浅论数据备份技术

数据备份是数据存储中一个非常重要的环节,实时备份系统是保证企业数据安全性与完整性的关键所在,而如何构建企业的实时备份系统是一个复杂的系统工程,本文介绍了目前最常见的四种备份系统结构。     

The effect of low-molecular-weight organic acids and inorganic phosphorus concentration on the determination of soil phosphorus by the molybdenum blue reaction

Low-molecular-weight organic acids play an important role in the mobilization of soil phosphorus (P). The molybdate blue colorimetric method, based on the formation of P molybdenum blue compound, is commonly used for analysis of phosphate in soil and environmental samples. However, some organic acids can act as a ligand to bond with molybdenum acid, which subsequently interfere with the colorimetric reaction. The recoveries of P were inhibited by the addition of oxalic (>2 mM) and citric acids (>3 mM) both in standard P solutions and soil extracts, but formic and maleic acids did not interfere with the P determination. The inhibition of oxalic and citric acids on P recovery remained even at higher level of P (up to 100 μg P 100 ml⁻¹) though such interferences decreased by increasing P concentration. Comparison between oxalic and citric acids revealed the more pronounced interference by the addition of oxalic acid. The results suggested that the interference of organic acids with P determination is related to the types of organic acids and the ratio of organic acid ligands to P anions in the solutions. Thus, analysis of P using the molybdate blue colorimetric method should be undertaken cautiously in the presence of relative strong ligands like oxalic and citric acids.     

Specific and non-specific adsorption of inorganic ions

The authors reported that the relative bonding strength between ligand of soil colloid surface and cations could be obtained easily by the measurement of MCSA, and that the MCSA corresponded to the constant of Langmuir's adsorption isotherm equation.

The relative bonding strength of cations with respect to kaolinitic soil clay at pH 6 was, Cr³⁺>Fe³⁺, Al³⁺>Ga⁸⁺>Cu⁸⁺>Pb²⁺>Y³⁺, La³⁺>Mn²⁺>Ni²⁺, Co²⁺> Zn²⁺>Sr²⁺, Mg²⁺>NH⁴⁺, K⁺, and with respect to colloid with humus coating, Y³⁺, La³⁺>Pb²⁺>Cu²⁺, and the other orders were same.

The solubility of cations in soil colloid aqueous dispersion system was calculated from the values of MCSAs, and considered as follows, Y³⁺, La³⁺, Cu³⁺, Pb³⁺, Mn²⁺, Ni²⁺, CO²⁺: concentration in soil solution and soil geochemical mobility may be regulated by the specific adsorption reaction, Zn²⁺, Mg²⁺, Sr²⁺, K⁺, NH⁴⁺: concentration in soil solution and soil geochemical mobility may be regulated by the non-specific adsorption reaction, but at neutral to alkaline condition, Zn²⁺ and Mg²⁺ may specifically adsorb on soil, clays, Fe³⁺, Cr³⁺, Al³⁺, Ga³⁺: concentration in soil solution and soil geochemical mobility may be regulated by the solubility of their oxide hydrates.     

Testing a mechanistic model. II. The effects of time and temperature on the reaction of zinc with a soil

Samples of a soil were mixed with zinc nitrate solutions and incubated from 1 to 30 days at temperatures from 4 to 60°C. The solution concentration of zinc, which would not have changed on brief mixing with the soil at 25°C, was measured. Background electrolytes for this measurement of null-point concentration were both calcium and sodium nitrate. The effect of the temperature at which null-point concentration was measured was also investigated. After incubation with zinc nitrate, desorption of zinc, and sorption of further zinc, were measured. Null-point concentration of zinc decreased with increasing period of incubation, with the rate of decrease greatest at high temperatures of incubation. The effects of both temperature and time were closely described by a model which postulated an initial rapid adsorption of ZnOH⁺ ions onto heterogenous charged surfaces, followed by a diffusive penetration. Increasing the temperature of incubation increased the rate of diffusive penetration and led to low solution concentrations. In contrast, increasing the temperature at which null-points were measured increased the concentration of ZnOH⁺ ions. This was shown to be consistent with a change in position of the equilibrium of the initial, rapid, adsorption reaction. Curves for desorption of zinc were continuous with curves for sorption of further zinc, but neither desorption nor further sorption coincided with the position of the curves relating retention of previously added zinc to concentration. This result was consistent with the model and occurred because desorption must reverse diffusive penetration. However, the model under-predicted the magnitude of both desorption and sorption of further zinc. Desorption in calcium solutions was greater than in sodium solutions, even when the solution concentration of zinc approached zero. This was consistent with exchange diffusion of calcium ions for some of the penetrated zinc.     

