A detailed kinetic investigation on the effects of hydrogen enrichment on the performance of gas-fueled SI engine

This study investigates the effects of hydrogen enrichment on formation of pollutants and greenhouse gases in gas-fueled spark ignition engines. To this end, a previously validated detailed mechanism is embedded with a comprehensive one-dimensional engine model and the results are verified with experimental observations at different compression ratios and engine loads. The simulations are then performed for different mixtures of hydrogen and natural gas. The results indicate that adding hydrogen increases the cylinder peak pressure at different loads and compression ratios, despite the fact that reduces the amount of carbon monoxide, carbon dioxide, and methane in all the conditions.     

Lung function decrement with arsenic exposure to drinking groundwater along River Indus: a comparative cross-sectional study

This study was designed to determine the association between chronic arsenic exposure through drinking groundwater and decrement in lung function, particularly among individuals who do not have signs of arsenic lesions, among an adult population. This was a comparative cross-sectional study conducted during the months of January to March 2009. One hundred participants ≥15 years of age in each group, i.e. exposed (≥100 μg/l) and unexposed (≤10 μg/l) to arsenic, determined by testing drinking water samples (using portable kits), were compared for effects on lung function using spirometry. A structured and validated questionnaire was administered. Examination for arsenic skin lesions was also done. There was a decline in the mean adjusted FEV1 of 154.3 ml (95% CI: −324.7, 16.0; p = 0.076), in mean adjusted FVC of 221.9 ml (95% CI: −419.5, −24.3; p = 0.028), and in FEV1/FVC ratio of 2.0 (95% CI: −25.3, 29.4; p = 0.884) among participants who were exposed to arsenic compared to those unexposed. A separate model comprising a total of 160 participants, 60 exposed to arsenic concentrations ≥250 μg/l and 100 unexposed at arsenic concentrations of ≤10 μg/l, showed a decrement in mean adjusted FEV1 of 226.4 ml (95% CI: −430.4, −22.4; p = 0.030), in mean adjusted FVC of 354.8 ml (95% CI: −583.6, −126.0; p = 0.003), and in FEV1/FVC ratio of 9.9 (95% CI: −21.8, 41.6; p = 0.539) among participants who were exposed to arsenic in drinking groundwater. This study demonstrated that decrement in lung function is associated with chronic exposure to arsenic in drinking groundwater, occurring independently, and even before any manifestation, of arsenic skin lesions or respiratory symptoms. The study also demonstrated a dose-response effect of arsenic exposure and lung function decrement.     

Geochemical characterisation of pyrite oxidation and environmental problems related to release and transport of metals from a coal washing low-grade waste dump, Shahrood, northeast Iran

Pyrite oxidation and release of the oxidation products from a low-grade coal waste dump to stream, groundwater and soil was investigated by geochemical and hydrogeochemical techniques at Alborz Sharghi coal washing plant, Shahrood, northeast Iran. Hydrogeochemical analysis of water samples indicates that the metal concentrations in the stream waters were low. Moreover, the pH of the water showed no considerable change. The analysis of the stream water samples shows that except the physical changes, pyrite oxidation process within the coal washing waste dump has not affected the quality of the stream water. Water type was determined to be calcium sulphate. The results of the analysis of groundwater samples indicate that the pH varies from 7.41 to 7.51. The concentrations of the toxic metals were low. The concentration of SO4 is slightly above than its standard concentration in potable water. It seems that the groundwater less affected by the coal washing operation in the study area. Geochemical analysis of the sediment samples shows that Fe concentration decreases gradually downstream the waste dump with pH rising. SO(4) decreases rapidly downstream direction. Copper, Zn and Co concentrations decrease with distance from the waste dump due to a dilution effect by the mixing of uncontaminated sediments. These elements, in particular, Zn are considerably elevated in sediment sample collected at the nearest distance to the waste dump. There is no doubt that such investigations can help to develop an appropriate water remediation plan.     

