Soil Exposure Research Articles

The effects of heavy metal exposure in agriculture soil on chlorophyll content of agriculture crops: A meta-analysis approach

Soil can be contaminated by the accumulation of heavy metals and metalloids through emissions from rapidly developing industrial areas. Due to the possibility of chemical change (speciation) and their bioavailability, the presence of toxic metals in the soil can greatly inhibit the biodegradation of organic contaminants. The researchers aimed to analyse the effect of heavy metal levels in agricultural soil on chlorophyll levels in agricultural crops through a meta-analysis method which is expected to provide results in the form of a summary of data that already exists in journals that have been published so far. Here we present a meta-analysis of 6 studies (56 data collected) published between 1997 and 2020 that reported the effects of heavy metal content on plant chlorophyll content. Based on the meta-analysis of the effect of heavy metal exposure in agricultural soil on the chlorophyll content of agricultural crops, the value “effect size overall” was -0.285 in the range of -0.380 to -0.190, where most of the values “effect size” were on the left. Plants growing on soil contaminated with heavy metals result in decreased growth due to changes in physiological and biochemical activities, especially when heavy metals inhibit plant growth and development. Furthermore, environmental risk assessment due to mercury exposure is very important to control the transport and accumulation of mercury in the biosphere to reduce the impact of mercury on the environment.

Responses of Ammonia Oxidizing Microorganisms to Single and Combined Sulfamethazine and Cadmium Exposure in Soil

Responses of Ammonia Oxidizing Microorganisms to Single and Combined Sulfamethazine and Cadmium Exposure in Soil

Bioaccumulation and Toxicity of Titanium Dioxide Nanoparticles in Epigeic Earthworm Species Eudrilus eugeniae

The production of titanium dioxide nanoparticles (TiO2) for commercial applications has greatly increased over the last years and consequently the potential risk for living organisms. There is a growing awareness of the need to understand the behavior and influence these nanoparticles exert on the environment. Bioaccumulation serves as a good integrator to assess chemical exposure in soil. This research focused on the experimental bioaccumulation capability of titanium dioxide nanoparticles (TiO2 ) by Earthworms Eudrilus eugeniae. It is found that TiO2 exerted minimal toxicity within the traditional 48 h exposure time, but caused high toxicity when the exposure time was extended to 72 h. This demonstrated that exposure duration may be a contributing factor in NP-mediated toxicity. Moreover, upon chronic exposure to TiO2 for 21 days, earthworm displayed severe growth retardation and mortality, as well as reproductive defects. A significant amount of TiO2 was found accumulated in Eudrilus eugeniae. However, Eudrilus eugeniae displayed difficulty in eliminating TiO2 from their body, presenting increased bioconcentration factor (BCF) values. This high level of bioaccumulation may interfere with food intake and ultimately affect growth and reproduction. In a nutshell, longterm exposure of soil organisms to TiO2 may alter the growing status of these organisms at both individual and population levels, posing risks to ecosystems. The results of this study contribute to the current understanding of the potential ecotoxicological effects of nanoparticles and highlight the importance of characterization of NPs in understanding their behavior, uptake, and effects on organisms in soil

Enterobacteriaceae in soils and atmospheric dust aerosol accumulations of Moscow city.

The topsoils and atmospheric dust aerosols of the various areas of the city of Moscow were studied. Most of the dust samples contained a considerable number of particles enriched in phosphorus - a sign of contamination by feces. A variety of Enterobacteriaceae species, including opportunistic and pathogenic species, were isolated from the topsoil and dust samples and identified using 16S rDNA nucleotide sequences: Enterobacter aerogenes, E. agglomerans, E. cloacae, E. kobei, E. nimipressuralis, Escherichia coli, Citrobacter europaeus, Klebsiella granulomatis, K. grimontii, K. oxytoca, K. quasipneumoniae, K. variicola, Kluyvera ascorbate, Kluyvera intermedia, Leclercia adecarboxylata, Salmonella enterica and Trabulsiella guamensis. The greatest diversity of pathogens was isolated from spring soil and dust samples immediately after spring snowmelt. Antibiotic resistance of the isolated E. coli strains was tested using disks with a wide range of antimicrobial drugs: Amoxicillin, Ampicillin, Meropenem, Pefloxacin, Streptomycin, Ticarcillin+clavulanic acid, Fosfomycin, Ceftibuten, Ciprofloxacin. Resistance was observed in more than 22% of E. coli strains. The traffic area had a significant number of antibiotic-resistant E. coli strains, clearly indicating a high health risk from soil and dust exposure.

