Metal concentrations in water, sediment, and fish from sewage-fed aquaculture ponds of Kolkata, India

The concentrations of lead, cadmium, chromium, copper, and zinc were investigated in the sewage-fed pond water, sediment, and the various organs of Labeo rohita, Catla catla, Cirrhinus mrigala, Oreochromis mossambicus, and Cyprinus carpio cultured in sewage-fed ponds, Kolkata, India. Among the metals, cadmium, lead, and zinc were detected in water and, except lead, were below the water quality guideline levels for the protection of freshwater aquatic life proposed by CEQG (Canadian Environmental Quality Guidelines) and AENV (Alberta Environment). Therefore, lead could pose danger to aquatic organisms. All the five metals were detected in the sediment and, except cadmium and lead, were below the sediment quality guideline levels for aquatic life proposed by EPA (Environmental Protection Agency). Therefore, these two metals could be toxic to aquatic organisms. Significant (P > 0.05) differences were observed among the five fish species for all these metals accumulation. Also, significant (P > 0.05) differences were noticed among these metals accumulation in fish organs. Cadmium showed the least bioaccumulation, while zinc showed the highest bioaccumulation in all the fish species. Though the metal concentration in the different fish tissues was variable, the highest concentration was found in kidney and the lowest in the muscle. Concentrations of these metals in the muscle tissue of all the fish species were well below the consumption safety tolerance in fish set by WHO/FAO, and thus, so far as these metals are concerned, these sewage-fed cultured fishes are safe and suitable for human consumption.     

Characterization of fluoride-tolerant halophilic Bacillus flexus NM25 (HQ875778) isolated from fluoride-affected soil in Birbhum District, West Bengal, India

A new Gram-positive, nonpigmented, rod-shaped fluoride-tolerant bacterial strain, NM25, was isolated from waterlogged muddy field soil collected from the fluoride endemic area of Rampurhat II block (average fluoride in water, 4.7 mg/l, and in soil, 1.5 mg/kg) in Birbhum District, West Bengal, India. The study was undertaken to characterize the fluoride-tolerant bacterial isolate, to determine its role in bioaccumulation of fluoride, and to analyze the water and soil quality of the bacterial environment. The isolate was positive for catalase, lipase, urease, protease, oxidase, and H₂S production, but negative for indole production, nitrate reduction, and Vogues–Proskauer test. The organisms were sensitive to recommended doses of ofloxacin, kanamycin, rifampicin, levofloxacin, vancomycin, gatifloxacin, gentamicin, doxycycline, streptomycin, and nalidixic acid but resistant to ampicillin. Based on the phenotypic characteristics, 16S rRNA gene sequence, and phylogenetic analysis, the bacterial isolate NM25 was identified as Bacillus flexus. The G+C content of the 16S rDNA was 53.14 mol%. This strain tolerated up to 20 % (w/v) NaCl in nutrient agar medium and was grown at the pH range 4–12. It reduced fluoride concentration up to 67.45 % and tolerated more than 1,500 ppm of fluoride in brain–heart infusion agar medium.     

Influence of activated carbon amendment on the accumulation and elimination of PCBs in the earthworm Eisenia fetida

In this study we investigated the use of activated carbon (AC) as a soil amendment for reducing bioavailability of polychlorinated biphenyls (PCBs) to the earthworm Eisenia fetida. Artificial soil was contaminated with PCBs and used in bioaccumulation experiments fresh or after aging for 19 months. PCB bioaccumulation in earthworms was reduced by 68% when AC was placed as a layer without mixing and by 94% when AC was manually mixed into the soil. Aging of the same AC mixed soil for 19 months resulted in an overall reduction of 99% in PCB biouptake. AC-treated aged soil also showed two orders of magnitude lower equilibrium aqueous concentrations of PCBs compared to untreated aged soils. The findings from this study indicate that application of engineered sorbents like AC to PCB impacted soils may greatly reduce PCB uptake at the base of the terrestrial food chain.     

Semi-parametric Bayesian density estimation using ranked set sample in the presence of ranking error

In this paper, we propose a Bayesian method to estimate the underlying density function of a study variable Y using a ranked set sample in which an auxiliary variable X is used to rank the sampling units. The amount of association between X and Y is not known, resulting in an unknown degree of ranking error. We assume that (X, Y) follows a Morgenstern family of distributions. The study variable Y is assumed to have a parametric distribution, with the distribution of the parameters having a Dirichlet process prior. A Markov chain Monte Carlo procedure is developed to obtain a Bayesian estimator of the desired density function as well as of the ranking error. A simulation study is used to evaluate the performance of the proposed method. An example from forestry is used to illustrate a real-life application of the proposed methodology.     

