Variation of radiation level and radionuclide enrichment in high background area

Significantly high radiation level and radionuclide concentration along Quilon beach area of coastal Kerala have been reported by several investigators. Detailed gamma radiation level survey was carried out using a portable scintillometer. Detailed studies on radionuclides concentration in different environmental matrices of high background areas were undertaken in the coastal areas of Karunagapalli, Kayankulam, Chavara, Neendakara and Kollam to study the distribution and enrichment of the radionuclides in the region. The absorbed gamma dose rates in air in high background area are in the range 43-17,400 nGyh⁻¹. Gamma radiation level is found to be maximum at a distance of 20 m from the sea waterline in all beaches. The soil samples collected from different locations were analysed for primordial radionuclides by gamma spectrometry. The activity of primordial radionuclides was determined for the different size fractions of soil to study the enrichment pattern. The highest activity of ²³²Th and ²²⁶Ra was found to be enriched in 125-63 μ size fraction. The preferential accumulation of ⁴⁰K was found in <63 μ fraction. The minimum ²³²Th activity was 30.2 Bq kg⁻¹, found in 1000-500 μ particle size fraction at Kollam and maximum activity of 3250.4 Bq kg⁻¹ was observed in grains of size 125-63 μ at Neendakara. The lowest ²²⁶Ra activity observed was 33.9 Bq kg⁻¹ at Neendakara in grains of size 1000-500 μ and the highest activity observed was 482.6 Bq kg⁻¹ in grains of size 125-63 μ in Neendakara. The highest ⁴⁰K activity found was 1923 Bq kg⁻¹ in grains of size <63 μ for a sample collected from Neendakara. A good correlation was observed between computed dose and measured dose in air. The correlation between ²³²Th and ²²⁶Ra was also moderately high. The results of these investigations are presented and discussed in this paper.     

Mobility of radium and trace metals in sediments of the Winterbeek: Application of sequential extraction and DGT techniques

For several decades, phosphate ores containing ²²⁶Ra as well as several trace metals have been processed in Belgium to produce calcium phosphate for use in cattle food. The waste water is discharged in two small rivers, the Laak and the Winterbeek.In this study, the levels of ²²⁶Ra and trace metals in surface water and sediments of the Winterbeek were investigated and the mobility of these compounds was assessed using DGT (Diffusive Gradient in Thin Films) and sequential extraction techniques.The concentrations of ²²⁶Ra and trace metals in water and sediment indicate a decreasing trend in inputs to the Winterbeek.The mobility of ²²⁶Ra, assessed by DGT, is related to the reductive mobilization of Fe. The sequential extraction technique shows that at some stations an important fraction of ²²⁶Ra is found to labile sediment phases.Diffusive ²²⁶Ra sediment fluxes, are however, relatively small and have only a minor contribution to the water column concentration of ²²⁶Ra.     

Resident Motivations and Willingness-to-Pay for Urban Biodiversity Conservation in Guangzhou (China)

The monetary assessment of biodiversity measures the welfare damages brought by biodiversity losses and the cost-benefit analysis of conservation projects in a socio-economic context. The contingent valuation method could include motivational factors to strengthen economic analysis of nature conservation. This study analyzed Guangzhou residents’ motivations and willingness-to-pay (WTP) for an urban biodiversity conservation program in the National Baiyun Mountain Scenic Area (BMSA). The peri-urban natural site, offering refuge to some endemic species, is under increasing development pressures for recreational and residential use. A questionnaire survey was conducted in the Guangzhou metropolitan area during June to October 2007. We interviewed face-to-face 720 stratified sampled households to probe residents’ attitudes towards the city’s environmental issues, motivations for urban nature conservation, and WTP for biodiversity conservation. Principal component analysis identified five motivational factors, including environmental benefit, ecological diversity, nature-culture interaction, landscape-recreation function, and intergenerational sustainability, which illustrated the general economic values of urban nature. Logistic regression was applied to predict the probability of people being willing to pay for the urban biodiversity conservation in BMSA. The significant predictors of WTP included household income and the factor nature-culture interaction. The median WTP estimated RMB149/household (about US$19.5/household) per year and an aggregate of RMB291 million (approximately US$19.5/household) per year and an aggregate of RMB291 million (approximately US38.2 million) annually to support the urban conservation project. Including public motivations into contingent valuation presents a promising approach to conduct cost-benefit analysis of public projects in China.     

Influence of operating conditions on nitrous oxide formation during nitritation and nitrification

Nitrous oxide (N₂O), a strong greenhouse gas, can be produced by ammonium-oxidizing bacteria (AOB) as a by-product of ammonium oxidation and can potentially be formed in all types of nitrification processes. However, partial nitritation has been reported to cause significantly higher N₂O emissions than complete nitrification. In the study presented here, the mechanisms and factors that drive N₂O formation by AOB were investigated with respect to different operational strategies to achieve nitrite accumulation base on combined evaluation of oxygen uptake rate (OUR) and N₂O formation rate. On the one hand, N₂O formation during partial nitritation and nitrification in a continuously stirred tank reactor (CSTR) with continuous aerobic conditions was observed. On the other hand, the effect of intermittent aeration on N₂O formation during nitrification was investigated. The presence of nitrite, the extend of sludge-specific ammonium loading, low oxygen concentration, and transition from aerobic to anoxic conditions significantly increased N₂O formation in this reactor independently from each other, indicating that different formation pathways, supposedly via nitrite or hydroxylamine, were active.     

