Effect Of Soil Aging Research Articles

Effect of Soil Aging on Cadmium Bioavailability and Bioaccessibility at a Contaminated Site

The effect of aging on cadmium (Cd) bioavailability and bioaccessibility was investigated in naturally aged field soil within a contaminated site. The results, which are based on a comparison of investigations carried out in 2018 and 2022 on the same soil samples, provide a realistic evaluation of the variation in Cd chemical forms due to long-term aging. The data obtained show a significant reduction (from approximately 30% to 60%) in the mobile and bioavailable forms of cadmium, while the total quantity in soil did not change significantly. The effect of aging on the bioavailable fractions is also reflected in the reduction in the amount of the metal absorbed by plants. On the one hand, this indicates a reduction in the potential contamination of the food chain, while on the other, it highlights the limitations of the use of phytoextraction as a clean-up technology in this specific site. In the case under study, it should also be noted that there was no decrease in cadmium bioaccessibility over time, which remained very high even after four years of cadmium aging in the soil, which was about 60% of the total content in the most contaminated soil samples. This highlights the potential health risks related to the incidental ingestion of Cd-contaminated soil, which could become the main exposure route in the case of the final use of the site as a park or public green area.

Influence of soil aging on SPT-Vs correlation and seismic site classification

This study examines the influence of soil aging on Standard Penetration Test (SPT) N-Vs correlations, and seismic site classification. Energy-corrected SPT-Vs correlations are developed for two regions where subsurface layering consists of soil deposits with very young geotechnical ages according to the last critical soil disturbance that occurred in the study areas. It is observed that the uncorrected correlations of the current study fall into the lower bound of the uncorrected SPT-Vs correlations existing in the literature due to soil aging effects. To better illustrate the effects of soil aging on SPT-Vs correlations, the uncorrected correlations from the literature and this study are divided into two age categories of Holocene and Pleistocene according to their geological age. Using the two age categories, the boundaries proposed in the NEHRP for different seismic site classes are divided into three zones according to their uncertainty level regarding seismic site classification. The results clearly indicate the need to consider the age of soil deposits for seismic site classification when using the SPT method to avoid incorrect seismic site classification. Additionally, it is found that the use of raw (uncorrected) SPT N values can lead to incorrect seismic site classification, with either conservative or unconservative results depending on the Energy Transfer Ratio (ETR) of the SPT hammer used for the seismic site class determination.

Settlement of jacked piles in clay: Theoretical analysis considering soil aging

This paper develops an analytical approach to estimate the long-term load-displacement behaviors of jacked piles in clayey soils. Apart from considering the effects of pile installation, subsequent re-consolidation and loading, the proposed approach properly considers the effects of soil aging on the long-term behavior of the surrounding soil so as to determine the load-displacement response of the jacked pile in the long run. An elastic-viscoplastic soil model is incorporated into the load transfer method to predict long-term soil properties. The comparison between the predictions from the presented approach and the data measured from the field pile loading test shows the validity of the proposed method. Parametric studies are conducted to illustrate the effects of the in-situ overconsolidation ratio, internal friction angle and the secondary consolidation coefficient on the long-term load-displacement behaviors of old piles. Results show that the proposed approach not only is capable of predicting the short-term set-up of jacked piles, but also could yield reasonable long-term load carrying behavior. The three parameters pertaining to the strength and stiffness of soil have significant impacts on the long-term load-displacement curve of the pile.

Field-aged biochar stimulated N2O production from greenhouse vegetable production soils by nitrification and denitrification

Evidence suggests that biochar is among ideal strategies for climate change mitigation and sustainable agriculture. However, the effects of soil aging on the physicochemical characteristics of biochar and nitrous oxide (N2O) production remain elusive. We set up a microcosm experiment with two greenhouse vegetable production (GVP) (alkaline and acid) soils by using the 15N tracing technique and quantitative polymerase chain reaction (qPCR) to investigate the mechanisms of N2O production as affected by fresh (FB) and aged biochar (AB) amendment. The results showed that AB increased the specific surface area, organic C, ammonium sorption capacity and cation exchange capacity, whereas decreased the pore size and pH relative to the FB. Results also demonstrated that FB effectively decreased N2O emissions from both soils while it enhanced the abundance of nirK and nosZI genes in alkaline soil and reduced the abundance of ammonia-oxidizing bacteria (AOB) amoA and increased nirK and nosZII genes in acid soil. In contrast, AB significantly stimulated nitrification and denitrification in both soils and thus significantly increased the N2O emissions by 43–78%. Furthermore, AB induced increases in ammonia-oxidizing archaeal (AOA) amoA and nirK gene abundances in alkaline soil and fungal nirK gene abundances in acid soil. These results suggest that AB may not be suitable for the mitigation of soil N2O emissions in GVP soils thus improving our understanding of the potential mechanism of biochar in N2O emissions.

