A. Martínez Cortizas

Rock coast inheritance: an example from Galicia, northwestern Spain

A shore platform on the western coast of Galicia in northwestern Spain has been inherited from interglacial stages when sea level was similar to today. The wide, gently sloping intertidal platform is backed in places by supratidal rock ledges, and in other places by a steeper and narrower supratidal ramp. The gradient of the intertidal platform is consistent with the relationship between platform gradient and tidal range, but the slope of the ramp is much too high. The abandoned and degraded sea cliff is grass-covered along most of this coast, and the ledges and the ramp, which extend up to several metres above the highest tides, are covered by lichen and, in places, by salt-tolerant plants. Radiocarbon-dated sediments in the cliff, which range up to 36 000 years in age, lie on top of an ancient beach deposit. The former beach, remnants of which are found in situ on the ramp and rock ledges, as well as two caves that are filled with the dated sediments, are probably last interglacial in age. The morphological and sedimentary evidence suggests that the supratidal ramp and ledges were also formed during the last interglacial stage, whereas the wider intertidal platform is probably the product of several older interglacials, when sea level was generally similar to today. A general model is proposed for the inheritance of shore platforms in macro- and microtidal environments. Copyright

Linking changes in atmospheric dust deposition, vegetation change and human activities in northwest Spain during the last 5300 years:

A high-resolution, 5300-yr record of pollen and lithogenic elements (K, Ca, Ti, Rb, Sr, Y, Zr) from an ombrotrophic peat bog located in northwest Spain, reveals that the variations in the fluxes of lithogenic elements supplied to the bog by atmospheric deposition were coupled to the evolution of the vegetation of the area. A strong negative correlation exists between the percentage of tree pollen and the concentration of lithogenic elements. For example, the correlation between total tree pollen and Sr concentrations is - 0.94. The main phases of decline of the deciduous forest occurred during known cultural periods (late Neolithic, the Metal Ages, the Roman Period, the Middle Ages and the Industrial period) suggesting a close link between human activities (fires and forest clearances), changes in the vegetation and soil erosion. The flux of lithogenic elements seems to have increased before a significant variation in pollen is detected, which may indicate that changes in soil erosion are reflected earlier than the changes in vegetation in the bog record. Variations in the composition of the deposited dust reflect impacts that occurred at different spatial scales, with local sources dominant in the late Neolithic, the Metal Ages and the Middle Ages, whilst regional sources are more important in the Roman period and the Industrial Revolution. During the prehistoric period, arboreal pollen percentages recovered to their former levels, suggesting that woodland regenerated following a disturbance phase, but for the last 1400 years no significant recovery took place until afforestation with pines was introduced 200 years ago. While this must be the result of continuous clearances to convert forest into arable land, a cumulative effect on soil degradation must also be implied.

The Posidonia oceanica marine sedimentary record: A Holocene archive of heavy metal pollution

The study of a Posidonia oceanica mat (a peat-like marine sediment) core has provided a record of changes in heavy metal abundances (Fe, Mn, Ni, Cr, Cu, Pb, Cd, Zn, As and Al) since the Mid-Holocene (last 4470yr) in Portlligat Bay (NW Mediterranean). Metal contents were determined in P. oceanica. Both, the concentration records and the results of principal components analysis showed that metal pollution in the studied bay started ca. 2800yr BP and steadily increased until present. The increase in Fe, Cu, Pb, Cd, Zn and As concentrations since ca. 2800yr BP and in particular during Greek (ca. 2680-2465cal BP) and Roman (ca. 2150-1740cal BP) times shows an early anthropogenic pollution rise in the bay, which might be associated with large- and short-scale cultural and technological development. In the last ca. 1000yr the concentrations of heavy metals, mainly derived from anthropogenic activities, have significantly increased (e.g. from ~15 to 47μg g(-1) for Pb, ~23 to 95μg g(-1) for Zn and ~8 to 228μg g(-1) for As). Our study demonstrates for the first time the uniqueness of P. oceanica meadows as long-term archives of abundances, patterns, and trends of heavy metals during the Late Holocene in Mediterranean coastal ecosystems.

