Assessing the genotoxic potentials of arsenic in tilapia (Oreochromis mossambicus) using alkaline comet assay and micronucleus test

This experiment was conducted to study the genotoxic potentials of sodium arsenite (NaAsO₂) in freshwater fish Oreochromis mossambicus by using alkaline comet assay and micronucleus (MN) test. Fish were exposed to three different concentrations (3 ppm, 28 ppm and 56 ppm) of arsenic and gill, liver and blood tissue samples were collected after 48 h, 96 h and 192 h of exposure. Arsenic exposure induced DNA damage in all tissues examined in a concentration dependent manner. A significant (p < 0.05) increase in the comet tail DNA (%) of the exposed fish liver, gill, and blood was observed after 48 h and 96 h of exposure, but a decline in DNA damage was recorded in all the tissues at all the three concentrations studied after 192 h of exposure. Liver tissue exhibited significantly (p < 0.05) higher DNA damage at all the concentrations examined, followed by gill and blood. Higher liver tail DNA (51.38 ± 0.21%) refers that it is more prone to injury to arsenic toxicity than the gill and blood. In blood samples arsenic induced micronucleus formation in a concentration dependent manner and highest (5.8 ± 0.46%) value was recorded in 56 ppm after 96 h of exposure, whereas, it was decreased after 192 h of exposure at all the three concentrations of NaAsO₂ examined which refers to the DNA repairing ability of fish to arsenic toxicity. The results of this study depict the genotoxic potentials of arsenic to fish which in turns provide insight on advanced study in aquatic toxicology.     

An on-farm survey of spatial and temporal stratifications of 17β-estradiol concentrations

17β-estradiol (E2) is a natural estrogenic hormone found in animal manure and urine, which may cause endocrine disruption in sensitive organisms. 17β-Estradiol has been widely detected in the environment, and animal agriculture may be an important source. The objectives of this study were to investigate the potential sources and/or spatial and temporal characteristics contributing to detections of E2 at the farm-scale. Soil cores, segmented into 0.15 m increments, were taken down to the water table from four locations (three potential E2 sources and one control) at or around a swine (Sus scrofa domesticus) farm on five different dates between 2006 and 2007. Estradiol was quantified in the soil-water extracts using liquid chromatography-with tandem mass spectrometry (LC/MS/MS) analysis. Estradiol detections were widespread and found in 128 out of 345 extractions (37%). Concentrations ranged from 0 to 1910 ng L⁻¹ (porewater equivalents). A location that received field application of manure had significantly lower E2 concentrations compared to other locations. Also, the spring 2007 E2 concentrations were significantly higher than all other sample dates, perhaps related to climatic and hydrological events. Results suggested E2 was not directly related to manure sources, but was widespread in this environment. Where E2 was detected, highest concentrations favored the upper profile, while the greatest frequency of detections was in the lower profile and near the water table. Detections of E2 were associated with high organic mater contents in the upper profile and high sand contents in the lower profile. The study suggests that E2 is widespread in some soil environments, raising questions as to the source and mechanisms that facilitate its transport and mobility.     

Salt marsh macrophyte Phragmites australis strategies assessment for its dominance in mercury-contaminated coastal lagoon (Ria de Aveiro, Portugal)

Introduction and aims

The dominance of a plant species in highly metal-contaminated areas reflects its tolerance or adaptability potential to these scenarios. Hence, plants with high adaptability and/or tolerance to exceptionally high metal-contaminated scenarios may help protect environmental degradation. The present study aimed to assess the strategies adopted by common reed, Phragmites australis for its dominance in highly mercury-contaminated Ria de Aveiro coastal lagoon (Portugal).

Materials and methods

Both plant samples and the sediments vegetated by monospecific stand of Phragmites australis were collected in five replicates from mercury-free (reference) and contaminated sites during low tide between March 2006 and January 2007. The sediments?? physico-chemical traits, plant dry mass, uptake, partitioning, and transfer of mercury were evaluated during growing season (spring, summer, autumn, and winter) of P. australis. Redox potential and pH of the sediment around roots were measured in situ using a WTW-pH 330i meter. Dried sediments were incinerated for 4?h at 500??C for the estimation of organic matter whereas plant samples were oven-dried at 60??C till constant weight for plant dry mass determination. Mercury concentrations in sediments and plant parts were determined by atomic absorption spectrometry with thermal decomposition, using an advanced mercury analyzer (LECO 254) and maintaining the accuracy and precision of the analytical methodologies. In addition, mercury bioaccumulation and translocation factors were also determined to differentiate the accumulation of mercury and its subsequent translocation to plant parts in P. australis.

