Runoff and soil loss from steep slopes treated with low cost bioengineering measures

Soil loss and surface runoff patterns were studied in erosion plots developed on manmade steep slopes (60 percent) over three years (1997–2000) in which rainfall ranged from 1338.4 to 1429.2 mm/year. Surface runoff and soil loss was examined under three different rainfall intensity classes. Runoff was mainly controlled by the rainfall distribution pattern on the seasonal scale. The soil loss was influenced by runoff during the first year. Both soil loss and runoff were reduced due to bioengineering measures in the first year irrespective of species planted. In the third year, combined effects of growth of grasses on protected plots, soil compaction and sediment exhaustion was noticed on runoff and soil loss. This was reflected by reduction in the runoff and soil loss from untreated and treated plots. In the high intensity class, reduction in runoff in treated plots was about 50 percent in three years and reduction in soil loss ranged between 94–95 percent in all plots. Physical treatment with brushwood structures was more efficient in erosion control in the low intensity class.     

Ground level ozone concentrations and its association with NOx and meteorological parameters in Kathmandu valley, Nepal

This paper summarizes the results of a yearlong continuous measurements of gaseous pollutants, NO, NO₂, NO_x and O₃ in the ambient air at Kathmandu valley. Measured concentration of the pollutants in study area is a function of time. NO, NO₂ and O₃ peak occurred in succession in presence of sunlight. At the time of maximum O₃ concentration most of the NO_x are utilized. The diurnal cycle of ground level ozone concentrations, revealed mid-day peak with lower nocturnal concentrations and inverse relationship exists between O₃ and NO_x, which are evidences of photochemical O₃ formation. The observed ground level ozone during monsoon is slight lower than the pre-monsoon value. Further, lack of rainfall and higher temperature, solar radiation in the pre-monsoon have given rise to the gradual build up of ozone and it is lowest during winter. Ground level ozone concentrations measured during bandha (general strike) and weekend are 19% and 13% higher than those measured during weekdays. The most effective ozone abatement strategy for Kathmandu Valley may be control of NO_x emissions.     

Microbe-mediated sustainable bio-recovery of gold from low-grade precious solid waste: A microbiological overview

In an era of electronics, recovering the precious metal such as gold from ever increasing piles of electronic-wastes and metal-ion infested soil has become one of the prime concerns for researchers worldwide. Biological mining is an attractive, economical and non-hazardous to recover gold from the low-grade auriferous ore containing waste or soil. This review represents the recent major biological gold retrieval methods used to bio-mine gold. The biomining methods discussed in this review include, bioleaching, bio-oxidation, bio-precipitation, bio-flotation, bio-flocculation, bio-sorption, bio-reduction, bio-electrometallurgical technologies and bioaccumulation. The mechanism of gold biorecovery by microbes is explained in detail to explore its intracellular mechanistic, which help it withstand high concentrations of gold without causing any fatal consequences. Major challenges and future opportunities associated with each method and how they will dictate the fate of gold bio-metallurgy from metal wastes or metal infested soil bioremediation in the coming future are also discussed. With the help of concurrent advancements in high-throughput technologies, the gold bio-exploratory methods will speed up our ways to ensure maximum gold retrieval out of such low-grade ores containing sources, while keeping the gold mining clean and more sustainable.     

Disinfection of wastewater: comparative evaluation of chlorination and DHS-biotower

The present study reports the onsite evaluation of two pilot scale disinfection units. One of the pilot plants is based on chlorination, and other is based on fixed film aerobic process (biotower). Evaluation study consisted of onsite monitoring of COD, BOD5 and TSS and fecal coliform over a period of three months. Samples were collected from the inlet and outlet of the pilot plants. These pilot plants were evaluated so as to have an appropriate disinfection technology for the treatment of the effluents from upflow anaerobic sludge blanket reactor (UASBR) based sewage treatment plants which could meet the biological quality standards. All the influents samples collected from both the pilot plants contained fecal coliform ranging from 105 to 10(6) MPN/100 ml. The results show that the fecal coliform removal is up to 98.2% and 100% forbiotower and chlorination, respectively. Both, the chlorination and down hanging sponge-biotower (DHS-biotower) improved the quality of effluent from the UASBRin terms of COD, BOD5 and TSS. Though chlorination performed better compared to the DHS-biotower, however, it has additional risk associated with the formation of trihalomethanes (THMs).     

Green Synthesis of Silver Nanoparticle Capped with <Emphasis Type="Italic">Allium cepa</Emphasis> and Their Catalytic Reduction of Textile Dyes: An Ecofriendly Approach

Today, environment pollution control is a matter of concern, everybody is willing to make a product that should be ecofriendly. Nowadays, water resources are full of untreated waste materials, discharge of hazardous and toxic dyes coming from textile and other chemical industries. These environmental hazards are difficult to remove by commercial water treatment plans, thus we need something that would present an efficient means for removal of these hazards. In this research paper, we have synthesize silver nanoparticle in a green way by using aqueous extract of Allium cepa (onion), and further these silver nanoparticle were tested for the catalytic degradation of various dyes by UV/Visible spectroscopy and silver nanoparticle showed reduction in dyes intensity after a particular period of incubation time. SEM and TEM, Particle size and Zeta potential analysis was done to analyze the surface morphology, particle size range and stability of the silver nanoparticle. Greenly synthesized silver nanoparticle was found to be spherical in shape, having particle size value ranged from 50 to 100 nm with a zeta potential value of ?29 mV. An EDX spectroscopy method was used to confirm the presence of silver nanoparticle in the synthesized material. An X-ray crystallography was done to ensure the crystallinity of the silver nanoparticle. Further an ATR-FTIR was performed to confirm the capping of the silver nanoparticle with the phenolic group of the onion. All these study emphasized that silver nanoparticle capped with onion (AgNPs@Ac) is the excellent catalyst for the reduction of hazardous and toxic dyes as well as they serve best purpose of the eco-friendly approach.     

