In-situ monitoring of chromium cytotoxicity in sugarcane

The potential of in-situ monitoring of cytotoxic effects of chromium through root-tip assay was studied in a sugarcane cultivar CoLk 8102 (Saccharum spp. hybrid). Sugarcane setts supplied with graded concentrations of chromium (VI), exhibited a reduction of 85.92 and 95.10 % in mean root length at 40 and 80 ppm Cr dosages along with 61.25 and 82.50% reduction in mean root number/node respectively. Mitotic index of root tip cells of treated setts declined and the frequency of aberrant mitotic phases increased pari passu to the increasing chromium concentration. To compare and quantify the effect of graded chromium dosages on frequency of chromosome aberrations vis-à-vis inhibition of mitotic activity, a 'Decretion factor' (D.F.) has been used for the first time. The value of DF increased with the increase in the chromium dosages. The increase in chromosome aberration frequency was low at low chromium dosages (1 or 2 ppm), but the high Cr dosages (40 and 80 ppm), induced sharp reduction in mitotic efficiency of root system along with anomalies in the process of cell division and induced chromosome aberrations in sugarcane root meristem, which in turn affected the over all plant growth.     

Controlling environmental pollution: dynamic role of fiscal decentralization in CO2 emission in Asian economies

Environmental Science and Pollution Research - The “environment” has become one of the important and debatable topics of the world and policymakers identifying the new predictors of CO2...     

Bacterial diversity in mining and non-mining regions with emphasis on plant growth-promoting traits

A total of 20 soil samples were collected from mining and non-mining areas of coal field regions of Dhanbad, India. These samples were grown on different types of selective media and a total of 141 isolates, each having plant growth-promoting (PGP) characteristics were obtained. The isolates were further tested for PGP traits (phosphate solubilisation, production of indole acetic acid, hydrogen cyanide, ammonia and siderophores) and a biochemical analysis was done to determine the prevalent species of the region. All the strains selected showed at least two PGP characteristics, which indicated that they can be used as plant growth promoters. Bacillus and Pseudomonas species were prevalent in both mining and non-mining areas, whereas Rhizobium, Azospirillum and Azotobacter were found mostly in the non-mining area. A total of 48 Bacillus, 29 Pseudomonas, 4 Rhizobium, 11 Azospirillum and 10 Azotobacter species were obtained from the two selected regions. The soil samples from the mining region were poor in nutrient content and thus relatively lower numbers of PGP isolates were attained.     

Transient design of landfill liquid addition systems

This study presents the development of design charts that can be used to estimate lateral and vertical spacing of liquids addition devices (e.g., vertical well, horizontal trenches) and the operating duration needed for transient operating conditions (conditions until steady-state operating conditions are achieved). These design charts should be used in conjunction with steady-state design charts published earlier by Jain et al., 2010a, Jain et al., 2010b. The data suggest that the liquids addition system operating time can be significantly reduced by utilizing moderately closer spacing between liquids addition devices than the spacing needed for steady-state conditions. These design charts can be used by designers to readily estimate achievable flow rate and lateral and vertical extents of the zone of impact from liquid addition devices, and analyze the sensitivity of various input variables (e.g., hydraulic conductivity, anisotropy, well radius, screen length) to the design. The applicability of the design charts, which are developed based on simulations of a continuously operated system, was also evaluated for the design of a system that would be operated intermittently (e.g., systems only operated during facility operating hours). The design charts somewhat underestimates the flow rate achieved and overestimates the lateral extent of the zone of impact over an operating duration for an intermittently operated system. The associated estimation errors would be smaller than the margin of errors associated with measurement of other key design inputs such as waste properties (e.g., hydraulic conductivity) and wider variation of these properties at a given site due to heterogeneous nature of waste.     

Steady-state design of horizontal systems for liquids addition at bioreactor landfills

The key parameters for designing a horizontal source (horizontal trenches, infiltration ponds, infiltration galleries or blankets) for steady state are the rate liquids can be added to the source, the lateral and vertical extents of the zone of impact of the source, and the liquids volume needed to wet the waste within the zone of impact at steady state. This paper presents charts that a designer can use to estimate these key parameters as functions of source dimensions, injection pressure, and municipal solid waste properties (porosity, hydraulic conductivity, and anisotropy) for designing a new or analyzing an existing horizontal source system for liquids addition to landfilled waste. SEEP/W was used to model liquids flow from a horizontal source in a range of conditions practically encountered for such systems. The governing equation (Richard’s equation) and the boundary conditions were analyzed to formulate dimensionless variables by normalizing the design parameters (flow rate, injection pressure, the lateral zone of impact, injection pressure, and the added liquids volume) with the waste properties and source dimensions. The simulation results were transformed to the respective dimensionless forms and presented in design charts to estimate the key design parameters as functions of the source dimensions, waste properties, and injection pressure. The presentation of the modeling results in the dimensionless form facilitates their use beyond the conditions modeled. A solved example is presented to demonstrate the use of the design charts. The approach presented in the paper should be considered as approximate and designers should use their judgement and experience when using these charts for designing a horizontal liquids addition system for a specific site.     

