Intense Weathering Processes Research Articles

Categorization of Mining Materials for Restoration Projects by Means of Pollution Indices and Bioassays

Sulfide mining wastes may lead to severe environmental and human health risks. This study aims to use geochemical and ecotoxicological indicators for the assessment of the ecological risks of potentially toxic elements (PTEs) in the San Quintín mining group to categorize wastes prior to mining restoration. Ecotoxicity was evaluated using crustacean (Dahpnia magna, Thamnocephalus platyurus) and algae (Raphidocelis subcapitata) bioassays. The geochemical and mineralogical results suggested that the mining residues underwent intense weathering processes, with active processes of acidity generation and metal mobility. Total PTEs concentrations indicated that the mining materials were extremely polluted, with Pb, Zn and Cd geoaccumulation index (Igeo) values higher than 5 in more than 90% of the samples. The pollution load index (PLI) showed average values of 18.1, which classifies them as very highly polluted. The toxicity tests showed a higher toxicity for plants than crustaceans, being the highest values of toxicity related to toxic elements (Pb, Cd and Zn), electrical conductivity and to pH. This paper presents for the first time the combination of indices in the categorization of mining waste prior to its restoration. The combination of them has made it possible to categorize the waste and adapt the restoration and remediation procedures.

Preliminary analysis of rock mass weathering grade using image analysis of CIELAB color space with the validation of Schmidt hammer: A case study

Rock slope instability causes rock slope failure with intense weathering processes in tropical regions. In addition to the various advanced numerical rock slope stability assessment techniques that have been developed thus far, simple evaluation techniques characterizing the rock slope weathering degree based on color changes of the rock surface remain one of the main techniques used by most geologists onto the rock slope stability assessment. The present study proposed a new evaluation method for weathering assessment of the limestone rock slope with computer-assisted image processing technologies to reduce human-induced errors based on a manual characterization process. The color changes of the limestone rock referring the CIELAB color space, which indirectly indicated the differential weathering of the rock mass, were measured in-situ using the FRU colorimeter with a 40 mm aperture. The Schmidt hammer was used to determine the intact rock strength and validate the color changes of the limestone rock to the International Society For Rock Mechanics (ISRM) weathering grade standard. Results indicated that a* and b* correlated strongly with R2 = 0.7404, underscoring the consistency of the CIEL*a*b color space data obtained in situ. The a* and b* correlated strongly with the uniaxial compressive strength result obtained via the rock Schmidt hammer test, with R2 of 0.7058 and 0.7011, respectively. The results were verified with the weathering grades analyzed using image analysis technique. In conclusion, the CIELAB color space is an effective tool in the preliminary assessment of rock mass weathering, particularly for slightly vegetated rock slope outcrops.

The role of geochemical and coal petrographic analyses to determine the depositional sets of Visean coal and shale sequence in Um Thora-Abu Hish area, Central Sinai, Egypt

