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Dissolved oxygen (DO) left in the voids of buffer and backfill materials of a deep geological high level radioactive waste (HLW) repository could cause canister corrosion. Available data from laboratory and in situ experiments indicate that microbes play a substantial role in controlling redox conditions near a HLW repository. This paper presents the application of a coupled hydro-bio-geochemical model to evaluate geochemical and microbial consumption of DO in bentonite porewater after backfilling of a HLW repository designed according to the Swedish reference concept. In addition to geochemical reactions, the model accounts for dissolved organic carbon (DOC) respiration and methane oxidation. Parameters for microbial processes were derived from calibration of the REX in situ experiment carried out at the Äspö underground laboratory. The role of geochemical and microbial processes in consuming DO is evaluated for several scenarios. Numerical results show that both geochemical and microbial processes are relevant for DO consumption. However, the time needed to consume the DO trapped in the bentonite buffer decreases dramatically from several hundreds of years when only geochemical processes are considered to a few weeks when both geochemical reactions and microbially-mediated DOC respiration and methane oxidation are taken into account simultaneously. [Copyright &y& Elsevier]

Domestic wastewater is a significant source of nitrogen and phosphorus, which cause lake eutrophication. Among the wastewater treatment technologies, constructed wetlands are a promising low-cost means of treating point and diffuse sources of domestic wastewater in rural areas. However, the sustainable operation of constructed wetland treatment systems depends upon a high rate conversion of organic and nitrogenous loading into their metabolic gaseous end products, such as N2O and CH4. In this study, we examined and compared the performance of three typical types of constructed wetlands: Free Water Surface (FWS), Subsurface Flow (SF) and Vertical Flow (VF) wetlands. Pollutant removal efficiency and N2O and CH4 emissions were assessed as measures of performance. We found that the pollutant removal rates and gas emissions measured in the wetlands exhibited clear seasonal changes, and these changes were closely associated with plant growth. VF wetlands exhibited stable removal of organic pollutants and NH3-N throughout the experiment regardless of season and showed great potential for CH4 adsorption. SF wetlands showed preferable T-N removal performance and a lower risk of greenhouse gas emissions than FWS wetlands. Soil oxidation reduction potential (ORP) analysis revealed that water flow structure and plant growth influenced constructed wetland oxygen transfer, and these variations resulted in seasonal changes of ORP distribution inside wetlands that were accompanied by fluctuations in pollutant removal and greenhouse gas emissions. [ABSTRACT FROM AUTHOR]

Most of the standardized biodegradation tests used to assess the ultimate biodegradation of environmentally degradable polymers are based solely on the determination of net evolved carbon dioxide. However, under aerobic conditions, it has to be considered that heterotrophic microbial consortia metabolize carbon substrates both to carbon dioxide and in the production of new cell biomass. It is generally accepted that in the relatively short term, 50% of the carbon content of most organic substrates is converted to CO2, with the remaining carbon being assimilated as biomass or incorporated into humus. The latter is particularly important when the metabolism of the organic matter occurs in a soil environment. A straightforward relationship between the free-energy content of a carbon substrate (expressed as the standard free-energy of combustion) and its propensity for conversion to new microbial biomass rather than mineralization to CO2 has been established. This can potentially lead to underestimation of biodegradation levels of test compounds, especially when they consist of carbon in a fairly low formal oxidation state and relatively high free-energy content. In the present work, the metabolism of different kind of carbon substrates, especially in soil, is reviewed and compared with our own experimental results from respirometric tests. The results show that conversion of highly oxidized materials, such as the commonly used reference materials, cellulose or starch, to CO2 may be significantly overestimated. The addition of glucosidic material to soil leads to greatly increased respiration and is accompanied by a very low conversion to biomass or humic substances. In contrast, relatively less oxidized substrates metabolize more slowly to give both CO2 and biomass to an extent which may be significantly underestimated if glucosidic materials are used as the reference. The need for an overall carbon balance taking into account both the carbon immobilized as biomass and that volatized as CO2 must be considered in standard respirometric procedures for assessing the biodegradability of slowly degrading macromolecules. [ABSTRACT FROM AUTHOR]

Methane (CH4) oxidation in soils is the only known biological sink of CH4. The sink strength of agricultural soils is known to be affected by soil properties and agricultural practices. We studied fluxes of CH4 in southern and northern Finland in arable soils with different texture and crops. The annual fluxes ranged from uptake of −1.2kgCH4 ha−1 to emission of 40kgCH4 ha−1. The CH4 oxidation decreased in the order loamy sand>well drained peat>clay>poorly drained peat. The more there were macropores or the less there were micropores in the soil, the higher was the mean annual CH4 oxidation rate. Calculated on the basis of the soil type specific CH4 flux rates from our study and the soil type distribution of Finnish agricultural soils, the total agricultural area in Finland would form an annual CH4 sink of −19Gg CO2 equiv., which is 0.3% of the total reported greenhouse gas emissions from agriculture in 2004. [Copyright &y& Elsevier]

