Cm Of Profile Research Articles

Micromorphology and environmental behavior of oxide deposit layers in sulfide-rich tailings in Tongling, Anhui Province, China

Sulfide-rich tailings produced by mineral processing are prone to oxidation and cause many pollution problems in the surrounding environment; therefore, this issue has become a focus of attention. The Tongling Shuimuchong tailings reservoir contains a large amount of sulfide minerals, especially pyrrhotite and pyrite. This reservoir features obvious oxidation in the surface layer, and the slab is very hard. Mineralogical and environmental geochemical analyses were performed on tailings with different degrees of oxidation in the Shuimuchong tailings reservoir to investigate the influence of the formation of the hard oxidized layer on environmental pollution in the tailings pond. The samples were first subjected to particle-size analysis. The shallow tailings were mainly composed of medium particle; the proportions of coarse particle and fine tailings particles were equal; and the proportions of clay and silt were less than those of the other size fractions. Mineralogical analysis showed that pyrrhotite and pyrite were replaced by residual structures in the oxide layer. The secondary minerals goethite, hematite and jarosite were attached to the edges and fractures of sulfide minerals. The samples were geochemically analyzed to determine the total concentrations of 5 elements, the pH and the major anions. The maximum SO42− concentrations of 33,970 and 32,749 mg/kg were observed at a depth of 40 cm in profiles 1 and 2, respectively. Metal sulfide mineral oxidation in the tailings lowered the pH of the materials to values less than 4. The concentration of HCO3− (122–635 mg/kg) in the tailings samples was very low, and the concentration of CO32− was zero. As (53.2–133.7 mg/kg), Pb (24.2–307.5 mg/kg) and Hg (0.03–0.06 mg/kg) were concentrated in the highly oxidized layer at the surface; the Cd content (0.23–10.5 mg/kg) increased with decreasing oxidation degree of the tailings; and the Cr content (38.0–54.9 mg/kg) fluctuated around a certain value.

Increasing Soil Water Retention with Native‐Sourced Mulch Improves Seedling Establishment in Postmine Mediterranean Sandy Soils

AbstractSeasonal drought and heavily impeded soils reduce restoration success in Mediterranean‐type postmine soils, where up to 90% seedling mortality has been observed after 2 years. To alleviate these barriers, amendments were incorporated into the soil profile of a freshly mined sand quarry. Within the quarry, three 223 m2 replicate sites contained two substrate amendments: 12% v/v native‐sourced mulch or gravel incorporated within the top 50 cm of the soil profile. Three remnant sites provided a “natural” reference system. Seeds of two autochthonous trees, Banksia attenuata (R.Br.) and B. menziesii (R.Br.) were sown across all treatments. Soil impedance, moisture, and seedling stomatal conductance were monitored for 2 years, at which point seedlings were excavated, and nutrient concentration, root morphology, and soil chemical properties were measured. Roots in all restoration treatments were restricted to the top 40 cm of the profile due to increases in soil impedance, regardless of amendment, compared to >70 cm in the natural system. Seedling mortality was greatest after the second summer in the control and inorganic amendment treatments, with stomatal conductance indicating severe drought stress. Survival in the organic treatment was 24–42% greater than the control, with higher soil moisture and stomatal conductance rates 2.5 times that of the control. The increased soil water retention by a native‐sourced mulch was shown to improve postmine restoration success for these native trees.