Impact of forest policies on timber production in India: a review

Until the 20th century, forest policies across the globe focused primarily on effective forest utilization for timber production. Subsequent loss of forest land prompted many countries to review and amend such policies, in an attempt to incorporate the principles of conservation and sustainable forest management. One of the countries to implement such changes was India, which introduced new policies, acts and programmes to regulate forest conversion and degradation, beginning in the 1980s. These policies, acts, and programmes included the Forest Conservation Act of 1980, the National Forest Policy of 1988 and the Hon. Supreme Court Order of 1996. All of these regulations affected the timber supply from government forest areas, and created a huge gap in timber supply and demand. Currently, this deficit is met through imports and trees outside forests (TOFs). Timber production from government forest areas is abysmally low (3.35% of total demand) compared to potential timber production from TOFs, which fulfil 45% of the total timber demand in India. This implies that TOFs have immense potential in meeting the growing timber demand; however, they have not been fully utilized due to discrepancies in state level TOFs’ policies. The present paper provides a review of different forest policies, acts and guidelines in relation to timber production in India, and provides specific recommendations in order to maximize timber production in the context of increasing demand for timber products.     

Laccase-catalyzed removal of 2,4-dimethylphenol from synthetic wastewater: effect of polyethylene glycol and dissolved oxygen

The potential use of laccase (SP-504) in an advanced oxidation-based treatment technology to remove 2,4-dimethylphenol (DMP) from water was investigated with and without the additive, polyethylene glycol (PEG). The DMP concentration was varied between 1.0 and 5.0 mM. The optimization of pH and enzyme concentration in the presence and absence of PEG was carried out. All experiments were carried out in continuously stirred reactors for 3h at room temperature. The reaction was initiated by adding enzyme to the reaction mixture. For more than 95% removal of DMP, the presence of PEG reduced the inactivation of enzyme so that the required enzyme concentrations were reduced by about 2-fold compared to the same reactions in the absence of PEG. Finally, the PEG concentrations were optimized to obtain the minimum dose required. For higher substrate concentrations, the availability of oxygen was insufficient in achieving 95% or more removal. Therefore, the effect of increasing dissolved oxygen at higher substrate concentration was investigated. The laccase studied was capable of efficiently removing DMP at very low enzyme concentrations and hence shows great potential for cost-effective industrial applications.     

Sustainability of metal recovery from E-waste

The issue of E-waste disposal is concerning all the stakeholders, from policymakers to the end users which have accelerated the research and development on environmentally sound disposal of E-waste. The recovery of metals (gold, tantalum, copper, iron etc.) from E-waste has become an important focus. The mechanical recycling, thermo-chemical processes like pyrolysis, pyro-, hydro- and biometallurgical processes can play important roles in the Metal Recovery from E-waste (MREW) technology. For the industrial application of the MREW technology, it is important to analyze the sustainability. In this paper, two case studies have been presented on E-waste recycling industries in India and China. Based on the literature data, an attempt has been made to assess qualitatively the overall sustainability of MREW technology considering the three pillars, i.e., environmental, economic and social. Two conceptual frameworks with (Option-2) and without (Option-1) pyrolysis for integrated MREW units have been developed and the generalized energy and environmental impact analysis has been made using the principles of LCA. The impacts of two options have been compared. Option 2 has been found to be more efficient and sustainable. It has been realized that climate change, fossil fuel depletion, water depletion, eutrophication, acidification, fresh and marine water ecotoxicity are possible impact categories. The recommendations based on the generalized assessment are in good agreement with the findings of previous researchers on individual steps of MREW unit. The findings of this paper are expected to be beneficial to researchers and stakeholders for research directions and decision making on MREW.

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Using a relative health indicator (RHI) metric to estimate health risk reductions in drinking water

When a new drinking water regulation is being developed, the USEPA conducts a health risk reduction and cost analysis to, in part, estimate quantifiable and non-quantifiable cost and benefits of the various regulatory alternatives. Numerous methodologies are available for cumulative risk assessment ranging from primarily qualitative to primarily quantitative. This research developed a summary metric of relative cumulative health impacts resulting from drinking water, the relative health indicator (RHI). An intermediate level of quantification and modeling was chosen, one which retains the concept of an aggregated metric of public health impact and hence allows for comparisons to be made across “cups of water,” but avoids the need for development and use of complex models that are beyond the existing state of the science. Using the USEPA Six-Year Review data and available national occurrence surveys of drinking water contaminants, the metric is used to test risk reduction as it pertains to the implementation of the arsenic and uranium maximum contaminant levels and quantify “meaningful” risk reduction. Uranium represented the threshold risk reduction against which national non-compliance risk reduction was compared for arsenic, nitrate, and radium. Arsenic non-compliance is most significant and efforts focused on bringing those non-compliant utilities into compliance with the 10 μg/L maximum contaminant level would meet the threshold for meaningful risk reduction.     

Beryllium Concentrations in Ambient Air and Its Source Identification

Beryllium concentrations in atmospheric particulate and soil samples in and around a Beryllium Processing Facility (BPF) have been measured. The mean air concentration level of beryllium in and around the fence line of the BPF is 0.48 ± 0.43 ng m^-3 (n = 397) and is mostly influenced by diurnaland seasonal changes. The observed air concentration levelswere well below the prescribed ambient air quality (AAQ)standard of 10 ng m^-3. The soil concentration levels ofberyllium in the study area were found to be in the range of 1.42–2.75 g g^-1. The mass median aerodynamic diameter (MMAD)of beryllium aerosols in ambient air was found to be 6.9 m.Source identification using the Enrichment Factor (EF) approachindicates soil as the predominant contributory source for air concentrations at the site.