Influence of Soil Aging and Stabilization with Compost on Zn and Cu Fractionation, Stability, and Mobility

To determine the effect of soil aging (1, 12, or 24 months) and compost maturation time on metal redistribution and mobility, soil artificially contaminated with Zn and Cu was stabilized with compost for 35, 24, or 12 months. The compost was produced from municipal sewage sludge, wood chips, rape straw, and grass, matured for 3 or 12 months, then used as a soil amendment at a dosage of 20% (w/w). The total time in each series, including aging of spiked soil and its stabilization with compost, was 36 months. The results showed that soil aging reduced CaCl2 extractable Zn fraction and increased Zn stability (as reduced partition index, IR) more than compost addition, which only reduced Zn mobility in soils that had been aged for 1 and 12 months. However, after soil that had been previously aged 1 month was incubated with compost for one year, Zn mobility started to increase. Composts did not influence the changes in the IR of Zn over time. In contrast, compost addition increased Cu stability more than soil aging did, whereas soil aging and compost addition had a negligible effect on Cu mobility. The IR of Cu in all amended soils averaged 0.51, and reached a maximum of 0.57 12 months after addition of compost to soil previously aged for 12 months. Importantly, the maturation time of compost did not affect the mobility or stability of either metal.

Effect of Soil Aging on the Phytoremediation Potential of Zea mays in Chromium and Benzo[a]Pyrene Contaminated Soils.

This study compared the phytoremediation potential of Zea mays in soil either aged or freshly amended with chromium (Cr) and benzo[a]pyrene (B[a]P). Z. mays showed increased shoot biomass in aged soils than in freshly spiked soils. The shoot biomass in contaminated soils increased by over 50% in aged soil when compared to freshly amended soils, and over 29% more Cr was accumulated in the shoot of Z. mays in aged soil than in freshly amended soil. Planting Z. mays in aged soil helped in the dissipation of more than 31% B[a]P than in freshly spiked soil, but in the absence of plants, there seemed to be no difference between the dissipation rates of B[a]P in freshly and aged co-contaminated soil. Z. mays seemed to enhance the simultaneous removal of Cr and B[a]P in aged soil than in freshly spiked soil and hence can be a good plant choice for phytoremediation of co-contaminated soils.

Effects of Soil Aging on Mechanical and Hydraulic Properties of a Silty Soil

The aging phenomenon, which produces changes in material state over time, is associated with significant modification of mechanical and physical soil properties. This change should be accounted for during geotechnical design. Although soils sometimes improve with aging, the opposite effect is occasionally observed. This paper describes a study performed to investigate the effect of aging on the mechanical behavior and the permeability of a silty soil. Undrained unconsolidated triaxial shear tests and triaxial permeability tests were performed on disturbed and compacted samples. Upon conclusion of these tests, the samples were sealed from air and moisture. The results show an important increase in both the undrained shear strength and the deformation modulus caused by silt rigidification during the aging process. These changes cause an over estimation of laboratory measured shear strength. For instance, the increase in the deformation modulus and undrained cohesion can approach 100 % for an approximate 328 day storage period. Sample permeability was found to decrease with aging. This reduction can be ascribed to several causes including micro-organisms growth, secondary sample consolidation and progressive filling caused by the migration of very fine particles. These phenomena might have negated the expected increase in permeability with aging time reported in the literature.

Human health risk from arsenical pesticide contaminated soils: A long-term greenhouse study

Arsenic (As) bioaccessibility is an important factor in estimating human health risk. Bioaccessibility of As in soils is primarily dependent on As adsorption, which varies with residence time. This study evaluated the effect of soil aging on potential lifetime cancer risk associated with chronic exposure to As contaminated soils. Four soils, chosen based on their differences in As reactivity, were amended with two arsenical pesticides – sodium arsenate, and dimethylarsinic acid (DMA) at two rates (675 and 1500mgkg−1). Rice was used as the test crop. Soil was sampled immediately after spiking, after 6 months, 1 year, and 3 years. Bioaccessible and total soil As concentrations were used to calculate lifetime excess cancer risk (ECR), which decreased significantly with soil–pesticide equilibration time. Immokalee soil, with the least As adsorption capacity, showed the highest decrease in ECR after 6 months resulting in values lower than the USEPA's cancer risk range of 1×10−4 to 1×10−6. For all other soils, the ECR was much higher than the target range even after 3 years. In the absence of significant changes in As bioaccessibility with time, the total soil As concentration more directly influenced the changes in ECR values with soil aging.

