Behavior of heavy metals from sewage sludge in a Chernozem of the dry belt in Saxony‐Anhalt/Germany

In a small‐plot trial different doses of sewage sludge (equivalent 82‐330 tons of dry matter per hectare) were incorporated in 0—25 cm depth (1982—1985). The aim of the investigations was to study the fate of the heavy metals Zn, Cd, Cu, Ni, Pb, and Cr, to determine their concentration in different soil fractions using a sequential extraction method and to ascertain their uptake by Zea mays L. plants. Eleven years after the last application the metals supplied with the sludge had moved as far as 50 cm in depth. The concentrations of Zn, Cd, Cu, Ni, and Cr in the saturation extract of the sampled soil layers were closely correlated with the concentrations of dissolved organic carbon (DOC). This result suggests that the heavy metal displacement was partly connected with the DOC movement in the soil. Considerable amounts of Zn and Cd coming from sewage sludge were found in the mobile fractions of the soil. Cu, Ni, and Pb were located especially in organic particles, and Cr was obviously bound by Fe‐oxides. Nine years after the last application the binding species of heavy metals were still different compared with those in the untreated soil. The whole withdrawal of heavy metals by plants yielded <1 % of the applied amounts. In the case of Zn the uptake from the sludge amended soil decreased during the experimental period. No similar tendency was observed for the other elements. In any case their annual variations of uptake exceeded the effect of sludge application.     

The Vjosa River corridor: a model of natural hydro-morphodynamics and a hotspot of highly threatened ecosystems of European significance

Landscape Ecology - Large near-natural rivers have become rare in Europe, a fact reflected in the high conservation status of many riverine ecosystems. While the Balkan still harbors several intact...     

Food justice or food sovereignty? Understanding the rise of urban food movements in the USA

As world food and fuel prices threaten expanding urban populations, there is greater need for the urban poor to have access and claims over how and where food is produced and distributed. This is especially the case in marginalized urban settings where high proportions of the population are food insecure. The global movement for food sovereignty has been one attempt to reclaim rights and participation in the food system and challenge corporate food regimes. However, given its origins from the peasant farmers' movement, La Via Campesina, food sovereignty is often considered a rural issue when increasingly its demands for fair food systems are urban in nature. Through interviews with scholars, urban food activists, non-governmental and grassroots organizations in Oakland and New Orleans in the United States of America, we examine the extent to which food sovereignty has become embedded as a concept, strategy and practice. We consider food sovereignty alongside other dominant US social movements such as food justice, and find that while many organizations do not use the language of food sovereignty explicitly, the motives behind urban food activism are similar across movements as local actors draw on elements of each in practice. Overall, however, because of the different histories, geographic contexts, and relations to state and capital, food justice and food sovereignty differ as strategies and approaches. We conclude that the US urban food sovereignty movement is limited by neoliberal structural contexts that dampen its approach and radical framework. Similarly, we see restrictions on urban food justice movements that are also operating within a broader framework of market neoliberalism. However, we find that food justice was reported as an approach more aligned with the socio-historical context in both cities, due to its origins in broader class and race struggles.     

Adaptive coding of reward value by dopamine neurons

It is important for animals to estimate the value of rewards as accurately as possible. Because the number of potential reward values is very large, it is necessary that the brain's limited resources be allocated so as to discriminate better among more likely reward outcomes at the expense of less likely outcomes. We found that midbrain dopamine neurons rapidly adapted to the information provided by reward-predicting stimuli. Responses shifted relative to the expected reward value, and the gain adjusted to the variance of reward value. In this way, dopamine neurons maintained their reward sensitivity over a large range of reward values.     

Changes in collembolan species composition in Eastern German mine sites over fifty years of primary succession

Brown-coal opencast mining provides a virgin soil substratum at a scale of square kilometres that is open to primary succession. Focusing on this process, we investigated changes in collembolan species composition in a long-term study that lasted almost 40 years (1960–1998) at mine sites, afforested with deciduous trees. The geological overburden, which characterises the soil quality, consisted mainly of Pleistocene and Tertiary sands, interspersed with lignite and dark Tertiary loam and clay.

According to their appearance during the primary succession, we established eight colonising groups, representing 90 of 113 species found. Results from soil samples as well as from pitfall traps were taken into account for the definition of the groups. Thus, edaphic and epedaphic life forms were equally regarded. Generally, “initial”, “pioneer” and “woodland” groups were discernible.

Largest changes in species composition occurred during the first ten years, as indicated by decreasing species turnover rates and increasing alpha diversity. A comparison with other (essentially shorter) studies on Collembola of mine sites (12 in Europe, 3 in other parts of the world) showed that some pioneer species are cosmopolitan whilst others seem to be regionally specific. Important events in the ecosystem development of mine sites, as indicated by the collembolan community, are the first occurrence of other humiphagous soil animal groups, especially that of earthworms, followed by a disappearance of the ectohumus layer. The similarity between collembolan communities of mine sites and of adjacent native woodlands is greatest ten years after afforestation. Fifty years after afforestation, the collembolan community still differed markedly from that of native stands. Thus, a gradual development of the mine site collembolan communities to a comparable native woodland community is not evident from the data.     

