777 research outputs found
Nutrient Cycling Index in Relation to Organic Matter and Soil Respiration of Rehabilitated Mine Sites in Kelian, East Kalimantan
Degraded soils at mine sites are often associated with decreased soil fertility. However, soil nutrient status might be improved through biomass recovery primarily from re-vegetation. This paper relates nutrient cycling index (NCI) derived from Landscape Function Analysis (LFA) to soil respiration and soil organic matter as a measure of improving soil condition after rehabilitation. Fieldwork was conducted at Kelian Equatorial Mining, East Kalimantan in June 2001. Four sites were selected representing rehabilitation work in 1994 (7 year), 2000 (1 year) and 2001 (3 month), and a reference site of undisturbed primary forest. The NCI value was calculated from scores of basal/canopy cover, litter (abundance, origin and degree of incorporation), cryptogam cover and surface roughness. Soil respiration was measured using the inverted-box method. In general, the NCI values increased with age of rehabilitation (12 to 56 %) showing a significant increase compared with the values of reference site (80%). Soil respiration varied greatly and the values were equally high (200-800 mg CO2 m-2 hr2) across all sites. Tropical soils like those of Kelian might be inherently rich of soil organism as shown by high value of soil respiration. Nevertheless, the NCI values were not systematically related to soil respiration. We found that increased organic matter may be used as early sign of functioning soil resources in degraded land
Differences in potassium forms between cutans and adjacent soil matrix in a Grey Clay Soil
International audienceCutans are common fabric features in soil and represent foci of chemical and biological reactions. The influence of cutans on potassium forms and their transformations were investigated for a Western Australian grey clay soil. Cutans and matrix soil had similar clay mineral associations with kaolinite, smectite and illite being present, but had different chemical properties. The organic carbon content of cutans was higher than for matrix soil, while pH values and oxalate extractable/dithionate extractable iron (Feo/Fed) ratios were lower. Numerous SEM-EDS single point analyses of cutans and the plasma phase of the matrix soil indicated that the mean value of K concentration in cutans is greater than in matrix soil, and that the K concentration decreased with distance from cutan to matrix. Chemical extractions showed mean values of total K and latent exchangeable K were higher for cutans than for matrix soil, but both fixed K and exchangeable K values were the same for cutans and matrix soil. In a K adsorption/desorption experiment, 35% of K adsorbed by matrix soil could not be desorbed by 1 M NH4Ac. These results indicate that cutans are relatively enriched in K and may play an important role in determining available K and latent exchangeable K due to the special physical and chemical environments they provide in the soil
Microporosity of BIF hosted massive hematite ore, Iron Quadrangle, Brazil.
Massive hematite ore (MHO) is a special high-grade iron ore, used as lump ore in the process of obtaining direct reduction iron (DRI). The influence of porosity on the reducibility of MHO from the Capitão do Mato Mine (Iron Quadrangle, Brazil) was investigated using optical and scanning electron microscopes on drill core and open pit samples. Hematite is the main component of the samples and occurs as granular crystals (10 mum), microplates (1 mum) and euhedral martite (10 to 30 mum). Quartz, maghemite, kenomagnetite and goethite are minor components. Primary micropores (Å to 1 mum) are associated with microplaty crystals that fill cavities between granular hematite. Secondary micropores (Å to 5 mum) related to euhedral martite crystals, are the most important. The total porosity of weathered samples, measured using nitrogen adsorption and mercury injection, attains values up to 11%, whereas unweathered samples have a porosity less than 2.5%. Reducibility is strongly enhanced by porosity, but inhibited by structure (bedding)
Geochemical indices allow estimation of heavy metal background concentration in soils
