Raimundo Jiménez Ballesta

Pedo-geochemical baseline content levels and soil quality reference values of trace elements in soils from the Mediterranean (Castilla La Mancha, Spain)

To evaluate trace element soil contamination, geochemical baseline contents and reference values need to be established. Pedo-geochemical baseline levels of trace elements in 72 soil samples of 24 soil profiles from the Mediterranean, Castilla La Mancha, are assessed and soil quality reference values are calculated. Reference value contents (in mg kg−1) were: Sc 50.8; V 123.2; Cr 113.4; Co 20.8; Ni 42.6; Cu 27.0; Zn 86.5; Ga 26.7; Ge 1.3; As 16.7; Se 1.4; Br 20.1; Rb 234.7; Sr 1868.4; Y 38.3; Zr 413.1; Nb 18.7; Mo 2.0; Ag 7.8; Cd 4.4; Sn 8.7; Sb 5.7; I 25.4; Cs 14.2; Ba 1049.3; La 348.4; Ce 97.9; Nd 40.1; Sm 10.7; Yb 4.2; Hf 10.0; Ta 4.0; W 5.5; Tl 2.3; Pb 44.2; Bi 2.2; Th 21.6; U 10.3. The contents obtained for some elements are below or close to the detection limit: Co, Ge, Se, Mo, Ag, Cd, Sb, Yb, Hf, Ta, W, Tl and Bi. The element content ranges (the maximum value minus the minimum value) are: Sc 55.0, V 196.0, Cr 346.0, Co 64.4, Ni 188.7, Cu 49.5, Zn 102.3, Ga 28.7, Ge 1.5, As 26.4, Se 0.9, Br 33.0 Rb 432.7, Sr 3372.6, Y 39.8, Zr 523.2, Nb 59.7, Mo 3.9, Ag 10.1, Cd 1.8, Sn 75.2, Sb 9.9, I 68.0, Cs 17.6, Ba 1394.9, La 51.3, Ce 93.5, Nd 52.5, Sm 11.2, Yb 4.2, Hf 11.3, Ta 6.3, W 5.2, Tl 2.1, Pb 96.4, Bi 3.0, Th 24.4, U 16.4 (in mg kg−1). The spatial distribution of the elements was affected mainly by the nature of the bedrock and by pedological processes. The upper limit of expected background variation for each trace element in the soil is documented, as is its range as a criterion for evaluating which sites may require decontamination.

Humus quality after eucalypt reforestations in Asturias (Northern Spain)

The impact on soil properties of recent and ancient reforestations with Eucalyptus globulus Labill. has been studied in Cambisols and Leptosols under temperate semi-oceanic climate in Asturias (Northern Spain). Eucalypt forests showed a high potential of C accumulation in soil, mainly the ancient forest, where the organic matter concentration in the uppermost horizon (up to 415 C g x kg(-1)) was greater than in all neighbouring soil formations (climacic oak forests, up to 84 C g x kg(-1); Podsol under reforested pine forests, 287 C g x kg(-1); and Ulex shrub, 70 C g x kg(-1)). Nevertheless, there was a low concentration of available bases and a very low transformation degree of the organic matter in this eucalypt forest, only comparable to that of the Podsol. In order to analyse the major features of the biogeochemical behaviour of the sites under study, the humus fractions were isolated and the humic acid fraction was studied by derivative visible and infrared spectroscopies. Incubation experiments on whole soil samples were carried out to monitor stability against biodegradation of the organic matter under comparable conditions. In general, soils under eucalypt had a CO(2) production similar to or lower than the control sites, but the soil under the ancient eucalypt forest had a high potential for CO(2) release, similar to that of the neighbouring Podsol, what might be explained by the presence in these soils of high amounts of C accumulated in readily biodegradable forms. However, the mineralisation coefficients (CO(2) released per unit of soil C) indicated that the biodegradability of the soil humus has decreased significantly in the eucalypt-reforested sites, as it could correspond to an effective control of the biogeochemical processes caused by the antimicrobial products from the eucalypt litter. Compared to the original deciduous forests, the lower values of the E(4)/E(6) ratio in the humic acids from eucalypt forests and the lignin signature in the infrared spectra point to humification mechanisms based on the selective preservation of complex macromolecular substances derived from vascular plants. The second derivative of the visible spectra of the humic acid samples under study showed conspicuous valleys, which are ascribed to fungal-derived 4,9-dihydroxyperylene-3,10-quinone pigments. These valleys were in most eucalypt forests significantly shallower than in the original deciduous forests and may also represent an indicator of the impact of introduced vegetation on the structure of the soil microbial system and the mechanisms responsible for the formation of humic acids.