Assessing plankton and other particles in situ with the SOLOPC

We combined a Sounding Oceanographic Lagrangian Observer float with a Laser Optical Plankton Counter (LOPC) and a fluorometer to make an autonomous biological profiler, the SOLOPC. The instrument senses plankton and other particles over a size range of 100 µm to 1 cm in profiles to 300 m in depth and sends data ashore via satellite. Objects sensed by the LOPC include aggregates and zooplankton, the larger of which can be distinguished from one another by their transparency. We hypothesized that the diel production of particles and their loss by sinking and grazing are reflected in the change of the particle distribution. We present data from four deployments of the SOLOPC off California. Particle volume was maximal at the base of the surface mixed layer and correlated with chlorophyll a fluorescence. In a 3‐d deployment in 2005, particle volume was greatest in the early evening and smallest in the morning, and average particle size increased with depth. Eigenvector analysis of the particle volume distribution as a function of diameter for each of the deployments yielded size peaks characteristic of planktonic crustaceans. Ship‐based measurements showed that the abundance of opaque particles of 1.1‐1.7 mm equivalent spherical diameter was positively correlated with copepods of this size and simultaneously collected in nets. This relationship was used with SOLOPC data to estimate the distribution of large copepods, which were most abundant beneath the depth of maximal particle flux, estimated from particle size and published sinking rates. Our data are consistent with a model with diel production of particles and their loss by sinking and grazing.

Environmental and vegetation relationships of the Artemisia tridentata spp. wyomingensis alliance

The Artemisia tridentata spp. wyomingensis (Beetle & A. Young) S.L. Welsh alliance is the most extensive of the big sagebrush complex in the Intermountain West and is characterized by a wide range of environments and vegetation heterogeneity. The purpose of this study was to identify environmental factors driving variation in plant species composition and determine the potential for using environmental factors to explain vegetation characteristics of the A. tridentata spp. wyomingensis alliance. Seventeen environmental factors and seven vegetation response variables were measured on 107 relatively undisturbed, late seral A. tridentata spp. wyomingensis sites across southeastern Oregon and northern Nevada. Non-metric multidimensional scaling (NMS) was used to identify environmental factors correlated with plant species composition as indexed by canopy cover. Stepwise multiple linear regressions were used to develop models correlating plant cover and structural characteristics with environmental factors. Vegetation composition variation appears to be driven by soil characteristics. Canopy cover of perennial grasses and forbs was moderately correlated with direct incident radiation and soil characteristics, particularly soil texture in the upper 15 cm of the profile. Total herbaceous cover variation was better explained by environmental factors (soil water-holding capacity, incident radiation, depth to Bt horizon, and percent sand in the upper 15 cm of the soil profile) ( P<0.0001, R 2=0.52) than any other vegetation characteristic. Vegetation structural characteristics (e.g. sagebrush height, canopy volume and canopy cover, density, and plant visual obstruction) exhibited weak or no relationships with measured environmental variables. Limited correlation among environmental factors and some vegetation characteristics was likely due to the large ecological amplitudes and ecotypic variations expressed by many of the plant species in the sagebrush steppe. This study expands our understanding of the A. tridentata spp. wyomingensis alliance and elucidates the complexity of environmental–vegetation relationships.

Soil formation in Wright Valley, Antarctica since the late Neogene

We investigated over 180 soil profiles on 15 drift units ranging from Recent to Pliocene or older in age in Wright Valley, Antarctica. The drifts originate from (1) post-valley cutting by an advance of the East Antarctic Ice Sheet, (2) advances of the Wright Lower Glacier from grounding of ice in the Ross Embayment, and (3) advance of alpine glaciers along the south valley wall. Holocene and LGM soils lack staining (from oxidation of iron-bearing minerals) and visible salts, contain ice or ice-cemented permafrost in the upper 0.5 m, and are classified as Glacic or Typic Haploturbels. Other soils of late Quaternary age are stained to < 10 cm, contain ice-cemented permafrost in the upper 0.5 m, have stage 1 salts (encrustations beneath surface clasts) and < 1000 mg salts cm − 2 in the upper 70 cm of profile, and are classified as Typic Haploturbels. Soils of mid-late Quaternary age are stained to 20 cm, have ice-cemented permafrost at depths in excess of 1 m and stage 2 salts (flecks and patches covering < 20% of the profile face), contain 1000–1700 mg salts cm − 2 , and are classified as Typic Anhyorthels. Soils of early Quaternary to late Pliocene age are oxidized to depths > 30 cm, have stage 3 salts (flecks and patches covering > 20% of the profile face), contain 4000–4200 mg salts cm − 2 , and are classified as Salic Anhyorthels. Soils of Pliocene age are deeply oxidized (> 50 cm), have stage 5–6 salts (strongly cemented or indurated salt pans), contain 5000–7000 mg salts cm − 2 , and are classified as Petrosalic Anhyorthels. Soils of early Pliocene or older age do not show the degree of development of younger soils because they are derived from Peleus till which contains highly erosive, fine-sandy, quartz-rich rock. Our data question the notion of high-level Antarctic lakes occupying most of the valley during the LGM and early Holocene.

