Search

We aimed to elucidate the effects of decreases in nitrogen (N) inputs on N budgets and soil acidity in N saturated forests in Tokyo, Japan using new analysis and comparison to sampling data collect...

We investigated the physicochemical properties of starches extracted from 8 lotus (Nelumbo nucifera Gaertn.) rhizomes harvested in different months (September 2012 to May 2013). The physicochemical properties of the lotus starches depended on the harvest date. The peak viscosity (PV) in the Rapid Visco-Analyser analysis, and the viscosity at 65 °C (V65) in the rotational viscometer analysis were significantly lower in SEP starch (extracted from the September-harvested sample) than in the other lotus starches. The Spearman’s rank correlation coefficients of potassium ion (K) content vs. V65 and of K content vs. PV were 0.905 and 0.714, respectively, indicating that potassium ions are important for expressing the pasting properties of lotus starch. Principal component analysis suggested that the potassium, magnesium, calcium, and phosphorus contents are important for displaying both the pasting and gelatinization properties of the lotus starches. Meanwhile, the cluster analysis revealed that physicochemical properties of the SEP starch were different from those of the starches harvested in other months.

In Asian countries, paddy rice ( Oryza sativa ) has been cultivated as a main crop for many years, but cesium uptake by rice has only been studied recently. As a result, the effect of land use on cesium uptake by rice is not well understood, and there is little information about the interaction of cesium with alkali metals in the rice–soil system. The objective of this study was to elucidate the stable cesium (Cs), potassium (K), and rubidium (Rb) levels in rice cultivated under paddy and upland conditions and in the soil (a Hapludept). We cultivated 13 rice cultivars (temperate and tropical japonica ) under both conditions, and determined the concentrations of Cs, K, and Rb in brown rice and soil (total, exchangeable, and water-soluble fractions) by means of inductively coupled plasma mass spectrophotometry and atomic absorption spectrophotometry. We found that the soil concentrations of water-soluble Cs, K, and Rb were higher under upland conditions than paddy conditions, and Cs and Rb concentrations in brown rice were also higher under upland conditions. The upland conditions may increase soil ion concentrations by water evaporation, and the higher water-soluble Cs and Rb concentrations would increase their concentrations in brown rice. However, more K accumulated in brown rice under paddy conditions. This suggests that the roots absorbed K rather than Cs and Rb from the soil mainly by means of ion diffusion, because paddy conditions would increase ion diffusion but not the soil ion concentration. We conclude that the land use (here, paddy and upland conditions) changed the Cs, K, and Rb levels in the brown rice and soil by different mechanisms because root uptake of these elements would be different.

Wildfires and prescribed burning can affect both the quality and the quantity of organic matter in soils. In this study, we investigated qualitative and quantitative changes of soil humic substances in two different soils (an Entisol from a paddy field and an Inceptisol from a cedar forest) under several controlled heating conditions. Soil samples were heated in a muffle furnace at 200, 250, or 300 °C for 1, 3, 5, or 12h. The humic acid and fulvic acid contents of the soil samples prior to and after heating were determined. The degree of darkness, elemental composition, carbon and nitrogen stable isotope ratios, (13)C nuclear magnetic resonance spectra, and X-ray diffraction patterns of humic acids extracted from the soils before and after heating were measured. The proportion of humic acids in total carbon decreased with increasing heating time at high temperature (300 °C), but increased with increasing heating time at ≤ 250 °C. The degree of darkness of the humic acids increased with increasing heating time and temperature. During darkening, the H/C atomic ratios, the proportion of aromatic C, and the carbon and nitrogen stable isotope ratios increased, whereas the proportions of alkyl C and O-alkyl C decreased. X-ray diffraction analysis verified that a stacking nanostructure developed by heating. Changes in the chemical structure of the humic acids from the heated soils depended on the type of soil. The major structural components of the humic acids from the heated Entisol were aromatic C and carboxylic C, whereas aliphatic C, aromatic C, and carboxylic C structural components were found in the humic acids from the heated Inceptisol. These results suggest that the heat-induced changes in the chemical structure of the humic acids depended on the source plant.

