首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.

Background and aims

Recent research has demonstrated the high accuracy of a new method for assessment of plant available P in soil called diffusive gradients in thin-films (DGT). The process of P released by additions of bicarbonate to soil samples simulating common soil P tests is yet to be assessed by the new method (DGT). The aim of this study was to identify the pools of soil P extracted by soil test methods (DGT, Colwell and resin) by comparing, in 32P–labelled soils, the specific activity (SA) of phosphorus extracted by common soil test extracts with the SA of wheat plants grown in a range of agricultural soils from southern Australia.

Methods

Wheat (cv. Frame) was grown for 4 weeks in 14 soils that were labelled uniformly with carrier-free 32P. The specific activity (SA) of P (MBq 32P kg 31P?1) in each soil test extract was compared to the SA of P in the wheat plants.

Results

The SA of P in plants were similar to P extracted by the Colwell extractant in only 4 of the 14 soils; while SA in plants and extractants corresponded in 10 of the soils for the resin method and in 12 of the soils for the DGT method. Phosphorus in the Colwell and resin extract solutions had significantly lower SAs compared to P in the plants for 10 and 4 of the soils, respectively, indicating greater extraction of non-labile P sources (unlabelled 31P). Phosphorus in the DGT extractant had significantly lower SA than the plants for 1 soil and in 1 soil the SA was higher. Overall, across all soils, 25 % of P extracted by the Colwell method was non labile compared to 9 % and 2 % for the resin and DGT methods, respectively.

Conclusion

The new DGT method for extraction of soil P has the potential to accurately predict occurrences of P deficiency because it generally extracts the same pool of labile soil P accessed by wheat plants, while methods using bicarbonate solution (e.g. Colwell, Olsen) or water (resin) at wide soil:solution ratios are more likely to measure more non-labile forms of P in soil.  相似文献   

2.
Burkholderia sp. F24, originally isolated from soil, was capable of growth on xylose and removed organic inhibitors present in a hemicellulosic hydrolysate and simultaneously produced poly-3-hydroxybutyrate (P3HB). Using non-detoxified hydrolysate, Burkholderia sp. F24 reached a cell dry weight (CDW) of 6.8 g L?1, containing 48 % of P3HB and exhibited a volumetric productivity (PP3HB) of 0.10 g L?1 h?1. Poly-3-hydroxybutyrate-co-3-hydroxyvalerate copolymers (P3HB-co-3HV) were produced using xylose and levulinic acid (LA) as carbon sources. In shake flask cultures, the 3HV content in the copolymer increased from 9 to 43 mol% by adding LA from 1.0 to 5.0 g L?1. In high cell density cultivation using concentrated hemicellulosic hydrolysate F24 reached 25.04 g L?1 of CDW containing 49 % of P3HB and PP3HB of 0.28 g L?1 h?1. Based on these findings, second-generation ethanol and bioplastics from sugarcane bagasse is proposed.  相似文献   

3.
Batch experiments were performed for the aerobic co-metabolism of 1,1-dichloroethylene (1,1-DCE) by Achromobacter sp., identified by gene sequencing of 16S rRNA and grown on benzene. Kinetic models were employed to simulate the co-metabolic degradation of 1,1-DCE, and relevant parameters were obtained by non-linear least squares regression. Benzene at 90 mg L?1 non-competitively inhibited degradation of 1,1-DCE (from 125 to 1,200 μg L?1). The maximum specific utilization (kc) rate and the half-saturation constant (Kc) for 1,1-DCE were 54 ± 0.85 μg h?1 and 220 ± 6.8 μg L?1, respectively; the kb and Kb for benzene were 13 ± 0.18 mg h?1 and 28 ± 0.42 mg L?1, respectively. This study provides a theoretical basis to predict the natural attenuation when benzene and 1,1-DCE occur as co-contaminants.  相似文献   

