A~tract--The Cretaceous/Tertiary (K/T) boundary is marked by extensive changes in the sedimentary fossil record of continental and marine life. Organic matter in sediments from above and below the K/T boundary has been studied to identify consequences of the biotic extinctions and of the changes in biological productivity which occurred at this time. Data from locations encompassing a variety o...

improvement of soil properties through sustainable agriculture requires suitable management of plant residues. this study was conducted to investigate the effect of different types and managements of plant residue on soil physical properties in a field experiment as factorial based on rcbd with three replicates. the first factor was residue type including barley straw and alfalfa residue, and t...

Biogeochemical and stable carbon isotopic analysis of black-shale sequences deposited during an Albian oceanic anoxic event (approximately 112 million years ago) indicate that up to 80 weight percent of sedimentary organic carbon is derived from marine, nonthermophilic archaea. The carbon-13 content of archaeal molecular fossils indicates that these archaea were living chemoautotrophically. The...

.soil microorganisms are important agents in nutrient cycling and energy flow. they are extremely sensitive to environmental changes. soil microbial biomass has been proposed as an index of soil stress and disturbance. the objective of this study was to determine the effects of barley (hordeum vulgare l.) residue amounts, burning, nitrogen fertilizer levels and tillage management on organic car...

Although saline tidal wetlands cover less than a fraction of one percent of the earth's surface (~0.01%), they efficiently sequester organic carbon due to high rates of primary production coupled with surfaces that aggrade in response to sea level rise. Here, we report on multi-decadal changes (1972-2008) in the extent of tidal marshes and mangroves, and characterize soil carbon density and sou...

abstract this study was conducted under cold climate condition in khorasan during 2006-2008 growing seasons to evaluation of soil fertility in wheat-based double cropping systems under different rate of nitrogen and return of crop residues. a randomized complete block design with split-split plot arrangement and three replicates was used. main plots were five crop rotations namely: wheat-wheat,...

abstract introduction: due to environmental and human health concerns related to humic acid (ha), mainly leading to disinfection by-products creation, removal or reduction of this matters is a necessary for drinking water suppliers. based on resistive economy map road and move to self-sufficiency, it is necessary to produce our need in water treatment industry. one of the main consumed material...

The bacteria and their phages are the most abundant constituents of the aquatic environment, and so represent an ideal model for studying carbon regulation in an aquatic system. The microbe-mediated interconversion of bioavailable organic carbon (OC) into dissolved organic carbon (DOC) by the microbial carbon pump (MCP) has been suggested to have the potential to revolutionize our view of carbo...

understanding the relationship between soil and plant is essential for reclamation of degraded lands. in order to investigate the relationship between atriplex halimus density with carbon sequestration the rangeland of incheborun was studied. soil samples were collected randomly by auger in the depth of 0-30 cm of the soil profile in three different plant densities (400 stand per hectare) with ...