Organochlorine pesticides and polychlorinated biphenyl residues in reared and wild Dicentrarchus labrax from the Mediterranean Sea (Sicily, Italy)

The aim of this research was to compare the levels of organochlorine pesticides and PCBs in samples of Dicentrarchus labrax living in the Straits of Messina with samples cultivated in cages in the Mediterranean Sea. Muscles and liver tissues sampled over the months, within the same year, were analyzed. The quantitative determination of the organochlorine compounds was performed by GC-ECD and confirmed with GC–MS. The results showed that the concentrations of DDTs in muscles and livers as such of reared sea bass were in the range 0.2–1.3 μg/kg and 9.6 –48.4 μg/kg, respectively. In wild fish the concentrations of DDTs were very much lower: 0.1 μg/kg in muscles, 5.1–9.0 μg/kg in livers. Total PCBs levels were higher in cultivated sea bass than in wild fish; the concentration ranges were 5.3–59.7 μg/kg and 74.4–267.4 μg/kg in muscle and liver of reared samples, respectively, and 1.1–1.5 μg/kg and 63.2–109.4 μg/kg in muscle and liver of wild samples, respectively.     

Reconstruction of the environmental evolution of a Sicilian saltmarsh (Italy)

The present study deals with the reconstruction of the environmental evolution of a Trapani saltmarsh (southwestern Sicily, Italy) by combining different analytical approaches such as metal content evaluation, low-field nuclear magnetic resonance (NMR) relaxometry, and benthic foraminifera identification. A 41 cm core was collected in the sediments of a Trapani saltmarsh (southwestern Sicily, Italy) at a water depth of about 50 cm. Different time intervals were recognized, each characterized by peculiar features that testify different environmental conditions. In particular, the bottom layers of the sediment core (41–28 cm) comprised the lowest amount of mud fraction, only some selected metals, and the lowest foraminiferal density. Here, co-occurrence of abundant microcrystals of gypsum and Ammonia tepida is indicative of hyper-saline conditions. In the sediments from 28 to 6 cm, mud fraction and number of metal elements resulted higher due to the increase of the anthropogenic pressure. The sediments in the last time interval, corresponding to the environmental recovery of the saltmarsh, showed an increase of foraminiferal density, a decrease of the mud fraction, and a trend in the metal concentration attributable to the protection policy applied since 1990. NMR relaxometry parameters highlighted the changes of sediment chemical–physical heterogeneity going from the bottom to the top of the core. These heterogeneities have been related to the different intervals recognized as aforementioned. The present study highlights how the anthropogenic pressure modifies the environmental conditions of a transitional ecosystem like saltmarshes.     

Spectroscopic and conformational properties of size-fractions separated from a lignite humic acid

A lignite humic acid (HA) was fractionated by preparative high performance size-exclusion chromatography (HPSEC) in seven different size-fractions. The size-fractions were characterized by cross polarization (CP) magic angle spinning (MAS) (13)C NMR spectroscopy and a further analytical HPSEC elution under UV and fluorescence detection. The alkyl hydrophobic components mainly distributed in the largest molecular-size-fraction, whereas the amount of oxidized carbons increased with decreasing size of fractions. Cross polarization time (T(CH)) and proton spin-lattice relaxation time in the rotating frame (T(1rho)(H)) were measured from variable contact time (VCT) experiments. The bulk HA was characterized by the shortest T(CH) values and the longest T(1rho)(H) values which suggested, respectively, one. an aggregation of components in a large conformation that favored a fast H-C cross polarization, and, two. consequent steric hindrances that prevented fast local molecular motions and decreased proton relaxation rates. Conversely, the separated size-fractions showed longer T(CH) values and shorter T(1rho)(H) values than the bulk HA, thereby indicating that they were constituted by a larger number of mobile molecular conformations. The UV and fluorescence absorptions were both low in the large size-fractions that mainly contained alkyl carbons, whereas they increased in the olephinic- and aromatic-rich fractions with intermediate molecular-size, and decreased again in the smaller fractions which were predominantly composed by oxidized carbons. These results support the supramolecular structure of humic substances and indicate that the observed variation in conformational distribution in humic association may be used to explain environmental processes with additional precision.     

