Per- and polyfluorinated compounds in house dust and indoor air from northern Norway - a pilot study

Polyfluorinated compounds (PFCs) are an extremely versatile class of compounds and are used in a variety of consumer applications and products. Recent studies have suggested that PFCs in indoor air and dust could act as sources of human exposure and outdoor air contamination. This study presents method development and analysis of a wide range of PFCs in dust and air using active sampling techniques with commercially available sampling equipment (forensic nozzles with filter housings for dust collection and polyurethane foam (PUF)-XAD₂-PUF sandwich-tubes for air sampling) using both liquid and gas chromatography mass spectrometry. The developed method was validated and tested for applicability to analyze dust and air samples at both low and high concentrations (0.5 ng and 25 ng per analyte per air sample, respectively). Samples from private households and an office building were analyzed to explore differences in distribution patterns and concentrations. Perfluorooctane sulfonate, perfluorodecane sulfonate, perfluoroheptanoate, perfluorooctanoate and perfluorononanoate were observed in all samples of dust from private households, in the range from 1 to 80.1 ng g⁻¹. Fluorotelomer alcohols (FTOHs) were the predominant PFCs in indoor air samples with ∑FTOHs ranging between 4.7 and 17.9 ng m⁻³. The concentrations found in the present study are generally lower than those previously reported. This variation may be due to differences associated with geographical locations and lifestyles. However, use of different sampling techniques and strategies among studies can introduce large variations in PFC concentration found, making direct comparisons challenging.     

Modeling of Dry Injection Flue Gas Desulfurization

Dry processes for controlling sulfur dioxide emissions by injecting sodium based sorbents in the ductwork ahead of a bag filter are effective and more simple alternatives to conventional FGD processes. This paper presents a fundamental kinetic model of the dry injection process. Experimental data from pilot scale tests are reported. The model is shown to be applicable to the dry injection process. However, further experimental work is recommended to get a better understanding of the reaction mechanisms.     

Declining coastal piscivore populations in the Baltic Sea: Where and when do sticklebacks matter?

Intraguild predation interactions make fish communities prone to exhibit alternative stable states with either piscivore or prey fish dominance. In the Baltic Sea, local declines of coastal piscivores like perch (Perca fluviatilis) have been observed to coincide with high densities of sticklebacks (Gasterosteus aculeatus). Mechanisms behind this shift between piscivore and stickleback dominance were studied both experimentally and in field. Results showed that predation by sticklebacks has a strong negative effect on perch larvae survival, but this effect rapidly decreases with increasing perch size, likely due to gape limitations and digestion constraints in sticklebacks. Large spatial and temporal variations in patterns of stickleback migration into perch spawning sites were observed. Whether or not high density of sticklebacks will cause declines in coastal piscivore populations is suggested to depend on the availability of spawning sites in which sticklebacks do not migrate into or arrive late in the reproduction season of coastal piscivores.     

Nutritional condition and growth rate of anchovy larvae (Engraulis mordax) in the California Current: two contrasting years

A large number of northern anchovy larvae, Engraulis mordax, were collected in the Southern California Bight on two CalCOFI cruises during spring 1987, and the amounts of triacylglycerol, cholesterol and polar lipids were measured in each individual larva using the latroscan TLC/FID (thin-layer chromatography/flame ionization detection) system. The 1987 larvae were compared to larvae taken in the Bight during the previous year. Canonical correlation analyses revealed a significant relationship between the larval lipid components and physical/biological data collected at each occupied station during the late 1987 spring cruise, similar to that recorded in 1986. The short-term nutritional condition of the copepod Calanus pacificus was the most important station variable in both cruises. Their triacylglycerol:cholesterol ratio indicated that few of the 1987 larvae had been starving, but their very low contents of length-specific cholesterol and polar lipid indicated that they had been growing very slowly. Otolith readings on defatted larvae confirmed that the 1987 larvae had been growing significantly more slowly than the 1986 larvae. Furthermore, the data suggested that in the 1986 population the faster growing larvae were also those with the highest lipid content. This situation was reversed for the 1987 larvae, when the faster growing larvae in the population seemed to achieve their faster growth only at the expense of a lowered lipid content. The abundance of anchovy larvae was much higher in spring 1987 than in spring 1986 but, despite this, the apparent recruitment (number of Age 0 fish in July of each year) was not higher in 1987.     