We isolated four new ammonia-oxidizing bacterial strains from leucaena ( Leucaena leucocephala) grown in fields of an acid sulfate soil (ASS) in Thailand; 17SS from the surface soil and 17RS from the rhizoplane of a non-limed plot; 9SS from the surface soil and 9RS from the rhizoplane in a limed plot. The cells of all strains had the typical lobate shape of the genus Nitrosospira (“ Nitrosolobus”). The percentage similarity of the 16S rRNA genes of these strains to that of Nitrosospira (“ Nitrosolobus”) multiformis ATCC25196T (ATCC25196T) was 99.52% (strains 17SS, 17RS and 9SS) and 99.66% (strain 9RS). These newly isolated bacteria were all identified as Nitrosospira sp. Each strain, especially 17SS isolated from ASS, had higher urease activity than that of ATCC25196T. The o-acetylserine(thiol)lyase activity of 17SS was the highest of all the isolates. At pH 6.0, every isolate and ATCC25196T were able to utilize urea as the sole nitrogen source, in particular, strain 17SS grew best. The isolates from ASS showed higher urea utility than the isolates from the rhizoplane. Strain 17SS tolerated copper at levels up to 6.3 mmol L−1, but ATCC25196 T was inhibited at that concentration. [ABSTRACT FROM AUTHOR]

This study discusses the oxidation and dissolution rate of calcium sulphite in soils under variable pH and application conditions. Calcium sulphite hemihydrate is a byproduct of coal fired utility plants and is derived from flue gas desulfurization. Oxidation rates were found to decrease with increasing rates of application. The acidity of the soil should be adjusted to a pH of 6. 0 or greater. There appears to be ample time for oxidation/dissolution reactions to occur without introducing biocidal effects related to oxygen scavenging in no till systems with autumn surface applications of calcium sulphite in advance of spring plantings.

The distribution coefficient (Kd) expresses the relationship between the concentration of an element, which is adsorbed in the solid surface and its remaining concentration in the solution. The Kd is a very important factor in reactive transport, representing the source/sink term, and explaining the difference between the velocity of transport of non-conservative elements (Kd>0) and water flow velocity. In this paper, the Kd value for Zn element in loess like sediments forming the Pampeano aquifer is determined and this value is used in the modeling of reactive transport from the landfill of the city of Mar del Plata (Argentina). The determination of Kd value was done by means of batch experiments. The results obtained showed good agreement with Freundlich isotherm, with a value of KF=300.95 ml g−1 and a super index value b of 0.3961. These values were applied to reactive transport modeling using Visual Modflow code. The Zn plume obtained showed the low mobility of the element in the oxidizing conditions of the environment. [ABSTRACT FROM AUTHOR]

Sorption of the estrogens estrone (E1), 17β-estradiol (E2) and 17α-ethynylestradiol (EE2) on four soils was examined using batch equilibrium experiments with initial estrogen concentrations ranging from 10 to 1000 ng mL -1 . At all concentrations, >85% of the three estrogens sorbed rapidly to a sandy soil. E1 sorbed more strongly to soil than E2 or EE2. Partial oxidation of E2 to E1 was observed in the presence of soils. Autoclaving was more effective at reducing this conversion than inhibition with sodium azide or mercuric chloride, and had little effect on sorption, relative to the chemical microbial inhibitors. Sorption of EE2 was greater for fine-textured than coarse-textured soils, but greater than 90% of EE2 sorbed onto all four soils. The greatest degree of desorption of estrogens from the sandy soil occurred with the lowest initial concentration of 10 ng mL -1 and reached levels ≥80% for E1 and E2. Desorption of EE2 was greater in coarser textured soils than finer-textured soils. Again, relative desorption from all soils was greatest with low initial concentrations. Therefore, at environmentally relevant concentrations, estrogens quickly sorb to soils, and soils have a large capacity to bind estrogens, but these endocrine-disrupting compounds can become easily desorbed and released into the aqueous phase. [ABSTRACT FROM AUTHOR]

Methane (CH 4 ) and nitrous oxide (N 2 O) emissions from an irrigated rice field under continuous flooding and intermittent irrigation water management practices in northern China were measured in situ by the static chamber technique during May to October in 2000. The intermittent irrigation reduced total growing‐season CH 4 emission by 24.22% but increased N 2 O emission by 23.72%, when compared with the continuous flooding. Soil Eh and four related bacterial groups were also measured to clarify their effects on gaseous emissions. Three ranges of soil redox potential were related to gas emissions: below -100 mV with vigorous CH 4 emission, above +100 mV with significant N 2 O emission, and +100 to -100 mV with little CH 4 and N 2 O emissions. Intermittently draining the field increased soil oxidation, with a decrease in CH 4 emission and an increase in N 2 O emission. In general the mid‐season drainage slightly increased the populations of methanotrophs, nitrifiers, and denitrifiers but decreased that of methanogens. [ABSTRACT FROM AUTHOR]

No abstract available. [ABSTRACT FROM AUTHOR]

Potential reduction of methane emission from landfills employing its microbiological oxidation in soil materials depends on many factors. Very important is the methane concentration in the emitted gas and the availability of oxygen for methanotrophs. This paper reports predictions of methanotrophic activities (V) carried out on the basis of the Michaelis-Menten equation for the substrates CH4 and O2. The kinetic parameters used for the calculations were determined experimentally. The zone of the highest actual methanotrophic activity was situated at the surface of the column. The maximum value noted in this layer was 0.56 cm−3 kg d.w.−1h−1. [ABSTRACT FROM AUTHOR]

Both the advanced oxidation process (AOP) using a combination of hydrogen peroxide addition and microwave heating (H 2 O 2 /microwave), and the microwave heating process were used for solubilization of phosphorus from liquid dairy manure. About 80% of total phosphate was released into the solution at a microwave heating time of 5 min at 170°C. With an addition of H 2 O 2 , more than 81% of total phosphate could be released over a reaction period of 49 h at ambient temperature. The AOP process could achieve up to 85% of total phosphate release at 120°C. The results indicated that both the microwave, and the AOP processes could effectively release phosphate from liquid dairy manure. These processes could serve as pretreatments for phosphorus recovery from animal wastes, and could be combined with the struvite crystallization process to provide a new approach in treating animal wastes. [ABSTRACT FROM AUTHOR]

