The search for Rydberg matter: Beryllium

Results are presented from theoretical investigations of condensed excited states of beryllium by the Hartree-Fock method with allowance for the width of the atomic levels. It is shown that, during the excitation of a beryllium atom in the X-ray energy range, the 2p states split, the one-electron energy levels are shifted by unequal amounts, the 2s and 2p states mix at excitation energies of 10 and 14 Ry, and the atom is stabilized at energies higher than 6.7 Ry. In the optical range of excitation energies, a condensed excited state of beryllium with a lifetime on the order of 0.1 fs is revealed.     

Rates of litterfall and organic matter turnover at three South Australian indigenous forest sites

A quantitative study of the litterfall rate, litter mass and the organic carbon content of litter and soil at three South Australian low open-forests was made monthly for 2 years. The soil and dominant vegetation at the sites were similar, but the mean annual rainfall differed; 635, 690 and 1050 mm respectively at the ‘dry’, ‘medium’ and ‘wet’ sites. Mean annual litterfall at the dry, medium and wet sites was 114, 205 and 233 g m^?2 respectively, and the mean mass of the litter layer was 885, 1153 and 858 g m^?2 Leafy material formed 82% of the litterfall at each site and maximum fall occurred in the summer. Leafy material formed 64–68% of the three litter layers and there was no general pattern of seasonal change of mass. The data obtained were used to calculate the half-life (T_1/2 of the litter, the values were 5.4, 3.9 and 2.6 years respectively at the dry, medium and wet sites. The values from the medium and wet sites fit within the range previously recorded for other open-forests and low open-forests, but indicate an extremely slow rate of decomposition at the dry site, which was located close to open-scrubland. The amounts of organic carbon in the 0–8 cm layer of soil at the dry, medium and wet sites were 777, 928and 950 g m^-2 respectively. However, without a detailed investigation of the source of soil carbon, these values could only be used to show that the organic carbon store to a depth of 8 cm is equivalent to 9–15 times the annual litterfall input.     

Problems in the search for amino acids in lunar fines

In the search for amino acids in lunar fines, a major problem is the prevention of contamination from terrestrial sources, and the recognition of terrestrial contamination when it has occurred. Synthesis of amino acids conceivably could take place in the lunar module rocket exhaust, a possibility that has not been adequately ruled out. Amino acids could be shed from the astronauts suits, a possibility which has not been studied at all. Amino acids could also be introduced, at many stages of terrestrial manipulation, and during the analytical procedures employed. Hand contamination has qualitative and quantitative features that are characteristic and can be assessed. Precautions for elimination of hand and microbial contamination from glassware, reagents and water are proposed.A second major problem is the efficiency of recovery of amino acids added to lunar material, which is then subject to the complete analytical scheme. This necessitates the availability of lunar material to develop proper procedures.Besides the amino acids present in excess of blank values, it is necessary for the correct interpretation of any positive findings to know whether the amino acids are free or bound and optically inactive or active.The ion exchange chromatography and gas chromatography-mass spectrometry are procedures that complement each other. Both should be applied not only to the same sample but to the same preparations. To pit one method against the other is to risk losing the best analytical data.     

Ion-exchange chromatography in lunar organic analysis

Although ion exchange chromatography has been used in separating amino acids from mineral salts, quantitative recovery has not been possible for the basic amino acids or for subnanomole concentrations of amino acids.As an analytical tool for amino acid analysis, ion-exchange chromatography has made it possible to resolve a relatively complex mixture of amino acids in less than an hour with detection limits of less than 10^–12 moles of amino acids. Reasonable specificity for amino acids is achieved by multiple wavelength detection of the reaction product found with ninhydrin. Unequivocal specificity must be obtained in conjunction with other methods such as mass spectrometry.In the analysis of subnanomole levels of amino acids, it is necessary to carry both reagent blanks and low-level amino acid standards through the entire sample preparation step since both contamination and selective losses occur and must be monitored.     

