STUDY ON THE OXIDIZABILITY-RESISTANCE OF FLEXIBLE GRAPHITE BY USING ADDITIVE

The oxidizability-resistance of graphite products have been studied with the addition of H3PO4 and H3BO3. A available way has been found to increase the oxidizability-resistance of graphite products. The oxidizability-resistance of graphite products rises remarkably after treating with 1% H3PO4 and 3% H3BO3. Meanwhile, the relative princi-ple has been proposed also.

Effects of land-use types on the vertical distribution of fractions of oxidizable organic carbon on the Loess Plateau, China

The oxidizability of soil organic carbon （SOC） influences soil quality and carbon sequestration. Four fractions of oxidizable organic carbon （very labile （C1）, labile （C2）, less labile （C3） and non-labile （C4）） reflect the status and composition of SOC and have implications for the change and retention of SOC. Studies of the fractions of oxidizable organic carbon （OC） have been limited to shallow soil depths and agroecosystems. How these fractions respond at deep soil depths and in other types of land-use is not clear. In this study, we evaluated the vertical distributions of the fractions of oxidizable organic carbon to a soil depth of 5.0 m in 10 land-use types in the Zhifanggou Watershed on the Loess Plateau, China. Along the soil profile, C1 contents were highly variable in the natural grassland and shrubland I （Caragana microphylla）, C2 and C4 contents were highly variable in the natural grassland and two terraced croplands, respectively, and C3 contents varied little. Among the land-use types, natural grassland had the highest C1 and C2 contents in the 0-0.4 m layers, followed by shrubland I in the 0-0.1 m layer. Natural grassland had the highest C4 contents in the 1.0-4.5 m layers. Natural grassland and shrubland I thus contributed to improve the oxidizability of SOC in shallow soil, and the deep soil of natural grassland has a large potential to sequester SOC on the Loess Plateau.

Effects of long-term fertilization on oxidizable organic carbon fractions on the Loess Plateau,China

The effects of long-term fertilization on pools of soil organic carbon （SOC） have been well studied, but limited information is available on the oxidizable organic carbon （OOC） fractions, especially for the Loess Plateau in China. We evaluated the effects of a 15-year fertilization on the OOC fractions （F1, F2, F3 and F4） in the 0-20 and 20-40 cm soil layers in flat farmland under nine treatments （N （nitrogen, urea）, P （phosphorus, monocalcium phosphate）, M （organic fertilizer, composted sheep manure）, N＋P （NP）, M＋N （MN）, M＋P （MP）, M＋N＋P （MNP）, CK （control, no fertilizer） and bare land （BL, no crops or fertilizer））. SOC content increased more markedly in the treatment containing manure than in those with inorganic fertilizers alone. F1, F2, F4 and F3 accounted for 47%, 27%, 18% and 8% of total organic carbon, respectively. F1 was a more sensitive index than the other C fractions in the sensitivity index （SI） analysis. F1 and F2 were highly correlated with total nitrogen （TN） and available nitrogen （AN）, F3 was negatively correlated with pH and F4 was correlated with TN. A cluster analysis showed that the treatments containing manure formed one group, and the other treatments formed another group, which indicated the different effects of fertilization on soil properties. Long-term fertilization with inorganic fertilizer increased the F4 fraction while manure fertilizer not only increased labile fractions （F1） in a short time, but also increased passive fraction （F4） over a longer term. The mixed fertilizer mainly affected F3 fraction. The study demonstrated that manure fertilizer was recommended to use in the farmland on the Loess Plateau for the long-term sustainability of agriculture.

