Bt Horizons Research Articles

산록경사지 토양인 안룡통의 분류 및 생성

Soil Taxonomy 분류체계 변화에 대응하여 산록경사지에 분포하고 있으며, Alfisols로 분류되고 있는 안룡통을 재분류하고, 그 생성을 구명하기 위하여 안룡통 대표단명의 형태적 특성을 조사하고, Soil Taxonomy의 표준 분석방법인 Soil survey laboratory methods manual에 따라서 토양을 분석하여 Laboratory data sheets를 작성하였다. 안룡통은 0~22 cm 깊이에서 ochric 감식표층을 보유하고, 22~120 cm 깊이에서 점토피막과 같은 점토 이동의 근거를 보유하는 arfillic층을 보유하고있다. 그러나 기준 깊이에서의 염기포화도(양이온 합)가 32.3%로 35% 미만이므로 Alfisols이 아나라 Ultisols로 분류되어야 한다. 안룡통은 udic 토양수분상을 보유하고 있으므로 Udults로 분류할 수 있으며, Hapludults의 분류조건을 충족시키고 있다. 또한 Typic 아군의 분류조건을 충족시키므로 Typic Hapludults로 분류할 수 있다. 토성속 제어부위에서의 토성속이 식양질이고, 토양온도상이 mesic 온도상이기 때문에 안룡통은 Fine loamy, mesic family of Ultic Hapludalfs가 아니라 Fine loamy, mesic family of Typic Hapludults로 분류되어야 한다. 안룡통은 산록경사지에 분포하고 있으면서도 안정한 지형에 분포하고 있으므로 토양이 거의 침식되지 않고 새로운 붕적물이 별로 퇴적되지 않기 때문에 오랫동안 토양수의 하향이동에 따른 점토집적작용과 염기용탈작용을 받았다. 그 결과 점토집적층인 argillic층을 보유하는 토양으로 생성 발달되었다. 또한 Alfisols 과 Ulrisols을 구분하는 가장 기본적인 분류기준인 기준깊이에서의 염기포화도 (양이온 합)가 35% 미만으호서 Alfisols이 아니라 강산성 토양인 Ultisols로 발달하였다. This study was conducted to reclassify Anryong series based on the second edition of Soil Taxonomy and to discuss the formation of Anryong series distributed on the mountain foot slope. Morphological properties of typifying pedon of Anryong series were investigated and physico-chemical properties were analyzed according to Soil survey laboratory methods manual. The typifying pedon of Anryong series has brown (7.5YR 4/4) loam Ap horizon (0-22 cm), strong brown (7.5YR 4/6) cobbly clay loam BAt horizon (22-35 cm), strong brown (7.5YR 4/6) cobbly clay loam Bt1 horizon (35-55 cm), reddish brown (5YR 5/4) cobbly clay loam Bt2 horizon (55-82 cm), and brown (7.5YR 5/4) cobbly clay loam Bt3 horizon (82-120 cm). The typifying pedon has an argillic horizon from a depth of 22 to 120 cm and a base saturation (sum of cations) of less than 35% at 125 cm below the upper boundary of the argillic horizon. It can be classified as Ultisol, not as Alfisol. It has udic soil moisture regime, and can be classified as Udult. Also that meets the requirements of Typic Hapludults. It has 18-35% clay at the particle-size control section, and have mesic soil temperature regime. Therefore Anryong series can be classified as fine loamy, mesic family of Typic Hapludults, not as fine loamy, mesic family of Ultic Hapludalfs. Anryong series occur on mountain foot slope positions in colluvial materials derived from acid and intermediate crystalline rocks. They are developed as Ultisols with clay mineral weathering, translocation of clays to accumulate in an argillic horizon, and leaching of base-forming cations from the profile for relatively long periods under humid and temperate climates in Korea.