The Visean time at the Sinai Peninsula is characterized by the deposition of two conformable formations of a siliciclastic (Abu-Thora) resting upon a calcareous (Um-Bogma). The Abu-Thora Formation (Fm) is informally divided into three rock units that comprise a lower and upper sandstone sandwiched with a middle coal and shale sequence. A combination of paleoenvironmental indices and ratios from petrographic and geochemical analyses of the middle sequence succeed to build up the depositional paleoenvironment and may apply to any other coal and shale sequence, especially in coal mine regions. Geochemical analysis reveals that the studied shale strata are not homogenous and can be subdivided into four units from the base to the top. The lower shale unit at the base is 4m in thickness and composed of kaolinite-rich shale (10–77%; nacrite mineral). The second is the middle shale unit of 5.10m in thickness composed of Fe-shale (Fe2O3; 2.04–16.45 wt%). The third is the coal unit of 0.55m in thickness comprising coal seam, and the fourth is the upper shale unit of 6m in thickness composed of wacke (SiO2; 71.63–72.83 wt%). X-ray diffraction (XRD), x-ray fluorescence (XRF) plus mineralogical analyses are applied on the first, second, and fourth units of almost pure shale, whilst the third unit of almost pure coal is subjected to a petrographic analysis instead to illustrate the depositional site and type of vegetation where coal was formed. The palaeoclimatology based on parameters of CIW, C-value, Rb/Sr, and Sr/Cu refers to the deposition of shale initiated at a warm-humid and then to a hot semi-arid climate. The precursor rock of the studied shale is a basaltic and intermediate igneous rock. The shale is of mature components subjected to intense weathering processes based on CIA and ICV of 91.71 and 0.34, respectively. Furthermore, discriminant functions F-1 and F-2 reveal the shale components came also from quartzose sediments that promoted a multi-source origin that was gathered from both preexisting mafic and sedimentary provenances. The accumulation and deposition took place at a marine anoxic shale-carbonate of the active continental margin and oceanic island arc tectonic setting. Maceral composition of the coal unit reveals a depositional setting of a coal-forming mire system that occurred at a paralic aquatic margin setting involving a dominated reed herbaceous vegetation in a hydrological water-logged of the limnic marsh.

Soil and Freshwater Bioassays to Assess Ecotoxicological Impact on Soils Affected by Mining Activities in the Iberian Pyrite Belt.

This study aims to use geochemical, mineralogical, ecotoxicological and biological indicators for a comprehensive assessment of the ecological risks related to the mobility, ecotoxicity and bioavailability of potentially harmful elements in the Lousal mining district. Particularly, toxicity was evaluated using four assays: algae, cytotoxicity assays with HaCaT cell line (dermal), earthworms and Daphnia magna. The geochemical and mineralogical characterization of the studied area shows that the mine wastes underwent intense weathering processes, producing important contamination of the adjacent soils, which also led to the release and mobilization of PHEs into nearby water courses. Total PTE results indicate that the soils affected by mining activities were highly contaminated with As and Cu, while Zn and Pb content ranged from low to very high, depending on the analyzed samples. Cadmium levels were found to be very low in most of the soil samples. The test using Daphnia magna was the most sensitive bioassay, while the Eisenia foetida test was the least sensitive. Except for the LOS07 soil sample, the rest of the soils were classified as “High acute toxicity” and “Very high acute toxicity” for aquatic systems. The results in HACaT cells showed results similar to the ecotoxicological bioassays. The application of biotests, together with geochemical and mineralogical characterization, is a very useful tool to establish the degree of contamination and the environmental risk of potentially harmful elements.

Evaluation of micro-weathering index and weathering grade of diverse geomorphic features of proterozoic terrain applying Schmidt hammer

ABSTRACT The Upper Subarnarekha Kangsabati Interfluve (USKI) belongs to the eastern margin of CGGC, which is part of East Indian Shield. This Proterozoic (1.72–1.87 Ga) terrain had have experienced intensive weathering processes over the long period under different climatic conditions. A total number of 965 Rebound (R) value were collected from eight geomorphic features located in the USKI. In the present study, an attempt has been made to synthesize the history and variation in intensity of weathering using Schmidt hammer (SH). The degree of weathering is calculated using micro-weathering index, which is formulated on Schmidt hammer R-values, collected from deeply weathered (DW) and relatively less weathered (RLW) rock surfaces. The results of the study revealed the different response of diverse types of rock to the geomorphic processes. The weathering grade of each identified geomorphic features has been computed and the results revealed that seven features belong to moderately weathered (grade III) out of eight identified features. The present study is a unique attempt considering multi-cyclic evolution of CGGC to understand the degree of weathering of these studied features, belonging from USKI. This study helps to understand the weathering grade of studied features in quantitative way.

