Removal of substituted phenols onto iron‐treated Nostoc sp. biomass

This study explored the possibility of removing 4‐nitrophenol (4‐NP) and 2,4‐dichlorophenol (2,4‐DCP) from water by using a dead blue‐green algae, Nostoc sp., dried and untreated and dried and treated with iron (Fe‐treated with 0.1 M ferric chloride solution for 1 day). The Nostoc sp. untreated and Fe‐treated biomass were used to study the sorption and desorption of 4‐NP and 2,4‐DCP. The effects of solute concentration, ionic strength, and temperature on sorption and desorption in the presence of untreated and treated Nostoc sp. biomass were investigated. The Fe‐treated Nostoc sp. biomass sorbed higher amounts of both 4‐NP and 2,4‐DCP than the untreated biomass. The percent cumulative desorption decreased from 6.41% to 0.28% and 1.84% to 0.19%, respectively, for 4‐NP and 2,4‐DCP for the Fe‐treated biomass. Biosorption of 4‐NP and 2,4‐DCP onto untreated and Fe‐treated Nostoc sp. biomass conformed to Freundlich isotherms. Iron treatment of Nostoc sp. biomass increased the value of ln K from 8.07 to 8.59 for 4‐NP and from 8.04 to 8.51 for 2,4‐DCP but decreased their desorption. An increase in ionic strength (0.003–0.03) increased the biosorption of both substituted phenols and decreased their percent desorption. An increase in temperature in the range of 15–35°C decreased the sorption of 4‐NP and 2,4‐DCP onto both untreated and Fe‐treated Nostoc sp. biomass and increased their desorption, indicating that the biosorption of both substituted phenols onto untreated and Fe‐treated Nostoc sp. biomass was principally a physical process. The results of this study suggest that Fe‐treated dried Nostoc sp. biomass could be explored as an inexpensive and eco‐friendly material for the effective removal of these phenols and, potentially, other chemicals from industrial wastewater and contaminated groundwater.     

Agro-potentiality of distillery effluent on soil and agronomical characteristics of Abelmoschus esculentus L. (okra)

The present study showed that irrigation of soil with different effluent concentrations (10, 25, 50, 75, and 100 %) of distillery effluent (DE) for 60 days resulted in significant (P?<?0.001) changes in moisture content; electrical conductivity (EC), pH, chlorides (Cl^?), total organic carbon (TOC), exchangeable sodium (Na⁺), available potassium (K⁺), calcium (Ca²⁺), magnesium (Mg²⁺), iron (Fe²⁺), total Kjeldahl nitrogen (TKN), available phosphorus (P), and sulfate (SO₄ ^2?) of soil. The non-significant (P?>?0.05) changes were observed for water-holding capacity and bulk density of the soil. Among various concentrations of DE irrigation, irrigation with 100 % effluent concentration increased moisture content, (24.85 %), EC (77.88 %), Cl^? (285.95 %), TOC (3,171.42 %), exchangeable Na⁺ (241.04 %), available K⁺ (52.49 %), Ca²⁺ (990.37 %), Mg²⁺ (1,751.72 %), TKN (1,417.00 %), available P (305.00 %), and SO₄ ^2? (75.32 %) in the soil and decreased pH (?20.22 %). The more stimulation in agronomical parameters such as shoot length, root length, number of leaves, flowers, pods, dry weight, fresh weight, chlorophyll content, leaf area index, and crop yield of A. esculentus were observed to be inversely proportional to the concentration of effluent water, with the best results being obtained at a dilution of 25 % of DE concentration.     

Biogeocomposite material and its heavy metal adsorption potential from aqueous solutions

Biosorption process is emerging as a potential alternative for the heavy metal removal from aqueous solutions. A packed bed column containing biomaterials like papaya leaf powder and paddy straw powder was used for copper removal from aqueous solutions. The breakthrough curve was having an S-shaped profile and the breakthrough time became less with increase in initial concentration. Percentage removal of copper was around 85% and 77% for papaya leaf powder and paddy straw powder, respectively for a contact time of 120 minutes and initial concentration of 10 mg/L. A biogeocomposite material was developed to test the enhancement in adsorption using layers of non-woven geotextile material and a significant increase in adsorption was obtained. With the addition of geotextile material in between papaya powder layer and paddy straw powder, there was an average increase of 12.66% and 11.98%, respectively for the removal. A biocomposite material was developed with a mixture of the two biosorbents and the adsorption value of the biocomposite material was in between the two biosorbents. The applicability of Yoon Nelson model and Adam Bohart model were also evaluated and the most suitable model came out to be Yoon and Nelson model.     

