Remediation of RDX- and HMX-contaminated groundwater using organic mulch permeable reactive barriers

Organic mulch is a complex organic material that is typically populated with its own consortium of microorganisms. The organisms in mulch breakdown complex organics to soluble carbon, which can then be used by these and other microorganisms as an electron donor for treating RDX and HMX via reductive pathways. A bench-scale treatability study with organic mulch was conducted for the treatment of RDX- and HMX-contaminated groundwater obtained from a plume at the Pueblo Chemical Depot (PCD) in Pueblo, Colorado. The site-specific cleanup criteria of 0.55 ppb RDX and 602 ppb HMX were used as the logical goals of the study. Column flow-through tests were run to steady-state at the average site seepage velocity, using a 70%:30% (vol.:vol.) mulch:pea gravel packing to approach the formation's permeability. Significant results included: (1) Complete removal of 90 ppb influent RDX and 8 ppb influent HMX in steady-state mulch column effluent; (2) pseudo-first-order steady-state kinetic rate constant, k, of 0.20 to 0.27 h(-1) based on RDX data, using triplicate parallel column runs; (3) accumulation of reduced RDX intermediates in the steady-state column effluent at less than 2% of the influent RDX mass; (4) no binding of RDX to the column fill material; and (5) no leaching of RDX, HMX or reduction intermediates from the column fill material. The results of the bench-scale study will be used to design and implement a pilot-scale organic mulch/pea gravel permeable reactive barrier (PRB) at the site.     

Mercury chloride toxicity in human erythrocytes: enhanced generation of ROS and RNS,hemoglobin oxidation,impaired antioxidant power,and inhibition of plasma membrane redox system

Environmental Science and Pollution Research - Mercury is among the most toxic heavy metals and a widespread environmental pollutant. Mercury chloride (HgCl2) is an inorganic compound of mercury...     

Graphene and its derivatives: synthesis,modifications, and applications in wastewater treatment

Graphene was discovered in 2004 and has attracted intensive interests because of its unique mechanical, electric, thermal, optical, and structural properties, which makes graphene a potential candidate for various applications. Graphene is being used as a composite or filler material with metals, metal oxides, and polymers for potential advanced applications in solar cells, lithium-ion batteries, photocatalysis and sensing. These applications depend upon the distinctive properties of graphene, which in turn depend on the adopted synthetic approach. This article reviews the recent developments in synthesis of graphene and related composite materials. The synthesis of graphene through exfoliation, epitaxial growth and direct growth via carbon source, and modification approaches by covalent and noncovalent methodologies are discussed. Graphene-based metal and metal oxide composites for the purification of wastewater using photolytic process are also presented.     

Identification of irrigation potential areas,using multi-criteria analysis in Khyber District,Pakistan

Environmental Science and Pollution Research - This study explores the opportunities for irrigated agriculture in Khyber District of Former Federally Administered Tribal Area (FATA). Agriculture...     

Modelling categorical data to identify factors influencing concern for the natural environment in Iran

Loglinear modelling techniques were used to identify the interactions and interrelationships underlying categorical environmental concern data collected from 9062 respondents in Iran. After fitting various loglinear models to the data, the most parsimonious model highlighted that a combination of interacting factors, namely educational attainment, age, gender, and residential location were responsible for influencing personal concern for the environment. Although high educational attainment had a close correspondence with high concern for the environment the loglinear results, when visualized with a geographical information system, demonstrated wide spatial variations in educational attainment and concern for the environment. Nearly two-thirds of the respondents were not highly educated, and were therefore not highly concerned for the environment. The finding that both rural and urban male and female respondents in the 15-24 years age category, with 10-12 years of education, had the strongest interaction with personal concern for the environment could be beneficial for policy planners to utilize education as the primary instrument to enhance environmental governance and prospects for sustainable development.     

Short-term in vitro and in vivo genotoxicity testing systems for some water bodies of Northern India

The genotoxicity of certain water bodies was evaluated employing the DNA repair defective mutants of Escherichia coli, induction of prophage lamda in the lysogen and the plasmid nicking assay. All the test DNA repair defective mutants invariably exhibited more sensitivity than their isogenic wild-type strains but distinctive patterns against the three water samples viz. industrial waste water and the groundwater samples obtained from industrial estate of Aligarh as well as river water of Yamuna at Agra. A significant level of phage induction was also recorded in the test system exhibiting maximum induction in case of industrial waste water followed by that in river and groundwater samples, respectively. The single- and double-strand breaks were also observed in the plasmid DNA treated with industrial waste water and the river water samples. These findings are suggestive of the DNA damage induced by the test samples with the probable role of SOS repair in E. coli.