Differences in initial root development and soil conditions affect establishment of trembling aspen and balsam poplar seedlings

Three studies examined the establishment and early growth of trembling aspen ( Populus tremuloides Michx.) and balsam poplar ( Populus balsamifera L.) from seed. To better understand the differences in initial developmental patterns between both species, we monitored germination and early growth in a washed sand medium with a balanced fertilizer added. Two additional studies used the Ae, Bm, and Bt horizons of a Brunisolic Gray Luvisol soil to test the impact of different soil horizons and conditions (compaction and moisture) on the establishment and early growth of trembling aspen and balsam poplar seedlings. Balsam poplar had faster radicle and leaf area development than trembling aspen and grew similarly in all soil horizons, while trembling aspen only grew well in the Ae horizon, where it outgrew balsam poplar. The superior growth of trembling aspen in the Ae horizon was associated with higher P and organic C relative to the lower horizons. Although germination was lowest on the low-compaction – low-moisture treatment for both species, balsam poplar establishment and early growth were higher than for trembling aspen in all combinations of compaction and moisture. Compared with trembling aspen, the wider establishment niche of balsam poplar is attributed to its faster root development and ability to grow in a range of soil substrates and conditions.

Single element and competitive sorption of copper, zinc and lead onto a Luvisol profile

Abstract The sorption parameters of Cu, Zn and Pb are related to the composition of the different genetic horizons of a Luvisol profile in batch sorption experiments. The affinities of metals towards the soil samples from different horizons followed the same sequence, e.g. Pb≥C>>Zn. By far the highest metal retention was found in the Ck horizon due to the alkaline conditions. It is followed by the A horizon with its high organic matter content, while the lowest sorption capacity was found in the Bt horizon. In the horizons free of carbonate, primarily Pb and Cu were immobilized. The studied soil can be characterized by high amount of organic matter, clay accumulation horizon, as well as calcareous subsoil. This kind of profile development makes soils able to immobilize a significant metal pollution.

Pedogenesis of a catena of the Farmdale–Sangamon Geosol complex in the north central United States

The Farmdale–Sangamon Geosol pedocomplex consists of the Sangamon Geosol and the overlying Farmdale Geosol, which form the most extensive terrestrial record of the last interglacial to glacial transition in the Midwest United States. The geosol complex formed for upwards of 100 ka, extending from the end of MIS 6 through 4 for the Sangamon Geosol, then the Farmdale Geosol for during a brief episode at the end of MIS 3 following slow accumulation and pedogenic modification of eolian silt deposited on top of the Sangamon Geosol. Our study site consists of a buried paleo-hillslope transect that forms a catena, enabling evaluation of slope effects on interglacial-scale soil formation. The Sangamon Geosol is formed in calcareous and illitic glaciogenic sediment. Along the catena the Sangamon Geosol profiles display some morphological changes, namely in terms of colors that we interpret as indicators of differences in drainage. Most thickness and horizonation characteristics are similar all along the transect, with intact upper sola horizons (AE and E horizons) that overlie clay-enriched Bt horizons. The Bt horizons contain abundant clay that exists as illuvial clay coatings, matrix infills, and as mosaic-speckled domains. The clay originated both by in situ weathering and through illuviation from the clay depleted upper sola. Slope does not appear to affect Bt characteristics beyond redder hues of the matrix and clay coatings in the upper slope position. With depth, effects of carbonate leaching and infilling of clay in the matrix decrease and clay coatings are restricted to walls of voids adjacent to aggregates. Clay mineralogy shows illite depletion, but no interstratified kaolinite-expandable minerals, indicating the degree of weathering is not as great as is typical of Sangamon Geosol profiles formed in loess or in glaciogenic sediment of the central Illinois type area. Clay mineralogy is also stratified with depth, coincident with particle size, which probably indicates sorting of layers of illitic dolomite and shale. Variation of horizon and profile characteristics appears to largely be a function of particle size variability and stratification than topographic position in the catena. The influence of hillslope position on soil redistribution during formation of the Sangamon Geosol appears negligible given the uniformity of upper solum horizon thickness and sandy particle size characteristics, so we conclude that a bioturbation and rainwash origin of the upper solum and the texture contrast in these profiles is not the best process model explanation. We suggest that the base-rich nature of these soils led to ecosystem characteristics that discouraged erosion and encouraged infiltration and a lessivage-type origin of the texture contrast. No convincing evidence of MIS 6 through MIS 4 loess occurs at this site. The Farmdale Geosol formed in the Robein Silt, which is Roxana Silt (MIS 3 loess) that was redistributed downslope. The Robein Silt is thicker and finer in the topographic low and indicates the cooler and forested environmental conditions during MIS 3 were conducive to downslope movement of soil and also produced greater differences in drainage-induced soil morphological changes in the Farmdale Geosol.

