Biochemical responses,growth and reproduction of earthworm in low density polyethylene (LDPE)

There is an unprecedented production of plastic that is accelerating its disposal while affecting the fitness of the terrestrial as well as the aquatic environment. The term microplastics refers to plastic fragments that are less than 5 mm in size and are widely distributed in the environment. Therefore, the present study intends to explore the biological response of earthworms (Eisenia fetida) toward different concentrations of low-density polyethylene. E. fetida treated with low-density polyethylene concentration (Control), 250 mg kg⁻¹, 1000 mg kg⁻¹, 6000 mg kg⁻¹, 12,000 mg kg^−1, and 25,000 mg kg⁻¹. The above ratios were thoroughly mixed with 1kg of artificial soil and tested for growth, reproduction (cocoons and hatchling count), and enzymatic activities namely superoxide dismutase, guaiacol peroxidase, glutathione-S-transferase, and glutathione reductase and molecular docking studies. No mortality was observed during the exposure period at any concentrations. On the 28th day, when compared to the control the highest decrease in body weight of earthworms was observed in 25,000 mg (28.4%) followed by 12,000 mg (12.2%) and 6000 mg (3.4%). The cocoon and hatchlings significantly declined as the dose of microplastics increases. Enzymatic activity such as SOD and POD showed declined trend as the dose increased, while GST and GR increased with an increase in microplastic concentrations on 28th day. Furthermore, molecular docking showed that LDPE can modulate the activity of all four enzymes significantly.     

Nanotechnology applications in pollution sensing and degradation in agriculture: a review

With the rise in the global population, the demand for increased supply of food has motivated scientists and engineers to design new methods to boost agricultural production. With limited availability of land and water resources, growth in agriculture can be achieved only by increasing productivity through good agronomy and supporting it with an effective use of modern technology. Advanced agronomical methods lay stress not only on boosting agricultural produce through use of more effective fertilizers and pesticides, but also on the hygienic storage of agricultural produce. The detrimental effects of modern agricultural methods on the ecosystem have raised serious concerns amongst environmentalists. The widespread use of persistent pesticides globally over the last six decades has contaminated groundwater and soil, resulting in diseases and hardships in non-target species such as humans and animals. The first step in the removal of disease causing microbes from food products or harmful contaminants from soil and groundwater is the effective detection of these damaging elements. Nanotechnology offers a lot of promise in the area of pollution sensing and prevention, by exploiting novel properties of nanomaterials. Nanotechnology can augment agricultural production and boost food processing industry through applications of these unique properties. Nanosensors are capable of detecting microbes, humidity and toxic pollutants at very minute levels. Organic pesticides and industrial pollutants can be degraded into harmless and often useful components, through a process called photocatalysis using metal oxide semiconductor nanostructures. Nanotechnology is gradually moving out from the experimental into the practical regime and is making its presence felt in agriculture and the food processing industry. Here we review the contributions of nanotechnology to the sensing and degradation of pollutants for improved agricultural production with sustainable environmental protection.     

Characterization of bacterial diversity in an atrazine degrading enrichment culture and degradation of atrazine,cyanuric acid and biuret in industrial wastewater

An enrichment culture was used to study atrazine degradation in mineral salt medium (MSM) (T1), MSM+soil extract (1:1, v/v) (T2) and soil extract (T3). Results suggested that enrichment culture required soil extract to degrade atrazine, as after second sequential transfer only partial atrazine degradation was observed in T1 treatment while atrazine was completely degraded in T2 and T3 treatments even after fourth transfer. Culture independent polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) technique confirmed selective enrichment of genus Bacillus along with Pseudomonas and Burkholderia. Degradation of atrazine/metabolites in the industrial wastewater was studied at different initial concentrations of the contaminants [wastewater-water (v/v) ratio: T1, 1:9; T2, 2:8; T3, 3:7; T4, 5:5 and T5, undiluted effluent]. The initial concentrations of atrazine, cyanuric acid and biuret ranged between 5.32 and 53.92 µg mL^?1, 265.6 and 1805.2 µg mL^?1 and 1.85 and 16.12 µg mL^?1, respectively. The enrichment culture was able to completely degrade atrazine, cyanuric acid and biuret up to T4 treatment, while no appreciable degradation of contaminants was observed in the undiluted effluent (T5). Inability of enrichment culture to degrade atrazine/metabolites might be due to high concentrations of cyanuric acid. Therefore, a separate study on cyanuric acid degradation suggested: (i) no appreciable cyanuric acid degradation with accumulation of an unidentified metabolite in the medium where cyanuric acid was supplemented as the sole source of carbon and nitrogen; (ii) partial cyanuric acid degradation with accumulation of unidentified metabolite in the medium containing additional nitrogen source; and (iii) complete cyanuric acid degradation in the medium supplemented with an additional carbon source. This unidentified metabolite observed during cyanuric acid degradation and also detected in the enrichment culture inoculated wastewater samples, however, was degraded up to T4 treatments and was persistent in the T5 treatment. Probably, accumulation of this metabolite inhibited atrazine/cyanuric acid degradation by the enrichment culture in undiluted wastewater.     

Degradation of atrazine in mineral salts medium and soil using enrichment culture

Atrazine degrading enrichment culture was prepared by its repeated addition to an alluvial soil and its ability to degrade atrazine in mineral salts medium and soil was studied. Enrichment culture utilized atrazine as a sole source of carbon and nitrogen in mineral salts medium and degradation slowed down when sucrose and/or ammonium hydrogen phosphate were supplemented as additional source of carbon and nitrogen, respectively. Biuret was detected as the only metabolite of atrazine while deethylatrazine, deisopropyatrazine, hydroxyatrazine and cyanuric acid were never detected at any stage of degradation. Enrichment culture degraded atrazine in an alkaline alluvial soil while no degradation was observed in the acidic laterite soil. Enrichment culture was able to withstand high concentrations of atrazine (110 μg/g) in the alluvial soil as atrazine was completely degraded. Developed mixed culture has the ability to degrade atrazine and has potential application in decontamination of contaminated water and soil.     

Health cost of salinity contamination in drinking water: evidence from Bangladesh

Environmental Economics and Policy Studies - This study estimates health cost of salinity contamination in drinking water in the severe salinity affected three south-western districts of...     

Two-dimensional modeling of torrefaction of a large biomass particle

A two-dimensional (2-D) model is developed to predict the torrefaction behavior of a large wet biomass particle. Although one-dimensional (1-D) model is found to be adequate for L/D ≥ 6, the necessity of using 2-D model at lower L/D ratios and higher torrefaction temperature is established. Errors up to 18% are observed in predicted mass fractions between 1-D and 2-D models. The center temperatures differed more, up to 96%, between z = 0 and z = L/2 in 2-D model which is not captured by the 1-D model. The model predictions agree well with the experimental results of the present authors and others. The evolution of the temperature profile is found to govern the mass fraction profile. At higher reactor temperature, three distinct zones are visible in the contour plots: peripheral fully torrefied zone, intermediate torrefying zone, and core with unreacted virgin biomass zone. Simulation studies show the formation of two symmetric annular hot spots at the ends, which move inward axially and subsequently merge at the center, the rate being faster for smaller L/D ratio. However, 1-D model does not provide such insight. The effects of reactor temperature, particle size, the residence time, and the initial moisture content on the torrefaction behavior are investigated.     

Overview on recent advances of magnetic metal–organic framework (MMOF) composites in removal of heavy metals from aqueous system

Environmental Science and Pollution Research - Developing a novel, simple, and cost-effective analytical technique with high enrichment capacity and selectivity is crucial for environmental...