Effects of Short-Term Exposure of Soil to Different Doses of Nano-Zinc Oxide on the Soil Environment and the Growth and Nitrogen Fixation of Alfalfa

Effects of Short-Term Exposure of Soil to Different Doses of Nano-Zinc Oxide on the Soil Environment and the Growth and Nitrogen Fixation of Alfalfa

Coletor solar para desinfestação de solo para a produção de mudas de tomateiro livres de Meloidogyne enterolobii em condições semiáridas

ABSTRACT: In this study, we validated a solar collector for disinfest soil infested by Meloidogyne enterolobii for tomato seedlings production in semiarid conditions. An experiment using a randomized block design was conducted with six exposure times of the sieved substrate in the solar collector of zinc tubes. The treatments consisted of 0 (control), 6, 12, 24, 30 and 36 hours of exposure, with five replicates. After 12 hours of soil exposure in the solar collector, no galls were observed in the tomato roots, neither were eggs and second stage juveniles of M. enterolobii were observed in the soil. Based in the results obtained in this study, the solar collector was efficient in the disinfest of soil infested by M. enterolobii aiming production of tomato seedlings in semiarid conditions.

Assessment of self-adjustment of tillage working bodies to soil conditions

Assessment of self-adjustment, that is, automatically adjusting parameters of tillage working bodies as a result of soil exposure, is an urgent task, since it is associated with the problem of developing energy-efficient tillage units. The purpose of the research is to assess the self-adjustment of typical and dynamic tillage working bodies to specific soil conditions during their functioning. The objects of research are a dynamic tillage working body with an energy-storage transmitting device and a typical tillage working body for continuous surface treatment of various soil types. The subject of research was the indicators of self-adjustment of tillage working bodies to soil conditions. During the research, methods of mathematical modeling, strain measurement of tillage working bodies, analysis and generalization of experimental data were used. The scientific novelty of the work is represented by the selected criteria for assessing the self-adjustment of working bodies and the patterns of their change from the movement speed. As criteria for assessing the self-adjustment of tillage working bodies, the following were selected: the coefficient of terradynamic resistance, the specific traction resistance per unit of its active frontal area, the number of degrees of freedom of the tillage working body and indicators for assessing the tillage quality. Based on the proposed evaluation criteria, it was experimentally established that the dynamic tillage working body developed by the authors with an energy-storage transmitting device is more efficient and adapted to changing soil conditions in comparison with a typical working body, which provides a reduction in traction resistance by an average of 20% and an increase in the degree of soil loosening by an average of 8.4-8.8% compared with typical working bodies.

An integrated approach to quantify ecological and human health risks of soil heavy metal contamination around coal mining area

