Contaminated sediments and bioassay responses of three macroinvertebrates, the midge larva Chironomus riparius, the water louse Asellus aquaticus and the mayfly nymph Ephoron virgo

Bioassays are widely used to estimate ecological risks of contaminated sediments. We compared the results of three whole sediment bioassays, using the midge larva Chironomus riparius, the water louse Asellus aquaticus, and the mayfly nymph Ephoron virgo. We used sediments from sixteen locations in the Dutch Rhine-Meuse Delta that differed in level of contamination. Previously developed protocols for each bioassay were followed, which differed in sediment pretreatment, replication, and food availability. The Chironomus bioassay was conducted in situ, whereas the other two were conducted in the laboratory. The measured endpoints, survival and growth, were related to contaminant levels in the sediment and to food quantity in water and sediment.

Only the response of A. aquaticus in the bioassay was correlated with sediment contamination. Food availability in overlying water was much more important for C. riparius and E. virgo, thereby masking potential sediment contaminant effects. We conclude that growth of A. aquaticus was depressed by sediment contamination, whereas growth of E. virgo and C. riparius was stimulated by seston food quantity. We discuss that the trophic state of the ecosystem largely affects the ecological risks of contaminated sediments.     

Acceleration of the Fe(III)EDTA(-) reduction rate in BioDeNO(x) reactors by dosing electron mediating compounds

BioDeNO(x), a novel technique to remove NO(x) from industrial flue gases, is based on absorption of gaseous nitric oxide into an aqueous Fe(II)EDTA(2-) solution, followed by the biological reduction of Fe(II)EDTA(2-) complexed NO to N(2). Besides NO reduction, high rate biological Fe(III)EDTA(-) reduction is a crucial factor for a succesful application of the BioDeNO(x) technology, as it determines the Fe(II)EDTA(2-) concentration in the scrubber liquor and thus the efficiency of NO removal from the gas phase. This paper investigates the mechanism and kinetics of biological Fe(III)EDTA(-) reduction by unadapted anaerobic methanogenic sludge and BioDeNO(x) reactor mixed liquor. The influence of different electron donors, electron mediating compounds and CaSO(3) on the Fe(III)EDTA(-) reduction rate was determined in batch experiments (21mM Fe(III)EDTA(-), 55 degrees C, pH 7.2+/-0.2). The Fe(III)EDTA(-) reduction rate depended on the type of electron donor, the highest rate (13.9mMh(-1)) was observed with glucose, followed by ethanol, acetate and hydrogen. Fe(III)EDTA(-) reduction occurred at a relatively slow (4.1mMh(-1)) rate with methanol as the electron donor. Small amounts (0.5mM) of sulfide, cysteine or elemental sulfur accelerated the Fe(III)EDTA(-) reduction. The amount of iron reduced significantly exceeded the amount that can be formed by the chemical reaction of sulfide with Fe(III)EDTA(-), suggesting that the Fe(III)EDTA(-) reduction was accelerated via an auto-catalytic process with an unidentified electron mediating compound, presumably polysulfides, formed out of the sulfur additives. Using ethanol as electron donor, the specific Fe(III)EDTA(-) reduction rate was linearly related to the amount of sulfide supplied. CaSO(3) (0.5-100mM) inhibited Fe(III)EDTA(-) reduction, probably because SO(3)(2-) scavenged the electron mediating compound.     

Arsenic and sulfur nanoparticle synthesis mimicking environmental conditions of submarine shallow-water hydrothermal vents

Arsenic and sulfur mineralization is a natural phenomenon occurring in hydrothermal systems where parameters like temperature and organic matter(OM) can influence the mobilization of the toxic metalloid in marine environments. In the present study we analyze the influence of temperature and OM(particularly sulfur-containing additives) on As and S precipitation based on the recent discovery of As-rich nanoparticles in the hydrothermal system near the coast of the Greek island Milos. To this end, ...     

Setting national emission ceilings for air pollutants: policy lessons from an ex-post evaluation of the Gothenburg Protocol

The Gothenburg Protocol set national emission ceilings for transboundary air pollutants in 2010. These ceilings were formulated in 1999 using the Regional Air Pollution Information and Simulation (RAINS) model and national forecast data. The 2010 ceiling deadline is approaching as is a revision process which may lead to the setting of emission ceilings for 2020. This paper considers the original 1999 projections of six countries that were used within the RAINS model to inform the setting of their respective Gothenburg Protocol 2010 emission ceilings. These data are then contrast against recent inventory data and contemporary short-term forecasts out to 2010. These recent forecasts indicate that major downward shifts in the trends of pollutant emissions have been achieved, and whilst compliance challenges remain, there is a clear indication of the potential of such international agreements and their associated legislative and policy driven mechanisms. However, in a process governed by a maxim of achieving international environmental objectives at ‘least-cost’, the recent experience offers some valuable lessons. Specifically, in relation to the accuracy of energy projections and assumptions of other relevant variables in the modelling process. This paper considers these lessons and opens a discussion on the role of more adaptable mechanisms for the ongoing management of international agreements with long-term compliance horizons.     

Ultrasound diagnosis of fetal abnormalities and cytogenetic evaluation

Over a 65½ year period, in 288 pregnancies a variety of fetal malformations were detected by ultrasound. Two hundred and ten fetuses (73 per cent) were karyotyped. Gestational age at detection ranged from 11 to 38 weeks. The incidence of an abnormal karyotype in the total series was 14 per cent and 14.7 per cent in the 210 pregnancies in which a karyotype was performed. Single structural anomalies were found in 149 cytogenetically investigated fetuses, of which 25 had a chromosomal abnormality (17 per cent). Multiple structural malformations were present in 61 fetuses, of which 16 had an abnormal karyotype (26 per cent). Trisomy 18 was the most frequent finding. The most constant ultrasound finding in cases of an abnormal karyotype was polyhydramnios and severe IUGR in combination with structural defects. There is a need for extensive detailed ultrasound examination in high-risk pregnancies.     

Swimming obstructed by dead-water

In nautical literature, ‘dead-water’ refers to the obstructive effect encountered by ships moving in stratified water due to the ship generating waves on an interface that separates different water masses. To investigate the hypothesis that open water swimming may also be obstructed by an encounter of dead-water, possibly causing drowning, we performed two experiments that assess the impact of stratified water on swimming. In the first experiment, subjects made a single front-crawl stroke while lying on a carriage that was rolling just above the water surface. The gain in kinetic energy, as a result of the stroke, was far less in stratified than in homogeneous water. In the second experiment, four subjects swam a short distance (5 m) in homogeneous and in two different settings of stratified water. At the same stroke frequency, swimming in stratified conditions was slower by 15%, implying a loss in propulsive power by 40%. Although in nature stratification will be less strong, extrapolation of the results suggests that dead-water might indeed obstruct swimming in open water as well. This effect will be most pronounced during fair weather, when stratification of a shallow surface layer is most easily established. Our findings indicate that swimmers’ anecdotal evidence on ‘water behaving strangely’ may have to be taken more seriously than previously thought.