Environmental change and social dynamics in the second-third millennium BC in NW Iberia

Analysis of different sediments in NW Spain suggests that a series of abrupt climatic changes occurred between 3500 and 1000 BC. These involved some episodes of cooling and others of drought. There were also changes to the coastline of Galicia. Taken together, these would have offered new opportunities to Copper Age communities who had already embarked on a process of agricultural intensification. The result was a growth of internecine competition.

Distribution of some selected major and trace elements in four Italian soils developed from the deposits of the Gauro and Vico volcanoes

The vertical distribution of 21 elements (K, Ca, Ti, Fe, Mn, Cr, Ni, Cu, Zn, Ga, As, Se, Br, Rb, Sr, Y, Zr, Pb, Th, U, Hg) in four Italian soils derived from volcanic materials has been investigated. Most of the elements, and in particular lithogenic ones, show little enrichment/depletion indicating a low degree of weathering and a great similarity to the parent material. In relative terms, the degree of soil evolution (horizon expression and weathering) and the depletion of the more mobile elements (K, Ca and Sr) seem to increase with increasing rainfall and soil age. Discontinuities in the soil profile due to the accretion of new volcanic material are detectable from the geochemical composition of the horizons. Some metallic elements such as Hg, Pb, Cu, Mn and Zn show enrichment in the organic-rich horizons (O and A), but the intensity of enrichment suggests that, besides biocycling and weathering processes, human activity (soil management, fertilizing and atmospheric pollution) may be significant sources of trace elements.

Characterization and depositional evolution of Hyaena (Crocuta crocuta) coprolites from La Valina Cave (Northwest Spain)

Archaeological excavation of La Valina site, a karstic cave located in northwest Spain, documented a level of human occupation and a later one of carnivores that can be attributed to Upper Plesitocene (35,000 bp) by the 14 C dating obtained from bone samples. Among carnivore remains many coprolites were recovered which, based on morphological and biometrical characteristics, correspond to Crocuta crocuta . Micromorphological analysis of thin sections, mineralogical and palynological analysis let us deduce the deposition period of scats during the year and also the postdepositional changes undergone by coprolites to reach their present state.

Analysis of composition, distribution and origin of hexachlorocyclohexane residues in agricultural soils from NW Spain

Concentrations of the isomers of the organochlorine pesticide hexachlorocyclohexane (HCH) were determined in 252 surface soil samples collected within a sampling network covering agricultural areas in Galicia (NW Spain). The concentration of total HCH (sum of α+β+γ+δ) ranged between 4 and 2305ngg(-)¹ (dry weight), with the α-HCH and γ-HCH isomers predominating (<1-1404ngg(-)¹ and <1-569ngg(-)¹, respectively). The distribution of the pesticide residues was very heterogeneous, with the largest concentrations present in one of the studied areas (the province of A Coruña). The distribution of HCH was not found to be related to any soil property (organic matter, pH, clays, and metals). Multivariate statistical analysis of the data revealed that three populations of samples with a defined composition of HCH, can be related to the source of HCH: technical HCH (α/γ>3), lindane (99% γ-HCH), or both. The existence of a third population consisting almost exclusively of α-HCH suggests that background contamination of anthropogenic origin dates from several decades ago. The detailed analysis of these populations enabled the possible temporal scale of the application of these pesticides to be deduced.

Molecular chemistry by pyrolysis-GC/MS of selected samples of the Penido Vello peat deposit, Galicia, N.W. Spain

Publisher Summary Molecular chemistry reveals significant differences between extracted and non-extractable (residue) peat. In the extracts, lignin and other aromatic fragments, nitrogen-containing moieties are more abundant whereas aliphatics, methyl ketones and lipids are more abundant in the non-extractable fraction. This is not astonishing, since partly oxidized lignin and proteins are hydrophilic and extractable with NaOH, whereas for the extraction of lipids one needs organic solvents. Short-chain straight aliphatics are more abundant in the extractable fraction, and there appears to be a regular decay series of alkanes and alkenes from n -C 28, 28:1 to n -C 10 . One branched alkane that is predominantly present in the extractable fraction is possibly of microbial origin. Some polysaccharide moieties are specifically associated with the extractable fraction and some with the residues. This probably reflects a predominantly microbial origin for the first and predominantly plant-derived for the second, because the plant-derived polysaccharides may still be present in larger molecular units.

