Arsenic bioaccumulation in rice and edible plants and subsequent transmission through food chain in Bengal basin: a review of the perspectives for environmental health

Arsenic (As) is a metalloid that poses serious environmental threats due to its behemoth toxicity and wide abundance. The use of arsenic-contaminated groundwater for irrigation purpose in crop fields elevates arsenic concentration in surface soil and in the plants. In many arsenic-affected countries, including Bangladesh and India, rice is reported to be one of the major sources of arsenic contamination. Rice is much more efficient at accumulating arsenic into the grains than other staple cereal crops. Rice is generally grown in submerged flooded condition, where arsenic bioavailability is high in soil. As arsenic species are phytotoxic, they can also affect the overall production of rice, and can reduce the economic growth of a country. Once the foodstuffs are contaminated with arsenic, this local problem can gain further significance and may become a global problem, as many food products are exported to other countries. Large-scale use of rainwater in irrigation systems, bioremediation by arsenic-resistant organisms and hyperaccumulating plants, and the aerobic cultivation of rice are some possible ways to reduce the extent of bioaccumulation in rice. Investigation on a complete food chain is urgently needed in the arsenic-contaminated zones, which should be our priority in future researches.     

Green synthesis,activation and functionalization of adsorbents for dye sequestration

Environmental Chemistry Letters - The release of recalcitrant dyes into the biosphere is a threat because of pollution and environmental health issues. Adsorption using commercial activated carbon...     

A review on recent progress in observations,sources, classification and regulations of PM<Subscript>2.5</Subscript> in Asian environments

Natural and human activities generate a significant amount of PM_2.5 (particles ≤2.5 μm in aerodynamic diameter) into the surrounding atmospheric environments. Because of their small size, they can remain suspended for a relatively longer time in the air than coarse particles and thus can travel long distances in the atmosphere. PM_2.5 is one of the key indicators of pollution and known to cause numerous types of respiratory and lung-related diseases. Due to poor implementation of regulations and a time lag in introducing the vehicle technology, levels of PM_2.5 in most Asian cities are much worse than those in European environments. Dedicated reviews on understanding the characteristics of PM_2.5 in Asian urban environments are currently missing but much needed. In order to fill the existing gaps in the literature, the aim of this review article is to describe dominating sources and their classification, followed by current status and health impact of PM_2.5, in Asian countries. Further objectives include a critical synthesis of the topics such as secondary and tertiary aerosol formation, chemical composition, monitoring and modelling methods, source apportionment, emissions and exposure impacts. The review concludes with the synthesis of regulatory guidelines and future perspectives for PM_2.5 in Asian countries. A critical synthesis of literature suggests a lack of exposure and monitoring studies to inform personal exposure in the household and rural areas of Asian environments.     

Effects of in utero di-butyl phthalate and butyl benzyl phthalate exposure on offspring development and male reproduction of rat

The study was conducted to assess the effects of in utero di-butyl phthalate (DBP) and butyl benzyl phthalate (BBP) exposure during late gestation on offspring’s development and reproductive system of male rats. Pregnant rats were treated orally with DBP (2, 10, 50 mg/kg), BBP (4, 20, 100 mg/kg), and diethylstilbestrol (DES) 6 μg/kg (positive control) from GD14 to parturition. A significant reduction in dams’ body weight on GD21 in DBP-, BBP-, and DES-treated groups was observed. The gestation length was considerably elevated in the treated groups. Decline in male pups’ body weight was significant at PND75 in DBP- (50 mg/kg), BBP- (20,100 mg/kg), and DES-treated groups. The weight of most of the reproductive organs and sperm quality parameters was impaired significantly in DBP- (50 mg/kg) and BBP- (100 mg/kg) treated groups. Further, a non-significant decline in testicular spermatid count and daily sperm production was also monitored in treated groups. A significant reduction in serum testosterone level in BBP (100 mg/kg), whereas the testicular activity of 17β-HSD was declined non-significantly in the treated groups with respect to control. The data suggests that DBP and BBP exposure during late gestation period might have adverse effects on offspring’s development, spermatogenesis, and steroidogenesis in adult rats.     

Mobile measurement of methane and hydrogen sulfide at natural gas production site fence lines in the Texas Barnett Shale

Production of natural gas from shale formations is bringing drilling and production operations to regions of the United States that have seen little or no similar activity in the past, which has generated considerable interest in potential environmental impacts. This study focused on the Barnett Shale Fort Worth Basin in Texas, which saw the number of gas-producing wells grow from 726 in 2001 to 15,870 in 2011. This study aimed to measure fence line concentrations of methane and hydrogen sulfide at natural gas production sites (wells, liquid storage tanks, and associated equipment) in the four core counties of the Barnett Shale (Denton, Johnson, Tarrant, and Wise). A mobile measurement survey was conducted in the vicinity of 4788 wells near 401 lease sites, representing 35% of gas production volume, 31% of wells, and 38% of condensate production volume in the four-county core area. Methane and hydrogen sulfide concentrations were measured using a Picarro G2204 cavity ring-down spectrometer (CRDS). Since the research team did not have access to lease site interiors, measurements were made by driving on roads on the exterior of the lease sites. Over 150 hr of data were collected from March to July 2012. During two sets of drive-by measurements, it was found that 66 sites (16.5%) had methane concentrations >3 parts per million (ppm) just beyond the fence line. Thirty-two lease sites (8.0%) had hydrogen sulfide concentrations >4.7 parts per billion (ppb) (odor recognition threshold) just beyond the fence line. Measured concentrations generally did not correlate well with site characteristics (natural gas production volume, number of wells, or condensate production). t tests showed that for two counties, methane concentrations for dry sites were higher than those for wet sites. Follow-up study is recommended to provide more information at sites identified with high levels of methane and hydrogen sulfide.