4.
Anthropogenic pollutants and climate change are major threats to coral reefs today. Yet interactions between chemical and thermal perturbations have not been fully explored in reef studies. Here, we present the single and combined effects of copper (Cu) with thermal stress on five early life-history stages/processes (fertilization, larval mortality, swimming ability, metamorphosis and growth of juvenile recruits) of the massive coral Platygyra acuta in Hong Kong. In the first four experiments, coral gametes and larvae were exposed to different Cu doses (0–200 μg L?1, apart from the fertilization assay in which 0–1000 μg L?1 was used) and temperature treatments (ambient and ambient +2 or +3 °C as a thermal stress treatment) following a factorial experimental design. Exposure time was 5 h for the fertilization assay and 48 h for the other experiments. The last experiment on growth of coral recruits was conducted over 56 d with 0–80 μg L?1 Cu used. Cu significantly reduced percent fertilization success, percentage of active swimming larvae and larval survivorship (EC50s, the half maximal effective concentrations, for percent fertilization success and percentage of active swimming larvae were 92–145 and 45–47 μg L?1 respectively. While LC50, the lethal concentration that kills 50% of the population, was 101–110 μg L?1), while growth of coral recruits was not affected at 80 μg L?1 Cu for 56 d. No settling cues were used in the settlement experiment. In their absence, percent metamorphosis increased with Cu doses, in sharp contrast to earlier findings. Settlement and metamorphosis may thus be strategies for coral larvae to escape from Cu toxicity. Thermal treatment did not significantly affect any experimental end points. This is likely because the thermal regimes used in the experiments were within the range experienced by local corals. The high variability in Cu toxicities indicates differential susceptibilities of the various life-history stages/processes of P. acuta. The level of Cu tolerance was also markedly higher than that reported in the literature for other coral species. This provides evidence to suggest possible adaptation of this species to survive in a highly polluted marine environment like that in Hong Kong.  相似文献   

5.
Citric acid was produced by five species of the yeast Candida after growth on a medium containing soy biodiesel-based crude glycerol. After growth on a medium containing 10 g L?1 or 60 g L?1 crude glycerol for 168 hr at 30°C, Candida parapsilosis ATCC 7330 and C. guilliermondii ATCC 9058 produced the highest citric acid levels. On 10 g L?1 or 60 g L?1 crude glycerol for 168 hr at 30°C, the citric acid level produced by C. parapsilosis ATCC 7330 was 1.8 g L?1 or 11.3 g L?1, respectively, while C. guilliermondii ATCC 9058 produced citric acid concentrations of 3.0 g L?1 or 10.4 g L?1, respectively. Biomass production by C. guilliermondii ATCC 9058 on 10 g L?1 or 60 g L?1 crude glycerol for 168 hr at 30°C was highest at 1.2 g L?1 or 6.9 g L?1, respectively. The citric acid yields observed for C. guilliermondii ATCC 9058 after growth on 10 g L?1 or 60 g L?1 crude glycerol (0.35 g g?1 or 0.21 g g?1, respectively) were generally higher than for the other Candida species tested. When similar crude glycerol concentrations were present in the culture medium, citric acid yields observed for some of the Candida species utilized in this study were about the same or higher compared to citric acid yields by Yarrowia lipolytica strains. Based on the findings, it appeared that C. guilliermondii ATCC 9058 was the most effective species utilized, with its citric acid production being similar to what has been observed when citric acid-producing strains of Y. lipolytica were grown on crude glycerol under batch conditions that could be of significance to biobased citric acid production.  相似文献   

