Co-inoculation of Capitella sp. I with its synergistic bacteria enhances degradation of organic matter in organically enriched sediment below fish farms

A polychaete, Capitella sp. I has been shown to degrade organics actively in organically enriched sediment below fish farms. Our aim of the present study is to enhance the biological treatment of sediment by co-inoculation of Capitella sp. I with bacterial isolates that possess high degrading potential for organic matter. We isolated a total of 200 bacterial strains from fecal pellets, burrow lining, worm body, and sediment, and selected six of them for the degradation experiments in the sediment microcosms. With two out of the six isolates, tentatively identified as Vibrio sp. and Vibrio cyclitrophicus by 16SrDNA sequence, we found the TOC reduction rate was stimulated in sediment co-inoculated with the worms and each of the bacteria. In contrast, this was not observed in sediments inoculated only with the worms or the bacterium. These results strongly suggest that co-inoculation of Capitella sp. I with bacteria improves biodegradation.     

Effect of air mobility in a soil pipe on water flow through a model hillslope after pipe clogging

Soil pipes (continuous macropores expanding laterally in the soil subsurface) are a key factor controlling hillslope water cycles and sediment transport. Soil pipes usually enhance slope stability under rainfall events through their high water drainage ability, and pipe clogging by sediments is regarded as a risk for slope failure. In this study, we conducted a bench-scale pipe clogging experiment to clarify the effect of air mobility in soil pipes on water flow and water pressure build-up in the slope at the clogged point. Before pipe clogging, the soil pipe drained rainwater effectively and lowered the groundwater table. After the pipe clogging event, the mobility of air in the soil pipe before the clogging determined the water flow in the slope. When the air in the soil pipe connected to the atmosphere and moved freely, the water level in the soil pipe increased at the pipe clogging, and water pressure build-up was limited near the pipe outlet. On the other hand, when air in the soil pipe was entrapped by the clogging, water pressure suddenly increased, and the groundwater table of the whole slope rose correspondingly. This study clearly demonstrated the importance of pipe morphology with respect to air connectivity between the pipe and atmosphere to elucidate the water flow and slope stability during the pipe clogging event. © 2019 John Wiley & Sons, Ltd.     

Spatial variability and correlation of environmental proxies during the past 18,000 years among multiple cores from Lake Pumoyum Co,Tibet, China

Multiple cores from Lake Pumoyum Co, southern Tibet, provide an improved understanding of the spatial distribution of lake sediments, and how well they represent the paleo-climate. Comparative study of these cores using AMS ¹⁴C dating and environmental proxies clarified their relationships with environmental changes. Our work focused on understanding the spatial similarities among cores covering different time scales, and evaluating variations in sedimentary processes across sites. The four studied cores demonstrate different sedimentation rates, but environmental proxies help synchronize the timing of environmental variations. Sediment variables such as total organic carbon (TOC), inorganic carbon (IC), and grain size in different cores correlate well and corroborate changing trends over the past 10,000 cal years. Differences in sedimentation rates and facies among core sites probably result largely from differences in water depth. The core from the deepest site displays the highest average sedimentation rates and the highest accumulation rates of TOC, but lowest content of IC. Two cores from somewhat shallower sites have plant residues in their lower sections and record similar variations in both the number of layers and their depositional ages. Our results do not indicate any significant variation in sedimentation pattern or its related factors among the three sites. A single core from the deepest site could adequately represent the total lake environment over the time span covered. But cores from somewhat shallower sites might reveal important shifts in the environment over a longer time period.     

The absence of apparent correlations between iras and optical spectral features of late-type stars

The spectral signatures of circumstellar dust shells (CS) of late-type stars cannot be tied in a simple manner to their optical spectral features. The spectral indices of featureless low-resolution spectrometer (LRS) spectra of K and early-M (M0-M5) stars are consistent with that of the Rayleigh-Jeans law and those of late-M (M6 and later) stars tend to have lower values showing CS radiation. There is no correlation observed between the optical sub-type and the 10 m emission strength for M stars. The absence of a simple relationship is also evident for C stars where the temperature and abundance indices show no correlation with the 11 m emission strength. The sample is confined to the IRC stars identified with accurate spectra observed by the LRS of IRAS. The IRC stars are the whole sky survey done with the 2 m band, where late-type stars are bright and interstellar extinction is one-tenth of the visual colour band.