Comparative studies on performance of solar towers with variable scale ratios

Environmental Science and Pollution Research - Improvements in the geometry of solar towers are explained in this study. Both computational and experimental studies are carried out. Three different...     

Experimental investigation of density,viscosity, and surface tension of aqueous tetrabutylammonium-based ionic liquids

Environmental Science and Pollution Research - The physical properties such as density, dynamic viscosity, and surface tension of aqueous tetrabutylammonium-based ionic liquids were measured...     

Environmental Monitoring Of Remedial Dredging At The New Bedford Harbor, Ma, Superfund Site

New Bedford Harbor (NBH), MA, is a Superfund site because of high polychlorinated biphenyl (PCB) concentrations in the sediment. From April 1994 to September 1995, a remedial dredging operation (termed the “Hot Spot”) removed the most contaminated sediments (PCB concentrations greater than 4000μg/g) from the upper harbor. During remediation, a monitoring program assessed the potential environmental impacts to NBH and adjacent Buzzards Bay. The monitoring program was developed with input from federal, state, and local authorities. Site-specific decision criteria were established to assess net PCB transport, water column toxicity, and PCB bioaccumulation in blue and ribbed mussels (Mytilus edulis and Geukensia demissa, respectively). The remediation was completed without exceeding PCB net transport or acute toxicity effects specified in the decision criteria. In addition, PCB bioaccumulation in mussels during this time period was not significantly greater than pre- or post-operational measurements. The results indicated that approximately 14000 cubic yards of highly PCB contaminated sediment were permanently removed with minimal environmental effects. The lessons learned during this operation, as well as previous pilot studies at the site, will be used to make full-scale remedial efforts in NBH more efficient and environmentally protective.     

Extraction of organic contaminants from marine sediments and tissues using microwave energy.

In this study, we compared microwave solvent extraction (MSE) to conventional methods for extracting organic contaminants from marine sediments and tissues with high and varying moisture content. The organic contaminants measured were polychlorinated biphenyl (PCB) congeners, chlorinated pesticides, and polycyclic aromatic hydrocarbons (PAHs). Initial experiments were conducted on dry standard reference materials (SRMs) and field collected marine sediments. Moisture content in samples greatly influenced the recovery of the analytes of interest. When wet sediments were included in a sample batch, low recoveries were often encountered in other samples in the batch, including the dry SRM. Experiments were conducted to test the effect of standardizing the moisture content in all samples in a batch prior to extraction. SRM1941a (marine sediment). SRM1974a (mussel tissue), as well as QA96SED6 (marine sediment), and QA96TIS7 (marine tissue), both from 1996 NIST Intercalibration Exercise were extracted using microwave and conventional methods. Moisture levels were adjusted in SRMs to match those of marine sediment and tissue samples before microwave extraction. The results demonstrated that it is crucial to standardize the moisture content in all samples, including dry reference material to ensure good recovery of organic contaminants. MSE yielded equivalent or superior recoveries compared to conventional methods for the majority of the compounds evaluated. The advantages of MSE over conventional methods are reduced solvent usage, higher sample throughput and the elimination of halogenated solvent usage.     

Effect of hydrogen addition on performance,emission, and combustion characteristics of Deccan hemp oil and its methyl ester–fuelled CI engine

Environmental Science and Pollution Research - A vegetable oil–fueled diesel engine operation is characterized by low brake thermal efficiency and relatively high smoke emission. Conversion...     

Retrospective monitoring of persistent organic pollutants,including PCBs,PBDEs, and polycyclic musks in blue mussels (Mytilus edulis) and sediments from New Bedford Harbor,Massachusetts, USA: 1991–2005

