A Cr(VI)-reducing Microbacterium sp. strain SUCR140 enhances growth and yield of Zea mays in Cr(VI) amended soil through reduced chromium toxicity and improves colonization of arbuscular mycorrhizal fungi

Pot culture experiments were conducted in a glasshouse to evaluate the effects of four efficient Cr(VI)-reducing bacterial strains (SUCR44, SUCR140, SUCR186, and SUCR188) isolated from rhizospheric soil, and four arbuscular mycorrhizal fungi (AMF—Glomus mosseae, G. aggregatum, G. fasciculatum, and G. intraradices) alone or in combination, on Zea mays in artificially Cr(VI)-amended soil. Presence of a strain of Microbacterium sp. SUCR140 reduced the chromate toxicity resulting in improved growth and yields of plants compared to control. The bioavailability of Cr(VI) in soil and its uptake by the plant reduced significantly in SUCR140-treated plants; the effects of AMF, however, either alone or in presence of SUCR140 were not significant. On the other hand, presence of AMF significantly restricted the transport of chromium from root to the aerial parts of plants. The populations of AMF chlamydospores in soil and its root colonization improved in presence of SUCR140. This study demonstrates the usefulness of an efficient Cr(VI)-reducing bacterial strain SUCR140 in improving yields probably through reducing toxicity to plants by lowering bioavailability and uptake of Cr(VI) and improving nutrient availability through increased mycorrhizal colonization which also restricted the transport of chromium to the aerial parts.     

Environment polluting conventional chemical control compared to an environmentally friendly IPM approach for control of diamondback moth, <Emphasis Type="Italic">Plutella xylostella</Emphasis> (L.), in China: a review

The diamondback moth, Plutella xylostella, is recognized as a widely distributed destructive insect pest of Brassica worldwide. The management of this pest is a serious issue, and an estimated annual cost of its management has reached approximately US$4 billion. Despite the fact that chemicals are a serious threat to the environment, lots of chemicals are applied for controlling various insect pests especially P. xylostella. An overreliance on chemical control has not only led to the evolution of resistance to insecticides and to a reduction of natural enemies but also has polluted various components of water, air, and soil ecosystem. In the present scenario, there is a need to implement an environmentally friendly integrated pest management (IPM) approach with new management tactics (microbial control, biological control, cultural control, mating disruption, insecticide rotation strategies, and plant resistance) for an alternative to chemical control. The IPM approach is not only economically beneficial but also reduces the environmental and health risks. The present review synthesizes published information on the insecticide resistance against P. xylostella and emphasizes on adopting an alternative environmentally friendly IPM approach for controlling P. xylostella in China.     

Porous material based on modified carbon and the effect of pore size distribution on the adsorption of methylene blue dye from an aqueous solution

Environmental Science and Pollution Research - Carbon porous materials obtained through KOH activation of a furfural?+?hydroquinone?+?urotropine mixture were applied as...     

Impact of riverbank filtration on treatment of polluted river water

The impact of riverbank filtration (RBF) on the treatment of water from the River Yamuna at Mathura, which has disagreeable visual properties, has been investigated. The dissolved organic carbon (DOC) and colour of the river water were 4.0–6.8 mg/L and 40–65 colour units (CU), respectively. Pre-chlorination is in practice to improve raw water quality. Chlorine doses as high as 60 mg/L ahead of the water treatment units reduced colour by about 78%. Removal of DOC and UV-absorbance was less than 18%. In comparison to direct pumping of the river water, collection of water through RBF resulted in the reduction of DOC, colour, UV-absorbance and fecal coliforms by around 50%. However, riverbank filtrate did not conform to the drinking water quality standards. Therefore, riverbank-filtered water along with the Yamuna water were ozonated for different durations. To reduce DOC to the desired level, the dose of ozone required for the riverbank filtrate was found to be considerably less than the ozone required for the river water. RBF as compared to direct pumping of Yamuna water appears to be effective in improving the quality of the raw water.     

Leaching of copper and zinc from spent antifouling paint particles

Leaching of Cu and Zn from a composite of spent antifouling paint particles, containing about 300 mg g⁻¹ and 110 mg g⁻¹ of the respective metals, was studied in batch experiments. For a given set of simulated environmental conditions, release of Cu was independent of paint particle concentration due to attainment of pseudo-saturation, but Zn was less constrained by solubility effects and release increased with increasing particle concentration. Leaching of Cu increased but Zn decreased with increasing salinity, consistent with mechanisms governing the dissolution of Cu₂O in the presence of chloride and Zn acrylates in the presence of seawater cations. Because of complex reaction kinetics and the presence of calcium carbonate in the paint matrix, metal leaching appeared to be greater at 4 °C than 19 °C under many conditions. These findings have important environmental and biological implications regarding the deliberate or inadvertent disposal of antifouling paint residues.     

Development of controlled release nanoformulations of carbendazim employing amphiphilic polymers and their bioefficacy evaluation against Rhizoctonia solani

Controlled release nanoformulations of carbendazim (Methyl 1H-benzimidazol-2-ylcarbamate), a systemic fungicide, have been prepared using laboratory synthesized poly(ethylene glycols) (PEGs)-based functionalized amphiphilic copolymers. The release kinetics of carbendazim from developed controlled release (CR) formulations was studied and compared with that of the commercially available 50% Wettable Powder (WP). Further, the bioefficacy evaluation of developed formulations was done against plant pathogenic fungi Rhizoctonia solani by the poison food technique method. The release of maximum amount of carbendazim from developed formulations was dependent on the molecular weight of PEGs and was found to increase with increasing molecular weights. The range of carbendazim release was found to be between 10th to 35th day as compared to commercial formulation which was up to 7th day. The diffusion exponent (n value) of carbendazim in water ranged from 0.37 to 0.52 in the tested formulations. The half-release (t_1/2) values ranged between 9.47 and 24.20 days, and the period of optimum availability (POA) of carbendazim ranged from 9.15 to 26.63 days. Also, ED₅₀ values of the developed formulations vary from 0.40 to 0.74 mg L^?1. These formulations can be used to optimize the release of carbendazim to achieve disease control for the desired period depending on the matrix of the polymer used.     

