Quantitation of Stack Gas Flow

The presently available standards for measurement of gas flow in stacks and industrial flues are reviewed. Various problems associated with probe traverse techniques using the pitot-static tube, the Type S pitot tube, a directional type pitot tube, and hot wire anemometers are described. Recommendations are made with respect to the selection of velocity measurement station, and the selective application of velocity measurement devices is discussed.     

Genetic differentiation and reproductive incompatibility among Baja California populations of the copepod Tigriopus californicus

Populations of the harpacticoid copepod Tigriopus californicus were sampled from five sites from San Diego, California, to Playa Altamira, Baja California, Mexico. Allozyme analyses revealed that all the study populations are sharply differentiated genetically. At the extreme, two populations, Punta Baja and Playa Altamira, have no alleles in common at the seven allozyme loci studied. All pairwise interpopulation crosses successfully produced F₂ hybrids except those involving the Playa Altamira population. All crosses using Playa Altamira females failed to produce F₁ hybrids, while Playa Altamira males successfully produced F₁ progeny with females from all other sites. These F₁ offspring, however, were completely sterile (with San Diego and Punta Banda females) or only occasionally produced F₂ offspring (with Punta Morro and Punta Baja females). These results suggest that allopatric differentiation among Baja populations has resulted in exceptionally high levels of genetic divergence and nearly complete reproductive isolation of the Playa Altamira population, which should now be recognized at the semispecies (or perhaps sibling species) level.     

An increased incidence of haemangiomas in infants born following chorionic villus sampling (CVS)

The incidence of haemangiomas was ascertained by questionnaire in infants born to 578 consecutive CVS patients and 445 consecutive mid-trimester amniocentesis patients seen at a single institution between 1 January 1989 and 31 May 1991. The incidence of 7·4 per cent reported in the amniocentesis group was comparable to previous estimates of the incidence of haemangiomas in the general population. In contrast, a 21·1 per cent incidence, three-fold higher than that observed in the amniocentesis group, was observed among CVS-exposed infants (P<0·001). This increased incidence was largely confined to patients undergoing a transcervical procedure. No correlation was observed between the incidence of haemangiomas and gestational age at sampling, sample size, number of sampling attempts, or a history of bleeding following the procedure.     

The Science of Adaptation: A Framework for Assessment

Mitigation and Adaptation Strategies for Global Change - This paper outlines what is meant by "adaptation" to climate change, and how it might be addressed in the IPCC Assessments. Two...     

Octachlorodibenzo-p-dioxin in wood treatment materials and treated wood

The octachlorodibenzo-p-dioxin (OCDD) concentrations have been determined in aged samples of commercial pentachlorophenol (PCP), in wood protection formulations containing PCP and in wood treated with PCP as a preservative or as an anti-sapstain treatment. The concentrations of OCDD found in the various samples are within the range expected from the amount of commercial PCP initially present in the samples. In view of the known stability of OCDD the results are interpreted as indicating that the formulation, treatment and ageing processes have not led to any substantial conversion of PCP to OCDD; although one result indicates that outdoor exposure of treated samples increased the OCDD concentration by a factor of approximately 2 after $\text{3}\text{1}\text{2}$ years. Analysis of aged samples of treated wood indicate that OCDD is lost much less rapidly from the wood than PCP.     

In situ exposures using caged organisms: a multi-compartment approach to detect aquatic toxicity and bioaccumulation

An in situ toxicity and bioaccumulation assessment approach is described to assess stressor exposure and effects in surface waters (low and high flow), the sediment-water interface, surficial sediments and pore waters (including groundwater upwellings). This approach can be used for exposing species, representing major functional and taxonomic groups. Pimephales promelas, Daphnia magna, Ceriodaphnia dubia, Hyalella azteca, Hyalella sp., Chironomus tentans, Lumbriculus variegatus, Hydra attenuatta, Hexagenia sp. and Baetis tibialis were successfully used to measure effects on survival, growth, feeding, and/or uptake. Stressors identified included chemical toxicants, suspended solids, photo-induced toxicity, indigenous predators, and flow. Responses varied between laboratory and in situ exposures in many cases and were attributed to differing exposure dynamics and sample-processing artifacts. These in situ exposure approaches provide unique assessment information that is complementary to traditional laboratory-based toxicity and bioaccumulation testing and reduce the uncertainties of extrapolating from the laboratory to field responses.