Solar ponds—a mini review

Environmental Science and Pollution Research - A solar pond is a simple system that collects and stores heat for thermal and electrical applications. Heat storage and heat extraction are the key...     

RESEARCH: Land Use Characteristics and Water Quality: A Methodology for Valuing of Forested Buffers

In this study, water quality and basin characteristics data from different basins of the Fish River basin, Baldwin County, Alabama, were used to develop a valuation model. This valuation model is based on the effectiveness of “contributing zones” identified and delineated using methods described by Basnyat and others (Environmental Management]1999] 23(4):539–549). The “contributing zone” delineation model suggests that depending on soil permeability, soil moisture, depth to water table, slope, and vegetation, buffer widths varying from 16 m to 104 m must be maintained to assimilate or detain more than 90% of the nitrate passing through the buffers. The economic model suggests the value of retiring lands (to create the buffers) varies from $0 to $3067 per ha, depending on the types of crops currently grown. The total value of retiring all areas identified by the contributing zone model is $1,125,639 for the study area. This land value will then form the basis for estimates of the costs of land management options for improving (or maintaining) water quality throughout the study area.     

An evaluation of mass absorption cross-section for optical carbon analysis on Teflon filter media

Black carbon (BC) or elemental carbon (EC) is a by-product of incomplete fuel combustion, and contributes adversely to human health, visibility, and climate impacts. Previous studies have examined nondestructive techniques for particle light attenuation measurements on Teflon® filters to estimate BC. The incorporation of an inline Magee Scientific OT21 transmissometer into the MTL AH-225 robotic weighing system provides the opportunity to perform optical transmission measurements on Teflon filters at the same time as the gravimetric mass measurement. In this study, we characterize the performance of the inline OT21, and apply it to determine the mass absorption cross-section (MAC) of PM_2.5 BC across the United States. We analyzed 5393 archived Teflon® filters from the Chemical Speciation Network (CSN) collected during 2010–2011 and determined MAC by comparing light attenuation on Teflon® filters to corresponding thermal EC on quartz-fiber filters. Results demonstrated the importance of the initial transmission (I₀) value used in light attenuation calculations. While light transmission varied greatly within filter lots, the average I₀ of filter blanks during the sampling period provided an estimate for archived filters. For newly collected samples, it is recommended that filter-specific I₀ measurements be made (i.e., same filter before sample collection). The estimated MAC ranged from 6.9 to 9.4 m²/g and varied by region and season across the United States, indicating that using a default value may lead to under- or overestimated BC concentrations. An analysis of the chemical composition of these samples indicated good correlation with EC for samples with higher EC content as a fraction of total PM_2.5 mass, while the presence of light-scattering species such as crustal elements impacted the correlation affecting the MAC estimate. Overall, the method is demonstrated to be a quick, cost-effective approach to estimate BC from archived and newly sampled Teflon® filters by combining both gravimetric and BC measurements.

Implications: Robotic optical analysis is a valid, cost-effective means to obtain a vast amount of BC data from archived and current routine filters. A tailored mass absorption cross-section by region and season is necessary for a more representative estimate of BC. Initial light transmission measurements play an important role due to the variability in blank filter transmission. Combining gravimetric mass and BC analysis on a single Teflon® filter reduces costs for monitoring agencies and maximizes data collection.     

Biosequestration of lead using Bacillus strains isolated from seleniferous soils and sediments of Punjab

The present study was conducted to isolate and explore bacterial strains with a potential to sequester lead (Pb) and tolerate other heavy metals from industrial effluents and sediments. Out of the six bacterial strains isolated from seleniferous sites of Punjab, three isolates (RS-1, RS-2, and RS-3) were screened out for further growth-associated lead sequestration and molecular characterization on the basis of their tolerance toward lead and other heavy metals. Biomass and cell-free supernatant were analyzed for lead contents using ICP-MS after growth-associated lead sequestration studies in tryptone soya broth (pH?=?7.2?±?0.2) under aerobic conditions at 37 °C temperature. Almost 82 % and 70 % divalent lead was sequestered in cell pellets of RS-1 and RS-3, respectively while only 45 % of lead was found in cell pellet of RS-2 in the first 24 h. However, significant biosequestration of lead was observed in RS-2 after 48 h of incubation with concomitant increase in biomass. Simultaneously, morphological, biochemical, and physiological characterization of selected strains was carried out. 16S rRNA gene sequence of these isolates revealed their phylogenetic relationship with class Bacillaceae, a low G + C firmicutes showing 98 % homology with Bacillus sp.     

