Methane and nitrous oxide emissions from an integrated rainfed rice–fish farming system of Eastern India

Integration of fish stocking with rice (Oryza sativa L.) cultivation promises an ecologically sound and environmentally viable management of flooded ecosystem. Rice agriculture contributes to the emission of greenhouse gases CH₄ and N₂O, but little is known on the effect of fish rearing in fields planted to rice on the emission of these two greenhouse gases. In a field study, CH₄ and N₂O fluxes were measured from a sub-humid tropical rice field of Cuttack, eastern India, as affected by integrated rice–fish farming under rainfed lowland conditions. Three Indian major carps, Catla catla H., Labeo rohita H. and Cirrhinus mrigala H., and Puntius gonionotus B. were stocked in rice fields planted to two rice cultivars in a split-plot design with no fish and fish as the main treatments and two rice varieties as sub-treatments with three replicates each. Fish rearing increased CH₄ emission from field plots planted to both the rice cultivars with 112% increase in CH₄ emission in cv. Varshadhan and 74% in case of cv. Durga. On the contrary, fish stocking reduced N₂O emission from field plots planted to both the rice varieties. Movement of fish and associated bioturbation coupled with higher dissolved organic-C and CH₄ contents, and lower dissolved oxygen could be the reasons for release of larger quantities of CH₄ from rice + fish plots, while higher dissolved oxygen content might have influenced release of more N₂O from the rice alone treatment. The total greenhouse gas emission, expressed as CO₂ equivalent global warming potential (GWP), was considerably higher from rice + fish plots with CH₄ contributing a larger share (91%) as compared to rice alone plots (78–81%). On the contrary, N₂O had a comparatively lesser contribution with 19–22% share in rice alone plots that was further reduced to 9% in rice + fish plots. However, considering the profit-loss analysis based on the market price of the produce, rice–fish system provided a net profit of $453.36 ha^?1 over rice alone system in spite of higher carbon credit compliance of a rice–fish ecosystem due to larger cumulative GWP.     

Assessment of noise level in Burdwan town, West Bengal

Cities and towns of the world are now facing enormous rise of noise pollution problem due to very high population rise, transport congestion and associated commercial and industrial activities. Burdwan, a district headquarter (100 km away from Kolkata) is one such town where noise pollution is very frequent. In order to assess noise level, noise data were collected from various places of the town by sound level meter with a duration of 30 minutes/location during specified time like 6.00 am, 10.00 am, 1.00 pm, 4.00 pm and 6.00 pm. Most of the monitoring places either belongs to silence category or commercial category areas. From the tabulated data, it was found that sound level lies within the range of 64-85 dB or above in different time at different places. The locations that belong to the silence zone have the noise level up to 90 dB. Statistically noise level in all these zones differ significantly at their peak hours. Noise pollution adversely affects our environment as well as human beings. Sound causes both pathological and psychological disorders in human beings. Implementation of rules and regulations under section 20, 21J, 41, 68(I), 70, 90, 111A of Environment Protection Act, 1986 and of course various technological methods and public awareness are very essential to check noise pollution in Burdwan town.     

Aluminum-based drinking-water treatment residuals: a novel sorbent for perchlorate removal

Perchlorate contamination of aquifers and drinking-water supplies has led to stringent regulations in several states to reduce perchlorate concentrations in water at acceptable levels for human consumption. Several perchlorate treatment technologies exist, but there is significant cost associated with their use, and the majority of them are unable to degrade perchlorate to innocuous chloride. We propose the use of a novel sorbent for perchlorate, i.e. an aluminum-based drinking-water treatment residual (Al-WTR), which is a by-product of the drinking-water treatment process. Perchlorate sorption isotherms (23+/-1 degrees C) showed that the greatest amount (65%) of perchlorate removed by the Al-WTR was observed with the lowest initial perchlorate load (10 mg L(-1)) after only 2 h of contact time. Increasing the contact time to 24 h, perchlorate removal increased from 65 to 76%. A significant correlation was observed between the amounts of perchlorate removed with evolved chloride in solution, suggesting degradation of perchlorate to chloride.     

Mesoporous carbon nanospheres derived from agro-waste as novel antimicrobial agents against gram-negative bacteria

Environmental Science and Pollution Research - Porous carbon nanospheres were synthesized from agro-waste garlic peels by a one-pot facile and easy to scale-up pyrolysis method. Surface morphology...     

Nanoparticles influence on expression of cell cycle related genes in Drosophila: a microarray-based toxicogenomics study

Relatively little is known regarding the interaction of nanoscale objects with dynamic complex biological systems. Microarray-based toxicogenomics studies may serve as a suitable technique to explore the genome wide effects of nanoparticles on any organism through a single experiment. The influence of nanoporous aluminosilicate nanoparticles (NP), citrate-capped gold NP, lipophilic silica NP, BSA-capped silver NP, and lipophilic zinc oxide NP were studied on 75 cell cycle-related genes of adult Drosophila melanogaster. Microarray experiments were conducted after the flies were fed with NP-mixed media for 15 days. Data showed that silver, zinc oxide, and alumino silicate NP predominantly perturbed cell cycle genes, whereas gold and silica NP exerted the least influence on these genes.     