6.
Many terrestrial soils in the US Midwest are temporally flooded during the spring. The effects of short-term flooding on biogeochemical processes that occur in these soils are not fully understood and are the subject of this study. To evaluate these processes we investigated the redox-induced changes in the soil solution for three-cultivated and three-uncultivated/forest soils with different organic matter concentrations. The soils were flooded for 1, 3, 7, and 14-days under anoxic conditions in a biogeochemical reactor. Samples were analyzed for Eh; pH; NO3 ?; NH4 +; total dissolved Mn and Fe; soluble P; dissolved organic and inorganic carbon (DOC–DIC); and evolved CO2. We found strongly contrasting responses of the terrestrial soils to flooding. Reducing conditions were established quickly in the uncultivated and more slowly in the cultivated soils. Concomitant changes in pH were higher for the uncultivated soils. The uncultivated soils showed a higher increase in the amount of NH4 +, P, Fe, Mn than the cultivated soils over the 14-day incubation. The total amount of carbon decomposed was much greater for the uncultivated soils with approximately 900 μg C (CO2 + DOC + DIC) decomposed per gram of soil compared to a total decomposition of 240 μg C g soil ?1 for the cultivated soils indicating differences in the type of carbon decomposed. The rapid onset of reducing conditions for the uncultivated soils is attributed to a reactive carbon component that is either absent or occluded in the cultivated soils. This study demonstrates that the biogeochemically-induced changes in carbon dynamics in terrestrial soils are strongly influenced by short-term flooding and the history of soil management.  相似文献   

7.
Marie Spohn  Luise Giani 《Plant and Soil》2011,338(1-2):183-192
Soil organic carbon stocks decrease after conversion of soils from pasture to cropland. It has been assumed that this applies especially to mineral hydromorphic soils. In this paper we evaluate hot-water extractable carbon (Chwe) as a measure for detecting long-term changes in the SOM following land use change. Furthermore, we assess whether a treatment of the soils with NaOCl leads to the isolation of long-term stable C fractions. For these purposes, we established a chronosequence of sandy hydromorphic soils that have been converted from pasture to cropland at different periods of history. To gain further insight into the impacts of different types of land use on carbon sequestration, soils under forest, either afforested or permanent, were studied. Bulk density, total organic carbon (TOC), Chwe, and NaOCl-resistant C were quantified in the surface soils of 72 Gleyic Podzols and Haplic Gleysols. The bulk density increased from 0.9 (±0.2) g cm?3 to 1.4 (±0.1) g cm?3 during the first 25 years after the conversion of the soils from permanent pasture to cropland. In the permanent pasture sites, the TOC concentration amounted to 35.4 (±12.1) g kg?1. It decreased to 12.88 (±5.9) g kg?1 during the first 46 years of cultivation (R2?=?0.71). In the permanent forest soils the TOC concentrations were significantly higher than in the soils that have been afforested. Chwe concentrations of the chronosequence sites were linearly correlated to the TOC concentrations (R2?=?0.84), while permanent forest sites exhibited significantly higher Chwe/TOC ratios. This shows that the determination of the Chwe is a very promising measure for detecting changes in SOM dynamics following afforestation. In the permanent pasture sites, 14.3 (±5.38) g kg?1 NaOCl-resistant C was measured, while 46 years after conversion, only 2.8 (±1.2) g kg?1remained. No enrichment of NaOCl-resistant C was observed in the chronosequence, as NaOCl-resistant C decreased faster in the course of cultivation than the TOC. Therefore, we conclude that that the C fraction that resists the oxidation with NaOCl is not long-term stable in soils, and most probably, there is no such long-term stable C fraction in the soils under study.  相似文献   

