Although landfills are the primary method of waste disposal, a leakage of water from the landfill site could cause an environmental pollution. A carbonization technique was recently developed to reduce volumes of sewage sludge; however, carbonized sludge is of limited use. In this study, the usage of carbonized sewage sludge is proposed to prevent pollutants from leaking out of landfills. To confirm this hypothesis, zinc solutions under various pH were used as modified heavy metal-containing leachate. It was found that the carbonized sewage sludge not only neutralized the acidic leachate solution, but also phosphates released from the sludge reacted with heavy metals to form insoluble materials. These experimental results were also assessed on the basis of chemical equilibrium. It was suggested that the usage of carbonized pellets as in landfill site was possible to minimize the environmental pollution by heavy metals leached from landfill.
Airborne particulates were collected at Wajima in Noto peninsula, Ishikawa, Japan, every week from September 17, 2004 to June 3, 2005. Both PAHs and NPAHs in the extracts from the particulates were analysed by HPLC with fluorescence and chemiluminescence detection. During the period of central heating of China (October 15 — April 15) and the period of sandstorms detected in Wajima (April 15 — 21), atmospheric concentrations of PAHs and NPAHs increased significantly when the northwest wind was predominant at Wajima. The concentration ratio of NPAHs to PAHs was not similar to that of Japanese urban air but similar to that of Chinese urban air. The increase of the atmospheric concentrations of PAHs and NPAHs could attribute to a long-range transportation of combustion particles from China.
Radiochemical analysis using iron tracer, 55Fe, with liquid scintillation counting is a simple, sensitive and reliable method for determination of low-level iron, and is useful for iron speciation in laboratory culture experiments of marine phytoplankton. In this paper, we studied interferences from the components of the culture media, established the analytical conditions, and measured iron distribution including dissolved, particle, intra- and extracellular iron in marine phytoplankton cultures. The results from iron uptake experiments showed that bioavailability of iron to phytoplankton was related to the iron speciation in the presence of the chelating ligands.
Some plants that accumulate the arsenic compounds have attracted attention as hyperaccumulators, and contribute to metal-extraction technique for the clean-up of contaminated environments. This study investigated the effects of arsenic species and bacterial activities on the arsenic uptakes of the hyperaccumulator fern Pteris vittata. The microbial activities in the lake water mineralized DMAA to inorganic arsenic, and some bacterial isolates degraded DMAA. When P. vittata was cultivated in the hydroponic culture medium, the plant accumulated inorganic arsenic to about 1700 As-mg/kg, while it hardly accumulated dimethylarsinic acid (DMAA) showing lower accumulation of below 50 As-mg/kg. The DMAA-mineralizing bacteria and the lake water sample, which were added into P. vittata culture medium, increased until 20 fold the plant arsenic accumulations. Furthermore, the bacterial addition also induced the arsenic accumulation of P. vittata, which were cultivated in the sterilized normal soils spiked with DMAA or the arsenic contaminated soils. Presumably, the bacterial mineralization supported the plant accumulate DMAA via inorganic arsenic.
To enhance the degradation of phenol in an electrolyte-containing model wastewater using a combined photocatalyst of TiO2 and Fe(ClO4)3, the optimum operation conditions for a continuous flow-type shallow photoreactor combined with TiO2 coagulation were examined. The combination of Fe(ClO4)3 addition to a TiO2-suspension in tap water (pH = 3) and a flow rate of 400 mL min-1 (irradiation time: 50 min) enhanced the degradation of phenol more than that in distilled water while depressing the coagulation of TiO2 by the electrolytes in tap water. The result was explained by the enhanced formation of ·OH radicals in the Fe(III)/Fe(II) catalytic cycle and the repulsion between the positively charged TiO2 particles. After the degradation of phenol, neutralization of the suspension enabled sedimentation of the TiO2 particles.
The effects of oxygen supply on microbial xylitol production from corn cobs using Candida magnoliae were investigated. The xylitol production by C. magnoliae was strongly influenced by oxygen supply during fermentation and the successful xylitol production occurred only when the oxygen transfer rate (OTR) into a fermentor ranged from 1.6 mmol-O2/L/h to 4.7 mmol-O2/L/h. The maximum xylitol yield of 0.6 was obtained at an OTR of 1.6 mmol-O2/L/h.
Liaoning Province is the political and economic center of northeast China, and is the main region of heavy chemical industries in China. So the consumption of fossil fuels is remarkably increasing and combustion particulates containing polycyclic aromatic hydrocarbons (PAHs) and nitropolycyclic aromatic hydrocarbons (NPAHs) are emitted into the atmosphere with the exhaust gas. In recent years, in addition to domestic heating exhaust, industrial and automobile exhausts have caused much air pollution in Liaoning Province. In this study, airborne particulates were collected in nine different particulate size fractions by using Andersen low-volume air samplers in Shenyang, Fushun and Tieling, Liaoning Province, during July 2001 - December 2003. Nine PAHs and ten NPAHs in the extracts from the particulates were analyzed by HPLC with fluorescence detection and chemiluminescence detection, respectively. The mean concentrations of the sums of the nine PAHs and ten NPAHs were highest in Fushun, which is an industrial city, and lowest in Shenyang, which is a commercial city, although the consumption of petroleum and coal were largest in Shenyang. The nine particulate fractions were mixed into three groups: › 7 μm, 2.1 ∼ 7 μm and ‹ 2.1 μm. In each city, more than 55% of the total PAHs and total NPAHs were found in the fine particulate fraction (‹ 2.1μm). All PAHs and NPAHs were clearly higher in winter than in summer. Our study also showed that the major contributors of atmospheric PAHs and NPAHs were coal combustion systems both in summer and winter in Fushun and Tieling. In Shenyang, atmospheric PAHs and NPAHs also seemed to be affected by coal combustion systems in winter, while gasoline-engine vehicles seemed to be a major contributor in summer.
We surveyed agricultural practices together with nitrogen concentrations in groundwater in Yanbian, Jilin, China. The nitrogenous fertilizer input into the 20 fields investigated was 100- 2190 kg-N/ha/year, (490-2190 kg-N/ha/year for vegetable fields). The nitrogen concentration was found to vary widely in groundwater beneath fields. In respect of nitrate, 65 % of sites exceeded the drinking water standard of 10 mg-N/L. Total nitrogen concentration in river water ranged from 0.7 to 12.6 mg/L; while a higher concentration was seen near Yanji city, as the river went downstream into Tumenjiang the concentration decreased. Using the statistical data, the total nitrogen loads to the water environment of the Yanbian area were estimated to be about 6.4×104 ton-N/year (0.29 ton-N/ha/year). Assuming that this amount of nitrogen goes into water in the environment without any depletion such as by denitrification, the average concentration of nitrogen in the surface water in this area was estimated to be about 12.4 mg/L. Although not so severe nitrogen water pollution is seen in this area, the nitrogen concentration in environmental water may increase in the future. Thus, careful monitoring and nitrogen load management are desirable.