Application of laser ablation ICP-MS and traditional micromorphological techniques to the study of an Alfisol (Sardinia, Italy) in thin sections: Insights into trace element distribution

An innovative methodological approach is proposed in this study, based on the chemical analysis of different portions of soil horizons (illuvial pedofeatures, pedogenic matrix and skeletal parent rock fragments) by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), associated with traditional micromorphological (optical and scanning electron microscopy) techniques. Validation of the LA-ICP-MS technique provides in situ accurate and reproducible (RSD 13–18%) analysis of low concentration trace elements and rare earth elements (REE) in soil samples (0.001–0.1 ppm). Analyses were carried out on thin sections prepared from undisturbed soil samples, collected from three different Bt (argillic, i.e. clay-illuviated) horizons in an Alfisol from the Muravera area (southeastern Sardinia, Italy). The main aims were (i) to develop and test the reliability of a LA-ICP-MS analytical method on soil thin sections and (ii) to explore the idea that concentrations of trace and rare earth elements in the different portions of a soil profile can be used to investigate their distribution, as a response to pedogenetic processes. The three horizons show similar features, particularly in terms of element concentrations and patterns. By comparing the concentration of REE and other trace elements in the clay coatings, the soil matrix and the skeletal rock fragments in the same horizon, a general enrichment trend is observed from the parent rock to the pedogenic matrix up to the illuvial pedofeatures, suggesting a prominent role of pedogenetic processes in element fractionation and distribution during weathering. In particular, the highest concentration of trace elements (and specifically REE) in clay coatings, which represent the most mobile solid phase in the soil profile, indicates that the former can be used as a reliable indicator of soil weathering if a preliminary assessment of the presence of clay coatings is achieved. In addition, the discontinuous trend of some trace elements among soil features of different horizons is consistent with field evidence of slope dynamics, marked by an erosive and depositional discontinuity along the soil profile.

The role of cation exchange in the sorption of cadmium, copper and lead by soils saturated with magnesium

The displacement of Ca 2+, Mg 2+, K + and Al 3+ from the A and Bw or Bt horizons of two soils developed over serpentinized amphibolites when equilibrated in Cu 2+, Cd 2+ or Pb 2+ solutions was determined, together with the concomitant sorption of the heavy metal. The contributions of Mg 2+ to the effective cation exchange capacities of the A and Bt horizons of the Endoleptic Luvisol were 57% and 94%, respectively, and its contributions to those of the A and Bw horizons of the Mollic Cambisol were 70% and 77%, respectively. In all four horizons, cation exchange, chiefly with Mg 2+ and Ca 2+, was the process chiefly responsible for sorption of Cd 2+, Cu 2+ and Pb 2+. Al 3+ and K + were hardly implicated, especially in the case of Cd 2+.

Clay accumulation and argillic-horizon development as influenced by aeolian deposition vs. local parent material on quartzite and limestone-derived alluvial fans

Where precipitation is ample (udic moisture regimes) and evidence of illuviation clear, argillic-horizon genesis is often easily understood. In drier climates (aridic to ustic), argillic horizons are often interpreted as relict features of the Pleistocene. However, in high montane, western landscapes where climate falls in between these two extremes, the role of aeolian clay inputs vs. in-situ weathering contributing to clay formation is of debate. Two mollisols, one developed in quartzite alluvium (Charkiln series — 3 pedons) and one in limestone alluvium (Troughspring series — one pedon) were examined to determine whether atmospheric dust or local geologies contribute to their development, and whether Bt horizons in both pedons were argillic horizons. We hypothesize that both soils have argillic horizons and that clays are derived from site parent materials. Thin-section specimens of Bt horizons, and sand and silt fraction grains were prepared and examined using a petrographic microscope. Regional dust XRD mineralogic data were compared to XRD rock fragment and soil mineralogic data. Clay films, while seen in all field pedons, were very few and faint in the Troughspring series. Illuviation of clays was evident in thin sections of the Charkiln pedons but not the Troughspring pedon. In the Charkiln series, illuviation is observed as clay-depleted A horizons, clay-accumulating B horizons, clay bridging, clay films on grains and in channels. In the Troughspring pedon, clay-depleted A horizons and clay-accumulating B horizons, very few clay films on grains and some pressure features in packing voids are seen, but grain bridging and coatings on channels are not observed. While local geologies influence soil mineralogy in both series, aeolian dust deposition is as significant and its affect is further enhanced by organic-acid weathering from an overlying pinyon-juniper woodland and the current ustic climate regime. While evidence of an argillic horizon is seen in the Charkiln series, excess Ca in soils is believed to be inhibiting illuviation in the Troughspring series and thus preventing argillic-horizon development.

