soil characteristics is very important in water erosion processes. the present investigation was conducted in gully lands of ardebil province, iran, to assess the role of soil texture and structure on aggregate stability using wet sieve method. to achieve the study purposes, mean weighted diameter of aggregates was calculated, and its relationships with lime and clay percentages, sodium absorpt...

Ž . Not only the amount of organic carbon in soil is important for soil organic matter SOM stability, but also its physical and chemical properties. The appropriate technique for the assessment of SOM dynamics can vary between soil types, and information about this is lacking for Ferralsols of the central Amazon basin. First, this work identified SOM pools which are sensitive to land-use change...

To explore the principle of chiral induction in inorganic clusters, chiral organic cations with two stereocenters, R- and S-BPEA, are used to encapsulate a series of polyoxometalates (POMs) bearing different structures and transition absorption bands in aqueous solution, constructing a series of chiral supramolecular complexes. Due to the induction of chiral organic cations, POMs possessing bot...

The hydrothermal synthesis of two new inorganic-organic hybrid materials in which PDA (PDA = 1,10-phenanthroline-2,9-dicarboxylate) is connected to a well-defined Keggin-type polyoxometalate anion (POM) and a Ln(III) cation (POM = [SiW12O40]4−; Ln = Eu3+ (1), Er3+ (2)), are reported. These hybrids are characterized by elemental analyses, IR spectra and single-crystal X-ray diffraction. Single-c...

Nitrogen (N) and phosphorus (P) availability, in addition to other macroand micronutrients, determine the strength of the ocean’s carbon (C) uptake, and variation in the N : P ratio of inorganic nutrient pools is key to phytoplankton growth. A similarity between C : N : P ratios in the plankton biomass and deep-water nutrients was observed by Alfred C. Redfield around 80 years ago and suggested...

In the presence of oxygen, organic compounds can be oxidized by zerovalent iron or dissolved Fe(II). However, this process is not a very effective means of degrading contaminants because the yields of oxidants are usually low (i.e., typically less than 5% of the iron added is converted into oxidants capable of transforming organic compounds). The addition of polyoxometalate (POM) greatly increa...

We report sorption isotherms and uptake kinetics for phenanthrene and pyrene with three organic model sorbents: polyoxymethylene (POM), coke, and activated carbon. We combine batch equilibration and kinetic experiments with the direct observation of the long-term diffusion of phenanthrene and pyrene as measured within cross-sectioned particles using microprobe laser-desorption laser-ionization ...

Particulate organic matter (POM) is an important source of energy in aquatic systems, where decomposition rates have traditionally been studied using the litter-bag technique. However, this method has limitations for estimating in situ decomposition rates, especially for fine particles. In this study the litter-bag technique is combined with measurements of microbial enzyme activities to estima...

The impact of human activities on the concentrations and composition of dissolved organic matter (DOM) and particulate organic matter (POM) was investigated in the Walloon Region of the Meuse River basin (Belgium). Water samples were collected at different hydrological periods along a gradient of human disturbance (50 sampling sites ranging from 8.0 to 20,407 km) and during a 1.5 year monitorin...

Alley cropping may promote greater sequestration of soil organic carbon. The objective of this study was to examine spatial variability of soil organic carbon (C) and nitrogen (N) fractions relative to tree rows in established alley cropping systems in north central Missouri. Soils were collected to a depth of 30 cm from two alley cropped sites, a 19-yr-old pecan (Carya illinoinensis)/bluegrass...