Soil heavy metals harm ecological biodiversity and human health, and quantifying the risks more accurately is still obscure. In this study, a network environ analysis was applied to quantify risks between ecological communities based on control allocation and human health risk models to calculate human health exposure risks from soil heavy metals around Greenside coal mining in South Africa. Ecological and human health risks were apportioned using PMF model. Results showed assessed heavy metals (mean) exceeded local background content with a cumulative of moderately polluted using pollution load index (PLI). Total initial risk (Ri), the risk to biological organisms from direct soil exposure, was 0.656 to vegetation and 1.093 to soil microorganisms. Risk enters the food web via vegetation and harms the whole system. Integrated risks (initial, direct, and indirect) to vegetation, herbivores, soil microorganisms, and carnivores were 0.656, 0.125, 1.750, and 0.081, respectively, revealing that soil microorganisms are the most risk receptors. Total Hazard Index (HIT) was <1 for adults (0.574) whereas >1 for children (4.690), signifying severe non-cancer effects to children. Total cancer risk (TCR) to children and adults surpassed the unacceptable limit (1.00E-04). Comparatively, Cr is a high-risk metal accounted for 63.24% (adults) and 65.88% (children) of the HIT and 92.98% (adults) and 91.31% (children) of the TCR. Four sources were apportioned. Contributions to Ri (soil microorganisms and vegetation) from F3 (industrial), F4 (atmospheric), F2 (coal mining), and F1 (natural) were 42.20%, 24.56%, 23.55%, and 9.68%, respectively. The non-cancer risk from F3 (37.67% to adults and 38.40% to children) was dominant, and TCR to children from the sources except F1 surpassed the unacceptable limit. An integrated approach of risk quantification is helpful in managing risks and reducing high-risk pollution sources to better protect the environment and human health.

Modeling the short-term fire effects on vegetation dynamics and surface energy in southern Africa using the improved SSiB4/TRIFFID-Fire model

Abstract. Fire causes abrupt changes in vegetation properties and modifies flux exchanges between land and atmosphere at subseasonal to seasonal scales. Yet these short-term fire effects on vegetation dynamics and surface energy balance have not been comprehensively investigated in the fire-coupled vegetation model. This study applies the SSiB4/TRIFFID-Fire (the Simplified Simple Biosphere Model coupled with the Top-down Representation of Interactive Foliage and Flora Including Dynamics with fire) model to study the short-term fire impact in southern Africa. Specifically, we aim to quantify how large impacts fire exerts on surface energy through disturbances on vegetation dynamics, how fire effects evolve during the fire season and the subsequent rainy season, and how surface-darkening effects play a role besides the vegetation change effects. We find fire causes an annual average reduction in grass cover by 4 %–8 % for widespread areas between 5–20∘ S and a tree cover reduction by 1 % at the southern periphery of tropical rainforests. The regional fire effects accumulate during June–October and peak in November, the beginning of the rainy season. After the fire season ends, the grass cover quickly returns to unburned conditions, while the tree fraction hardly recovers in one rainy season. The vegetation removal by fire has reduced the leaf area index (LAI) and gross primary productivity (GPP) by 3 %–5 % and 5 %–7 % annually. The exposure of bare soil enhances surface albedo and therefore decreases the absorption of shortwave radiation. Annual mean sensible heat has dropped by 1.4 W m−2, while the latent heat reduction is small (0.1 W m−2) due to the compensating effects between canopy transpiration and soil evaporation. Surface temperature is increased by as much as 0.33 K due to the decrease of sensible heat fluxes, and the warming would be enhanced when the surface-darkening effect is incorporated. Our results suggest that fire effects in grass-dominant areas diminish within 1 year due to the high resilience of grasses after fire. Yet fire effects in the periphery of tropical forests are irreversible within one growing season and can cause large-scale deforestation if accumulated for hundreds of years.

Nanoplastic Transport in Soil via Bioturbation by Lumbricus terrestris.

Plastic pollution is increasingly perceived as an emerging threat to terrestrial environments, but the spatial and temporal dimension of plastic exposure in soils is poorly understood. Bioturbation displaces microplastics (>1 μm) in soils and likely also nanoplastics (<1 μm), but empirical evidence is lacking. We used a combination of methods that allowed us to not only quantify but to also understand the mechanisms of biologically driven transport of nanoplastics in microcosms with the deep-burrowing earthworm Lumbricus terrestris. We hypothesized that ingestion and subsurface excretion drives deep vertical transport of nanoplastics that subsequently accumulate in the drilosphere, i.e., burrow walls. Significant vertical transport of palladium-doped polystyrene nanoplastics (diameter 256 nm), traceable using elemental analysis, was observed and increased over 4 weeks. Nanoplastics were detected in depurated earthworms confirming their uptake without any detectable negative impact. Nanoplastics were indeed enriched in the drilosphere where cast material was visibly incorporated, and the reuse of initial burrows could be monitored via X-ray computed tomography. Moreover, the speed of nanoplastics transport to the deeper soil profile could not be explained with a local mixing model. Earthworms thus repeatedly ingested and excreted nanoplastics in the drilosphere calling for a more explicit inclusion of bioturbation in nanoplastic fate modeling under consideration of the dominant mechanism. Further investigation is required to quantify nanoplastic re-entrainment, such as during events of preferential flow in burrows.

