Characterization of fulvic acids during olive mill waste composting (Elemental,Thermal and fluorescence analyses)

Elemental analysis, fluorescence spectroscopy and differential scanning calorimetry (DSC) were applied to the study of fulvic acids isolated from different stages during olive mill waste composting. The fulvic extracted acids are characterized by a high nitrogen content and O/C ratio values that may result from the high degree of humification and the synthesis of more condensed humic complexes. This was confirmed by fluorescence spectroscopy in the synchronous-scan mode by the decrease of shoulder intensities at intermediate wavelengths indicating the increase of polycondensation and conjugation of unsaturated structures and the greater uniformity of fluorophores. Fluorescence spectra in the emission, excitation and synchronous modes became simpler with compost maturation. This was confirmed by DSC results which proved the high degree of polycondensation of aromatic nuclei of fulvic acid molecules during olive mill waste composting.     

Characterization of fulvic acids during olive mill waste composting (Elemental, Thermal and fluorescence analyses)

Elemental analysis, fluorescence spectroscopy and differential scanning calorimetry (DSC) were applied to the study of fulvic acids isolated from different stages during olive mill waste composting. The fulvic extracted acids are characterized by a high nitrogen content and O/C ratio values that may result from the high degree of humification and the synthesis of more condensed humic complexes. This was confirmed by fluorescence spectroscopy in the synchronous-scan mode by the decrease of shoulder intensities at intermediate wavelengths indicating the increase of polycondensation and conjugation of unsaturated structures and the greater uniformity of fluorophores. Fluorescence spectra in the emission, excitation and synchronous modes became simpler with compost maturation. This was confirmed by DSC results which proved the high degree of polycondensation of aromatic nuclei of fulvic acid molecules during olive mill waste composting.     

Sequential extraction of heavy metals during composting of sewage sludge

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.     

Restoration of foothills rough fescue grassland following pipeline disturbance in southwestern Alberta

The effects of pipeline construction and reclamation techniques on the restoration of rough fescue plant communities following pipeline construction in southwestern Alberta, Canada were evaluated after 7–40 years. The pipeline construction right-of-way (ROW) sites varied from no recovery of rough fescue grassland to moderate recovery. The ROW sites had a higher proportion of introduced grasses and forbs, less topsoil, and poorer rangeland health than the adjacent undisturbed grassland. Within the ROW sites, less topsoil was present on those with larger diameter pipe and which had topsoil fully stripped from the ROW during construction. Introduced grasses, Festuca ovina (sheep fescue) and Poa compressa (Canada bluegrass), succeeded in establishment following seeding and persisted for at least 40 years. Poa pratensis (Kentucky bluegrass) dominated many of the ROW sites. Contributing factors to moderate recovery of rough fescue grassland were related to post-growing season pipeline construction, ideally, between August and March, summer or fall seeding, and minimum disturbance trench-only stripping. Reclamation practices appeared more important than time since restoration in the restoration of rough fescue grassland.     

21,000 Years of Ethiopian African monsoon variability recorded in sediments of the western Nile deep-sea fan

