Marine pollution caused by plastic waste is a serious global environmental issue we confront nowadays. In rice cultivation, one-shot fertilizers, which are adjusted by blending fast-acting and slow-acting fertilizer granules, are often used to save labor for fertilizer management. Slow-release fertilizer granules included in one-shot fertilizers for paddy rice are generally coated with plastic resin. In this paper, the authors investigated the amount of plastic-coated slow-release fertilizer that flowed or either remained in the 1/50 model paddy field arranged at the Yokkaichi University campus. Experimental results revealed that almost all the plastic granules coated slow-release fertilizer remained within the soil, and no granule-coated resin was contained in the drainage water.

In order to develop a treatment agent that insolubilizes fluorine in biomass ash, various phosphates compounds like calcium phosphate and aluminum phosphate or incinerated ash of sewage sludge containing a large amount of phosphorus components, were added to the biomass ash. The fluorine elution properties were investigated, and the solubility was significantly lowered by adding sulfuric acid or phosphoric acid to the agent, and showed effectiveness as a fluorine elution inhibitor.

Since the water quality of Ise Bay, especially for those of the middle and bottom layer, depends largely on the characteristics of water exchange with the outer sea, it is important to clarify the mechanism of the phenomenon and the quantities such as the exchanging rate of water mass, the amount of nutrients and oxygen transported from the outer sea. In this study, the MOVE-JPN dataset obtained by the high-resolution physical ocean model of the Meteorological Research Institute are fully utilized for the analysis. Through the study for the data from June to September of year 2011 and 2017, the intrusion of the outer sea water into the middle and bottom of Ise bay was found to occur frequently on the occasion when a cold water mass upwells along the slope of ocean floor outside of Ise Bay and causes the strong density difference between the outer sea and Ise Bay. The mechanism of the upwelling of the cold water mass is estimated as the oscillation of internal gravity wave produced at the upper part of the outer sea triggered by the variation of wind force and/or the large amount of low density brackish water supply from Ise Bay to the outer sea during a flood period. The influence of the spring and neap tide for the occurrence of the intrusion was not clearly identified because of the low spatial resolution of MOVE-JPN dataset for the flow around the mouth as well as the inside of Ise Bay. The rate of the water exchange at the bay mouth was also analyzed and compared with the author’s previous work.

Danger of microplastics for marine ecosystem is recognized and a large number of research works from various viewpoints have been conducted worldwide. However, those about the fragmentation model of plastic pieces under marine environment is limited. The fragmentation of secondary microplastics is estimated to progress primary at beaches. A lot of surveys about the number density of secondary microplastics at beaches have been performed, but the results usually lack the information about the degree of fragmentation; i.e., the progress level from virgin plastics to fully fragmented stage. In this work, by considering the physical process of fragmentation, the time dependent equation describing the number density distribution of the secondary microplastics is derived. The steady state solution for the equation has the form; f（x）=Cx^{–（β+n+1）}. Here, f: the number density distribution function, C: the integral constant,x : the size of fragment,β: the exponent of fragmentation rate, n: the dimension of fragmentation （n=1~3）. The previous beach surveys showed the value 1.6 to 4.6 for the exponent ofx that correponds to β+n+1. The causes of the difference in the exponent numbers are discussed with the author’s model. The degree of fragmentation of the four types of the secondary microplastics collected at the Yoshizaki Beach in Japan is also evaluated as an another example.

Currently, we are designing and fabricating a system using a commercially available domed screen product called Paper Dome, aiming to construct a VR experience system with a domed screen that enables an immersive VR experience without the use of VR goggles. This paper describes the design and prototyping of a projector mount for image projection and a conversion lens mount to be attached to the projector, which will be used in the system being fabricated.