Future year ozone source attribution modeling study using CMAQ-ISAM

ABSTRACT

To achieve the current United States National Ambient Air Quality Standards (NAAQS) attainment level for ozone or particulate matter, current photochemical air quality models include tools to determine source apportionment and/or source sensitivity. Previous studies by the authors have used the Ozone and Particulate Matter Source Apportionment Technology and Higher-order Decoupled Direct Method probing tools in CAMx to investigate these source-receptor relationships for ozone. The recently available source apportionment for CMAQ, referred to as the Integrated Source Apportionment Method (ISAM), was used in this study to conduct future year (2030) source attribution modeling. The CMAQ-ISAM ozone source attribution results for selected cities across the U.S. showed boundary conditions were the dominant contributor to the future year highest July maximum daily 8-hour average (MDA8) ozone concentrations. Point sources were generally larger contributors in the eastern U.S. than in the western U.S. The contributions of on-road mobile emissions were around 5 ppb at most of the cities selected for analysis. Off-road mobile source contributions were around 20 ppb or nearly 30%. Since boundary conditions play an important role in future year ozone levels, it is important to characterize future year boundary conditions accurately. The current implementation of ISAM in CMAQ 5.0.2 requires significant computing resources for ozone source attribution, making it difficult to conduct long-term simulations for large domains. The computing requirements for PM source attribution are even more onerous. CMAQ 5.2 was released after this study was completed, and does not include ISAM. If an efficient version of ISAM becomes available, it could be used in long-term ozone and PM2.5 studies. Implications: Ozone source attribution results provide useful information on important emission source contribution categories and provide some initial guidance on future emission reduction strategies. This study explains a new source apportionment technique, CMAQ-ISAM, and compares it to CAMx OSAT. The techniques have similar results: ozone’s highest source contributor is boundary conditions, followed by point sources, then off-road mobile sources. The current version of ISAM in CMAQ 5.0.2 requires significant computing resources for ozone source attribution, while the computing requirements for PM source attribution are even more onerous. CMAQ 5.2 was released after this study was completed, and does not include ISAM.     

Detecting diclofenac in livestock carcasses in India with an ELISA: a tool to prevent widespread vulture poisoning

Diclofenac, a non-steroidal anti-inflammatory drug (NSAID), has caused catastrophic vulture declines across the Indian sub-continent. Here, an indirect ELISA is used to detect and quantify diclofenac in 1251 liver samples from livestock carcasses collected across India between August 2007 and June 2008, one to two years after a ban on diclofenac manufacture and distribution for veterinary use was implemented. The ELISAs applicability was authenticated with independent data obtained using LC-ESI/MS. Of 1251 samples, 1150 (91.9%) were negative for diclofenac using both methods, and 60 (4.8%) were positive at 10-4348 and 10-4441 μg kg(-1) when analysed by ELISA and LC-ESI/MS, respectively. The residue level relationship in the 60 positive samples was highly significant (p < 0.001, r(2) = 0.644). Data suggest that this immunological assay could be used not only for cost effective sample screening, but also for residue level semi-quantification.     

A retrospective comparison of model-based forecasted PM2.5 concentrations with measurements

This study presents an assessment of the performance of the Community Multiscale Air Quality (CMAQ) photochemical model in forecasting daily PM2.5 (particulate matter < or = 2.5 microm in aerodynamic diameter) mass concentrations over most of the eastern United States for a 2-yr period from June 14, 2006 to June 13, 2008. Model predictions were compared with filter-based and continuous measurements of PM2.5 mass and species on a seasonal and regional basis. Results indicate an underprediction of PM2.5 mass in spring and summer, resulting from under-predictions in sulfate and total carbon concentrations. During winter, the model overpredicted mass concentrations, mostly at the urban sites in the northeastern United States because of overpredictions in unspeciated PM2.5 (suggesting possible overestimation of primary emissions) and sulfate. A comparison of observed and predicted diurnal profiles of PM2.5 mass at five sites in the domain showed significant discrepancies. Sulfate diurnal profiles agreed in shape across three sites in the southern portion of the domain but differed at two sites in the northern portion of the domain. Predicted organic carbon (OC) profiles were similar in shape to mass, suggesting that discrepancies in mass profiles probably resulted from the underprediction in OC. The diurnal profiles at a highly urbanized site in New York City suggested that the overpredictions at that site might be resulting from overpredictions during the morning and evening hours, displayed as sharp peaks in predicted profiles. An examination of the predicted planetary boundary layer (PBL) heights also showed possible issues in the modeling of PBL.     