The Nile delta sedimentation constitutes a continuous high-resolution record of Ethiopian African monsoon (EAM) regime intensity. Multi-proxy analyses performed on hemipelagic sediments deposited on the Nile deep-sea fan allow the quantification of the Saharan aeolian dust and the Blue/White Nile River suspended matter frequency fluctuations during the last 21,000 years. The radiogenic strontium and neodymium isotopes, clay mineralogy, elemental composition and preliminary palynological analyses reveal large changes in source components, oscillating between a dominant aeolian Saharan contribution during the Last Glacial Maximum (LGM) and the late Holocene (~4,000–2,000 years), a dominant Blue/Atbara Nile River contribution during the early Holocene (15,000–8,000 years) and a probable White Nile River contribution during the middle Holocene (8,000–4,000 years). The following main features are highlighted: (1) The rapid shift from the LGM arid conditions to the African Humid Period (AHP) started at about 15,000 years. The AHP extends until 8,000 years, and we suggest that the EAM maximum between 15,000 and 8,000 years is responsible for a larger Blue/Atbara Nile sediment load and freshwater input into the eastern Mediterranean Sea. (2) The transition between the AHP and the arid late Holocene is gradual and occurs in two main phases between 8,400–6,500 years and 6,500–3,200 years. We suggest that the main rain belt shifted southward from 8,000 to ~4,000 years and was responsible for progressively reduced sediment load and freshwater input into the eastern Mediterranean Sea. (3) The aridification along the Nile catchments occurred from ~4,000 to 2,000 years. This dry period, which culminates at 3,200 year, seems to coincide with a re-establishment of increased oceanic primary productivity in the western Mediterranean Sea. Such a pattern imposes a large and rapid northward shift of the rain belt over the Ethiopian highlands (5–15°N) since 15,000 years. Precipitation over Ethiopia increased from 15,000 to 8,000 years. It was followed by a gradual southward shift of the rain belt over the equator from 8,000 to 4,000 years and finally a large shift of the rain belt south the equator between 4,000 and 2,000 years inducing North African aridification. We postulate that the decrease in thermohaline water Mediterranean circulation could be part of a response to huge volumes of freshwater delivered principally by the Nile River from 15,000 to 8,000 years in the eastern Mediterranean.     

Magnetic resonance imaging of the fetus: A study of 20 cases performed without curarization

Twenty patients underwent magnetic resonance imaging (MRI) at a mean gestational age of 32 weeks. There were 12 patients with suspected fetal brain abnormality and four with intrauterine growth retardation (IUGR), while the remaining four cases were studied for other reasons. The MRI examinations were performed on a 0.5 Tesla machine, with surface coils. One minute acquisition time T1 sequences were used. All the studies were performed without fetal curarization, and only under maternal sedation using flunitrazepam given per os 1 h before MRI examination. Three examinations were incomplete because of fetal movement artefacts. In the remaining cases, MRI allowed the examination of fetal brain anatomy. In five cases, it helped to differentiate isolated hydrocephalus and corpus callosum agenesis. Sub-ependymal nodules were depicted in a case of fetal tuberous sclerosis. One suspected arachnoid cyst was proved to be an ultrasound artefact. Decreased fetal fat on MR images was correlated with low birth weight in cases of IUGR. Due to its better spatial resolution, ultrasonography was more accurate for the diagnosis of facial and lumbar anomalies. Fetal MRI may be performed without curarization. Surface coils allow the detailed analysis of brain parenchyma, and thus MRI is especially useful in the difficult prenatal diagnosis of fetal brain abnormalities.     

Fate of polycyclic aromatic hydrocarbons during composting of lagooning sewage sludge

The fate of 16 polycyclic aromatic hydrocarbons (PAHs), targeted by the USEPA agency, has been investigated during composting of lagooning sludge. Composting shows efficient decrease of the content and the bioavailability of each PAH. Biodegradation and sorption are suggested as the main mechanisms contributing to this decrease. During the stabilization phase of composting, extensive microbial degradation of PAHs, mainly those with a low number of aromatic rings, was achieved following development of intense thermophilic communities. However, partial sorption of PAH to non-accessible sites temporarily limits the mobility mainly of PAHs with a high number of aromatic rings plus acenaphthene and acenaphthylene, and allows them to escape microbial attack. During the maturation phase, the development of a mesophilic population could play an important role in the degradation of the remaining PAH. During this phase of composting, PAH sequestration and binding of their oxidative metabolites within new-formed humic substances might also explain PAH decrease at the end of composting. The tendency of change of content or bioavailability of various PAH compounds during composting is found to be strongly related to the number of their aromatic rings, their molecular weight and structure.     