Vegetative Effect on Surface Structural Development in Highly Impacted Sandy Soils

Whole-tree timber harvesting, which had taken place in 1988, caused massive erosion resulting in exposure of subsurface soil at Fort Benning, GA. Restoration efforts were begun in 1996 using land contouring and two vegetative treatments: (i) a seed mixture of weeping love grass, bahia grass, Bermudagrass, and sericea lespedeza (grass); and (ii) longleaf pine plus the seed mixture (grass + trees). Two additional conditions were included in this study: (iii) volunteer blackberry (berries) and (iv) areas bare of vegetation (bare). Control sites were longleaf pine communities ranging from 60 to 70 years. Specific objectives were (i) to evaluate the effect of vegetation on granular structure formation in subsoil material exposed by erosion and (ii) to evaluate the potential for aggregation to document degree of recovery. Aggregate size distribution was determined by sieving. Resieving after organic matter combustion and clay dispersal was done to determine primary aggregating agents. Granular aggregates at the soil surface of what was previously an E or Bt horizon formed in less than 10 years after the planting of reclamation vegetation. The mean ratio of aggregates bound by organic matter to the total amount of aggregates was greatest in the control (0.87), followed by remediation treatments (for grass, grass + trees, and berries, these were 0.61, 0.46, and 0.37, respectively), and least in the bare treatment (0.26). Remediation treatments, but not volunteer blackberry establishment, significantly enhanced recovery of A-horizon structure relative to bare. Results reflect a shift from blocky or no structure to granular structure in response to remediation. The ratio of organically bound to inorganically bound aggregation is a promising indicator to document recovery of more natural soil surface structure after disturbance.

Complex Permittivity Model for Time Domain Reflectometry Soil Water Content Sensing: II. Calibration

Despite numerous applications of time domain reflectometry (TDR), serious difficulties in estimating accurate soil water contents under field conditions remain, especially in fine‐textured soils. A complex dielectric mixing model was calibrated for fine‐textured soils (24–45% clay) and its accuracy was evaluated and compared with empirical calibrations. The Ap and Bt horizons of two soils were packed into columns and adjusted to volumetric water contents (θ) ranging from air dry to near saturation. Travel time and bulk electrical conductivity (σ0) were measured using TDR at temperatures (T) of 8, 22, and 40°C and using three coaxial cables to obtain a range of input spectrum bandwidths (ωS). Apparent permittivities (Ka) were predicted using the complex permittivity model with measured θ, T, σ0, ωS, and soil bulk density, and fitted to measured Ka by optimizing specific surface area (As), the power‐law exponent (a), and an empirical polarization loss factor. Measured Ka was best approximated using the power‐law dielectric mixing model with a semiempirical effective frequency estimate and a = 0.68. Predicted As increased with increasing clay content, cation exchange capacity, and measured specific surface areas. The two‐parameter power‐law calibration removed temperature bias in θ estimates and reduced the RMSE in θ estimates by an average of 0.006 m3 m−3 compared with an empirical calibration. Empirical models predicted field θ with oscillations of up to 0.022 m3 m−3 in phase with soil temperatures resulting from permittivity temperature dependencies. In contrast, the calibrated dielectric mixing model removed or dampened in‐phase θ fluctuations to <0.004 m3 m−3, which permitted the detection of more subtle changes (<0.02 m3 m−3) in θ.