Chapter 8 The redox–pH approach to the geochemistry of the Earth's land surface, with application to peatlands

Publisher Summary Redox–pH diagrams given in this chapter provide a concise graphical way in which to depict Earth surface environments in terms of the activities of electrons, the operators involved in the two commonest types of reaction in the weathering zone on land, i.e., redox and acid–base reactions. Peatlands tend to fall on the acid side of the diagrams with ombrotrophic bogs showing least overlap with common soil-forming environments. Minerotrophic mires overlap the field of ombrotrophic bogs under relatively high redox conditions, though with depth they move along a line defined by ferrous–ferric equilibria, to a near-neutral pH. The same kind of equilibria also plays a controlling influence on ambient conditions in mineral soils at the low limit of their pH range.

Solos do topo da Serra São José (Minas Gerais) e suas relações com o paleoclima no Sudeste do Brasil

The diversity of ecosystems in southeastern Brazil can not always be related to edaphic, geomorphologic, or hydrologic factors. Mountain summits, where soils are characterized by common parent material, offer a special environment for studies of soil genesis and dating of cyclic events related to regional climate dynamics. After a detailed investigation of soils from the Sao Jose Hills (Prados - Minas Gerais State, Brazil), two soil profiles (P1 and P2) originated from arenite of the Tiradentes Formation were studied. They are characterized by successive depositions of sandy layers alternated with layers of sand enriched with organic matter. The study site lies 1,350 m above sea level and 350 m above the dominant topographical level of the region. Thirty-three layers with organic matter, alternated with sand layers, were identified in P1. Three layers in P1 (20-30, 70-80, and 100-110 cm depth) with an organic C content of 0,5, 7, and 1 dag kg-1, respectively, present radiocarbon (14C) ages < 40, 180 ± 60, and 350 ± 80 years BP, respectively, and deposition rates of 0.177 cm year-1 at depths between 110 and 170 cm and of 0.357 cm year-1 between 70 and 20 cm layer. In P2, the layers enriched with organic matter are thicker (between 10 and 130 mm), with abrupt discontinuity. They lie between 20-30, 80-90 110-120, and 170-180 cm deep, have a C content of 3, 2.5, 21, and 1.5 dag kg-1, and a 14 C age of 3580 ± 80, 3750 ± 80, 21210 ± 180, and 24060 ± 130 year-1 BP, respectively. Their deposition rates are 0.352 cm year-1 between 20 and 80 cm, 0.002 cm year-1 between 80 and 110 cm and 0.021 cm year-1 at depths between 110 and 170 cm. In both soil profiles, the C/N ratio increases with depth and age. The amount of Ti and Zr, elements of low mobility, are higher in the oldest profile layers, while Cu and Pb are more concentrated in the layers higher in organic matter. A plant fragment (diameter 5 cm, 62 cm long) found at the bottom of P2 dated back to 32220 ± 290 years BP, and is associated with the beginning of this profile formation. The soils at the summit of Sao Jose Hills had its origin in the Tiradentes Formation without contribution of other geologic material. Rain water is the main factor that adds energy to this environmental energy. Therefore, soil formation is related to climate attributes. P1 is a holocenic (Fluvic Entisol) soil, formed by episodic depositions of sand, alternated with sand enriched with organic matter. The formation of P2 (Paleosol) began in the Pleistocene and lasted until the Holocene. The morphology of its buried peat layers is related to oscillations of the water surface of a lake, reflecting drier and more humid climate phases. The assessed radiocarbonic ages are related to Pleistocene and Holocene climate alternations in P2 and holocenic in P1. Profile P2 is an appealing site for palynological studies, where ecotypes that were present in the area beginning in the late Pleistocene can be identified and related to the palaeoclimates.