Since glyphosate is used as an herbicide all over the world and mass-produced in Japan, it has become one of the complementary items set in determining drinking water quality standards in Japan. This compound has thus far been determined using derivatization-HPLC methods, which require rather complicated analytical procedures. In the present study, to determine organic phosphorus compounds including glyphosate and its main metabolite aminomethyl phosphoric acid (AMPA), glufosinate and its main metabolite 3- (metylphosphinico) propionic acid (MPPA), and fosetyl, we have developed a simple and rapid method employing liquid chromatography-inductively coupled plasma mass spectrometry (LC/ICP/MS). These compounds were directly injected to and separated in an ion exchange column using formic acid as the solvent, and phosphorus (³¹P) in the fractions was measured as ³¹P¹⁶O⁺ generated by a reaction with oxygen, which enabled high-sensitivity measurements. The calibration curves for the compounds were linear within the range of 0.02-30 mg·L^-1 (r>0.999). The recovery rates of the compounds from the river water and groundwater samples were higher than 91.6%, with relative standard deviations less than 3.8%, suggesting that the method described in this study is useful for a rapid and simultaneous determination of organic phosphorus pesticides.

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Changes in the forms of sulfur and oxygen consumed during the oxidation of hydrogen sulfide ions using activated carbon have yet to be elucidated fully. Therefore, in this study, an experiment on the oxidation of hydrogen sulfide ions in aqueous solution was carried out to investigate altered forms of the sulfur and oxygen consumed. The oxidation of hydrogen sulfide ions was promoted by activated carbon, and the oxidation of sulfur resulted in the formation of sulfate and thiosulfate ions. Additionally, X-ray photoelectron spectrometry indicated that elementary substances of sulfur adsorbed onto activated carbon. A material balance with an 84% abundance ratio of sulfur oxides and 82% oxygen consumption based on stoichiometry was calculated. The oxidized sulfur compound was confirmed to be safer than hydrogen sulfide ions.

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The biochemical oxygen demand（BOD）and water temperature data of treated water of Johkasou were obtained by the legal inspection of Johkasou located at 160,000 sites in total. These inspections were carried out in each inspection month, and data were collected, tallied, and then analyzed. The results revealed that the water temperature observed at the time of inspection did not affect the average BOD. Instead, a highly linear correlation was observed, indicating that the average water temperature in 4-5 months until the inspection (which lies in the range 11-25 °C) affects the BOD of treatment water. This signifies that the condition of Johkasou observed at a specific time is affected by the cumulative effects of water temperature from a certain time in the past to the time of observation. Furthermore, although earlier inspections of Johkasou have shown that the BOD of treatment water was lower when the water temperature observed at the time of inspection was low, evaluating the moving-average water temperature with respect to the treatment performance of Johkasou reconfirmed that the BOD of treatment water was lower, while the average water temperature was higher, as anticipated in the past.

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Although the importance of potable groundwater has been declining in recent years in Okinawa, the groundwater is still indispensable for supporting daily lives. A continuous monitoring of groundwater is carried out in accordance with the provisions of the Water Pollution Control Law. This monitoring consists of an overview and a continuous monitoring survey. On the basis of the results of the Okinawa Prefectural Government survey in FY2010, the amount of arsenic exceeded the environmental standard at four out of seven sampling sites. The total mercury level was below the detection limit at three sampling sites. The amounts of volatile organic compounds (VOCs) were either not detected or below the environmental standards at four sampling sites. The nitrate- and nitrite-nitrogen level was below the environmental standard at one site. The contamination by VOCs and nitrate- and nitrite-nitrogen is due to human activities. However, in Okinawa, on the basis of the results of the field survey, arsenic and total mercury are considered to be of natural origin. Arsenic in groundwater can be derived via two pathways: (1) in its reduced condition, arsenic adsorbed to iron is eluted to groundwater when iron in soil is eluted to groundwater and (2) arsenic adsorbed to iron in minerals is eluted when minerals come to contact with slightly alkaline groundwater. The source of total mercury contamination is assumed to be mercury vapor which rises from deep underground along faults. The findings of the survey from FY1989 to FY2010 will serve as important reference data when considering the quality of groundwater in Okinawa in the future.

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