Humic substances are ubiquitous in the environment. The development of models for their chemical structure can be expected to improve our understanding of their environmental behavior. In this study, we used X-ray diffraction (XRD) to develop models for the stacking nanostructure of 12 humic acids (HAs) extracted from Japanese Andisols, Inceptisols and Entisols. In the XRD profiles of the HAs, the γ band, which was attributed to aliphatic side chains, and the 002 band were separated by means of curve fitting with the Voigt function. The interlayer spacing of the carbon (C) planes (d002) and the mean thickness of the stacking nanostructure along the c axis (Lc) were calculated from the position of the peak for the 002 band and the full width at half maximum by means of Bragg’s and Scherrer’s equations, respectively. The average number of C planes in the stacking nanostructure (Nc) was estimated from d002 and Lc. The Lc and Nc values ranged from 1.04 to 1.84 nm and from 3.01 to 5.40, respectively. T...

To relate the isotopic composition of soil humic acids (HAs) to their source plants and their degree of humification (as indicated by the degree of darkening), as well as to soil type, we determined the stable isotope ratios for carbon (δ13C) and nitrogen (δ15N) of HAs extracted from 26 virgin soil samples (14 Andisols and 12 non-Andisols) and from leaf samples from ten C3 plants and seven C4 plants. The high absorption coefficients (estimated at 600 nm for 1% solutions), low hydrogen and nitrogen contents, low H/C ratios, low alkyl C and O-alkyl C contents, high O/H and C/N ratios, high aryl C contents, and high aromaticity of the Andisol HAs indicated a high degree of humification. The δ13C and δ15N values of the non-Andisol HAs increased along with the progression of humification of C3 plant-derived HAs. A significant correlation was observed between the δ15N and δ13C values of the non-Andisol HAs, but not for the Andisol HAs. Most of the Andisol HA δ13C values were higher than the highest non-Andisol HA δ13C value, and δ13C values were distributed between the δ13C values for the C3 and C4 plants. The contributions of C4 plant-derived carbon to total Andisol HA carbon (CRC4) are usually calculated on the assumption that the δ13C values are not substantially altered during the decomposition of plant materials and the formation of soil organic matter. However, if 13C enrichment occurs during organic matter decomposition, CRC4 will be overestimated. Therefore, we suggest a new method to calculate CRC4 values of Andisol HAs with a correction for isotopic fractionation associated with microbial degradation; the corrected CRC4 values ranged from − 5% to 58% and were approximately 22% lower than the uncorrected values.

Phosphate rocks (PRs) can be a source of cadmium pollution in soil and food chain. PRs are mainly used for the manufacturing of phosphate fertilizers. The characteristics of PRs with special reference to cadmium, which are important phosphate fertilizer source, were investigated. In my field of study, PR of USA (PR1: from Wyoming, PR2: from Florida PR3: from Idaho), Morocco (PR4: from Qued Zem), Russia (PR5 from Slyudanka), and Japan (PR6: from Okinawa) were selected and compared using X-ray fluorescence (XRF), inductively coupled plasma mass spectrometry (ICP-MS) and X-ray diffraction (XRD). Elemental analysis results of PR samples showed that they were mainly composed of Ca, P, Si, Al, S and Fe. Total phosphate concentration in all PRs was 6 to 38% on the average. The Cd concentration levels in all PR samples ranged from 0.15 to 507 mg kg − 1 . PR4 sample exhibited about two times higher Cd concentration than those of the literatures so far published. XRD analysis revealed that; fluorapatite ((Ca 5 (PO 4 ) 3 )F), hydroxyapatite (Ca 10 (PO 4 ) 6 (OH) 2 ) and carbonate fluorapatite (Ca 5 (PO 4 ,CO 3 ) 3 F) were the dominant minerals. This study also confirmed that PR3 and PR4 exhibited higher Cd content and prominent mineral component was carbonate fluorapatite, suggesting that Cd might be exchanged to Ca and/or occluded in carbonate fluorapatite during its formation by sedimentation.

