Phosphorus (P) removal by aluminum sulfate solution was investigated with varying pH and initial P concentrations. P removal was the highest at around pH 6. The pH range where P removal occurred was slightly wider at higher initial P concentrations. Compared to theoretical calculations, it was confirmed that AlPO4 precipitation was the main reason for P removal at low pH. At high pH, where there should be no AlPO4 precipitates, the P removal by adsorption of amorphous Al(OH)3 precipitates was experimentally observed. The P removal by adding amorphous Al(OH)3 precipitates prepared before the adsorption experiments, however, was lower than that by injecting aluminum sulfate solution because the prepared precipitates became larger, leading to less specific surface area available for adsorption. Ions other than sulfate had little influence on P removal.

간척이 식생 분포에 미칠 영향을 분석하기 위하여 새만금 간척지구 내 안서 포구 앞 조간대와 기수 지역에서 2003년부터 2004년에 걸쳐 식생과 토양특성을 분석하였다. 이 지역의 조간대와 기수 지역에 출현한 식생은 모두 염생식물로, 조간대는 3종의 염생식물이 출현하여 단순하였고, 만조대와 기수 지역은 각각 9종과 8종이 출현하여 조간대에 비하여 다양하였다. 식물종은 조간대에서 해홍나물(Suaeda maritima), 갯질경(Limonium tetragonum) 및 칠면초(Suaeda japonica)가, 기수 지역의 비침수 지역에서는 해홍나물, 갯질경 및 갯개미취(Aster tripolium)가, 기수 지역의 침수 지역에서는 갯댑싸리 (Kochia scoparia var. littorea)가 우점하였다. 토양화학성을 분석한 결과, 조간대 내에서 식물종의 출현은 토양의 전기전도도(electrical conductivity, EC), Na+ 및 Cl-의 농도가 상대적으로 낮은 지역에서 이루어졌다. 식물종 간의 EC 농도는 동일지역 내에서는 유사하였으나, 서로 다른 지역에서는 동일종 간에도 뚜렷한 차이를 보여, 식물종의 출현 유무는 토양환경의 차이에 의해 결정되었다. 조간대 및 기수 지역에서 식물종의 출현은 토성과 토양화학성에 따라 다름으로써, 식생의 분포는 토양환경의 영향을 받고 있음을 시사하였다.

An on-line digestion system based on the flow injection analysis technique was presented for the determination of total phosphorus. The system converts condensed and organic phosphoruses into orthophosphate that can be analyzed spectrophotometically. The reaction between orthophosphate and ammonium molybdate in a strong acid medium forms the yellow complex of phosphomolybdate which is next reduced to a molybdic blue complex by stannous chloride. The quantitation of orthophosphate is based on the absorbance of the molybdic blue. To determine total phosphorus, the digestion system was installed between the sample injector and the reaction coil with the added lines of digestion solution(potassium persulfate+sulfuric acid) and the H_2O carrier. The system has shown that the digestion efficiencies were greater than 95% for the typical condensed and organic phosphoruses. When tripolyphosphate standards were used, the calibration data showed that the linear dynamic range extended to a concentration of 1.5ppm with the detection limit of 25 ppb total phosphorus. The typical relative standard deviation was less than 2%. The proposed system was successfully applied to lake water, wastewater, and streamwater. The analytical variables such as digestion efficiency, analysis time, and reproducibility were evaluated and compared with the manual digestion method.

A simple on-line measurement system consisting of a conventional peristaltic pump, a HPLC-type heater, and a flow-through spectrophotometer is introduced for the determination of chemical oxygen demand(COD). The system was configured such that the reaction mixture in the highly concentrated sulfuric acid medium flowing through the PTFE reaction tubing was heated at 150℃ and the absorbance of dichromate was continuously monitored at 445 nm. The same oxidation principle as in the standard procedure was employed except the use of CoSO_4 as a new effective catalyst. To test the system, potassium hydrogen phthalate was selected as a COD standard material. With suitably optimized reaction condition, the applicable concentration range depends on the initial concentration of potassium dichromate in the oxidizing reagent. With 2.0×10-3 M and 5.0×10-4 M dichromate, the linear dynamic range was observed up to 400 ppm and 100 ppm, respectively. The standards in the linear ranges were shown to be completely oxidized, which was confirmed with sodium oxalate or Mohr`s salt. In all cases, the typical reproducibility for between-runs was 2% or less. The proposed measurement system provides the valuable information for the further development of automated analysis system based on the present standard procedure.

The reaction rate, equilibrium, and flow injection analysis methods were fundamentally evaluated for the determination of aqueous ammonia. The selected indophenol blue method was based on the formation of indophenol blue in which ammonium ion reacted with hypochlorite and phenol in alkaline solution. In the optimized reaction condition, the reaction followed 1st order reaction kinetics and the final product was stable. The absorbance measurements before and after the equilibrium were utilized for the reaction rate and equilibrium methods. The reaction rate methods, based on the relative analytical signals for the possibility of eliminating interferents, were shown to have good linear calibration curves but the detection limit and the calibration sensitivity were poorer than those in the equilibrium method. The detection limits were 32-49 ppb and 24 ppb for the reaction rate and equilibrium methods, respectively. In the flow injection analysis, the absorbance was measured before the equilibrium reached and thus resulted in 30% reduction of calibration sensitivity. However, the detection limit was 11 ppb, indicating that the peak-to-peak noise for the blank was remarkably improved. Compared to the manual methods, the optimized experimental condition in a closed reaction system reduced the blank absorbance and the inclusion of ammonia from the atmosphere was prevented. In addition, highly reproducible mixing of sample and reagents and analytical data extracted from continuous recording showed excellent reproducibility.