Natural and Anthropic Soil Acidification in the West of Romania

Acidification means the increase in soil acidity due to the natural soil � forming process, frequently in the warm and cool temperate zones, on a wide range of acid rocks consisting of �60% SiO2, primarily as silicate minerals. Typical acid rocks are granites, granodiorites and rhyolites. Subject to intense weathering processes, destruction of clays rich in aluminum occurs in these soils, giving acid conditions. Anthropic acidification consists in the increase in soil acidity due to the action of acid rains or to various farming techniques � application of acid � forming fertilizers.

Monsoonal climate evolution in southern China since 1.2 Ma: New constraints from Fe-oxide records in red earth sediments from the Shengli section, Chengdu Basin

Southern China has experienced a dominantly monsoonal climate since the early Quaternary, owing to the influence of Asian monsoons from several directions during that period. Pedogenic Fe-oxides (hematite and goethite) are regarded as sensitive indicators of monsoonal paleoclimates. To obtain a better understanding of monsoonal climate changes in the subtropical zone of southern China, samples from the Shengli section (Chengdu Basin) were investigated using diffuse reflectance spectroscopy (DRS), high-resolution transmission microscopy (HRTEM), X-ray diffraction (XRD), X-ray fluorescence (XRF), and inductively coupled plasma-mass spectrometry (ICP-MS). TEM results show that both hematite and goethite occur as fine particles with an irregular morphology. Most hematite grains have low crystallinity and nanoporous structure, suggesting that they formed from a ferrihydrite precursor. Uniformity of trace-element and REE distribution patterns, Eu and Ce anomalies, and (La/Yb)N ratios throughout the section suggests that the Shengli deposits were probably well mixed in the source area prior to transport and deposition, and that there has been little change in the source areas of primary materials since 1.2Ma. The high chemical index of alteration (CIA) of the red earth (79–88) reflects strong chemical weathering processes in southern China. Besides, DRS analyses of Fe-oxides show that most red earth samples at Shengli contain more hematite than goethite, which is opposite to typical loess-paleosol profiles from northern China. These results confirm that southern China generally experienced more intense weathering processes than northern China since 1.2Ma.Large fluctuations in major-element oxide concentrations and clay-mineral assemblages in the lower part of the section indicate climatic fluctuations between perennially humid and seasonally humid conditions in the mid-Pleistocene. Monsoonal climate evolution, as proxied by the hematite/(hematite+goethite) [Hm/(Hm+Gt)] ratio, shows a long-term but stepwise cooling and drying pattern in the Chengdu Basin with major transitions at ~1.0, 0.45, and 0.1Ma. These transitions were probably triggered by episodes of tectonic uplift of the Tibetan Plateau and global climate change, with consequent effects on the Asian monsoons. The transitions in our paleoclimate proxy records for southern China match well with shifts in the marine oxygen and carbon isotope records since the mid-Quaternary, providing evidence of strong teleconnections between global and regional climates, terrestrial weathering, and the global carbon cycle.

Hydrothermalism Associeted To Ediacarian Volcanism Of Ait Sawn And Tissouktai (Eastern Anti- Atlas, Morocco)

In the South East of Ouarzazate (south west of the Saghro massif, Anti Atlas) outcrop the geological formations of Ait Sawn and Tissouktai. These, attributed to the Ediacaran (or terminal Neoproterozoic), consist of basic volcanic facies, intermediate and acid intercalated with pyroclastics and epiclastic levels. This set is traversed locally by acidic veins. The rocks studied suffered intense weathering processes marked by the development of secondary minerals which are also formed in the hydrothermal veins and at the expense of the primary magmatic minerals and mesostasis. The main paragenesis of mineralisation consists of hematite, malachite, chalcocite, pyrite, barite, epidote, quartz, chlorite, calcite, albite, sericite and iron oxides. Paleogeography sector is governed by inherited active faults of the Pan African base. Magmatism studied seems to be guided by these tectonic lineaments during the terminal Proterozoic extension. The reactivation of these tectonic structures, after the Cambrian, and probably during the Variscan and / or Atlasic, is certain. Field investigations, supplemented by microscopic and geochemical study, indicate that much of the mineralization associated with volcanic Southwest Massif Saghro, is related to a hydrothermalisme contemporary with the stage of fault reactivation.

