Laser-induced fluorescence of polycyclic aromatic hydrocarbons: an approach to gas standards

Rapid methods are needed to analyse air pollutants such as polycyclic aromatic hydrocarbons (PAHs). Reliable semi-quantitative gas standards were required for the development of a laser-induced fluorescence (LIF) method for polycyclic aromatic hydrocarbon analysis, based on sampling of air onto multi-channel polydimethylsiloxane rubber traps. Easily constructed diffusion tubes provided naphthalene vapour at ~2 ng s⁻¹. A gas chromatographic fraction collection method for loading less volatile PAHs onto the traps from a flame ionization detector outlet was developed and optimized. The accuracy of the method, which can be further optimized, was sufficient for initial LIF screening tests to flag samples exceeding threshold PAH levels for subsequent quantitative GC–MS analysis.     

Biosorption of Phosphorus Using Alginate-Like Exopolymers: Investigation of Removal Mechanism,Kinetic and Thermodynamic Properties

Journal of Polymers and the Environment - The purpose of this study was to investigate the phosphorus (P) adsorption mechanism, kinetic, isothermal and thermodynamic parameters using alginate-like...     

Periodic Migration and Lowland Forest Refugia in a "Sedentary" Neotropical Bird, Wetmore's Bush-Tanager

Although the concept of tropical birds as sedentary is pervasive, evidence suggests many are not. Our grasp of movement status in tropical birds is decidedly poor, but the successful long-term conservation of these birds depends on such information. Sedentariness will likely doom much tropical avian diversity, but increased vagility is a two-edged sword: beneficial in promoting immigration, but detrimental in that more than one habitat may be required. Birds requiring more than one habitat may be unable to locate a particular type as landscape modifications increase. Our long-term data set from the Sierra de Los Tuxtlas in southern Veracruz, México, reveals infrequent, large-scale movements in a local highland endemic. Wetmore's Bush-Tanager ( Chlorospingus ophthalmicus wetmorei) seems occasionally dependent upon lowland forests (now greatly diminished) as a refugium from temporarily unsuitable highlands. Our data and observations lead us to three conclusions: 1) assumptions of sedentariness in tropical birds should be made with extreme caution; 2) normal, but periodic phenomena may be easily overlooked, even in relatively long-term studies; and 3) missing such phenomena jeopardizes the success of any conservation plan because over the long term a population may be dependent upon refugia only occasionally occupied.     

Identification of the cellular site of polychlorinated peptide biosynthesis in the marine sponge Dysidea (Lamellodysidea) herbacea and symbiotic cyanobacterium Oscillatoria spongeliae by CARD-FISH analysis

Populations of the sponge Dysidea (Lamellodysidea) herbacea, which host the cyanobacterium Oscillatoria spongeliae, vary in their production of polychlorinated peptides. Peptide natural products previously isolated from D. herbacea are often halogenated and include dysidin, dysidinin, and a series of chlorinated diketopiperazines. Strikingly, the distinctive leucine-derived trichloromethyl signature of these compounds is shared only with metabolites of the marine cyanobacterium Lyngbya majuscula, and includes such compounds as barbamide and nordysidinin. Genetic information available for the barbamide biosynthetic gene cluster was used to successfully polymerase chain reaction (PCR) amplify a barB1 homolog (dysB1) from D. herbacea samples collected in Papua New Guinea. Catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH) analysis showed that dysB1 oligonucleotide probes hybridized to sequences in the filamentous cyanobacterial symbiont O. spongeliae. Consistent with this finding, a D. herbacea/O. spongeliae collection devoid of the polychlorinated peptides did not contain the barB1 homologs.Communicated by P.W. Sammarco, Chauvin     

Stable nitrogen isotopes in octocorals as an indicator of water quality decline from the northwestern region of Cuba

Environmental Science and Pollution Research - Eutrophication is one of the causes of the degradation of reefs worldwide. The aim of this research is to determine if sewage discharge reaches the...