Journal of Soils and Sediments最新文献

Purpose

The turnover of organic phosphorus (P_o) may be an important way to maintain P supply for plant growth under the phosphorus (P) deficiency in highly weathered tropical soils. However, there is limited information on P_o change pattern and how abiotic and biotic factors influence P_o transformation in tropical region. Thus, this study was aimed to the characteristics and controls of P_o transformation towards the advanced stage of tropical soil evolution.

Methods

A well-establish tropical soil chronosequence (0.09, 0.146, 0.64, 1.12, 1.81, and 2.30 million years) derived from basalt in northern Hainan Island, China, was selected and the P_o compounds in all soils determined by solution ³¹P nuclear magnetic resonance spectroscopy.

Results

Phosphate monoester showed a rapid increase in the earlier stage of pedogenesis (< 0.15 million year), thereafter declined to the minimum in the 1.12-million-year site and fluctuated in older soils. Meanwhile, the proportion of labile P_o (including phosphate diester and its degradation products) increased continuously across the chronosequence, suggesting that long-term tropical soil evolution promoted labile P_o accumulation that was vital to maintain P supply in highly weathered and P-deficient soil. Redundancy analysis revealed that P_o transformation was jointly affected by soil total nitrogen, total organic carbon, phytase, and amorphous iron, accounting for 37.5% (p < 0.01), 29.5% (p < 0.01), 20.7% (p < 0.05), and 14.8% (p < 0.05) of explanation in the variations of P_o compounds, respectively.

Conclusion

Our study has supplemented the blank of P_o transformation during tropical soil evolution over a 2.30-million-year time scale and emphasizes the important role of soil C, N in regulating P_o changes.

Purpose

The study of microplastics (MPs) in soils is one of the most important contemporary challenges as they negatively influence soil properties and may adsorb heavy metals and pesticides. Recent data show that they can be transported in the terrestrial food chain, endangering human and animal health. In this pilot study, the qualitative–quantitative analysis of microplastics in soils of allotment gardens, which are mainly used for fruit and vegetable production, was done. Also, sources and environmental risks related to microplastics are discussed.

Methods

We applied a four-step approach based on standard soil characteristics, density separation of MPs from the soil matrix, stereoscopic microscopy, and Fourier infrared spectrometry (FTIR).

Results

In all studied topsoils, high abundance and heterogeneity of microplastics were found. Microplastics like polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC), polyurethane (PUR), phenolic resins (PF), and alkyd resins (AR) were identified. Their sources are not only related to human activities on the allotments, but also deposition with wind or water cannot be excluded.

Conclusions

We revealed that soil contamination of microplastics in allotment gardens can be a significant environmental problem that has been overlooked in research. Considering the high amount of people who use allotment gardens and the potential environmental risk, soil contamination by microplastics should be monitored.

Purpose

Tillage practices and crop growth play important roles in the soil erosion of sloping farmland. This study aims to investigate the effects of tillage practices on soil erosion in response to different crop growth stages and to determine the primary factors that affected the runoff reduction benefit of tillage practices among different growth stages.

Methods

A field study was carried out under natural rainfall conditions, and 12 runoff plots (20 m × 5 m) were established, including four treatments, i.e., flat planting (FP), flat planting with hedgerow intercropping (HG), longitudinal ridge (LR) and bare land (CK). Runoff and soil losses after each rainfall event were monitored during the peanut seasons of 2021 and 2022 and the effects of tillage practices and peanut growth stages on runoff and sediment yields were evaluated.

Results

The total surface runoff depth and sediment yield decreased in the following order: CK > LR > FP > HG. As peanuts grew, the seedling, needling, podding, and full fruit stages contributed approximately 71.5%, 20.4%, 6.4%, and 1.7% of the total runoff depth, respectively, which could be attributed to the synergistic impact of rainfall, crop growth, and antecedent soil moisture. During the seedling stage of peanuts, which did not provide sufficient surface cover, concentrated rainfall in large amounts resulted in high soil moisture and consequently high runoff losses. As peanuts grew, the S-shaped growth curve for peanut aboveground parts and root systems and reduced rainfall depth and frequency resulted in less runoff loss and increased runoff reduction benefits of tillage practices.

Conclusions

The early growth stage of peanuts, generally accompanied by high antecedent soil moisture and heavy rainfall, should attract more attention to improving water erosion conditions on sloping farmland with only longitudinal ridges.

Purpose

Soil contamination and solid waste accumulation pose significant risks to the safety of agricultural produce and residential areas. In China, coal gangue, a typical form of solid waste, is rich in valuable elements like silicon and aluminum, making it an ideal precursor for the synthesis of zeolite molecular sieves. This study focuses on transforming coal gangue into iron-enhanced X-type zeolite (Fe-NaX) molecular sieve and explores its potential in remediating lead (Pb) and cadmium (Cd) co-contaminated soil.