Disposal of dredged sediments in tropical soils: ecotoxicological effects on earthworms

The upper limit concentrations of metals established by international legislations for dredged sediment disposal and soil quality do not take into consideration the properties of tropical soils (generally submitted to more intense weathering processes) on metal availability and ecotoxicity. Aiming to perform an evaluation on the suitability of these threshold values in tropical regions, the ecotoxicity of metal-contaminated dredged sediment from the Guanabara Bay (Rio de Janeiro, Brazil) was investigated. Acute and avoidance tests with Eisenia andrei were performed with mixtures of dredged sediment with a ferralsol (0.00, 6.66, 13.12, 19.98, and 33.30 %) and a chernosol (0.00, 6.58, 13.16, 19.74, and 32.90 %). Mercury, lead, nickel, chromium, copper, and zinc concentrations were measured in test mixtures and in tissues of surviving earthworms from the acute tests. While ferralsol test mixtures provoked significant earthworm avoidance response at concentrations ≥13.31 %, the chernosol mixtures showed significant avoidance behavior only at the 19.74 % concentration. The acute tests showed higher toxicity in ferralsol mixtures (LC50 = 9.9 %) compared to chernosol mixtures (LC50 = 16.5 %), and biomass increased at the lowest sediment doses in treatments of both test soils. Most probably, the expansive clay minerals present in chernosol contributed to reduce metal availability in chernosol mixtures, and consequently, the ecotoxicity of these treatments. The bioconcentration factors (BCF) for zinc and copper were lower with increasing concentrations of the dredged sediment, indicating the existence of internal regulating processes. Although the BCF for mercury also decreased with the increasing test concentrations, the known no biological function of this metal in the earthworms metabolism lead to suppose that Hg measured was not present in bioaccumulable forms. BCFs estimated for the other metals were generally higher in the highest dredged sediment doses.

Red soils derived from limestone contain higher amounts of trace elements than those derived from various other parent materials

The concentrations of 48 trace elements (Li, Be, Sc, V, Cr, Co, Ni, Cu, Zn, Ga, As, Br, Rb, Sr, Y, Zr, Nb, Mo, Ag, In, Cd, Sn, Sb, I, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Tl, Pb, Bi, Th and U) in 14 soils derived from limestone, sampled at three sites, are compared with the concentrations in 500 soil samples derived from a variety of other parent materials. The 500 samples were collected from 75 sites nationwide in order to include the wide range of common soil types in Japan. Most analytical results were obtained by inductively coupled plasma mass spectrometry (ICP-MS), but Cr, As, Br, Zr, Sn, and I concentrations were determined by energy dispersive X-ray fluorescence spectrometry (EDXRF), because the acid dissolution techniques employed in this study were found to be incapable of recovering these elements completely. In order to examine the reliability of analyses, the concentrations of many elements were also determined by EDXRF, inductively coupled plasma-atomic emission spectrometry (ICP-AES), and atomic absorption spectrometry (AAS). Box and whisker diagrams (Tukey plots), constructed using log-transformed values of each element, show clearly that geometric means of nearly all the trace elements in soils derived from limestone are higher than those in soils derived from other parent materials. The only exceptions are Sr, Ag and Eu, though statistical analysis (Student’s t-test) shows that the differences for these three elements were not significant at p < 0.05. Similarly, the observed differences of geometric means for Sc, Br and Ba between limestone soils and other types of soils were also not significant at p < 0.05. It can be concluded, therefore, that the concentrations of the above-mentioned 48 trace elements in soils derived from limestone are significantly higher than those in other types of soils, with the exception of Sc, Br, Sr, Ag, and Ba, though it was necessary to exclude 81 soil samples, developed on scoriaceous (basaltic) volcanic ash from Mt. Fuji, as an exceptional group for comparisons of V and Cu, as these soils contain higher levels of these two elements. The above results can be attributed to the gradual accumulation of trace elements in the limestone soils due to the intense weathering processes.