On a Data-Driven Approach for Detecting Disturbance in the Brazilian Savannas Using Time Series of Vegetation Indices

Remote sensing of disturbance in the savannas from Brazil is challenging, especially due to confounding effects of the vegetation phenology and natural soil exposure on the detection of clearing and fire events. In this study, we investigated the detection of disturbance over this global hotspot of biodiversity using seven vegetation indices (VIs) calculated from the Landsat time series (2017–2019) and the Continuous Change Detection and Classification (CCDC) algorithm. The selected VIs represented distinct biophysical characteristics of the savannas. We evaluated the effects of disturbance on these VIs and assessed the accuracy of CCDC-detection in 2019, considering individual VIs, ensemble VIs, and the type of disturbance (savanna clearing and fire). Finally, we analyzed the possible existence of seasonal patterns of disturbance in a study area located at the new agricultural frontier of the Cerrado biome. The results showed that the overall accuracy of CCDC detection of total disturbance ranged from 51.2% for the Green-Red Normalized Difference (GRND) to 65.9% for the Normalized Burn Ratio (NBR2). It increased to 71.2% for ensemble VIs, whose multivariate approach reduced the omission errors in the analysis when compared to the use of single VIs. For detecting events of savanna clearing and fire, the most important VIs used near-infrared and shortwave infrared reflectance bands on their formulations (NBR2, NBR, and Moisture Stress Index—MSI). The CCDC accuracy was generally higher for detecting clearing than for mapping burned areas. In contrast, the recorded date of disturbance occurrence was less precise for detecting clearing than for recording events caused by fire, especially due to the existence of some gradual processes of vegetation degradation until complete clearing. Our findings showed also the existence of a seasonal pattern of disturbance occurrence. Savanna clearing predominated in the transition from the rainy to the dry season (April to July) to open new areas for agriculture. It preceded most events of fire disturbance between August and October that occurred near the consolidated areas of agriculture and extended into the native vegetation areas. Results reinforce the importance of data-driven approaches for generating early warning alerts of disturbance in the Cerrado to be further checked in the field.

Effects of adding different proportions of soft rock on the dynamic change of the quality of aeolian sandy soil