Effects of temperature,glucose and inorganic nitrogen inputs on carbon mineralization in a Tibetan alpine meadow soil

High levels of available nitrogen (N) and carbon (C) have the potential to increase soil N and C mineralization. We hypothesized that with an external labile C or N supply alpine meadow soil will have a significantly higher C mineralization potential, and that temperature sensitivity of C mineralization will increase. To test the hypotheses an incubation experiment was conducted with two doses of N or C supply at temperature of 5, 15 and 25 °C. Results showed external N supply had no significant effect on CO₂ emission. However, external C supply increased CO₂ emission. Temperature coefficient (Q₁₀) ranged from 1.13 to 1.29. Significantly higher values were measured with C than with N addition and control treatment. Temperature dependence of C mineralization was well-represented by exponential functions. Under the control, CO₂ efflux rate was 425 g CO₂–C m^?2 year^?1, comparable to the in situ measurement of 422 g CO₂–C m^?2 year^?1. We demonstrated if N is disregarded, microbial decomposition is primarily limited by lack of labile C. It is predicted that labile C supply would further increase CO₂ efflux from the alpine meadow soil.     

Organic and inorganic phosphate interactions with soil hydroxy-interlayered minerals

Background  

Even though extensive work has been done on P interactions with free Al- and Fe-hydroxide minerals, limited or no information exists on sorption/desorption processes of organic and inorganic phosphate forms with soil hydroxy-interlayered minerals.     

The effect of crop residue incorporation date on soil inorganic nitrogen, nitrate leaching and nitrogen mineralization

 Delaying cultivation and incorporation of arable crop residues may delay the release of NO₃ ^– and hence reduce leaching. The objective of this study was to investigate the effect of timing of cultivation on the mineralization and leaching of NO₃ ^– from an arable crop residue. Overwinter N leaching and periodic measurements of soil inorganic N were combined to estimate net N mineralized after ploughing a crop residue into a free-draining loamy sand soil in central England on six dates from June 1994 to January 1995. The crop residue was whole green barley with approximately 2% N. N leaching in the two following winters was increased by the addition of crop residues. Early residue application also tended to increase N leached in the first winter, largely as a consequence of relatively large losses early in the drainage period. Thus, early incorporation of crop residues presents a greater leaching risk. The amount of N leached in the second (drier) winter was similar for all dates of incorporation. At the end of the first winter, inorganic N derived from the crop residue was greatest for earlier additions: June (40% N applied) > September (30% N applied) > August (20% N applied) > October (19% N applied) > November (11% N applied) > January (3% N applied). However, at the end of the experiment, there was no evidence that the residues which had mineralized least by the end of the first winter had, to any significant degree, caught up, and this was confirmed by the parameters of the equation for first-order decomposition in thermal time. These results indicate that the effect of temperature, particularly in the early stages of residue mineralization, is complex and interacts with other soil processes in terms of the fate of the N mineralized. Received: 19 July 1999     

Testing a mechanistic model. I. The effects of time and temperature on the reaction of fluoride and molybdate with a soil