Results and conclusions

P. australis root exhibited the highest mercury accumulation followed by rhizome and leaves during the reproductive phase (autumn). During the same phase, P. australis exhibited ??5 times less mercury-translocation factor (0.03 in leaf) when compared with the highest mercury bioaccumulation factor for root (0.14). Moreover, seasonal variations differentially impacted the studied parameters. P. australis?? extraordinary ability to (a) pool the maximum mercury in its roots and rhizomes, (b) protect its leaf against mercury toxicity by adopting the mercury exclusion, and (c) adjust the rhizosphere-sediment environment during the seasonal changes significantly helps to withstand the highly mercury-contaminated Ria de Aveiro lagoon. The current study implies that P. australis has enough potential to be used for mercury stabilization and restoration of sediments/soils rich in mercury as well.     

Development of controlled release formulations of carbofuran and imidacloprid and their bioefficacy evaluation against aphid, Aphis gossypii and leafhopper, Amrasca biguttula biguttula Ishida on potato crop

Controlled release (CR) formulations of carbofuran and imidacloprid were prepared employing polyvinyl chloride and carboxymethyl cellulose (CMC) and their bioefficacy was evaluated against the aphid, Aphis gossypii and leafhopper, Amrasca biguttula biguttula Ishida on potato crop. The CR formulations of carbofuran and imidacloprid provided better or equal control of the pests than commercial formulations. CMC-based formulation provided a superior control of both the pests. The Imida-CMC, which showed the lowest population of leaf hopper (10.50 leafhopper/100 cl), provided significantly superior control among all treatments after 35 days after germination (DAG). The residue of carbofuran and imidacloprid in potato tuber and soils were not detectable at the time of harvesting in any one of the formulations.     

Toxic responses in primary rat hepatocytes exposed with occupational dust collected from work environment of bone-based industrial unit

In this in vitro study we investigated the toxic responses in hepatocytes treated with occupational dust to which workers are exposed in bone-based industrial units. The present study investigated the toxicity mechanism of bone-based occupational dust, from a particular industrial unit, on isolated rat hepatocytes. The hepatocytes were isolated by collagenase perfusion method and cell viability was determined by trypan blue exclusion and MTT [3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay treated with occupational dust at 0.1-1.0 mgmL(-1), for 120 min. The cell viability decreased significantly in a concentration-dependent manner. Dust induced significant membrane damage measured by lactate dehydrogenase (LDH) and glutathione (GSH) release in culture media for 30-, 60- and 120 min treatment duration. The toxicity was found to be correlated with the induction of lipid peroxidation (LPO). In addition, nitric oxide (NO), and hydrogen peroxide (H(2)O(2)) generation by occupational dusts were also found to be time- and concentration-dependent. Over all the present study provides initial evidences for the toxic potential of occupational dust generated in bone-based industries and, therefore, the dust exposure to workers in unorganized industrial units should be controlled.     

Treatment of polychlorinated biphenyls in two surface soils using catalyzed H₂O₂ propagations

Two surface soils contaminated with polychlorinated biphenyls (PCBs) collected from Superfund sites in the New England region of the United States, Fletcher Paints and Merrimack Industrial Metals, were evaluated for field treatment at the bench level using catalyzed H₂O₂ propagations (CHP—modified Fenton’s reagent). The two soils were first evaluated for the potential for in situ treatment based on two criteria: (1) temperature (<40 °C after CHP reagent addition), and (2) hydrogen peroxide longevity (>24 h). In situ CHP remediation was more applicable to the Fletcher soil, while the Merrimack soil was better suited to ex situ treatment based on temperature increases and hydrogen peroxide lifetimes. Using the highest hydrogen peroxide concentrations appropriate for in situ treatment in each soil, PCB destruction was 94% in the Fletcher soil but only 48% in the Merrimack soil. However, 98% PCB destruction was achieved in the Merrimack soil using conditions more applicable to ex situ treatment (higher hydrogen peroxide concentrations with temperatures >40 °C). Analysis of degradation products by gas chromatography/mass spectroscopy showed no detectable chlorinated degradation products, suggesting that the products of PCB oxidation were rapidly dechlorinated and degraded. The results of this research document that the two PCB-contaminated soils studied can be effectively treated using aggressive CHP conditions, and that such a detailed bench study provides important information before implementing field treatment.     

The Effects of Ammonia on SO2 Emissions in a Fluidized Bed Combustor Under Pseudo-Staged Combustion

The reduction of SO₂ by ammonia gas additionduring staged combustion of bituminous coal has beenstudied in a 2 m high fluidized bed combustor of 30 cmstatic bed height and a freeboard height of 100 cm.The coal was introduced to the combustor at 42 cmabove the distributor and the ammonia gas was injectedat 52 cm above the distributor by an uncooledstainless steel injector. Experiments were carriedout to investigate effects of ammonia gas injection onSO₂ emissions of (i) air staged levels, (ii) excess air levels, (iii) primary air factor, PAF(ratio of primary to stoichiometric air), (iv) NH₃:SO₂ molar ratio, and (v) fluidizingvelocity. Experiments were carried out under a newtechnique of air staging called Pseudo-stagedCombustion, maintaining the excess air level andfluidizing velocity between 17 and 70% and between0.7 and 2.0 m sec^-1, respectively. A maximum reduction of92% was obtained at 37% excess air, at NH₃:SO₂ molar ratio of 5.5. The effective NH₃:SO₂ molar ratio was found to be between 3.0 and5.5, which is true for all staging and excess air levels.A greater removal of SO₂ with NH₃ injectionduring staged combustion is probably due to this newstaging technique. The Pseudo-staging reducestemperature through the freeboard and flue for theoccurance of as NH₃ + SO₂ reactions. Thesereactions are reported to be low temperaturereactions. The NH₃ carry over was less than 83 ppm for all operating conditions. The present studydemonstrates that staged combustion coupled withammonia injection can reduce SO₂ emissions.     