Altruism during predation in an assassin bug

Zelus annulosus is an assassin bug species mostly noted on Hirtella physophora, a myrmecophyte specifically associated with the ant Allomerus decemarticulatus known to build traps on host tree twigs to ambush insect preys. The Z. annulosus females lay egg clutches protected by a sticky substance. To avoid being trapped, the first three instars of nymphs remain grouped in a clutch beneath the leaves on which they hatched, yet from time to time, they climb onto the upper side to group ambush preys. Long-distance prey detection permits these bugs to capture flying or jumping insects that alight on their leaves. Like some other Zelus species, the sticky substance of the sundew setae on their forelegs aids in prey capture. Group ambushing permits early instars to capture insects that they then share or not depending on prey size and the hunger of the successful nymphs. Fourth and fifth instars, with greater needs, rather ambush solitarily on different host tree leaves, but attract siblings to share large preys. Communal feeding permits faster prey consumption, enabling small nymphs to return sooner to the shelter of their leaves. By improving the regularity of feeding for each nymph, it likely regulates nymphal development, synchronizing molting and subsequently limiting cannibalism.     

Dioxins in adipose tissue of non-occupationally exposed persons in France: correlation with individual food exposure

We evaluated individual adipose tissue (subcutaneous lipomas) dioxin contamination in non-occupationally exposed persons living in France (adult patients undergoing a surgical ablation of benign lipomas), in relation to the corresponding individually evaluated mean daily dietary dioxin intake (DDDI). The diet survey (questionnaire) included information on consumption of meat, fish, milk and dairy products, from which the individual DDDI was calculated. Sixteen subjects participated in this study. DDDI ranged between 1.06 and 3.31 pg I-TEQ/kg body weight, bw (mean value: 2.05+/-0.72). Adipose tissue polychlorinated dibenzo-p-dioxins (PCDD)/polychlorinated dibenzofurans (PCDF) levels ranged between 18.5 and 76.9 pg I-TEQ/g lipids (mean value: 35.6+/-14.8). No relation was found between the DDDI and adipose tissue PCDD/PCDF concentrations. The mean DDDI in France does not fundamentally differ from those found in other industrialised countries, is within the range of 1-4 pg I-TEQ/kg/day recently suggested by WHO-ECEH/ICPS for the tolerable daily intake of dioxins. Adipose tissue PCDD/PCDFs levels are similar to levels in other European countries and USA without relation to sex or age, and can be considered representative European background concentrations. Globalisation of alimentary production leads to a similar food exposure in Western European countries, in spite of dioxins accidental selective contaminations that are epiphenomenon and thus do not have any impact in human dioxin background levels.     

Comparative study of humic acids of the mound of a wood-feeding termite and of the litter directly below in the Amazon river delta

In order to determine the role of termites in the recycling of organic matter and in humification processes, organic matter from the mound of a wood-feeding termite (Nasutitermes sp.) and from the litter directly below has been studied in secondary forest on the campus of Belem University, in Brazil. The carbon content was slightly lower in the litter (just beneath the mound) than in the mound, but nitrogen was much more abundant in the mound. As a consequence, the C/N ratio of fragmented litter total organic matter is very high, which shows that the humification process is not complete. Therefore, plant debris seemed to be more degraded in the mound than in the litter, indicating a humification gradient from mound to litter. Humic acid extracted from the mound and from the litter was compared by using elemental, E4/E6 ratio, spectroscopic (FTIR) analyses, and Sephadex gel chromatography. First, humic acids were more abundant in the mound than in the litter, showing that humification processes were more advanced in the mound than in the litter. Gel-permeation chromatography showed that the humic acids of the mound contained more low-molecular-weight fractions than those of the litter. In addition, the results of infrared spectra, E4/E6 ratio and elemental composition can confirm the fulvic character of mound material and the humic character of litter material. Therefore, the plant debris seems to follow two different humification pathways in the two environments, as long as the mound is alive.