A mechanistic model that had been developed to describe the reaction of phosphate with soil was applied to the reactions of fluoride and molybdate with soil. The model assumes that: there is an initial adsorption reaction between ions and charged surfaces; that the surfaces are not uniform in their properties; and that the initial adsorption is followed by diffusive penetration. The model was developed beyond that previously published to permit the rate of the initial adsorption reaction to be included. The model reproduced the effects of solution concentration, and of increasing period and temperature of incubation, on the retention of both fluoride and molybdate. Increasing the temperature of incubation increased the retention, or decreased the solution concentration, and this was reproduced by the effect of temperature on the rate of diffusive penetration. Desorption of fluoride was also reproduced. This supports the argument that slow desorption is mostly due to the need to reverse the diffusive penetration. After incubation at constant temperature, increasing the temperature at which solution concentration of molybdenum was measured, increased the concentration. The direction of this effect of temperature was also reproduced. It arises because of the effect of temperature on the position of the equilibrium between adsorbed molybdate (in the strict sense of the term) and molybdate in solution.     

外源营养物质对表征土壤质量的生物学指标的影响

土壤微生物指标(土壤微生物组成和多样性、土壤微生物生物量、土壤微生物活性)、土壤酶活性和土壤动物是表征土壤质量的三大重要生物学指标。这些指标极易受土壤环境因素和人为活动的影响。诸如土壤水分、温度、耕作制度以及外源有机、无机物质等均对它们有较大的影响。本文就外源有机、无机营养物质对上述生物学指标的影响进行了综述。     

The reaction between phosphate and dry soil. II. The effect of time, temperature and moisture status during incubation on the amount of plant available P

Subterranean clover was grown in pots in which the only source of phosphate (P) was from bands of soil which had been incubated with P for a range of times, and at different temperatures, when either moist or air-dry. The effectiveness of these incubated soils in supplying P to plants decreased with time of incubation. Effectiveness decreased after air-dry incubation, though not as quickly as after moist incubation. These results indicate that air-dry storage of soil samples is to be avoided if the samples are to be assessed for their ability to supply P to growing plants. They also indicate that the cost-saving to Australian farmers, derived from applying phosphate prior to the start of the growing season, may be balanced or even outweighed by a loss in fertilizer effectiveness due to the reaction between P and the soil in the weeks prior to germination of seed.     

Evaluation of methods for soil inorganic nitrogen analysis

Abstract

This study determined the effects of soil preservation methods on inorganic nitrogen (N) analysis and evaluated methods of soil inorganic N analysis. Soils were preserved by oven‐drying at 55'C, air‐drying at 27°C, and freezing at ‐ 7°C. Inorganic N results were compared with initial N levels prior to imposing preservation treatments. Soil preservation effects on ammonium‐nitrogen (NH₄ ⁺‐N) were not consistent across soil types. Soil nitrate‐nitrogen (NO₃ ^‐‐N) levels after air‐drying and freezing compared most favorably with initial levels indicating that both are acceptable methods of soil inorganic‐N preservation. Levels of NH₄ ⁺‐N averaged across soils were 3.9 mg/kg for steam distillation, 4.2 mg/kg for sodium salicylate‐hypochlorite, and 3.7 mg/kg for indophenol blue. When compared with steam distillation averaged across soils, NO₃ ^‐‐N for cadmium‐copper (Cd‐Cu) reduction was 4 mg/kg greater, followed by nitrate electrode at 3 mg/kg, and salicylic acid at 2 mg/kg. Recovery of added N ranged from 83.3 to 94.8% for the NH4+‐N methods and from 74.8 to 112.4% for the NO₃ ^‐‐N methods with the nitrate electrode averaging 98.3%.     