Abstract: The oxidation state of chromium in contaminated soils is an important indicator of toxicity and potential mobility. Chromium in the hexavalent state is highly toxic and soluble, whereas the trivalent state is much less toxic and relatively insoluble. A laboratory study investigated the impact of growing plants and supplemental organic matter on chromium transport in soil. Plants alone had no appreciable effect on the chromium oxidation state in soil. Soil columns with higher organic content were associated with lower ratios of chromate:total chromium than the columns with lower organic matter. Analyses of column leachate, plant biomass, and soil indicate that more chromium leaching occurred in the vegetated, low organic columns. Retention of Cr in the soils was correlated to the Cr(III) content. Plant uptake of chromium accounted for less than 1% of the chromium removed from the soil. Overall, the addition of organic matter had the strongest influence on chromium mobility. [Copyright &y& Elsevier]

Tree island ecosystems are important and distinct features of Florida Everglades wetlands. We described the inter-relationships among abiotic factors describing seasonally flooded tree islands and characterized plant–soil relationships in tree islands occurring in a relatively unimpacted area of the Everglades. We used Principal Components Analysis (PCA) to reduce our multi-factor dataset, quantified forest structure and vegetation nutrient dynamics, and related these vegetation parameters to PCA summary variables using linear regression analyses. We found that, of the 21 abiotic parameters used to characterize the ecosystem structure of seasonally flooded tree islands, 13 parameters were significantly correlated with four principal components, and they described 78% of the variance among the study islands. Most variation was described by factors related to soil oxidation and hydrology, exemplifying the sensitivity of tree island structure to hydrologic conditions. PCA summary variables describing tree island structure were related to variability in Chrysobalanus icaco (L.) canopy cover, Ilex cassine (L.) and Salix caroliniana (Michx.) canopy cover, Myrica cerifera (L.) plot frequency, litter turnover, % phosphorus resorption of co-dominant species, and nitrogen nutrient-use efficiency. This study supported findings that vegetation characteristics can be sensitive indicators of variability in tree island ecosystem structure. This study produced valuable, information which was used to recommend ecological targets (i.e. restoration performance measures) for seasonally flooded tree islands in more impacted regions of the Everglades landscape. [ABSTRACT FROM AUTHOR]

A novel 2-phenylethanol dehydrogenase has been purified from a soil bacterium Brevibacterium sp. KU 1309. The enzyme was purified about 1400-fold to homogeneity, and found to be a monomeric enzyme of apparent 39 kDa. The enzyme had broad substrate specificity and catalyzes a reversible oxidation of various primary alcohols to aldehydes. The enzyme required NAD+, but not NADP+ as a cofactor. Thus, the enzyme was classified into a group of NAD+-dependent primary alcohol dehydrogenase. The activity was inhibited by Cu2+, Ni2+, Ba2+, Hg2+ and p-chloromercuribenzoate. The enzyme is expected to be applicable as an effective biocatalyst in the oxidation of various alcohols. [Copyright &y& Elsevier]

Many wetland plants are faced with severe edaphic problems. Long term flooding effects a sequence of chemical processes that result in soil anoxia and production of several phytotoxic compounds. In order to maintain an aerobic root respiration wetland plants produce aerenchyms that enable oxygen conduction through the plant body to underground organs. Moreover wetland plants are able to release oxygen into the soil. This aeration effect of wetland plants in turn can influence soil chemistry considerably and protects roots by an aerobic rhizosphere. Oxygen release by underground organs of aerenchymous plants has been well documented in laboratory investigations but not under field conditions. In this study, dynamics of oxygen saturation were measured together with soil water content and microclimatic parameters. Measurements were carried out on some lowland peat covered byCarex rostrataStokes from July to October 2001. Oxygen saturation was quantified using novel optical sensors (microoptrodes). The presence ofC. rostratasignificantly increased oxygen content in the soil. Mean oxygen saturation underCarex rostrata(56.0%) was significantly higher than in a control plot without vegetation (26.6%). Due to fluctuating water content, oxygen saturation in both plots was characterized by pronounced time variation. Increasing soil water content caused an extreme decline of oxygen saturation in both plots and led to anoxia in the control plot. In the presence ofC.rostrata, the decline in soil oxygen took place at significantly higher water content (68.5% compared to 67.5% in the control plot) which is substantial as the mean water contents varied between 67 and 69% during the measurement period. [ABSTRACT FROM AUTHOR]

Due to their high, degree of reactivity, Mn oxides in soil systems may exert a greater influence on trace metal chemistry than that suggested by their relatively low abundance. In particular, Mn is the only known oxidizer of trivalent Cr in soils. We investigated soil properties that influence the Cr oxidizing capacity of Mn oxides in eight well-aerated high Mn soils. Total and easily reducible Mn abundance were quantified by extraction with 1.5 M NH2OH-HCl and 0.02 M hydroquinone. Relative average Mn oxidation state in soil samples was determined by x-ray absorption near edge structure spectroscopy (Mn-XANES) main edge energy position. Soils ranged in percentage of NH2OH-HCl-extractable Mn between 0.14 and 1.27, pH between 4.4 and 7.2, and percentage of C between 9.0 and 27.2. Manganese- XANES spectra showed that most of the study soils had a high Mn(IV)/Mn(III) ratio with edge energy position intermediate to that of a synthetic birnessite and a synthetic pyrolusite. In these high Mn soils, Mn-XANES edge energy was positively correlated with soil pH, suggesting a linear increase, over the normal range of soil pH, in the Mn(IV)/Mn(III) ratio of soil oxides. Soils with more total reducible Mn generally demonstrated greater net Cr(VI) production, but this pattern was moderated by soil pH and relative Mn oxidation state. High Mn soils with low pH and Mn oxidation state were weaker Cr oxidizers than their Mn abundance would suggest. Our data provide evidence that greater Mn abundance and greater Mn(IV)/Mn(III) ratio in soil Mn oxides enhances Cr oxidation. [ABSTRACT FROM AUTHOR]

