Perfluorinated surfactants (PFSs) such as perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) have been detected worldwide in surface water, groundwater, seawater, drinking water and aquatic organisms. In 2009, PFOS was added to the listing of the Stockholm Convention on persistent organic pollutants, and PFOS and PFOA were also added to the items for further study of drinking water quality standard in Japan. Concerns and interests about PFSs in water environments are rapidly increasing. In this review, we organized knowledge of sources, occurrences, removal efficiencies of treatments, toxicities, bioaccumulation, management and regulations of several PFS homologues including perfluorononanoate (PFNA) and their precursors, and provided perspectives on PFS problems. In this review, we also highlighted that relatively longer-chain perfluorinated carboxylates (PFCAs) such as PFNA and perfluorodecanoate (PFDA) are more toxic and bioaccumulative than relatively shorter-chain PFCAs such as PFOA, that PFNA extensively pollutes water environments in Japan compared with the case in other countries, and that the loadings of longer-chain PFCAs have not been reduced despite the reduction of PFOS and PFOA. The pollution by PFNA is particularly of concern in Japan. Thus, management and risk control of PFS homologues including longer-chain PFSs such as PFNA are now required.

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We developed a device for measuring boron concentration in wastewater, on the basis of the high thermal neutron capture ability of boron. The device is completely different from those used the conventional measurement techniques. The main results obtained using the nuclear physics theory and experiments are as follows. (1) The device can measure boron concentration correctly in the presence of dissolved matter and suspended matter coexisting at high concentrations. (2) About the measurement precision, relative error decreases, thereby increasing boron concentration. In the boron concentration range of more than 50 mg·L^-1, the device has same precision as ICP analysis, which is the official analysis used in Japan, in terms of measurement time in minutes. (3) The device operated well at a high wastewater temperature, and a precision, the same as that of ICP analysis, was obtained by a one-month proof experiment.

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