Evolution process of quality of soft rock and sand compound soil and exploration of its stability were studied. In the present study different proportions (1 : 1, 1 : 2, 1 : 5, 0 : 1) of soft rock and sand compound soil as the research object were selected. Tthe particulate organic carbon, microbial organic carbon, effective phosphorus, quick-acting potassium, nitro nitrogen and ammonium nitrogen in the compound soil were analyzed. Results showed that after 9 years of planting, the organic carbon content of particles with 0 : 1 treatment was the lowest, at 1.73 g/kg, and the treatment of 1 : 5 and 1 : 1 increased significantly by 74.74 and 94.90%, respectively. In the 20 - 30 cm soil layer, the lowest organic carbon content of particles with 1 : 2 treatment was 1.92 g/kg, and there was no significant difference between the other three treatments, with 0 : 1, 1 : 5 and 1 : 1 treatment increased by 46.20, 29.27 and 34.07%, respectively compared to 1 : 2 treatment. With developed root system, the biomass of the root system was greater than the biomass left on the ground after harvest, and the average content of organic carbon of the particles increased first and then decreased later. The microbial community in the compound soil was significantly improved, and the carbon content of microorganisms in the treatment of 1 : 1, 1 : 2 and 1 : 5 was significantly higher than that of whole sand by 85, 165 and 143%, respectively, after multi-year of cultivation. The soil root microbial community showed a benign development. With the increase of planting years, the incorporation of soft rock accelerates the process of natural succession of soil quality. Compared with sandy land, compound soil has significantly improved storage of available phosphorus and available potassium nutrients. Compound soil has been cultivated for 9 years compared with 6 years, with the ratio of 1 : 1, 1 : 2, 1 : 5 and 0 : 1, the effective phosphorus content increased significantly by 141, 181, 169 and 63% respectively, the available potassium content increased significantly by 141, 181, 169 and 63% respectively. Compound soil has been cultivated for 9 years compared with 6 years, with the ratio of 1 : 1, 1 : 2, 1 : 5, and 0 : 1, the nitrate nitrogen content increased significantly by 40, 130, 135 and 120%, respectively. Nitro nitrogen is easily soluble in water, and the higher the proportion of sand in the compound soil, the easier the loss of nitrous nitrogen content in the soil. After multiple years of cultivation, the ammonium nitrogen content in the compound soil decreased, with a significant decrease of 35 (p &lt; 0.05), 34 (p &lt; 0.05), 45 (p &lt; 0.05) and 37% (p &lt; 0.05), respectively. Due to the disruption of harvest, the exposure of the surface soil is high, which causes ammonium nitrogen to evaporate. Bangladesh J. Bot. 50(3): 837-845, 2021 (September) Special

Polybrominated diphenyl ethers concentrations in metals and plastics scrap impacted soils: Pollution load, sources, ecological, and onsite human health implications

The usage of polybrominated diphenyl ethers (PBDEs) as fire-resistant additives was banned several years ago; however, they persist in several environmental compartments. This study determined the concentrations and associated exposure risks of Ʃ39PBDEs in soil depth samples from selected metals and plastics scrap catchments in the Niger Delta region, Nigeria. Samples extraction was performed by the Soxhlet extraction method followed by GC-MS analysis. The mean concentrations of ∑39PBDEs-congeners ranged from 0.01 ± 001 to 25 ± 11.0 ng g−1 in the topsoil and 0.01 ± 0.01 to 6.50 ± 4.7 ng g−1 in the subsoil. The PBDE homologue profiles were dominated by di, penta, hexa, and tri-BDEs. The PBDEs cancer and non-cancer risk for infants were higher than those in adults, expressed in the following order: ingestion > dermal contact > inhalation. In general, the sum for the three exposure pathways was within the allowable threshold limit, suggesting a low lifetime cancer risk from soil exposures. The technical mixture used for paints, plastics, hydraulic, and dielectric insulating fluids for transformers, capacitors, cable wires, and power capacitors is a potential source of Ʃ39PBDEs in the study area. With the increase in metals scrap enterprise in Nigeria, this study provides empirical data useful for the development of efficient strategies to strengthen and enforce existing regulations for metals and plastics scrap land use in Nigeria and other similar catchments around the world.

Mechanisms of Anaerobic Soil Disinfestation: Volatile Fatty Acids Reduce Viability of Athelia (Sclerotium) rolfsii Sclerotia in Acidic Soil Conditions and Have Limited Effects on Endemic Trichoderma spp.