Ammonium and nitrate influence on artichoke growth rate and uptake of inorganic ions

Artichoke plants (Cynara scolymus L.) were grown in a growth chamber in a modified Hoagland solution for seven weeks to determine the influence of ammonium:nitrate (NH₄:NO₃) ratio (100:0, 70:30, 30:70 and 0:100) on growth, water use, and the uptake of nitrogen (N) and inorganic anions and cations. Typical pH changes were recorded: the nutrient solution became acidified with NH₄ or NH₄:NO₃ nutrition; pH increased when NO₃ was the only N source. Ammonium‐fed plants (100:0 ratio) were stunted, with signs of marginal leaf necrosis, progressive wilting of leaves and poor root growth. After 49 days, leaf area was 77, 998, 2,415, and 1,700 cm² and dry weight was 1.0, 12.9, 38.0, and 26.0 g/plant, with NH₄:NO₃ 100:0, 70:30, 30:70, and 0:100, respectively. Leaf area ratio (LAR) was lower in plants supplied solely with NO₃ than in those with mixed NH₄‐NO₃. Increasing NO₃‐N percentage in the nutrient solution increased water use efficiency (WUE): 623, 340, and 243 mL of water were necessary to produce 1 g of dry matter in 100:0, 70:30, 30:70 or 0:100 NH₄:NO₃ ratio, respectively. Increasing NO₃ from 0 to 100% of the total N supplied in the nutrient solution, the shoot content of inorganic cations increased on an equivalent basis by 30% and organic anions (estimated by the difference between inorganic anions and inorganic cations) increased by 2.3 times. These results suggest that leaves are the most important site of NO₃ assimilation in artichoke. By increasing NH₄ percentage in the nutrient solution, the tissue content of inorganic anions was generally increased, except for NO₃, and the same figure was observed for the percentage of reduced N. Results from this study suggest that NO₃ is the N‐form preferred by artichoke.     

Assessment the effect of homogenized soil on soil hydraulic properties and soil water transport

Soil hydraulic properties play a crucial role in simulating water flow and contaminant transport. Soil hydraulic properties are commonly measured using homogenized soil samples. However, soil structure has a significant effect on the soil ability to retain and to conduct water, particularly in aggregated soils. In order to determine the effect of soil homogenization on soil hydraulic properties and soil water transport, undisturbed soil samples were carefully collected. Five different soil structures were identified: Angular-blocky, Crumble, Angular-blocky (different soil texture), Granular, and subangular-blocky. The soil hydraulic properties were determined for undisturbed and homogenized soil samples for each soil structure. The soil hydraulic properties were used to model soil water transport using HYDRUS-1D.The homogenized soil samples showed a significant increase in wide pores (wCP) and a decrease in narrow pores (nCP). The wCP increased by 95.6, 141.2, 391.6, 3.9, 261.3%, and nCP decreased by 69.5, 10.5, 33.8, 72.7, and 39.3% for homogenized soil samples compared to undisturbed soil samples. The soil water retention curves exhibited a significant decrease in water holding capacity for homogenized soil samples compared with the undisturbed soil samples. The homogenized soil samples showed also a decrease in soil hydraulic conductivity. The simulated results showed that water movement and distribution were affected by soil homogenizing. Moreover, soil homogenizing affected soil hydraulic properties and soil water transport. However, field studies are being needed to find the effect of these differences on water, chemical, and pollutant transport under several scenarios.     

The effect of preplant nitrogen and soil temperature on yield and nitrogen accumulation of alfalfa 1

Abstract

Recommendations for the use of preplant N in alfalfa establishment are controversial. Growth chamber experiments were conducted to examine the effect of preplant N and soil temperature on yield and N accumulation of alfalfa (Medicago sativa L.). Alfalfa was grown in river sand at three day/night soil temperatures (18/12°C, 24/16°C, and 27/21°C), and at five levels of preplant N (0, 10, 20, 40, 80 kg ha^?1). At 18/12°C, 40 kg ha^?1 preplant N resulted in a 69% increase in shoot dry matter yield. Dry matter and N accumulation rates were greatest at 40 and 80 kg ha^?1. Preplant N effects on dry matter and N accumulation at 18/12°C were expressed primarily between the early bud and early flowering stages. Assessment of soil temperature and soil N availability is necessary to determine the potential for a yield response of alfalfa to preplant N.     

