Red soil chemistry and mineralogy reflect uniform weathering environments in fluvial sediments, Taiwan

Purpose

Information on the physicochemical properties, mineral species and micromorphology of lateritic soils and gravel soil layers in paleo-environmental soil profile is severely lacking. Red soil profile of the Taoyuan terrace was employed to demonstrate its different extents of lateritic weathering. The objectives of this study were to compare the physicochemical properties of lateritic soils and gravel soil layers and identify using conventional and synchrotron X-ray diffraction (XRD) analyses mineral species in nanoparticles separated by automated ultrafiltration device (AUD) apparatus.

Materials and methods

Soil samples were collected from paleo-environmental lateritic soils. Soil samples were examined using elemental analysis, conventional and synchrotron XRD analyses, high gradient magnetic separation, separation and collection of nanoparticles by AUD apparatus, and transmission electron microscopy (TEM).

Results and discussion

The soil pH, redness index, quantities of free Al- and Fe-oxides (Al_d and Fe_d), and clay content of lateritic soils are higher than those of gravel soil layers. Illite, kaolinite, gibbsite, quartz, goethite, and hematite were identified in clay fractions and nanoparticles by conventional and synchrotron XRD analyses. TEM images show presence of hematite nanoparticles on the surface coating of kaolinite nanoparticles and aggregated hematite nanoparticles overlapping the edge of a kaolinite flake in a size range of 4?C7?nm. Synchrotron XRD techniques are more straightforward and powerful than conventional XRD with random powder methods for identifying nanoparticles in red soils, particularly for illite, kaolinite, goethite, and hematite nanoparticles. According to chemical compositions of clay fractions and red soil features in the Taoyuan terrace, these red soils can be taken as lateritic red earths or red earths.

Conclusions

This work suggests that physicochemical properties, mineral species, and micromorphology of red soil at all depths can shed light on the extent of paleo-environmental lateritic weathering.     

The impact of iron oxide magnetic nanoparticles on the soil bacterial community

Purpose  

Iron oxide magnetic nanoparticles (IOMNPs) have numerous exciting applications due to their unique chemical and physical properties. With increased applications of engineered nanostructures, releases of such materials to soil are undoubtedly inevitable. Their potential environmental risks have attracted increasing concern. One area of concern is their effect on microorganisms, which are important components of ecosystems.     

Phytoremediation efficiency of a PAH-contaminated industrial soil using ryegrass,white clover,and celery as mono- and mixed cultures

Purpose  

Phytoremediation has been recognized as a promising technology for the remediation of polycyclic aromatic hydrocarbon (PAH)-contaminated soils. However, little is known about how plant species and cropping patterns affect the process of phytoremediation removing PAHs. Therefore, the aim of this study was to investigate further the effects of monocultures or mixed cultures of different plant species on PAH phytoremediation.     

Endocrine disruption in a terrestrial isopod under exposure to bisphenol A and vinclozolin

Background, aim, and scope  

In the past decade there has been an increasing awareness about the possible consequences of human and wildlife exposure to endocrine disrupting compounds (EDCs). Bisphenol A (BPA) and vinclozolin (Vz) are EDCs which impacts on vertebrates have been largely investigated. Nevertheless, research on invertebrate effects, especially on soil organisms, are still largely under-represented. This work aims to extend the limited ecotoxicological datasets available and to provide tools to assess the effects of EDCs on the terrestrial species, using Porcellio scaber (Crustacea: Isopoda) as a model organism.     

Improvement of biochemical and biological properties of eroded red soil by artificial revegetation

Background, aim, and scope  

Large areas of red soil in southern China are degraded due to improper management in land use change from forest to agricultural crops in 1970s, which has resulted in serious soil erosion. Since 1980s, artificial revegetation has been practiced to restore the productivity and maintain ecological functionality of red soils. Whereas numerous studies have been conducted to evaluate the effects of revegetation on soil physical and chemical properties, little information is available on soil microbial responses. The objective of this work was thus to investigate the influence of plant species and growing period on soil biochemical and biological properties.     