Physiological responses ofCalanus finmarchicus andMetridia longa (Copepoda: Calanoida) during the winter-spring transition

The effect of pH on the biological availability of copper to the brine shrimp Artemia franciscana was studied with acclimated and non-acclimated individuals for the pH range 5.5 to 8.5. A chemical speciation model was used to calculate the speciation of copper in a chemically-defined saline solution as a function of pH. The lipid solubility of inorganic copper species was determined in hexadecane/saline and octanol/saline extraction systems. Copper is absorbed across the gut epithelium and accumulation is proportional to time over a 120 min experimental period. The biological availability of copper decreases with a decrease in the pH of the salt solution and a concomitant increase of the cupric ion concentration. Acclimation to the experimental pH has a marked effect on the uptake process, which depends on the buffer used. There is no extraction of copper in hexadecane, but a small amount goes in octanol. There is, however, no direct relation between the accumulation of copper in the shrimps and the extraction of copper in octanol. Multiple regression of the accumulation rates for non-acclimated animals on the calculated copper species concentrations shows that much of the variation in accumulation rate with pH is explained when copper hydroxide and/or copper carbonate species are considered to be the biologically available forms. Alternatively, the observations can be interpreted as the result of competitive binding of protons and copper species for carrier systems.     

Fluid motion and particle retention in the gill of Mytilus edulis: Video recordings and numerical modelling

Particle trajectories of 6.4m Latex spheres were recorded by video, both near an isolated blue mussel, Mytilus edulis, gill filament and, in place of an intact interfilamentary canal, in a model canal of width 200, 100 or 70m, formed by a transparent plate positioned next to a gill filament. Each arrangement was placed in a 2 x 10 x 10 cm test vessel filled with seawater. Serotonin (nerve-transmitter) stimulation was used to activate lateral cilia and to either lock latero-frontal cirri at the end of an active stroke (10^-5 M), or to activate them (10^-6 M), yielding lateral cilia beat frequencies of 19 and 16 Hz, respectively. With latero-frontal cirri locked, image analysis of particle tracks gave maximum velocities of ca. 2.9±0.2mm s^-1 close to the tips of lateral cilia, for both isolated filament and model canal cases. Experimental velocity profiles along the 200-m wide model canal were recorded and used as good approximations to the fluid velocity because of the low Reynolds number. A two-dimensional steady model was proposed for the gill pump, assumed to only comprise lateral cilia. This model was solved numerically for the experimental model, canal in the vessel and the results showed satisfactory agreement with experimental volocity profiles from particle tracks. The numerical approach was also applied to a model of a single interfilamentary canal in the vessel. The resulting mean velocity in the canal was 1.70 mm s^-1, but the resistance to flow in the model was less than that in an intact mussel gill. Video graphs of particle tracks indicated that active latero-frontal cirri play a role in the transfer of particles from through current to frontal current, probably by means of a strong interaction through the motion of intervening fluid rather than through a direct physical contact. M. edulis specimens used in the present study were collected in 1990 at Helsingør and in 1991 at Kerteminde, Denmark.     

The return of the giants: ecological effects of an increasing elephant population

Northern Botswana and adjacent areas, have the world's largest population of African elephant (Loxodonta africana). However, a 100 years ago elephants were rare following excessive hunting. Simultaneously, ungulate populations were severely reduced by decease. The ecological effects of the reduction in large herbivores must have been substantial, but are little known. Today, however, ecosystem changes following the increase in elephant numbers cause considerable concern in Botswana. This was the background for the "BONIC" project, investigating the interactions between the increasing elephant population and other ecosystem components and processes. Results confirm that the ecosystem is changing following the increase in elephant and ungulate populations, and, presumably, developing towards a situation resembling that before the reduction of large herbivores. We see no ecological reasons to artificially change elephant numbers. There are, however, economic and social reasons to control elephants, and their range in northern Botswana may have to be artificially restricted.     

Boating and navigation activities influence the recruitment of fish in a Baltic Sea archipelago area

We studied the effects of boating and navigation activities on the recruitment of coastal fish in the Stockholm archipelago in the NW Baltic proper. The impacts were quantified by sampling metamorphosed young-of-the-year (Y-O-Y) fish in inlets adjacent to i) routes for medium-sized passenger ferries; ii) berths (small marinas) with small boats; and iii) references. Species with high preference for vegetation were negatively influenced by boating and navigation activities and species with low preference positively influenced. Pike (Esox lucius) Y-O-Y were significantly more abundant in reference areas, while bleak (Alburnus alburnus) were more abundant in dredged marinas. No statistically significant patterns were identified for perch (Perca fluviatilis) although there was a trend of low abundance along ferry routes. Many species of nearshore fishes are dependent on submerged vegetation as spawning and larval substrate, structural refuge and feeding habitat. Our results suggest that the negative effects from boating and navigation activities on the coverage and height of vegetation, especially on species of Chara and Potamogeton spp., may contribute to changes in the Y-O-Y fish community.