Treatment of PAHs in contaminated soil by extraction with aqueous DNA followed by biodegradation with a pure culture of Sphingomonas sp

The biodegradation of polycyclic aromatic hydrocarbons (PAHs) in aqueous deoxyribonucleic acid (DNA) solution from contaminated soil washing was investigated. Initial data with a model effluent consisting of anthracene, phenanthrene, pyrene and benzo[a]pyrene that were individually dissolved in 1% aqueous DNA solution confirmed their positive degradation by Sphingomonas sp. at around 10(8)CFU mL(-1) initial cell loading. For anthracene and phenanthrene, complete removal was achieved within 1h treatment. Degradation of pyrene and benzo[a]pyrene took a relatively longer time of a few days and weeks, respectively. DNA-dissolved PAHs were also degraded relatively faster than PAH crystals in aqueous medium to suggest that the binding of the PAHs in the polymer does not pose serious constraint to bacterial uptake. The DNA was stable against the PAH-degrading bacteria. Parallel experiments with actual DNA solutions obtained during pyrene extraction from an artificially spiked soil also showed similar results. Close to 100% pyrene degradation was achieved after 1d treatment. With its chemical stability, the cell-treated DNA was re-used up to four cycles without a considerable decline in extraction performance.     

Assessing the probability of land submergence for lowland rice cultivation in Africa using satellite imagery and geospatial data

Sub-Saharan African countries are being strongly urged to enhance their rice production, because their rice consumption and importation rates have been rapidly increasing in recent years. Areas planted to rice in Africa are classified agro-ecologically into rainfed upland, rainfed lowland, and irrigated. Rainfed lowland includes extensive areas of unexploited land that has great potential for the promotion of rice growing. For the unexploited rainfed lowlands of Ghana, we have been studying the development of low-cost rice-farming systems that require no large-scale irrigation or land reclamation. For such systems, it is important to select suitable areas where water for rice farming can be obtained naturally; floodwaters offer promise for this purpose. Delineation and mapping of floodwater prone areas suitable for rice production is important for successful utilization of this land resource. Here, we propose a method of assessing flood probability from submergence frequency, as estimated from satellite imagery and geospatial data. ALOS/PALSAR images acquired in May, June, August, and September 2010 were used to classify land and water, and then a submerged-area map was produced. From the results, we were able to accurately detect non-submerged areas and submerged areas with water depths of at least 3?cm. The number of times classified into submerged area was defined as submergence frequency, and it was approximated by distance from reservoirs representing White Volta River, ponds, and swamps. In addition, flood extent derived from reservoirs was simulated using digital elevation model (DEM). Finally, a flood probability assessment map was produced by integration of the estimated submergence frequency and flood extent simulation. The results of a comparison of soil moisture data measured at 69 points in the field and the NDVIs computed by ALOS/AVNIR showed that areas with high potential for flooding retained high levels of soil moisture and were more likely to show less deterioration of vegetation in the dry season. The validation of these results confirmed the adequacy of the flood probability assessment method.     

Formation of chloroform and carbon tetrachloride in foods treated with sodium hypochlorite

The formation of chloroform and carbon tetrachloride during the treatment of fresh vegetable homogenate with sodium hypochlorite was studied.When a n-hexane extract of the reaction mixture of fresh vegetables and sodium hypochlorite was analysed by gas chromatography, chloroform and carbon tetrachloride were detected, and many unidentified peaks were also observed. The formation conditions of chloroform and carbon tetrachloride were studied. The mechanism of chloroform formation may be different from that of carbon tetrachloride according to the study of pH on the formation of both compounds. The formation of chloroform is much greater than that of carbon tetrachoride.     

Influence of chemical characteristics of humic substances on the partition coefficient of a chlorinated dioxin

The partition coefficients (Koc) of 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin (HpCDD) with respect to a variety of humic substances (HSs) were evaluated by a method involving solid-phase microextraction and gas chromatography-electron capture detection. The log Koc values for each of the HS samples were in the range of 6.4-7.7. The log Koc values for HAs from tropical peat, brown forest and ando soils were in the range of 7.3-7.6, similar to the calculated value for the octanol-water partition coefficient (log Koc=7.56). In contrast, the log Koc values for FAs and peat HAs were 0.5-1 unit lower than the calculated value. The parameters for the polarity of HSs, as calculated from (N+O)/C, O/C atomic ratios and the carboxyl group content, were numerically similar related to the log Koc for HpCDD. These results show that the Koc values for HpCDD are significantly influenced by the polarity of HSs.     