Influence of repeated prescribed burning on the soil fungal community in an eastern Australian wet sclerophyll forest

A long-term prescribed burning experiment, incorporating replicated plots that receive burning biennially (2 yr burn) or quadrennially (4 yr burn) and unburned controls, has been maintained in a wet sclerophyll forest at Peachester, Queensland, Australia since 1972. In 2003 we extracted DNA from soil collected from the experimental plots and investigated the influence of the burning on the soil fungal community by comparing denaturing gradient gel electrophoresis (DGGE) profiles of PCR-amplified partial rDNA internal transcribed spacer regions (ITS1). Canonical analysis of principal coordinates (CAP) of the DGGE profiles of the upper 10 cm of the soil profile grouped the data strongly according to treatment, indicating that both burning regimes significantly altered fungal community structure compared to the unburned controls. In contrast, no obvious trend was observed for soil from a depth of 10–20 cm of the profile. Sequencing of selected DGGE bands found no obvious patterns of presence/absence of taxonomic groups between the treatments. Analysis of soil nitrogen and carbon by mass spectrometry indicated that total soil C and N, along with both gross and net N mineralisation, were significantly lower in 2 yr plots compared to control and 4 yr plots.

Comportamento físico-hídrico de um podzólico vermelho-amarelo câmbico fase terraço sob diferentes sistemas de manejo

O estudo foi desenvolvido no município de Viçosa, MG, na fazenda Fundão, pertencente ao câmpus da Universidade Federal de Viçosa (UFV), com o fim de verificar o comportamento físico- hídrico de um Podzólico Vermelho-Amarelo câmbico fase terraço, sob diferentes sistemas de manejo. Foi utilizado delineamento experimental em blocos ao acaso, com cinco tratamentos e quatro repetições. Os tratamentos foram: 1 - arado de aiveca; 2 - arado de discos; 3 - grade pesada; 4 - plantio direto; 5 - testemunha, com as parcelas mantidas em pousio. Os parâmetros avaliados foram: teores de matéria orgânica; granulometria; densidade do solo; densidade de partículas; porosidade total, macroporosidade, microporosidade, agregados e curva de retenção da água no solo. Pode-se concluir que: o uso da grade pesada reduz os teores de matéria orgânica na camada de 0-15 cm; a utilização da grade pesada acarreta adensamento da camada superficial; o revolvimento do solo ocasiona maior macroporosidade; o sistema plantio direto proporciona menor desagregação do solo; o sistema plantio direto garante maior retenção de água.

Effect of surface application of urea, ammonium-sulfate and lime on exchangeable cation distribution in an inceptisol in humid tropical Queensland

The effect of two sources of N (urea and ammonium sulfate) on the leaching of exchangeable cations in an Inceptisol was examined in the field over a 6 week period. During this time, artificial rainfall (60, 80 and 90 mm) was applied on three occasions to enhance the rate of leaching of exchangeable cations. This was assessed by taking soil samples prior to, and 2 days after, each irrigation. By the end of the experiment, about 50% of the applied N had been lost from the top 20 cm of the profile. Ammonium sulfate caused exchangeable cations to move from the 0-5 cm layer, but urea had no effect on cation distribution. The effects of lime application were confined to the upper 10 cm of the soil profile.

