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151.
152.
Sequential extraction of heavy metals during composting of sewage sludge 总被引:15,自引:0,他引:15
The major limitation of soil application of sewage sludge compost is the total heavy metal contents and their bioavailability to the soil-plant system. This study was conducted to determine the heavy metal speciation and the influence of changing the physico-chemical properties of the medium in the course of composting on the concentrations, bioavailability or chemical forms of Cu, Zn, Pb and Ni in sewage sludge. Principal physical and chemical properties and FTIR spectroscopical characterization of sludge compost during treatment show the stability and maturity of end product. The total metal contents in the final compost were much lower than the limit values of composts to be used as good soil fertilizer. Furthermore, it was observed by using a sequential extraction procedure in sludge compost at different steps of treatment, that a large proportion of the heavy metals were associated to the residual fraction (70-80%) and more resistant fractions to extraction X-NaOH, X-EDTA, X-HNO3 (12-29%). Less than 2% of metals bound to bioavailable fractions X-(KNO3+H2O). Heavy metal distribution and bioavailability show some changes during composting depending on the metal itself and the physico-chemical properties of the medium. Bioavailable fractions of all elements tend to decrease except Ni-H2O. Zn and mainly Cu present more affinity to organic and carbonate fractions. In contrast, Pb is usually preferentially bound to sulfide forms X-HNO3. Nickel shows a significant decrease of organic form. Significant degrees of correlation were found between heavy metal fractions and changes of some selected variables (e.g. pH, ash, organic matter, humic substance) during the course of composting. Mobile fractions of metals are poorly predictable from the total content. The R2 value was significantly increased by the inclusion of other variables such as the amount of organic matter (OM) and pH. 相似文献
153.
Nonribosomal peptides and polyketides represent a large class of natural products that show an extreme structural diversity and broad pharmacological relevance. They are synthesized from simple building blocks such as amino or carboxy acids and malonate derivatives on multimodular enzymes called nonribosomal peptide synthetases (NRPSs) and polyketide synthases (PKSs), respectively. Although utilizing different substrates, NRPSs and PKSs show striking similarities in the modular architecture of their catalytic domains and product assembly-line mechanism. Among these compounds are well known antibiotics (penicillin, vancomycin and erythromycin) as well as potent immunosuppressive agents (cyclosporin, rapamycin and FK 506). This review focuses on the modular organization of NRPSs, PKSs and mixed NRPS/PKS systems and how modules and domains that build up the biosynthetic templates can be exploited for the rational design of recombinant enzymes capable of synthesizing novel compounds. 相似文献
154.
Jalaldeen Mohamed Harris Periyathamby Vinobab Ranil Kavindra Asela Kularatne Champika Ellawala Kankanamge 《环境科学学报(英文版)》2016,28(9):211-218
The necessity to understand the relationship between cyanobacterial species abundance and water quality variations in coastal lagoons is crucial to develop strategies to prevent further cyanobacterial proliferation. This paper evaluates the relationship between water quality variations on the distribution of cyanobacteria during a 12-month period in Batticaloa Lagoon (Sri Lanka) using Redundancy analysis and Pearson correlations. Drastic variations in pH, temperature, salinity, dissolved oxygen (DO) and total phosphorus (TP) levels were reported, but not turbidity and NO3−. This brackish waterbody is hypereutrophic (TP levels > 0.1 mg/L). The cyanobacterial community contained 13 genera and 22 species. NO3−, TP and turbidity levels positively influenced cyanobacterial abundance during all seasons indicating that nutrient (largely phosphorus) and sediment entry control is highly crucial along with periodic monitoring of cyanobacterial growth. 相似文献
155.
156.
Sall Mohamed Lamine Diaw Abdou Karim Diagne Gningue-Sall Diariatou Chevillot-Biraud Alexandre Oturan Nihal Oturan Mehmet Ali Aaron Jean-Jacques 《Environmental science and pollution research international》2017,24(26):21111-21127
Environmental Science and Pollution Research - Polypyrrole (PPy) conducting films, doped with 4-amino-3-hydroxynaphthalene sulfonic acid (AHNSA), were electrosynthesized by anodic oxidation of... 相似文献
157.
Maan Hayyan Mohd Ali Hashim Mohammed A. Al-Saadi Adeeb Hayyan Inas M. AlNashef Mohamed E.S. Mirghani 《Chemosphere》2013
In this work, the cytotoxicity and toxicity of phosphonium-based deep eutectic solvents (DESs) with three hydrogen bond donors, namely glycerine, ethylene glycol, and triethylene glycol were investigated. The cytotoxicity effect was tested using brine shrimp (Artemia salina). The toxicity was investigated using the two Gram positive bacteria Bacillus subtilis and Staphylococcus aureus, and two Gram negative bacteria Escherichia coli and Pseudomonas aeruginosa. The cytotoxicity of tested DESs was much higher than that of their individual components, indicating their toxicological behavior was different. It was also found that there was toxic effect on the studied bacteria, indicating their potential application as anti-bacterial agents. To the best of our knowledge, this is the first time the cytotoxicity and toxicity of phosphonium-based DESs were studied. 相似文献
158.
159.
Climatic drivers of potential hazards in Mediterranean coasts 总被引:1,自引:1,他引:0
Agustín Sánchez-Arcilla Cesar Mösso Joan Pau Sierra Marc Mestres Ali Harzallah Mohamed Senouci Mohamed El Raey 《Regional Environmental Change》2011,11(3):617-636
This paper studies climatic drivers (air and water temperature, precipitation rates, river discharge, sea level and storm
patterns) in four Mediterranean regions: the Catalan-Valencia Coast (Spain), the Oran (Algeria) and Gabès (Tunisia) Gulfs
and the western Nile Delta (Egypt). The paper also considers the potential hazards that these drivers can induce. It first
analyses climatic trends in the drivers, taking into account the available time series of recorded and simulated meteo-oceanographic
data from different sources. Next, it presents the general framework to assess biogeophysical hazards (flooding, erosion,
droughts and water quality), followed by a simple and yet robust evaluation of those hazards for the four studied coastal
sites. Assuming climate change projections under different scenarios and considering the observed trends in drivers, the resulting
erosion rates due to sea-level rise and wave storm effects have been estimated. The Nile and Ebro Deltas, together with the
Oran Gulf, are more vulnerable than the Gulfs of Valencia and Gabès. Regarding water quality in terms of (a) precipitation
and dissolved oxygen in the water column and (b) sea surface temperature, the results show that the most vulnerable zones
for the projected conditions (a) are the Gulfs of Oran, Valencia and Gabès, while the Nile Delta is the region where the decrease
in water quality will be less pronounced. For the projected conditions (b), the most vulnerable zone is the Ebro Delta, while
the impact in the other three cases will be smaller and of comparable magnitude. Finally, the overall future impact of these
hazards (associated to climatic change) in the four sites is discussed in comparative terms, deriving some conclusions. 相似文献
160.
HydroShare: Sharing Diverse Environmental Data Types and Models as Social Objects with Application to the Hydrology Domain 下载免费PDF全文