8.
This study, comprising three independent experiments, was conducted to optimize the zinc (Zn) application through seed coating for improving the productivity and grain biofortification of wheat. Experiment 1 was conducted in petri plates, while experiment 2 was conducted in sand-filled pots to optimize the Zn seed coating using two sources (ZnSO4, ZnCl2) of Zn. In the first two experiments, seeds of two wheat cultivars Lasani-2008 and Faisalabad-2008 were coated with 0.25, 0.50, 0.75, 1.00, 1.25, 1.50, 1.75 and 2.00 g Zn kg?1 seed using ZnSO4 and ZnCl2 as Zn sources. The results of experiment I revealed that seed coating with 1.25 and 1.50 g Zn kg?1 seed using both sources of Zn improved the seedling emergence. However, seed coated with 1.25 and 1.50 g Zn kg?1 seed using ZnSO4 was better regarding improvement in seedling growth and seedling dry weight. The results of the second experiment indicated that seed coated with 1.25 and 1.50 g Zn kg?1 seed using ZnSO4 improved the seedling emergence and seedling growth of tested wheat cultivars. However, seed coating beyond 1.5 g Zn kg?1 seed using either Zn source suppressed the seedling emergence. Third experiment was carried out in glass house in soil-filled earthen pots. Seeds of both wheat cultivars were coated with pre-optimized treatments (1.25, 1.50 g Zn kg?1 seed) using both Zn sources. Seed coating with all treatments of ZnSO4 and seed coating with 1.25 g Zn kg?1 seed using ZnCl2 improved the seedling emergence and yield-related traits of wheat cultivars. Seed coating with 1.25 g Zn kg?1 seed also improved the chlorophyll a and b contents. Maximum straw Zn contents, before and after anthesis, were recorded from seed coated with 1.5 g Zn kg?1 seed using either Zn source. Increase in grain yield from seed coating followed the sequence 1.25 g Zn kg?1 seed (ZnSO4) >1.25 g Zn kg?1 seed (ZnCl2) >1.5 g Zn kg?1 seed (ZnSO4). However, increase in grain Zn contents from seed coated was 1.5 g Zn kg?1 seed (ZnCl2) >1.25 and 1.5 g Zn kg?1 seed (ZnCl2, ZnSO4) >1.25 g Zn kg?1 seed (ZnSO4). Seed coating with Zn increased the grain Zn contents from 21 to 35 %, while 33–55 % improvement in grain yield was recorded. In conclusion, wheat seeds may be coated with 1.25 g Zn kg?1 seed using either source of Zn for improving the grain yield and grain Zn biofortification.  相似文献   

9.
We determined fatty acid (FA) profiles and carbon stable isotopic composition of individual FAs (δ13CFA values) from sea ice particulate organic matter (i-POM) and pelagic POM (p-POM) in the Bering Sea during maximum ice extent, ice melt, and ice-free conditions in 2010. Based on FA biomarkers, differences in relative composition of diatoms, dinoflagellates, and bacteria were inferred for i-POM versus p-POM and for seasonal succession stages in p-POM. Proportions of diatom markers were higher in i-POM (16:4n-1, 6.6–8.7 %; 20:5n-3, 19.6–25.9 %) than in p-POM (16:4n-1, 1.2–4.0 %; 20:5n-3, 5.5–14.0 %). The dinoflagellate marker 22:6n-3/20:5n-3 was highest in p-POM. Bacterial FA concentration was higher in the bottom 1 cm of sea ice (14–245 μg L?1) than in the water column (0.6–1.7 μg L?1). Many i-POM δ13CFA values were higher (up to ~10 ‰) than those of p-POM, and i-POM δ13CFA values increased with day length. The higher i-POM δ13CFA values are most likely related to the reduced dissolved inorganic carbon (DIC) availability within the semi-closed sea ice brine channel system. Based on a modified Rayleigh equation, the fraction of sea ice DIC fixed in i-POM ranged from 12 to 73 %, implying that carbon was not limiting for primary productivity in the sympagic habitat. These differences in FA composition and δ13CFA values between i-POM and p-POM will aid efforts to track the proportional contribution of sea ice algal carbon to higher trophic levels in the Bering Sea and likely other Arctic seas.  相似文献   

10.
The technique of near and short wave near-infrared spectroscopy was assessed with respect to analysis of dry matter and lipid content of microalgae with potential for biodiesel production. Microalgal culture samples were filtered through GF/C filter papers and spectral measurements of wet and oven dried (60 °C overnight) filter papers over the ranges of 300–1,100 nm and 1,100–2,500 nm were recorded. Partial least square models on culture biomass and lipid content for combined species data were poor in terms of RMSECV, R CV and the ratio of RMSECV to SD. A single species model for C. vulgaris based on 1,100–2,500 nm spectra of dry filtrate supported a model with RMSECV, R CV and SDR values of 0.32 g L?1, 0.955 and 3.38 for biomass and 0.089 g L?1, 0.874 and 2.06 with lipid, respectively. However, the dry filtrate models on biomass and lipid content performed poorly in the prediction of samples drawn from an independent series of C. vulgaris cultured under N-, P- and Fe-limited growth trial. Thus, while the near-infrared spectroscopy technique has potential for assessment of dry matter and lipid content of microalgal cultures using a dried filtrate sample, further work is required to examine the limits to model robustness.  相似文献   