Antecedents,consequences, and moderators of time perspective heterogeneity for knowledge management in MNO teams

Multinational organizations (MNOs), more so than other organizations, are likely to require individuals with different perspectives, experiences, and backgrounds to form teams and collaboratively manage knowledge. We develop a framework that shows why variations in time perspectives among members of teams occur and how such differences can exert significant but unacknowledged influences on knowledge management efforts in MNOs, including: (1) innovativeness of knowledge created (2) speed of knowledge creation and (3) speed of knowledge transfer between teams. We also provide new insights into benefits of time perspective heterogeneity for teams managing knowledge. Copyright © 2007 John Wiley & Sons, Ltd.     

Polymerization of humic substances by an enzyme-catalyzed oxidative coupling

 A novel understanding of the structural features of humic substances supports the self-assembly supramolecular association of relatively small molecules rather than their polymeric nature. An increase in the conformational stability of humus may thus be achieved through promotion of intermolecular covalent bondings between heterogeneous humic molecules by an enzyme-catalyzed oxidative reaction. We present evidence from high performance size exclusion chromatography (HPSEC) and diffuse reflectance infrared spectrometry (DRIFT) that oxidation of a humic material catalyzed by horseradish peroxidase stabilizes the humic structure by the formation of aryl and alkyl ethers and permanently enhances its molecular size. Received: 15 May 2000 / Accepted in revised form: 14 July 2000     

Airborne concentrations of SARS-CoV-2 in indoor community environments in Italy

Environmental Science and Pollution Research - COVID-19 pandemic raised a debate regarding the role of airborne transmission. Information regarding virus-laden aerosol concentrations is still...     

Assessment of the in vivo genotoxicity of a new formulation of Bacillus thuringiensis var israelensis SH-14

Biological control agents have become a useful alternative for the reduction of the use of chemical insecticides. LABIOFAM (Cuba) is developing a new formulation of a biolarvicide that possesses as active biological agent Bacillus thuringiensis var israelensis serotype H14. In order to evaluate the genotoxicity of this new formulation, an in vivo battery test was used: micronucleus (MN), chromosome aberrations (CAs), and sperm morphology (SM) assays. A dose of 6.45?×?10⁸ spores was administered per animal via oral administration. Bone marrow cells were collected 24?h after a two day treatment for the MN assay, and 24?h after a unique treatment for the CA assay, using cyclophosphamide as the positive control. Sperm cells were collected at 5 weeks from the first of five administrations for the SM test, using acrylamide as positive control. Bacillus thuringiensis var israelensis serotype H14 failed to show either a significative increase of micronucleated polychromatic erythrocytes, chromosomal aberrations, or sperm abnormalities. Acute oral administration of a high dose of Bacillus thuringiensis var israelensis serotype H14 did not produce mutagenic effects in bone marrow or sperm cells.     

Increased retention of polycyclic aromatic hydrocarbons in soils induced by soil treatment with humic substances

The analytical recovery of a mixture of polycyclic aromatic hydrocarbons (PAHs) was determined from a soil before and after oxidation with hydrogen peroxide, and subsequently treated with increasing amounts of an exogenous humic acid and subjected to different incubation periods. The release of PAHs from soil depended on the specific structure and physico-chemical properties of each PAH, and increased with additions of exogenous humic materials for both the oxidized and non-oxidized soil as well as with time of PAH permanence in soil. PAH recoveries were lower in the non-oxidized soil, thereby revealing the importance of native organic matter in increasing PAH retention in soils. This study shows that mobility of PAHs in soils can be controlled by soil conditioning with humic substances.     

High Pressure Size Exclusion Chromatography (HPSEC) of humic substances: molecular sizes, analytical parameters, and column performance

High Pressure Size Exclusion chromatography (HPSEC) is increasingly used to evaluate molecular sizes of humic substances from different sources. Asymmetry factors (As), number of theoretical plates (N), coefficient of distribution (k(d)), and column resolution (Rs) were determined for two different HPSEC columns (TSK G3000SW and Biosep S2000) and polysaccharides of known molecular weights were used as standards. Calibration curves were equivalent for both columns whereas analytical parameters revealed that the TSK column was only slightly more efficient in separating polysaccharide standards. Mw and Mn values for humic substances differed according to the molecular weight range of each column but relative standard deviation never exceeded 5% for both columns. Variations between columns were attributed to intrinsic humic properties such as the stability of conformational structures. These results suggested that humic substances in solutions are loosely-bound association of small molecules that may be consistently dispersed by diffusion through size-exclusion pores. HPSEC is confirmed to represent a highly precise method to evaluate the relative molecular-size distribution of dissolved humic substances.