Dynamics of changes in methanogenesis and associated microflora in a flooded alluvial soil following repeated application of dicyandiamide, a nitrification inhibitor.
Influence of repeated application of the nitrification inhibitor dicyandiamide (DCD), on CH(4) production and associated microflora in a flooded alluvial soil, was investigated in a laboratory incubation study. Application of DCD at the time of soil incubation resulted in a substantial reduction in CH(4) production (31% over that of untreated control). Second repeat application of DCD, on the contrary, annulled the inhibitory effect on CH(4) production, restoring it to the level of unamended soil. Application of the third dose of DCD maintained CH(4) production almost to the same extent as that of second application. The alleviation of the initial inhibitory effect of DCD on CH(4) production was linked to the enhanced degradation of DCD following its repeated application to the flooded soil. Admittedly, abatement of the initial inhibitory effect of DCD on CH(4) production in soil repeatedly amended with DCD was also related to the inhibition of CH(4)-oxidizing bacterial population and noticeable stimulation of heterotrophic bacterial population. Results suggest that repeat application of DCD with fertilizer-N to flooded rice soils might not be effective in controlling CH(4) production under field condition. (+info)
Post-Katrina fecal contamination in Violet Marsh near New Orleans.
Fecal material entrained in New Orleans flood waters was pumped into the local environment. Violet Marsh received water pumped from St. Bernard Parish and the Lower Ninth Ward. Sediment core samples were collected from canals conducting water from these areas to pump stations and from locations within Violet Marsh. Viable indicator bacteria and fecal sterols were used to assess the levels of fecal material in sediment deposited after the levee failures and deeper sediments deposited before. Most of the cores had fecal coliform levels that exceed the biosolids criterion. All of the cores had fecal sterols that exceeded the suggested environmental quality criterion. Our data show both a long history of fecal contamination in Violet Marsh and an increase in fecal loading corresponding to the failure of the levee system. The work was performed as part of the Interagency Performance Evaluation Task Force investigation into the consequences of the failures of the New Orleans levee system. (+info)
Adaptation to flooding in upland and lowland ecotypes of Cyperus rotundus, a troublesome sedge weed of rice: tuber morphology and carbohydrate metabolism.