Effects of lanthanum and lanthanum-modified clay on growth, survival and reproduction of Daphnia magna

The novel lanthanum-modified clay water treatment technology (Phoslock^®) seems very promising in remediation of eutrophied waters. Phoslock^® is highly efficient in stripping dissolved phosphorous from the water column and in intercepting phosphorous released from the sediments. The active phosphorous-sorbent in Phoslock^® is the Rare Earth Element lanthanum. A leachate experiment revealed that lanthanum could be released from the clay, but only in minute quantities of 0.13-2.13 μg l⁻¹ for a worst-case Phoslock^® dosage of 250 mg l⁻¹. A life-history experiment with the zooplankton grazer Daphnia magna revealed that lanthanum, up to the 1000 μg l⁻¹ tested, had no toxic effect on the animals, but only in medium without phosphorous. In the presence of phosphorous, rhabdophane (LaPO₄ · nH₂O) formation resulted in significant precipitation of the food algae and consequently affected life-history traits. With increasing amounts of lanthanum, in the presence of phosphate, animals remained smaller, matured later, and reproduced less, resulting in lower population growth rates. Growth rates were not affected at 33 μg La l⁻¹, but were 6% and 7% lower at 100 and 330 μg l⁻¹, respectively, and 20% lower at 1000 μg l⁻¹. A juvenile growth assay with Phoslock^® tested in the range 0-5000 mg l⁻¹, yielded EC₅₀ (NOEC) values of 871 (100) and 1557 (500) mg Phoslock^® l⁻¹ for weight and length based growth rates, respectively. The results of this study show that no major detrimental effects on Daphnia are to be expected from Phoslock^® or its active ingredient lanthanum when applied in eutrophication control.     

Review of Directions in Soviet social psychology.

Reviews the book, Directions in Soviet social psychology, edited by Lloyd H. Strickland (1984). This book is about collectives: not just any organized group that might be so called in the Soviet Union, but groups that have attained (or are in the process of attaining) a genuine collectivity, internal cohesiveness, or solidarity. The editor has put together ten chapters, each by one or more of the Soviet Union's most prominent social psychologists. The contributions were written with a view to giving Western psychologists--in as nonpolemic a manner as possible--an understanding of the various problem areas in Soviet social psychology, of where they have come from historically, of what Soviet psychologists see as the major issues, of how they do research, and of some of their findings and conclusions. The contributions appear diverse. They deal with subjects as varied as the self-concept, communication, cognitive processes, person perception, self-discipline, management, and industrial psychology. Beneath the diversity, however, emerges a common preoccupation with the collective, its development and dynamics. This unity of underlying concern, in turn, lends the book a remarkable coherence. The book is, however, not without its difficulties. The main one is a certain opacity characteristic of English translations of Russian scientific works. The editor acknowledges and discusses this problem in an afterword. He has also provided the reader with an informative preface that explains how the book came about, and each chapter is headed by a brief but helpful introduction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)