Polychlorinated biphenyl (PCB) congeners and chlorinated pesticides in a cod liver oil reference material

A cod liver oil reference material, Standard Reference Material (SRM) 1588, which was issued by the National Institute of Standards and Technology (NIST) in 1989, has certified concentrations for five polychlorinated biphenyl (PCB) congeners and ten chlorinated pesticides. Recently, this SRM has been extensively characterized by additional analyses at NIST and by analyses at the Canadian Wildlife Service (CWS) where the SRM was used as a control sample during routine analyses of wildlife tissue specimens. In this paper the results from NIST and CWS are compared and the concentrations for over 40 PCB congeners and 20 chlorinated hydrocarbons are reported.     

Morphology, molecular phylogeny and photosynthetic activity of the sacoglossan mollusc, Elysia nigrocapitata, from Korea

The morphology, external coloration as well as the life span of a kleptoplastic mollusc, Elysia nigrocapitata, was affected by its algal diet. Among algal diets, Chaetomorpha moniligera was the best for growth but not for animal longevity. TEM studies showed several distinctive layers composed of different cell types in sectioned parapodia. The chloroplast-containing digestive cells were located beneath the layer of vacuolated cells. The digestive cells contained 10–15 chloroplasts, in varying states of intactness, and several nuclei. Chloroplasts were not enclosed by any membranous structure in the host cytosol. Chlorophyll a fluorometry showed that the photosynthetic activity of kleptoplasts in E. nigrocapitata could be maintained for a long time only when animals were kept in the dark. The photosynthetic activity of kleptoplasts lasted 3–4 days when the animals were exposed to continuous illumination of 200 μmol photons m^?2 s^?1. These results suggested that the contribution of kleptoplasts to the survival of the animals might be minimal if the chloroplasts are not sequestered continuously. Cox I, 16S rDNA, and 28S rDNA sequence data have been obtained in order to phylogenetically place the new species of Elysia found in Korea.     

Optimization for solidification of low-level-radioactive resin using Taguchi analysis

Solidification of low-level-radioactive (LLW) resin was optimized using Taguchi analytical methodology. The ingredients in LLW mortar which caused the solidification of cement were evaluated through consecutive measurements of the effects of various concentrations of ingredients. Samples selected according to Taguchi's method were separated into 18 different categories and measured at the 7th, 21st, and 28th day after fabrication on developing effects. Evaluations of the various samples focused on whether the compressive and bending strength fulfilled the special criteria of the Taiwan Power Company (TPC). Similar results indicated that both furnace slag and fly ash were the dominant material resulting from the solidification of LLW mortar. The superior combination was obtained as furnace slag 24 wt.%, fly ash 24 wt.%, and cement 8 wt.% to mix 24 wt.% of resin with 20 wt.% of water, to fulfill the contemporary requirements of TPC.     

Performance of a full-scale biofilm system retrofitted with an upflow multilayer bioreactor as a preanoxic reactor for advanced wastewater treatment

To enhance nitrogen removal in an existing microbial contact oxidation (MCO) system with a treatment capacity of 900 m3/d, an upflow multilayer bioreactor (UMBR) was chosen as a preanoxic reactor for the removal of organic matter and nitrate. The removal performance of the retrofitted plant was evaluated during the startup phase at a low temperature in winter. The high removal (>80%) of organic matter and suspended solids in the UMBR provided stable nitrification conditions in the MCO system, as a result of the substantial reduction in organic matter and solids loaded onto the MCO system. This treatment system showed a stable nitrogen removal efficiency of 75.3%, even in the low temperature range 7 to 10 degrees C. Phosphorus was completely removed by chemical precipitation. Production rates of excess sludge, as a function of the loads of influent flowrate and biological oxygen demand (BOD), were 0.022 kg dry solid/m3 wastewater and 0.132 kg dry solid/kg BOD.     

Factors dominating stratification cycle and seasonal water quality variation in a Korean estuarine reservoir

A comprehensive monitoring program was conducted during 2005-2007 to investigate seasonal variations of hydrologic stability and water quality in the Yeongsan Reservoir (YSR), located at the downstream end of the Yeongsan River, Korea. A principal component analysis (PCA) was performed to identify factors dominating the seasonal water quality variation from a large suite of measured data--11 physico-chemical parameters from 48 sampling sites. The results showed that three principal components explained approximately 62% of spatio-seasonal water quality variation, which are related to stratifications, pollutant loadings and resultant eutrophication, and the advective mixing process during the episodic rainfall-runoff events. A comparison was then made between YSR and an upstream freshwater reservoir (Damyang Reservoir, DYR) in the same river basin during an autumn season. It was found that the saline stratification and pollutant input from the upstream contributed to greater concentrations of nutrients and organic matter in YSR compared to DYR. In YSR, saline stratification in combination with thermal stratification was a dominant cause of the longer period (for two consecutive seasons) of hypoxic conditions at the reservoir bottom. The results presented here will help better understand the season- and geography-dependent characteristics of reservoir water quality in Asian Monsoon climate regions such as Korea.     

