the distribution of extracellular enzyme activities in particle-size fractions of sediments was investigated in a subtropical mangrove ecosystem. five enzymes involved in carbon (c), nitrogen (n), and phosphorus (p) cycling were analyzed in the sand, silt, and clay of sediments. among these fractions, the highest activities of phenol oxidase (pho), β-d glucosidase (glu), and n-acetyl-glucosimin...

Ponds receiving latrine effluents may serve as sources of fecal contamination to shallow aquifers tapped by millions of tube-wells in Bangladesh. To test this hypothesis, transects of monitoring wells radiating away from four ponds were installed in a shallow sandy aquifer underlying a densely populated village and monitored for 14 months. Two of the ponds extended to medium sand. Another pond ...

Submitted: Jul 12, 2013; Accepted: Aug 26, 2013; Published: Aug 29, 2013 Abstract: Sand production in water, oil and gas wells is usually controlled by gravel packing techniques worldwide. Consideration in the gravel pack design requires that the particle size is five or six times the formation sand depending on the formation sand median diameter. Sieve analysis result shows that the grain size...

Abstract Karkheh river’s Delta is located in the west of Khuzestan Plain and can be divided into two smaller deltas; northern delta named as (including Bostan, Sableh Neisan Deltas) southern -e- Noor Delta. Based on Galloway7 classification, river-dominated type (type 1). Considering activity, this to parts; an active part north inactive south. Orton Reading 16 placed fine-grained (muddy) categ...

Computation of accurate sediment loads in rivers where the transport of suspended sediment is at least partially regulated by changes in the upstream sediment supply requires high-resolution measurements of suspended-sediment concentration that are collected independently of waterdischarge data. To meet this objective, a multi-frequency acoustic system has been developed and tested on the Color...

sediments of the nezam-abad area, south-east of bam have been studied for the first time. sedimentary facies are composed of thin-bedded clay, silt and fine grained sand interbedded with thin laminated limestone. chemical analysis of x-ray florescent indicates that more than 50% of sediments consist of silisium and aluminum oxide that can be used for reconstruction of environment. ninety eight ...

The coastal area of the Ma river delta is formed by interaction continental and marine processes, between neo-tectonic activities exogenous natural factors human during Late Holocene. Using remote sensing geoscience research methods (granulometry, paleontology, geochemistry, clay mineralogy) geomorphological studies (geneses, morphology, dynamics) combined with field survey, this area, except d...

The particle-size distribution is one of the most important characteristics soils, which determines their properties and features main regimes. Artificial forest plantations in steppe act as a powerful environment-transforming factor, over time capable changing even quite conservative including distribution. study influence on was carried out using soil samples taken from calcic chernozem, cher...

Seismic stratigraphy and core litho-stratigraphy in the Salerno Bay inner shelf (Southern Tyrrhenian Sea) reveal significant storm deposition episodes over the last 1 ky. Three major events are preserved as decimetre thick silt/sand layers bounded at their base by erosional surfaces and sealed in the muddy marine sequences between 25 and 60 m of depth. Geochronology and chrono-stratigraphy on c...

In this study, geochemical and particle size analyses of thirty-four street sediment samples collected from an urban environment around Guanabara Bay, shows highway run-off to be a potential source of heavy metals for the pollution of near-shore sedimentary deposits. Concentrations of Fe, Mn, Zn, Cu, Pb, Cr and Ni were found to be higher in these sediments when compared to concentrations found ...