Opening of the Neo-Tethys Ocean and the Pangea B to Pangea A transformation during the Permian

ABSTRACTWe studied the stratigraphy, composition, and paleomagnetic properties of lateritic weathering profiles of Permian age from northern Iran and western Karakoram, Pakistan. A limited set of samples deemed representative yielded stable low-inclination paleomagnetic components carried essentially by hematite of chemical origin isolated in massive, fine-grained, and homogeneous ferricrete facies. These laterites originated at equatorial paleolatitudes characterized by intense weathering processes under warm and humid climatic conditions. Paleomagnetic estimates of paleolatitude from Iran, Karakoram, and north Tibet from this study and the literature, albeit sparse, provide testable constraints on the motion of the Cimmerian terranes as the result of the opening of the Neo-Tethys Ocean along the eastern margin of Gondwana during the Permian. We confirm and help refine previous suggestions that the Cimmerian terranes migrated from southern Gondwanan paleolatitudes in the Early Permian to subequatorial paleolatitudes by the Middle Permian – Early Triassic. As a novel conclusion, we find that timing, rates, and geometry of Cimmerian tectonics are broadly compatible with the transformation of Pangea from an Irvingian B to a Wegenerian A-type configuration with Neo-Tethyan opening taking place contemporaneously essentially in the Permian.

Genesis of kaolinite from Albian sedimentary deposits of the Iberian Range (NE Spain): analysis by XRD, SEM and TEM

AbstractThe kaolinite from Albian sedimentary deposits (Escucha and Utrillas Formations) of the Iberian Range (Spain) have been investigated. This research has shown the presence of different types of kaolinites (detrital and diagenetic) along with micaceous phases in these deposits. Detrital kaolinites show anhedral morphology, low crystallinity and a degree of ordering as well as the presence of interstratified smectite layers. They constitute the matrix of the claystones and siltstones and were probably formed as a consequence of intense weathering processes in the source area during the warm period of the early Cretaceous. Diagenetic kaolinites have been recognized in the sandstones and siltstones, with kaolinite growing between ‘expanded’ mica flakes and vermiform and euhedral kaolinite forming the matrix. They have euhedral morphologies, high crystallinity and a high degree of ordering. They grewin situas a response to incipient diagenesis by K-feldspar dissolution and/or organic acid-rich fluids derived from the maturation of organic matter in shales.

Alteração de plagioclásios dos riodacitos da formação serra geral (JKsg) da região de Piraju - SP

A região de Piraju -- SP é caracterizada geologicamente por apresentar uma grande distribuição de rochas básicas e ácidas da Formação Serra Geral. Os processos e produtos de alteração das rochas básicas são apresentados em muitos trabalhos, mas estudos envolvendo alteração de rochas vulcânicas ácidas são raros. Apresentam-se os resultados de estudos petrológicos, químicos e mineralógicos nas rochas vulcânicas ácidas (riodacitos da Formação Serra Geral), nos produtos de alteração dessas rochas, dando ênfase para a evolução mineralógica dos plagioclásios. Os riodacitos da Fm. Serra Geral (JKsg) possuem em sua composição mineralógica cerca de 60-65% de plagioclásios configurando assim a parte mais importante de sua constituição. O estudo da alteração desses plagioclásios oferece informações importantes em relação a própria alteração da rocha e dos solos relacionados. Resultados obtidos a partir de análises de microscopia óptica, difratometria de raios-X aliados a determinações químicas qualitativas e semi-quantitativas obtidas por microscopia eletrônica de varredura (MEV) permitiram importantes interpretações e conclusões sobre a evolução da alteração nos plagioclásios, a saber: a) por meio de intemperismo não muito intenso, isto é, processo de hidrólise parcial (monossialitização) os cristais de plagioclásio evoluem principalmente para caulinita e secundariamente para mica e haloisita; b) por meio de intemperismo intenso, isto é, processo de hidrólise total (alitização) os cristais de plagioclásio evoluem para gibbsita.