Volatile fatty acids (VFAs), such as acetic and n-butyric acid, released during anaerobic decomposition of organic soil amendments during anaerobic soil disinfestation (ASD) likely play a role in soilborne plant pathogen inoculum suppression. However, research is limited on the direct effects of soil VFA exposure on fungal plant pathogen inoculum, effects on pathogen antagonists such as Trichoderma spp., and the role of soil microbial VFA metabolism on reducing exposure effects. The present study addresses these limitations through a series of studies evaluating the effects of VFA (acetic or n-butyric acid), VFA concentration (4, 8, or 16 mmol/kg soil), soil sterilization by autoclaving, and soil amendment on the viability of Athelia rolfsii (Sclerotium rolfsii) sclerotia post VFA exposure, and soil populations of Trichoderma spp. HCl and water-only controls were included. After 4-days exposure in an acidic, anaerobic environment, sclerotial viability, and colonization by culturable fungi or bacteria were assessed with standard procedures. Greenhouse experiments were similarly conducted to evaluate endemic soil populations of Trichoderma spp. following soil exposure to VFAs and Trichoderma spp. populations assessed with standard soil dilution plating onto semi-selective medium. Sclerotial germination was generally reduced by soil exposure to acetic (35.1% germination) or n-butyric (21.9% germination) acids compared to water (74.3% germination) and HCl (62.7% germination). Germination was reduced as VFA concentration increased from 4 to 8 and 16 mmol/kg (39.5, 29.1, and 16.9%, respectively). In amended soils, there was no difference in sclerotial germination compared to non-amended soils, but in the greenhouse experiment there was a Trichoderma spp. population increase of over 300% in amended soil [3.4 × 106 colony forming units (CFU)/g soil] compared to the non-amended soil (9.6 × 105 CFU/g soil). Soil autoclaving had no effect on sclerotial germination at low VFA concentrations, but sclerotial germination was reduced at higher VFA concentrations compared to non-autoclaved soil. Our results suggest that VFAs contribute to sclerotial mortality in strongly acidic soil environments, and mortality is influenced by VFA components and environment. Antifungal activity is less for acetic acid than for n-butyric, and less in non-sterile soil environments more typical of field conditions than in sterile laboratory conditions.

Effects of Co-Exposure of Nanoparticles and Metals on Different Organisms: A Review.

Wide nanotechnology applications and the commercialization of consumer products containing engineered nanomaterials (ENMs) have increased the release of nanoparticles (NPs) to the environment. Titanium dioxide, aluminum oxide, zinc oxide, and silica NPs are widely implicated NPs in industrial, medicinal, and food products. Different types of pollutants usually co-exist in the environment. Heavy metals (HMs) are widely distributed pollutants that could potentially co-occur with NPs in the environment. Similar to what occurs with NPs, HMs accumulation in the environment results from anthropogenic activities, in addition to some natural sources. These pollutants remain in the environment for long periods and have an impact on several organisms through different routes of exposure in soil, water, and air. The impact on complex systems results from the interactions between NPs and HMs and the organisms. This review describes the outcomes of simultaneous exposure to the most commonly found ENMs and HMs, particularly on soil and aquatic organisms.

Manage the environmental risks of perovskites

Manage the environmental risks of perovskites

Sustainable health-based soil standards for arsenic using epidemiological data and toxicokinetic/probabilistic modelling.

This study presents an alternative method to the traditional reference dose approach for the determination of health risk-based soil standards for arsenic. The model combines multimedia equations for air, soil and dietary exposure, a toxicokinetic component, a probabilistic output, a reference distribution for urine arsenic in the general population and exposure parameters values traceable in US-EPA or EFSA reference studies. The model calculates a mean inorganic As urine concentration AsU (sum of inorganic arsenic Asi and its metabolites) from environmental data and exposure parameters, which is attributed to the central value of a lognormal distribution. Risk is assessed by comparing a high percentile of the modelled distribution to the target AsU attributed to the reference value of 10µg/gCREA (microgram As per gram of creatinine), the upper confidence interval of the 95th percentile from the AsU distribution in the French population. A soil standard value of 40mg/kg is determined as being the arsenic concentration in soil not giving rise to more than 5% probability of having a AsU concentration above the target value of 10µg/gCREA. Once soil As concentrations above 40mg/kg are measured, further environmental investigations should be carried, involving an assessment of As bioaccessibility to address health risks and decide of regulatory measures in residential setting.