Development of a new antifouling method for a marine cooling water system

Variations in meristic characters occur within and between samples of milkfish Chanos chanos (Forsskal) collected on June 1977 from five localities in Philippine waters. The unbranched anal and ventral fin rays are the most plastic, and vertebral number is the most stable of nine meristic characters examined. The number of ventral fin rays is the only meristic feature which differed consistently enough to suggest distinct population groups: South China Sea, comprising samples from Ilocos and Panay Island; Pacific Ocean from Bicol; and Celebes Sea, from Zamboanga and Davao. A discriminant analysis which incorporated generalized distance (Mahanalobis D²) and percent overlap of a reduced set of characters indicated several morphometric subgroups of milkfish in Philippine waters, although geographic subgroups were not clearly demonstrated.SEAFDEC Contribution No. 218     

Relative importance and interactive effects of photosynthesis and food in two solar-powered sea slugs

Sacoglossans use chloroplasts taken from algal food for photosynthesis (kleptoplasty), but the adaptive significance of this phenomenon remains unclear. Two con-generic sacoglossans (Elysia trisinuata and E. atroviridis) were collected in 2009–2011 from Shirahama (33.69°N, 135.34°E) and Mukaishima (34.37°N, 133.22°E), Japan, respectively. They were individually maintained for 16 days under four experimental conditions (combination of light/dark and with/without food), and their survival rate and relative (=final/initial) weights were measured. Both light and food had positive effects on the survival in E. trisinuata, whereas no positive effects of light or food on survival were detected in E. atroviridis. Both light and food had positive effects on relative weights in both species, but light had smaller effects than food. A significant interaction term between light and food was detected in E. trisinuata (but not in E. atroviridis) in that only the presence of both resulted in weight gains. This result suggests that E. trisinuata can obtain sufficient additional energy from photosynthesis for sustaining growth when fresh chloroplasts are continuously supplied from algal food. In addition, fluorescence yield measurements showed that unfed individuals of both E. trisinuata and E. atroviridis lost photosynthetic activity soon (<4 and 4–8 days, respectively). In conclusion, photosynthesis may function to obtain supplementary nutrition for sustaining growth when food is available in sacoglossans with short-term functional kleptoplasty.     

A probabilistic economic model and sensitivity analysis of fuel-oil production from plastic waste

Journal of Material Cycles and Waste Management - Pyrolysis of plastic waste has been studied for many years, but there are only a few commercial plants in the world. A probabilistic economic model...     

Improvement of an efficient separation method for chemicals in diesel exhaust particles: analysis for nitrophenols

GOAL, SCOPE, AND BACKGROUND: Diesel exhaust is believed to consist of thousands of organic constituents and is a major cause of urban pollution. We recently reported that a systematic separation procedure involving successive solvent extractions, followed by repeated column chromatography, resulted in the isolation of vasodilatory active nitrophenols. These findings indicated that the estimation of the amount of nitrophenols in the environment is important to evaluate their effect on human health. The isolation procedure, however, involved successive solvent extractions followed by tedious, repeated chromatography, resulting in poor fractionation and in a significant loss of accuracy and reliability. Therefore, it was crucial to develop an alternative, efficient, and reliable analytical method. Here, we describe a facile and efficient acid-base extraction procedure for the analysis of nitrophenols. MATERIALS AND METHODS: Diesel exhaust particles (DEP) were collected from the exhaust of a 4JB1-type engine (ISUZU Automobile Co., Tokyo, Japan). Gas chromatography-mass spectrometry (GC-MS) analysis was performed with a GCMS-QP2010 instrument (Shimadzu, Kyoto, Japan). RESULTS: A solution of DEP in 1-butanol was extracted with aqueous NaOH to afford a nitrophenol-rich oily extract. The resulting oil was methylated with trimethylsilyldiazomethane and subsequently subjected to GC-MS analysis, revealing that 4-nitrophenol, 3-methyl-4-nitrophenol, 2-methyl-4-nitrophenol, and 4-nitro-3-phenylphenol were present in significantly higher concentrations than those reported previously. DISCUSSION: Simple acid-base extraction followed by the direct analysis of the resulting extract by GC-MS gave only broad peaks of nitrophenols with a poor detection limit, while the GC-MS analysis of the sample pretreated with (trimethylsilyl)diazomethane gave satisfactorily clear chromatograms with sharp peaks and with a significantly lowered detection limit (0.5 ng/ml, approximately 100 times). CONCLUSION: The present method involving an acid-base extraction, in situ derivatization, and GC-MS analysis has shown to be a simple, efficient, and reliable method for the isolation and identification of the chemical substances in DEP.     

Decomposition of trichloroethylene and 2,4-dichlorophenol by ozonation in several organic solvents

The effects of chemical characteristics of organic solvents on the decomposition rate constants of undissociative trichloroethylene (TCE) and dissociative 2,4-dichlorophenol (2,4-DCP) by ozonation were studied. The TCE and 2,4-DCP decomposition by ozonation in organic solvents followed to the first-order reaction kinetics with respect to TCE or 2,4-DCP concentration. The orders of the rate constants among organic solvents for undissociative TCE and dissociative 2,4-DCP were different indicating that the ozonation rates for undissociative and dissociative compounds were dependent on the chemical property of organic solvent. The decomposition of undissociative TCE by ozonation was a simple electrophilic reaction, which was dependent on acceptor number (AN) of the solvent. On the other hand, the decomposition of dissociative 2,4-DCP was dependent on by the dissociation of the compounds and would be dependent on donor number (DN) of the solvent. Finally, TCE in acetic acid was transformed to chlorinated intermediates and chloride ion and then these intermediates were continuously oxidized to chlorine gas.