Anthropogenic factors in the geomorphological evolution of the NE and E region of the Loutra Aedipsus area (N. Evia-Hellas)

In the region located northeast and east of the Aedipsos Loutra area landforms of anthopogenic origin have been identified. The formation of these landforms has been attributed to morphodynamic processes that related to human interference; the latter is either straightforward, for example following road-construction, quarries or mines or indirect through human activities such as agriculture, stockbreeding and deforestation. Furthermore, it has been identified that the combined action of natural and human factors has caused the formation of the following landforms (ordered from the older to recent ones): (i) Slopes of moderate gradients and valleys of "U" and "V" shape of natural origin (ii) A vegetation-free land-network with tongue-shaped washed surfaces attributed mainly to indirect anthropogenic influence i.e. stock-breeding (iii) Very fine hydrographie network of Badlands type being the product of direct and indirect human interference (iv) Badlands of pyramid form formed directly by the anthropogenic activities. The landforms associated with stockbreeding are responsible for accelerated erosion and irregular water flow; these factors, in association with the local climatological conditions, operating on the tuffite formations has caused the dvelopement of badlands that destroy the existed valleys through the process of erosion. Pyramid badlands on the other side of the highway, connecting the village Aedipsos and Polilofo are the result of the intensive weathering processes following the construction of the road. Finally, active and inactive badlands exist along the coastal road Loutra Aedipsou-Ilia-Limni, with their formation attributed exclusively to anthropogenic factors. The accelerated erosion, responsible for the above mentioned anthropogenic landforms cause often catastrophic phenomena such as landslides, subsidence etc, which has been observed along the road network of the study area. Therefore, the presence of this type of landforms should be taken under consideration for the construction of the various technical works. Besides, the taking of preventive measures, such as the abstraction of soft (erodible) lithological formations, the construction of slopes with small gradients, the avoidance of banking up etc.

Deposition of sediments during a flood event on seasonally flooded forests of the lower Orinoco River and two of its black-water tributaries, Venezuela

Deposition of suspended sediments andtheir associated nutrients were estimated during theflood event of 1995 in the seasonally flooded forestsof the Mapire and Caura Rivers, two black-watertributaries of lower Orinoco, and on two islands ofthis white-water river. The deposition spanned a widerange from 0.07 kg m−2 in the depositional barforests of the Mapire River to 73.60 kg m−2 onthe flooded forests of the Orinoco Island site calledJarizo. This variation is associated with the dynamicnature of sediment mobilization, transport anddeposition, as well as with the different geomorphicenvironments and erosion processes upstream from thestudy sites. The deposited sediment in all the studyareas was highly quartzitic with a relatively highcontent of kaolinite and goethite. Only in thesediment of the Orinoco Islands was mica (illite)identified in a relatively high proportion. Thesemineralogical results reflect the intense weatheringprocesses in the catchment areas of the study rivers.The chemical composition of the deposited sedimentsshowed a great variability among the different studyareas, which is in part related to the mineralcomposition of the sediments and their particle sizedistribution. The highest concentrations of K, Caand Mg were found on the clay sediments of the Orinocoagricultural island. The total amount of depositednutrients varied over a wide range, which isinfluenced by the amount of deposited sediments. Inthe Jarizo Island site of lower Orinoco were depositedthe largest amount of nutrients. In the floodedforests of the Mapire River, the nutrient contributionby the deposited sediments to the nutrient cycling isrelatively low in the depositional-bar forests andpractically nonexistent in the forests sites onterraces.