Phylogenetic diversity of dissimilatory ferric iron reducers in paddy soil of Hunan, South China

Purpose  

Dissimilatory iron-reducing bacteria have been described by both culture-dependent and -independent methods in various environments, including freshwater, marine sediments, natural wetlands, and contaminated aquifers. However, little is known about iron-reducing microbial communities in paddy soils. The goal of this study was to characterize iron-reducing microbial communities in paddy soil. Moreover, the effect of dissolved and solid-phase iron (III) species on the iron-reducing microbial communities was also investigated by enrichment cultures.     

Effects of single and mixed species forest ecosystems on diversity and function of soil microbial community in subtropical China

Purpose  

The objective of the present study was to evaluate soil microbial community function and diversity among eight single and mixed species forest ecosystems (18-year-old restoration) in subtropical China.     

Phytoremediation for soils contaminated by phenanthrene and pyrene with multiple plant species

Purpose  

The remediation of soil polluted by polycyclic aromatic hydrocarbons (PAHs) is of great importance due to the persistence and carcinogenic properties of PAHs. Phytoremediation has been regarded as a promising alternative among suggested approaches. For the establishment of highly effective remediation method and better understanding of the remediation mechanisms by plants, the potentials of three plant species and their planting patterns on the remediation efficacy were studied by pot experiments.     

In situ phytoremediation of PAH-contaminated soil by intercropping alfalfa (<Emphasis Type="Italic">Medicago sativa</Emphasis> L.) with tall fescue (<Emphasis Type="Italic">Festuca arundinacea</Emphasis> Schreb.) and associated soil microbial activity

Purpose  

A 7-month field experiment was conducted to investigate the polycyclic aromatic hydrocarbon (PAH) remediation potential of two plant species and changes in counts of soil PAH-degrading bacteria and microbial activity.     

Soil soluble organic carbon and nitrogen pools under mono- and mixed species forest ecosystems in subtropical China

Purpose  

The objective of the present study was to assess the differences in soil total C and N, microbial biomass C and N, soil soluble organic C and N among eight mono- and mixed species forest ecosystems (18-year-old restoration) in subtropical China.     

Stress protein response (Hsp70) and avoidance behaviour in Eisenia fetida, Aporrectodea caliginosa and Lumbricus terrestris when exposed to imidacloprid

Purpose  

The earthworm species Eisenia fetida and Eisenia andrei are commonly used in ecotoxicological standard tests. In the present study, we compared the sensitivity of E. fetida with that of two soil-dwelling earthworm species (Aporrectodea caliginosa and Lumbricus terrestris) in order to evaluate the capacity of E. fetida to predict effects of the insecticide imidacloprid. Responses were compared using two endpoints, a biochemical (changes in heat shock protein level (hsp70)) and a behavioural (avoidance behaviour).     

Influence of iron plaque on accumulation of lead by yellow flag (<Emphasis Type="Italic">Iris pseudacorus</Emphasis> L.) grown in artificial Pb-contaminated soil

Purpose  

The relationship between plant absorption and accumulation of heavy metals and the effect of iron plaque on roots of wetland plants are unknown, especially for plants grown in heavy metal-contaminated soil. This experiment was designed to study the effects of iron addition on the formation of iron plaque in the rhizosphere of the wetland plant species Iris pseudacorus L. in artificial Pb-contaminated soil and the effects of iron plaque on Pb accumulation by plants.     

Plant-induced changes in the bioavailability of heavy metals in soil and biosolids assessed by DGT measurements

Purpose  

This study investigated the effects of plants on the available pools of heavy metals and their re-supply potential in contaminated substrates in a short-term experiment using five metal-accumulating willow and poplar species/cultivars and in a longer-term experiment for Salix x reichardtii.     