Cadmium (Cd) is a common impurity in phosphate fertilizers and application of phosphate fertilizer may contribute to soil Cd accumulation. Changes in Cd burdens to agricultural soils and the potential for plant Cd accumulation resulting from fertilizer input were investigated in this study. A field experiment was conducted on Haplaquept to investigate the influence of calcium superphosphate on extractable and total soil Cd and on growth and Cd uptake of different Komatsuna (Brassica rapa L. var. perviridis) cultivars. Four cultivars of Komatsuna were grown on the soil and harvested after 60 days. The superphosphate application increased total soil Cd from 2.51 to 2.75 mg kg−1, 0.1 mol L−1 hydrochloric acid (HCl) extractable Cd from 1.48 to 1.55 mg kg−1, 0.01 mol L−1 HCl extractable Cd from 0.043 to 0.046 mg kg−1 and water extractable Cd from 0.0057 to 0.0077 mg kg−1. Cd input reached 5.68 g ha–1 at a rate of 240 kg ha–1 superphosphate fertilizer application. Superphosphate affected dry-matter yield of lea...

The phosphorylated sago starch-extraction residue (P-SR) was produced for the removal of heavy metal from wastewater. The phosphoric ester in the phosphorylated residue was evaluated by means of infrared microspectrometry and solid-state NMR. In this study, the phosphorus contents of produced P-SR, phosphorylated cellulose (P-C), and phosphorylated sago starch were 31.7, 34.2, and 4.6 mg/g, respectively. The phosphorus contents of P-C and sago starch were clearly different because of the difference of each structure. The maximum sorption capacities of heavy metals (cadmium, lead, copper, and zinc) in single heavy metal sorption on P-SR were 0.20, 0.25, 0.36, and 0.24 mmol/g (Cu > Pb > Zn > Cd), respectively. On the other hand, the amount of sorbed heavy metals in coexisted heavy metal sorption on P-SR followed the order of Pb > Cu > Cd > Zn that was different from the relations of maximum sorption capacities for individual heavy metals. The heavy metal sorption behavior in single and coexisted heavy metal solution for P-SR were different and P-SR showed the intrinsic heavy metal sorption affinity, called as selective sorption. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Amount of nitrogen (N) dry deposition on the leaf surface of oak and cedar was compared using throughfall method and foliar rinsing method. The study was conducted at FM Tamakyuryo, located at the northeast edge of the Tama Rolling Hills, Tokyo, Japan. The throughfall method showed that the total N deposition were 19.7, 19.1, and 50.6 kg N ha−1 year−1 for open bulk deposition and total deposition in oak forest and cedar forest, respectively. The deposition of ammonium nitrogen on leaf surface were 0.29 ± 0.38 (average ± standard deviation) and 0.75 ± 1.06 mg N m−2 for oak and cedar, respectively, and that of nitrate nitrogen were 0.15 ± 0.18 and 0.35 ± 0.28 mg N m−2, respectively. Dry deposition on leaf surface was influenced by the cumulative amount of rainfall before sampling and was found to be easily washed off with high amount of precipitation within a few days.

Previous trials have revealed variable responses of sago palm (Metroxylon sagu Rottb.) to fertilizer application, particularly nitrogen (N). In the present study, we quantified the fertilizer use efficiency (FUE) of sago palm for the first time using 15N-labeled fertilizer in pot and field experiments. The pot experiment was conducted in Japan using a 2:1 mixture of sand to Philippine soil. The field experiment was conducted in Leyte in the Philippines. Both experiments consisted of three replicates in each of three treatments: control, 15N urea at 50 kg N ha−1 and 15N urea at 100 kg N ha−1. The N uptake of sago palm increased significantly, but inconsistently with increasing N application. The few instances of a significant increase in N uptake did not translate into significant improvements in growth parameters, except for the number of leaflets in the pot experiment. The FUE values for sago seedlings (

The objective of this study is to assess the applicability of a commercial magnesium oxide (MgO) and a composite material containing MgO and natural minerals ('MgO-SH-A') as the soil amendments for suppression of cadmium (Cd) uptake and accumulation into rice grains. Firstly, the mineralogical and physicochemical properties, soil neutralizing capacities and Cd sorption characteristics of these materials were investigated. Both materials were strongly alkaline and possessed large surface areas. The X-ray diffraction pattern of MgO-SH-A indicated the presence of MgO and a magnesium-silicate mineral (antigorite) as the main components. MgO-SH-A showed a milder soil neutralizing capacity as compared to commercial MgO. The sorptions of Cd on commercial MgO and MgO-SH-A both fitted Langmuir isotherm. The maximum Cd sorption capacity of commercial MgO (46.8 mmol g(-1) DW) was higher than that of MgO-SH-A (5.87 mmol g(-1) DW), although the latter material showed higher affinity to Cd as compared to the former one. The dominant reaction involved in the Cd sorptions was suggested to be precipitation of Cd(OH)2 on the material surface. About 40% of Cd sorbed on MgO-SH-A was resistant to desorption by 0.1 M HCl, implying that this portion was strongly retained on the material surface.

