Questões sobre Classes, Dominação e Conflitos Sociais na Alta Idade Média

Except for a History that is mobilized, nowadays, much more by the supposedly continuities than the changes, the periods of major transitions continue to demand interpretative effort from specialists. It is long the list of those who have been dedicated to the transitional problem between the Antiquity and the Middle Ages, focused on a period of poor and unequally distributed sources, trying to shed light and establish various interpretative means for this phenomenon. Albeit having overcome some of the catastrophic perspectives hindering the pioneer analyses within this context, the current approaches have also eliminated the recognition of both the contradictory manifestations and the social struggles acting as central and fundamental engines of the social transformations within the discussed context. When supported by an adequate theoretical background, documents from the period lead us to a process resulting from contradictions and a scenario of actions and reactions that eventually materialized the conflicts and moved History forward. The transition from the Antiquity to the Middle Ages was encompassed by diverse social antagonist manifestations, which allows us to consider that the arena of disputes were, therefore, that of the society itself.

Questões sobre Classes, Dominação e Conflitos Sociais na Alta Idade Média

Except for a History that is mobilized, nowadays, much more by the supposedly continuities than the changes, the periods of major transitions continue to demand interpretative effort from specialists. It is long the list of those who have been dedicated to the transitional problem between the Antiquity and the Middle Ages, focused on a period of poor and unequally distributed sources, trying to shed light and establish various interpretative means for this phenomenon. Albeit having overcome some of the catastrophic perspectives hindering the pioneer analyses within this context, the current approaches have also eliminated the recognition of both the contradictory manifestations and the social struggles acting as central and fundamental engines of the social transformations within the discussed context. When supported by an adequate theoretical background, documents from the period lead us to a process resulting from contradictions and a scenario of actions and reactions that eventually materialized the conflicts and moved History forward. The transition from the Antiquity to the Middle Ages was encompassed by diverse social antagonist manifestations, which allows us to consider that the arena of disputes were, therefore, that of the society itself.

Questões sobre Classes, Dominação e Conflitos Sociais na Alta Idade Média

Except for a History that is mobilized, nowadays, much more by the supposedly continuities than the changes, the periods of major transitions continue to demand interpretative effort from specialists. It is long the list of those who have been dedicated to the transitional problem between the Antiquity and the Middle Ages, focused on a period of poor and unequally distributed sources, trying to shed light and establish various interpretative means for this phenomenon. Albeit having overcome some of the catastrophic perspectives hindering the pioneer analyses within this context, the current approaches have also eliminated the recognition of both the contradictory manifestations and the social struggles acting as central and fundamental engines of the social transformations within the discussed context. When supported by an adequate theoretical background, documents from the period lead us to a process resulting from contradictions and a scenario of actions and reactions that eventually materialized the conflicts and moved History forward. The transition from the Antiquity to the Middle Ages was encompassed by diverse social antagonist manifestations, which allows us to consider that the arena of disputes were, therefore, that of the society itself.

Analysis and compound of carbon sequestration and serpentinization from the Iberian Margin and the Northern Apennine