Implications:Information regarding air emissions from shale gas production is important given the recent increase in number of wells in various regions in the United States. Methane, the primary natural gas constituent, is a greenhouse gas; hydrogen sulfide, which can be present in gas condensate, is an odor-causing compound. This study surveyed wells representing one-third of the natural gas production volume in the Texas Barnett Shale and identified the percent of sites that warrant further study due to their fence line methane and hydrogen sulfide concentrations.     

Long-term effect of rice-based farming systems on soil health

Integrated rice–fish culture, an age-old farming system, is a technology which could produce rice and fish sustainably at a time by optimizing scarce resource use through complementary use of land and water. An understanding of microbial processes is important for the management of farming systems as soil microbes are the living part of soil organic matter and play critical roles in soil C and N cycling and ecosystem functioning of farming system. Rice-based integrated farming system model for small and marginal farmers was established in 2001 at Central Rice Research Institute, Cuttack, Odisha. The different enterprises of farming system were rice–fish, fish–fingerlings, fruits, vegetables, rice–fish refuge, and agroforestry. This study was conducted with the objective to assess the soil physicochemical properties, microbial population, carbon and nitrogen fractions, soil enzymatic activity, and productivity of different enterprises. The effect of enterprises induced significant changes in the chemical composition and organic matter which in turn influenced the activities of enzymes (urease, acid, and alkaline phosphatase) involved in the C, N, and P cycles. The different enterprises of long-term rice-based farming system caused significant variations in nutrient content of soil, which was higher in rice–fish refuge followed by rice–fish enterprise. Highest microbial populations and enzymatic properties were recorded in rice–fish refuge system because of waterlogging and reduced condition prolonged in this system leading to less decomposition of organic matter. The maximum alkaline phosphatase, urease, and FDA were observed in rice–fish enterprise. However, highest acid phosphatase and dehydrogenase activity were obtained in vegetable enterprise and fish–fingerlings enterprise, respectively.     

Environmental assessment of laser assisted manufacturing: case studies on laser shock peening and laser assisted turning

Laser assisted manufacturing processes, when compared with traditional manufacturing processes, have the potential to reduce cost, increase surface resistance to wear and fatigue, extend part/tool life, and expand the range of manufacturable materials. These processes have found niche applications in automotive, aerospace, and defense industries. However, very limited research has been conducted to evaluate and compare the environmental performance of laser assisted processes with traditional methods. This paper conducts case studies on two representative laser based processes, i.e. laser shock peening of 7075-T7351 Aluminum and laser assisted turning of compacted graphite iron. Life cycle assessment is used to benchmark the environmental performance of these two processes to conventional processes, i.e. shot peening and turning, respectively. The life cycle inventory of both the laser based processes and conventional processes are developed using SimaPro 7.1 and the Ecoinvent 2.0 database and life cycle impact assessment is performed using US EPA TRACI. The results of this study show that the environmental performance of the two laser based processes is significantly better than conventional processes. For laser shock peening of aluminum, contribution analysis indicates that this is mainly due to the significant extension of fatigue life of the workpiece being treated. For laser assisted turning of compacted graphite iron, the improved performance is mainly due to the extended tool life since cutting tool manufacturing is an energy intensive process. Development of high-power laser with a lower wavelength (e.g. direct diode system) could eliminate the use of paint in laser assisted turning. This, along with improved wall plug efficiency, makes laser assisted turning even more environmentally benign compared to conventional process. A brief cost analysis suggests that both laser shock peening and laser assisted turning can be economically viable with payback period less than three years for niche applications.     

Regulation of autophagy in rat hepatocytes treated in vitro with low concentration of mercury

Several proteins are implicated in the regulation of autophagy in cells under various physiological and pathological conditions. Recently it was found that in vitro initiation of autophagy in 5 μM mercuric chloride (HgCl₂) treated rat hepatocytes occurred within 30 min of incubation. The aim of this study was to monitor the autophagy–ubiquitination link to determine the regulatory mechanisms underlying autophagy at a concentration of 5 μM HgCl₂. Autophagic cell death was evidenced by the presence of LC3B positive hepatocytes throughout the incubation period of 4 hr. Autophagosome maturation occurred following 1 hr of metal treatment accompanied by an enhanced expression of several regulatory proteins such as p62, Keap1, and caspase-8, which drive the hepatocytes toward autophagy. In addition, the rate of increase in down-regulation in a p38 expression was significantly higher than that of extracellular signal-regulated kinase (ERK) at 1 hr incubation, followed by a significant decline in the p38 level at 2 and 4 hr following metal treatment. In contrast, the expression of ERK remained higher than that of p38 at 2 and 4 hr. Data indicate that intracellular activation of the major regulatory proteins such as LC3B, caspase-8, Keap1, p62, ERK, and p38 modulates autophagy through ubiquitination in rat hepatocytes exposed to low concentrations of Hg.     

Study on chemical kinetics and catalytic cracking of tar from gasification of rice straw using various catalysts

Journal of Material Cycles and Waste Management - The tar formed within the producer gas is a major problem in the biomass gasification process. The catalytic cracking of tar is the best method to...