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Urbanization transforms natural river channels, and surface water of some rivers disappeared over time. How and whether the subsurface domains of the original waterways and aquifers connecting them (a phantom of historical landscape) are functional is not known. This study examined the effects of tributary groundwater inflow on the response of river–riparian organisms in an alluvial mainstem river in northern Japan, where the tributary disappeared over the course of urban landscape transformation.A 2.8‐km lowland segment of the mainstem gravel‐bed river was examined for water properties and the river–riparian food web. In addition, watershed‐wide water sampling was conducted to isotopically distinguish several types of groundwater that contributed to the hyporheic water in the study segment. Altitude had a clear effect on the hydrogen/oxygen stable isotope ratios in the river water collected across the watershed.Groundwater unique both in chemical and isotopic signatures occurred in several spots within the study segment, and its properties resembled and its upwelling locations matched groundwater from a tributary river whose surface channel disappeared 60 years ago. Positive numerical increases in abundance and/or a sign of nitrogen transfer in river–riparian communities (algae, invertebrates and riparian trees) originating from groundwater high in nitrate with elevated nitrogen stable isotope ratios were found.We demonstrated that tributary groundwater with unique chemical properties manifested by an urban watershed river network continued to have trophic effects on biota across the river–riparian boundary in the mainstem river, even after urbanization transformed the tributary into a phantom river. We highlighted the legacy effects of landscape transformation in the subsurface domain and the significance of scrutinizing the past landscape and hydrological connectivity at the watershed scale in urban environments. [ABSTRACT FROM AUTHOR]

When a single crystal of yttrium iron garnet, YIG (Ga:0.0625) with native defect of oxygen is exposed to optical light at 77 K, disaccommodation of magnetic permeability (DA) is observed to occur around 140 K and 210 K, as reported earlier. Furthermore, the third DA peak independent of illumination is found around room temperature in some samples, when the sample temperature is raised up to 400 K. The mechanism of these DA peaks and photoinduced irreversible decrease of initial permeability (PME) is discussed, qualitatively, in a systematic way.

An experimental study of the complicated u(sub i)-T curve produced by whitelight study or HeNe-laser-light illumination of thick films of YIG at 77 K is presented. It is suggested that there is photoinduced structural distortion around oxygen vacancies due to a photoinduced change of charge imbalance.

Presents a study that observed the complex permeabilities during and after illumination of an yttrium iron garnet single crystal. Activation energies of the triple peaks; Dependence of the height of each peak on the illuminating time of exciting light; Magnitude of distortion of iron.

Focuses on the thermal behavior of the photoinduced change of the imaginary part of the permeability. Preparation of single crystals of yttrium-iron-garnet; Variation of permeability with temperature and frequency after illumination.