Perfluoroalkyl acid (PFAA) is diffused into the environment and detected in wildlife and its environmental persistence and accumulation is becoming a major concern. In this study, we determined the homolog distribution of 15 PFAA in samples of medaka (Olyzias latipes) , surrounding water, and sediment collected from 5 sites in Japan. PFAA concentrations in environmental water, sediment, and medaka differed depending on the sampling site; however, each PFAA composition ratio was almost constant within these sampling sites. The PFAA bioconcentration factor (BCF) in medaka was related with the octanol/water partition coefficient (Log K_ow) of PFAA. PFAA concentrations in the water samples had better correlations with those in the sediment samples not per unit dry weight, but per unit ignition loss (IL) . In addition, between sediment and medaka, good correlations were found when the comparison was done with the PFAA concentrations of sediment per unit IL. The PFAA accumulation in medaka was estimated by multiregression analysis using the PFAA concentrations in sediment per unit IL, gender, and body length. The PFAA concentrations in sediment per unit IL were significantly related to accumulation in medaka.

Soil contamination and accompanying groundwater contamination by heavy metals is a serious environmental problem worldwide. In this study, sorption properties of lead and cadmium onto kaolinite under the presence and absence of hydroxamate siderophore (desferrioxamine B, DFOB) were investigated. The obtained insights were then used to interpret the results obtained from the experiments performed to investigate the influence of DFOB on the immobilization performance of lead and cadmium in kaolinite using magnesium oxide (MgO) . The experimental results and species calculation showed that DFOB influenced the sorption properties of these heavy metals, but the way and magnitude of the influence depended on the aqueous pH. The addition of DFOB enhanced the sorption of these heavy metals at pH below 6.5, while the opposite trend was observed at pH above 6.5 owing to the formation of complexes between DFOB and heavy metals. These results indicated that DFOB negatively influences the immobilization performance of heavy metals by MgO because the addition of MgO increases the soil pH to around 10. In fact, the results of leaching tests performed with leaching solutions of pH5.8-6.3 at a solid-liquid ratio of 1:10 (w/v) revealed that DFOB increased the leaching levels of both lead and cadmium.

Monthly water temperature data from routine observations by research vessels, which are not conducted on the same day every year, includes not only interannual but also seasonal variations. In this study, using the monthly observation data for Osaka Bay from 1981 to 2010, we calculated continuous normal water temperature by interpolating between observations and normalized the anomalies. Normal temperature was expressed as a finite Fourier series, which had extreme values in mid-to-late February and August, and its phase difference from normal values of solar radiation and air temperature in Osaka was estimated at about 57 and 20 days. Time series of the anomalies exhibited no significant linear trend, but showed a significant upward shift in November 1993. Fisheries statistics suggested this temperature shift could affect fishery catches of some cold-water and warm water fishes.

To clarify the effects of the musty odor algae Coelosphaerium sp. on the physiological activity and uptake of musty odor adhesion components by Corbicula japonica, changes in its filtration rate and condition index and the content of geosmin and Chl.a within its soft tissue by sand exclusion in Lake Shinji in 2009 were surveyed. The abundance of Coelosphaerium sp. increased from April to May and from September to December, coinciding with the musty odor periods. The filtration rate of C. japonica decreased in spring when Coelosphaerium sp. dominated. Reduction in the condition index was observed in autumn. We suggested that dominant algae, including Coelosphaerium sp., were consumed by the clams during the musty odor period, leading to their reduced physiological activity. The musty odor of C. japonica was controlled by sand exclusion during the early stage of the musty odor period, and geosmin was not detected in the soft tissue of C. japonica. It is likely that the musty odor of C. japonica is caused by the direct uptake of Coelosphaerium sp. in the body. In contrast, the musty odor was controlled in the later period by sand exclusion and the decrease in the geosmin concentration in the soft tissue was limited. It is likely that geosmin moved into the tissues during the later period.

Microbial source tracking of fecal pollution on Kabushima Beach was investigated using four host-specific genetic markers from May 2014 to December 2016. The numbers of Escherichia coli, total, and fecal coliforms were measured in order to monitor the fecal pollution. During the swimming season, the number of fecal coliforms was lower than 4.0 × 10² CFU 100 mL^-1. In May 2014 and 2015, however, fecal coliform concentrations were very close to1.0 × 10³ CFU 100 mL^-1, which is the upper limit of the Japanese standard value for a swimming beach. The human-, cow-, pig-, and seagull-specific markers were used to identify the sources of fecal pollution. These markers showed 90 to 100% sensitivity and over 80% specificity when tested with sewage and different animal feces. The concentrations of the human-specific marker on the beach were the highest in May, and those of the marker for the black-tailed seagull were high from May to July. In contrast, the cow- and pig-specific markers were not detected. These results suggested fecal contamination on the beach derived from human waste and the feces of black-tailed seagull.

Microplastics pollution has recently drawn worldwide attention, and may have negative effects on ecosystems. Microplastics are plastic smaller than 5 mm. This study documents microplastics larger than 100 μm in seven fish species from five Japanese bays and Lake Biwa. 197 fish individuals were examined. A total of 140 microplastics particles were found in the digestive tracts of 37.6% of all fish. All species except Sardinella zunasi had ingested microplastics in all areas. The mean number of microplastics particles was 1.89±1.41 per individual fish. Most microplastics were polypropylene (40.7%) and polyethylene (35.0%) as identified by Fourier Transform Infrared Spectrometer (FT-IR) . The median of the mean sizes of microplastics was 543 μm as measured using a microscope and digital camera. The fish species were divided into filter feeders and the others on the basis of modes of ingestion. 54.6% of 97 individuals of filter feeders had ingested microplastics, and the total number of particles was 112. The mean number of microplastics particles in filter feeders was 2.11±1.54 per individual fish. 21.0% of 100 individuals of the others group had ingested microplastics, and the total number of particles was 28. The mean number of microplastics particles in the others group was 1.33±0.80 per individual fish. These results indicated that modes of ingestion influence the fish’s ingestion of microplastics.