Influence of clay on the adsorption of heavy metals like copper and cadmium on chitosan

The influence of clay on the adsorption of heavy metals like copper and cadmium on chitosan from simulated industrial wastewater is evaluated. Chitosan–clay blend with ratio of (1:1), (1:2), and (2:1) have been prepared, and these were used as membranes to remove copper and cadmium ions from synthetic industrial wastewater. The chemical parameters for quantities of adsorption of heavy metal contamination have been done, and the kinetics of adsorption has also been carried out. Clay provides enough absorbable sites to overcome mass transfer limitations. The number of absorbable sites for cadmium is more compared to copper, and thus the rate of recovery of cadmium is faster than copper, and the percentage removal of cadmium is more than copper at all times on clay over nylon 6. This difference indicates the influence of clay in the adsorption of heavy metals in comparison to synthetic polymer nylon 6. Rate constant for first-order kinetics of adsorption, k ₁, for copper and cadmium is less than that of clay, which clearly indicates that clay, which is a natural polymer, is more kinetically favored compared to synthetic polymer. The difference in the intraparticle diffusion in both the natural and synthetic polymer is not much, and it suggests that the particle diffusion mechanism is the same in both cases. Copper and cadmium recovery is parallel at all times. The percentage of removal of copper increased with an increase in pH from 3 to 5. In the case of cadmium containing wastewater, the maximum removal of metal occurred at pH 5. The uptake amount of Cu²⁺ ions on chitosan increased rapidly with increasing the contact time from 0 to 360 min and then reaches equilibrium after 360 min, and the equilibrium constant for copper and cadmium ions are more or less the same for the adsorption reaction. There are more adsorption sites for cadmium in the presence of clay and mass transfer limitation is avoided without resorting to rotation, which is the highlight of the present work. And more so, this is pronounced in the case of natural polymer compared to synthetic polymer.     

Power asymmetries and institutions: landscape conservation in central India

Understanding the importance of cross-sectoral implications of climate and socio-economic change in Scotland is essential for adaptation policy. This study explored the direct and indirect sectoral impacts of future change using the CLIMSAVE Integrated Assessment Platform. There is great spatial diversity in projected impacts across Scotland, and increasing uncertainty in the direction of change of impacts from the national to regional scale associated with climate uncertainty. Further uncertainty associated with socio-economic change results in 6 out of 13 indicators (artificial surfaces, biodiversity vulnerability, forest area, land-use intensity, irrigation usage and land-use diversity) with robust directions of change at the national scale and only three (artificial surfaces, forest area and irrigation usage) that are robust across all regions of Scotland. Complex interactions between socio-economic scenario assumptions (e.g. food imports, population and GDP), climatic suitability and agricultural productivity and profitability lead to significant national and regional changes in the distribution and extent of land cover types, with resultant cross-sectoral interactions with water, forestry and biodiversity. Consequently, stakeholders characterised robust adaptation policy options, within the CLIMSAVE participatory process, as those beneficial to society (and the country) in all scenarios, irrespective of the direction of change of the impacts. The integration in CLIMSAVE of a participatory scenario development process and an integrated participatory modelling framework has allowed the exploration of future uncertainty in a structured approach and better represented the importance of qualitative information and the social and institutional contexts within adaptation research.     

Magnetic mapping of fly-ash pollution and heavy metals from soil samples around a point source in a dry tropical environment

The Singrauli region in the southeastern part of Uttar Pradesh, India is one of the most polluted industrial sites of Asia. It encompasses 11 open cast coalmines and six thermal power stations that generate about 7,500 MW (about 10% of India’s installed generation capacity) electricity. Thermal power plants represent the main source of pollution in this region, emitting six million tonnes of fly-ash per annum. Fly-ash is deposited on soils over a large area surrounding thermal power plants. Fly-ashes have high surface concentrations of several toxic elements (heavy metals) and high atmospheric mobility. Fly ash is produced through high-temperature combustion of fossil fuel rich in ferromagnetic minerals. These contaminants can be identified using rock-magnetic methods. Magnetic susceptibility is directly linked to the concentration of ferromagnetic minerals, primarily high values of magnetite. In this study, magnetic susceptibility of top soil samples collected from surrounding areas of a bituminous-coal-fired power plant were measured to identify areas of high emission levels and to chart the spatial distribution of airborne solid particles. Sites close to the power plant have shown higher values of susceptibility that decreases with increasing distance from the source. A significant correlation between magnetic susceptibility and heavy metal content in soils is found. A comparison of the spatial distribution of magnetic susceptibility with heavy-metal concentrations in soil samples suggests that magnetic measurements can be used as a rapid and inexpensive method for proxy mapping of air borne pollution due to industrial activity.