Distribution Of Various Fractions Research Articles

Influence of Integrated Nutrient Management on Fractions of Zinc and Its Uptake by Indian Spinach (Beta vulgaris L.)

ABSTRACT Zinc (Zn) availability can change with different organic amendments applied. The aim of this study was to evaluate the impact of farm yard manure (FYM) and vermicompost (VC) applied with or without chemical Zn fertilizer on dry biomass yield, Zn uptake by Indian spinach (Beta vulgaris L.), and distribution of various fractions of Zn in post-harvest soil. Results indicated that dry biomass yield and Zn uptake positively responded to the application of FYM or VC alone at 2% as well as in combination with Zn at 5 mg kg−1 through ZnSO4·7H2O. Integrated application of recommended dose of fertilizers (RDF)+2% VC+5 mg kg−1 Zn increased dry biomass yield and Zn uptake by 2.92- and 3.37-folds, respectively, over the control. Integrated application of RDF+2% FYM+5 mg kg−1 Zn was the best combination for increasing water-soluble and exchangeable Zn (WS&EX-Zn), carbonate-bound Zn (CAR-Zn), Fe- and Mn-oxide-bound Zn (FeMnOX-Zn), and organically bound Zn (OR-Zn) fractions. However, the preponderance of different Zn fractions remained the same in all the treatments, viz. WS&EX-Zn < FeMnOX-Zn < CAR-Zn < OR-Zn < Residual Zn (RES-Zn). All the Zn fractions were significantly and positively correlated with DTPA-extractable Zn, dry biomass yield, and uptake of Zn.

Deciphering the source contribution of organic matter accumulation in an urban wetland ecosystem

AbstractA better understanding of the organic matter (OM) dynamics is a key to successful wetland management. We established the radiocarbon chronology (14C) and vertical distribution of nitrogen (N), phosphorus (P), OM, and carbon to nitrogen ratio (C/N) in the sediment core retrieved from the Anchar Wetland, Kashmir Himalaya. The accelerator mass spectrometer (AMS) assisted 14C dating of the sediment core showed 14C age reversals related to occasional disturbances. The vertical distribution of various fractions revealed increased concentrations of organic carbon (OC), OM, and nutrients (N and P) in the upper part of the sediment core, largely related to increased anthropogenic inputs from the catchment areas during recent decades. Further, the low to high C/N ratio (1.3–36.4) suggests a combination of both the autochthonous and allochthonous inputs as the major contributors of OM to the wetland ecosystem. The linear regression model showed significant (p &lt; 0.05) positive and negative relationships among various analyzed parameters. Principal component analysis (PCA) resulted in three principal components (PCs) accounting for a cumulative variance of 83.6%. The PCA suggests that the primary production, human activities such as extraction of Lotus stems (Nadru) and fishing, and terrestrial inputs (sewage disposal and fertilizer runoff) are the major factors controlling the distribution of organic fractions and nutrients. This study provides important insights into the sources and distribution of sedimentary OM and nutrients crucial for assessing the risks of pollution and for adopting the socially, politically, and scientifically robust strategies for the management of wetlands.

Study of distribution of various fractions of Phosphorous as influenced by long term nutrient management practices in Vertisol

A long term field experiment was conducted at Instructional Farm of College of Agriculture, Indira Gandhi Agricultural University, Raipur, Chhattisgarh to evaluate the effect of long term nutrient management practices on distribution of various fractions of Phosphorous in Vertisol. The experiment was consisted 5 treatment replicated four times in a randomised block design. The treatments were T1 (control), T2 (GRD), T3 (YT 5t ha-1), T4 (YT 6t ha-1) and T5 (YT 6t ha-1 with FYM). Fertilizer prescription equation for rice developed in previous under STCR project as FN =4.05T-0.57SN-0.78 ON, FP = 1.46 T - 3.09 SP-0.31 OP and FK = 1.61 T - 0.10 SK -0.14 OK were used to calculating the fertilizer doses for yield targeted treatments. Initial soil value of phosphorus under different treatments was varied from 6.13 to 25.40 kg ha-1due to long term nutrient management practices. All the P fractions were significantly higher in T2 followed by T5, T4, T3 and lowest in T1. All P fractions (Saloid, Al, Red, Fe, and Ca P) were recorded higher values with the treatment T2 (GRD) due addition of a large amount of phosphorous applied in soil. The sequential order of dominance of different forms of phosphorus in Vertisol were “Ca-P > Red-P > Fe-P > Al-P >Saloid-P”. The percentage contribution of different fractions to the total P was in the order of “Ca-P > Red-P > Fe-P > Al-P >Saloid-P. The highest grain and straw yield were recorded in T5 (YT 6t ha-1 with FYM) followed by T4 (YT 6t ha-1), T2(GRD) and lowest in T1(control). Among different P fractions, Red-P was found the most important P fractions contributing toward grain yield with ‘R2’values 0.88.