Accumulation of Polybrominated Diphenyl Ethers, Hexabromobenzene, and 1,2-Dibromo-4-(1,2-dibromoethyl)cyclohexane in Earthworm (Eisenia fetida). Effects of Soil Type and Aging

In the present study the accumulation potentials in earthworms (Eisenia fetida) of selected brominated flame retardants (BFRs) were investigated. The tested BFRs, including polybrominated diphenyl ethers (PBDEs), hexabromobenzene (HBB), and 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH), were found to be bioavailable to Eisenia fetida, and they accumulated in the earthworms. To our knowledge, this is the first published study to address the bioaccumulation potential of TBECH in terrestrial biota. Aging the soil resulted in decreased accumulation of TBECH, HBB, and PBDEs with six or less bromine atoms. However, no effect of soil aging was seen for BDEs 183 or 209, possibly due to their low mobility in soil. The use of different soils (artificial OECD soil and two natural Swedish soils) also affected the degree of accumulation in the worms. The results indicate that use of the generally accepted standard OECD soil may overestimate accumulation of organic contaminants by earthworms, due to high bioavailability of the contaminants and/or weight loss of the worms in it. Further, the accumulation of selected PBDEs and HBB was compared to the accumulation of their chlorinated analogues. Brominated compounds accumulated to the same or a lesser extent than their chlorinated counterparts.

Effect of soil aging on arsenic fractionation and bioaccessibility in inorganic arsenical pesticide contaminated soils

Abstract Ingestion of As – contaminated soil by children is a growing concern in former agricultural lands converted to residential or recreational land use areas. The mobility and bioavailability of As is controlled by its reactions with soil particles. The degree and strength of As retention by soil constituents may vary greatly with time. The present authors hypothesize that aging results in reduced mobility of As thereby decreasing As release and its bioavailability. The present study is aimed at evaluating the effect of aging on soil As fractionation and bioaccessibility in a temperature and humidity-controlled greenhouse setting. The design allowed the evaluation of dynamic interactions between soils, pesticides, water, and plants. Therefore, 4 soil types (Immokalee, Millhopper, Pahokee Muck, and Orelia) were selected based on their potential differences in As reactivity. The soils were amended with the pesticide Na arsenate at two rates. Rice was used as the test crop. Soil samples collected after different time periods (0, 6 months, 1 a and 3 a) were extracted for soil-As forms via a sequential extraction technique. Bioaccessible As was extracted via an in vitro gastrointestinal method. At time 0, most of the extractable As in soil was in the soluble form, resulting in high bioaccessibility. As expected, soluble and exchangeable fractions decreased with time for up to 6 months, but remained constant thereafter. After 3 a of soil–pesticide equilibration, As bioaccessibility was still high in all the soils except for the Pahokee Muck. No significant difference in As bioaccessibility was observed between the soils. Arsenic was present predominantly as As(V) with 5–10% of the total dissolved As being present as As(III). Data obtained suggest that although aging had an impact on the geochemical forms, gastric pH was the sole important factor effecting As bioaccessibility.

The potential for bioaccumulation of tungsten in earthworms - the effect of legacy lead on biouptake

Studies have shown that the metal components in a soil influence the geochemical processes that occur in that soil (McGregor and Blowes 2002; Dermatas 2004; Petrunic and Al 2005). Since tungsten–nylon rounds have been fired on ranges that have historically been used for training using lead rounds, questions have been raised as to the effect that tungsten has on weathered lead and the other constituents in soils. Possible interactions with the various metals in the soil may affect tungsten’s solubility or sorption properties, which may in turn influence its bioavailability. In order to determine the effect of weathered lead on tungsten biouptake, a bioavailability study was conducted using earthworms (Eisenia fetida). This study allowed direct comparison of lead and tungsten biouptake in a variety of soils amended with weathered lead and fired on with tungsten–nylon bullets. The effects of soil aging on biouptake were also studied. Results indicate that changes in earthworm biouptake of lead and tungsten, which resulted from the presence of legacy lead (LL) material in soils, varied and were soil-type dependent. Soil aging generally did not affect the biouptake of lead or tungsten by earthworms.