Natural N abundances of inorganic nitrogen in soil treated with fertilizer and compost under changing soil moisture regimes

This study was conducted to examine whether the applications of N-inputs (compost and fertilizer) having different N isotopic compositions (δ¹⁵N) produce isotopically different inorganic-N and to investigate the effect of soil moisture regimes on the temporal variations in the δ¹⁵N of inorganic-N in soils. To do so, the temporal variations in the concentrations and the δ¹⁵N of NH₄⁺ and NO₃⁻ in soils treated with two levels (0 and 150 mg N kg⁻¹) of ammonium sulfate (δ¹⁵N=−2.3‰) and compost (+13.9‰) during a 10-week incubation were compared by changing soil moisture regime after 6 weeks either from saturated to unsaturated conditions or vice versa. Another incubation study using ¹⁵N-labeled ammonium sulfate (3.05 ¹⁵N atom%) was conducted to estimate the rates of nitrification and denitrification with a numerical model FLUAZ. The δ¹⁵N values of NH₄⁺ and NO₃⁻ were greatly affected by the availability of substrate for each of the nitrification and denitrification processes and the soil moisture status that affects the relative predominance between the two processes. Under saturated conditions for 6 weeks, the δ¹⁵N of NH₄⁺ in soils treated with fertilizer progressively increased from +2.9‰ at 0.5 week to +18.9‰ at 6 weeks due to nitrification. During the same period, NO₃⁻ concentrations were consistently low and the corresponding δ¹⁵N increased from +16.3 to +39.2‰ through denitrification. Under subsequent water-unsaturated conditions, the NO₃⁻ concentrations increased through nitrification, which resulted in the decrease in the δ¹⁵N of NO₃⁻. In soils, which were unsaturated for the first 6-weeks incubation, the δ¹⁵N of NH₄⁺ increased sharply at 0.5 week due to fast nitrification. On the other hand, the δ¹⁵N of NO₃⁻ showed the lowest value at 0.5 week due to incomplete nitrification, but after a subsequence increase, they remained stable while nitrification and denitrification were negligible between 1 and 6 weeks. Changing to saturated conditions after the initial 6-weeks incubation, however, increased the δ¹⁵N of NO₃⁻ progressively with a concurrent decrease in NO₃⁻ concentration through denitrification. The differences in δ¹⁵N of NO⁻₃ between compost and fertilizer treatments were consistent throughout the incubation period. The δ¹⁵N of NO₃⁻ increased with the addition of compost (range: +13.0 to +35.4‰), but decreased with the addition of fertilizer (−10.8 to +11.4‰), thus resulting in intermediate values in soils receiving both fertilizer and compost (−3.5 to +20.3‰). Therefore, such differences in δ¹⁵N of NO₃⁻ observed in this study suggest a possibility that the δ¹⁵N of upland-grown plants receiving compost would be higher than those treated with fertilizer because NO₃⁻ is the most abundant N for plant uptake in upland soils.     

The impacts of inorganic nitrogen application on mineralization of C-labelled maize and glucose, and on priming effect in saline alkaline soil

Organic matter dynamics and nutrient availability in saline alkaline soil of the former lake Texcoco will determine the success of a planned reforestation program. Uniformly labelled ¹⁴C-maize (MAI-treatment) and glucose (GLU-treatment) with or without 200 mg  kg⁻¹ soil (MAI-N treatment and GLU-N treatment, respectively) were added to soils with electrolytic conductivity (EC) 56 dS m⁻¹ (soil A) and 12 dS m⁻¹ (soil B) to investigate the importance of N availability on decomposition of organic material. Production of CO₂ and and inorganic N dynamics were monitored. The amount of ¹⁴C-glucose mineralized increased 1.8-times in the soil A, but had no effect in the soil B when 200 mg  kg⁻¹ soil was added, while the amount of ¹⁴C-maize mineralized increased 1.7 and 1.3-times when 200  kg⁻¹ soil was added in the soils A and B, respectively. Application of increased priming effect 3.7-times in the MAI-treatment of the soil A and 3.4-times in the GLU-treatment, while in the soil B the increase of priming effect was 4.1-times in the MAI-treatment and 3.7-times in the GLU-treatment. Of the 200 mg  kg⁻¹ added to both soils less than 10 mg NH₃-N kg⁻¹ was volatilized within one day, while 22 and 44 mg  kg⁻¹ soil was fixed on the soil matrix in the soil A and the soil B, respectively. Therefore more than 100 mg −N kg⁻¹ was immobilized into the microbial biomass within the first day. Concentration of nitrite increased sharply in all the treatments of soil A at the onset of the incubation followed by a decrease. A similar pattern was observed in the GLU-N and MAI-N treatments of the soil B, but not in the other treatments. A decrease in concentration of was observed in both soils followed by an increase in the MAI-N and GLU-N treatments of the soil B. It was found that application of had a stimulating effect on the decomposition of maize and glucose, and on the priming effect, while assimilatory reduction of resulted in an increase of in the soil A, and nitrification in the soil B.     