11.
Nutrient biogeochemistry associated with the early stages of soil development in deltaic floodplains has not been well defined. Such a model should follow classic patterns of soil nutrient pools described for alluvial ecosystems that are dominated by mineral matter high in phosphorus and low in carbon and nitrogen. A contrast with classic models of soil development is the anthropogenically enriched high nitrate conditions due to agricultural fertilization in upstream watersheds. Here we determine if short-term patterns of soil chemistry and dissolved inorganic nutrient fluxes along the emerging Wax Lake delta (WLD) chronosequence are consistent with conceptual models of long-term nutrient availability described for other ecosystems. We add a low nitrate treatment more typical of historic delta development to evaluate the role of nitrate enrichment in determining the net dinitrogen (N2) flux. Throughout the 35-year chronosequence, soil nitrogen and organic matter content significantly increased by an order of magnitude, whereas phosphorus exhibited a less pronounced increase. Under ambient nitrate concentrations (>60 μM), mean net N2 fluxes (157.5 μmol N m?2 h?1) indicated greater rates of gross denitrification than gross nitrogen fixation; however, under low nitrate concentrations (<2 μM), soils switched from net denitrification to net nitrogen fixation (?74.5 μmol N m?2 h?1). As soils in the WLD aged, the subsequent increase in organic matter stimulated net N2, oxygen, nitrate, and nitrite fluxes producing greater fluxes in more mature soils. In conclusion, soil nitrogen and carbon accumulation along an emerging delta chronosequence largely coincide with classic patterns of soil development described for alluvial floodplains, and substrate age together with ambient nitrogen availability can be used to predict net N2 fluxes during early delta evolution.  相似文献   

12.
Studies were performed on the effect of CaCO3 and CaCl2 supplementation to fermentation medium for ethanol production from xylose, glucose, or their mixtures using Scheffersomyces (Pichia) stipitis. Both of these chemicals were found to improve maximum ethanol concentration and ethanol productivity. Use of xylose alone resulted in the production of 20.68 ± 0.44 g L?1 ethanol with a productivity of 0.17 ± 0.00 g L?1 h?1, while xylose plus 3 g L?1 CaCO3 resulted in the production of 24.68 ± 0.75 g L?1 ethanol with a productivity of 0.21 ± 0.01 g L?1 h?1. Use of xylose plus glucose in combination with 3 g L?1 CaCO3 resulted in the production of 47.37 ± 0.55 g L?1 ethanol (aerobic culture), thus resulting in an ethanol productivity of 0.39 ± 0.00 g L?1 h?1. These values are 229 % of that achieved in xylose medium. Supplementation of xylose and glucose medium with 0.40 g L?1 CaCl2 resulted in the production of 44.84 ± 0.28 g L?1 ethanol with a productivity of 0.37 ± 0.02 g L?1 h?1. Use of glucose plus 3 g L?1 CaCO3 resulted in the production of 57.39 ± 1.41 g L?1 ethanol under micro-aerophilic conditions. These results indicate that supplementation of cellulosic sugars in the fermentation medium with CaCO3 and CaCl2 would improve economics of ethanol production from agricultural residues.  相似文献   

