Autecology of Fucus distichus ssp. distichus (Phaeophyceae: Fucales) in Nova Scotia,Canada

The autecology of Fucus distichus L. ssp. distichus was investigated at several sites on the Atlantic coast of Nova Scotia, Canada, throughout a 2-year period. This species is confined to high-littoral rock pools at exposed sites, where there appears to be little competition from other organisms. Water temperature, salinity, dissolved oxygen, and hydrogen-ion concentrations underwent both considerable seasonal and short-term variation. Pools with extremes of salinity did not contain F. distichus ssp. distichus. Receptacles are formed during winter, and by late spring they are cast. Sporelings were first visible during September; their development was slow, and these plants did not become reproductive until the second year. During the period February to May, rapid growth of new fronds occurred; an increase in both length and bulk of the plants resulted from this growth. Fronds of mature plants continued to elongate slowly throughout the summer and the early autumn with the formation of receptacles in winter. Plants were frequently damaged, which resulted in regeneration of new fronds from the wounded surface.Issued as NRCC No. 14510     

PCDDs, PCDFs, PCBs and HCB in marine and estuarine sediments from Queensland, Australia.

Concentrations of 2,3,7,8-chlorine substituted PCDDs, PCDFs, selected PCB congeners and HCB were determined in sediment samples collected from sites along the east coast of Queensland in northern Australia. PCDDs were detectable in all sediment samples while PCDFs, PCBs and HCB were mainly found in sediment samples collected from sites in the Brisbane metropolitan area. The results provide evidence that an unidentified source for higher chlorinated PCDDs exists along the Queensland coast.     

Phytoremediation of polyaromatic hydrocarbons, anilines and phenols

Phytoremediation technologies based on the combined action of plants and the microbial communities that they support within the rhizosphere hold promise in the remediation of land and waterways contaminated with hydrocarbons but they have not yet been adopted in large-scale remediation strategies. In this review plant and microbial degradative capacities, viewed as a continuum, have been dissected in order to identify where bottle-necks and limitations exist. Phenols, anilines and polyaromatic hydrocarbons (PAHs) were selected as the target classes of molecule for consideration, in part because of their common patterns of distribution, but also because of the urgent need to develop techniques to overcome their toxicity to human health. Depending on the chemical and physical properties of the pollutant, the emerging picture suggests that plants will draw pollutants including PAHs into the plant rhizosphere to varying extents via the transpiration stream. Mycorrhizosphere-bacteria and -fungi may play a crucial role in establishing plants in degraded ecosystems. Within the rhizosphere, microbial degradative activities prevail in order to extract energy and carbon skeletons from the pollutants for microbial cell growth. There has been little systematic analysis of the changing dynamics of pollutant degradation within the rhizosphere; however, the importance of plants in supplying oxygen and nutrients to the rhizosphere via fine roots, and of the beneficial effect of microorganisms on plant root growth is stressed. In addition to their role in supporting rhizospheric degradative activities, plants may possess a limited capacity to transport some of the more mobile pollutants into roots and shoots via fine roots. In those situations where uptake does occur (i.e. only limited microbial activity in the rhizosphere) there is good evidence that the pollutant may be metabolised. However, plant uptake is frequently associated with the inhibition of plant growth and an increasing tendency to oxidant stress. Pollutant tolerance seems to correlate with the ability to deposit large quantities of pollutant metabolites in the 'bound' residue fraction of plant cell walls compared to the vacuole. In this regard, particular attention is paid to the activities of peroxidases, laccases, cytochromes P450, glucosyltransferases and ABC transporters. However, despite the seemingly large diversity of these proteins, direct proof of their participation in the metabolism of industrial aromatic pollutants is surprisingly scarce and little is known about their control in the overall metabolic scheme. Little is known about the bioavailability of bound metabolites; however, there may be a need to prevent their movement into wildlife food chains. In this regard, the application to harvested plants of composting techniques based on the degradative capacity of white-rot fungi merits attention.     

An integrated assessment of estrogenic contamination and biological effects in the aquatic environment of The Netherlands

An extensive study was carried out in the Netherlands on the occurrence of a number of estrogenic compounds in surface water, sediment, biota, wastewater, rainwater and on the associated effects in fish. Compounds investigated included natural and synthetic hormones, phthalates, alkylphenol(ethoxylate)s and bisphenol-A. The results showed that almost all selected (xeno-)estrogens were present at low concentrations in the aquatic environment. Locally, they were found at higher levels. Hormones and nonylphenol(ethoxylate)s were present in concentrations that are reportedly high enough to cause estrogenic effects in fish. Field surveys did not disclose significant estrogenic effects in male flounder (Platichthys flesus) in the open sea and in Dutch estuaries. Minor to moderate estrogenic effects were observed in bream (Abramis brama) in major inland surface waters such as lowland rivers and a harbor area. The prevalence of feminizing effects in male fish is largest in small regional surface waters that are strongly influenced by sources of potential hormone-disrupting compounds. High concentrations of plasma vitellogenin and an increased prevalence of ovotestes occurred in wild male bream in a small river receiving a considerable load of effluent from a large sewage treatment plant. After employing in vitro and in vivo bioassays, both in situ and in the laboratory, we conclude that in this case hormones (especially 17 alpha-ethynylestradiol) and possibly also nonylphenol(ethoxylate)s are primarily responsible for these effects.     

Clearance of PCDD/Fs via the gastrointestinal tract in occupationally exposed persons.