Water Quality and Pollution in the Hunchun Basin, China

Chemical properties and pollution of water resources were studied in the Hunchun basin, which is located in northeast China and borders directly North Korea and Russia along the Tumen river. Water quality was characterised according to its major constituents and geological features. Ground waters could generally be grouped into (Ca+Mg)-HCO₃ type and (Ca+Mg)-(SO₃+Cl) type in first and the second terrace areas, respectively. The mixing of these two types depends on the local conditions, such as pumping or permeability variations.Hunchun city is a pollution source for local water resources due to its uncontrolled sewage and urban discharge. In a previous study of the southwestern part of the Hunchun basin, groundwater contamination by Fe, Mn and NO₃-N was reported. In addition, this study identified Cd and F as prevailing contaminants in the water resources. Pollution of water resources by these contaminants appeared to be affected by the application of fertilisers, irrigation practice, variation of aquifer characteristics, solubility of mineral phases, and discharge of domestic sewage. Wide distribution and high levels of Cd and F in surface- and ground waters could pose significant problems if they are utilised as major water supply sources.     

Microwave treatment and struvite recovery potential of dairy manure

Microwave digestion of liquid dairy manure was tested for the release of nutrients, such as orthophosphates, ammonia-nitrogen, magnesium, calcium and potassium, both with and without the aid of an oxidizing agent (hydrogen peroxide). The orthophosphate to total phosphorus ratio of the manure increased from 21% to greater than 80% with 5 minutes of microwave treatment. More than 36% of total chemical oxygen demand (t-COD) of the manure was reduced when microwave digestion was assisted with peroxide addition. In addition, the volatile fatty acids (VFAs) distribution shifted to simpler chain acids (acetic acid in particular) with an increase in operating temperature. In the second part of the study, digested manure with increased soluble phosphate was tested for the recovery of struvite (magnesium ammonium phosphate) at different pH. It was found that up to 90% of orthophosphate can be removed from the solution. Overall, it was concluded that the oxidizing agent-assisted microwave digestion process can be used upstream of anaerobic digestion, following which the anaerobically digested manure can be used for struvite recovery. Thus, this microwave digestion process presents the potential for enhanced efficiencies in both manure digestion and struvite recovery.     

Photocatalytic pre-treatment with food-grade TiO2 increases the bioavailability and bioremediation potential of weathered oil from the Deepwater Horizon oil spill in the Gulf of Mexico

Using the 2010 Deepwater Horizon oil spill in the Gulf of Mexico as an impetus, we explored the potential for TiO₂-mediated photocatalytic reactive oxygen species (ROS) generation to increase the bioavailability (solubility) and biodegradability of weathered oil after a spill. Food grade TiO₂, which is FDA approved for use as food additive in the United States, was tested as a photocatalyst for this novel application. Photocatalytic pre-treatment (0.05 wt.% TiO₂, UV irradiation 18 W m^?2, 350–400 nm) for 24 h in a bench top photoreactor increased the soluble organic carbon content of weathered oil by 60%, and enhanced its subsequent biodegradation (measured as O₂ consumption in a respirometer) by 37%. Photocatalytic pre-treatment was also tested outdoors under sunlight illumination, but no significant increase in solubility or biodegradation was observed after 11 d of exposure. Although sunlight irradiation of food-grade TiO₂ generated ROS (assessed by the degradation of 4-chlorophenol as a probe compound), the efficacy of weathered oil pre-treatment was apparently hindered by sinking of the photocatalysts under quiescent conditions and illumination occlusion by the oil. Overall, results indicate that photocatalytic pre-treatment to stimulate bioremediation of weathered oil deserves further consideration, but controlling the buoyancy and surface hydrophobicity of the photocatalysts will be important for future efforts to enable ROS generation in proximity to the target compounds.     

Evaluation of the antifungal effects of bio-oil prepared with lignocellulosic biomass using fast pyrolysis technology

This study was performed to investigate the utility of bio-oil, produced via a fast pyrolysis process, as an antifungal agent against wood-rot fungi. Bio-oil solutions (25-100 wt.%) were prepared by diluting the bio-oil with EtOH. Wood block samples (yellow poplar and pitch pine) were treated with diluted bio-oil solutions and then subjected to a leaching process under hot water (70 °C) for 72 h. After the wood block samples were thoroughly dried, they were subjected to a soil block test using Tyromyces palustris and Trametes versicolor. The antifungal effect of the 75% and 100% bio-oil solutions was the highest for both wood blocks. Scanning electron microscopy analysis indicated that some chemical components in the bio-oil solution could agglomerate together to form clusters in the inner part of the wood during the drying process, which could act as a wood preservative against fungal growth. According to GC/MS analysis, the components of the agglomerate were mainly phenolic compounds derived from lignin polymers.