Red palaeosols sequence in a semiarid Mediterranean environment region

In this work we study one of the most palaeopedological sequence formed in Central Spain, which is located on the Pliocene–Pleistocene erosional surface in the Madrid Basin. We also analyse its relationship to erosive and sedimentary Pleistocene events in order to obtain new data for a correct interpretation of the origin and evolution of forms at the top of tabular lands in this site. The geomorphic features and the properties of a sequence of very red palaeosols that developed on this old surface can help us in the understanding of the palaeoclimatic evolution of Central Spain in a Mediterranean climate. They were examined to identify pedologic and climatic changes during the Quaternary. The soil sequence comprises intercalated palaeoargillic and palaeopetrocalcic horizons. The clay minerals are mainly illite, kaolinite, smectite and sepiolite. The alternation of argillic and calcic horizons, limestone debris (cryoclastic colluvions) and aeolian sands suggests succeeding periods of phytostability and phytoinstability (biostasis/rhexistasis). Argillation, rubification and calcium carbonate accumulation were repeated throughout the Pleistocene and it is hypothesised that climatic conditions during numerous stages of this period were not very different from the present conditions.

Natural Enrichment of Trace Elements in Surface Horizons of Calcareous Soils (La Mancha, Spain)

The study of five soil profiles developed on carbonatic sediments of Tertiary Miocene origin has been carried out. The topography of the area was basically flat and the traditional uses of the soils are the cultivation of dry cereals and grapevine. The geochemical characterization of the aforementioned profiles involves a study of the contents of major and trace elements among other pedologic aspects (texture, pH, organic matter, etc.). The results of this study also indicate a superficial enrichment of trace elements due to the leaching of Ca and moderate biological and anthropic activity. We can consider strontium, Sr, as the trace element that characterizes these limy soils (435 mg/kg average content in total soil and 708 mg/kg in the original rock). These contents are similar to the average value in Castilla-La Mancha of 380 mg/kg and are higher than the average in world soils of about 200 mg/kg. High levels of dangerous or pollutant elements (Cd, Hg, Pb, Cu, Zn, or Ni) were not detected. The majority of trace element anomalies are related to calcareous material and the leaching of calcium carbonate (Ca), while the influence of the anthropogenic factor is secondary. Soil quality does not indicate toxicity although surficial enrichment suggests a weak threat from consuming crops.

Critical acid loads for different soils of the Mediterranean environment

Abstract In order to establish strategies to reduce the pollutant emisions, the United Nations Economic Commission for Europe (UNECE) has proposed several methodologies which allows quantification of the Critical Loads (CL) for acid deposition in Europe. Nevertheless, the Steady State Mass Balance and, particularly, the Profile Model — the most common of these methodologies — has been developed for soils with specific acidity problems in Northern Europe and it should be validated for the Mediterranean continental regions. The purpose of this work is to evaluate the Critical Loads of some characteristic pedological ecosystems of the Madrid Community Territory within a north-south transect which also can represents other Mediterranean areas. With some amendments, we consider the Profile model to be applicable.

Pedological Characteristics of Cucumber (Cucumis sativus L) Cropsin Mediterranean Environment (Huete, Spain)

Substrate nutrient and moisture management are two major concerns in the cultivation of Cucumis sativus L cropsinHuete. Entisols (Soil Survey Staff) or Regosols (FAO-UNESCO-ISSS) are the main soil types in this area. These soils are characterized by being moderately deep, they have medium to moderately thick textures and they are on sandy subsoils or sandy loam. The soils are moderately permeable and are susceptible to saturation during periods of prolonged rainfall. The soils are generally fertile are susceptible to mechanized tillage and rarely contain a stony phase.

Aeolian sands and soils of a Wetland Biosphere Reserve: The Tablas de Daimiel

Three soil profiles were characterized from a sandy area situated in a transitional zone in the “Tablas de Daimiel” UNESCO wetland biosphere reserve (TDNP) in the Mancha Plain (Central Spain). The original thickness of the soil layer in this area was as much as 100 cm, but the combined effect of unbalanced cultivation (including irrigation) and an increasingly dry climate has partially eroded their natural properties, almost leading to a desertification process. The main properties of these soils, classified as Xeropsamments (Soil Survey Staff 2006) or Arenosols (IUSS Working Group WRB 2006), are the dominance of sand in the soil matrix, its basic character, and low soil organic matter and carbonate contents. Scanning electron microscopy of the quartz grain surfaces indicated that the superficial textureswere commonly well preserved and characteristic of specific conditions of aeolian formation. Exoscopy revealed a mixture of sub-angular and rounded quartz morphotypes withwell-preserved mechanical impacts on the grain surfaces. These percussion effects are characteristic of aeolian processes and confirmed that mechanical actions were more significant than chemical processes in their pedogenesis.This micromorphological study of the textural sands in the transitional zone of the TDNP revealed that the (red) sands were transported to this area by wind, probably from material of degraded red soils, and deposited on soil horizons previously developed over marls and limestones. The relict character of these materials and specially their susceptibility to degradation should be considered as a priority argument to preserve this area and introduce management measurements to avoid soil erosion.