Active organic carbon pool of coniferous and broad-leaved forest soils in the mountainous areas of Beijing

In order to explore the effects of different forest types on active soil carbon pool, the amounts and density of soil organic carbon （SOC） were studied at different soil horizons under typical coniferous and broad-leaved forests in the mountainous area of Beijing. The results showed that the amount of total SOC, readily oxidizable carbon and particulate organic carbon decreased with increasing depths of soil horizons and the amounts at depths of 0-10 cm and 10-20 cm in broad-leaved forest was clearly higher than that in coniferous forests. The trend of a decrease in SOC density with increasing depth of the soil horizon was similar to that of the amount of SOC. However, no regular trend was found for SOC density at different depths between coniferous forest and broad-leaved forests. The ratio of readily oxidizable carbon to total amount of SOC ranged from 0.36-0.45 and the ratio of particulate organic carbon to total amount of SOC from 0.28-0.73; the ratios decreased with increasing depths of soil horizons. Active SOC was significantly correlated with total SOC; the relationship between readily oxidizable carbon and particulate organic carbon was significant. A broad-leaved forest may produce more SOC than a coniferous forest.

Soil carbon pools of six ecological regions of the United States

Mineralisable soil organic carbon(SOC)pools vary with ecosystem type in response to changes in climate,vegetation and soil properties.Understanding the effect of climate and soil factors on SOC pools is critical for predicting change over time.Surface soil samples from six ecoregions of the United States were analyzed for permanganate oxidizable C(KMnO4-C)and mineralizable C pools.Variations of SOC ranged from 7.9 mg g^-1(Florida site)to 325 mg g^-1(Hawaii site).Mineralisable C pools and KMnO4-C were highest in soils from the Hawaii site.Mean annual precipitation explains SOC and resistant C pool variations.Clay content was related to mineralisable active C pools and bacterial abundance.Mean annual precipitation and clay content are potential variables for predicting changes in SOC pools at large spatial scales.

Relationship among Different Soil Biochemical Methods to Determine Soil Health

Numerous soil biochemical methods are used to determine the soil health status, but the relationships among these methods are not well understood. Relationships among soil biochemical tests, 1) chloroform fumigated microbial biomass C (CFMBC), 2) permanganate oxidizable C (POXC), 3) Solvita CO2-burst (Solvita), 4) Solvita labile amino nitrogen (SLAN), and short-term soil CO2 efflux during laboratory incubation using (v) Alkali-base trap (Alkali) and (vi) infrared gas analyzer (IRGA), were evaluated for nine agricultural soils collected across the Red River Valley of North Dakota and Minnesota, USA. Not a single test is comprehensive to relate with all soil biochemical tests. Coefficient of variation percentage for particular method varied with soil type. Among six tests, CFMBC is significantly (p < 0.05) related with Alkali (r = 0.37), Solvita (r = 0.57), SLAN (r = 0.52), and POXC (r = 0.68). Soil CFMBC correlates with most of soil biochemical tests and can be potential to determine soil biochemical condition.

Insight into the adsorption behavior and mechanism of trace impurities from H_(2)O_(2) solution on functionalized zirconia by tuning the structure of amino groups

Primary,secondary and tertiary amino-functionalized zirconia(ZrO_(2)-NH_(2),ZrO_(2)-NH and ZrO_(2)-N)was synthesized by the postgrafting method for the adsorption removal of typical metallic ions,phosphate and total oxidizable carbon from a real H_(2)O_(2) solution.ZrO_(2)-NH_(2),ZrO_(2)-NH and ZrO_(2)-N exhibited similar pore sizes and sequentially increased zeta potentials.The adsorption results of single and binary simulated solutions showed that the removal efficiency increased in the order of Fe^(3+)>Al^(3+)>Ca^(2+)>Na^(+).There is competitive adsorption between metallic ions,and Fe^(3+) has an advantage over the other metals,with a removal efficiency of 90.7%.The coexisting phosphate could promote the adsorption of metallic ions,while total oxidizable carbon had no effect on adsorption.The adsorption results of the real H_(2)O_(2)solution showed that ZrO_(2)-NH_(2) exhibited the best adsorption affinity for metallic ions,as did phosphate and total oxidizable carbon,with a total adsorption capacity of 120.9 mg·g_(-1).Density functional theory calculations revealed that the adsorption process of metallic ions involves electron transfer from N atoms to metals and the formation of N-metal bonds.