Exposure and health risks potentially posed to petroleum storage tank cleaners by volatile organic compounds

This study models and assesses the significance of risks to health potentially posed to individuals exposed to volatile organic compounds (VOCs) due to being occupationally engaged in cleaning petroleum storage tanks. Exposure processes include hydrocarbon vapor inhalation, ingestion via hand-to-mouth contact, and dermal exposure. Under confined space entry regulations, tank cleaners must wear protective clothing and a breathing apparatus. However, such regulations are recent and sometimes violated. Several factors were found to influence exposure of unprotected individuals cleaning tanks. One factor is climate. This paper reports on a study of tanks in south Texas, which is sunny and hot during most of the year. Solar irradiation of metal surfaces may elevate internal temperatures above ambient air temperatures. Vaporization then elevates airborne hydrocarbon concentrations, and ventilation reduces them, producing a dynamic equilibrium. Human entry, however, disturbs this equilibrium by agitating petroleum residuals. Based upon the above considerations, we have modeled petroleum fuel storage tank dynamics in a case study. We considered three cases: manways closed, manways open, and manways actively ventilated. For CASE I, the concentration of each pollutant in the vapor phase was calculated using Raoult's Law. CASE II and CASE III applied Raoult's Law and also evaluated a mass balance via a mass transfer coefficient derived using the Reynolds Number and the Schmidt Number. Based upon empirical data, the velocity of the air within the tank was assumed to be 1.6 mph. Outputs of the case study included the steady-state concentration of each constituent and time required to reach it. Health risk assessment was conducted to quantify non-cancer risks posed by individual substances (the hazard quotient, HQ) and by simultaneous and/or sequential exposure to multiple substances (the hazard index, HI). During hot months, gross exceedances of acceptability criteria for acute and chronic exposures to mixed solvent vapors occurred. The HI exceeded the acceptability criterion by more than three orders of magnitude. The HI for chronic occupational neurological risks exceeded the acceptability criterion by more than two orders of magnitude. This result is consistent with observed neurological deficits among tank cleaners, such as depression of performance on memory tests among crew members who had worked during hot months. Finally, in such instances, eight-hour time-weighted average mixed-solvent vapor concentrations can exceed half of lethal levels, suggesting that tank cleaners can potentially approach lethal exposure routinely during hot seasons.     

Concentrations of selected metals in blood,serum, and urine among US adult exclusive users of cigarettes,cigars, and electronic cigarettes

Data from National Health and Nutrition Examination Survey for 2013–2014 were used to compare observed levels of selected metals in blood, serum, and urine among US adults aged ≥20 years for exclusive cigar, cigarettes, and e-cigarette users. Adjusted geometric means for e-cigarette users were found to be higher than for cigar users for blood manganese (10.3 vs. 7.9 µg/L, p = 0.02). Cigar users were found to have lower adjusted geometric means than cigarette users for urine cobalt (0.22 vs. 0.4 µg/L, p = 0.04) and urine antimony (0.03 vs. 0.06 µg/L, p = 0.03). Adjusted levels of blood selenium, serum copper, selenium, and zinc, and urine arsenic, barium, molybdenum, tin, strontium, thallium, tungsten, and uranium were found to be comparable among cigarettes only, cigar only, and electronic cigarettes only users. However, irrespective of the comparative levels of these metals among cigar, cigarette, and e-cigarette users, focus must be to assess the short- and long-term health effects of the exposure to these metals particularly nanoparticles via inhalation from e-cigarette aerosols.     

Effect of hypoxia on the circulating levels of essential mineral elements in rats

Changes occurring in concentrations of certain trace metals and electrolytes viz. chromium, copper, zinc, sodium, potassium, calcium, magenesium and chloride in plasma of rats exposed to intermittent hypobaric hypoxia were evaluated. Batches of Sprague-Dowley rats (12 in each group) were exposed for 1, 7,14 and 21 days to a simulated altitude 7,620 m for 6 h per day and one group of unexposed animals was kept as control. There was a significant rise of 153% in plasma chromium levels of 1 day exposed group in comparison to the unexposed group which tends to normalise on subsequent exposure. There was a gradual increase in plasma copper levels of 9.0, 28.2, 62.6 and 65.6% respectively in 1,7,14 and 21 days exposed rats in comparison to unexposed rats. On the other hand plasma zinc levels were seen to be decreasing during entire exposure. Plasma sodium levels decreased initially in 1 and 7 day exposed rats and increased in later groups whereas plasma potassium levels of exposed groups remained low in comparison to unexposed group. Chloride levels were found to be elevated in 14 and 21 day exposed groups. The plasma calcium and magnesium levels were higher in all exposed groups over unexposed groups. Changes in chromium, copper and zinc observed in the present study during exposure to hypoxic stress may be responsible for the hyperglycemia and anorexia encountered during intial phase of high altitude acclimatisation.     

Regression models to estimate total concentrations of polybrominated diphenyl ethers: data from NHANES 2003–2004

The objective of this study was to develop regression models to estimate the total concentration of polybrominated diphenyl ethers in serum based on the known concentrations of a limited number of congeners. Because of the possible adverse health effects associated with the exposure to polybrominated diphenyl ethers, it is of interest to know their total concentrations. Data from the National Health and Nutrition Examination Survey for 2003–2004 (N = 1859) were used to develop regression models to estimate both wet weight and lipid-adjusted total concentrations. Only the knowledge of three congeners, namely, 2,2′,4,4′-tetrabromodiphenyl ether, 2,2′,4,4′,5-pentadibromodiphenyl ether, and 2,2′,4,4′,5,5′-hexabromodiphenyl ether was required to use these models. Other than the concentrations of these three congeners, age, gender, and smoking status were the only information needed to use these models. Optionally, models were developed that could also use the race/ethnicity of the participants. All models explained more than 98% of the known variability in the observed total concentration levels. Over 98% of the model generated, predicted values were found to be within 5% of the observed values.