Hypoxia in the Gulf of Mexico

Seasonally severe and persistent hypoxia, or low dissolved oxygen concentration, occurs on the inner- to mid-Louisiana continental shelf to the west of the Mississippi River and Atchafalaya River deltas. The estimated areal extent of bottom dissolved oxygen concentration less than 2 mg L-1 during mid-summer surveys of 1993-2000 reached as high as 16,000 to 20,000 km2. The distribution for a similar mapping grid for 1985 to 1992 averaged 8000 to 9000 km2. Hypoxia occurs below the pycnocline from as early as late February through early October, but is most widespread, persistent, and severe in June, July, and August. Spatial and temporal variability in the distribution of hypoxia exists and is, at least partially, related to the amplitude and phasing of the Mississippi and Atchafalaya discharges and their nutrient flux. Mississippi River nutrient concentrations and loadings to the adjacent continental shelf have changed dramatically this century, with an acceleration of these changes since the 1950s to 1960s. An analysis of diatoms, foraminiferans, and carbon accumulation in the sedimentary record provides evidence of increased eutrophication and hypoxia in the Mississippi River delta bight coincident with changes in nitrogen loading.     

Prenatal diagnosis of thrombocytopenia absent radius syndrome by ultrasound and cordocentesis

The prenatal diagnosis of thrombocytopenia absent radius (TAR) syndrome, utilizing ultrasound and cordocentesis, is described. To our knowledge, this represents the first prenatal diagnosis of this condition in an index case. The diagnostic evaluation of a fetus with upper extremity limb reduction defects is discussed.     

Lichen response to changes in atmospheric sulphur: isotopic evidence.

In June of 1997, several thalli of the lichen species Alectoria sarmentosa were transplanted from a remote area (Bonavista) to an urban area (St John's) on the island of Newfoundland, Canada. The purpose was to assess the response of these epiphytic lichens to a change in the level of atmospheric sulphur pollution as measured by sulphur concentration and isotopic composition. The dominant source of atmospheric sulphur in the Bonavista area is sea spray, therefore, lichens growing there have relatively high sulphur isotopic compositions and low concentrations (approximately + 15 per/thousand, 250 ppm). Atmospheric sulphur in the St John's area is dominated by anthropogenic sources, primarily oil burning. Lichens in this area have lower isotopic compositions and higher concentrations (approximately + 6 per thousand, 500 ppm). The transplanted lichens were monitored monthly for a period of 1 year. In all experiments the sulphur isotopic composition decreased and the sulphur concentration increased linearly. It is estimated that, within 18 months, transplanted A. sarmentosa would be indistinguishable from the same species naturally growing in the transplant site, both in terms of sulphur concentration and isotopic composition.     

Some Air Pollution Problems Associated with Agriculture in Texas

A report of some experiences with air pollution problems associated with the cotton ginning industry and the application of agricultural insecticides and herbicides.     

Risk-taking and environmental perception

This paper investigates the relationship between pupils' environmental perception (in terms of preservation and utilisation of nature) and personality (in terms of risk-taking). 713 secondary school pupils in Switzerland were investigated. Environmental perception was assessed via three factors: Preservation, Utilisation of Nature and Consideration for Conservation. Risk-taking was evaluated via six factors: Positive Risking, Ambivalence, Thrill in Gambling, Ineffective Control, Effective Control, and Anger Reaction. Analysis of the correlation matrix between Risk-taking and Environmental perception revealed three profiles (types): the high scorer on Preservation is the controlled and cautious gambler. The Utiliser (anthropocentric) profile is essentially a mirror image of the first: the Utiliser does not enjoy unpredictable risks, reacts with anger when risks fail and has little control over his/her own risk-taking behaviour. The Consideration for Conservation (ecocentric) profile assumes a position between these two profiles.     

A Strategy for the Evaluation of Sensory and Pulmonary Irritation Due to Chemical Emissions from Indoor Sources

Abstract

Sensory and pulmonary irritation are physiological responses to chemical exposure which result in characteristic, measurable changes in respiratory activity in mice. A standard method has been applied to the estimation of sensory irritation associated with a specific chemical exposure. This method has been correlated with human responses to these chemicals. Symptoms associated with chemical irritants are consistent with complaints due to problems with indoor air quality, which may include eye and upper respiratory tract irritation, headaches, and nausea. A stepwise strategy for assessing the contribution of indoor products to sensory and pulmonary irritation is discussed in the current paper. The strategy includes product emissions testing using dynamic environmental chambers, the selection of suspected irritants for respiratory irritation testing, respiratory irritation testing of individual compounds and representative mixtures using synthesized atmospheres, and the evaluation of test data to determine those compounds which may contribute to sensory and pulmonary irritation in humans. The current strategy is being applied to evaluate carpet system materials and their constituent chemicals.     

Climate change and indigenous natural resource management: a review of socio-ecological interactions in the Alinytjara Wilurara NRM region

This article examines key socio-ecological interactions identified during a climate change vulnerability assessment in the Alinytjara Wilurara natural resources management (NRM) region of South Australia. The complex local socio-ecological interactions are highlighted to guide a response to the challenge of adapting to climate change within the region. Recognising several key desert drivers which perpetuate degraded socio-ecological systems, this article recommends that a range of strategies be employed simultaneously to enhance local environmental management in association with remote indigenous communities, including: linking people and NRM more closely; tracking funding but ensuring systems can withstand periods of limited financial support; developing cross-sectoral and cross-institutional links; empowering and engaging communities; communicating effectively; and actively supporting local and traditional environmental knowledge. Unless climate change adaptation responses within the region are conceptualised and enacted within the context of complex local socio-ecological systems, NRM will not improve and social vulnerability will increase.     

Rapid measurement of indoor mass-transfer coefficients

Indoor air pollutant concentrations can be influenced by how rapidly species are transported to and from surfaces. Consequently, a greater understanding of indoor transport phenomena to surfaces improves estimates of human exposure to indoor air pollutants. Here, we introduce two methods of rapidly and directly measuring species fluxes at indoor surfaces, allowing us to evaluate the transport-limited deposition velocity, v_t (a mass-transfer coefficient). The deposition velocity sensor (DeVS) method employs a small microbalance coated with a pure hydrocarbon, preferably octadecane. We quantify flux (or evaporation rate) of the hydrocarbon into a room by observing the rate of mass loss on the microbalance. The transport-limited deposition velocity, v_t,octadecane, is then obtained by combining the flux with the vapor pressure of the hydrocarbon. Simultaneously, v_t,ozone is quantified using the deposition velocity of ozone (DeVO) method, which acts as a standard to calibrate and evaluate DeVS. Specifically, DeVO evaluates ozone transport to surfaces by quantifying the conversion by ozone of nitrite to nitrate on a glass fiber filter. Simultaneous laboratory chamber experiments demonstrates that v_t for octadecane and ozone are strongly correlated, with the values for ozone 1.5 times greater than that for octadecane. In an office experiments, the DeVS method responds within minutes to step changes in conditions such as occupancy, activities and ventilation. At present, the results are in order-of-magnitude agreement with predicted indoor mass-transfer coefficients.