Determining cadmium bioavailability in sediment profiles using diffusive gradients in thin films

Cadmium (Cd) uptake by plants or benthic organisms largely depends on its bioavailability in sediments, so it is necessary to understand Cd bioavailability for determining its ecological risks in riverine sediments. Pore water is easily disturbed during sample collection, indicating that there was a shortage of traditional methods for investigating Cd bioavailability. Here, sediment cores were collected from rivers, after which sequential extraction and diffusive gradients in thin films (DGT) method were employed to determine Cd potential bioavailability in the sediments and pore water. We found that Cd concentrations measured by DGT were lower than that in pore water profiles, and Cd distribution in various fractions changed remarkably. Pearson correlation analysis showed significant positive correlations between Cd concentrations measured by DGT and total Cd concentrations (r2 = 0.76), exchangeable and weak acid soluble fraction (r2 = 0.68), ferromanganese fraction (r2 = 0.72) and bound organic matter or oxidizable fraction (r2 = 0.54). However, the correlation was relatively low between Cd concentrations measured by DGT and that in pore water profiles (r2 = 0.26). These results demonstrated that DGT method could provide more accurate information of Cd bioavailability in sediment profiles than traditional methods.

Assessment of bioavailability of selenium in different plant-soil systems by diffusive gradients in thin-films (DGT)

Uptake of selenium (Se) by plants largely depend on the availability of Se in soil. Soils and plants were sampled four times within 8 weeks of plant growth in pot experiments using four plant species. Sequential extraction and diffusive gradients in thin-films (DGT) method were employed to measure Se concentrations in potted soils in selenite- or selenate-amended soils. Results showed that DGT-measured Se concentrations (CDGT−Se) were generally several folds higher for selenate than selenite amended soils, which were obviously affected by the plant species and the duration of their growth. For example, the folds in soil planted with mustard were 1.49–3.47 and those in soils planted with purple cabbage and broccoli, which grew for 3 and 4 weeks after sowing, were 1.06–2.14 and only 0.15–0.62 after 6 weeks of growth. The selenate-amended soil planted with wheat showed an extremely high CDGT−Se compared with selenite-amended soil, except the last harvest. Furthermore, minimal changes in CDGT−Se and soluble Se(IV) were found in selenite-amended soils during plant growth, whereas significant changes were observed in selenate-amended soils (p < 0.05). Additionally, Se distribution in various fractions of soil remarkably changed; the soils planted with purple cabbage and broccoli showed the most obvious change followed by wheat and mustard. Soluble Se(VI) and exchangeable Se(VI) were likely the major sources of CDGT−Se in selenate-amended soils, and soluble Se(IV) was the possible source of CDGT−Se in selenite-amended soils. In selenate-amended soils, soluble Se(VI) and exchangeable Se(VI) were significantly correlated with Se concentrations in purple cabbage, broccoli, and mustard; in wheat, Se concentration was significantly correlated only with soluble Se(VI) but not with exchangeable Se. CDGT−Se eventually became positively correlated with Se concentrations accumulated by different plants, indicating that DGT is a feasible method in predicting plant uptake of selenate but not of selenite.