Defining background concentrations for heavy metals in soils is essential for recognizing and managing soil pollution. However, background concentrations of metals in soils can vary naturally by several orders of magnitude. Moreover, many soils have also been subject to unquantifiable anthropogenic inputs of metals, in some cases, for centuries. Hence determination of heavy metal background concentrations in soils has to date been fraught with difficulty. Here we demonstrate that there are associations between the background heavy metal and Fe or Mn contents in soils which appear to be consistent for seven important heavy metals of environmental concern. The relationships are remarkably independent of both soil type and climatic setting. These observations provide the basis for a series of general equations from which it is proposed Southeast Asian including Australian, and possibly worldwide background concentrations for As, Cr, Co, Cu, Ni, Pb, and Zn in soils can be derived.R. E. Hamon, M. J. McLaughlin, R. J. Gilkes, A. W. Rate, B. Zarcinas, A. Robertson, G. Cozens, N. Radford and L. Bettena
Managing hostile subsoils in the high rainfall zone of south-western Australia
This report is designed to complement existing information on the management of crops in the High Rainfall Zone of south-western Australia and to identify limitations for crop production arising from the soil properties in this area
Universal Behavior of Lyapunov Exponents in Unstable Systems
We calculate the Lyapunov exponents in a classical molecular dynamics
framework. The system is composed of few hundreds particles interacting either
through Yukawa (Nuclear) or Slater-Kirkwood (Atomic) forces. The forces are
chosen to give an Equation of State that resembles the nuclear and the atomic
Equation Of State respectively near the critical point for liquid-gas
phase transition. We find the largest fluctuations for an initial "critical
temperature". The largest Lyapunov exponents are always positive and
can be very well fitted near this "critical temperature" with a functional form
, where the exponent is
independent of the system and mass number. At smaller temperatures we find that
, a universal behavior characteristic of an order
to chaos transition.Comment: 11 pages, RevTeX, 3 figures not included available upon reques
Quantum gate algorithm for reference-guided DNA sequence alignment
Reference-guided DNA sequencing and alignment is an important process in
computational molecular biology. The amount of DNA data grows very fast, and
many new genomes are waiting to be sequenced while millions of private genomes
need to be re-sequenced. Each human genome has 3.2 B base pairs, and each one
could be stored with 2 bits of information, so one human genome would take 6.4
B bits or about 760 MB of storage (National Institute of General Medical
Sciences). Today most powerful tensor processing units cannot handle the volume
of DNA data necessitating a major leap in computing power. It is, therefore,
important to investigate the usefulness of quantum computers in genomic data
analysis, especially in DNA sequence alignment. Quantum computers are expected
to be involved in DNA sequencing, initially as parts of classical systems,
acting as quantum accelerators. The number of available qubits is increasing
annually, and future quantum computers could conduct DNA sequencing, taking the
place of classical computing systems. We present a novel quantum algorithm for
reference-guided DNA sequence alignment modeled with gate-based quantum
computing. The algorithm is scalable, can be integrated into existing classical
DNA sequencing systems and is intentionally structured to limit computational
errors. The quantum algorithm has been tested using the quantum processing
units and simulators provided by IBM Quantum, and its correctness has been
confirmed.Comment: 19 pages, 13 figure
Inclusive Soft Pion Production from 12.3 and 17.5 GeV/c Protons on Be, Cu and Au
Differential cross-sections are presented for the inclusive production of
charged pions in the momentum range 0.1 to 1.2 GeV/c in interactions of 12.3
and 17.5 GeV/c protons with Be, Cu, and Au targets. The measurements were made
by Experiment 910 at the Alternating Gradient Synchrotron in Brookhaven
National Laboratory. The cross-sections are presented as a function of pion
total momentum and production polar angle with respect to the beam.Comment: 14 pages, 8 figure
Heated nuclear matter, condensation phenomena and the hadronic equation of state
The thermodynamic properties of heated nuclear matter are explored using an
exactly solvable canonical ensemble model. This model reduces to the results of
an ideal Fermi gas at low temperatures. At higher temperatures, the
fragmentation of the nuclear matter into clusters of nucleons leads to features
that resemble a Bose gas. Some parallels of this model with the phenomena of
Bose condensation and with percolation phenomena are discussed. A simple
expression for the hadronic equation of state is obtained from the model.Comment: 12 pages, revtex, 1 ps file appended (figure 1
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