Pinus pinasterseedlings were grown in a sandy dune soil either inoculated withHebeloma cylindrosporumor let to natural colonisation. Six months later, half of the seedlings of both treatments were subjected to a 3-week moderate drought. Root colonisation analysis showed that root tips were colonised to almost 100% independent of the inoculation. DNA determination of the ectomycorrhizal morphotypes showed that inoculated seedlings were extensively mycorrhized byH. cylindrosporum(more than 75%) whereas non-inoculated seedlings were mycorrhized by the exotic speciesThelephora terrestris(50%) andLaccaria bicolor(30%) and to a lesser extent byH. cylindrosporum(20%). Drought did not affect these frequencies. Total plant biomass was not affected by the mycorrhizal status or by drought but the root/shoot biomass ratio as well as the root/leaf surface area ratio were much lower in seedlings extensively colonised byH. cylindrosporum. Root hydraulic conductivity was higher in plants mainly mycorrhized byH. cylindrosporum, showing that this fungus improved the water uptake capacity of the root system as compared toT. terrestrisand/orL. bicolor. This positive effect was also found under drought but to a lesser extent.H. cylindrosporumalso increased the amount of root-adhering soil as compared to the other fungal symbionts, illustrating the performance of this association in aggregating sandy soil particles and developing the rhizosheath. The origin of the reduced root hydraulic resistance byH. cylindrosporummycorrhization is discussed for the whole path including soil, soil-root interface and root cortex. [ABSTRACT FROM AUTHOR]

Methane oxidation capacity of three soil matrices was assessed using a new method based on the pressure fall resulting from methane oxidation. The effects of incubation temperature, moisture and methane content on the oxidation capacity were studied. Parameters observed were non-methanotrophic oxygen consumption, methane assimilation, length of the lag period before steady pressure fall was reached, initial pressure fall and maximum pressure fall. Filling material taken from a biofilter was tested. The length of the lag period was an index of prior exposure of the soil to methane emissions. Incubation temperature of 30°C and soil moisture at the water-holding capacity were chosen to standardize the test. Oxygen depletion by non-methanotrophs varied between 40 and 60% of the total oxygen consumption while methane assimilation was at 40 to 50% of the total methane consumption. [ABSTRACT FROM AUTHOR]

Methanotrophic bacteria oxidize methane (CH4) in forest soils that cover ∼30% of Earth's land surface. The first measurements for a pristine Southern Hemisphere forest are reported here. Soil CH4 oxidation rate averaged 10.5±0.6 kg CH4 ha−1 yr−1, with the greatest rates in dry warm soil (up to 17 kg CH4 ha−1 yr−1). Methanotrophic activity was concentrated beneath the organic horizon at 50–100 mm depth. Water content was the principal regulator of ( r2=0.88) from the most common value of field capacity to less than half of this when the soil was driest. Multiple linear regression analysis showed that soil temperature was not very influential. However, inverse co-variability confounded the separation of soil water and temperature effects in situ. Fick's law explained the role of water content in regulating gas diffusion and substrate supply to the methanotrophs and the importance of pore size distribution and tortuosity. This analysis also showed that the chambers used in the study did not affect the oxidation rate measurements. The soil was always a net sink for atmospheric CH4 and no net CH4 (or nitrous oxide, N2O) emissions were measured over the 17-month long study. For New Zealand, national-scale extrapolation of our data suggested the potential to offset 13% of CH4 emissions from ca. 90 M ruminant animals. Our average was about 6.5 times higher than rates reported for most Northern Hemisphere forest soils. This very high was attributed to the lack of anthropogenic disturbance for at least 3000–5000 years and the low rate of atmospheric nitrogen deposition. Our truly baseline data could represent a valid preagricultural, preindustrial estimate of the soil sink for temperate latitudes. [ABSTRACT FROM AUTHOR]

Pore water has been extracted from Boom Clay by mechanical squeezing. Clay cores were obtained from various boreholes, all drilled at the SCK·CEN domain (Mol, Belgium).In contrast to pore water collected from piezometers, high sulphate concentrations are measured in the squeezed pore water. The lowest sulphate concentrations (<60 mg/l) were measured in pore waters squeezed immediately after drilling. Higher sulphate concentrations were often measured in the pore water when the clay cores were preserved for some time (generally <500 mg/l SO42−, but sometimes up to 20,000 mg/l SO42−). Nevertheless, a relation between preservation time and sulphate content could not be retrieved. However, major ion concentrations were obviously correlated with the sulphate content in the squeezed waters. The observed evolution in chemical composition were explained by water–rock interactions considering the pyrite oxidation and the subsequent ion exchange and mineral dissolution reactions. [Copyright &y& Elsevier]

