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A field experiment was conducted to evaluate the efficiency of native monocotyledonous weed species for heavy metal phytoextraction from municipal solid waste (MSW) compost. Results showed that total contents of cadium (Cd), copper (Cu), and zinc (Zn) in MSW compost generally exceeded the maximum levels indicated in Chinese regulations, except nickel (Ni). The general trend of metal accumulation in plants was Zn>Cu>Ni>Cd and accumulation differences depended on plant species. Except for Carex tristachya, the Cd, Cu, and Ni contents in above-ground parts of four other species were within the normal values in plants. Most plants accumulated target metals mostly in the roots. With BCF and TF values >1, Carex tristachya displayed some Cd-hyperaccumulative characteristics, being classified as potential species for phytoextraction of Cd from MSW compost. Other species can be considered adequate candidates for metal stabilization and soil conservation.
Understanding the salt resistance mechanism of wild soybean is important in improving salt tolerance of cultivated soybean. Therefore, we comparatively analyzed effects of NaCl on photosynthesis, antioxidant enzyme activity, and ion distribution in a cultivated (Glycine. max) and a wild (Glycine soja) soybean to study the salt resistance mechanism of the G. soja. The results showed that more Na⁺ was accumulated in the G. soja roots than in the G. max roots, but the Na⁺ in the G. soja leaves was much less than that observed in the G. max leaves. The Na⁺ concentrations in the G. soja leaves were not high enough to affect the photosynthetic apparatus, which was demonstrated by less inhibition of photosynthetic activity, stomatal conductance, carboxylation efficiency in the G. soja leaves than in the G. max leaves after treated with different concentrations of NaCl. Meanwhile, there were no significant changes in intercellular CO₂ concentration, maximum PSII quantum yield, and relative water content in the G. soja leaves after NaCl treatment, while they significantly decreased in the G. max leaves. The nonphotochemical quenching and the activities of superoxide dismutase (EC 1.15.1.1) and ascorbate peroxidase (EC 1.11.1.11) in the G. soja leaves increased with the increasing of NaCl concentrations, whereas only the activity of superoxide dismutase increased in G. max leaves. Based on these results, we suggested that the G. soja is able to accumulate higher levels of Na⁺ in its roots, and prevent the transportation of Na⁺ to leaves to protect photosynthetic apparatus from salt damage.
Particle size fractions, varying from 1.6 to 0.1 mm, were separated from samples of municipal solid waste (MSW) compost. Several physical and chemical parameters of the samples with different particle sizes were measured. The results indicated particle size fractionation changed the physical properties and chemical component distribution of compost. Bulk density of the compost increased as particle size decreased. However, with the decrease of particle size there is a trend to decrease some soil parameters as pH, porosity, saturated water holding capacity, organic content, and Ca, Fe, Mg, and Mn contents. Higher organic content was found in fractions of diameter exceeding 0.4 mm, and total N content was higher (P<0.05) in fractions of diameter exceeding 0.8 mm than <0.8 mm fractions. Phosphorus was mainly distributed in coarse fractions larger than 0.8 mm, but K was concentrated in fine fractions of <0.8 mm. Calcium, Fe, Mg, and Mn contents in fractions >0.8 mm were higher (P<0.05) than those in fractions < 0.4 mm and control. Heavy metal concentrations in individual particles have strong particle size dependence. Lead was largely contained in fractions <0.8 mm, 244% higher than in >0.8 mm fractions. High Cu content was observed in the size range of 0.2-0.4 mm and 0.8-0.4 mm, with the maximum of 1,317 mg·kg⁻¹ in the range of 0.8-0.4 mm. Zinc concentration was found to be the lowest in the range of 1.6-0.8 mm as compared to other fractions and control. No significant differences in Cd content were found between each treatment and control. Chromium and Ni were associated with the <0.8 mm particles more than any other fractions, and their concentrations were 177% and 140% higher than other particle sizes obtained, respectively. Based on the physical and chemical properties of different compost fractions used in this experiment, it is observed that coarse compost particles larger than 0.8 mm have considerable potential in agricultural applications as soil amendments.
