Henry Darcy's experimental studies in 1856 of saturated water flowthrough a homogeneous porous medium contained in a vertical column have provided the basis for the quantitative description of fluid flow in a wide variety of both natural and engineered porous medium environmental systems. Extrapolation of Darcy's original observations and conclusions has led to several commonly applied equation...

First posted May 31, 2023 For additional information, contact: Director, Colorado Water Science CenterU.S. Geological SurveyBox 25048, Mail Stop 415Denver, 80225 Selenium in aquatic ecosystems of the lower Gunnison River Basin is affecting recovery populations endangered, native fish species. Dietary exposure primary pathway for bioaccumulation selenium fish, and particulate can be consumed dir...

In situ video observations and sediment core samplings were performed at two hadal sites in the Japan Trench on July, 2011, four months after the Tohoku-Oki earthquake. Video recordings documented dense nepheloid layers extending ~30-50 m above the sea bed. At the trench axis, benthic macrofauna was absent and dead organisms along with turbid downslope current were observed. The top 31 cm of se...

Mechanisms that control xylan removal during pretreatment of lignocellulosic biomass are not well understood. For example, although hemicellulose hydrolysis is virtually always assumed to follow first-order homogeneous kinetics, the increase in xylan removal with flow rate for flowthrough pretreatment systems is inconsistent with the predictions for such models, and better information is needed...

Flowthrough pretreatment with hot water only offers many promising features for advanced pretreatment of biomass, and a better understand- ing of the mechanisms responsible for flowthrough behavior could allow researchers to capitalize on key attributes while overcoming limitations. In this study, the effect of fluid velocity on the fate of total mass, hemicellulose, and lignin was evaluated fo...

Spatial variations in composition of marine microbial communities and its causes have largely been disclosed in studies comprising rather large environmental and spatial differences. In the present study, we explored if a moderate but temporally permanent climatic division within a contiguous arctic shelf seafloor was traceable in the diversity patterns of its bacterial and archaeal communities...

Concentration of total Hg, methyl Hg, and other heavy metals were determined in sediment collected along a salinity gradient in a Louisiana Gulf Coast estuary. Surface sediment was collected at established coordinates (n = 292) along a salinity gradient covering Lake Maurepas, Lake Pontchartrain, Lake Borgne and the Chandeleur Sound located in the 12,170 km(2) Pontchartrain basin estuary southe...

The regional lymph node cells of the mice sensitized with Ehrlich ascites tumor cells is known to possess a substance that shows antitumor activity on target cells (JTC-II cells). For the purpose to clarify the localization of this substance the regional lymph node cells from such sensitized mice were treated with trypsin solution of different concentrations (1.0 %, 0.2 %, and 0.01 %), and the ...

Coral reefs are globally important marine ecosystems as sites of high biotic diversity. Reef flat sediments are reasonably homogeneous in composition. This substratum is subject to gradients in water motion, grazing pressure and benthic productivity. This study used DNA fingerprinting techniques, automated rRNA intergenic spacer analysis (ARISA), and terminal restriction fragment length polymor...