Zinc Fractions and their Availability to Wetland Rice in Acidic Soils of Assam

Distribution of various fractions of soil zinc (Zn) and their relationships with soil properties in rice growing soils of Assam were studied with twenty five geo-referenced soil samples (0-30 cm) with variable Zn status from rice growing areas of Assam, representing 3 major soil orders viz., Entisol, Inceptisol and Alfisol. The distribution of different forms of Zn in rice soils revealed that water soluble and exchangeable Zn (WSEx-Zn) fraction in soils ranged from 0.32 to 1.92, complexed Zn (COMP-Zn) from 1.46 to 4.5, amorphous sesquioxide bound Zn from 1.30 to 6.21, crystalline sesquioxide bound Zn (CBD-Zn) from 0.45 to 2.25 and residual Zn (Res-Zn) from 101.7 to 285.2 mg kg-1 with mean values of 0.87, 2.71, 2.92, 1.12 and 186.98 mg kg-1, respectively. Residual Zn was the dominant fraction among all Zn fractions studied, which ranged from 101.7 to 285.2 mg kg-1 and the mean value was 186.9 mg kg-1. The WSEx-Zn, COMP-Zn, amorphous sesquioxide bound Zn, CBD-Zn and Res-Zn constituted 0.45, 1.57, 1.62, 0.63 and 95.7 per cent of total Zn. Multiple regression of physicochemical properties of soil with different Zn-fractions showed the highest R2 value (0.616) with COMP-Zn. Multiple regression of different Zn fractions with plant parameters showed the highest contribution of WSEx-Zn to plant Zn concentration (76.7%), Zn-uptake (63.0%) and dry matter yield (36.1%) of rice. Path coefficient analysis of different Zn-fractions with Zn-concentration in rice plant showed the highest direct effect (0.5610) of WSEx-Zn on Zn concentration and indirect effect of COMP-Zn (0.3731) and amorphous sesquioxide bound Zn (0.2508) via WSEx-Zn. Significant positive correlation was also observed between WSEx-Zn and plant Zn uptake (r=0.668**), plant Zn concentration (r=0.647**) and drymatter yield (r=0.401*), suggesting that water soluble plus exchangeable Zn fraction is of great importance in Zn nutrition of lowland rice. Major portion of Zn was in the residual fraction which contributed very little to plant uptake. Significant positive correlation among WSEx, organic complex and amorphous sesquioxide bound Zn indicated that they are possibly in dynamic equilibrium with each other.

Phosphorus speciation in the marine sediment of Kalpakkam coast, southeast coast of India.

A study was carried out at Kalpakkam coast to find out the distribution of various fractions of phosphorus (P) in the marine sediment during pre-northeast monsoon period. Samples were collected from ten locations covering ~80 km(2) of the inner-shelf region. Sedimentary parameters such as sand, silt, clay, and organic carbon percentage were analyzed in order to find out their relation with various P fractions. The sediment was found to be predominantly sandy in nature with low silt and clay content. Among all the fractions (loosely bound (LoP), calcium bound (CaP), iron bound (FeP), aluminum bound (AlP), and organic (OP)), CaP fraction constituted the largest portion (68.7%) followed by organic fraction (16.3%). The bioavailable P fractions ranged from 5 to 44% of the total P (TP) content. Relatively high LoP content was observed at the offshore locations with comparatively high mud percentage as compared with the near-shore locations. As FeP and AlP concentrations were directly proportional to the amount of fine-grain sediment, the low levels of these fractions found in this coastal area were therefore attributed to the sandy nature of the sediments. The order of abundance of the major forms of P in the surface sediments of Kalpakkam coast was as follows: CaP > OP > LoP > AlP > FeP.

Gram-scale fractionation of nanodiamonds by density gradient ultracentrifugation

Size is a defining characteristic of nanoparticles; it influences their optical and electronic properties as well as their interactions with molecules and macromolecules. Producing nanoparticles with narrow size distributions remains one of the main challenges to their utilization. At this time, the number of practical approaches to optimize the size distribution of nanoparticles in many interesting materials systems, including diamond nanocrystals, remains limited. Diamond nanocrystals synthesized by detonation protocols - so-called detonation nanodiamonds (DNDs) - are promising systems for drug delivery, photonics, and composites. DNDs are composed of primary particles with diameters mainly <10 nm and their aggregates (ca. 10-500 nm). Here, we introduce a large-scale approach to rate-zonal density gradient ultracentrifugation to obtain monodispersed fractions of nanoparticles in high yields. We use this method to fractionate a highly concentrated and stable aqueous solution of DNDs and to investigate the size distribution of various fractions by dynamic light scattering, analytical ultracentrifugation, transmission electron microscopy and powder X-ray diffraction. This fractionation method enabled us to separate gram-scale amounts of DNDs into several size ranges within a relatively short period of time. In addition, the high product yields obtained for each fraction allowed us to apply the fractionation method iteratively to a particular size range of particles and to collect various fractions of highly monodispersed primary particles. Our method paves the way for in-depth studies of the physical and optical properties, growth, and aggregation mechanism of DNDs. Applications requiring DNDs with specific particle or aggregate sizes are now within reach.

Fractions of Iron in Soil under a Long-Term Experiment and Their Contribution to Iron Availability and Uptake by Maize–Wheat Cropping Sequence

Soil and plant samples were collected from an ongoing long-term experiment (LTE) at the Indian Agricultural Research Institute farm, New Delhi, to study the distribution of various fractions of iron (Fe) and their contribution to availability and plant uptake in a maize–wheat sequence. The optimum dose-based treatments adopted for the study were nitrogen (N), nitrogen–phosphorus (NP), nitrogen–phosphorus–potassium (NPK), NPK + farmyard manure (FYM), NPK+ zinc (Zn), and control (no fertilizer or manure). Different fractions of Fe in the soil were sequentially extracted using different extractants. Diethylenetriaminepentaacetic acid (DTPA)–extractable Fe did not differ significantly among the treatments as a result of continuous cropping for more than three decades. The overall mean total iron (Fe) content varied from 2.36 to 2.61% under different treatments. Residual Fe constitutes a major portion of total Fe in all four layers of soil. The Fe associated with easily reducible Mn and organic matter contributed directly to DTPA-extractable Fe both in pre-maize and post-wheat soil. Residual Fe contributed directly to uptake Fe by maize and wheat crops.