Geoarchaeology of the Mockingbird Gap (Clovis) site, Jornada del Muerto, New Mexico

AbstractThe Mockingbird Gap site is one of the largest Clovis sites in the western United States, yet it remains poorly known after it was tested in 1966–1968. Surface collecting and mapping of the site revealed a dense accumulation of Clovis lithic debris stretching along Chupadera Draw, which drains into the Jornada del Muerto basin. We conducted archaeological testing and geoarchaeological coring to assess the stratigraphic integrity of the site and gain clues to the paleoenvironmental conditions during the Clovis occupation. The 1966–1968 excavations were in stratified Holocene eolian sand and thus that assemblage was from a disturbed content. An intact Clovis occupation was found elsewhere in the site, embedded in the upper few centimeters of a well‐developed buried Bt horizon formed in eolian sand, representing the regional Clovis landscape. Coring in Chupadera Draw revealed ∼11 m of fill spanning the past ∼11,000 14C years. The stratified deposits provide evidence of flowing and standing water on the floor of the draw during Clovis times, a likely inducement to settlement. © 2009 Wiley Periodicals, Inc.

Late Quaternary paleosols and their paleoenvironmental significance along the Andean piedmont, Eastern Bolivia

The Andean piedmont of eastern Bolivia is situated at the southern margin of Amazonia characterized by an overall humid climate regime with a marked contrast between the rainy and dry seasons. The nearby Subandean foothills deliver abundant sandy sediments to the piedmont, leading to a complex array of sediments and paleosol horizons. Within this setting, the presented study analyzes four profiles of paleosol-sediment-sequences along incised ephemeral streams near Santa Cruz de la Sierra with a focus on past pedogenic variability in the context of the regional late Quaternary geomorphic and environmental evolution. Based on field observations, micromorphological analysis, geochemical and clay mineralogical data five classes of paleosol horizons could be distinguished. The individual paleosol horizons as well as the sediments, in which they developed, were interpreted regarding their paleoenvironmental significance, taking into consideration the various controls on soil formation with particular focus on changes of local environmental conditions through time. Thus, three different pathways of soil formation were established. On the late Quaternary timescale, the results suggest a strong relation between paleoenvironmental conditions (climate, vegetation etc.), soil environment (soil water flow, micro-environment) and the type of paleosol horizons developed in the study area. The formation of “red beds” (Bw horizons) implies very dry soil environments under dominantly dry conditions, which seem to have prevailed in the study area some time before ∼ 18 cal ka BP. Moderately dry but markedly seasonal environmental conditions with a long dry season and strong seasonal contrasts in soil water flow could explain the formation of moderately developed Bwt horizons around ∼ 18 cal ka BP and much of the mid-Holocene. The formation of Bt horizons and/or clay lamellae in relation to intense neoformation of clay and dominant clay illuviation by soil water points to wet conditions similar to today, which have probably prevailed in the study area before ∼ 8 cal ka BP and since ∼ 5 cal ka BP.

Verification of conceptual models of phosphorus, clay, sand and organic carbon distribution in ABt sola

In order to find common distribution and relationship patterns between soil properties a statistic methodology is applied and discussed; the aim is to validate conceptual distribution models of soil constituents. Solum (A and Bt horizonts) data of five profiles located in the Chacopampeana Plain of northwest Argentina were studied; the variables under analysis were the sampling depth (SD) and the content of organic carbon (OC), clay (CLAY), sand (SAND) and total phosphorus (TP). The method was founded on the construction of variables representing the relative variation of contents and sampling depth inside sola (RX variables); RX variables were calculated from the original variables as follows: an “rx” value was defined as the deviation of a value ( x) regarding the profile mean ( x̄) expressed in standard deviation ( S) units of that particular profile. A quadratic regression model of ROC on RSD and RCLAY on RSD explained 97% and 87% of ROC and RCLAY variations respectively, whereas a cubic model of RSAND on RSD explained 90% of RSAND variations; in all models, the determination coefficient ( R 2) was highly significant. These models were consistent with a process of organic matter addition on the top of the soils and a clay eluvial–illuvial process, which originated an eluvial horizon of maximum SAND content, overlying an illuvial CLAY enriched Bt horizon. Regarding TP distribution, the best fitted regression model for RTP on RSD was quadratic, with R 2 0.77. Besides, a multiple regression model for RTP on RCLAY and ROC explained 83% of the observed variability. The aforementioned models were compatible with a combined TP redistribution process: an upward translocation toward the top horizon carried out by biological transport and a downward translocation related to clay eluviation–illuviation; hence, both processes produced a TP impoverishment of the eluvial horizon.

