An environmental assessment of enhanced oil recovery

The objective of this assessment is to quantify some of the environmental effects of a significant increase in United States oil production by tertiary or enhanced oil recovery (EOR) methods. The problems associated with each EOR technology are discussed and controls and regulations are briefly summarised. A tertiary oil production scenario for the United States was developed focussing only on mainland fields in the lower 48 states. It included all of the EOR methods expected to be in use during the next two decades. The environmental impacts, including water requirements, air emissions and generation of solid wastes, are then scaled to this scenario. The effects of control technologies and state regulations are considered. A comparison is also made between the impacts of EOR as an energy source and impacts associated with coal and synthetic fuels which concludes that EOR is preferable in many respects. There are environmental risks associated with EOR technologies, specific projects and specific fields in the production scenario; however, most problems are solvable by responsible regulation, enforcement of regulations and application of the best professional engineering by project operators.     

ZOOPLANKTON AND DREDGING: RESEARCH PERSPECTIVES FROM A CRITICAL REVIEW1

ABSTRACT: Studies on the responses of zooplankton to dredging are summarized and discussed. Design criteria for studies intended for impact assessment require careful consideration of sampling due to the highly variable spatial and temporal distributions of zooplankton. It is suggested that ocean dominated systems present different research requirements than those estuarine regions which have endemic zooplankton populations.     

Clinical significance of persistent amniotic fluid leakage after genetic amniocentesis

Chronic amniotic fluid leakage is a rare complication of genetic amniocentesis. Pregnancy outcomes in two such patients are presented and six previous cases reviewed. Although chorioamnionitis has not been reported, potentially serious complications may occur including an increased risk for pre-term delivery and fetal skeletal deformity. While conservative management of post-amniocentesis amniotic fluid leakage is advocated, patients should be advised of these risks.     

Stoffhaushalt von Auen?kosystemen: B?den und Hydrologie, Schadstoffe, BewertungenHrsg: K. Friese, B. Witter, G. Miehlich, M. Rode Verlag: Springer Verlag, Heidelberg, 2000, 434 S., 196 Abb., 79 Tabellen, ISBN 3-540-67068-8, DM 169,-

Buchpr?sentationen

Stoffhaushalt von Auen?kosystemen: B?den und Hydrologie, Schadstoffe, BewertungenHrsg: K. Friese, B. Witter, G. Miehlich, M. Rode Verlag: Springer Verlag, Heidelberg, 2000, 434 S., 196 Abb., 79 Tabellen, ISBN 3-540-67068-8, DM 169,-     

Modelling effects of time-variable exposure to the pyrethroid beta-cyfluthrin on rainbow trout early life stages

Background

Available literature and regulatory studies show that the severity of effects of beta-cyfluthrin (a synthetic pyrethroid) on fish is influenced by the magnitude and duration of exposure. To investigate how the exposure pattern to beta-cyfluthrin (constant vs peak) may influence the response of the fish, we used a mechanistic effect model to predict the survival and growth of the rainbow trout over its early life stages (i.e. egg, alevin and swim-up fry). We parameterized a toxicokinetic–toxicodynamic (TKTD) module in combination with a dynamic energy budget model enabling us to describe uptake and elimination, as well as to predict the threshold concentration for survival and sublethal effects (feeding behaviour and growth). This effect model was calibrated using data from an early life stage experiment where trout was exposed to a constant concentration of cyfluthrin. The model was validated by comparing model predictions to independent data from a pulsed-exposure study with early life stages of rainbow trout.

Results

The co-occurrence of effects on behaviour and growth raised the possibility that these were interrelated, i.e. impairment of feeding behaviour may have led to reduced food intake and slower growth. We, therefore, included ‘effect on feeding’ as mode of action in the TKTD module. At higher concentrations, the constant exposure led to death. The model was able to adequately capture this effect pattern in the calibration. The model was able to adequately predict the response of fish eggs, alevins and swim-up fry, from both the qualitative (response pattern) and quantitative points of view.

Conclusions

Since the model was successfully validated, it can be used to predict survival and growth of early life stages under various realistic time-variable exposure profiles (e.g. profiles from FOCUS surface water modelling) of beta-cyfluthrin.