We have developed a liquid chromatography-tandem mass spectrometry (LC/MS/MS) analytical method for the simultaneous determination of 3 agricultural chemicals (iminoctadine, diquat, and paraquat) considered “complementary items” in drinking water under the Japanese Waterworks Act. Further, we evaluated the validity of the analytical method based on the results of recovery tests of each chemical from dechlorinated tap water. In the LC/MS/MS measurement of a standard solution of a mixture of agricultural chemicals, the linearity of a calibration curve and the reproducibility of repeat measurements were satisfactory. Moreover, the quantification limits were lower than 1/100 of the desired values of each chemical. Recovery tests using dechlorinated tap water suggested satisfactory recovery rates (74 to 91%) and reproducibility (3 to 7%) for each of the tested chemicals. The results satisfied the criteria of the Japanese guideline regarding water quality analysis established by the Ministry of Health, Labour and Welfare. Therefore, we propose that the simultaneous analytical method we have developed in the present study is applicable to the analysis of the 3 agricultural chemicals in drinking water.

View full abstract

Various Smart City projects have been carried out all over the world. However, the cases achieving both the environmental and economic improvements are quite rare and most of the projects cannot continue without the subsidies from their governments. Besides, most of the projects focus on a single zoning area, and Smart Grid application corresponding to the zoning characteristics has not been common. Therefore, we evaluated the environmental and economic improvements driven by the Smart Grid application to the combined zoning areas. The district consisting of residential and commercial areas was assumed. The electricity demand was estimated and the cost and CO₂ reduction were also calculated. The results showed that the CO₂ reduction by solar panels is large but the investment cost cannot be recovered in the residential district, while CO₂ reduction is smaller but the cost can be recovered in the commercial district. Hence, it was concluded that the Smart Grid application considering the combination of different zoning areas can be effective.

View full abstract

Nitrogenous disinfection by-products (N-DBPs) are currently receiving increased scientific attention due to elevated toxic effects of N-DBPs relative to disinfection by-products that do not contain nitrogen, such as trihalomethanes and haloacetic acids. In order to develop an analytical method for the determination of N-DBPs, specifically haloacetamides, in drinking water, a new method using solid phase extraction liquid chromatography mass spectrometry (SPE-LC/MS) was examined. For SPE of haloacetamides from tap water, three C18 SPE cartridges and one activated carbon SPE cartridge were tested. Although no extraction of haloacetamides from a tap water sample was observed with C18 SPE cartridges, satisfactory results were obtained with the activated carbon SPE cartridge. A validation test was conducted to determine the recovery of four haloacetamides from water samples. Accuracy (recovery) and reproducibility of the developed analytical method were assessed. Results obtained suggest excellent accuracy (recovery) and reproducibility. Further, this method was applied to assess the presence of haloacetamides in tap water samples from water treatment plants located in Japan. No haloacetamides were detected above the LOQ (limit of quantification) (0.1 - 0.2μg/L) in any water samples.

View full abstract

For analyzing the relationship with natural environment and socio-economy that characterized huge materials flow, it is important to understand the dynamics of soil and stone. However, quantitative grasp of “hidden material flow” is not sufficiency performed since it is out of material calculation process. This study presents and discusses the effectiveness of a method to estimate anthropogenic disturbance of soil and sand, based on surface elevation change over time using Digital Elevation Model (DEM). First, a case study was conducted focusing on an area where a large-scale extraction of soil and sand has occurred in Misaki-cho, Osaka Prefecture. In the case study, the viability to estimate the changes of soil movement with GIS by creating raster surface model from DEM based on counter map, aerial photo and satellite image was confirmed. As a result of the estimation sediment movement do to the volume changes as from 75.81 to 81.68 million ton between before and after soil excavation. The differences between estimates and statistics are due to the vertical accuracy of DEM, conversion rate to rock products and natural processes. Despite the estimate error induced by the vertical accuracy, satellite DEM is useful to grasp anthropogenic disturbance in data limited area.

View full abstract

We measured the heavy metal (Cd, Co, Cr, Cu, Mo, Ni, Pb, Sb, V, and Zn) concentrations and Pb isotope ratios in a sediment core collected near the center of Lake Nakaumi. The results showed that Cu, Pb, and Zn pollution started in the 1890s-1900s, whereas Co, Cr, Mo, Ni, and V pollution started in the 1950s. It is likely that their pollution was caused by effluent from metal mining and metallurgical industries around the lake. Next, the sources of Pb more recently added to the sediment since the 1900s were evaluated using a two-component end-member model based on the Pb isotope ratios. The major sources of anthropogenic Pb in the 1900s-1930s, 1940s-1980s, and 1990s-2000s may have been the mining effluent of Japanese lead ores, the exhaust particles from the smelting of imported lead ores and vehicles using leaded gasoline, and aerosols transported from the Asian continent, respectively. Moreover, the contribution of Asian outflow to the increase in Cd, Sb, and Zn concentrations in the sediment around 2000 was estimated on the basis of rainwater data. The results suggest that the contribution of Asian outflow is large for Cd and Sb but not for Zn.

View full abstract