Study of the radial growth response to climate factors at different tree ages is essential for predicting forest dynamics and formulating correct management policies. In this study, we analysed the growth responsiveness of Picea crassifolia to climate conditions, and evaluated its relationship to tree age at the individual tree scale, in the transitional zone between regions affected by the East Asian monsoon and winds blowing from the west (westerlies) in the Qilian Mountains. On three study sites, 150 cores were taken from 75 trees. Pearson correlation coefficients were calculated between the standardized tree-ring series of each core (and chronology) and climatic factors which were utilized to research the climate-growth relationships. Quadratic polynomial fitting was used to test the relationships between tree age, chronological parameters, and the radial growth response to climate. Radial growth was positively influenced by total precipitation for the previous July-September and the current May-July. Additionally, radial growth was negatively correlated with the total monthly precipitation for the current September, and the mean monthly temperature for the previous July. Trees younger than 80 years old showed a stronger response to accumulative precipitation in the previous July-September, those older than 160 years old showed a stronger response to precipitation at the end of current growing season, while those of 140–160 years old showed a weaker response to precipitation in the current May-July.
Today, constructing well-facilitated capital farmland on a large scale is one of the key strategic initiatives for enhancing the national capacity for food security. In order to strengthen the scientific and rational distribution of well-facilitated capital farmland, this article, starting with the discussion of ecosystem integrity of regional well-facilitated capital farmland on the basis of ecological niche theory, proposes the concept of ecological niche for well-facilitated capital farmland, and constructs “ecostate” and “ecorole” evaluation models (Nᵢ model) of ecological niche for well-facilitated capital farmland. This is verified by studying the case of the city of Xinzheng, Henan Province, China. As the research result shows, first the condition of farmland in Xinzheng is generally good, and the farmland in the whole city is suitable for the construction of well-facilitated capital farmland covering 34,224.48 hm², 63.18% of the total area, which is mainly distributed in the southern and northwestern parts of the city. Second, the evaluation results are generally in consistency with the actual situation, which indicates that the Nᵢ model is scientific and realistic in the evaluation of suitability for constructing well-facilitated capital farmland. Meanwhile, the Nᵢ values are helpful for indicating the suitability for regional well-facilitated capital farmland. Third, using the most suitable ecological niche to explain standards of construction for well-facilitated capital farmland, and matching n dimension resources ecological niche along with most suitable ecological niche to evaluate well-facilitated capital farmland will convey clear ecological significance and be quite helpful to develop plans and measures for constructing well-facilitated capital farmland based on the size and changes of niche-fitness values.
Multidrug-resistant Acinetobacter baumannii is an important bacterium causing nosocomial infections; A. baumannii infections have increased in our hospital since 2009. However, multidrug-resistant A. baumannii, which was mainly isolated from patients in each intensive care unit (ICU), rapidly increased from December 2012 to January 2013. Therefore, we described the molecular characteristics of A. baumannii by pulsed-field gel electrophoresis (PFGE). We also detected resistance genes for β-lactam, aminoglycosides, and plasmid-mediated quinolones. Disinfectant-resistant genes were also detected in the clinical isolates of blaOXA-51-positive multidrug-resistant A. baumannii. The conjugative test was performed to detect whether or not resistance genes can be transferred to different strains. Carbonyl cyanide m-chlorophenylhydrazone (CCCP) inhibition test was conducted to analyze the factors influencing the resistance of A. baumannii to imipenem, meropenem, ceftazidime, levofloxacin, and tigecycline. PFGE profiles contained 12 strains, including 20 type C strains (47.6%), 4 type D strains (9.5%), and 1 to 3 strains of other types; 38 strains were distributed in patients in each ICU. In our test samples, the presence of blaOXA-23 was closely related to carbapenem resistance. The 16S rRNA methylase gene armA was associated with resistance to amikacin, gentamicin, and tobramycin. The multidrug-resistant A. baumannii was closely related to various resistance genes. These results indicated that multidrug-resistant A. baumannii with type C strains was predominant in our hospital in this period.