Soil organic matter and the indigenous nitrogen supply of intensive irrigated rice systems in the tropics

Soil organic matter (SOM) has been proposed as an index of N supply in paddy soils although field validations are few. We evaluated the relationship between the indigenous N supply (N _i ) of the soil-floodwater system and soil organic carbon (SOC) or total N (N _t ) in surface soil of long-term fertility experiments (LTFEs) at 11 sites, in 42 farmer's fiels with similar soil type, and in the same field in ten consecutive rice (Oryza sativa L.) crops. The N _i was estimated by crop N uptake from plots without applied N (N _o plots) under otherwise favorable growth conditions. There was a tight linear correlation between yields and N uptake in N _o plots and tremendous variation in both parameters among LTFE sites, farmer's fields, and in the same field over time. Correlation between N _i and SOC or N _t explained little of this variation. Factors likely to contribute to the poor correlation were: (1) inputs of N from sources other than N mineralization of SOM in surface soil, (2) degree of congruence between soil N supply and crop demand, which is sensitive to soil drying, length of fallow, crop rotation, and residue management, and (3) differences in SOM quality related to intensive cropping in submerged soil. Better understanding of the processes governing the N _i of tropical lowland rice systems would contribute to the development of crop management practices that optimize utilization of indigenous N resources.     

The retention of organic matter in soils

The turnover of C in soils is controlled mainly by water regimes and temperature, but is modified by factors such as size and physicochemical properties of C additions in litter or root systems, distribution of C throughout the soil as root systems, or addition as litter, distribution of C within the soil matrix and its interaction with clay surfaces.Soil factors which retard mineralization of C in soils are identified from correlations of C contents of soils with other properties such as clay content and base status. The rate and extent of C mineralization depends on the chemistry of the added organic matter and interaction with clays of the microbial biomass and metabolites.The organomineral interactions are shown to depend on cation bridges involving mainly Ca in neutral to alkaline soils, Al in acid soils and adsorption of organic materials on iron oxide surfaces. The various organomineral interactions lead to aggregations of clay particles and organic materials, which stabilizes both soil structure and the carbon compounds within the aggregates.     

The Ultuna long-term soil organic matter experiment

In 1991, soil samples were taken from the long-term (40 years old) field trial at Ultuna in order to investigate soil P status and the distribution of its various forms. Among the treatments investigated, two were inorganic PK additions only – one to continuous fallow (PK-fallow) and the other to cropped fields (PK). There were also treatments amended with PK in combination with applications of straw, green manure composed of grass (GM), farmyard manure (FYM) or sewage sludge (SS). A total of 720, 720, 883, 1154, 1941 and 6617 kg P h^-1 had been supplied in the PK-fallow, PK, Straw, GM, FYM and SS treatments, respectively up to 1991. The soil P distribution was determined by step-wise fractionation using anion exchange resin (resin-P), sodium bicarbonate (bicarb-P), sodium hydroxide (hyd-P), and HCl (HCl-P). Finally, the soil was digested to obtain residual P (resid-P). The amendments resulted in a significant (p=0.05) enrichment of total P in soils relative to the initial value. A breakdown of the bicarb-P and hyd-P into inorganic P (P_i) and organic P (P_o) was manifested as considerable transformations within these P compartments compared with the initial values. Thus, total P_i (resin-P, bicarb-P_i, hyd-P_i, HC1-P, resid-P)/total P_o (bicarb-P_o, hyd-P_o) ratios markedly decreased in all treatments relative to control. The two P compartments were significantly and negatively (p =0.05) correlated. On average, the total P_o increase was about 380 mg kg^-1 (range 270–715). The results suggested that an equilibrium between P_i immobilization and P_o mineralization was difficult to attain under any of the experimental management regimes used, which exclude inorganic N application. The balance sheet calculations revealed P deficits ranging from about 10 to 60 kg ha^-1, indicating that some P had migrated to the subsoil.     