Interest and the use of persulfate oxidation for the measurement of total nitrogen (N) in soil extracts and related solutions has been increasing. Persulfate has a number of advantages relative to Kjeldahl digestion including greater sensitivity, ease of use, opportunities for automation of the procedure or portion of it and reduced requirement for waste disposal. A wide variety of persulfate solution formulations and digestion conditions have been proposed and their effectiveness have been compared to other methods such as Kjeldahl, but not with each other. A study was conducted to re-examine various components of the persulfate method. The components were the composition of the oxidation solution, digestion conditions and compatibility of the digestion with quantification of the product (nitrate) of the oxidation. Tests suggested that the oxidation step was quite tolerant to the composition of the oxidant (persulfate solution) if there was sufficient to excess quantity of the oxidant to decompose organic compounds present and oxidize all resulting N compounds to nitrate, and if sufficient energy (heat) was applied. It was determined that microwaving the sample with 4% potassium persulfate oxidant in a sealed vessel for 10 minutes at 120°C was adequate. We also found that including boric acid in the oxidant as a pH buffer resulted in the solution being alkaline (pH 9) for a relatively wide range of sample matrices after the digestion was complete. Alkalinity was necessary for quantifying the resulting nitrate using flow injection analysis based on the commonly used colorimetric determination of N as nitrite after cadmium column reduction. Since the apparent recovery of organic N in solutions used for soil extractions was largely due to the effect of the cations and anions on nitrate quantification, it is essential to standardize and calibrate with an appropriate matrix of the solution containing the sample and an organic N standard through both the oxidation and quantification steps of the procedure. With these three precautions, persulfate oxidation can provide effective and efficient measurement of total N in a variety of soil extracts and related solutions. [ABSTRACT FROM AUTHOR]

Potassium ions (K+) may become “fixed” between adjacent phyllosilicate layers under waterlogged conditions, rendering K less available to plant uptake. This phenomenon was investigated under greenhouse conditions to determine if K fixation due to biogeochemical reduction contributed to the K deficiency in corn (Zea mays L.) in the northern Great Plains (South Dakota). The objective of this study was to evaluate the effects of a single reduction–oxidation (redox) event on soil K fractions and plant K uptake in montmorillonitic soils. Surface soil (Udolls, 0–15 cm) was collected from various sites across east-central South Dakota and used in a completely randomized greenhouse pot study ( 2×4 factorial). Reduced (Re) and reduced/reoxidized (Re/Ox) treatments were established, and corn was grown to the V5 stage of growth in a two cropping sequence. Potassium levels among soil K fractions did not significantly change upon the redox event. Dry matter (DM) yields were not significantly affected by the redox event. Cumulative K-uptake ranged from 25.7 to 33.2 mg K (kg soil-1), and there were no significant differences between treatments. No increase in K fixation was observed as the result of a single reduction–oxidation event. A single redox event does not cause K fixation in four montmorillonitic soils studied under greenhouse conditions. [ABSTRACT FROM AUTHOR]

A new laccase (EC 1.10.3.2) produced by Streptomyces cyaneus CECT 3335 in liquid media containing soya flour (20 g per liter) was purified to homogeneity. The physicochemical, catalytic, and spectral characteristics of this enzyme, as well as its suitability for biobleaching of eucalyptus kraft pulps, were assessed. The purified laccase had a molecular mass of 75 kDa and an isoelectric point of 5.6, and its optimal pH and temperature were 4.5 and 70°C, respectively. The activity was strongly enhanced in the presence of Cu[sup 2+], Mn[sup 2+], and Mg[sup 2+] and was completely inhibited by EDTA and sodium azide. The purified laccase exhibited high levels of activity against 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) and 2,6-dimethoxyphenol and no activity against tyrosine. The UV-visible spectrum of the purified laccase was the typical spectrum of the blue laccases, with an absorption peak at 600 nm and a shoulder around 330 to 340 nm. The ability of the purified laccase to oxidize a nonphenolic compound, such as veratryl alcohol, in the presence of ABTS opens up new possibilities for the use of bacterial laccases in the pulp and paper industry. We demonstrated that application of the laccase from S. cyaneus in the presence of ABTS to biobleaching of eucalyptus kraft pulps resulted in a significant decrease in the kappa number (2.3 U) and an important increase in the brightness (2.2%, as determined by the International Standard Organization test) of pulps, showing the suitability of laccases produced by streptomycetes for industrial purposes. [ABSTRACT FROM AUTHOR]

Elemental sulfur (S) fertilizers may cost less per unit of S than sulfate-S (SO[SUB4]-S) fertilizers, but oxidation of elemental S t o plant-available SO[SUB4]-S depends on fertilizer type and soil conditions. The objective of this study was to investigate the effects of S source, time of application, soil type and tillage on recovery of applied S as SO[SUB4]-S in fallow field soils. Field experiments were conducted at five locations on Black Chernozem (Udic Boroll), Dark Gray Chernozem (Boralfic Boroll) and Gray Luvisol (Boralfs) soils in the Parkland zone of Canadian Prairies. The recovery of <100% from previous season Na[SUB2]SO[SUB4] application in some cases indicated loss of fertilizer S from the soil SO[SUB4]-S pool. The recovery results showed that only up to 44% of the spring applied elemental S could be recovered during the same growing season. The greater recovery of spring applied elemental S in October (compared to July suggests that there is a considerable potential for SO[SUB4]-S) loss from soil over the winter and in early spring. The higher SO[SUB4]-Srecovery from Na[SUB2]SO[SUB4] compared to elemental S fertilizers Fine S, Urea S(A), Urea S) (B) and Bentonitic S (A)] following their application in the previous season showed no extra residual benefit from elemental S fertilizers relative to the SO[SUB4]-S fertilizer. Among the elemental S fertilizers, Fine S gave more recovery of SO[SUB4]-S compared to Urea S (A), Urea S (B) and Bentonitic S (A). Tillage increased SO[SUB4]-S recovery from applied S in one experiment but had inconsistent influence in another. The substantial differences in the SO[SUB4]-S recovery from different soils indicated the influence of soil type on oxidation rate and recovery of applied S at a given time. In conclusion, the findings suggest that only a portion of the applied elemental S could be recovered as SO[SUB4]-S at any of the sampling times. The recovery of residual S in the following year was always lower from... [ABSTRACT FROM AUTHOR]

