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

Van der woude syndrome- a case report

Van der Woude syndrome (VWS) is a rare, autosomal dominant disorder, caused by deletions in the chromosome band 1q32-q41, and characterized by cleft lip or cleft palate, distinctive pits of the lower lips, or both. The most prominent and consistent features of Van der Woude syndrome are oro-facial defects. The oro-facial abnormalities include lower lip pits alone, hypodontia, or isolated cleft lip and cleft palate of varying severity. A case of Van der Woude syndrome, with the typical manifestations in a seven year old male patient is being presented, along with its review of literature

Demonstration of 3-dimensional wide angle laser beam scanner using liquid crystals

Design and demonstration of a versatile liquid crystal-based scanner is shown for steering a laser beam in three dimensions. The scanner consists of a unique combination of digital and analog control polarization-based beamforming optics resulting in both continuous and random fashion beam steering. The design features a novel device biasing method, large aperture beamforming optics, low electrical power consumption, and ultrafine as well as wide angle coarse beam steering. Demonstrations include one, two and three dimensional beam steering with a maximum of 40.92degrees continuous scan, all at 1550 nm. The minimum scanner aperture is 1 cm diameter and uses a combination of ferroelectric and nematic liquid crystals in addition to Rutile crystal birefringent prisms

Lossless Compression of Neuromorphic Vision Sensor Data Based on Point Cloud Representation

Visual information varying over time is typically captured by cameras that acquire data via images (frames) equally spaced in time. Using a different approach, Neuromorphic Vision Sensors (NVSs) are emerging visual capturing devices that only acquire information when changes occur in the scene. This results in major advantages in terms of low power consumption, wide dynamic range, high temporal resolution, and lower data rates than conventional video. Although the acquisition strategy already results in much lower data rates than conventional video, such data can be further compressed. To this end, in this paper we propose a lossless compression strategy based on point cloud compression, inspired by the observation that, by appropriately reporting NVS data in a $(x,y,t)$ tridimensional space, we have a point cloud representation of NVS data. The proposed strategy outperforms the benchmark strategies resulting in a compression ratio up to 30% higher for the considered

Wavelength tunable and broadband variable fiber-optic attenuators using liquid crystals

Fiber-Optic Variable Optical Attenuators (VOAs) are demonstrated using Liquid Crystals (LC) for broadband as well as wavelength tunable applications. Attenuation is achieved by using a beam spoiling approach implemented via electrically reconfigurable non-pixelated no moving parts Nematic LC deflectors. The VOAs feature in-line architecture and polarization insensitive design without the use of bulky polarization splitting and combining optics. The proof-of-concept VOAs in the 1550 nm band demonstrate >30 dB attenuation ranges, low polarization dependent losses and low power consumption. Applications for these VOAs include agile wavelength tunable secure data communications networks and RF sensor systems