13.
Soil microbial biomass C (Cmic) is a sensitive indicator of trends in organic matter dynamics in terrestrial ecosystems. This study was conducted to determine the effects of tropospheric CO2 or O3 enrichments and moisture variations on total soil organic C (Corg), mineralizable C fraction (CMin), Cmic, maintenance respiratory (qCO2) or Cmic death (qD) quotients, and their relationship with basal respiration (BR) rates and field respiration (FR) fluxes in wheat‐soybean agroecosystems. Wheat (Triticum aestivum L.) and soybean (Glycine max. L. Merr) plants were grown to maturity in 3‐m dia open‐top field chambers and exposed to charcoal‐filtered (CF) air at 350 μL CO2 L?1; CF air + 150 μL CO2 L?1; nonfiltered (NF) air + 35 nL O3 L?1; and NF air + 35 nL O3 L?1 + 150 μL CO2 L?1 at optimum (? 0.05 MPa) and restricted soil moisture (? 1.0 ± 0.05 MPa) regimes. The + 150 μL CO2 L?1 additions were 18 h d?1 and the + 35 nL O3 L?1 treatments were 7 h d?1 from April until late October. While Corg did not vary consistently, CMin, Cmic and Cmic fractions increased in soils under tropospheric CO2 enrichment (500 μL CO2 L?1) and decreased under high O3 exposures (55 ± 6 nL O3 L?1 for wheat; 60 ± 5 nL O3 L?1 for soybean) compared to the CF treatments (25 ± 5 nL O3 L?1). The qCO2 or qD quotients of Cmic were also significantly decreased in soils under high CO2 but increased under high O3 exposures compared to the CF control. The BR rates did not vary consistently but they were higher in well‐watered soils. The FR fluxes were lower under high O3 exposures compared to soils under the CF control. An increase in Cmic or Cmic fractions and decrease in qCO2 or qD observed under high CO2 treatment suggest that these soils were acting as C sinks whereas, reductions in Cmic or Cmic fractions and increase in qCO2 or qD in soils under elevated tropospheric O3 exposures suggest the soils were serving as a source of CO2.  相似文献   

14.
The Middle Route of the South-to-North Water Diversion Project is a significant water diversion project intended to alleviate water shortages in the north China plains, especially for the capital (Beijing). After water retention, the potential ecological risk of metal contamination in the riparian soils of the Miyun Reservoir (MYR) to water quality has raised public concern. The remobilization characteristics of cobalt (Co) in MYR riparian soils are still unknown. Riparian soil samples (considering five different land use types and three vertical elevations) were collected from the MYR prior to water impoundment. Total Co concentrations, soil properties, total Co in soil solution, Co chemical fractions and labile Co measured by diffusive gradients in thin films (DGT) are applied to investigate the Co remobilization characteristics. The results showed that the total concentrations of Co (Ctotal-Co) were approximately equal to background values of Co in Beijing and China at most of the sites. The highest values of Ctotal-Co were observed at 140 m and 145 m in recreational land (S3), which may be influenced by the anthropogenic activities. No obvious differences in Ctotal-Co and DGT-labile Co (CDGT-Co) were found with the variation of land use types and vertical elevations in the soils of the MYR. CDGT-Co made up 9%-52% of the total dissolved Co, with an average value of 25%, indicating that Co in the soil solution was partially sustained by the solid phase. The highest CDGT-Co were observed in grassland and mountain land, indicating that the previous intensive mining in the upstream areas of the MYR is responsible for the release of Co. The results of the sequential extraction showed that Co is mainly bound to the residual fraction. DGT-labile Co had no correlation with non-residual fractions measured by sequential extraction, but had a significantly positive relationship with CDGT-Mn, indicating that Co trapped by DGT mainly came from the dissolution of MnOx. When the MYR riparian soils are submerged, a reducing environment will be formed. In this case, Co associated with MnOx may be also released into the water.  相似文献   