It is shown that activators and mixtures of activators added to oxidation feedstock (vacuum resid) alter its colloidal structure and rheological properties. As a result, extreme values of the size of complex structural units are attained in the vacuum resid and the phase interface increases so that production of oxidized asphalts is enhanced and their quality is improved. Based on the results of industrial tests, the technology for enhancement of asphalt production is recommended for introduction. [ABSTRACT FROM AUTHOR]

Data of long-term studies are used to evaluate the rate of O2 consumption by soils in the Mozhaisk Reservoir as a function of a number of physicochemical and biological factors. Seasonal variations in the rate of O2 consumption by the soils and the relationship between these variations and the priority factors are established. [ABSTRACT FROM AUTHOR]

Changes in the isotopic composition of carbon can be used to reveal simultaneous occurrence of methane production and oxidation in soil. The method is conducted in laboratory jar experiments as well as in the field by using flux chambers. Simultaneous occurrence of production and oxidation of methane was suggested. [ABSTRACT FROM AUTHOR]

Assesses the method of separating degradation and productivity in Atlantic sediment core. Lipid contents of sediments of the f-turbidite; Degradation of organic matter (OM) at natural oxidation; Cause of enrichment in cysts in oxygen minimum zone sediments.

Determines the X-ray absorption structure spectra of soil manganese (Mn). Chemical properties of soil Mn; Oxidation state of the soil; Etiology of soil-borne plant fungal disease.

The effect of ammonium ions on the activity of methane oxidation in soils was studied. The degree of inhibition of the methanotrophic activity in the presence of ammonium in the soil solution was quantitatively assessed as dependent on ammonium concentration and the properties of different types of soils of the European part of Russia. [ABSTRACT FROM AUTHOR]

Describes the lipid and carbon isotopic evidence of methane-oxidizing and sulfate-reducing bacteria in association with gas hydrates from the gulf of Mexico. Enhancement of total biomass of phospholipids fatty acids; Effects of methane oxidation on sea-floor geology; Determination of sedimentary microbial biomass.

It is generally accepted that particulate organic matter derives from plants. In contrast, the enriched labile fraction is thought by many to derive from microbes, especially fungi. However, no detailed chemical characterization of these fractions has been done. In this study, we wanted to assess the sources (plants or microbes; fungi or bacteria) and degree of microbial alteration of (i) three particulate organic matter fractions – namely the free light fraction (1.85 g cm-3), the coarse (250–2000 μm) and the fine (53–250 μm) intra-aggregate particulate organic matter fractions – and of (ii) three density fractions of fine-silt associated carbon – namely < 2.0, 2.0–2.2 (i.e. enriched labile fraction) and > 2.2 g cm-3 – by analysing the amino sugars, by CuO oxidation analyses, and by 13C-, 1H- and 31P-NMR analyses. Macroaggregates (250–2000 μm) were separated by wet-sieving from a former grassland soil now under a no-tillage arable regime. The three particulate organic matter fractions and the three density fractions were isolated from the macroaggregates by a combination of density flotation, sonication and sieving techniques. Proton NMR spectroscopy on alkaline extracts showed that the enriched labile fraction is not of microbial origin but is strongly degraded plant material that is enriched in aliphatic moieties partly bound to aromatics. In addition, the enriched labile fraction had a glucosamine content less than the whole soil, indicating that it is not enriched in carbon derived from fungi. Decreasing yields of phenolic CuO oxidation products and increasing side-chain oxidation in the order coarse intra-aggregate particulate organic matter < fine inter-aggregate particulate organic matter < fine-silt fractions indicate progressive alteration of lignin as particle size decreases. The light fraction was more decomposed than the coarse inter-aggregate particulate organic matter, as indicated by (i) its larger ratio of acid-to-aldehyde of the vanillyl units released by CuO oxidation, (ii) the smaller contribution of H in carbohydrates to total extractable H as estimated by 1H-NMR spectroscopy, and (iii) a larger contribution of monoester P to total extractable P in the 31P-NMR spectra. In conclusion, the four fractions are derived predominantly from plants, but microbial alteration increased as follows: coarse inter-aggregate particulate organic matter < light fraction ≈ fine inter-aggregate particulate organic matter < enriched labile fraction. [ABSTRACT FROM AUTHOR]

Ammonium thiosulfate (ATS) is a popular liquid fertilizer in North America, and potassium thiosulfate (KTS) is also gaining acceptance for specialty purposes. Thiosulfate is known to oxidize rapidly in soil to tetrathionate and then to sulfate, but little information is available on the effect of temperature on these reactions. The objective of this study was to compare the rates of thiosulfate oxidation at three temperatures (5, 15, 25?C) by three soils, an Enon loamy sand from North Carolina (soil NC), an O'Neill loamy sand from Nebraska (soil NE), and a Vang loam from North Dakota (soil ND). Ammonium thiosulfate, or KTS were added at a rate of 25 mg S kg[SUP-1]. At 25°C, oxidation was very rapid, being complete after 1 or 2 weeks by all three soils. No apparent immobilization of the applied S was observed with any soil after 2 weeks of incubation. At 157deg;C, oxidation was slowed, but oxidation was still nearly complete after 2 or 3 weeks. There was some apparent S immobilization by soil NE, and to a lesser degree by soil ND at this temperature. At 5?C, the kinetics of oxidation and immobilization differed greatly between soils. With soil NC, oxidation was complete after 4 weeks, with no apparent immobilization. Soil NE exhibited a strong immobilization of the added S at 5°C, with most of the applied S remaining immobilized for 12 weeks. Soil ND was intermediate between these two soils, showing a temporary immobilization of applied thiosulfate for 26weeks, with apparent mineralization from 6-12 weeks. The effect of temperature on immobilization of S fertilizers deserves further research. [ABSTRACT FROM AUTHOR]

Examines the hydrogen peroxide effects on chromium (Cr) oxidation state and solubility in diverse, chromium-enriched soils. Effect of adding hydrogen peroxide to the surface soil at the electroplating site; Amount of Cr released by the chromium-enriched soil; Rate of Cr production in the mixtures.