Distribution,Sources and Sinks of Atmospheric Halogenated Compounds

Based on two comprehensive field studies conducted in California, background concentration (parts per trillion) of N₂O (296.0 X 10³), SF₆ (0.16), CCI₂F₂ (180.8), CCI₃F (103.8), CCI₂FCCIF₂ (16.3), CCI₄ (114.2), CH₃CI (952.9), CHCI3 (23.4), CH₃I (2.4), CH3CCI3 (84.0), CCI₂CCI₂ (43.1), CHCICCI2 (14.5) and CH₃Br (—) have been reported. These trace constituents were identified using retention data on eight GC columns, their electron attachment properties, and their EC thermal response. All but CHCICCI₂ and CH₃Br were measurable 100% of the time at both sites. Cryogenic procedures for SF₆ ambient measurement were developed and successfully used. By an analysis of worldwide emissions of these trace constituents, their ambient levels, and their atmospheric lifetimes, it was possible to determine their origin (natural or anthropogenic). Our results indicate that 27% of organic chlorine contribution to the troposphere comes from fluorocarbons as opposed to a 73% contribution from the chloro-carbons. Further, the anthropogenic organic content in the troposphere was found to be about twice the natural content. Very high CHCI3 concentrations in onshore ocean waters were measured. Ambient data supporting the anthropogenic origin of CCI₄ have been presented.     

Arsenite tolerance in rice (Oryza sativa L.) involves coordinated role of metabolic pathways of thiols and amino acids

Thiolic ligands and several amino acids (AAs) are known to build up in plants against heavy metal stress. In the present study, alteration of various AAs in rice and its synchronized role with thiolic ligand was explored for arsenic (As) tolerance and detoxification. To understand the mechanism of As tolerance and stress response, rice seedlings of one tolerant (Triguna) and one sensitive (IET-4786) cultivar were exposed to arsenite (0–25 μM) for 7 days for various biochemical analyses using spectrophotometer, HPLC and ICPMS. Tolerant and sensitive cultivars respond differentially in terms of thiol metabolism, essential amino acids (EEAs) and nonessential amino acids (NEEAs) vis-á-vis As accumulation. Thiol biosynthesis-related enzymes were positively correlated to As accumulation in Triguna. Conversely, these enzymes, cysteine content and GSH/GSSG ratio declined significantly in IET-4786 upon As exposure. The level of identified phytochelatin (PC) species (PC₂, PC₃ and PC₄) and phytochelatin synthase activity were also more pronounced in Triguna than IET-4786. Nearly all EAAs were negatively affected by As-induced oxidative stress (except phenylalanine in Triguna), but more significantly in IET-4786 than Triguna. However, most of the stress-responsive NEAAs like glutamic acid, histidine, alanine, glycine, tyrosine, cysteine and proline were enhanced more prominently in Triguna than IET-4786 upon As exposure. The study suggests that IET-4786 appears sensitive to As due to reduction of AAs and thiol metabolic pathway. However, a coordinated response of thiolic ligands and stress-responsive AAs seems to play role for As tolerance in Triguna to achieve the effective complexation of As by PCs.     

Phototransformation of herbicide metsulfuron methyl

Phototransformation of the herbicide metsulfuron methyl was investigated on glass surface under sunlight and ultraviolet (UV) light and compared with dark condition. The half-lives of metsulfuron methyl under UV light and sunlight were found to be 0.5 and 7.8 days respectively. Rate of phototransformation followed first order kinetics with significant correlation coefficient. The major photoproducts were identified as methyl-2-sulfonyl-amino-benzoate, 2-amino-6-methoxy-4-methyltriazine and saccharin (O-sulfobenzoimide). Various metabolites from this study were identified by high performance liquid chromatography (HPLC). Authentic samples required for HPLC comparison were prepared in laboratory and characterized on the basis of nuclear magnetic resonance (NMR) and infra red (IR) spectral data. These metabolites were also identified from metsulfuron methyl treated wheat field soil.     

Top-down and bottom-up inventory approach for above ground forest biomass and carbon monitoring in REDD framework using multi-resolution satellite data

This study deals with the future scope of REDD (Reduced Emissions from Deforestation and forest Degradation) and REDD+ regimes for measuring and monitoring the current state and dynamics of carbon stocks over time with integrated geospatial and field-based biomass inventory approach. Multi-temporal and multi-resolution geospatial synergic approach incorporating satellite sensors from moderate to high resolution with stratified random sampling design is used. The inventory process involves a continuous forest inventory to facilitate the quantification of possible CO₂ reductions over time using statistical up-scaling procedures on various levels. The combined approach was applied on a regional scale taking Himachal Pradesh (India), as a case study, with a hierarchy of forest strata representing the forest structure found in India. Biophysical modeling implemented revealed power regression model as the best fit (R ²?=?0.82) to model the relationship between Normalized Difference Vegetation Index and biomass which was further implemented to calculate multi-temporal above ground biomass and carbon sequestration. The calculated value of net carbon sequestered by the forests totaled to 11.52 million tons (Mt) over the period of 20 years at the rate of 0.58 Mt per year since 1990 while CO₂ equivalent reduced from the environment by the forests under study during 20 years comes to 42.26 Mt in the study area.