Arsenic Contamination in Food-chain: Transfer of Arsenic into Food Materials through Groundwater Irrigation

Arsenic contamination in groundwater in Bangladesh has become an additional concern vis-à-vis its use for irrigation purposes. Even if arsenic-safe drinking-water is assured, the question of irrigating soils with arsenic-laden groundwater will continue for years to come. Immediate attention should be given to assess the possibility of accumulating arsenic in soils through irrigation-water and its subsequent entry into the food-chain through various food crops and fodders. With this possibility in mind, arsenic content of 2,500 water, soil and vegetable samples from arsenic-affected and arsenic-unaffected areas were analyzed during 1999–2004. Other sources of foods and fodders were also analyzed. Irrigating a rice field with groundwater containing 0.55 mg/L of arsenic with a water requirement of 1,000 mm results in an estimated addition of 5.5 kg of arsenic per ha per annum. Concentration of arsenic as high as 80 mg per kg of soil was found in an area receiving arsenic-contaminated irrigation. A comparison of results from affected and unaffected areas revealed that some commonly-grown vegetables, which would usually be suitable as good sources of nourishment, accumulate substantially-elevated amounts of arsenic. For example, more than 150 mg/kg of arsenic has been found to be accumulated in arum (kochu) vegetable. Implications of arsenic ingested in vegetables and other food materials are discussed in the paper

Green-house gas mitigation capacity of a small scale rural biogas plant calculations for Bangladesh through a general Life Cycle Assessment approach

Calculations towards determining the greenhouse gas mitigation capacity of a small-scale biogas plant (3.2 m3 plant) using cow dung in Bangladesh are presented. A general life cycle assessment was used, evaluating key parameters (biogas, methane, construction materials and feedstock demands) to determine the net environmental impact. The global warming potential saving through the use of biogas as a cooking fuel is reduced from 0.40 kg CO2 equivalent to 0.064 kg CO2 equivalent per kilogram of dung. Biomethane used for cooking can contribute towards mitigation of global warming. Prior to utilisation of the global warming potential of methane (from 3.2 m3 biogas plant), the global warming potential is 13 t of carbon dioxide equivalent. This reduced to 2 t as a result of complete combustion of methane. The global warming potential saving of a bioenergy plant across a 20-year life cycle is 217 t of carbon dioxide equivalent, which is 11 t per year. The global warming potential of the resultant digestate is zero and from construction materials is less than 1% of total global warming potential. When the biogas is used as a fuel for cooking, the global warming potential will reduce by 83% compare with the traditional wood biomass cooking system. The total 80 MJ of energy that can be produced from a 3.2 m3 anaerobic digestion plant would replace 1.9 t of fuel wood or 632 kg of kerosene currently used annually in Bangladesh. The digestate can also be used as a nutrient rich fertiliser substituting more costly inorganic fertilisers, with no global warming potential impact

Arsenic Contamination in Food-chain: Transfer of Arsenic into Food Materials Through Groundwater Irrigation

Arsenic contamination in groundwater in Bangladesh has become an additional concern vis-\ue0-vis its use for irrigation purposes. Even if arsenic-safe drinking-water is assured, the question of irrigating soils with arsenic-laden groundwater will continue for years to come. Immediate attention should be given to assess the possibility of accumulating arsenic in soils through irrigation-water and its subsequent entry into the food-chain through various food crops and fodders. With this possibility in mind, arsenic content of 2,500 water, soil and vegetable samples from arsenic-affected and arsenic-unaffected areas were analyzed during 1999-2004. Other sources of foods and fodders were also analyzed. Irrigating a rice field with groundwater containing 0.55 mg/L of arsenic with a water requirement of 1,000 mm results in an estimated addition of 5.5 kg of arsenic per ha per annum. Concentration of arsenic as high as 80 mg per kg of soil was found in an area receiving arsenic-contaminated irrigation. A comparison of results from affected and unaffected areas revealed that some commonly-grown vegetables, which would usually be suitable as good sources of nourishment, accumulate substantially-elevated amounts of arsenic. For example, more than 150 mg/kg of arsenic has been found to be accumulated in arum (kochu) vegetable. Implications of arsenic ingested in vegetables and other food materials are discussed in the paper

A Mitigation Approach to Alleviate Arsenic Accumulation in Rice through Balanced Fertilization

Pot experiments with boro and aman season rice on the same soils treated with arsenic contaminated irrigation water and using balanced fertilizer or not revealed that balance fertilization could be a strategy to mitigate arsenic accumulation in rice grain. The study also revealed that there is a carryover effect of As applied through irrigation in the boro season to the subsequent aman season rice. This carryover effect too, could be minimized with balanced fertilization

Understanding bioenergy production and optimisation at the nanoscale - a review

Nanotechnology has an increasingly large impact on a wide range of biotechnological, pharmacological and pure technological applications. Its current use in bioenergy production from biomass is very limited. This paper examines the potential interrelationships between nanotechnology and bioenergy production through a comprehensive literature review and analysis of data from biomass characterisation studies. The aim of this review is to indicate how nanotechnology can be applied in biomass-to-bioenergy conversion. This study shows currently nanotechnology has been applied in the production of only two types of biomass, i.e. sludge and algae. Hence, interaction of nanomaterials with active sludge and algal cells were examined. Our extensive literature review indicates that anaerobic digestion process in sludge can potentially be enhanced by using magnetite nanoparticles, which gives higher methane yields. On the other hand, nanosilver reduces growth and causes adverse effects on the morphology of green algae. This process for bioenergy generation has already been successfully applied to sludge and algae biomass. Our study confirms that the process can also be used in the production of bioenergy from the other biomasses, such as agricultural wastes and industrial residues. Outcomes of this work will be an important tool for implementing nanotechnology in bioenergy research. © 2016 Taylor & Franci

Fertilizer effects on yield, nitrogen content and amino acid composition of maize grain

International audienc

Arsenic Mitigation Approach in Soil by Some Indigenous Sources of Biochar Made at Low Pyrolysis Temperature

Biochar is being reported now a-days to potentially reduce the bioavailability of arsenic (As). A pot culture and an in vitro incubation study was conducted to evaluate the efficacy of biochar produced from different sources (viz., cow dung, poultry manure and sewage sludge) at low temperature (250ºC) on the phytoavailability of As. An experimental setup containing two sets of treatments (As and no-As) were followed. Biochar was applied at the rate of 5t/ha to the soils that received As treatment at a rate of 1mg/L As (80% arsenite and 20% arsenate). After 45 days of growth of Kalmi (Ipomoea aquatica), plant and soil samples were analyzed. Biochar insignificantly increased plant growth.  Biochar was observed to be more effective in alleviating As accumulation in plant than the biomass. The incubation study was done for 0, 15, 30 and 45 days to diagnose the temporal sorption of water soluble As by biochars. All the biochar materials reduced As availability than their corresponding biomass materials. Measurement of different physical (e.g. surface area, morphology, elemental composition), chemical (CEC, nutrient content, As) and physicochemical (pH) properties of the biochar showed that through pyrolysis process nitrogen(N), sulfur (S), phosphorus (P) content and pH of the biomass decreased and on the other hand potassium (K), As content and CEC increased. Slow pyrolysis process and variation in biomass material influenced the properties and behavior of biochar. Among the biochars, sewage sludge biochar showed the maximum and cowdAsung showed the minimum sorption capacity for As. Due to the threat of As to health and environment, this topic requires more consideration.  Moreover, covering all the above issues, this study identifies research gaps in the use of biochar as an adsorbent for As and proposes potential areas for future application of biochar