15.
Conversion, drainage, and cultivation of tropical peatlands can change soil conditions, shifting the C balance of these systems, which is important for the global C cycle. We examined the effect of soil organic matter (SOM) quality and nutrients on CO2 production from peat decomposition using laboratory incubations of Indonesian peat soils from undrained forest in Kalimantan and drained oil palm plantations in Kalimantan and Sumatra. We found that oil palm soils had higher C/N and lower SOM quality than forest soils. Higher substrate quality and nutrient availability, particularly lower ratios of aromatic/aliphatic carbon and C/N, rather than total SOM or carbon, explained the higher rate of CO2 production by forest soils (10.80 ± 0.23 µg CO2–C g C h?1) compared to oil palm soils (5.34 ± 0.26 µg CO2–C g C h?1) from Kalimantan. These factors also explained lower rates in Sumatran oil palm (3.90 ± 0.25 µg CO2–C g C h?1). We amended peat with nitrogen (N), phosphorus (P), and glucose to further investigate observed substrate and nutrient constraints across the range of observed peat quality. Available N limited CO2 production, in unamended and amended soils. P addition raised CO2 production when substrate quality was high and initial P state was low. Glucose addition raised CO2 production in the presence of added N and P. Our results suggest that decline in SOM quality and nutrients associated with conversion may decrease substrate-driven rates of CO2 production from peat decomposition over time.  相似文献   

16.
Photosynthetic bacteria are known to utilize volatile fatty acids as a carbon source for growth and product formation. In this study, a new isolate, Rubrivivax benzoatilyticus PS-5, possessing self-flocculation properties, was cultivated in modified glutamate-malate (GM) medium containing glutamate and malate as carbon sources. The effect of acetic acid, propionic acid and butyric acid (at 1–4 g L?1) as co-substrates and 7.5 mM glycine, 10 mM succinic acid as precursors for 5-aminolevulinic acid (ALA) production from R. benzoatilyticus PS-5 was investigated. Among the volatile fatty acids tested, acetic acid was preferred to butyric acid and propionic acid, with the optimum concentrations of 3 g L?1, 1 g L?1 and 3 g L?1, respectively. The highest ALA production was 169.71 μM, 162.16 μM and 46.18 μM, respectively, while the highest productivity was 2.57 μM h?1, 2.25 μM h?1 and 0.96 μM h?1, respectively. The precursor was consumed completely (100 %) while the assimilation of the acetic acid and butyric acid was 62.50 % and 48.65 %, respectively. Supplementation of propionic acid (at 1–4 g l?1) had a negative effect on growth and ALA production. To increase production efficiency, the pH-control strategy (at pH 6.0–8.0) during fermentation was tested. The optimum pH was 7.0, giving the maximum ALA production of 286.18 μM and a productivity of 3.97 μM h?1. These values were 1.68-fold and 1.54-fold higher, respectively, than those under uncontrolled pH conditions.  相似文献   

17.

Aims

Phytomanagement of metal-polluted soils requires information on plant responses to metal availability in soil, but the predictability of metal accumulation in plant shoots and/or roots may be limited by metal toxicity and inherent shortfalls of the bioavailability assays.

Methods

We measured the uptake of Cd and Zn in a Salix smithiana clone grown in a pot experiment on soils with different characteristics and metal availabilities, determined by conventional soil single extractions (0.05 M Na2-EDTA and 1 M NH4NO3), soil solution obtained by centrifugation, and diffusive gradients in thin films (DGT). The Cd and Zn phytoavailability after a 2-year phytoextraction by willow was assessed by metal accumulation in the straw of the following barley culture.

Results

The phytoextraction efficiency was largest on a moderately polluted acid soil. Biomass and shoot Zn concentrations of S. smithiana were better predicted by DGT-measured Zn concentrations in soil solution (C DGT) than by Zn concentrations in the soil solution and extractable soil fractions. The weaker correlation for Cd in shoots may be related to relative Cd enrichment in the plant tissues. The metal accumulation in barley straw was unaffected or increased after a 2-year phytoextraction.