Distinct response patterns of bacterial communities in Ag- and ZnO-rGO nanocomposite-amended silt loam soils

The widespread application of metal-based nanoparticle (MNPs)/reduced graphene oxide (rGO) composites inevitably leads to their release into soils. However, we lack a detailed understanding of the bacterial community response to MNPs-rGO exposure in farmland soils. Here, we conducted a soil microcosm experiment to analyze the potential impact of MNPs-rGO on bacterial communities in two field soils via high-throughput sequencing. The change in alpha diversity of bacterial communities was more susceptible to Ag-rGO and ZnO-rGO treatments than CuO-rGO. In both soils, MNPs-rGO significantly changed the bacterial community structure even at a low dose (1 mg kg−1). The bacterial community structure was most strongly affected by Ag-rGO at 30 days, but the greatest changes occurred in ZnO-rGO at 60 days. The differences in soil properties could shape bacterial communities to MNPs-rGO exposure. Distance-based redundancy analysis and functional annotation of prokaryotic taxa showed that some bacterial species associated with nitrogen cycling were greatly influenced by Ag-rGO and ZnO-rGO exposure. In sum, Ag-rGO and ZnO-rGO may potentially affect bacterial communities and nitrogen turnover under long-term realistic field exposure. These findings present a perspective on the response of bacterial communities to MNPs-rGO and provide a fundamental basis for estimating the ecological behavior of MNPs-rGO.

Response of Antarctic soil fauna to climate-driven changes since the Last Glacial Maximum.

Understanding how terrestrial biotic communities have responded to glacial recession since the Last Glacial Maximum (LGM) can inform present and future responses of biota to climate change. In Antarctica, the Transantarctic Mountains (TAM) have experienced massive environmental changes associated with glacial retreat since the LGM, yet we have few clues as to how its soil invertebrate-dominated animal communities have responded. Here, we surveyed soil invertebrate fauna from above and below proposed LGM elevations along transects located at 12 features across the Shackleton Glacier region. Our transects captured gradients of surface ages possibly up to 4.5million years and the soils have been free from human disturbance for their entire history. Our data support the hypothesis that soils exposed during the LGM are now less suitable habitats for invertebrates than those that have been exposed by deglaciation following the LGM. Our results show that faunal abundance, community composition, and diversity were all strongly affected by climate-driven changes since the LGM. Soils more recently exposed by the glacial recession (as indicated by distances from present ice surfaces) had higher faunal abundances and species richness than older exposed soils. Higher abundances of the dominant nematode Scottnema were found in older exposed soils, while Eudorylaimus, Plectus, tardigrades, and rotifers preferentially occurred in more recently exposed soils. Approximately 30% of the soils from which invertebrates could be extracted had only Scottnema, and these single-taxon communities occurred more frequently in soils exposed for longer periods of time. Our structural equation modeling of abiotic drivers highlighted soil salinity as a key mediator of Scottnema responses to soil exposure age. These changes in soil habitat suitability and biotic communities since the LGM indicate that Antarctic terrestrial biodiversity throughout the TAM will be highly altered by climate warming.

Characterization of soil magnetic susceptibility: a review of fundamental concepts, instrumentation, and applications

The characterization of magnetic susceptibility (MS) has become an accepted technique in soil science. This review examines the concept of volume and mass-specific MS, magnetism, frequency dependence, and thermal behavior of MS, as they pertain to soil material. A comparison is presented of the two types of instrumentation for measuring soil MS, based on magnetic field and electromagnetic induction (EMI). These are discussed with respect to applications including magnetic granulometry, detection of pollutants, identification of organic matter, the delineation of drainage class, paleo-environmental studies, archaeology, as well as soil erosion and degradation. Instruments that use magnetic fields can precisely measure the MS of small amounts of soil, thinly deposited layers or soil exposures, but cannot effectively measure materials at distances ≥10 cm from the sensor. EMI instruments, instead, are capable of quickly measuring apparent MS of a finite volume of the soil, and are utilized in mapping of soil MS in agricultural and archaeological investigations; however, the measured apparent MS values need to be further processed to give the real volume MS values of soil layers/segments. Although both kinds of instruments are widely used in soil science, their measured data are not interchangeable. Future work should be conducted to increase the understanding of the comparability of these instruments to find better utility among soil scientists.