Fluid circulation in peridotite-hosted hydrothermal systems influences the incorporation of carbon into the oceanic crust and its long-term storage. At low to moderate temperatures, serpentinization of peridotite produces alkaline fluids that are rich in CH4 and H2. Upon mixing with seawater, these fluids precipitate carbonate, forming an extensive network of calcite veins in the basement rocks, while H2 and CH4 serve as an energy source for microorganisms. Here, we analyzed the carbon geochemistry of two ancient peridotite-hosted hydrothermal systems: 1) ophiolites cropping out in the Northern Apennines, and 2) calcite-veined serpentinites from the Iberian Margin (Ocean Drilling Program (ODP) Legs 149 and 173), and compare them to active peridotite-hosted hydrothermal systems such as the Lost City hydrothermal field (LCHF) on the Atlantis Massif near the Mid-Atlantic Ridge (MAR). Our results show that large amounts of carbonate are formed during serpentinization of mantle rocks exposed on the seafloor (up to 9.6 wt.% C in ophicalcites) and that carbon incorporation decreases with depth. In the Northern Apennine serpentinites, serpentinization temperatures decrease from 240 °C to < 150 °C, while carbonates are formed at temperatures decreasing from ~ 150 °C to < 50 °C. At the Iberian Margin both carbonate formation and serpentinization temperatures are lower than in the Northern Apennines with serpentinization starting at ~ 150 °C, followed by clay alteration at < 100 °C and carbonate formation at < 19-44 °C. Comparison with various active peridotite-hosted hydrothermal systems on the MAR shows that the serpentinites from the Northern Apennines record a thermal evolution similar to that of the basement of the LCHF and that tectonic activity on the Jurassic seafloor, comparable to the present-day processes leading to oceanic core complexes, probably led to formation of fractures and faults, which promoted fluid circulation to greater depth and cooling of the mantle rocks. Thus, our study provides further evidence that the Northern Apennine serpentinites host a paleo-stockwork of a hydrothermal system similar to the basement of the LCHF. Furthermore, we argue that the extent of carbonate uptake is mainly controlled by the presence of fluid pathways. Low serpentinization temperatures promote microbial activity, which leads to enhanced biomass formation and the storage of organic carbon. Organic carbon becomes dominant with increasing depth and is the principal carbon phase at more than 50-100 m depth of the serpentinite basement at the Iberian Margin. We estimate that annually 1.1 to 2.7 × 1012 g C is stored within peridotites exposed to seawater, of which 30-40% is fixed within the uppermost 20-50 m mainly as carbonate. Additionally, we conclude that alteration of oceanic lithosphere is an important factor in the long-term global carbon cycle, having the potential to store carbon for millions of years.

(Table 2) Organochlorine concentrations in polar bears (Ursus maritimus) from East Greenland 1999-2001

Persistent organochlorine (OC) contaminants (PCBs, DDTs, chlordanes (CHLs), dieldrin, hexachlorocyclohexanes (HCHs), chlorobenzenes (CBzs)) were determined in adipose tissue of 92 polar bears (Ursus maritimus) sampled between 1999 and 2001 in central East Greenland (69°00'N to 74°00'N). OC data were presented from subadults (S: females: <5 years and males: <6 years), adult females (F: >=5 years) and adult males (M: >=6 years). Summed chlorobiphenyl (SumCBs) concentrations (41 congeners including co-eluters), SumCHLs and SumDDTs were the dominant classes of OCs. SumCBs concentrations were found to be 6470, 8240 and 9100 ng/g lipid weight (lw) i subadults, adult females and adult males, respectively. The corresponding figures were: 2010 (S), 2220 (F) and 1710 (M) ng/ g lw for SumCHLs and 462 (S), 462 (F) and 559 (M) ng/g lw for SumDDTs. The dominant CB congeners were CB153 (32.3%), CB180 (21.4%), CB170 (12.2%) and CB138 (11.0%). The metabolite p,p'-DDE (88.2%) dominated the SumDDTs, while oxychlordane was the dominant (57.1%) CHL-related compound. Concentrations of SumCBs, SumCBzs, SumDDTs, mirex and dieldrin were highest in adult males, whereas concentrations of SumHCHs were lower than in adult females but not than those in subadults. Adult females had the lowest concentrations of SumCBzs, mirex and dieldrin. Concentrations of SumCHLs were lowest in adult males, intermediate in subadults and highest in adult females. SumCB, SumHCH and SumCHL concentrations showed high seasonal variability in adult females but remained relatively constant in adult males and subadults. In general, the OC levels in females appeared to be highest in March and lowest in January or September. Concentrations of SumCBzs and dieldrin showed seasonal variability in all three groups, with a maximum in March in adult females. SumCBz concentrations in adult males and subadults of both sexes peaked in April-July, and dieldrin concentrations peaked in April-July in subadults, but not until August in adult males. SumDDT concentrations increased from January to a maximum in April-July for subadults and in August for adults. Temporal trends within the last decade were examined by comparing the present data to the concentrations reported in samples from 1990 from the same region. SumCB, p,p'-DDE and SumHCH concentrations in 1999-2001 were 22.1%, 66.3% and 39.3% lower than the 1990 concentrations, respectively. in contrast, SumCHL and dieldrin concentrations showed differences amongst sex and age groups in the temporal trends, where present concentrations are between 24.4% to 69.3% and 27.0% to 69.0% lower, respectively, relative to the 1990 levels. However, power analysis suggested that firm conclusions could not be drawn regarding the general time trend based on these two sampling periods. The range of half-lives of the various OC classes were estimated to lie between 4.5 and 20.6 years depending on the age and sex groups considered.