Climate and soil‐age constraints on nutrient uplift and retention by plants

Plants and soils represent coevolving components of ecosystems, and while the effects of soils (e.g., nutrient availability) on plants have been extensively documented, the effect of plants on soils has received less attention. Furthermore there has been no systematic investigation of how plant effects vary across important ecological gradients in climate or soil age, which leaves a substantial gap in our understanding of how plant-soil systems develop. In this context, we analyzed changes in nutrient availability and elemental losses from the entire weathering zone at 35 sites arrayed across climatic and soil-age gradients on the island of Hawai'i. The sites are located on three basaltic lava flows (ages 10, 170, and 350 kyr) each of which crosses a precipitation gradient from approximately 500 to 2500 mm/yr. By comparing the loss of nutrient (potassium, phosphorus) and non-nutrient (e.g., sodium) rock-derived elements, we identify a climatic zone at intermediate rainfall where the retention of plant nutrients in the upper soil is most pronounced. We further show that there are several abiotic constraints on plant-driven retention of nutrients. At the dry sites (< or = 750 mm/yr on all three flows), plants slow the loss of nutrients, but the effect (as measured by the difference between K and Na losses) is small, perhaps because of low plant cover and productivity. At intermediate rainfall (750-1400 mm/yr) but negative water balance, plants substantially enrich both nutrient cations and P relative to Na in the surface horizons, an effect that remains strong even after 350 kyr of soil development. In contrast, at high rainfall (> or = 1500 mm/yr) and positive water balance, the effect of plants on nutrient distributions diminishes with soil age as leaching losses overwhelm the uplift and retention of nutrients by plants after 350 kyr of soil development. The effect of plants on soil nutrient distributions can also be mediated by the movement of iron (Fe), and substantial Fe losses at high rainfall on the older flows are highly correlated with P losses. Thus redox-driven redistribution of Fe may place a further abiotic constraint on nutrient retention by plants. In combination, these data indicate that the effects of soil aging on plant uplift and retention of nutrients differ markedly with precipitation, and we view this as a potentially fruitful area for future research.

混合汚れ洗浄性への統計解析の応用

In previous studies, statistical method using distribution of detergent power and that of resistance of soil against washing was applied to analyze detergency of oily soil and solid particle soil. In this paper, this method was applied to an analysis of detergency of mixed soil. Artificially soiled cloth prepared by aqueous dispersion method was used as a mixed soil sample. Four-time consecutive washing tests were conducted under the same washing condition in Terg-O-Tometer using two kinds of detergent solution and distilled water. Change of removal efficiencies due to repetitive washing was used to determine the two distributions. Result shows that detergent power can be expressed as cumulative distribution function. In washing simulation using the cumulative distribution functions, the predicted removal efficiencies corresponded with experimental values. Moreover, the effect of soil aging on distribution of soil resistance against washing was found to move the distribution curve toward high resistance. These results show that the method using two statistical distributions can be applied to the detergency of mixed soil.

Effect of soil wetting conditions on seal formation, runoff, and soil loss in arid and semiarid soils—a review

Soil surface sealing is one of the main causes for low infiltration rate (IR) and high runoff and soil loss under raindrop impact conditions in arid and semiarid regions. Many studies have focused on the effects of soil properties on seal formation under fast wetting conditions. However, in the field, soils can be exposed to different wetting conditions, before an intense rainfall event, which can affect the role of the soil properties on seal formation. The present paper reviews the effects of different initial wetting conditions and their interactions with soil properties on seal formation, IR, runoff, and soil loss in smectitic soils. Fast wetting of soil causes aggregate slaking, which enhances seal formation, runoff, and soil loss under rainfall, mainly in soils with &gt; 40% clay content. An increase in clay content of the soil increases aggregate strength, but at the same time increases the slaking forces. Hence, in soils with low clay content (&lt;40%) and low aggregate stability, raindrop impact alone was sufficient to break down the aggregates and to develop a seal. In contrast, in soils with &gt; 40% clay content and high aggregate stability, slaking plays an important role in aggregate breakdown and seal formation. An increase of raindrop kinetic energy, from 8 to 15.9 kJ/m3, decreased the effect of the slaking forces on seal formation and runoff. It was suggested that the effects of raindrop kinetic energy and of the slaking forces on aggregate disintegration and seal formation are complementary. An increase in soil exchangeable sodium percentage (ESP), from 0.9 to 20.4%, decreased the effect of slaking forces on seal formation and runoff production under rainfall with 15.9 kJ/m3 kinetic energy. Probably, increasing the ESP increased the soil dispersivity, and therefore diminished the effect of the slaking forces on aggregate disintegration and seal formation. Aging (the time since wetting) of soil increased the stability of soil structure, decreased the seal formation, maintained high IR, and diminished soil loss amounts. These effects of soil aging depend on both the prewetting rate of the soil and soil texture.