Silt: 2–62 μm, 9–4φ

The particles in finer-grained detrital sediments are usually composed of quartz. They fall into two size grades: sand (2 mm–62 μm) and silt (62 μm–2 μm). These size gradings conceal important geological processes since there are geological controls on both the quartz sand and silt populations. Sand nature is largely controlled by geochemical reactions, for example in cooling granite from which it is eventually released by weathering action. The quartz is among the last part of the rock system to solidify and the eutectic-like reaction which occurs ensures that the quartz exists as small crystalline units, each suffering considerable cooling and recrystallisation stresses. Silt is broken quartz, and has traditionally been considered to lack a specific geological control. The situation is confused by the large range of materials that fall into the size category, but there do seem to be distinguishable modes and possibly comminution limits within the 60 μm span. The controls operating in this size range are probably the critical concentration of `Moss' defects in the quartz particles. Moss postulated the formation of specific crystal defects in the quartz formed in granites. These affect sand formation and it is possible that they also control the mode size of silt particles. Within the silt range there may be several usefully definable populations, as Moss proposed for sand. The Quaternary appears to be a silt-rich period due to tectonic and glacial activity, but silt production is apparent throughout the sedimentary record. Very long-term silt producing processes are required. To produce silt in nature, on a large scale, very energetic processes are required. Many processes that are believed to generate silt particles have been listed. However, large-scale production is essentially due to glacial grinding, or to intense weathering processes in high, cold, tectonically active mountain regions. The region of High Asia (of crustal overlap) is a major generator of silt particles. These form the productive alluvial soils of north India, most of the nation of Bangladesh, the loess deposits along the Syr-darya and Amu-darya rivers in Central Asia, and the great loess deposits of North China. Some claims have been made for silt production in hot deserts. Large amounts of very fine aerosolic dust are produced, but in terms of loess-sized particles this is a small-scale process and leads to modest, disputed deposits. The loess deposits around the Sahara usually have smaller mode sizes (e.g., Nigeria) or larger mode sizes (e.g., Libya, Tunisia) than the true Chinese mode at 25 μm. This paper aims to introduce the distinguishing properties of sand and silt, discuss in detail the possible processes of silt formation in relation to the evidence of what is produced, describe the major silt populations, and conclude on the most likely formation process(es). In particular three silt ranges are discussed in relation to the R-size diagram: C, 2–5 μm, D 1, 20–30 μm, and D 2, ∼60 μm. These can represent Canadian quickclay (QQ), Chinese loess and the ideal Loughborough Loess (LL) and North African loess (NAL). It is intended that this paper will put into context the diverse work in the area, and in so doing shed light on what is an often overlooked subject.

Mineralogy and geochemistry of Devonian detrital rocks from the Iberian Range (Spain)

AbstractTwo profiles in Devonian marine deposits have been studied, consisting of pelites, subgreywackes, greywackes and quartzites. Quartz and clay minerals are major components and feldspar and calcite are minor ones. Phyllosilicates in the fine fractions are kaolinite and illite; kaolinite has a high degree of ordering; illite is predominantly of a 1Md polytype, with low Na content and poor crystallinity and has a phengitic composition in greywackes, whereas in pelites it is muscovitic in composition. Both phyllosilicates may be inherited from a source area with intensive weathering processes, although illite may also be a diagenetic phase. These mineral characteristics indicate that the Devonian rocks did not reach the anchizone boundary in their post-depositional evolution.The chemical composition of pelites and subgreywackes reveals a high degree of chemical maturity. Chondrite-normalized REE patterns indicate a higher degree of weathering of these Devonian sediments than of Post-Archaean Australian Shales (PAAS), possibly as a consequence of sedimentary recycling processes. The REE patterns of the Devonian rocks in addition to the high Th/Sc, La/Sc and Th/Co ratios suggest a felsic composition of the primitive source area, probably a K-rich granite.

