Enteric methane mitigation technologies for ruminant livestock: a synthesis of current research and future directions

Enteric methane (CH₄) emission in ruminants, which is produced via fermentation of feeds in the rumen and lower digestive tract by methanogenic archaea, represents a loss of 2% to 12% of gross energy of feeds and contributes to global greenhouse effects. Globally, about 80 million tonnes of CH₄ is produced annually from enteric fermentation mainly from ruminants. Therefore, CH₄ mitigation strategies in ruminants have focused to obtain economic as well as environmental benefits. Some mitigation options such as chemical inhibitors, defaunation, and ionophores inhibit methanogenesis directly or indirectly in the rumen, but they have not confirmed consistent effects for practical use. A variety of nutritional amendments such as increasing the amount of grains, inclusion of some leguminous forages containing condensed tannins and ionophore compounds in diets, supplementation of low-quality roughages with protein and readily fermentable carbohydrates, and addition of fats show promise for CH₄ mitigation. These nutritional amendments also increase the efficiency of feed utilization and, therefore, are most likely to be adopted by farmers. Several new potential technologies such as use of plant secondary metabolites, probiotics and propionate enhancers, stimulation of acetogens, immunization, CH₄ oxidation by methylotrophs, and genetic selection of low CH₄-producing animals have emerged to decrease CH₄ production, but these require extensive research before they can be recommended to livestock producers. The use of bacteriocins, bacteriophages, and development of recombinant vaccines targeting archaeal-specific genes and cell surface proteins may be areas worthy of investigation for CH₄ mitigation as well. A combination of different CH₄ mitigation strategies should be adopted in farm levels to substantially decrease methane emission from ruminants. Evidently, comprehensive research is needed to explore proven and reliable CH₄ mitigation technologies that would be practically feasible and economically viable while improving ruminant production.     

Development of an Ozone Forecasting Model for Non-Attainment Areas in the State of Ohio

Ground level ozone is responsible for the formation ofsmog, and for a variety of adverse effects on bothhuman and plant life. High concentrations of groundlevel ozone occur during the summer months. This paperdescribes the development of a model to forecast themaximum daily concentration of ozone as a function ofthe maximum surface temperature, for ozonenon-attainment regions in Ohio. The model wasdeveloped by statistical analysis of existing data.Site-specific models were developed initially. Theverification and evaluation of the performancecriteria of the model at each site were explored bycomparing the model with an independent datasetcollected from that site. A generalized statewidemodel was developed from the site-specific models. Theperformance criteria of this model were verified andevaluated by employing the same independent datasetsemployed for the site-specific models. An exceedencemodel to predict the occurrence of ozone exceedencesover 100 ppb has also been presented.     

Concentrations of heavy metals and aquatic macrophytes of Govind Ballabh Pant Sagar an anthropogenic lake affected by coal mining effluent

Five heavy metals Cu, Cd, Mn, Pb and Hg were found in high concentration from three sampling sites located in Asia’s largest anthropogenic lake Govind Ballabh Pant GBP Sagar. Concentrations of these heavy metals were measured in Water, bottom sediment and in different parts of the aquatic macrophytes collected from the reservoir. Plants collected from the lake were Eichhornia crassipes, Azolla pinnata, Lemna minor, Spirodela polyrrhiza, Potamogeton pectinatus, Marsilea quadrifolia, Pistia stratiotes, Ipomea aquqtica, Potamogeton crispus, Hydrilla verticillata and Aponogeton natans. These plants have shown the high concentrations of Cu, Cd, Mn, Pb and Hg in their different parts due to bioaccumulation. In general plant roots exhibited higher concentrations of heavy metals than corresponding sediments. A comparison between different morphological tissues of the sampled plants reveled the metal concentration in following order roots > leaves. Analyses of bottom sediment indicated the higher concentrations of Cd, Mn, Cu and Pb. Strong positive correlations were obtained between the metals in water and in plants as well as between metal in sediment and in plants. Indicating the potential of these plants for pollution monitoring of these metals.     