A climosequence of soils on late quaternary volcanic ash in highland Papua New Guinea

Some chemical, physical and mineralogical properties of three soils developed in volcanic ash at altitudes of 1040 m, 1720 m, and 2350 m in Papua New Guinea's Enga Province are presented. Silt-fraction mineralogy and total chemical analyses show that fresh ash occurs in the upper approximately 30 cm of profile at each site. This fresh ash is probably only a few thousand years old and overlies an older weathered ash (Tomba Tephra;more than 50000 years old). At the lowest site the majority of the primary minerals (predominantly amphiboles, volcanic glass and felspar, and some pyroxenes) have been decomposed by weathering to produce a high clay content. With increasing altitude, greater proportions of silt-sized, unweathered and partially altered primary minerals are recognised and molar ratios of calcium, magnesium, sodium and potassium to aluminum increase accordingly. In the clay fractions, allophane with Al/Si ratios of approximately 2.0 is dominant at the highest site, whereas with decreasing altitude lower proportions of allophane occur, Al/Si ratios decline and halloysite becomes dominant. Gibbsite is found in all three profiles

THE INFLUENCE OF TILLAGE ON SOIL WATER BEHAVIOR

Three intensities of tillage disturbance were imposed on a deep yellow loamy sand for three successive years. Differences in water release curves of the top 10 centimeters occurred in the first year and persisted through the three years. Air permeability and soil water diffusivity measurements also reflected differences in pore geometry. The distribution of water down the first 70 cm of profile was found to reflect these surface soil differences, with the ploughed treatment having its maximum water content deeper in the profile early in the rainy season. We infer that difference in tillage treatment will continue to affect soil and crop water status in such weakly structured sands.

Factors Determining the Occurrence of Calcifuge Species on Shallow Soils Over Calcareous Substrata

In characterizing ferns and flowering plants as calcicole or calcifuge, ecologists have relied almost entirely upon the correlation of soil analyses with estimates of plant frequency. In many parts of the British Isles, this is a difficult and arbitrary distinction which breaks down completely in certain circumstances, e.g. the case of plants growing in a soil with a vertical or horizontal leaching gradient, such that the root system is in contact with both acid soil and calcareous soil. It is important, moreover, to take account of the possibility of race differentiation within the species or of variation in shallow soils over calcareous substrata with respect to their capacity to support calcifuge vegetation. Tansley & Adamson (1926), Hope Simpson (1938) and De Silva (1934) have obtained consistent results in estimations of the degree of calcicoly shown by grassland species on the Chalk and Greensand of Southern England. When the ecology of species recognized as calcicoles or calcifuges by Tansley & Adamson, is examined in grasslands of northern and western areas of the British Isles, many discrepancies appear. The most striking of these is the association of 'calcifuges' with calcicolous species on shallow limestone soils (Webb 1935; Balme 1953). This paper describes some preliminary studies of associations of this kind observed on soils over the carboniferous limestone in Derbyshire. The following working definitions will be used: 1. A calcareous soil is one in which the pH of a paste prepared from the top 3 cm of the profile exceeds 6-5. 2. A calcifuge is a species which, in the majority of its field situations, grows on soils in which the pH of a paste prepared from the top 3 cm of the profile does not exceed 6 5. These definitions assume that for most British soils the pH will provide an adequate index of the extent to which the cation exchange complex is saturated with calcium, pH estimations being more rapid, convenient and reliable for this purpose than analyses for exchangeable Ca++ or for 'free' calcium carbonate. Fig. 1 shows that shallow highly humified soils over limestone may have detectable free carbonate even in horizons that are extremely acid. The pH determinations were carried out on pastes obtained by adding sufficient water to thoroughly mixed samples of the top 3 cm of the soil profile to bring them to field capacity. The depth of 3 cm was chosen somewhat arbitrarily as the lower limit of a zone in which superficial leaching will be manifest and of which the base status will be likely to have the greatest influence on the successful establishment of species entering either by seed or vegetatively. Recent experimental evidence (Rorison 1960) suggests that certain calcicole seedlings show markedly impaired growth before they penetrate to this depth on acid soils. A pH of 6 5 seems to mark a fairly consistent upper limit