Methane oxidation capacity of soil from an experimental site in Northwest England was strongly dependent on temperature and percentage water holding capacity. The soil had a distinct temperature optimum of 25 °C, with capacity for net methane oxidation being completely lost below 5 and greater than 37 °C. Optimum percentage water holding capacity for methane oxidation was in the range 30–60%, with significant reductions in methane oxidation rates in soils outside this range. Organic and mineral layers within the soil showed differences in potential methane oxidation rate, with methane oxidation being most rapid in the buried organic layer and least rapid in the surface organic layer. The importance of soil structure and gas diffusion limitation is underlined, as is the strong temperature dependence of methane oxidation when such diffusion limitation is removed. [ABSTRACT FROM AUTHOR]

Transpiration, leaf characteristics and forest structure in Metrosideros polymorpha Gaud. stands growing in East Maui, Hawaii were investigated to assess physiological limitations associated with flooding as a mechanism of reduced canopy leaf area in waterlogged sites. Whole-tree sap flow, stomatal conductance, microclimate, soil oxidation–reduction potential, stand basal area and leaf area index (LAI) were measured on moderately sloped, drained sites with closed canopies (90%) and on level, waterlogged sites with open canopies (50–60%). The LAI was measured with a new technique based on enlarged photographs of individual tree crowns and allometric relationships. Sap flow was scaled to the stand level by multiplying basal area—normalized sap flow by stand basal area. Level sites had lower soil redox potentials, lower mean stand basal area, lower LAI, and a higher degree of soil avoidance by roots than sloped sites. Foliar nutrients and leaf mass per area (LMA) in M. polymorpha were similar between level and sloped sites. Stomatal conductance was similar for M. polymorpha saplings on both sites, but decreased with increasing tree height (r2 = 0.72; P < 0.001). Stand transpiration estimates ranged from 79 to 89% of potential evapotranspiration (PET) for sloped sites and from 28 to 51% of PET for level sites. Stand transpiration estimates were strongly correlated with LAI (r2 = 0.96; P < 0.001). Whole-tree transpiration was lower at level sites with waterlogged soils, but was similar or higher for trees on level sites when normalized by leaf area. Trees on level sites had a smaller leaf area per stem diameter than trees on sloped sites, suggesting that soil oxygen deficiency may reduce leaf area. However, transpiration per unit leaf area did not vary substantially, so leaf-level physiological behavior was conserved, regardless of differences in tree leaf area. [ABSTRACT FROM AUTHOR]

Examines iron oxidation states on root surfaces of the common reed, Phragmites australis. Effects of iron sources on iron oxidation states; Iron oxidation states in different root zones; Iron accumulation model.

Methane fluxes were measured, using static chambers, across a disturbance gradient in a West African semi-deciduous humid forest. Soil-feeding termite biomass was simultaneously determined, in an attempt to examine its influence on the net soil-atmosphere exchange of CH4. CH4 emission rates from individual termite species were determined under laboratory conditions, permitting the gross production of CH4 to be compared with net fluxes to the atmosphere. Both net CH4 oxidation(-) and emission were observed, and CH4 fluxes ranged from – 24.6 to 40.7 ng m–2 s–1. A statistically significant relationship between termite biomass and CH4 flux was observed across the forested sites such that: CH4 flux (ng m–2 s–1) = 4.95 × termite biomass (gm–2) – 10.9 (P < 0.001). Rates of CH4 oxidation were on average 60% smaller at the clearfelled and Terminalia plantation sites than at the near-primary forest site. Two of the disturbed sites were net CH4 sources during one of the sampling periods. Disturbance of tropical forests, resulting in a decrease in the CH4 sink capacity of the soil, may therefore increase the contribution of termite-derived CH4 to the atmosphere. Measurements from the mounds of the soil-feeding termites Thoracotermes macrothorax and Cubitermes fungifaber from the old plantation site gave a CH4 emission of 636 and 53.4 ng s–1 mound–1, respectively. The forest floor surrounding the mounds was sampled in three concentric bands. Around the mound of T. macrothorax the soil was a net source of CH4 estimated to contribute a further 148 ng s–1. Soil surrounding the mound of C. fungifaber was mostly a net sink. The mounds of soil-feeding termites are point sources of... [ABSTRACT FROM AUTHOR]

In recent years great advances in the understanding of photosystem II have been achieved. The process of photochemical charge separation seems to be fairly well understood, while the identity of the water oxidizing enzyme in photosystem II has remained uncertain. In the first part of the paper a brief review on structural and functional aspects of photosystem II is given, and in the second part the nature of the elusive water oxidizing enzyme is considered. Two models are discussed. The first model, favoured by the majority of groups working in this area, suggests that the reaction center polypeptide D1 (in association with other known photosystem 11 polypeptides) is the site of water oxidation. The second model, mainly based on our results with cyanobacteria, predicts that the water oxidizing enzyme is a separate polypeptide in the 30 kDa region, distinct from D1 and D2, in addition, to the seven polypeptides so far recognized in minimal O2 evolving photosystem II complexes. [ABSTRACT FROM AUTHOR]

Describes the design of a polarographic assembly for multiple sampling of soil oxygen flux in the field. Outline of the sampling procedure used; Use of the equipment to monitor soil-oxidation-reduction potentials; Determination of the effective voltage of the equipment; Basis of the platinum-microelectrode technique on the reduction of oxygen at a platinum-wire cathode buried in the soil.