Simultaneous removal of total oxidizable carbon,phosphate and various metallic ions from H_(2)O_(2) solution with amino-functionalized zirconia as adsorbents

Amino-functionalized zirconia was synthesized by the co-condensation method using zirconium butanol and 3-aminopropyltriethoxy silane for the simultaneous removal of various impurities from aqueous 30% H_(2)O_(2) solution.The results of Fourier transform infrared(FTIR)and Zeta potential showed that the content of N in amino-functionalized zirconia increased with the added amount of 3-aminopropyltriethoxy silane.Accordingly,the removal efficiency of total oxidizable carbon,phosphate and metallic ions from the H_(2)O_(2) solution increased.The adsorbent with an N content of 1.62%exhibited superior adsorption performance.The removal efficiency of 82.7% for total oxidizable carbon,34.2%for phosphate,87.1% for Fe^(3+),83.2%for Al^(3+),55.1%for Ca^(2+)and 66.6%for Mg^(2+),with a total adsorption capacity of 119.6 mg·g^(-1),could be achieved.The studies conducted using simulated solutions showed that the adsorption process of phosphate on amino-functionalized zirconia is endothermic and spontaneous,and the behaviors could be well described by the pseudo-second-order model and Langmuir model with a maximum adsorption capacity of 186.7 mg·g^(-1).The characterizations of the spent adsorbents by Zeta potential,FTIR and X-ray photoelectron spectroscopy revealed that the adsorption mechanism of phosphate is predominantly electrostatic attraction by the protonated functional groups and complementary ligand exchange with zirconium hydroxyl groups.

Sensitivity of Labile Soil Organic Carbon Pools to Long-Term Fertilizer, Straw and Manure Management in Rice-Wheat System

Labile soil organic carbon （SOC） pools, estimated through chemical fractionation techniques, are considered sensitive indicators of management-induced changes in quality and composition of soil organic matter. Although the impacts of organic manure and crop residue applications on C sequestration in rice-wheat system are fairly well documented, their influence on labile SOC pools is relatively less known. Impacts of organic manure, rice straw, and inorganic fertilizer nitrogen （N） applications on soil total organic carbon （TOC） and SOC pools including water-extractable organic C （WEOC）, hot water-soluble organic C （HWOC）, potassium permanganate- oxidizable organic C （KMnO4-C）, microbial biomass C （MBC）, mineralizable organic C （Cmin）, and the oxidizable fractions of decreasing oxidizability （easily-oxidizable, oxidizable, and weakly-oxidizable） were investigated in an ll-year field experiment under rice-wheat system. The field experiment included treatments of different combinations of farmyard manure, rice straw, and fertilizer N application rates, with C inputs estimated to be in the range from 23 to 127 Mg ha-1. After 11 years of experiment, WEOC, HWOC, and KMnO4-C were 0.32%-0.50%, 2.2%-3.3%, and 15.0%-20.6% of TOC, respectively. The easily-oxidizable, oxidizable, and weakly-oxidizable fractions were 43%-57%0, 22%-27%, and 10%-19% of TOC, respectively. The applications of farmyard manure and rice straw improved WEOC, HWOC, KMnO4-C, easily-oxidizable fraction, Cmin, and MBC, though the rates of change varied considerably from -14% to 145% and -1170 to 83% of TOC, respectively. At the C input levels between 29 and 78 Mg C ha-1 during the ll-year period, the greatest increase was observed in WEOC and the minimum in KMnO4-C. Water-extractable organic C exhibited a relatively greater sensitivity to management than TOC, suggesting that it may be used as a sensitive indicator of management-induced changes in soil organic matter under rice-wheat system. All the other labile SOC pools exhibited almost the same sensitivity to management as TOC. Most of the SOC pools investigated were positively correlated to each other though their amounts differed considerably. Long-term applications of farmyard manure and rice straw resulted in build-up of not only the labile but also the recalcitrant pool of SOC, emphasizing the need for continued application of organic amendments for permanence of the accrued C under the experimental conditions.