An eco-sustainable green approach for heavy metals management: two case studies of developing industrial region

Multifaceted issues or paradigm of sustainable development should be appropriately addressed in the discipline of environmental management. Pollution of the biosphere with toxic metals has accelerated dramatically since the beginning of the Industrial Revolution. In present review, comparative assessment of traditional chemical technologies and phytoremediation has been reviewed particularly in the context of cost-effectiveness. The potential of phytoremediation and green chemicals in heavy metals management has been described critically. Further, the review explores our work on phytoremediation as green technology during the last 6 years and hand in hand addresses the various ecological issues, benefits and constraints pertaining to heavy metal pollution of aquatic ecosystems and its phytoremediation as first case study. Second case study demonstrates the possible health implications associated with use of metal contaminated wastewater for irrigation in peri-urban areas of developing world. Our researches revealed wetland plants/macrophytes as ideal bio-system for heavy metals removal in terms of both ecology and economy, when compared with chemical treatments. However, there are several constraints or limitations in the use of aquatic plants for phytoremediation in microcosm as well as mesocosm conditions. On the basis of our past researches, an eco-sustainable model has been proposed in order to resolve the certain constraints imposed in two case studies. In relation to future prospect, phytoremediation technology for enhanced heavy metal accumulation is still in embryonic stage and needs more attention in gene manipulation area. Moreover, harvesting and recycling tools needs more extensive research. A multidisciplinary research effort that integrates the work of natural sciences, environmental engineers and policy makers is essential for greater success of green technologies as a potent tool of heavy metals management.     

Critical review of EPS production, synthesis and composition for sludge flocculation

Extracellular polymeric substances(EPS) produced by microorganisms represent biological macromolecules with unfathomable potentials and they are required to be explored further for their potential application as a bioflocculant in various wastewater sludge treatment. Although several studies already exist on biosynthetic pathways of different classical biopolymers like alginate and xanthan, no dedicated studies are available for EPS in sludge. This review highlights the EPS composition, functionality, and biodegradability for its potential use as a carbon source for production of other metabolites. Furthermore, the effect of various extraction methods(physical and chemical) on compositional, structural, physical and functional properties of microbial EPS has been addressed. The vital knowledge of the effect of extraction method on various important attributes of EPS can help to choose the suitable extraction method depending upon the intended use of EPS. The possible use of different molecular biological techniques for enhanced production of desired EPS was summarized.     

Deep eutectic solvents in the transformation of biomass into biofuels and fine chemicals: a review

Environmental Chemistry Letters - The global energy demand has been projected to rise over 28% by 2040, calling for more renewable resources such as lignocellulosic biomass to produce biofuels, and...     

Metal- and ionic liquid-based photocatalysts for biodiesel production: a review

Environmental Chemistry Letters - Diminishing petroleum reserves, increasing carbon emissions, and the growing demand for fuels are calling for alternative fuels. Global diesel consumption...     

Class-2 hazmat transportation consequence assessment on surrounding population

The transportation of hazardous materials by road is an utmost necessity of the world for the societal benefits, but at the same time the activity is inherently dangerous. Incidents involving hazardous material (hazmat) cargo particularly the class-2 materials can lead to severe consequences in terms of fatalities, injuries, evacuation, property damage and environmental degradation. The rationale behind considering class-2 hazmats is that they pose the greatest danger to the people and property along the transport route because of their storage condition on the transport vessel. They are stored either in pressurized vessels or in cryogenic containers. Any external impact due to collision may cause catastrophic failure of transport vessels, known as BLEVE (Boiling Liquid Expanding Vapour Explosion) with devastating consequences. Further, any continuous release from containment may cause what is known as ‘Unconfined Vapour Cloud Explosion’ (UVCE). Historically frequency of BLEVE occurrence is of the order of 1 × 10⁻⁶ per year or less, but other release scenarios e.g. a large vapour or liquid leaks are more probable and could also have devastating effects on the surrounding population. As such, the paper discussed various event scenarios and the consequences taking examples of a class-2.1 material (1,3 butadiene) and another class-2.3 (ammonia) hazmat. Comparative analysis suggests that per ton basis a rupture of ammonia tanker gives rise to larger impact areas and poses larger lethality risks compared to 1,3 butadiene as far as toxic effects are concerned. Besides, from fireball fatality on similar basis propylene causes higher consequence distance than LPG followed by ethylene oxide and 1,3 butadiene. The impact zone study results may be utilized as inputs for identifying the potential vulnerable area on a GIS enabled map, along a designated State highway route passing through an important industrial corridor in western India.