Spatiotemporal variation of groundwater quality using integrated multivariate statistical and geostatistical approaches in Amol–Babol Plain,Iran

In recent years, groundwater quality has become a global concern due to its effect on human life and natural ecosystems. To assess the groundwater quality in the Amol–Babol Plain, a total of 308 water samples were collected during wet and dry seasons in 2009. The samples were analysed for their physico-chemical and biological constituents. Multivariate statistical analysis and geostatistical techniques were applied to assess the spatial and temporal variabilities of groundwater quality and to identify the main factors and sources of contamination. Principal component analysis (PCA) revealed that seven factors explained around 75 % of the total variance, which highlighted salinity, hardness and biological pollution as the dominant factors affecting the groundwater quality in the Plain. Two-way analysis of variance (ANOVA) was conducted on the dataset to evaluate the spatio-temporal variation. The results showed that there were no significant temporal variations between the two seasons, which explained the similarity between six component factors in dry and wet seasons based on the PCA results. There are also significant spatial differences (p?>?0.05) of the parameters under study, including salinity, potassium, sulphate and dissolved oxygen in the plain. The least significant difference (LSD) test revealed that groundwater salinity in the eastern region is significantly different to the central and western side of the study area. Finally, multivariate analysis and geostatistical techniques were combined as an effective method for demonstrating the spatial structure of multivariate spatial data. It was concluded that multiple natural processes and anthropogenic activities were the main sources of groundwater salinization, hardness and microbiological contamination of the study area.     

Synthesis,characterization, and systematic studies of a novel aluminum selective chelating resin

A procedure is detailed for the selective analysis of trace aluminum by flame atomic absorption spectrophotometer coupled with off-line column separation and preconcentration. Chelating resin was synthesized by covalent functionalization of Amberlite XAD-16 by 2-(2-hydroxyphenyl) benzoxazole. The modified resin was characterized using FT-IR spectroscopy, energy dispersive x-ray analysis, elemental analysis, thermogravimetric analysis/differential thermal analysis, and minimum energy run. The optimum sorption was at pH 9?±?0.1 with corresponding t _1/2 of only 7 min. Many competitive anions and cations studied did not interfere at all in the selective determination of Al(III), at the optimized conditions. The resin shows maximum sorption capacity of 21.58 mg g^?1 and can be regenerated up to 75 cycles without any discernible capacity loss. The Langmuir isotherm model provides the better correlation of the experimental data (r ²?=?0.999) in comparison to Freundlich isotherm model, while the Scatchard analysis revealed homogeneous binding sites in the chelating resin. Analytical figures of merit were evaluated by accuracy (standard reference materials and recovery experiment), precision (RSD <5 %), and detection limit (2.8 μg L^?1). The applicability was demonstrated by analysis of trace aluminum in biological, environmental, and food samples.     

The depositional setting of the Late Quaternary sedimentary fill in southern Bannu basin,Northwest Himalayan fold and thrust belt,Pakistan

Geostatistical variogram and inversion techniques combined with modern visualization tools have made it possible to re-model one-dimensional electrical resistivity data into two-dimensional (2D) models of the near subsurface. The resultant models are capable of extending the original interpretation of the data to depict alluvium layers as individual lithological units within the 2D space. By tuning the variogram parameters used in this approach, it is then possible to visualize individual lithofacies and geomorphological features for these lithologic units. The study re-examines an electrical resistivity dataset collected as part of a groundwater study in an area of the Bannu basin in Pakistan. Additional lithological logs from boreholes throughout the area have been combined with the existing resistivity data for calibration. Tectonic activity during the Himalayan orogeny uplifted and generated significant faulting in the rocks resulting in the formation of a depression which subsequently has been filled with clay-silt and dirty sand facies typical of lacustrine and flood plain environments. Streams arising from adjacent mountains have reworked these facies which have been eroded and replaced by gravel-sand facies along channels. It is concluded that the sediments have been deposited as prograding fan shaped bodies, flood plain, and lacustrine deposits. Clay-silt facies mark the locations of paleo depressions or lake environments, which have changed position over time due to local tectonic activity and sedimentation. The Lakki plain alluvial system has thus formed as a result of local tectonic activity with fluvial erosion and deposition characterized by coarse sediments with high electrical resistivities near the mountain ranges and fine sediments with medium to low electrical resistivities towards the basin center.