The objective of this study is to assess the applicability of a commercial magnesium oxide (MgO) and a composite material containing MgO and natural minerals (‘MgO-SH-A’) as the soil amendments for suppression of cadmium (Cd) uptake and accumulation into rice grains. A cultivation experiment of rice plants ( Oryza sativa L. cv. Kinuhikari) was conducted in an actual Cd-contaminated alluvial paddy field to evaluate the effectiveness of these materials. The ‘plant available’ fractions of Cd in the paddy soil significantly decreased by application of commercial MgO at 2250 kg ha −1 or MgO-SH-A at 4500 kg ha −1 . These decreases would be primarily attributed to the increase in soil pH due to applications of the MgO materials because these soil Cd fractions were significantly negatively correlated with the soil pH. Even under a suppressive condition for Cd uptake by rice plants, i.e., continuous flooding of the paddy field around the heading stage, applications of these materials further reduced Cd concentration in brown rice as compared to that from the control. It was concluded that the two MgO materials examined would be effective in preventing Cd contamination of rice grains grown in Cd-polluted paddy fields.

This study investigated the continuous record of eutrophication in Lake Onuma based on the geochemical properties of two lake sediment cores obtained from the deepest part of the lake in 2011. Based on a tuff layer deposited during the eruption of Mt. Komagatake, and on the correlation between fluctuations in δ13C and δ15N values, two sediment cores, ON11-2-2 and ON11-6, were dated to the 1920s and 1890s, respectively. The δ13C value and C/N ratio for the lake sediments show values within the ranges for planktonic material and river sediment, suggesting that the lake sediment is a mixture of these sources and that their mixture ratio was almost constant since the 1920s. On the other hand, the δ15N of two cores show a similar trend with increasing δ15N from the 1950s–1960s to the present time. It is attributed to the increase in the δ15N value of planktonic material reflecting anthropogenic nitrogen inflow to the lake.

To analyze in greater detail the fate and behavior of toxic organotin compounds in the environment, total tin (Sn) concentrations were determined for sediments of the Arakawa River, the Sumida River, and Tokyo Bay by using a graphite furnace atomic absorption spectrophotometer (GFAAS). Sn concentrations in 2000 were compared with those of 1984 (8 years before the regulation on tributyltin-based antifouling paint) as well as with other heavy metals (Cu, Ni, Pb, and Zn). The Sn concentrations ranged from 1.04 to 4.43 mg kg−1 for sediments sampled in 2000. Although the average concentration of Sn in the sediments was low compared with that of 1984, the concentration tended to increase at several sites in 2000. Moreover, the Sn concentration showed significant correlations with the Cu, Ni, Pb, and Zn concentrations. These results suggest that a significant proportion of the overall Sn content in these sediments was probably introduced from the sources other than antifouling paint. The metals extracte...

Endophytic nitrogen-fixing organisms have been isolated from the aerial parts of field-grown sweet potato (Ipomoea batatas). The (15)N dilution method, which is based on the differences in stable nitrogen isotope ratios, is useful for measuring nitrogen fixation in the field. In this study, seedlings of two sweet potato cultivars, 'Beniazuma' and 'Benikomachi,' were transplanted into an alluvial soil that had been treated with organic improving material in advance. Whole plants were sampled every 2 or 3 weeks. After separating plants into tuberous roots and leaves, the fresh weights of the samples were measured, and the nitrogen content and natural (15)N content of leaves were determined with an elemental analyzer and an isotope ratio mass spectrometer linked to an elemental analyzer, respectively. The contribution of nitrogen fixation derived from atmospheric N2 in sweet potato was calculated by assuming that leaves at 2 weeks after transplanting were in a non-nitrogen-fixing state. The contribution ratios of nitrogen fixation by nitrogen-fixing endophytes in leaves of both sweet potato cultivars increased rapidly from 35 to 61 days after transplanting and then increased gradually to 55-57% at 90 days after transplanting. Over the course of the sweet potato growing season, the activity of nitrogen-fixing endophytes in leaves began to increase at about 47 days after transplanting, the weight of leaves increased rapidly, and then growth of tuberous roots began a few weeks later. Our findings indicate that nitrogen-fixing endophytes will be activated under inorganic nitrogen-free sweet potato cultivation, allowing for growth of the tuberous roots.