Screening of wheat varieties and associated bacterial population in old alluvial soil of Burdwan, West Bengal

In order to screen out the best variety of wheat (Triticum aestivum) out of eight varieties (viz., HP 1633, BW 11, NW 1014, Sonalika, HUW 468, K 9107, HP 1731 and HUW 234), a field experiment was conducted (from Dec. 2002 to April 2003) in a randomized block design replicated thrice at Crop Research and Seed Multiplication Farm, Burdwan University, West Bengal, India. Various morpho physiological parameters viz., plant population, length of shoot and root, leaf area index (LAI), crop growth rate (CGR), leaf area ratio (LAR), leaf area duration (LAD), net assimilation rate (NAR), yield attributes viz., length of panicles, number of grains per panicle, grain yield, straw yield, pigment content in flag leaf (chlorophyll a, b and total chlorophyll and carotenoid content) were estimated and analyzed statistically Soil bacterial populations were also estimated in the fallow land before sowing of seeds and after harvesting of crop. The HUW 468 variety records higher grain yield, maximum panicle length and maximum chlorophyll b and total chlorophyll content.     

Antimony sorption at gibbsite-water interface

Antimony (Sb) is extensively used in flame retardants, lead-acid batteries, solder, cable coverings, ammunition, fireworks, ceramic and porcelain glazes and semiconductors. However, the geochemical fate of antimony (Sb) remained largely unexplored. Among the different Sb species, Sb (V) is the dominant form in the soil environment in a very wide redox range. Although earlier studies have examined the fate of Sb in the presence of iron oxides such as goethite and hematite, few studies till date reported the interaction of Sb (V) with gibbsite, a common soil Al-oxide mineral. The objective of this study was to understand the sorption behavior of Sb (V) on gibbsite as a function of various solution properties such as pH, ionic strength (I), and initial Sb concentrations, and to interpret the sorption-edge data using a surface complexation model. A batch sorption study with 20 g L⁻¹ gibbsite was conducted using initial Sb concentrations range of 2.03-16.43 μM, pH values between 2 and 10, and ionic strengths (I) between 0.001 and 0.1 M. The results suggest that Sb (V) sorbs strongly to the gibbsite surface, possibly via inner-sphere type mechanism with the formation of a binuclear monodentate surface complex. Weak I effect was noticed in sorption-edge data or in the isotherm data at a low surface coverage. Sorption of Sb (V) on gibbsite was highest in the pH range of 2-4, and negligible at pH 10. Our results suggest that gibbsite will likely play an important role in immobilizing Sb (V) in the soil environment.     

Arsenic immobilization in soils amended with drinking-water treatment residuals

Use of Fe/Al hydroxide-containing materials to remediate As-contaminated sites is based on the general notion that As adsorption in soils is primarily controlled by Fe/Al (hydr)oxides. A low-cost and potentially effective substitute for natural Fe/Al hydroxides could be the drinking-water treatment residuals (WTRs). Earlier work in our laboratory has shown that WTRs are effective sorbents for As in water. We hypothesized that land-applied WTRs would work equally well for As-contaminated soils. Results showed that WTRs significantly (p<0.001) increased the soil As sorption capacity. All WTR loads (2.5, 5, and 10%) significantly (p<0.001) increased the overall amount of As sorbed by both soils when compared with that of the unamended controls. The amount of As desorbed with phosphate (7500 mg kg(-1) load) was approximately 50%. The WTR effectiveness in increasing soil As sorption capacities was unaffected by differences in both soils' chemical properties.     

Active carbon-pools in rhizosphere of wheat (Triticum aestivum L.) grown under elevated atmospheric carbon dioxide concentration in a Typic Haplustept in sub-tropical India

Study on active and labile carbon-pools can serve as a clue for soil organic carbon dynamics on exposure to elevated level of CO2. Therefore, an experimental study was conducted in a Typic Haplustept in sub-tropical semi-arid India with wheat grown in open top chambers at ambient (370 micromol mol-1) and elevated (600 micromol mol-1) concentrations of atmospheric CO2. Elevated atmospheric CO2 caused increase in yield and carbon uptake by all plant parts, and their preferential partitioning to root. Increases in fresh root weight, volume and length have also been observed. Relative contribution of medium-sized root to total root length increased at the expense of very fine roots at elevated CO2 level. All active carbon-fractions gained due to elevated atmospheric CO2 concentration, and the order followed their relative labilities. All the C-pools have recorded a significant increase over initial status, and are expected to impart short-to-medium-term effect on soil carbon sequestration.     

Controlling the fate of roxarsone and inorganic arsenic in poultry litter

A growing body of literature reports 3-nitro-4-hydroxyphenylarsonic acid (roxarsone) degradation in poultry litter (PL) to the more toxic inorganic arsenic (As). Aluminum-based drinking-water treatment residuals (WTR) present a low-cost amendment technology to reduce As availability in PL, similar to the use of alum to reduce phosphorus availability. Batch experiments investigated the effectiveness of WTR in removing roxarsone and inorganic As species from PL aqueous suspensions. Incubation experiments with WTR-amended PL evaluated the effects of WTR application rates (2.5-15% by weight) and incubation time (up to 32 d) at two incubation temperatures (23 and 35 degrees C) on As availability in PL. Batch PL aqueous experiments showed the high affinity of As(V), As(III), dimethylarsinic acid (DMA), monomethylarsonic acid (MMA), and roxarsone for the WTR. The 10% WTR amendment rate decreased As availability in PL by half of that of the unamended (no WTR) PL-incubated samples. The reduction in dissolved As concentrations during incubation of WTR-amended PL samples was kinetically limited, being complete within 13 d. Parallel reductions in roxarsone, As(V), and DMA concentrations were observed with liquid chromatography-inductively coupled plasma mass spectrometry, whereas As(III) and MMA concentrations were always <5% of dissolved As. Incubation temperature did not significantly (p > 0.05) influence dissolved As concentrations in the WTR-amended PL. Potential formation of a copper-containing roxarsone metabolite was considered in PL aqueous suspensions with the aid of electrospray mass spectrometry. Further experiments in the field are necessary to ensure that sorbed As is stable in WTR-amended PL.