Blue mussels (Mytilus edulis) and sediments collected from 1991 to 2005 from New Bedford Harbor (NBH), MA, were analyzed for two polycyclic musks (HHCB or Galaxolide® and AHTN or Tonalide®), polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs). HHCB and AHTN were found in mussel tissues at mean concentrations of 836 and 376 ng/g lipid weight (lw), respectively, which were two- to seven-fold higher than those found at a reference site. Mean concentrations of HHCB and AHTN in NBH sediments were 12 and 6.3 ng/g dry weight (dw), respectively. Four- and five-ringed PAHs, such as phenanthrene, anthracene, fluoranthene, and pyrene, collectively accounted for 61 % of the ∑PAHs concentrations in mussels from NBH. Mean ΣPCB concentrations in mussels from upper and lower NBH were 942 and 182 μg/g lw, respectively, and were dominated by tetra- and penta-chlorobiphenyl congeners, collectively accounting for 61 % of the ΣPCB concentrations. The mean concentration of ∑PBDEs in mussels from NBH was 277 ng/g lw, and no significant difference existed in the concentrations between upper and lower NBH. DDTs were the major OCP found in mussels, found at a mean concentration of 778 ng/g lw. The concentrations of HHCB, AHTN, ΣPBDEs, ΣPAHs, and DDTs in mussels decreased significantly (r ²?≥?0.56, p?≤?0.052) from 1991 to 2005. The concentrations of PCBs and chlordanes did not exhibit a decreasing trend in mussel tissues (r ²?<?0.50; p?>?0.076) from 1991 to 2005. Based on the temporal trends in the concentrations of HHCB, AHTN, ∑PAHs, and ∑PBDEs found in mussels from NBH, it was estimated that between 5.5 and 12 years were required for the concentrations of these compounds to decrease by half (i.e., environmental halving time) of the levels found in 1991.     

Air quality and respiratory health in Delhi

Delhi is an instructive location for studying the impact of air pollution since it is a rapidly expanding centre of government, trade commerce and industry. We have made an attempt to (1) determine the association between environmental pollution and respiratory morbidity in Delhi for the period 1998–2004, (2) assess the impact on hospital admission of the implementation of recent governmental regulations and (3) calculate the relative risk of hospitalization due to respiratory ailments caused by air pollutants. Seven hospitals from different parts of Delhi were selected. The pollution profiles of these areas were assessed and subsequently Poisson regression model was performed for the patient population. There was a remarkable decrease in monthly average concentration of sulphur dioxide (from 17.9 to 11.1 μg m⁻³) and increase in monthly average concentration of nitrogen dioxide (from 34.2 to 49.1 μg m⁻³) after the newly introduced regulations. Particulates were observed to have marginal fall in their concentration but still remained above the permissible limits. Gaseous pollutants, in spite of being at a level lower than the permissible level, showed more consistent significant association with respiratory admissions. The relative risks of hospitalization due to respiratory diseases were in the range of 1.07–2.82 in residential cum commercial areas. Comparative study of pre and post new stringent governmental regulation showed significant positive association of NO₂ with respiratory disorders in southern (RR: 1.10; CI: 1.09–1.12) and northern regions (RR: 1.33; CI: 1.27–1.39), both mixed use areas. In spite of the improvement in the air quality, the associated health effects were found to be substantial.     

Ammonia volatilization loss from surface applied livestock manure

Ammonia (NH₃) emission from livestock manures used in agriculture reduces N uptake by crops and negatively impacts air quality. This laboratory study was conducted to evaluate NH₃emission from different livestock manures applied to two soils: Candler fins sand (CFS; light-textured soil, pH 6.8 and field capacity soil water content of 70 g kg^{? 1}) from Lake Alfred, Florida and Ogeechee loamy sand (OLS; medium-textured soil, pH 5.2 and field capacity soil water content of 140 g kg^{? 1}) from Savannah, Georgia. Poultry litter (PL) collected from a poultry farm near Douglas, Georgia, and fresh solid separate of swine manure (SM) collected from a farm near Clinton, North Carolina were used. Each of the soil was weighed in 100 g sub samples and amended with either PL or SM at rates equivalent to either 0, 2.24, 5.60, 11.20, or 22.40 Mg ha^{? 1} in 1L Mason jars and incubated in the laboratory at field capacity soil water content for 19 days to monitor NH₃ volatilization. Results indicated a greater NH₃ loss from soils amended with SM compared to that with PL. The cumulative NH₃volatilization loss over 19 days ranged from 4 to 27% and 14 to 32% of total N applied as PL and SM, respectively. Volatilization of NH₃ was greater from light-textured CFS than that from medium-textured OLS. Volatilization loss increased with increasing rates of manure application. Ammonia volatilization was lower at night time than that during the day time. Differences in major factors such as soil water content, temperature, soil type and live stock manure type influenced the diurnal variation in volatilization loss of NH₃ from soils. A significant portion (> 50%) of cumulative NH₃ emission over 19 d occurred during the first 5–7 d following the application of livestock manures. Results of this study demonstrate that application of low rates of livestock manure (≤ 5.60 Mg ha^{? 1}) is recommended to minimize NH₃ emissions.