Conclusions

The shoot Zn and Cd removal of the tested Salix clone can be predicted by C DGT concentrations and is highest on either calcareous or moderately polluted acid soils. Single extraction with NH4NO3 and the C DGT value of Cd were not able to predict shoot Cd removal on the tested soils. Only shoot removal of Zn was predicted fairly well by the C DGT value.  相似文献   

18.
The new paradigm is to view wastes as resources for sustainable development. In this regard, the feasibility of poultry waste and CO2 utilization for cultivation of a filamentous nitrogen-fixing cyanobacterium, Nostoc muscorum Agardh, was investigated for production polyhydroxyalkanoates, the biodegradable polymers. This cyanobacterium showed profound rise in biomass yield with up to 10 % CO2 supply in airstream with an aeration rate of 0.1 vvm. Maximum biomass yield of 1.12 g L?1 was recorded for 8 days incubation period, thus demonstrating a CO2 biofixation rate of 0.263 g L?1 day?1 at 10 % (v/v) CO2-enriched air. Poultry litter (PL) supplementation also had a positive impact on the biomass yield. The nutrient removal efficiency of N. muscorum was reflected in the significant reduction in nutrient load of PL over the experimental period. A maximum poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) [P(3HB-co-3HV)] copolymer yield of 774 mg L?1 (65 % of dry cell wt.), the value almost 11-fold higher than the control, was recorded in 10 g L?1 PL-supplemented cultures with 10 % CO2 supply under the optimized condition, thus demonstrating that N. muscorum has good potential for CO2 biomitigation and poultry waste remediation while simultaneously producing eco-friendly polymers.  相似文献   

19.
The Antarctic continent is one of the most protected areas on the planet, but is dynamically responding to environmental change on a global scale. Change in the air temperature may affect the organic matter production in the area. Biomarkers such as sterols, n-alkanols and phytol in three sediment cores from Admiralty Bay, Antarctica, were determined to identify the type of organic matter, variation in input and possible relationship with general temperature changes over the past decades. The concentrations ranged from 0.91 to 13.99 μg g?1 (dry weight) of total sterols, 0.20–2.14 μg g?1 of total n-alkanols and 0.13–2.38 μg g?1 of phytol. Cholest-5-en-3β-ol was the most abundant sterol. The fecal sterols, 5β-cholestan-3β-ol and 5β-cholestan-3α-ol, occurred at low concentration (<0.01–0.15 μg g?1), below the baseline values for this region. The lower carbon chain n-alkanols were more abundant, which suggested that algae, bacteria and zooplankton were the primary sources of the sedimentary organic matter. Phytol exhibited little variation across all of the cores, which appears to be the result of degradation. Variation in the concentration of compounds in one core was compared with the variation in mean air temperature (MAT) over time; this preliminary association showed a tendency toward increased concentration during the period in which the MAT was more elevated.  相似文献   

20.
Tungsten coil atomic emission spectrometry (WCAES) is used to determine trace levels of Mn (403.1 nm) and Cr (425.5 nm) in cow placenta. All samples were collected in Ilha Solteira, SP, Brazil. The instrumental setup is based on a tungsten filament extracted from 150 W, 15 V microscope light bulbs, a solid state power supply, fused silica lens, crossed Czerny-Turner spectrograph, and a thermoelectrically cooled charge-coupled device detector. The limits of detection (LOD) and quantification (LOQ) for Cr are 2 and 8 μg L?1, and 20 and 60 μg L?1 for Mn, respectively. Recoveries for 0.30 mg L?1 spikes of each analyte were in the range 93.0–103.0%, and relative standard deviation (RSD) was between 6.50 and 7.20% for both elements. Placenta samples were microwave-assisted digested with diluted HNO3 and H2O2 and analyzed by WCAES. The results for Cr and Mn were compared with values obtained by tandem inductively coupled plasma mass spectrometry (ICP-MS/MS). No statistically significant difference was observed between the different methods by applying a paired t test at a 95% confidence level. The average concentrations of Cr and Mn in the placentas evaluated were 0.95 ± 0.22 and 2.64 ± 0.39 μg g?1, respectively. By using a short integration time, LODs for Cr and Mn were lower than values reported by recent works using a similar WCAES system.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号