Red Mediterranean Soils: Nature, Properties, and Management of Rhodoxeralfs in Northern Greece

The studied Alfisols were developed on Quaternary calcareous deposits and belong to the great group of Rhodoxeralfs. They occur usually in the meso‐Mediterranean bioclimatic zone and are affected by water deficit during the summer period. They are located mainly on backslope geomorphic surfaces, old terraces, and alluvial fans, and their erodibility is medium to low. Trends of decreased iron content in the deeper soil layers due to severe drainage conditions may be responsible for relatively low values of free iron oxides (Fed). The rather limited variation of Fed may reflect the specific pedogenetic conditions in which red soils were formed. Indices of pedogenesis [Feo/Fed (Feo: amorphous Fe), Fed–Feo, and iron illuviation index of Fed] indicated that the studied pedons are at different stages of development. Redness indices (RI) of Bt horizons in pedons were found in the following decreasing order: P1 = P5 > P4 = P6 > P2 > P3. There were no clear trends of free manganese oxide (Mnd) distribution with depth. The lack of correlation between Mnd and clay or Fed suggested that Mnd oxides do not take part in the co‐illuviation of clay and Fed oxides. Acidity, low content of organic carbon, exchangeable potassium (K+), available phosphorus (P), and water deficit are the main impediments to crop production on these soils. Geomorphological and physicochemical properties suggest that rotation schemes, minimum tillage, liming practices, soil leveling, use of proper irrigation systems, and micronutrient application are among the suggested practices to sustain crop production and mitigate erosion risk.

Cesium and strontium sorption by selected tropical and subtropical soils around nuclear facilities

The dynamics of Cs and Sr sorption by soils, especially in the subtropics and tropics, as influenced by soil components are not fully understood. The rates and capacities of Cs and Sr sorption by selected subtropical and tropical soils in Taiwan were investigated to facilitate our understanding of the transformation and dynamics of Cs and Sr in soils developed under highly weathering intensity. The Langmuir isotherms and kinetic rates of Cs and Sr sorption on the Ap1 and Bt1 horizons of the Long-Tan (Lt) and the A and Bt1 horizons of the Kuan-Shan (Kt), Mao-Lin (Tml) and Chi-Lo (Cl) soils were selected for this study. Air-dried soil (<2 mm) samples were reacted with of 7.5 × 10 −5 to 1.88 × 10 −3 M of CsCl (pH 4.0) or 1.14 × 10 −4 to 2.85 × 10 −3 M of SrCl 2 (pH 4.0) solutions at 25 °C. The sorption maximum capacity ( q m) of Cs by the Ap1 and Bt1 horizons of the Lt soil (62.24 and 70.70 mmol Cs kg −1 soil) were significantly ( p < 0.05) higher than those by the A and Bt1 horizons of the Kt and Cl soils (26.46 and 27.49 mmol Cs kg −1 soil in Kt soil and 34.83 and 29.96 mmol Cs kg −1 soil in Cl soil, respectively), however, the sorption maximum capacity values of the Lt and Tml soils did not show significant differences. The amounts of pyrophosphate extractable Fe (Fe p) were correlated significantly with the Cs and Sr sorption capacities (for Cs sorption, r 2 = 0.97, p < 1.0 × 10 −4; for Sr sorption, r 2 = 0.82, p < 2.0 × 10 −3). The partition coefficient of radiocesium sorbed on soil showed the following order: Cl soil ≫ Kt soil > Tml soil > Lt soil. It was due to clay minerals. The second-order kinetic model was applied to the Cs and Sr sorption data. The rate constant of Cs or Sr sorption on the four soils was substantiality increased with increasing temperature. This is attributable to the availability of more energy for bond breaking and bond formation brought about by the higher temperatures. The rate constant of Cs sorption at 308 K was 1.39–2.09 times higher than that at 278 K in the four soils. The activation energy of Cs and Sr sorbed by the four soils ranged from 7.2 to 16.7 kJ mol −1 and from 15.2 to 22.4 kJ mol −1, respectively. Therefore, the limiting step of the Cs + or Sr 2+ sorption on the soils was diffusion-controlled processes. The reactive components, which are significantly correlated with the Langmuir sorption maxima of Cs and Sr by these soils, substantially influenced their kinetic rates of Cs and Sr sorption. The data indicate that among components of the subtropical and tropical soils studied, short-range ordered sesquioxides especially Al- and Fe-oxides complexed with organics play important roles in influencing their capacity and dynamics of Cs and Sr sorption.