Responses of Soil Microbial Community Structure and Activity to Incorporation of Straws and Straw Biochars and Their Effects on Soil Respiration and Soil Organic Carbon Turnover

Like straw, biochar incorporation can influence soil microorganisms and enzyme activities and soil carbon(C) responses;however,few studies have compared the various effects of straw and biochar and the underlying mechanisms. An experiment was performed to study the changes in soil respiration(SR) and soil organic C(SOC) fluxes in response to the incorporation of three kinds of straw(reed, smooth cordgrass, and rice) and their pyrolyzed products(biochars) at Chongming Island, China. In addition, the microbial activity and community structure of some amended soils were also analyzed to clarify the mechanisms of these responses. The results showed that all biochar incorporation(BC) induced lower SR than the corresponding unpyrolyzed straw incorporation(ST), and the average SR in the soils following BC and ST during the experimental periods was 21.69 and 65.32 μmol CO2 m^-2s^-1, respectively.Furthermore, the average SOC content was 16.97 g kg-1 following BC, which was higher than that(13.71 g kg-1) following ST,indicating that compared to ST, BC was a low-C strategy, even after accounting for the C loss during biochar production. Among the BC treatments, reed-BC induced the lowest SR(17.04 μmol CO2 m^-2s^-1), whereas smooth cordgrass-BC induced the highest SR(27.02 μmol CO2 m^-2s^-1). Furthermore, in contrast with ST, BC significantly increased the abundance of some bacteria with poorer mineralization or better humification ability, which led to lower SR. The lower easily oxidizable C(EOC) and higher total C contents of biochars induced lower SR and higher SOC in the soil following BC compared to that following ST. Among the BC treatments,the higher total nitrogen content of rice biochar led to significantly higher soil microbial biomass, and the lower EOC content of reed biochar led to lower soil microbial activity and SR.

Application of Ordinary Kriging in Mapping Soil Organic Carbon in Zambia

The quantification of the pattern and spatial distribution of soil organic carbon （SOC） is fundamental to understand many ecosystem processes. This study aimed to apply ordinary kriging （OK） to model the spatial distribution of SOC in a selected part of Zambia. A total of 100 soil samples were collected from the study area and analyzed for SOC by determining soil oxidizable carbon using the Walkley-Black method. An automated fitting procedure was followed when modeling the spatial structure of the SOC data with the exponential semivariogram. The results indicated that the short range spatial dependence of SOC was strong with a nugget close to zero. The spatial autocorrelation was high to medium with a nugget to sill ratio of 0.25. The root mean square error of the predictions was 0.64, which represented 58.18% of the mean observed data for SOC. It can be concluded that the generated map could serve as a proxy for SOC in the region where evidence of spatial structure and quantitative estimates of uncertainty are reported. Therefore, the maps produced can be used as guides for various uses including optimization of soil sarapling.

Screening of textile finishing agents available on the Chinese market: An important source of per-and polyfluoroalkyl substances to the environmentpolyfluoroalkyl substances to the environment

Organofluorinated surfactants are widely employed in textile finishing agents (TFAs) to achieve oil, water, and stain repellency. This has been regarded as an important emission source of per-and polyfluoroalkyl substances (PFASs) to the environment. China is the biggest manufacturer of clothes, and thus TFA production is also a relevant industrial activity. Nevertheless, to date, no survey has been conducted on PFAS contents in commercially available TFAs. In the present study, TFA products were investigated by the Kendrick mass defect method. The quantification results demonstrated a significant presence of perfluorooctane sulfonate (0.37 mg/L) in TFAs manufactured by electrochemical fluorination technology. The products obtained by short-chain PFAS-based telomerization were dominated by perfluorooctanoic acid (mean concentration: 0.29 mg/L), whose values exceeded the limits stated in the European Chemical Agency guidelines (0.025 mg/L). Moreover, the total oxidizable precursor assay indicated high levels of indirectly quantified precursors with long alkyl chains (C7–C9). Together, these results suggest that there is currently a certain of environmental and health risks in China that originates from the utilization of TFAs, and a better manufacturing processes are required to reduce such risks.