Nanosensors and nanobiosensors in food and agriculture

The food and agriculture sector controls the economic growth of a developing country. The food industries have practices of growing crops, raising livestock and sea foods, food processing and packaging, regulating production and distribution with quality and safety. The process control and monitoring quality are crucial steps. Here we review nanosensors and nanobiosensors as alternative of classical quantification methods. Nanoscale dimensions of metal nanoparticles, metal nanoclusters, metal oxide nanoparticles, metal and carbon quantum dots, graphene, carbon nanotubes, and nanocomposites expand the sensitivity by signal amplification and integrate several novel transduction principles such as enhanced electrochemical, optical, Raman, enhanced catalytic activity, and superparamagnetic properties into the nanosensors. The electrochemical nanosensors, optical nanosensors, electronic nose and electronic tongue, nanobarcode technology, and wireless nanosensors have revolutionized the sensing in food and agriculture sectors with multiplex and real-time sensing capabilities. Despite previous success stories of the remunerative health sector, the approaches are transferred subsequently to food and agriculture sector; with potential application in detection of food contaminants such as preservatives, antibiotics, heavy metal ions, toxins, microbial load, and pathogens along with the rapid monitoring of temperature, traceability, humidity, gas, and aroma of the food stuff.     

Health risks from PAHs and potentially toxic elements in street dust of a coal mining area in India

Environmental Geochemistry and Health - Polycyclic aromatic hydrocarbons (PAHs) and potentially toxic elements (PTEs) (Ba, Zn, Pb, Cu, Cr, Ni, As, Co) were determined in the road dusts of a coal...     

Measurements of major ion concentration in settled coarse particles and aerosols at a semiarid rural site in India

Deposition rates and deposition velocities of water-soluble ions (F, Cl, NO3, SO4, NH4, Ca, Mg, Na and K) were measured at a rural site (Gopalpura, Agra). Dry deposition samples were collected throughout the year from December 1995 to August 1997, while the aerosol samples were collected only during the winter season of 1996. Surrogate technique was used to collect the dry deposition samples, while aerosol samples were collected on PTFE membrane filter. Deposition velocities (Vd) of SO4 and NO3 are < or = 0.01 m s(-1) while Ca, Mg, Na, K, NH4, F and Cl exhibit greater than 0.01 m s(-1) Equivalent concentration ratios of K/Na, Ca/Na and Mg/Na conform with the corresponding ratios of local soil, indicating the dominant contribution of local sources. Deposition rates are maximum in winter, followed by summer and monsoon. No significant differences are found in dry deposition rates of all ions or in atmospheric concentrations of soil-derived elements with respect to wind direction. However, in aerosols, concentrations of F, Cl, NO3 and SO4 are higher with winds from southwesterly and westerly directions corresponding to pollution sources located in these directions. Deposition data have been used to calculate the critical load of S and N for soil with respect to Triticum vulgaris. The critical load of actual acidity was found to be 622.4 eq ha(-1) year(-1) within the range of 500-1,000 eq ha(-1) year(-1) as assessed by the RAINS-Asia model for this region. The present load of S and N (77.4 and 86.4 eq ha(-1) year(-1)) was much lower than the critical load of S and N (622.4 and 2,000 eq ha(-1) year(-1)), indicating that at present there is no harmful effect on ecosystem structure and function.     

Resource conservation strategies for rice‐wheat cropping systems on partially reclaimed sodic soils of the Indo‐Gangetic region,and their effects on soil carbon

The Indo‐Gangetic plain is characterized by intensive agriculture, largely by resource‐poor small and marginal farmers. Vast swathes of salt‐affected areas in the region provide both challenges and opportunities to bolster food security and sequester carbon after reclamation. Sustainable management of reclaimed soils via resource conservation strategies, such as residue retention, is key to the prosperity of the farmer, as well as increases the efficiency of expensive initiatives to further reclaim sodic land areas, which currently lay barren. After five years of experimentation on resource conservation strategies for rice‐wheat systems on partially reclaimed sodic soils of the Indo‐Gangetic region, we evaluated changes in different soil carbon pools and crop yield. Out of all resource conservation techniques which were tested, rice‐wheat crop residue addition (30% of total production) was most effective in increasing soil organic carbon (SOC). In rice, without crop residue addition (WCR), soils under zero‐tillage with transplanting, summer ploughing with transplanting and direct seeding with brown manuring showed a significant increase in SOC over the control (puddling in rice, conventional tillage in wheat). In these treatments relatively higher levels of carbon were attained in all aggregate fractions compared to the control. Soil aggregate sizes in meso (0.25‐2.0 mm) and macro (2‐8 mm) ranges increased, whereas micro (< 0.25 mm) fractions decreased in soils under zero‐till practices, both with and without crop residue addition. Direct seeding with brown manuring and zero tillage with transplanting also showed an increase of 135% and 95%, respectively, over the control in microbial biomass carbon, without crop residue incorporation. In zero tillage with transplanting treatment, both with and without crop residue showed significant increase in soil carbon sequestration potential. Though the changes in accrued soil carbon did not bring about significant differences in terms of grain yield, overall synthesis in terms of balance between yield and carbon sequestration indicated that summer ploughing with transplanting and zero tillage with transplanting sequestered significantly higher rates of carbon, yet yielded on par with conventional practices. These could be appropriate alternatives to immediately replace conventional tillage and planting practices for rice‐wheat cropping systems in the sodic soils of the Indo‐Gangetic region.