samples needs to be analysed. The solid-phase speciation and plant availability of As in contaminated soils was determined using combination of a sequential extraction procedure (SEP), X-ray absorption near edge structure (XANES) spectroscopy and As plant uptake using Brassica juncea as a test plant. Arsenic was found to be predominantly associated with amorphous Fe oxides in arsenate (AsV) form; in few samples As was present in arsenite (AsIII) form. The concentration of As in plant shoots showed significant (P < 0.001−0.05) correlations with the exchangeable As (r = 0.85), and amorphous Fe oxides associated As evaluated by the SEP (r = 0.67) and XANES spectroscopy (r = 0.51). The results suggest that As in these fractions is readily available for plant uptake and may pose potential risk to the environment. Such detailed analysis for As speciation and phytoavailability is vital for the management and rehabilitation of As-contaminated soils.Higher Education Commission of Pakistan, NSW Government through its environmental trust, Australian Synchrotron Research Program, for enabling me to travel to the Australian National Beamline Facility in Tsukuba (Japan) for performing my experiment (Project AS093/ANBF1851

Nanoparticulate Iron Oxide Minerals for Arsenic Removal from Contaminated Water

Groundwater contamination with arsenic (As) is a global environmental and human health problem affecting over 200 million people worldwide, with low to high concentrations of As via drinking well water. Therefore, remediation of As-contaminated water has been under discussion over the last 3 to 4 decades given its highly toxic and carcinogenic properties of As compounds, particularly inorganic arsenite and arsenate species. Several types of sorption techniques have been used to remove As from water such as clay minerals, biochars, metal oxides (e.g., iron oxide minerals), microbes and algae. This chapter provides: (1) insights on the significance of nanoparticulate iron (Fe) oxide minerals (such as nano-ferrihydrite, nano-goethite, nano-magnetite) for their efficiency in the removal of As from contaminated water; (2) develops critical understanding for several As removal methods, compares their potential for As remediation, and critically examines the properties and effectiveness of nanoparticulate Fe oxide minerals to remove As in drinking water or wastewater; and (3) implication of the nanotechnology in remediation of As-rich water. This chapter also elucidated the mechanism of As removal using Fe-oxide nanoparticles in detail

Assessment of potential dietary toxicity and arsenic accumulation in two contrasting rice genotypes : effect of soil amendments

High concentration of arsenic (As) in rice is a serious problem worldwide. Pot experiments were conducted to assess the potential dietary toxicity of arsenic and effect of various soil amendments on arsenic accumulation in rice grains. Two basmati rice genotypes were used to conduct pot experiments using various levels of arsenic (10, 25, 50 and 100 mg kg-1 29 soil). In addition, plants were exposed to soil collected from a well documented arsenic contaminated site. Contrasting results for growth, yield and grain arsenic concentration were obtained for basmati-385 (Bas-385), exhibiting tolerance (56% yield improvement at 10 mg As kg-1 32 ), while genotype BR-1 showed 18% yield decline under same conditions. Furthermore, application ofsoil amendments such as iron (Fe), phosphate (PO4) and farmyard manure (FYM) at 50 mg kg-1,80 kg ha-1 and 10 t ha-1, respectively improved the plant height and biomass in both genotypes. Accumulation of arsenic in rice grain followed a linear trend in BR-1 whereas a parabolic relationship was observed in Bas-385. Both genotypes exhibited a positive response to iron sulfate amendment with significant reduction in grain arsenic concentrations. Regression analysis gave soil arsenic threshold values of 12 mg kg-1 in Bas-385 and 10 mg kg-1 39 in BR-1 for potential dietary toxicity. This study suggests that genotype Bas-385 can be used for safe rice production in areas with soil arsenic contamination up to 12 mg kg-1 41 and that appropriate dose of iron sulfate for soil amendment can be used effectively to reduce translocation of arsenic to rice grai

A review of techniques for detection of movement intention using movement-related cortical potentials