A robust simulation–optimization modeling system for effluent trading—a case study of nonpoint source pollution control

In this study, a robust simulation–optimization modeling system (RSOMS) is developed for supporting agricultural nonpoint source (NPS) effluent trading planning. The RSOMS can enhance effluent trading through incorporation of a distributed simulation model and an optimization model within its framework. The modeling system not only can handle uncertainties expressed as probability density functions and interval values but also deal with the variability of the second-stage costs that are above the expected level as well as capture the notion of risk under high-variability situations. A case study is conducted for mitigating agricultural NPS pollution with an effluent trading program in Xiangxi watershed. Compared with non-trading policy, trading scheme can successfully mitigate agricultural NPS pollution with an increased system benefit. Through trading scheme, [213.7, 288.8]?×?10³ kg of TN and [11.8, 30.2]?×?10³ kg of TP emissions from cropped area can be cut down during the planning horizon. The results can help identify desired effluent trading schemes for water quality management with the tradeoff between the system benefit and reliability being balanced and risk aversion being considered.     

Fuel efficiency improvement of a dual-fuel engine fuelled with Honge oil methyl ester (HOME)–bioethanol and producer gas

Renewable and alternative fuels have numerous advantages compared with fossil fuels as they are renewable and biodegradable and provide food and energy security and foreign exchange savings besides addressing environmental concerns and socio-economic issues (Yaliwal et al. 2013. International Journal of Sustainable Engineering, doi:10.1080/19397038.2013.801530. Zhu et al. 2011a, Applied Thermal Engineering 31 (14–15): 2271–2278; Zhu et al. 2011b, Fuel 90: 1743-1750; Banapurmath, Tewari, and Hosmath 2008, Renewable Energy 33: 2007-2018; Banapurmath 2009, “Performance, Combustion and Emission Characteristics of a Single Cylinder Direct Injection CI Engine Operated on Dual Fuel Mode Using Honge Oil and Producer Gas.” PhD thesis, 1–195; Banapurmath et al. 2011, Waste and Biomass Valorization 2: 1–11). In this context, the main objective of the present work is to study methods of biofuel production such as Honge oil methyl ester (HOME) using a conventional transesterification process and bioethanol from the Calliandra calothyrsus shrub using a new pretreatment method known as hydrothermal explosion. Further, experimental investigations were carried out on a single-cylinder, four-stroke, direct-injection stationary diesel engine operating in a dual-fuel mode using HOME, bioethanol and producer gas combinations to determine its performance, combustion and emission characteristics. The performance of the dual-fuel engine was analyzed at optimized engine conditions. HOME-Bioethanol (BE) blends such as HOME+ 5% bioethanol (BE5), HOME+ 10% bioethanol (BE10) and HOME+ 15% bioethanol (BE15) were prepared by adding bioethanol to HOME (on volume basis) in different proportions ranging from 5 to 15% with an increment of 5%. In this present work, the effect of different BE blends on the performance of producer gas fuelled dual fuel engine was studied. Experimental investigation on dual fuel engine using BE5-Producer gas operation resulted in up to 4–9% increased brake thermal efficiency with decreased hydrocarbon (HC), carbon monoxide (CO) and marginally increased nitric oxide (NOx) emission levels compared to HOME-Producer gas, BE10-producer gas and BE15-producer gas mode of operation. However, it was observed that, the overall performance of BE-producer gas operation was found to be lower compared to diesel-producer gas operation.     

Transmissometer Measurement of Participate Emissions from a Jet Engine Test Facility

The body of information presented in this paper is directed toward those individuals involved with handling hazardous materials, whether in actual use of such chemicals, or in monitoring atmospheric emissions. Although specifically relating experience in the design and testing of phosgene emission control equipment, it attempts to establish general guidelines for effectively dealing with emissions of hazardous materials. An approach for handling chemical pollutants having no established air quality emission standards is developed. The paper presents a technique for establishing process emissions at acceptably low levels to insure the health and safety of the general population as well as that of the process workers themselves. Methods, suitable for measuring phosgene at these low levels, have been investigated, and problems associated with such an investigation are discussed. While complete theoretical scrubber design criteria are beyond the scope of this paper, many of the "real world" problems which affected scrubber performance are presented. Finally, the practical aspects of process emissions control are illustrated by actual results from the system test.     

Trends and Relationships of O3, NOx and HC in the South Coast Air Basin of California

A basin-wide air quality trend analysis for the South Coast Air Basin of California is conducted for hydrocarbons (HC), NO_x, O₃ and CO using multi-station composite daily maximum-hour average ambient concentrations for the third quarter (July, August and September) from 1968 to 1985. Emissions and air quality trends are compared for the period 1968-1984. Ambient HC and NOX trends are somewhat different from estimated emission trends of HC and NO_x, while a definite, downward trend of ambient CO is consistent with vehicular emission control measures. Basin-wide ambient HC, NO_x and O₃ appear to show downward trends for the period 1970-1985, but because of high fluctuations it is difficult to delineate trends for shorter periods. The meteorology (850 mb temperature)-adjusted O₃ shows a more consistent downward trend than does unadjusted O₃. Polynomial and multiplicative regression models for basin-wide empirical O₃-HC-NO_x relationships Indicate that the O₃ variation is explained largely by the meteorological variable (850 mb temperature) although model estimations are improved by adding HC and NO_x concentration terms.