The effect of acidic deposition on the soil under red pine forest in Chunchon, Korea was investigated. Precipitation, stream water, and soil solution chemistry were monitored at the watershed from 1997 to 1998. Acidity of the open-bulk precipitation was often neutralized by large amounts of ammonia (NH3) that might have originated from livestock farming and fertilization. Estimated elemental budget at the watershed showed a positive correlation between loss of base cations and proton (H+) production due to nitrogen transformation in soil (ΔH+NT: ([NH4+]in-[NH4+]out)- ([NO3−]in-[NO3−]out)). When ΔH+NT increased, concentrations of nitrate in soil solutions also increased. Consequently, pH values of soil solutions decreased, although ion exchange with base cations contributed to buffer reaction. Since acid buffering capacity of the red pine forest soil was small, it was concluded that the input of ammonium nitrogen enhanced nitrification in soil thus causing soil acidification represented by loss of base cations from the watershed.

Continuous monitoring studies focused on nitrogen saturation were conducted at the Rolling Land Laboratory (RLL) of the forest experimental station located in the Tama Hill region in Central Japan. Based on the nitrate concentration in stream water, it was estimated that the forest ecosystems at RLL could be classified into Stage 2 of nitrogen saturation. The stream water pH decreased when the nitrate concentration increased. Proton production due to N transformation (= ([NH4 +]th-[NH4 +]out)-([N03 -]th-[N03 -]out) amounted to 1.24 kmolc ha-1 y-1 in 1991–1992, a value 1.5 times as high as the total atmospheric proton input. Sulfate adsorption buffered the impact of the acid load. Protons were mainly consumed by ion exchange with base cations and weathering processes. Both acidic deposition and N transformation accelerated base cation mobilization. Nevertheless, soil pH values at RLL did not decrease due to the abundance in base cations.

Copper adsorption and desorption under acid conditions by soil clay fractions separated from Vertisol, Planosol and Gleyic Acrisol has been studied in 0.01 M Ca(NO3)2. A Freundlich equation was appropriate to describe Cu adsorption. Within the range of 150 to 2600 mg of copper per kg of soil clay fraction the proportions of Cu not displaced during 5 successive 48-hour desorptions with 0.01 M Ca(NO3)2 decreased with increasing adsorption density and at the lower pHs. The proportions ranged from as high as 0.98 in the case of the Vertisol clay (pH 5.3) to as low as 0.12 (88% desorption) in the Planosol clay (pH 4.5). Measurement of separation factors (α Cu/Ca) showed that the preference of the clay surface for Cu over Ca decreased in the order: Gleyic Acrisol > Planosol > Vertisol. A considerable amount of sorbed copper could be solubilized by decreasing pH values to 4 when in the Planosol clay 39% was desorbed and 45% was desorbed in the Gleyic Acrisol clay.

The surface charges and the adsorption of copper (Cu) and zinc (Zn) on tropical peat soils which are poorly documented were investigated as a function of solution pH and Cu and Zn equilibrium concentrations. The point of zero charge of tropical peat soils from Malaysia and Thailand was lower than the original soil pHs. The adsorption of Cu and Zn remarkably increased with the increase of the solution pH and the equilibrium concentrations following the Langmuir adsorption isotherm equation. The adsorption of Cu on tropical peat soils was larger than that of Zn at the same pH value which was controlled with an automatic pH regulator. The relationship between the proton release and Cu and Zn adsorption was in the range of 1 to 2, suggesting that Cu and Zn replaced one or two protons from the sites with proton adsorption of tropical peat soils, although the proton consumption by hydrolytic Cu and Zn ions in the solution and dissociated carboxyl groups of tropical peat soils caused the decrease in the...