The movement-related cortical potential (MRCP) is a low-frequency negative shift in the electroencephalography (EEG) recording that takes place about 2 seconds prior to voluntary movement production. MRCP replicates the cortical processes employed in planning and preparation of movement. In this study, we recapitulate the features such as signal’s acquisition, processing, and enhancement and different electrode montages used for EEG data recoding from different studies that used MRCPs to predict the upcoming real or imaginary movement. An authentic identification of human movement intention, accompanying the knowledge of the limb engaged in the performance and its direction of movement, has a potential implication in the control of external devices. This information could be helpful in development of a proficient patient-driven rehabilitation tool based on brain-computer interfaces (BCIs). Such a BCI paradigm with shorter response time appears more natural to the amputees and can also induce plasticity in brain. Along with different training schedules, this can lead to restoration of motor control in stroke patients

Efficient removal of norfloxacin using nano zerovalent cerium composite biochar-catalyzed peroxydisulfate

Norfloxacin (NOR), an important antibiotic used for the treatment of different infections which is reportedly causing huge quantity of water pollution and severe environmental issues. In this study, biochar prepared from Phoenix dactylifera roots biomass (PB) and composited with mesoporous nano-zerovalent cerium (nZVCe) was used for treatment of NOR solutions. The various characterization and treatment studies showed successful formation of the nZVCe and PB composite. The nZVCe was found to improve physiological characteristics and catalytic efficiency of PB. The nZVCe/PB composite caused 52% removal of NOR as compared to 23% by the individual PB. The use of peroxydisulfate (PDS) with PB and nZVCe/PB showed further improvement in the removal of NOR and caused 58 and 84% removal efficiencies of NOR by PB/PDS and nZVCe/PB/PDS, respectively. The use of PDS with PB and nZVCe/PB was found to yield ●OH and SO4 ●– which improved degradation of NOR, however, addition of ●OH and SO4 ●– scavengers impeded NOR degradation. The PB was found to have several oxygen functional groups which decomposed PDS into ●OH and SO4 ●–. The nZVCe/PB showed high recovery, reusability, and stability and caused high removal of NOR even at fifth cycle of treatment both in the absence and presence of PDS. The treatment of NOR by nZVCe/PB-catalyzed PDS showed encouraging results under different pH, and varying concentrations of PDS, nZVCe/PB, and NOR as well as in real water samples which suggest potential practical applications of NOR contaminated water. Degradation of NOR resulted into several products and the resulting final product proved to be non-toxic

Synthesis of nitrogen-doped Ceria nanoparticles in deep eutectic solvent for the degradation of sulfamethaxazole under solar irradiation and additional antibacterial activities

© 2020 Elsevier B.V. In this study, highly crystalline, mesoporous, small sized, stable, and efficient nitrogen-doped (N-doped) Ceria nanoparticles were synthesized using deep eutectic solvent (DES) and used for the photocatalytic degradation of sulfamethaxazole (SMX), a widely used human medication and emerging water contaminant. The N-doped Ceria resulted in 96% removal of SMX versus 59% by Ceria under solar irradiation at 150 min time using [SMX]0 = 10 mg/L and [Ceria]0 = [N-doped Ceria]0 = 0.5 g/L. The solar irradiation of the photocatalysts produced [rad]OH which was proved with electron spin resonance (ESR) spectroscopy and radical scavenger studies and the resulting [rad]OH caused the degradation of SMX. The [rad]OH showed high second-order rate constant with SMX, e.g., 4.9 × 109 M−1 s−1. The photocatalytic degradation of SMX was influenced by pH, concentrations of SMX and photocatalysts, inorganic anions, and natural organic matter. The kinetics of the photocatalytic degradation of SMX was found to be pseudo-first-order. The SMX degradation resulted into several products which were identified by UPLC-MS/MS and the resulting products were used to establish degradation pathways of SMX. The synthesized Ceria and N-doped Ceria also showed good antimicrobial activities towards Staphylococcus aureus and Escherichia coli. The treatment of SMX showed high reusability of N-doped Ceria, low leaching of cerium ions into reaction solution, and high decline in toxicity of SMX which suggests high potential of the synthesized nanoparticles towards SMX degradation