Heavy-metal distribution in various types of soil aggregates

125 Many regions of the world being heavily polluted, the geochemical cycles of heavy metals in the biosphere are considerably affected by anthropogenic factors. Studies and assessment of environmental pollution with heavy metals have become an integral part of environmental protection problems. In this context, soil is of great interest as a deposition medium [1]. The behavior of heavy metals in soils has been widely studied [2-7], but the consideration of soils in terms of a physical model [8] limited the ability of researchers to elucidate the interactions of heavy metals with soil components. Many heavy metals (zinc, copper, molybdenum, manganese, cobalt, and others) are essential microelements for plants. Recent experimental results [9‐11] indicate that colloidal soil particles reside in the cells of a three-dimensional net of organic humus molecules. The gel structure of the soil can be considered as a humus gel reinforced by colloidal particles. Interacting with water, this reinforced humus gel (RHG) behaves as many polymers; it absorbs water and increases in volume, forming a unified organomineral gel network. This work studies the mechanism of binding of heavy metals by soils, gaining and analyzing data on the heavy-metal distribution in various fractions of soil macroaggregates. Test samples were taken from high-humus horizons of a cultured soddy-podzolic soil from the vicinity of the Klyazma River floodplain, a gray forest soil from Vladimir oblast, and Kursk chernozem. Air-dry soils were sieved into the following fractions (mm): >10, 7‐10, 5‐7, 3‐5, 2‐3, 1‐2, 0.5‐1, 0.25‐0.5, and <0.25. Fractionated samples were pestled in a mortar to particle sizes of less than 1 mm, divided

Assessment of soil particle redistribution on two contrasting cultivated hillslopes

The particle size distributions of surface soils from two cultivated silty fields (Moorfield and Railway South) in Herefordshire, UK, were assessed by sampling on 20-m grids across the fields. Moorfield (8 ha) had a uniform landscape sloping mainly in a North–South direction while Railway South (12 ha) had complex undulating landscape characteristics. Samples from 3 surficial layers were also taken at 3 landscape positions at Moorfield to investigate recent (within-season) soil particle redistribution. Size fractions were determined using chemical dispersion, wet sieving (to separate the sand fractions) and laser granulometry (for the finer fractions). The distribution of various fractions and the relationships between elevation and the various fractions suggest preferential detachment and movement of coarse to very coarse silt fractions (16–63 μm), which were found mostly at downslope or depositional areas. Upper slope samples had higher clay to fine silt (< 16 μm) contents than bottom slope samples. The upslope–downslope patterns of size fractions, particularly on uniformly sloping areas, of the 2 fields were similar and their deposited sediments were dominated by coarse silt fractions. Samples from 3 landscape positions at Moorfield became coarser from the less eroded summit, through the eroding side-slope to the bottom-slope depositional area. Within each of these landscape positions the top 0–2.5 cm layers were more enriched in coarse silt fractions than the bottom layers. The spatial patterns of soil particle size distributions in the 2 fields may be a result of sediment detachment and deposition caused by water erosion and tillage operations.

A method to estimate the distribution of various fractions of PM 10 in ambient air in the Netherlands

Eight rules based on measurements, model calculations, additional deductions and expert judgement have been devised for use in estimating the distribution and sources of various fractions of PM 10 in the Netherlands. As some of the underlying assumptions to these rules are debatable, they can be best characterized as “rules of thumb”. A brief rationale is given for each rule. Using these rules it is concluded that a previous expert judgement of a contribution of 20% from Dutch sources to PM 10 levels in the Netherlands is probably too low. Different values for the national contribution to the ambient PM 10 levels in the Netherlands have been evaluated. A contribution of 40–45% to PM 10 levels from Dutch sources is shown to meet two decisive criteria: (1) a reasonable ratio of PM 10 originating from national and foreign sources and (2) a reasonable ratio of the fine and coarse fractions of PM 10. Such a contribution also agrees with available data. This study shows that a higher national contribution to the ambient PM 10 levels implies a larger share of local emissions of coarse particles >2.5 μm than previously estimated. It appears that the original concept of a “blanket” of homogeneous PM 10 concentrations covering the Netherlands, a useful concept to describe the occurrence of shallow concentration gradients on geographical scales smaller than the country as a whole, has turned out to be more of a “patchwork quilt”. Although the measured concentration gradients are low (<20%), probably because the distribution of emission sources in a densely populated country like the Netherlands is fairly homogeneous, the chemical composition of PM 10 may differ spatially due to the contribution of local sources emitting aerosols in the coarser fraction of PM 10.