Distribution and correlation of radon and uranium and associated hydrogeochemical processes in alluvial aquifers of northwest India

Environmental Science and Pollution Research - The spatial and vertical distributions of radon and uranium are evaluated in relation to the hydrogeology, geomorphology, and hydrochemistry of...     

Removal of Cr(VI) onto Ficus carica biosorbent from water

The utilization of sustainable and biodegradable lignocellulosic fiber to detoxify the noxious Cr(VI) from wastewater is considered a versatile approach to clean up a contaminated aquatic environment. The aim of the present research is to assess the proficiency and mechanism of biosorption on Ficus carica bast fiber via isotherm models (Langmuir, Freundlich, Temkin, Harkin’s–Jura, and Dubinin–Radushkevich), kinetic models, and thermodynamic parameters. The biomass extracted from fig plant was characterized by scanning electron microscopy and Fourier-transform infrared spectroscopy. To optimize the maximum removal efficiency, different parameters like effect of initial concentration, effect of temperature, pH, and contact time were studied by batch method. The equilibrium data were best represented by the Langmuir isotherm model, and the maximum adsorption capacity of Cr(VI) onto biosorbent was found to be 19.68 mg/g. The pseudo-second-order kinetic model adequately described the kinetic data. The calculated values of thermodynamic parameters such as enthalpy change (?H ⁰), entropy change (?S ⁰), and free energy change (?G ⁰) were 21.55 kJ/mol, 76.24 J/mol?K, and ?1.55 kJ/mol, respectively, at 30 °C which accounted for spontaneous and endothermic processes. The study of adsorbent capacity for Cr(VI) removal in the presence of Na⁺, Mg²⁺, Ca²⁺, SO ₄ ^2? , HCO ₃ ^? and Cl^? illustrated that the removal of Cr(VI) increased in the presence of HCO^3? ions; the presence of Na⁺, SO ₄ ^2? or Cl^? showed no significant influence on Cr(VI) adsorption, while Ca²⁺ and Mg²⁺ ions led to an insignificant decrease in Cr(VI) adsorption. Further, the desorption studies illustrated that 31.10 % of metal ions can be removed from an aqueous system, out of which 26.63 % of metal ions can be recovered by desorption in first cycle and the adsorbent can be reused. The results of the scale-up study show that the ecofriendly detoxification of Cr(VI) from aqueous systems was technologically feasible.     

Semen quality of environmentally exposed human population: the toxicological consequence

Human data on the relationship of semen quality with pesticide and metals are mostly inconsistent. The purpose of the study is to confirm the toxicity of organochlorine pesticide β- and γ-hexachlorocyclohexane (HCH), DDE and DDD, and metals lead or cadmium on sperm motility in epidemiological study among fertile and infertile men and to determine whether in vivo and in vitro results are in the same direction. Semen analysis and estimation of the toxicants were done in 60 fertile and 150 infertile men. In the in vitro studies, sperm were exposed to the highest levels of these toxicants found in vivo, as well as five and ten times higher, and to the mixture of all compounds. The study assesses sperm viability and motility for a period ranging between 30 min and 96 h. Epidemiological data showed an inverse correlation of toxicant with sperm motility. In vitro study showed that γ-HCH and lead after 12 h, cadmium after 8 h, and coexposure to toxicants after 6 h of exposure caused significant concentration- and duration-dependent decline in sperm motility. Data of in vitro study were concurrent with epidemiological finding that might be useful in establishing the possible association between exposure and effect of these selected pollutants on sperm motility.     

Cheaper Fuel and Higher Health Costs Among the Poor in Rural Nepal

Biomass fuels are used by the majority of resource poor households in low-income countries. Though biomass fuels, such as dung-briquette and firewood are apparently cheaper than the modern fuels indoor pollution from burning biomass fuels incurs high health costs. But, the health costs of these conventional fuels, mostly being indirect, are poorly understood. To address this gap, this study develops probit regression models using survey data generated through interviews from households using either dung-briquette or biogas as the primary source of fuel for cooking. The study investigates factors affecting the use of dung-briquette, assesses its impact on human health, and estimates the associated household health costs. Analysis suggests significant effects of dung-briquette on asthma and eye diseases. Despite of the perception of it being a cheap fuel, the annual health cost per household due to burning dung-briquette (US16.94) is 61.3 (US 16.94) is 61.3% higher than the annual cost of biogas (US 10.38), an alternative cleaner fuel for rural households. For reducing the use of dung-briquette and its indirect health costs, the study recommends three interventions: (1) educate women and aboriginal people, in particular, and make them aware of the benefits of switching to biogas; (2) facilitate tree planting in communal as well as private lands; and (3) create rural employment and income generation opportunities.     

Identification of organic phosphorus compounds in the Bronx River bed sediments by phosphorus-31 nuclear magnetic resonance spectroscopy

The European Water Framework Directive 2000/60/EC aims to achieve a good ecological status of all surface water bodies in Europe. The definition of the ecological status is based on the hydromorphological, hydrochemical, and hydrobiological features of water bodies. Numerous methods are applied for the purpose of hydromorphological status assessment. This study attempts to compare four different methods (EcoRivHab, LAWA Field and Overview Survey, and Rapid Bioassessment Protocol) that were applied at two study areas in the Czech part of the Elbe River Basin. The selected catchments represent areas with different sizes and physical geographic as well as socioeconomic characteristics. All the methods applied showed the capacity to identify the natural and even the completely changed reaches and provided good information on the river physical habitat state. However, they are varied from the viewpoint of the number of parameters, number of monitored zones, time and knowledge demands of the performed assessment.