Inventories and Distribution of Radiocaesium in Arctic Marine Sediments: Influence of Biological and Physical Processes

Extensive surveys of sediment burdens of radiocaesium, specifically ¹³⁷Cs, and other radioactive contaminants in the Arctic during the 1990's, indicate that almost all anthropogenic radionuclides buried on continental shelves adjacent to Alaska are derived from global bomb fallout. the ¹³⁷Cs (half-life: 30.2y) activities observed in surface (0-4 cm) marine sediments however, vary widely, albeit much less than the expected current inventory resulting from bomb fallout at this latitude (∼100mBq cm^-2). This observed geographical variation provided the opportunity to evaluate physical and biological mechanisms that may affect caesium biogeochemistry on Arctic continental shelves. We investigated whether high biological productivity in portions of the Bering and Chukchi Seas is effective in removing dissolved radiocaesium from the water column, and whether biological production in overlying water affects total radiocaesium inventories in sediments. Based upon C/N ratios in the organic fraction of shallow sediments, we found no evidence that higher inventories or surface activities of radiocaesium are present in areas with higher deposition of particulate organic matter. Based upon stable carbon isotope ratios of organic matter in sediments, we found no evidence that terrestrial runoff contributes proportionally to higher surface activities, although terrestrial runoff may affect total inventories of the radionuclide. Radiocaesium content of surface sediments was significantly correlated with total organic carbon content of sediments and the proportion of sediments in the finest sediment fractions. Because high current flow can also be expected to influence distributions of those sedimentary parameters, we conclude that re-distribution of     

Cadmium speciation and accumulation in periphyton in a small stream with dynamic concentration variations

Accumulation of cadmium in periphyton was investigated under field conditions while Cd concentration and speciation were dynamically varying in a small stream during rain events. Speciation in water was determined in situ by diffusion gradient in thin-films (DGT) and by modeling of complexation with fulvic acids. During the rain events, dissolved Cd concentrations increased from 0.17 nM to 0.27-0.36 nM, and 70-97% were DGT-labile. Cd content in periphyton closely followed Cd concentrations in water, despite higher concentrations of Zn and Mn, and may be controlled by either free or DGT-labile Cd concentrations. Decrease of Cd content in periphyton after the rain events was slower than the decrease of Cd concentration in water. Concentrations of Zn, Mn, Cu, Pb and Fe in periphyton also followed the dynamic variations of metal concentrations in water. Repeated exposure of periphyton to elevated dissolved Cd may lead to Cd accumulation.     

On the importance of size of plastic fragments and pellets on the strandline: a snapshot of a Brazilian beach

Virgin plastic pellets and plastic fragments are reported as ubiquitous beach contaminants in the peer-reviewed literature. A surface density of 0.3 virgin plastic pellets and plastic fragments per square centimeter of the strandline area was registered on an urban beach of the northeast of Brazil. This beach is presently not affected by petrochemical facilities or pellet processing plants. The main source of fragments (96.7%) was attributed to the breaking down of larger plastic items deposited on the beach. In the case of virgin plastic pellets (3.3%), the main sources were the marine environment and possibly nearby port facilities. This category of plastic pollutant offers particular threats to the marine environment and to beach users.     

Cover Image

The cover image is based on the Original Article Noninvasive prenatal paternity testing by means of SNP-based targeted sequencing by Jacqueline Chor Wing Tam et al., https://doi.org/10.1002/pd.5595 .

     

Diagnosis and significance of cystic hygroma in the first trimester

Thirty cases of cervical cystic hygroma were diagnosed in the first trimester of pregnancy. Karyotype analysis was available in 29 (97 per cent). Fifteen (52 per cent) had a chromosomal abnormality. The ultrasound appearance was described as posterior cervical, lateral cervical, or cervical hygroma with hydrops. Of the 14 euploid embryos, six were electively aborted, two are undelivered, and six have been delivered as phenotypically normal infants. In cases in which the chromosomes were normal and the pregnancy continued, all lesions resolved by 18 weeks.     

The rise and fall of new knowledge interests in the Dutch environmental movement

Summary Since the late 1960s concern about the pollution of our physical environment has grown into a social and political issue. In this process of increasing awareness, environmental activists have played a catalysing role in most Western countries. Moreover the environmentalists formulated an alternative set of ideas and strategies concerning the production and use of knowledge. These new knowledge interests were organised around three dimensions: cosmology, technology, and the organisation of knowledge production. On the basis of a case-study of Dutch environmentalism this paper tries to demonstrate how the articulation of these new knowledge interests of international scope actually occurred in the particular Dutch national setting. The analysis shows that many of the ideas brought forward in the course of time by Dutch environmentalists have been imported from abroad, especially from the United States, Great Britain and West Germany. However, the specific ways in which Dutch environmentalists have defined the content of their own knowledge interests have depended very much on the particularities of the political culture and socio-economic climate of the Netherlands, as well as the internal dynamics within the various environmental groups themselves.Dr Jacqueline Cramer was until very recently a member of staff in the Department of Science Dynamics at the University of Amsterdam. She has now moved to the TNO Centre for Technology and Policy Studies, P.O. Box 541, 7300 AM, Apeldoorn, The Netherlands. This paper forms part of a comparative study of the development of environmentalism in Sweden, Denmark and the Netherlands carried out in association with Ron Eyerman and Andrew Jamison of the University of Lund, Sweden.)     

The relationship of race and gender to managers' ratings of promotion potential

The purpose of this paper was to examine the relationship of race and gender to managers' ratings of promotion potential for a sample of 1268 managerial and professional employees. Hierarchial regression analysis showed that controlling for age, education, tenure, salary grade, functional area, and satisfaction with career support, both race and gender were significantly related to promotion potential. Females were rated lower than males, and Blacks and Asians were rated lower than Whites. There were no interaction effects between race and gender.     

A psychological contract perspective on organizational citizenship behavior

This study examined the contribution of the psychological contract framework to understanding organizational citizenship behavior (OCB) using survey data gathered at three measurement points over a three‐year period from 480 public sector employees. Separating perceived contract breach into its two components (perceived employer obligations and inducements), the data suggest that perceived employer obligations explained unique variance in three dimensions of citizenship behavior (helping, advocacy and functional participation) beyond that accounted for by perceived employer inducements. Employees' acceptance of the norm of reciprocity moderated the relationship between employer inducements and the dimensions of advocacy and functional participation. Employees' trust in their employer moderated the relationship between perceived employer obligations and the dimensions of advocacy and functional participation. Contrary to the hypothesis, procedural or interactional justice did not moderate the relationship between employer inducements and OCB. The implications of the findings for psychological contract research are discussed. Copyright © 2002 John Wiley & Sons, Ltd.