Mechanism of Cd（II） adsorption by macrofungus Pleurotus platypus

The mechanism of Cd(II) uptake by the dead biomass of macrofungus Pleurotus platypus was investigated using di erent chemical and instrumental techniques. Sequential removal of cell wall components of the biosorbent revealed that structural polysaccharides play a predominant role in the biosorption of Cd(II). The adsorption kinetics fitted well with the pseudo second-order model suggested that the adsorption of Cd(II) on P. platypus involved a chemisorption process. Transmission electron microscopy of the cadmium exposed biomass confirmed the deposition of the metal mainly in the cell wall. Fourier transform infrared spectroscopic analysis of the metal loaded biosorbent confirmed the participation of –OH, –NH and C–O–C groups in the uptake of Cd(II). Energy dispersive X-ray analysis of the biosorbent before and after metal uptake revealed that the main mechanism of adsorption was ion-exchange. The e ectiveness of CaCl2 in the desorption of cadmium perhaps suggested the exchange of Ca2+ with Cd(II).     

Assessment of Ergonomic and Occupational Health-Related Problems Among Female Prawn Seed Collectors of Sunderbans,West Bengal,India

Abstract

Sixty female prawn seed collectors and 60 female control subjects from Sajenakhali and Sandeshkhali blocks of Sunderbans, West Bengal, India, were randomly selected to evaluate and compare musculoskeletal disorders and physiological stress. The control group was engaged in domestic work involving minimum hand-intensive activities. The modified Nordic musculoskeletal questionnaire and rapid entire body assessment were used. Most subjects suffered from discomfort in different body parts, especially in the lower back (98%), knees (88%), shoulders (75%), ankles (70%) and feet (67%). This study reveals that female prawn seed collectors suffer from significant physiological load and extreme physiological stress due to prolonged working hours in a standing posture and excessive work pressure. Consequently, all these factors affect female prawn seed collectors ‘ health and work performance.     

Transformation of 4-nonylphenol isomers during biosolids composting

4-Nonylphenol, a degradation intermediate of commercial surfactant and known endocrine disruptor, has been frequently detected at levels up to several thousand microgl(-1) in surface waters and up to several hundred mgkg(-1) (dry weight) in soil and sediment samples. Large quantities of 4-NP can be quickly sorbed by the organic rich solid phase during wastewater treatment and are concentrated in biosolids, a possible major source for 4-NP in the environment. Microbial transformation in culture studies followed different mechanisms for different 4-NP isomers, which have different estrogenic activity. Composting is a process of solid matrix transformation where biological activity is enhanced by process control. This approach has been used successfully in remediation of contaminated soils and sludges. In this study, the transformation kinetics of 4-NP and its isomers were characterized during biosolids composting. Five distinctive 4-NP isomer groups with structures relative to alpha- and beta-carbons of the alkyl chain were identified in biosolids. Composting biosolids mixed with wood shaving at a dry weight percentage ratio of 43:57 (C:N ratio of 65:1) removed 80% of the total 4-NP within two weeks. At this biosolids/wood shaving ratio (B:WS), the transformation of total 4-NP and its isomers followed second-order kinetic. Higher B:WS ratios yielded significantly slower 4-NP transformation which followed first-order kinetic. Isomers with alpha-methyl-alpha-propyl structure transformed significantly slower than those with less branched tertiary alpha-carbon and those with secondary alpha-carbon, suggesting isomer-specific degradation of 4-NP during biosolids composting.     

Comparison between availability of heavy metals in dry and wetland tailing of an abandoned copper tailing pond

Wetland sediments are generally considered as a sink for metals and, in the anoxic zone, may contain very high concentrations of heavy metals in reduced state. A comprehensive study was carried out to compare the differences of total, environmentally available (Env-Av), HOAC, EDTA and DTPA available heavy metal fraction in tailing of the marshy area of a copper tailing pond and the dry tailing. The average concentrations of all the seven metals in the wetland tailing were found higher than dry tailing. Regarding pH, organic carbon, availailable N, P and K also found higher in marshy wetland tailing compare to the dry tailing. This information is needed in order to understand wetland system and to assure that wetlands do not themselves eventually become sources of metal contamination to surrounding areas. But as levels of pollutants increases, the ability of a wetland system to incorporate waste can be impaired and the wetland can become a source of toxicity.     