Aromatic and heteroatom-containing organic compounds in the lunar samples

The data concerning the indigenous organic compounds in the lunar samples has been consistent. The Apollo 11 sample appeared to be moderately contaminated, and most investigators found known terrestrial artifacts in these samples. The Apollo 12 data indicated that perhaps benzene and toluene were indigenous to the Moon at concentrations below 100 parts per billion. Other, more complex organic molecules (in particular of aromatic structure) might also be present, but in concentrations below 1 ppb. In general, the structural types reported have been relatively simple; perhaps indicating that what little organic chemistry occurs on the lunar surface can best be described as reactions between individual atoms of carbon, hydrogen, oxygen and nitrogen.     

In situ synthesis during organic analysis of lunar samples

In the development and application of extremely sensitive analytical techniques the need for extreme cleanliness and avoidance of contamination has been generally recognized and complied with in the organic analysis of lunar samples. Much less attention has been paid to the possibility of inadvertent synthesis of certain organic molecules from indigenous smaller organic or even inorganic constituents of the lunar material. At the part-per-billion level of detectability reactions proceeding even at very low yield can lead to detectable products. A particular area of concern should be the amino acid analysis since those substances are known to be formed by condensation of ammonia, cyanide and carbonyl compounds, all potential products of lunar material upon treatment with aqueous media.     

The responses of lake waters to organic matter additions

The increase of inorganic nitrogen subsequent to the addition of organic matter was investigated in replicate lake-water aliquots. Two experiments used freshly killed bacteria as the organic addition. In both, inorganic nitrogen in the water column increased only after a lag period following the organic addition, and only if the amount of organic matter added exceeded a threshold value. Two other experiments used freshly killed algae as the organic addition; in these, neither the lag period nor the threshold value were seen. A qualitative explanation for these observations is offered.     

The role of organic matter in soil manganese equilibrium

Summary Tests were conducted to determine the role of additions of fresh organic matter (ground cotton seed hulls) to an alluvial loam soil of pH 8 on manganese equilibrium. It was shown that organic matter has a reducing potential which, when added to the soil, resulted in a rapid and marked increase in exchangeable manganese. The reduction is enhanced by higher temperatures (21.1vs 37.7°C) and additions of water (field capacityvs air dry) and incubation periods up to 3 days. It is suggested that the shift in the soil manganese equilibrium, induced by such factors as waterlogging or anaerobic conditions, will be more pronounced when soils contain high levels of organic matter.Patterns of the standard deviations of sample exchangeable manganese data within treatments showed that the variance is highest in moist soil, lower concentrations of added organic matter, and at longer durations of incubation. Re-oxidation of manganese occurred at lower levels of added organic matter (2 and 4%) and extended incubation time (5 to 9 days).The investigation reported in this paper (67-10-36) is in connection with a project of the Kentucky Agricultural Experiment Station and is published by permission of the Director.     

Biodegradation of ferrihydrite-associated organic matter

The association of organic molecules with mineral surfaces is a major mechanism to stabilize soil organic matter against biodegradation. We performed microbial incubation experiments to quantify the mineralization of soil organic matter associated with ferrihydrite by adsorption and coprecipitation. Samples were produced using either water-extractable organic matter of a Podzol forest-floor layer (FFE) or a sulfonated lignin. Incubation was carried out with an inoculum extracted from the forest-floor layer under oxic conditions at pH 4.8 over 68 days. Our data show that the association with ferrihydrite stabilized the associated organic matter: the degradation of the polysaccharide-rich FFE was slowed down, while the degradation of lignin was inhibited. Since differences in the degradability of adsorbed and coprecipitated organic matter were small, we conclude that coprecipitation did not lead to a significant formation of microbial inaccessible organic matter domains in our experiments.     

Photo-oxidation of dissolved organic matter for trace metal analysis

Abstract

Photo-oxidation of dissolved organic matter in saline and non- saline samples is monitored by measurement of residual fluorescence intensity. For fulvic acids, the method has a detection limit of 0.005 mg C L^?1, and maximum photo-oxidation is achieved with H₂O₂ oxidant and a low-intensity UV source.