Effect of Soil Aging on Assessing Magnitudes and Accelerations of Prehistoric Earthquakes

Increase in strength due to aging of sands is reflected in higher blow counts and tip resistance values in penetration resistance measurements. This affects the magnitudes and peak ground acceleration estimates of prehistoric earthquakes obtained from an analysis of geotechnical observations at paleoliquefaction sites in the South Carolina Coastal Plain. In this study, corrections were made to account for the effects of soil aging, which were neglected in earlier estimates. The results show that when the effects of aging of soils on their geotechnical properties are incorporated, the resulting back-calculations reduced earlier magnitude estimates of prehistoric earthquakes by about 0.9 units. The peak ground acceleration estimates were reduced by about 15% for those earthquakes originally estimated at approximately 0.15 g. For those earthquakes whose original estimates were greater than 0.2 g, there was no noticeable change when a correction was made for the aging of soils.

Studies on the effect of soil aging on the toxicity of pyrene and phenanthrene to a soil-dwelling springtail

Soil samples spiked with five concentrations of pyrene and phenanthrene were aged for 0, 10, 40, and 120 d before toxicity was investigated using a standardized bioassay with the soil-dwelling collembolan Folsomia fimetaria L. Toxic effects were measured as reductions in survival and reproductive output after 3 weeks of exposure. Both pyrene and phenanthrene were degraded in the test system during storage, phenanthrene to a higher degree than pyrene. However, when toxic effects of the tested substances were calculated on the basis of measured concentrations of the parent compounds, toxicity was unaffected by storage for up to 120 d. Many studies have shown a negative correlation between aging and the biodegradation of polycyclic aromatic hydrocarbons (PAHs), indicating a reduction in the bioavailability of PAHs to micro-organisms with time. Our results indicate that a reduction in toxicity, as related to the measured concentrations of the parent compounds in the soil, may not always be expected for aged soils. Provided that metabolites of pyrene and phenanthrene did not significantly contribute to the toxicity in aged soil samples, a possible explanation for the absence of aging effects is the high test concentrations used in combination with the low content of organic carbon (1.6%) in the test soil.

Effects of soil ageing on the accumulation of hydrogen sulphide and metallic sulphides in mangrove areas in Singapore

The effects of soil ageing on the accumulation of hydrogen sulphide and metallic sulphides were studied in reclaimed mangrove plots of increasing ages. The analysis was carried out using a low-cost electrochemical approach, utilizing a sulphide volatilization/trapping procedure followed by sulphide quantification with an ion-selective electrode technique. The results showed that the content of hydrogen sulphide in the soil increased with age. Initially, the content of metallic sulphides also increased with the age of the soil. However, once the supply of metallic soil components for sulphide precipitation had been exhausted, the sulphides generated in the soils existed as hydrogen sulphide. The reasons for these patterns of sulphide accumulation in the mangrove soil and their possible impact on the growth of different types of mangrove vegetation are briefly discussed.

Cadmium soil sorption at low concentrations: II. Reversibility, effect of changes in solute composition, and effect of soil aging

Desorption of Cd from two Danish soils (loamy sand, sandy loam) previously exposed to low concentrations of Cd was examined in terms of reversibility, effect of changes in solute composition, and effects of aging of the soils for extended time prior to accomplishing the desorption experiments. The loamy sand exhibited full reversibility of Cd sorption in 10−3 M CaCl2 at pH = 6.0, while the sandy loam at the same conditions exhibited a partial irreversibility of the order of 1 μg Cd g−1 soil. However, this partial irreversibility was not caused by any strong binding of Cd since no irreversibility was observed in 10−2 M CaCl2 at the same pH. Changing the solute composition with respect to Zn, CaCl2, pH and the presence of organic ligands (EDTA) caused significant desorption of Cd from the soils. The degree of desorption was proven with respect to variations in CaCl2 and pH to be governed by the sorption equilibrium conditions independently of the previous distribution of Cd between soil and solute. Aging of the soil at a temperature of 1 °C (after exposure to Cd) for 35 and 67 wk did not reveal any changes with respect to desorption of Cd at pH = 6.0 in 10−3 M CaCl2.