A Mid–Late Quaternary loess–paleosol record in Simmons Farm in southern Illinois, USA

In unglaciated areas of the Mississippi Valley region, the typical full loess–paleosol succession contains the Modern Soil developed in Peoria Silt, weakly developed Farmdale Geosol developed in Roxana Silt, Sangamon Geosol developed in Loveland Silt, and Yarmouth Geosol developed in Crowley's Ridge Silt. Although a fifth loess called the Marianna Silt is reported at one area, the paleosol that separates the Crowley Ridge and Marianna Silts is not well defined. Previous thermoluminescence (TL) and optical stimulated luminescence (OSL) age chronology has suggested multiple phases of Sangamon Geosol developed in Loveland Silt, but clear morphological evidence of polygenetic Sangamon Geosol profiles have not been found. Recently, a thick loess–paleosol sequence has been studied in the middle Mississippi Valley in unglaciated southern Illinois, USA. Soil morphology and analytical results revealed five loesses and associated paleosol units. Two Sangamon Bt horizons were found separated by a thick ACtk horizon, interpreted to indicate two phases of Sangamon Geosol development. This well-preserved loess–paleosol succession provides one of the most complete mid–late Quaternary loess records in the middle Mississippi Valley to date, and is important for studying the stratigraphic framework and paleoclimate and environment changes.

Albeluvisol development with time in loamy marine sediments of southern Norway

This paper reports a study on soil development in loamy marine sediments on both sides of the Oslofjord (Vestfold, Østfold). This region has been subject to steady glacio-isostatic uplift during the whole Holocene. Hence, land surface age continuously increases from the coast inland. Several sea level curves, based on radiocarbon datings, enable estimation of land surface age for all locations. Clay illuviation starts in less than 1650 years. E horizons become lighter with age, but their lower boundary stays around 40 cm for more than 10 000 years. Albeluvic tongues develop between 4600 and 6200 years. Initially, they form along intersections of cracks. As preferential flow and leaching along the cracks continues, the tongues increase in length and width, progressively consuming the prisms between the cracks in the upper Bt horizon. The Fe d/Fe t ratios (weighted means of the upper meter) show a clear linear increase with soil age and may be used for “pedo-dating”, i.e. for estimating the ages of non-dated land surfaces covered with similar sediments. In contrast, the logarithmic decrease of base saturation and pH, with rapid changes in the first time but only very slight changes between 2000 and 10 000 years, makes these parameters unsuitable for “pedo-dating”.

Análise multivariada de Argissolos da faixa atlântica brasileira

A faixa atlântica brasileira possui extrema diversidade ambiental, onde é expressiva a ocorrência de Argissolos, descritos e identifcados em diversos estudos, sem que tenham sido exauridas as possibilidades de interpretações. O objetivo deste estudo foi avaliar, por meio da análise multivariada, as principais diferenças nos atributos físicos e químicos de Argissolos da faixa atlântica brasileira. Foram analisados 91 perfis de solos oriundos de levantamentos pedológicos realizados pelo Projeto RADAMBRASIL, agrupados em três domínios geomorfológicos distintos: Planaltos Soerguidos, Planaltos Rebaixados e Tabuleiros Costeiros, por meio da análise de componentes principais e análise de função discriminante. Para isso, foram selecionadas 14 variáveis para identificar as peculiaridades de cada grupo geomorfológico e suas principais diferenças. A análise dos componentes principais demonstrou que os cinco primeiros componentes respondem por aproximadamente 70 % da variação dos dados. A análise integrada confirmou que os Argissolos dos Planaltos Soerguidos são mais rasos, associando maiores taxas de erosão com menor espessura dos horizontes Bt, e são quimicamente pobres, embora mais rejuvenescidos e rasos. Já os Argissolos nos Planaltos Rebaixados, submetidos a um clima mais seco e, ou, sazonal que os situados nos Planaltos Soerguidos e Tabuleiros Costeiros, mostram-se menos intemperizados e com maior CTC. As análises realizadas (componentes principais e análise discriminante) permitem melhor entender as relações geomorfopedológicas dos Argissolos nos diferentes domínios estudados.

