Ambient air concentrations of PCDDs,PCDFs, coplanar PCBs,and PAHs at the Mississippi Sandhill Crane National Wildlife Refuge,Jackson County,Mississippi

Our objective was to determine the levels of selected airborne contaminants in ambient air at the Mississippi Sandhill Crane National Wildlife Refuge, Mississippi, that might be affecting the health of endangered cranes living there. Two high-volume air samplers were operated at separate locations on the Refuge during May–September 1991. The sampling media were micro-quartz filters in combination with polyurethane foam plugs. Composite bimonthly samples from each station were analyzed for polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), coplanar polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs). Overall, residue concentrations were low. The toxic PCDD isomer 2,3,7,8-tetra-CDD was not detected, nor was penta-CDD. There was no difference (P>0.05) in residue concentrations between stations or over time and meteorological parameters were not correlated with residue concentrations. Because contaminant levels and patterns may differ seasonally, we recommend that air samples collected during winter months also be analyzed for these same chemical groups.     

Detection of low-grade mosaicism in fetal cells isolated from maternal blood

Recovering and analysing fetal erythrocytes from maternal blood is being pursued for non-invasive prenatal genetic diagnosis. We report the observation of 46, XY/47, XXY mosaicism in fetal cells from a woman whose first-trimester chorionic villus sampling (CVS) initially showed only 46, XY. Only after exhaustive (500 cells) analysis were four XXY cells found in cultured villi.     

Vitamins,folic acid and neural tube defects: Comments on investigations in the United States

No clear answer concerning whether multivitamin/folate supplementation prevents neural tube defects (NTDs) is provided by three studies in the United States. All these studies are occurrence in nature, no recurrence studies having been conducted. The Atlanta Birth Defects Study is subject to pronounced memory and recall biases, the length between event and interview being as long as 16 years. In a second study (Boston University), objections can be raised to certain aspects of the experimental design, and the claim that 22 per cent of women started vitamins sufficiently early after pregnancy diagnosis to influence NTD formation is suspicious. Our NICHD case control study of 541 women in California and Illinois revealed no evidence for multivitamins or folic acid preventing NTDs. U.S. public policy-makers face difficulties in applying results of recurrence or occurrence studies in high-risk areas to low-risk areas in the U.S.     

Anatomic correlates of ultrasonographic prenatal diagnosis

In utero sonographic diagnoses from forty-five malformed infants were correlated with their autopsy findings. Fifty-two malformations were diagnosed prenatally in 42 of the patients but 90 additional malformations were not. Nine sonographically diagnosed abnormalities were not confirmed at autopsy. Factors compromising sonographic diagnosis included: limited examinations, small fetal size, timing of examination, oligohydramnios, fetal position, nature of the malformation and unfamiliarity of the ultrasonographer with specific malformation syndromes. In vitro ultrasonography is an invaluable tool of diagnosing congenital malformations but has limitations.     

Local Perceptions of Changes in Traditional Ecological Knowledge: A Case Study from Malekula Island,Vanuatu

Traditional ecological knowledge (TEK) is a critical global resource that may be eroding amid social and environmental change. Here, we present data on local perceptions of TEK change from three communities on Malekula Island in Vanuatu. Utilizing a structured interview (n = 120), we find a common perception of TEK loss. Participants defined two key periods of TEK erosion (roughly 1940–1960 and 1980–present), and noted that TEK decline was driven both external (e.g., church) and internal (e.g., shifting values) processes. Erosion was perceived to more comprehensive in the worldview domain than in aspects of ethnobiological knowledge and practice. These data indicate the perceived fragility of TEK systems and the complexity of TEK change. TEK systems are critical to natural resource management, and data such as these will assist in designing nuanced responses to the ongoing loss of cultural knowledge and practice.     

A study of the effect of physical and chemical stressors on biological integrity within the San Diego hydrologic region

Environmental agencies across the United States have searched for adequate methods to assess anthropogenic impacts on the environment. Biological assessments, which compare the taxonomic composition of an aquatic assemblage to relevant biocriteria, have surfaced as an effective method to assess the ecological integrity of US waterbodies. In this study, bioassessment data were collected and analyzed in conjunction with physical habitat and chemical stressor data for streams and rivers within the San Diego basin from 1998 through 2005. Physical stressors such as sediment loading, riparian destruction, and in-stream habitat homogenization affect many locations in the region. However, physical habitat measures alone were found to frequently overestimate the biological integrity of streams in the region. Many sites within the San Diego Basin, although unaffected by physical stressors, continue to exhibit low biological integrity scores. Sites with low biological integrity tend to possess higher specific conductance and salinity compared to sites with high biological integrity. We suggest that one possible reason for these differences is the source water used for municipal purposes.     

Radium and radium-daughter nuclides in carbonates: a brief overview of strategies for determining chronologies

Radium isotopes have been used extensively to trace the movement of groundwater as well as oceanic water masses, but these radionuclides (and their daughters) are also useful chronometers for the determination of the time scales of other Earth and environmental processes. The purpose of this overview is to present the application of Ra and Ra daughters in the dating of carbonates. We show that the choice of dating method (decay of excess radionuclide or ingrowth of daughter) depends strongly on the parent/daughter activity ratios in the water in which the carbonate was precipitated. Thus freshly precipitated carbonates uniformly show excesses of ²²⁶Ra relative to its parent ²³⁰Th, and ²²⁶Ra decay can provide ages of carbonates over Holocene time scales. In contrast, carbonates are precipitated in waters of greatly varying ²¹⁰Pb/²²⁶Ra. Corals, deep-sea hydrothermal vent clams and the shelled cephalopod Nautilus live in waters with significant dissolved ²¹⁰Pb and all show excesses of ²¹⁰Pb in their carbonate. Bivalve molluscs from nearshore and coastal waters, and carbonates deposited from groundwater environments (e.g. travertines) in which ²¹⁰Pb is efficiently scavenged from solution, show deficiencies of ²¹⁰Pb relative to ²²⁶Ra. In contrast, fish otoliths strongly discriminate against ²¹⁰Pb regardless of the environment in which the fish lives. Deficiencies of ²²⁸Th relative to ²²⁸Ra are common in all carbonates. Useful time ranges for the ²¹⁰Pb/²²⁶Ra and ²²⁸Th/²²⁸Ra chronometers are ∼100 y and ∼10 y, respectively.