Unusual grain size effect on trace metals and organic matter in contaminated sediments

Grain size effect on trace metals (cadmium, copper, lead, zinc, and iron) and total organic content distribution in various fractions (<0.063, 0.063–0.105, 0.105–0.250, 0.250–0.500, and 0.500–1.000 mm) of contaminated sediment has been studied. Selective partitioning of the studied contaminants in sediment fractions was observed, with a minimum content in the fine sand fraction of grain size 0.125–0.250 mm. Anomalously high concentrations of trace metals and organic matter content in the medium and coarse sediment fractions (>0.250 mm) was explained by the formation of large agglomerates (clusters) during the generally recommended drying procedures. These large agglomerates, formed from smaller sediment fraction particles enriched by various contaminants kept on their large specific area by adsorption forces, have been observed in photographs of the medium and coarse sediment fractions only. The formed agglomerates consist of small particles cemented either by dissolved organic matter or by sea salts present in the marine sediment. The formation of such agglomerates should be taken into consideration when conducting metal contamination studies on sediments.

Soil Manganese: E Values, Distribution of Manganese‐54 among Soil Fractions, and Effects of Drying

AbstractThe Mn labile pool was determined in a wide range of United Kingdom soils, using 54Mn tracer and two different extractants, CaCl2 and DTPA. Good agreement was obtained between E values obtained by two different equilibration procedures in CaCl2, but for most soils the concentrations of CaCl2‐extractable Mn were considerably lower than the E‐values. Higher E‐values were obtained in DTPA than in CaCl2, indicating that the former dissolved some nonisotopically exchangeable Mn. The rate of disappearance of 54Mn from the soil solution, and its distribution in various fractions, differed greatly between the soils. Generally, the radioisotope labeled all the soil fractions determined, with the majority of 54Mn associated with the water‐soluble + exchangeable, organically bound and easily reducible oxide fractions. When the labeled soils were subjected to air and oven‐drying, net gains of 54Mn were observed in the water‐soluble + exchangeable, resistant and residual Mn fractions, with corresponding reductions in the easily reducible oxide fractions. Upon drying, native Mn increased in the water‐soluble + exchangeable and EDTA‐extractable fractions. Possible mechanisms for these changes are discussed.

Distribution of Free Fatty Acids in Milk as Affected by Heating

Radioactive eaprylie and oleic acids were used to determine their distribution in various fractions of raw and heated milk. Despite the difference in physical properties, both fatty acids were detected in all major components of milk. In particular, large amounts were associated with the serum proteins indicating that both acids may be involved in the reported losses of free fatty acids in heated milk.

Metabolism of Sarcina lutea IV. Patterns of oxidative assimilation

Freshly harvested or lyophilized cells of Sarcina lutea assimilate carbohydrate during the oxidation of glucose and a linear relationship exists between the glucose utilized and the carbohydrate deposited. The product appears to be a polymer composed of glucose units and it may be utilized in the absence of exogenous glucose. Experiments with [U- 14C] ★★ ★ [U- 14C] uniformly labelled with 14C. and [3,4- 14C 2]glucose show that 55% of the carbon atoms of glucose are assimilated without appreciable dilution, while the lower incorporation of radioactivity from [I- 14C]glucose reflects the formation of unlabelled hexose from this substrate via the pentosephosphate cycle. Assimilation of pyruvate or acetate does not yield polysacchride (or poly-β-hydroxybutyrate) and the assimilatory mechanism is shown by position-labelled substrates to depend on the tricarboxylic acid cycle. The carboxyl group of pyruvate is virtually eliminated while C-3 is incorporated to a greater extent than C-2; in the analogous case of acetate incorporation of C-2 exceeds that of C-I. The data indicate that glucose is not assimilated via pyruvate and support the previous observation that under the conditions employed glycolysis is not reversible from pyruvate to glucose. On the other hand, polysaccharide formation from glycerol shows reversibility from triose, or an alternative route from triose to glucose. Comparisons are made of the distribution in various fractions of the cell of the radioactivity assimilated from [U- 14C]glucose, [3- 14C]pyruvate and [2- 14C]acetate.