Infiltração da água no solo no sistema pedológico Campus do Arenito, cidade gaúcha, noroeste do estado do Paraná

Considerando a importância do conhecimento do comportamento hídrico das coberturas pedológicas para os estudos de prevenção e contenção dos processos erosivos, o presente trabalho foi realizado em uma vertente com sistema pedológico "Latossolo Vermelho eutrófico/Argissolo Vermelho eutrófico", oriundo do arenito Caiuá, localizado na fazenda experimental da Universidade Estadual de Maringá, município de Cidade Gaúcha, noroeste do Estado do Paraná. Após abordagem morfológica detalhada do sistema pedológico, realizaram-se ensaios de infiltrometria nos principais horizontes diagnósticos e suas respectivas transições em seis perfis de solos dispostos ao longo da vertente. A dinâmica hídrica da cobertura latossólica encontra-se marcada por um comportamento distinto entre a superfície e a subsuperfície. Os horizontes superficiais Ap, AB e, ou, BA exibem ao longo do tempo uma alternância de condições de umidade, ora mais úmidos, ora mais secos, devido à distribuição e intensidade das chuvas. Em profundidade, no horizonte Bw, as condições hídricas dependem da movimentação da água vertical e lateral, não respondendo, portanto, diretamente às variações atmosféricas como na superfície. Na cobertura argissólica, o bloqueio da drenagem vertical ocorre no topo do Bt, gerando acima (horizonte AE) uma zona mais constantemente úmida. De modo geral, os horizontes superficiais dos Argissolos não apresentam as alternâncias de umedecimento e secamento verificadas nos Latossolos; permanecem sempre mais úmidos do que aqueles, em razão dos fluxos hídricos laterais de montante.

Impacts of long‐term waste‐water irrigation on the development of sandy Luvisols: consequences for metal pollutant distributions

SummaryStudies relating macro‐ and microscopic aspects of impacts of long‐term contaminative practices on soils are scarce. We performed such an approach by assessing the fate of metal pollutants in an area close to Paris, where sandy Luvisols were irrigated for 100 years with urban waste water. As a result, these soils display strong accumulation of organic matter, dissolved salts and metal pollutants in surface horizons, but also migration of metals to depth. We examined soil development and metal distribution patterns in two irrigated soils, in comparison with a non‐irrigated reference soil. Soil macromorphological characteristics were studied in the field. Soil micromorphology and micro‐scale metal distributions were both studied in situ in thin sections, the latter by synchrotron X‐ray mapping. Microscopic study focussed on characteristic parts of the Ap and Bt horizons, mainly involved in metal retention. For Ap horizons, both large and diffuse metal concentrations were revealed, mainly associated with organic matter and dissolved components added by irrigation water. For Bt horizons, zinc accumulation was detected on clay‐iron coatings. Our results suggest that with time, a double metal‐filtering capacity has developed in these sandy Luvisols: in the Ap horizon, an anthropogenic filter resulted from input of metal pollutants together with highly reactive organic matter, carbonates and phosphates, thus favouring metal immobilization and limiting migration to depth. In the Bt horizon, the evidence is of a second, natural filter. However, this filtering capacity is endangered by clay destruction due to ferrolysis, as revealed by micromorphology. Ferrolysis, here initiated by intensive irrigation practices, leads to a reduction of the natural filtering potential and an increasing risk of metal transfer towards the groundwater.

Water Flow from Trenches through Different Soils

It is often assumed that soils are homogeneous when designing septic systems or modeling wastewater flow from their trenches. The main objective of this study was to assess water infiltration and movement from the trenches similar to the ones commonly used for on-site wastewater dispersal by septic systems. Four separate experiments, each using a small drainfield with four parallel trenches, were conducted at three sites with different soils. In two experiments the trenches were in the coarse-textured soil above a clayey Bt horizon. In the other two experiments the trenches were in the Bt horizon. For each experiment, 50 L of a solution containing potassium bromide and brilliant blue FCF (as a tracer dye) were applied once a day to each trench for 14 or 15 days. A sampling pit was dug perpendicular to the trenches after the tracer solution application, and the distribution of the tracer dye and Br− around the trenches on the two walls of the pit were assessed. Tracer solution infiltration from the trenche...