Molecular identification of fecal pollution sources in water supplies by host-specific fecal DNA markers and Terminal Restriction Fragment Length Polymorphism profiles of 16S rRNA gene.

Specific fecal DNA markers were investigated for major pollution sources, cow, human, and pig, and occurrence of the identified markers was analyzed in river waters using Terminal Restriction Fragment Length Polymorphism (T-RFLP) techniques and sequencing of 16S rDNA of Bacteroides-Prevotella. The unique and specific DNA markers for cow and human were identified as a 222 bp and 60 bp peak in HaeIII T-RFLP profiles, respectively, and the pig-specific marker was not identified but the unique T-RFLP profile of pig could be used as a substitution. Human-specific marker was detected in most of the river waters tested (92.1%) and T-RFLP profiles of river waters were shown to be similar to those of human feces. Cluster analysis of T-RFLP data showed that the fecal sources were multiple (human plus cow and human plus dairy cow) in most of the river waters. The phylogenetic analysis for the clones recovered from the fecal and water samples showed that the clones from cow formed a discreet cluster from those of other sources. The other clones from human, pig, and river water formed two groups all together. The results of this study could be used to identify and control the fecal pollution source in the bodies of water in Korea.

Phosphorus release rates from sediments and pollutant characteristics in Han River, Seoul, Korea.

The Han River is 469.7-km long and drains a 26219-km(2) watershed. The sediments in the river are highly polluted due to inputs from upstream tributaries as well as partially treated municipal wastewaters that are discharged to the river. The water quality and strategy for control are important because the river is the primary drinking water supply for the City of Seoul, as well as being a major source for irrigation and industrial water. The Jamsil submerged dam partitions the river to isolate an upstream area for drinking water, but also captures sediments. Samples from four sites were studied to determine sediment pollutant concentrations and phosphorus release rates. Phosphorus tends to desorb from sediments when the concentration of overlying water is less than 1.4 mg/l. Water column P concentrations range from 0.04 to 0.1 mg/l, which suggests that sediments will act as a P source. In a series of batch experiments, P was released at approximately 15-20 mg/m(2)week in the winter (1-5 degrees C) and as much as 90 mg/m(2)week in the summer (20-24 degrees C), and is also a function of pH and dissolved oxygen concentration. The sediment total phosphorus concentration, which averages 833 mg/kg, is evenly distributed among non-apatite-P (33%), apatite-P (32%) and residual-P (34%). An equilibrium model is proposed to describe release rate.

Removal of reactive dye using UV/TiO2 in circular type reactor.

Photocatalytic degradation of reactive dye, Red 120, was carried out on TiO2 particles as photocatalyst under UV irradiation. In this experiment, comparison on the removal of reactive dye by photolysis using UV light alone, photocatalyst adsorption using TiO2 alone and photocatalysis using UV light with photocatalysts as well as the effect of experimental parameters such as the number of column employed, intensity of the light, pH and TiO2 dosage affecting the reaction efficiency of photocatalytic degradation of reactive dye in circular type reactor was examined. The results of this indicate that with both UV light illumination and TiO2 present, reactive dye was more effectively eliminated than with either UV or TiO2 alone. Photocatalytic degradation of reactive dye increased linearly with increasing UV light intensity. However, over 18 mW cm(-2) of UV light intensity, the efficiency reached a plateau. The photocatalytic degradation rate was greater in acid media than in alkaline media. Photocatalytic removal efficiency of reactive dye increased with increasing TiO2 dosage. However, over 1.5 g L(-1) of TiO2 dosage, the efficiency reached a plateau.