Einige Gedanken zuVavilovs Gesetz der homologen Reihen und zu den Ursachen homologer genetischer Variationen aus wissenschaftstheoretischer Sicht

Zusammenfassung Es wird die nach wie vor bestehende Gültigkeit des Gesetzes der homologen Reihen anhand von Ergebnissen der Zoologie und der konventionellen Pflanzenzüchtung dargestellt. Der Stand der Diskussionen über die Ursachen homologer Mutationen wird erörtert. Es wird der innere sachliche Zusammenhang des Gesetzes der homologen Reihen mit der Theorie der Gen- oder Mannigfaltigkeitszentren deutlich gemacht und Gültigkeit und Grenzen des Gesetzes der homologen Reihen im Lichte der sich abzeichnenden Ergebnisse und Aussichten der Gentechnologie diskutiert. Die erkenntnistheoretische Bedeutung des Gesetzes der homologen Reihen für Genetik und Züchtung wird mehrfach sichtbar gemacht.Im Unterschied zuVavilovs Genzentrentheorie, die in den letzten Jahren wiederholt kontrovers und kritisch diskutiert worden ist (Harlan 1971,Lehmann 1984), findet das vonVavilov im Juni 1920 auf dem III. Allrussischen Kongreß der Züchter erstmals formulierte und 1922 erstmals publizierte Gesetz der homologen Reihen (law of homologous series in variation) (Vavilov 1922) bis in die jüngste Zeit im großen und ganzen ungeteilte Zustimmung. Die Züchtung hat auf seiner Grundlage immer wieder erfolgreich gearbeitet, was die Gültigkeit der vonVavilov erkannten allgemeinen gesetzmäßigen Zusammenhänge bestätigt. AlsVavilov im Juni 1920 in Saratov das Gesetz der homologen Reihen erstmals öffentlich vortrug, wurde er enthusiastisch alsMendelejev der Biologie bezeichnet (Wessel 1986). Und in der Tat ermöglichte das Gesetz ähnlich dem Periodensystem der chemischen Elemente auf Grund bekannter Zusammenhänge die Voraussage der Existenz noch unbekannter Formen, die dann tatsächlich gefunden wurden. Der seinerzeit aufsehenerregende Erfolg der vonBaur auf der Grundlage des Gesetzes der homologen Reihen und auf der Grundlage derAntirrhinum-Forschung initiierten Süßlupinenzüchtung brachteVavilovs Gesetz allgemeine Anerkennung. Bekannt ist die Gültigkeit des Gesetzes nicht nur für Leguminosen, sondern auch für Gramineen und Cruciferen. Neben morphologischen Merkmalen gibt es homologe Wiederholungen auch bei physiologischen Merkmalen wie Variabilität, Widerstandsfähigkeit gegen niedere Temperaturen und Krankheiten, Länge der Vegetationszeit, photoperiodisches Reaktionsvermögen, Gehalt an primären Pflanzenstoffen (Kohlenhydrate, Eiweiße, Fette) und an sekundären Pflanzeninhaltsstoffen (Alkaloide, Glycoside, Gerbstoffe).

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Vavilov's law of homologous series and the causes of homologous genetic variations — theoretical aspects

Summary The continuous validity of the law of homologous series is proved by the results of zoology and conventional plant breeding. An outline is given of the present state of discussion on the causes of homologous mutations. The relationship between the law of homologous series and the theory of gene centres (theory of genetic diversity) is shown. Validity and limits of the law of homologous series are discussed in the light of results and prospects of modern genetic engineering. The theoretical significance of the law of homologous series for genetics and plant breeding is illustrated by several examples.

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Platelet-derived serotonin mediates liver regeneration

The liver can regenerate its volume after major tissue loss. In a mouse model of liver regeneration, thrombocytopenia, or impaired platelet activity resulted in the failure to initiate cellular proliferation in the liver. Platelets are major carriers of serotonin in the blood. In thrombocytopenic mice, a serotonin agonist reconstituted liver proliferation. The expression of 5-HT2A and 2B subtype serotonin receptors in the liver increased after hepatectomy. Antagonists of 5-HT2A and 2B receptors inhibited liver regeneration. Liver regeneration was also blunted in mice lacking tryptophan hydroxylase 1, which is the rate-limiting enzyme for the synthesis of peripheral serotonin. This failure of regeneration was rescued by reloading serotonin-free platelets with a serotonin precursor molecule. These results suggest that platelet-derived serotonin is involved in the initiation of liver regeneration.     

Application of an Air Ionization Device Using an Atmospheric Pressure Corona Discharge Process for Water Purification

Pesticides presently being discharged into the aquatic environment are not only toxic but also only partially biodegradable, they are not easily removed by conventional water treatment plants. Air ionization devices using an atmospheric pressure corona discharge process show great promise in improving degradation of chemical and biological contaminants in water purification plants. In order to assess the effectiveness of this air ionization apparatus, laboratory scale degradation experiments were carried out systematically in a bubble column reactor containing a variety of pesticides such as triazines, carbamates, phenyl urea derivates and chlorophenols relative to the addition of humic acid and inorganic chemicals as well as to pH variation. Chemical oxygen demand (COD) decreased with air ionization treatment and the rate of the biological oxygen demand related to this (BOD/COD) showed improved pesticide biodegradability. Changes in water toxicity were monitored by Daphnia- and Luminescence Bacteria tests. This novel water treatment process is shown to be a potent oxidation technique for persistent organic pollutants such as pesticides.