Impact of Redox Cycles on Manganese, Iron, Cobalt, and Lead in Nodules

International audienceRedox processes are responsible for Fe and Mn segregation as Fe–Mn oxide coatings or nodules. These nodules are also trace element scavengers in soils. Redox processes are of particular importance in seasonally saturated soil containing naturally high concentrations of trace metals. We investigated the dynamics of Fe–Mn nodules and two associated trace elements, Co and Pb, under controlled redox conditions in a column experiment, including five columns fed with mimicked topsoil solution that was elevated in Fe and Mn. The results show that the redox conditions reached 100 mV, which was sufficient to dissolve Mn oxides and release the associated Co, while Pb was readsorbed onto nodule surfaces. The amounts of Mn and Co released into the water were small compared with the quantities stored in the nodules (<0.1% of the initial stock stored in the nodules). The redox conditions were insufficient, however, to allow Fe oxide dissolution. On the contrary, 70 to 90% of the Fe entering the column was fixed onto the nodules. In terms of an environmental threat, these results showed that Pb would not be released from soil during nodule dissolution, whereas Co, which is less toxic, would be released

Dual origins of dairy cattle farming : evidence from a comprehensive survey of European Y-Chromosomal variation

Background - Diversity patterns of livestock species are informative to the history of agriculture and indicate uniqueness of breeds as relevant for conservation. So far, most studies on cattle have focused on mitochondrial and autosomal DNA variation. Previous studies of Y-chromosomal variation, with limited breed panels, identified two Bos taurus (taurine) haplogroups (Y1 and Y2; both composed of several haplotypes) and one Bos indicus (indicine/zebu) haplogroup (Y3), as well as a strong phylogeographic structuring of paternal lineages. Methodology and Principal Findings - Haplogroup data were collected for 2087 animals from 138 breeds. For 111 breeds, these were resolved further by genotyping microsatellites INRA189 (10 alleles) and BM861 (2 alleles). European cattle carry exclusively taurine haplotypes, with the zebu Y-chromosomes having appreciable frequencies in Southwest Asian populations. Y1 is predominant in northern and north-western Europe, but is also observed in several Iberian breeds, as well as in Southwest Asia. A single Y1 haplotype is predominant in north-central Europe and a single Y2 haplotype in central Europe. In contrast, we found both Y1 and Y2 haplotypes in Britain, the Nordic region and Russia, with the highest Y-chromosomal diversity seen in the Iberian Peninsula. Conclusions - We propose that the homogeneous Y1 and Y2 regions reflect founder effects associated with the development and expansion of two groups of dairy cattle, the pied or red breeds from the North Sea and Baltic coasts and the spotted, yellow or brown breeds from Switzerland, respectively. The present Y1-Y2 contrast in central Europe coincides with historic, linguistic, religious and cultural boundaries

Developments and trends in soil science: 100 volumes of Geoderma (1967-2001)

Between September 1967 and March 2001, Geoderma published 100 volumes containing 2079 papers covering 31,637 pages and filling 191 cm of shelf space. No doubt that is a lot of paper, but what is in it? This paper starts with a brief history of the journal and an overview of editors and a geographic breakdown of the editorial board. The contents of the 100 volumes is presented including an overview of the geographic origin of the research and authors, and an analysis of soil science subjects over time. Furthermore, the impact factor and the most frequently papers are discussed. The average length of the papers increased from 12.9 pages in the 1970s to 16.4 pages in the 1990s. Number of authors per paper increased faster so the pages per author have decreased over time. European authors account for about half of the papers but less than 40% of the research was conducted in Europe. The number of authors from North America has increased over the years and about one-fifth of the papers is from research in North America. More than half of the research reported in Geoderma was conducted in the temperate regions, whereas the tropics and subtropics account for about 30% of the papers. In the 1980s, 53% of the papers were descriptive but it decreased to 31% in the 1990s with a higher percentage of papers focussing on methodology. One of the intriguing trends is that 29% of the papers in the 1970s were based on field studies whereas only 18% of the papers in the 1990s were field based. Laboratory studies decreased from 60% in the 1970s to 49% in the 1990s. Over the same period, desk studies increased from 11% to 33% of the published papers. The majority of the papers in Geoderma has had no strong focus and only in recent years papers had an increased focus (i.e. agriculture, environment etc.). There has been a strong increase in soil physics papers whereas the share of soil chemistry steadily declined over time. Typical pedological papers cover about 30% of the journal and little change was found with time, except for the advent of papers in pedometrics. Papers on soil mineralogy have sharply declined from 25% in the 1980s to less than 10% in the 1990s. Over the same period, a doubling in the number of papers on soil and environment occurred. Papers containing information on soil classification increased from 30% in the early 1970s to around 50% in the late 1990s. Alfisols had received most attention followed by Inceptisols. Papers are based on a larger amount of soil samples and in recent years an increasing number of papers are based on existing data. The impact factor of Geoderma has steadily increased since the mid 1970s and in particular in the late 1990s. This review has shown important trends in Geoderma papers that likely reflect some of the major changes that have occurred in soil science as a whole

Spatial trends of genetic variation of domestic ruminants in Europe

The introduction of livestock species in Europe has been followed by various genetic events, which created a complex spatial pattern of genetic differentiation. Spatial principal component (sPCA) analysis and spatial metric multidimensional scaling (sMDS) incorporate geography in multivariate analysis. This method was applied to three microsatellite data sets for 45 goat breeds, 46 sheep breeds, and 101 cattle breeds from Europe, Southwest Asia, and India. The first two sPCA coordinates for goat and cattle, and the first sPCA coordinate of sheep, correspond to the coordinates of ordinary PCA analysis. However, higher sPCA coordinates suggest, for all three species, additional spatial structuring. The goat is the most geographically structured species, followed by cattle. For all three species, the main genetic cline is from southeast to northwest, but other geographic patterns depend on the species. We propose sPCA and sMDS to be useful tools for describing the correlation of genetic variation with geography. © 2010 by the authors; licensee MDPI, Basel, Switzerland