Reduced tillage with residue retention improves soil labile carbon pools and carbon lability and management indices in a seven-year trial with wheat-mung bean-rice rotation

Soil total organic carbon(TOC)is a composite indicator of soil quality with implications for crop production and the regulation of soil ecosystem services.Research reports on the dynamics of TOC as a consequence of soil management practices in subtropical climatic conditions,where microbial carbon(C)loss is high,are very limited.The objective of our study was to evaluate the impact of seven years of continuous tillage and residue management on soil TOC dynamics(quantitative and qualitative)with respect to lability and stratification under an annual wheat-mung bean-rice cropping sequence.Composite soil samples were collected at 0-15 and 15-30 cm depths from a three-replicate split-plot experiment with tillage treatment as the main plots and crop residue levels as the sub-plots.The tillage treatments included conventional tillage(CT)and strip tillage(ST).Residue levels were high residue level(HR),30%of the plant height,and low residue level(LR),15%.In addition to TOC,soil samples were analyzed for particulate organic C(POC),permanganate oxidizable C(POXC),basal respiration(BR),specific maintenance respiration rate(qCO_(2)),microbial biomass C(MBC),potentially mineralizable C(PMC),and TOC lability and management indices.The ST treatment significantly increased the TOC and labile C pools at both depths compared with the CT treatment,with the effect being more pronounced in the surface layer.The HR treatment increased TOC and labile C pools compared with the LR treatment.The ST+HR treatment showed significant increases in MBC,metabolic quotient(qR),C pool index(CPI),C lability index(CL_(I)),and C management index(CMI),indicating improved and efficient soil biological activities in such systems compared with the CT treatment.Similarly,the stratification values,a measure of soil quality improvement,for POC and MBC were>2,indicating improved soil quality in the ST+HR treatment compared with the CT treatment.The ST+HR treatment not only significantly increased the contents of TOC pools,but also their stocks.The CMI was correlated with qCO_(2),BR,and MBC,suggesting that these are sensitive indicators of early changes in TOC.The qCO_(2) was significantly higher in the CT+LR treatment and negatively correlated with MBC and CMI,indicating a biologically stressed soil condition in this treatment.Our findings highlight that medium-term reduced tillage with HR management has profound consequences on soil TOC quality and dynamics as mediated by alterations in labile C pools.

Cu/Co mixed hierarchical tubular heterostructures for alkaline supercapacitors

The hierarchical hollow structures of electrode materials s of supercapacitors is effective for the large specific surface area and fast ions and charge transports.Cu nanowires as self-engaged templates provide sites and paths for the nucleation and growth of the ZIF-67.Meanwhile,Cu atoms can disperse into metal organic frameworks(MOFs)to form Cu-Co mixed oxides and construct heterostructures.In this case,Cu nanowires are used as a template and an activated part to improve the internal electronic structures.The electrochemical performance can be improved due to these features.Herein,Cu nanowires and MOFs are combined via a mild and efficient approach to fabricate Cu-Co-O/CuO electrode materials.This electrode exhibits excellent electrochemical performance with a specific capacitance of 834.1 F g^(-1) at 1 A g^(-1).The assembled asymmetric supercapacitor(ASC)shows an ultra-high energy density of 40.7 W h kg^(-1) at a power density of 915 W kg^(-1) and a good capacitance retention after 8000 cycles in a 2 M KOH aqueous solution.The results otained in this work indicate a strategy of the combination of reactive metals with metal organic frameworks used as electrode materials for electrochemical supercapacitors.