Effect of pendimethalin and quizalofop on N<Subscript>2</Subscript>-fixing bacteria in relation to availability of nitrogen in a <Emphasis Type="Italic">Typic Haplustept</Emphasis> soil of West Bengal,India

An experiment was conducted under laboratory conditions to investigate the effect of two systemic herbicides viz., pendimethalin and quizalofop, at their recommended field rates (1.0 kg and 50 g active ingredient ha^− 1, respectively) on the growth and activities of non-symbiotic N₂-fixing bacteria in relation to mineralization and availability of nitrogen in a Typic Haplustept soil. Both the herbicides, either singly or in a combination, stimulated the growth and activities of N₂-fixing bacteria resulting in higher mineralization and availability of nitrogen in soil. The single application of quizalofop increased the proliferation of aerobic non-symbiotic N₂-fixing bacteria to the highest extent while that of pendimethalin exerted maximum stimulation to their N₂-fixing capacity in soil. Both the herbicides, either alone or in a combination, did not have any significant difference in the stimulation of total nitrogen content and availability of exchangeable NH₄ ⁺ while the solubility of NO₃ ⁻ was highly manifested when the herbicides were applied separately in soil.     

Assessment of chromium efficacy on germination,root elongation,and coleoptile growth of wheat (Triticum aestivum L.) at different growth periods

The tannery effluents contain a high concentration of chromium (Cr). It drastically reduces the crop yield when used for irrigation purpose. A huge volume of tannery effluents is available as irrigation for crop production. It is negatively affecting germination as well as yield of the crop. The wheat seeds were exposed to five different concentrations of Cr (0, 20, 40, 80, and 100 ppm). In Petri plates, 100 seeds were placed and the germination percent was recorded after 72 hour (h). Root elongation and coleoptile growth were measured at 72, 120, 168, and 240 h. Results showed that the germination percent of the test crop decreased with increasing Cr levels. It decreased by 6, 14, 30, and 37 % under the Cr concentration of 20, 40, 80, and 100 ppm, respectively. The root elongation was more sensitive than the coleoptile growth. The negative correlation was found between Cr levels and root elongation as well as coleoptile growth. These growth parameters were significantly affected up to 80 ppm of Cr level. The wheat growers using tannery effluent as irrigation should be well treated prior to application.     

Early-season agricultural drought: detection, assessment and monitoring using Shortwave Angle and Slope Index (SASI) data

Early season or crop-planting-period (ES/CPP) drought conditions have become a recurrent phenomenon in tropical countries like India, due to fluctuations in the time of onset and progression of monsoon rains. ES/CPP agricultural drought assessment is a major challenge because of the difficulties in the generation of operational products on soil moisture at larger scales. The present study analyzed the Shortwave Angle Slope Index (SASI) derived from Near Infrared and Shortwave Infrared data of Moderate Resolution Imaging Spectroradiometer, for tracking surface moisture changes and assessing the agricultural drought conditions during ES/CPP, over Andhra Pradesh state, India. It was found that in-season progression of SASI was well correlated with rainfall and crop planting patterns in different districts of the study area state in both drought and normal years. Rainfall occurrence, increase in crop planted area, and decrease in SASI were in chronological synchronization in the season. Change in SASI from positive to negative values is a unique indication of dryness to wetness shift in the season. Duration of positive SASI values indicated the persistence of agricultural drought in the crop planting period. Mean SASI values were able to discriminate an area which was planted in normal year and unplanted in drought year. SASI thresholds provide an approximate and rapid estimate of the crop planting favorable area in a region which is useful to assess the impact of drought. Thus, SASI is a potential index to strengthen the existing operational drought monitoring systems. Further work needs to be on the integration of multiple parameters—SASI, soil texture, soil depth, rainfall and cropping pattern, to evolve a geospatial product on crop planting favorable areas. Such products pave the way for quantification of drought impact on agriculture in the early part of the season, which is a major inadequacy in the current drought monitoring system.     

Evaluation of heavy metal contaminants in prepared noodles: source allocation and health risk assessment

Environmental Science and Pollution Research - In recent years, special attention has been given to emission research that led to the deposition of toxicants from road traffic. Thus, it is...