Rapid industrialization and urbanization have presented a dilemma to traditional environmental policies, and severe haze pollution has attracted particular attention in China. This paper employed the exploratory spatial data analysis technique to analyze global and local spatial auto-correlation of environmental regulations (ERS) and haze pollution. Static and dynamic spatial panel data models were further established to investigate the influence of ERS and its spatial spillover effect on haze pollution across 31 provinces of China in 2005-2015. Results showed that significant spatial autocorrelation existed for both ERS and haze pollution in China, forming different aggregation regions in terms of geographical distribution. There was strong evidence for the “inverted-U”-shaped EKC relationship between ERS and haze pollution regardless of whether it was the static or dynamic spatial econometric model. In addition, haze pollution was not only affected by economic growth, population size, and urbanization, but also by the haze pollution in the previous period. Conclusions and control strategies that would be of great significance for implementing effective management measures were synoptically discussed.
Populus euphratica Oliv., a species of the model woody plant genus Populus, is well known for its tolerance to salinity stress, the underlying mechanism of which is a research hotspot. Transient expression of fluorescent fusion proteins is commonly used for rapid assessment of gene functions and interactions, and thus would be useful to study the genes involved in salt tolerance in this species. Our transient gene expression protocol for P. euphratica included a simple protoplast preparation and transformation procedure from suspension cultured cells. The highest protoplast yield (8 9 107 g-1 fresh weight) with high viability (above 90 %) was obtained using an optimized enzyme mix of 4 % (w/v) cellulase R10, 0.5 % (w/v) pectinase, and 0.2 % (w/v) hemicellulase. Factors affecting protoplast transformation efficiency were also optimized: 20 lg plasmid DNA versus 105 protoplasts, and a transformation time of 20 min using PEG, which resulted in a transformation efficiency greater than 50 %. A pair of known markers was simultaneously and correctly expressed in the same P. euphratica protoplasts by co-transformation. The isolation and transformation protocol took 5 h, and results could be obtained within 24 h. This protoplast transient expression system is suitable for studying gene expression, protein localization, and protein–protein interactions in woody plants. In addition, it would be particularly useful for studying the signaling pathway involved in the salt tolerance of P. euphratica in a homologous system, which may not even be possible using protoplasts prepared from other species.
Plant community assembly is determined by species turnover and intraspecific trait variations (ITV) controlled by environment changes. However, little is known about how species turnover and ITV affect the responses of plant community to habitat changes and grazing disturbance in semiarid grasslands. Here, we measured five functional plant traits in four typical grassland habitats under fencing and grazing disturbance in a semiarid grassland, Northern China, including plant height, specific leaf area (SLA), leaf dry matter content (LDMC), leaf nitrogen content (LNC) and leaf carbon: nitrogen ratio (C:N). We also calculated the community weighted means (CWM) and non-weighted means (CM) of all traits and examined the relative roles of species turnover and ITV in affecting the responses of community traits to habitat changes and grazing disturbance. Our results showed that the CWM and CM values of five functional traits differed with grassland habitat changes. As compared to other grasslands, the Stipa steppe had the higher plant height, the sandy grassland had the higher SLA and lower LDMC, and the meadow had the lower LNC and higher C:N. Grazing decreased plant height across grassland habitats, as well as decreased SLA and increased LDMC in meadow. The responses of all community-level traits to habitat changes were driven by species turnover, while the responses of phenotypic traits (height, SLA and LDMC) to grazing were determined by both species turnover and ITV. So, we argue that ITV should be considered when understanding plant community assembly under grazing disturbance regime in semiarid grasslands.