The article examines the influence of commercial formulations of two widely use insecticides, hexachlorocyclohexane and carbofuran on methane oxidation in a flooded rice soil. It is said that most commonly used pesticides in agriculture are seldom toxic at a recommended level and environmental safety. The study conducted, will provide an important information regarding the used of such pesticides to rice soils and its atmospheric effect. Methods involve several soil testing at different processes with designated chemicals compounds. After careful experimentation, results suggests that the application of hexacyclohexane to a soil at a recommended level had retarded methane oxidation while carbofuran had stimulated the methane oxidation.

The article discusses the result of the study conducted regarding the oxidation-reduction reaction of soil particles. The spectroscopic study of soil particles have been sought to be an important factor in examining site contamination or potential toxic effects of the chemicals. However, the oxidation state of such chemicals has been found to influence its solubility, mobility as well as its toxicity. Furthermore, the quantitative investigation of the redox reactions in soil have been found to be disadvantageous for the lack of reliable analytical methods in studying reactions as well as the heterogeneity of the mineral components and redox systems in nature.

The article presents a study of the concentrations of arsenic (As) and zinc (Zn) in ironplaque, rhizosphere and bulk soil of wetland plants such as Spartina anglica and Halimione portulacoides. The study uses Pye Unicam SP9 flame atomic absorption spectrophotometer (FAAS) to analyze the accumulation of As, iron (Fe) and Zn in soils. Results suggest that the effects of plants on metal retention by wetlands can be through oxidation of rhizosphere that increases iron oxyhydroxides in soil.

Plants of saline habitats can encounter anoxic conditions to extents which vary with habitat and life form. Rhizophytes (with roots or rhizoids in a sediment) routinely have anoxia or hypoxia in their roots, rhizoids and rhizomes. Haptophytes (attached to large particles of substrate) and planophytes (unattached) are generally less prone to anoxia or hypoxia, exceptions being ice-encased polar haptophytes and estuarine and muddy shore macroscopic planophytes (pleustophytes) which can become hypoxic or anoxic as a result of burial in sediment or under new growth.A major difference between anoxia in low-salinity habitats and anoxia in saline habitats is the presence of high sulphate concentrations in most saline habitats including seawater. Use of sulphate as electron acceptor in microbial oxidation or organic carbon produces sulphide, with relatively less production of methane than in anoxic habitats with lower sulphate concentrations. In addition to its role as a toxin. 34S/32S natural abundance data show that 34S-depleted sulphide is directly or indirectly used as a sulphur source for roots and rhizomes of seagrasses and for the whole organism of emergent salt marsh herbs and mangroves. Granted the presence of hydrogen sulphide in the rhizosphere, its entry by lipid-solution permeation of the plasmalemma is inevitable. The balance of evidence favours the entry of hydrogen sulphide rather than the oxidation of 34S-depleted sulphide to 34S-depleted sulphate in an aerobic rhizosphere with subsequent entry of sulphate. [ABSTRACT FROM AUTHOR]

In West Sumatra, Indonesia, a high-yield perennial rice cropping method called SALIBU was recently reported, in which the most unique feature is double cutting (DC) at harvest and after harvest. The objective of this study was to verify the ratooning rice yield under the SALIBU system in Myanmar. Two cultivation trials consisting of two cutting and three moisture treatments were conducted in 2019 and 2020. We concluded that double cutting had no positive effect on grain yield and regeneration rate compared with single cutting (SC). For the cutting regime, significant results were detected in the ratoon crops on yield components, but all of these were negative effects of DC, and were statistically lower than those of SC. On the other hand, a significant positive effect of moisture regime on grain yield in all ratoons was observed. The grain yield of the dry regime was significantly increased by 69% compared with that of the saturated regime. Soil oxidation conditions during the initial growth period of ratoons could contribute to the improved yield performance of the ratoons. [ABSTRACT FROM AUTHOR]

The oxidation of para-nitrochlorobenzene (pNCB) by persulfate (PS) activated with zero-valent iron (Fe0) was investigated through a series of batch experiments. The pNCB reduction ratio increased with the decrease of the initial solution pH. It is found that temperature and Fe0 dosage could also influence the pNCB removal. Under the conditions of initial Fe0 dosage 0.8 mmol/g, initial pH of 6.6, and 25 °C, 66.3% of pNCB was reduced in 6 h. The pNCB was slightly degraded in the presence of PS alone. When PS was dosed after 2 h of Fe0 reduction, significantly higher pNCB removal (94.1%) and mineralization (36.4%) were obtained relative to the case of simultaneous dosing of Fe0 and PS (85.3% removal, 22.6% mineralization). This indicates that the reduction product of pNCB was more easily oxidized by PS than pNCB, suggesting that converting the nitro groups of pNCB to amino groups prior to oxidation can enhance their oxidation. These results suggest that a sequential Fe0 reduction-PS oxidation process may be an effective strategy to promote pNCB decomposition in contaminated soil. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented offering information on the relationship between soil methane oxidation and other carbon compounds.