Sensitivity of <Emphasis Type="Italic">Eisenia fetida</Emphasis> in comparison to <Emphasis Type="Italic">Aporrectodea caliginosa</Emphasis> and <Emphasis Type="Italic">Lumbricus terrestris</Emphasis> after imidacloprid exposure. Body mass change and histopathology

Purpose  

The use of only one or a few species—representing an entire taxon—in ecotoxicological standard tests poses risk of underestimating the impact of toxicants on the environment. In earthworm ecotoxicity tests, the species Eisenia fetida or Eisenia andrei are commonly used, and there is evidence that these species respond relatively insensitive towards environmental pollution. With the present study, we wanted to evaluate the risk of underestimating effects of the insecticide imidacloprid in soil organisms by comparing E. fetida with two other earthworm species (Aporrectodea caliginosa and Lumbricus terrestris) regarding their sensitivities towards soil contaminated with this widely used insecticide.     

Aluminium geochemistry in the bulk and rhizospheric soil of the species colonising an abandoned copper mine in Galicia (NW Spain)

Purpose  

Aluminium partitioning in the solid fraction and aluminium in solution in the bulk and rhizospheric soil of different plant species colonising an abandoned Cu mine slope (Calluna vulgaris, Erica cinerea and Salix atrocinerea) and mine dump (C. vulgaris and E. cinerea) were investigated. The aim of the study was to determine the changes that the species induce in the Al forms in the rhizosphere in order to adapt to heterogeneous substrates.     

Soil fungal communities differ in native mixed forest and adjacent <Emphasis Type="Italic">Araucaria cunninghamii</Emphasis> plantations in subtropical Australia

Purpose  

Commercial monoculture plantations of the native Australian Araucaria cunninghamii are common in subtropical and tropical Queensland and are generally established following clearing of native mixed forest. The consequences of such forest conversion for soil fungal communities, however, have not been assessed in detail.     

Evaluation of the mayfly <Emphasis Type="Italic">Ephoron virgo</Emphasis> for European sediment toxicity assessment

Purpose  

The mayfly Ephoron virgo plays a key role in the ecological recovery in large European rivers. The larvae spend their life in the sediment and are therefore exposed to contaminants in various ways. In this study, the use of E. virgo as a test species for whole sediment bioassays was evaluated. The sensitivity was compared with Hexagenia limbata (a North American mayfly recommended for standard sediment testing). Lead (Pb) was used as a model contaminant.     

Chronic toxicity of ivermectin to the benthic invertebrates <Emphasis Type="Italic">Chironomus riparius</Emphasis> and <Emphasis Type="Italic">Lumbriculus variegatus</Emphasis>

Purpose  

Previous studies have shown that ivermectin, a widely used parasiticide, is very toxic to many non-target invertebrate species. In view of the strong binding of ivermectin to sediments and the scarcity of data on chronic toxicity to freshwater sediment invertebrates, chronic effects of the parasiticide on the midge Chironomus riparius and the oligochaete Lumbriculus variegatus were investigated.     

Revisiting the fundamentals of phosphorus fractionation of sediments and soils

Introduction  

Sequential fractionation procedures have been an important tool in the study of phosphorus (P) dynamics in soils and sediments for over 50 years. Throughout this period, the various methodologies have been thoroughly reviewed, and several limitations are widely acknowledged, but there are also aspects of P fractionation that have received little or no discussion. As there are few alternatives to fractionation procedures, in order to advance the usefulness of these techniques, we need to explore the undisclosed variables that may falsely bias our interpretation.     

Effects of plant rhizosphere on mercury methylation in sediments

Purpose  

This research investigates the effects of different plant species on Hg methylation rates, examines the difference in mercury (Hg) methylation rates in the plant rhizospheres, and shows the trend in methylmercury (MeHg) content of sediment in the Second Songhua River (SSR) of China, thereby providing the basis for estimating the ecological risk of this area.