Linking the response of tree growth to global warming is a key to fully appreciating the impact of climate change on forests. To examine the impacts of temperature and precipitation on tree growth, we studied the radial growth of Pinus tabulaeformis along an altitude gradient from 2032 m a.s.l. to 2361 m a.s.l. on the Helan Mountains, which is almost the northwestern limit of P. tabulaeformis distribution in China. The results showed that, radial growth of P. tabulaeformis decreased significantly (P <0.05) at the low altitude (2032 m a.s.l.) and remained almost steady at the middle and high altitude (2200 m a.s.l. and 2361 m a.s.l.) during the past decades, which was attributed to different climate-radial growth relationships at different altitudes. Total precipitation from the previous July to the current June was an important and effective climatic factor for radial growth at all altitudes. Radial growth was negatively correlated with the mean temperature of the current March at the low altitude and was positively and negatively correlated with the mean temperature of the previous October and the current July at the high altitude, respectively. Increasing temperature of the March under the context of global warming was the main reason for growth reduction at the low altitude. Radial growth at the middle and high altitudes didn't suffer from global warming. It was inferred that conifers at low altitudes of the species' dry distribution limit were more vulnerable to global warming. To cope with possible intensified drought in the growing season and growth reduction in the future, thinning and afforestation should be carried out in the forests, especially at low altitudes.
The environmental challenge of crude oil-contaminated soil is difficult to address due to its complicated components and the mechanism of material transformation. In order to study the bioremediation of soil contaminated by crude oil, we designed five simulation test systems: a sterilization system, an oxygenated and water-controlled system, a nitrogen (N)/phosphorus (P) adjusted system, a broth-added system, and a double-broth-added system. The results show that the highest removal of crude oil from soil was increased to 34.23% by regulating the micro-ecological environment after 91 days in a simulation system. Regulating N and P can effectively strengthen the mineralization action of microorganisms on crude oil. Biodegradation had the most effect on the removal of oil, accounting for more than 58% of the total removal. Moreover, mineralization was dominant in biodegradation. Degradation of crude oil components was alkanes-based, accounting for 50 to 80% of total oil removal. By regulating moisture, temperature, oxygen content, N/P levels, and enrichment broth, the half-life of crude oil in a simulation system can be shortened to 182 days.
In this study, we investigated responses of the mid-successional species Acer truncatum Bunge and the late-successional species Quercus variabilis Blume to three solar illumination conditions: (1) constant low light (CL), (2) constant high light (CH) and (3) low light first and high light afterwards (LH). The last treatment was to simulate a canopy opening. Both species exhibited increases in biomass, totally and in part, and decreases in leaf water content, specific leaf area and chlorophyll concentrations in LH treatment compared to CL treatment. For A. truncatum, exposure to high light condition (LH) increased crown area, and decreased root to shoot ratio, stem mass ratio and leaf perimeter. However, for Q. variabilis, LH treatment increased stem diameter at ground height, effective quantum yield, photochemical quenching and decreased maximum photosystem II quantum yield. The biomass allocation pattern did not change in Q. variabilis among three light conditions. With respect to newly developed leaves, no significant differences were found in leaf size of Q. variabilis between LH treatment and CH treatment while that of A. truncatum decreased in LH treatment. All chlorophyll fluorescence parameters in newly developed oak leaves in LH treatment increased compared to those of CH treatment while no difference was found for A. truncatum between LH and CH treatment. A. truncatum displayed a greater overall plasticity than Q. variabilis although the oak seedlings have a greater plasticity with respect to chlorophyll concentration and chlorophyll fluorescence parameters. A. truncatum should be a better candidate for vegetation recovery, especially in places with heterogeneous light conditions.
There is large area of saline abandoned and lowyielding land distributed in coastal zone in the world. Soil salinity which inhibits plant growth and decreases crop yield is a serious and chronic problem for agricultural production. Improving plant salt tolerance is a feasible way to solve this problem. Plant physiological and biochemical responses under salinity stress become a hot issue at present, because it can provide insights into how plants may be modified to become more tolerant. It is generally known that the negative effects of soil salinity on plants are ascribed to ion toxicity, oxidative stress and osmotic stress, and great progress has been made in the study on molecular and physiological mechanisms of plant salinity tolerance in recent years. However, the present knowledge is not easily applied in the agronomy research under field environment. In this review, we simplified the physiological adaptive mechanisms in plants grown in saline soil and put forward a practical procedure for discerning physiological status and responses. In our opinion, this procedure consists of two steps. First, negative effects of salt stress are evaluated by the changes in biomass, crop yield and photosynthesis. Second, the underlying reasons are analyzed from osmotic regulation, antioxidant response and ion homeostasis. Photosynthesis is a good indicator of the harmful effects of saline soil on plants because of its close relation with crop yield and high sensitivity to environmental stress. Particularly, chlorophyll a fluorescence transient has been accepted as a reliable, sensitive and convenient tool in photosynthesis research in recent years, and it can facilitate and enrich photosynthetic research under field environment.