A temperature correction procedure for field-based soil denitrification experiments

Abstract. An equation is developed to permit temperature correction (to some chosen reference temperature) for field-based soil columns that measure the depletion of nitrate in the water column above a soil layer where denitrification occurs. The derivation is based on the assumption that the overall nitrate depletion is diffusion controlled by the nitrate flux from the water column into the soil and the soil denitrification obeys Michaelis-Menten kinetics. The expression is tested on results from a large soil column maintained in a greenhouse where natural temperature cycling occurred.     

Immobilization of soil copper using organic and inorganic amendments

This experiment aimed to immobilize Cu in polluted agricultural soils via the application of agrochemicals to reduce its bioavailability to plants. A greenhouse pot experiment was established using a Cu contaminated vineyard topsoil collected from a farm in Greece. The soil was mixed with inorganic [i.e., zeolite (Z), Al‐oxide (AX), Mn‐oxide (MX), and phosphate rock (PR)] as well as organic amendments [i.e., activated charcoal (AC), commercial peat soil material (CP), and compost from olive oil processing wastes (COW)] with an application rate of 2.5% and cultivated by corn (Zea maize). After plant harvesting, Cu was measured separately in the aboveground biomass and roots, respectively, whereas the soil samples were analyzed for DTPA‐extractable and geochemical fractions of Cu (soluble + exchangeable fraction, sorbed and carbonate fraction, Fe‐/Mn‐oxides fraction, and organic fraction). The immobilizing agents, except MX, reduced the soluble plus exchangeable Cu in the treated soil. The lowest concentrations of the soluble plus exchangeable Cu occurred in the soil amended with AC followed by CP, AX, COW, PR, and Z, respectively. The amendments decreased the uptake of Cu by corn. Concentrations of Cu were between 11 and 38% lower in the above ground biomass and 19 and 48% lower in the roots than the control. The organic amendments were more effective than the inorganic additives. The AC was the most effective organic additive and AX was the most effective inorganic amendment.     

PAM施用方式对土壤水热及玉米生长的影响

为了探寻PAM在玉米生产中的最佳施用方式,在河套灌区玉米播种时,以不施PAM为对照,研究PAM沟施、混施、撒施、穴施对土壤水分、土壤温度和玉米生长的影响。结果表明:1)在玉米生长的不同时期,PAM都可提高土壤水分,特别是在干旱的玉米抽雄吐丝期、灌浆期具有显著作用;2)PAM可延缓玉米幼苗期、三叶期的土壤温度回升,抑制玉米幼苗生长;3)从玉米拔节期开始,PAM可促进玉米生长,在玉米抽雄吐丝期、灌浆期效果最为显著;4)PAM沟施、混施、撒施、穴施的玉米产量分别较对照提高30.6%、39.3%、40.2%和31.7%,水分利用效率分别提高18.97%、25.43%、29.69%和20.46%,水分产出率分别提高31.36%、40.71%、42.15%和32.32%;5)在河套灌区,PAM撒施是玉米播种时相对适宜的施用方法。