Arsenic speciation and biotransformation pathways in the aquatic ecosystem: The significance of algae

© 2020 Elsevier B.V. The contamination of aquatic systems with arsenic (As) is considered to be an internationally-important health and environmental issue, affecting over 115 countries globally. Arsenic contamination of aquatic ecosystems is a global threat as it can enter the food chain from As-rich water and cause harmful impacts on the humans and other living organisms. Although different factors (e.g., pH, redox potential, iron/manganese oxides, and microbes) control As biogeochemical cycling and speciation in water systems, the significance of algal species in biotransformation of As is poorly understood. The overarching attribute of this review is to briefly elaborate various As sources and its distribution in water bodies and factors affecting As biogeochemical behavior in aqueous ecosystems. This review elucidates the intriguing role of algae in biotransformation/volatilization of As in water bodies under environmentally-relevant conditions. Also, we critically delineate As sorption, uptake, oxidation and reduction pathways of As by algae and their possible role in bioremediation of As-contaminated water (e.g., drinking water, wastewater). The current review provides the updated and useful framework for government and water treatment agencies to implement algae in As remediation programs globally

Occurrence of various viruses and recent evidence of SARS-CoV-2 in wastewater systems

Viruses are omnipresent and persistent in wastewater, which poses a risk to human health. In this review, we summarize the different qualitative and quantitative methods for virus analysis in wastewater and systematically discuss the spatial distribution and temporal patterns of various viruses (i.e., enteric viruses, Caliciviridae (Noroviruses (NoVs)), Picornaviridae (Enteroviruses (EVs)), Hepatitis A virus (HAV)), and Adenoviridae (Adenoviruses (AdVs))) in wastewater systems. Then we critically review recent SARS-CoV-2 studies to understand the ongoing COVID-19 pandemic through wastewater surveillance. SARS-CoV-2 genetic material has been detected in wastewater from France, the Netherlands, Australia, Italy, Japan, Spain, Turkey, India, Pakistan, China, and the USA. We then discuss the utility of wastewater-based epidemiology (WBE) to estimate the occurrence, distribution, and genetic diversity of these viruses and generate human health risk assessment. Finally, we not only promote the prevention of viral infectious disease transmission through wastewater but also highlight the potential use of WBE as an early warning system for public health assessment

Lead and copper-induced hormetic effect and toxicity mechanisms in lettuce (Lactuca sativa L.) grown in a contaminated soil

Lead (Pb) and copper (Cu) contamination seriously threatens agricultural production and food safety. This study aims to investigate Pb and Cu induced hormetic effect and toxicity mechanisms in lettuce (Lactuca sativa L.) and establish reliable empirical models of potentially toxic elements (PTEs) transfer in the soil–plant system. The content and distribution of Pb and Cu at subcellular levels in lettuce plants were examined using inductively coupled plasma-mass spectrometry, differential centrifugation and micro-X-ray fluorescence spectroscopy. The PTE-loaded capacity of Pb that ensures food safety was lower than that of Cu in the studied soil, but the PTE-loaded capacity of Pb that limits yield was higher than that of Cu. Lead in lettuce roots mainly accumulated in the cell wall (41%), while Cu mainly accumulated in the vacuoles (46%). The Pb and Cu were primarily distributed in the radicle of lettuce seeds under severe PTE stress, resulting in no seed development. Iron plaque formed on the root surface of lettuce seedlings and sequestered Pb and Cu via chelation. At the same concentration, lettuce was less tolerant to Cu in contaminated soil than Pb due to the higher activity of Cu ions in the soil. Lead was more phytotoxic to lettuce than Cu, however, since the radicle emerged from the seed under severe Cu levels, while it did not protrude under severe Pb levels. The potentially damaging effect of Pb in the visually healthy lettuce appeared to be higher than that of Cu under the same soil contamination level