Changes in the chemical composition of water percolating through the soil profile in a moderately polluted catchment

Throughfall (TF), stemflow (SF), soil solution below the organic layer (SS org ) and at 50 cm depth (SS 50 ), and output with stream water (SW) were measured and analyzed for four years in a moderately polluted forest catchment in southern Poland. The input of water with stemflow was ca. 6 % of input with TF. However, due to higher concentrations of most ions in SF, the input of most elements with SF was from 8% to 9%. Sulphate (SO 4 2- ), chloride (Cl - ) and magnesium (Mg 2+ ) were the only ions steadily increasing in concentrations in water percolating through the soil profile. Nitrogen reached the forest floor mainly as ammonium (NH 4 + ). In the soil organic layer the NH 4 + concentration decreased, while concentrations of nitrate (NO 3 - ) and hydrogen (H + ) increased, probably due to nitrification. For NO 3 - , sodium (Na + ) and calcium (Ca 2+ ), the highest concentrations were found in SS org and SW. This indicates both efficient cycling in the biotic pool of the ecosystem and intensive weathering processes in the mineral soil below the plant rooting zone. The latter was especially pronounced for Mg and Ca. Concentrations of zinc (Zn), lead (Pb) and cadmium (Cd) were the highest in SS org and SS 50 . As this was accompanied by a low pH and constant input of H + , NH 4 + and heavy metal ions to the catchment area, it may pose a serious threat to forest health.

Chemical input/output balance for a moderately polluted forest catchment in southern Poland

A four-year study in a forest catchment exposed to a moderate level of anthropogenic pollution indicated heavy accumulation of hydrogen (H+), manganese (Mn), zinc (Zn), copper (Cu) and lead (Pb) in the ecosystem and phosphorous (P), potassium (K) and cadmium (Cd) to a lesser extent. Nitrogen, which is also accumulated, is leached mainly as NO3−, even though the input is dominated by NH4+. Magnesium (Mg), calcium (Ca) and sodium (Na) are leached from the catchment, presumably due to intensive weathering processes in deeper layers of mineral soil. Chloride ion (Cl−) is also lost from the ecosystem. The output of sulphate (SO42−) with stream water exceeds its input only slightly. Although it appears that the catchment as a whole has a large buffering capacity (average stream water pH=7.43, rainfall pH=4.33), the upper biologically active soil layers are probably more susceptible to acidification and pollution. With constant accumulation of H+ and heavy metal ions this may lead to degradation of forest health.

Changes in chemistry and mineralogy of forest soils by acid rain

The goal of the present study was a qualitative and quantitative determination of chemical and mineralogical changes in forest soils due to acid atmospheric depositions. In the NE/SE Vienna Woods soil samples were taken at 4 depths (0 to 5 cm, 5 to 10 cm, 10 to 20 cm, 20 to 30 cm) in the contaminated infiltration zone of stemflow (S) of 8 beech trees (Fagus sylvatica), strongly influenced by acid atmospheric depositions (soil-pH 2.8 to 3.0) and in their non contaminated reference areas (R) between trees, where acid imput is much smaller (soil-pH 5.0 to 6.0). The results show that intensive weathering processes took place in the contaminated soil areas, which show higher clay and silt contents and smaller aggregates, as well as clay illuviation. Moreover, in the top of the contaminated soil areas higher contents of Ct and St and of the heavy metals Pb, Zn and Cu could be observed, accompanied by extreme low base saturation (expecially of Ca and Mg) and high Al-saturation (50 to 80% of the CEC). These data were confirmed by analysis of the water saturation extract. Moreover, in the contaminated top soils high amounts of Fe-oxides were found, whereas no “secondary” Al-chlorite (due to its instability at pH-values <4.0) could be traced. The desilification process which took place at the same time could be shown through total element analysis. In the clay-fraction strong weathering led to a loss of layer charge and to the genesis of highly expandable three-layer-silicates which could be determined by X-ray diffraction using n-alkylammonium-chloride technics and other chemical treatments.