Six kinds of municipal sludge samples were collected from wastewater treatment plants (WWTPs) from Guangzhou in southern China. Total concentration of Cu, Pb, Zn, Cr, Ni, Cd, and Mn in the sludge was determined, and used obtained values to appraise the degree of agricultural land pollution on the base of four pollution indixes. Results showed that the concentrations of the heavy metals Cu (4.567 mg/kg), Mn (1.844 mg/kg), Ni (148 mg/kg), Cr (121 mg/kg), and Cd (5.99 mg/kg) in S1 sludge were higher than that of the other sludges. In six sludge samples the concentrations of Mn, Zn, and Cu were highest, followed by Ni, Pb, and Cr. Cd had the lowest concentration. All were higher than those recorded in the background data for crop soils. With the exception of Cu and Cd from site S1, and Ni from sites S1, S2, and S5, all other metal concentrations conformed to permissible levels prescribed by the national application standard of acid soil in China (GB18918-2002). The geoaccumulation index (Igeo) assessment results indicate that there are serious risks in agricultural utilization for the existing Cu and Zn in these six kinds of sludges, especially the Igeo, which was 6.53 for Cu, 3.21 for Mn, 2.78 for Cd in the S1 sludge. The results of RI showed that sludge had high potential ecological risks, especially caused by Cd, which should give rise to widespread concerns. The potential ecological risk index (RI) of heavy metals in six sludge samples was ranked in the order of S1>S2>S4>S3>S5>S6.
2,3,5,4'-tetrahydroxy stilbene-2-O-ß-D-glucoside (THSG) exerts multiple pharmacodynamic actions, found in Fallopia multiflora, but the biosynthesis pathway of THSG is still unclear. To clear this ambiguity, we constructed suppression subtractive hybridization (SSH) libraries to screen the genes involved in THSG biosynthesis from two F. multiflora varieties, which vary significantly in THSG content. Twelve non-redundant differentially expressed sequence tags were obtained and the full lengths of 4 unreported fragments were amplified by rapid amplification of cDNA ends. We totally got 7 fulllength transcripts, and all of them were aligned to the transcriptome and digital gene expression tag profiling database of four F. multiflora tissues (root, stem and leaf from Deqing F. multiflora and another root from Chongqing F. multiflora; data unpublished) using local BLAST. The results showed that there was a significant, organ specific difference in the expression of fragments and full-length sequences. All the sequences were annotated by aligning to nucleotide and protein databases. Kyoto Encyclopedia of Genes and Genomes pathway analysis indicated that THSG biosynthesis was correlated with multiple life activities.
Coal gasification coarse cinder (CGCC) is the main waste in the coal gasification industry, containing low calorific value but high heavy metal residuals. To achieve environmental toxicity stabilization and waste recycling, we developed a manufacturing method of multiple-functional ceramsite from CGCC by pelletizing and sintering. By altering key parameters during the manufacturing process (including CGCC content, sintering temperature, and time), the physical properties and leaching toxicity of ceramsite were evaluated. Sintering temperature was identified with a significantly positive relationship with ceramsite’s compressive strength, whereas CGCC content was negatively correlated with water adsorption. The highest compressive strength (24.00 MPa) and relatively lower water absorption (21.36%) was achieved at 50% CGCC content and 1,150ºC sintering for 30 min. The toxicity tests showed acceptable leaching heavy metals with minimal environmental impact. Considering the energy conservation and the maximal recycling of CGCC, optimal ceramsite manufacturing is suggested as 50% CGCC content and 1,150ºC/10 min sintering temperature/time. Our results indicated that multiple-functional ceramsite manufacturing is a low-cost and environmentally friendly approach for CGCC recycling.
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