Testosterone levels in midtrimester maternal and fetal plasma and amniotic fluid

Testosterone was measured in maternal plasma (58 samples), amniotic fluid (71 samples) and fetal plasma (55 samples) in 79 patients between 15 and 23 weeks' gestation. Maternal plasma testosterone levels were unrelated to fetal sex. Amniotic fluid testosterone was significantly higher in male than female fetuses but did not reliably predict fetal sex. A correct diagnosis of fetal sex was made by testosterone assay of pure fetal plasma in 39 out of 40 males and in 15 out of 15 females using 1.70 nmol/1 as the cut-off value. This investigation is not the method of choice for routine fetal sexing but may be of value in fetuses suspected of having certain endocrine disorders.     

Spatial variation in 2-methyl-4-chlorophenoxyacetic acid mineralization and sorption in a sandy soil at field level

The phenoxyacetic acid herbicide MCPA (2-methyl-4-chlorophenoxyacetic acid) is frequently detected in groundwater beneath Danish agricultural fields. We investigated spatial variation in microbial MCPA mineralization potential in a flat agricultural field of fine sandy soil (USDA classification: Humic Dystrudept) located on the Yoldia plains of Northern Jutland, Denmark. Samples for determination of MCPA mineralization and sorption were collected from the Ap and Bs horizons at 51 sampling sites located in a 200 x 220 m grid. Spatial variation in sorption was low in both horizons (distribution coefficient, 0.36-4.16 L kg(-1)). Sorption correlated strongly with soil organic carbon content in both horizons (CV, 93 and 83%, respectively) and negatively with soil pH. [Ring-(14)C]-MCPA mineralized readily in the Ap horizon, with 49 to 62% of the (14)C-MCPA being converted to (14)CO(2) during the 67-d incubation period. With the subsoil, mineralization of (14)C-MCPA varied considerably between samples (0.5-72.8%). At neither depth was there correlation between (14)C-MCPA mineralization and sorption, soil pH, organic carbon content, clay content, number of colony-forming units (CFU), pseudomonad CFU, or any of the four microbial activity parameters measured. The presence of microbial genes encoding for the TfdA enzyme was quantified using real-time polymerase chain reaction. No correlation was found between MCPA mineralization potential and the natural background number of tfdA genes present in the soil samples. The degradation kinetics suggests that the high (14)C-MCPA mineralization rate detected in soil samples was linked to growth of the MCPA-degrading soil microbial community.     

Tetrachloroethylene Emissions and Exposure in Dry Cleaning

ABSTRACT

Tetrachloroethylene (PCE) emissions and the exposure of workers in six commercial and three industrial dry-cleaning establishments that use dry-to-dry machines were determined. The personal samples and area samples [8-hr time-weighted average (TWA) and short-term exposure] were collected with charcoal tubes and passive monitors. The temporal variation of PCE concentration in the workplace air was monitored using a Fourier transform infrared analyzer (FTIR). The PCE emission rates were determined by multiplying the average PCE concentration in the room and the total airflow rate in the room. The PCE emissions were related to the cleaning rate in units of kg/hr.

The operators' mean TWA exposure in commercial shops and industrial establishments was 28 (4.1 ppm) and 32 mg/m³ (4.6 ppm), and the pressers' exposure was 3.4 (0.5 ppm) and 7.7 mg/m³ (1.1 ppm), respectively. The customer service personnel had the lowest TWA exposure with a mean value of 0.8 mg/m³ (0.1 ppm). The highest peak concentration (2300 mg/m³; 334 ppm) was observed during cleaning of the lint and button trap, during which operation respirators were used. The PCE emission rates ranged from 4 to 118 g/hr corresponding to emission factors (mass of solvent evaporated per mass of cleaned cloths) of 0.3–3.6 g/kg. The workers' exposure to PCE was below the occupational limit values in the United States [according to the American Conference of Governmental Industrial Hygienists (ACGIH)] and in Finland. The outdoor PCE emissions were clearly below the limit values given in the European Union volatile organic compound (VOC) directive requirements.     

Sorption of SO2 on Ground Nahcolite Ore

Large quantities of nahcolite ore, a naturally occurring mineral containing between 70 and 90% sodium bicarbonate are known to occur in the Green River Formation of the Piceance Creek Basin of northwestern Colorado.¹ Deposits occur in two major forms, as either bedded or disseminated ore. In the latter case, the host rock is oil shale, a dolomitic marlstone containing kerogen material. Bench and pilot scale studies have shown finely divided nahcolite ore to be an effective SO₂ sorbent in baghouse filters.² These studies form the basis of the nahcolite ore injection process as a means for controlling SO₂ emissions to the environment.³ Although there have been published investigations of reactions of SO₂ with Na₂CO₃and NaHCO_3, ⁴ no reference could be found to a systematic study of nahcolite ore reacting with SO₂.     

Exploring Patterns of Seafood Provision Revealed in the Global Ocean Health Index

Sustainable provision of seafood from wild-capture fisheries and mariculture is a fundamental component of healthy marine ecosystems and a major component of the Ocean Health Index. Here we critically review the food provision model of the Ocean Health Index, and explore the implications of knowledge gaps, scale of analysis, choice of reference points, measures of sustainability, and quality of input data. Global patterns for fisheries are positively related to human development and latitude, whereas patterns for mariculture are most closely associated with economic importance of seafood. Sensitivity analyses show that scores are robust to several model assumptions, but highly sensitive to choice of reference points and, for fisheries, extent of time series available to estimate landings. We show how results for sustainable seafood may be interpreted and used, and we evaluate which modifications show the greatest potential for improvements.     

Alarm signal response in the brittle star Amphiura filiformis

 Flat fishes, such as the dab Limanda limanda, commonly prey on arms of Amphiura filiformis. We demonstrate in flume experiments that A. filiformis showed a more or less simultaneous response to an up-stream predation by dab on conspecifics: the arms, which are stretched up into the water column when filter feeding, responded by bending down to the sediment surface, and some arms submerged, at least partly, into the sediment. We interpret this as an alarm response. A similar, but significantly weaker response in A. filiformis was also recorded when dab ate Amphiura chiajei. Homogenates of the two Amphiura species and arm pinching – to simulate partial predation – elicited a similar response in A. filiformis, the arms bent to the sediment surface. In contrast, however, the behavioural response of the arms to the homogenates was to protrude further out of the sediment and sweep the surface vigorously. We interpret this as a feeding behaviour. Response to arm pinching was less clear. The ecological consequences and origin of alarm signal response in A. filiformis are discussed. Received: 8 February 1999 / Accepted: 16 July 1999     

Energy flow model of an oxygen-deficient estuary on the Swedish west coast

The estuary Byfjord (Sweden) is characterized by high primary production, a well developed meiofauna compared to the macrofauna, high epifaunal biomass, a low number of herbivorous copepods and a small fish stock. A simplified energy flow model of the ecosystem of the fjord is given. The energy transfer is approximated to 15%. About one-fourth-300 (metric) tons of carbon — of the annual primary production is suggested to be directly consumed and to produce 5 tons of zooplankton carbon and 40 tons of epifaunal (mainly Mytilus edulis) carbon. About 500 tons of carbon from the detritus pool are probably utilized in animal production. This amount will produce 5 tons of zooplankton carbon, 6 tons of meiofaunal carbon, and 3 tons of carbon from the benthic macrofauna. Production of fish is estimated at 0.3 ton carbon per year. M. edulis seems to be the only food resource in the fjord worth harvesting by man.