A digestive tract mass balance was performed on six men with high body burdens of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Intake via food was measured by analyzing duplicate portions of the food consumed by the volunteers and excretion via feces was determined by quantitative collection and analysis of the feces. Blood samples were taken to determine the current body burden. The results showed that the quantity of non-metabolized chemical excreted in the feces clearly exceeded the uptake via food for all of the 2,3,7,8-substituted PCDDs and some of the PCDFs, indicating a significant clearance across the gastrointestinal tract. The concentrations of these PCDD/F congeners in blood and feces were highly correlated (r > 0.8), demonstrating that the fecal PCDD/F content was determined by the body burden. The half lives in the test persons due to fecal clearance of non-metabolized chemical were estimated from the excretion rate and the current body burden and ranged between 10 years (Cl8DD) and 33 years (2,3,4,7,8-Cl5DF). These were compared with the overall contaminant half-lives due to all clearance processes which were calculated from the body burden and the decrease in blood concentrations measured over several years. The fecal clearance of non-metabolized PCDD/F contributed on average between 37% (2,3,7,8-Cl4DD) and 90% (Cl8DD) to the total elimination. This indicates that the gastrointestinal pathway plays a decisive role in the clearance of most 2,3,7,8-subsituted PCDD/F congeners.     

Absch?tzung der Quecksilberexposition

Zusammenfassung  Ein quecksilberkontaminierter Altstandort dient als Beispiel für eine umweltmedizinische Beurteilung der Belastung der im Umfeld wohnenden Personen durch Quecksilberimmissionen. Dabei wird die innere Exposition für sieben verschiedene Altersgruppen bezüglich der KontaktmedienBoden, Luft undNahrungsmittel anhand von konventionell festgelegten Szenarien abgesch?tzt und ein Vergleich mit den epidemiologischen Ergebnissen eines Humanmonitorings angestrebt. Die standortspezifisch und pfadspezifisch durchgeführte Expositionsabsch?tzung stützt sich auf cine Vielzahl von unterschiedlichen Probenehmern sowie auf über mehrere Jahre durchgeführte Konzentrationsmessungen in den aufnahmerelevanten Kompartimenten. Sowohl die Berechnungen als auch die epidemiologischen Untersuchungen zeigen eine leichte Erh?hung der Quecksilberexposition, gemessen an strengen Richtwerten.      

Einsatz der Hasse-Diagrammtechnik zur vergleichenden Datenanalyse von Biomarkerantworten und ?kotoxikologischen Tests

Die ?kotoxikologie mu? sich mit biologischen Systemen und ihren Antworten auf schadstoffinduzierten Stre? auseinandersetzen. Die hierzu verwendete experimentelle Technik eilt dabei den M?glichkeiten dynamischer, proze?orientierter mathematischer Modellierung weit voraus. In dieser methodisch orientierten Arbeit werden Techniken aus der mathematischen Disziplin der Verbandstheorie vorgestellt, die eine Datenanalyse unter den Aspekten vergleichender Bewertung erlauben. Wichtige Ergebnisse sind dabei

Partitioning of polychlorinated biphenyls and hexachlorobenzene into human faeces

The dietary absorption of persistent lipophilic organic pollutants (PLOPs) in humans is believed to occur via partitioning of the chemical between the lumen and the wall of the digestive tract. As such, the partitioning properties of the lumen contents are a key factor governing absorption. In this study, the partitioning properties of faeces were measured for 11 polychlorinated biphenyls and hexachlorobenzene (HCB). Four volunteers participated in the study, each of them providing faeces from a normal diet and a vegetarian diet. The faeces/gas equilibrium partition coefficient K(FG) varied by over three orders of magnitude between the different compounds. A linear relationship between log K(FG) and log KOA, the octanol/air partition coefficient, was observed. The slope of the relationship was > 1, indicating that the solvent properties of faeces were less polar than those of octanol. For a given compound, KFG varied up to a factor of 2.8 between the individuals on a normal diet. The influence of the vegetarian diet on K(FG) was negligible for the two volunteers who simply deleted fish and animal products from their normal diet, but K(FG) increased on average by a factor of 2 in the two individuals who increased their consumption of less readily digestible whole grains and vegetables in their vegetarian diet. On the basis of K(FG), the fugacities in the faeces were calculated. They were found to be much lower than the fugacities in blood. It is hypothesised that this is due to a temporary decrease in the fugacity in the wall of the jejunum caused by absorption of dietary lipids that results in equilibration between the lumen contents and the wall of the digestive tract at a fugacity below that present in the blood and the rest of the body.     

Lost benefits and carbon uptake by protection of Indian plantations

There is a range of problems in assessing how protection of a specific forest to Reduce Emissions from Deforestation and forest Degradation (REDD+) affect global emissions of greenhouse gases. This paper shows how knowledge and information about the biophysical characteristics of forests can be combined with theories of forest management and economic behaviour to derive the impacts on global emissions of REDD+. A modelling experiment from India, where 10% of the forest plantations in eight different regions are protected, shows that the biophysical characteristics of forests are decisive for the global impacts on emissions. In regions with slow-growing forests, agents in the non-protected forests are able to increase their output significantly to fill the demand from the protected forests. This opportunity is strictly limited in regions with fast-growing forests. Therefore, prices increase far more in regions with fast-growing forests than in slow-growing forests. Over time, the markets for Indian forestry products contribute to reduce the resulting price differences across regions. When the carbon uptake from protected forests approaches zero, the leakage of emissions to other Indian forests is between 20 and 40%. Only a small part of this is international leakage. Combining different models also helps to identify knowledge gaps, and to distinguish gaps that potentially may be filled with data and new knowledge, and gaps due to different angling of modelling biophysical processes and modelling of economic behaviour.