A novel wet-scrubbing process using Fe(VI) for simultaneous removal of SO2 and NO

The objective of this work was to develop a novel wet-scrubbing process using Fe(VI) for the simultaneous removal of gaseous NO and SO(2). The oxidation of SO(2) and NO with Fe(VI) was studied in aqueous solution at alkaline pH (9.0-11.0). A stoichiometric molar ratio for NO and SO(2) oxidation with Fe(VI) was determined to be nearly 3.0. Sulfate and nitrate was identified as final products by ion chromatography from the reaction at pH 9.0-11.0. The feasibility of simultaneous removal of multiple gas pollutants with the continuous feeding of ferrate in lab-scale was investigated from the view of industrial application. It was found that the removal efficiency of NO and SO(2) was enhanced with the increase of Fe(VI) concentration, more than 90% NO removal efficiency and 100% SO(2) removal efficiency were achieved by wet-scrubbing process using Fe(VI) at room temperature and ambient atmosphere. The results demonstrate that Fe(VI) could be an effective wet-scrubbing agent for the simultaneous removal of NO and SO(2).     

The distribution of triclosan and methyl-triclosan in marine sediments of Barker Inlet, South Australia

In this work, we investigated the transport and burial of triclosan and its methylated derivative, in surface sediments near the mouth of Barker Inlet in South Australia. The most likely source of this commonly used bactericide to the area is a wastewater outfall discharging at the confluence of the inlet with marine waters. Triclosan was detected in all samples, at concentrations (5-27 μg kg(-1)) comparable to values found in other surface sediments under the influence of marine wastewater outfalls. Its dispersal was closely associated with fine and organic-rich fractions of the sediments. Methyl-triclosan was detected in approximately half of the samples at concentrations <11 μg kg(-1). The occurrence of this compound was linked to both wastewater discharges and biological methylation of the parent compound. Wastewater-borne methyl-triclosan had a smaller spatial footprint than triclosan and was mostly deposited in close proximity to the outfall. In situ methylation of triclosan likely occurs at deeper depositional sites, whereas the absence of methyl-triclosan from shallower sediments was potentially explained by photodegradation of the parent compound. Based on partition equilibrium, a concentration of triclosan in the order of 1 μg L(-1) was estimated in sediment porewaters, a value lower than the threshold reported for harmful effects to occur in the couple of species of marine phytoplankton investigated to date. Methyl-triclosan presents a greater potential for bioaccumulation than triclosan, but the implications of its occurrence to aquatic ecosystem health are difficult to predict given the lack of ecotoxicological data in the current literature.     

Quantifying the Effects of Forest Management Strategies on the Production of Forest Values: Timber,Carbon, Oxygen,Water, and Soil

Forest management practices alter forest structure quantified with ecosystem characteristics and values. In this paper, we utilized a forest management simulation model to assess the effects of three forest management strategies focusing on timber production, carbon sequestration, oxygen production, soil erosion, and water production of a forest management unit in Turkey. A forest simulation model “ETÇAPSimülasyon” was developed and used to project forest ecosystem development over 100 years under three forest management policies of timber-oriented forest management (TFM), multipurpose forest management (MFM), and no intervention (NI). The results showed that TFM strategy produced more timber and its net present value than MFM and NI strategies did. The amount of carbon sequestration and oxygen production potential was also found to be the highest with TFM strategy than with the MFM and NI strategies. Compared with the other strategies, however, NI strategy produced the highest amount of water production and soil losses over the planning horizon. The effects of a forest management strategy depend mainly on the initial forest structure, the rate of development and the level of forest management interventions. Therefore, forest dynamics under various management strategies should be explained before the final management decision. Understanding long-term effects of any management strategies on forest structure will provide the basis for better reaching the management objectives.     

Determination of <Superscript>90</Superscript>Sr in milk and milk powder in Tehran and estimation of annual effective dose

Thirty-eight different milk and milk powder samples from Tehran-Iran were collected and analyzed for ⁹⁰Sr activity using a method in which the daughter product of ⁹⁰Sr decay (⁹⁰Y) was extracted by tributyl phosphate from ashed milk. ⁹⁰Y was then back extracted with water, and oxalate was precipitated . Following the sample analyzing, beta counting was performed with an ultralow-level liquid scintillation spectrometer. The quality control and assurance of the method were obtained by standard samples prepared with an IAEA-certified reference material. The mean determined ⁹⁰Sr activity concentration in the analyzed milk and milk powder (0.225 ± 0.042 and 0.216 ± 0.024 Bq kg⁻¹, respectively) showed that the radioactivity concentration in our samples was too low to induce biological hazards. These data can provide useful information of the background level of contamination, which in turn can be used in the following environmental monitoring programs.