In order to understand the effects of oxidation on heavy metal behavior in sediments, the changes in chemical phase distributions of heavy metals with oxidation of sediments from Lake Teganuma were investigated using a sequential chemical extraction procedure for heavy metals. The exposure of sediments from the lake bottom to atmosphere caused the increase of Eh and the decrease of acid volatile-S in sediments. Most of the cadmium is expected to exist as relatively stable forms such as sulfides in original reduced sediments prior to exposure to the atmosphere. With the oxidation of sediments, Cd in the sulfidic/organic fraction were transformed to forms in the exchangeable and the reducible fractions which are easily dissolved. The chemical phase changes of Cu, Pb and Zn in sediments were less drastic than the case of Cd. Cadmium distinctly affected by the change in redox potential in sediments, and its behavior in the oxidized state is most mobile. Compared to Cd, the behavior of Cu and Pb are not so remarkably affected by the change in redox condition of sediments.

Heavy metal concentrations and other physical and chemical properties were studied so as to assess the heavy metal accumulation process in the sediments of a hypereutrophic lake, Lake Teganuma, Japan. The accumulations were most evident near the inflow inlets of two main inflow rivers in Kaminuma (the west part of Lake Teganuma) with the significant Zn accumulation. Except for Fe, the vertical distributions of heavy metals showed the highest concentrations in the surface 10 cm and decreased gradually with the sediment depth. The high concentrations in the upper layer was caused by an increase in the non-residual fractions. The large influx of heavy metal to Lake Teganuma seems to be due to the domestic effluents via the two rivers in last decades.

The residue produced by the extraction of sago starch is usually discarded as a waste material. In this study, we phosphorylated the sago starch-extraction residue with phosphoryl chloride and used the phosphorylated residue to remove cadmium from wastewater. The phosphoric ester functionality in the phosphorylated residue was evaluated by means of infrared microspectrometry and solid-state NMR. The dependence of the cadmium sorption behavior on pH, contact time, and electrolyte concentration and the maximum sorption capacity of the phosphorylated residue were also studied. The cadmium sorption varied with pH and electrolyte concentration, and the maximum sorption capacity was 25.2 mg g −1 , which is almost half the capacity of commercially available weakly acidic cation exchange resins. The phosphorylated residue could be reused several times, although cadmium sorption gradually decreased as the number of sorption–desorption cycles increased. The phosphorylated residue sorbed cadmium rapidly, which is expected to be favorable for the continuous operation in a column.

The adsorption of cations and anions on synthetic amorphous aluminosilicates was investigated in the 0.1 M NaNO3 system. The amorphous aluminosilicates were synthesized by mixing 0.1 m A1C13 and 0.1 M Na2SiO3 at pH 3.1, and mixing 0.1 M NaAl(OH)4 and 0.1 m Na2SiO3 at pH 12.5, and by allowing the mixture to stand for 2 h at pH 6 with the addition of alkali and acid solutions, respectively. The adsorption of ions on the synthetic aluminosilicates was in the order of Cu(II)>Zu(II)>Mg(II), and P(V)>Se(VI)>Cr(VI) and it was controlled by the bulk pH, SiO2/Al2O3 molar ratio and coordination number of aluminum in the aluminosilicates. Aluminosilicates with 6-fold coordinated aluminum adsorbed a smaller amount of cations and a larger amount of oxyanions than those with 4-fold coordinated aluminum. The aluminum coordination number appears to major role in the adsorption of various ions in soils.

The adsorption of oxyanions, P(V), As(V), Se(IV), Mo(VI), and Cr(VI), on the synthetic hydrated oxides of iron and aluminum was studied. The adsorption sequence of the oxyanions was in the order of As(V), Se(IV)>Mo(VI)>P(V)>Cr(VI) on the goethites, hydrons ferric oxide and hydrous aluminum oxide, and P(V)>Mo(Vl)> As(V)>Se(IV), Cr(VI) on the gibbsites. The amount of adsorption of the oxyanions on the hydrated oxides of iron and aluminum was larger in the amorphous hydrous oxides than in the crystalline ones. Ligand exchange took place between oxyanions and OH or OH2 coordinated on the hydrated oxides of iron and aluminum during the adsorption. The OH2 ligand exchange mainly occurred at pH 5.5 for the adsorption of As(V), Se(IV), and P(V) on the amorphous hydrated oxides of iron and aluminum.