Methods

Fe-NaX was synthesized from coal gangue in Sichuan using an alkaline melting hydrothermal method. In order to evaluate the effectiveness of Fe-NaX in remediation and assess its ecological risk, soil culture and acid rain leaching experiments were conducted. The microstructures of Fe-NaX were detected to explore its remediation mechanism.

Results

The optimal Fe-NaX was synthesized at a 110 °C hydrothermal reaction temperature, a 1.5 mass ratio of NaOH and pretreated coal gangue (PCG), a 2.0 Si/Al molar ratio, and a 3.5 M alkalinity. Fe-NaX demonstrated outstanding performance in remediating Pb and Cd contaminated soil, with immobilizing efficiency for high bioavailability fractions of Pb and Cd at 44.4% and 21.9%, respectively. Even under acid rain stress, Fe-NaX was able to decrease the release of Pb and Cd in the soil by 42.3% and 59.6% respectively, with minimal ecological risk.

Conclusion

This study, based on a “solid waste for soil-remediation” strategy, transforms coal gangue into Fe-NaX for use in soil remediation and holds great promise for the contaminated soil remediation and coal gangue comprehensive utilization.

Graphical abstract

Purpose

The competitive sorption of arsenite, As(III), and antimonite, Sb(III) on mackinawite (FeS) was investigated, so as to better understand the influence between As(III) and Sb(III) in anaerobic water, soil, or sediment systems rich in FeS.

Methods

FeS was synthesized and As(III) and Sb(III) were simultaneously or sequentially added into the FeS suspensions, so as to simulate the competitive sorption of As(III) and Sb(III) on the surface of FeS particles when As(III) and Sb(III) were parallelly sorbed or As(III) sorption was priorly aged.

Results

It was found that As(III) uptake by FeS could be significantly inhibited by Sb(III) at pH 7.0. When As(III) (initial concentration: 1 mg L⁻¹) and Sb(III) were simultaneously added into FeS suspensions at pH 7.0, the presence of Sb(III) reduced the As(III) uptake by FeS from 51.8% (no Sb(III) added) to 22.7% (1 mg L⁻¹ Sb(III) added) and to 6.9% (5 mg L⁻¹ Sb(III) added), respectively. In contrast, As(III) uptake by FeS was only slightly inhibited at pH 5.5 and not inhibited at pH 9.0. It was postulated that the competitive sorption of As(III) and Sb(III) was primarily associated with the binding of As(III) and Sb(III) to FeS at the sulfur sites and the different chalcophility of Sb(III) and As(III) led to the significant replacement of As(III) by Sb(III) at pH 7.0. It was also found that aging of As(III) sorption significantly reduced the amount of As(III) that was outcompeted by Sb(III).

Conclusion

This study revealed the competitive sorption of As(III) and Sb(III) on FeS particles, and implicated the importance of competitive sorption in evaluating the mobilization or immobilization of arsenic or antimony in iron- and sulfur-rich anaerobic lake sediments or soils.

Purpose

Pejão Mining Complex locates in Castelo de Paiva municipality and, until its closure in 1994, was one of the most important coal mines in the Douro Coalfield. This work aims to study the presence, quantify, and evaluate the dissemination of mercury (Hg), a potentially toxic element (PTE) of major public health concern by the World Health Organization (WHO), from a waste pile affected by coal fires.

Materials and methods

Samples from areas affected and unaffected by the combustion and from surrounding soil were collected from Fojo waste pile region. First, the Hg pseudo-total concentration was estimated for all collected samples by soil microwave–assisted digestion with aqua regia (USEPA 3051A). Then, a sequential extraction procedure (SEP), the USEPA 3200, was applied for Hg fractionation and speciation aiming to evaluate Hg mobility and bioavailability to surrounding ecosystems.

Results and discussion

The results obtained showed a Hg enrichment in soil samples when compared to Portuguese and international reference values for soils. Relatively to the Hg availability and mobility, although it predominates in the semi-mobile fraction, the waste pile materials exposed to combustion showed a concerning increase of Hg levels in the mobile fraction that contains the more labile Hg species, being a major source of environmental contamination by Hg.

Conclusions

This study allowed to conclude that combustion of mining residues increased Hg mobility, toxicity, and bioavailability, increasing the contamination potential of the coal waste pile. The methodology applied in this work can be replicated in other abandoned mines to monitor, control, and/or mitigate the Hg environmental impact in the surrounding soils and waters.

Purpose

Climate change, largely caused by elevated carbon dioxide (CO₂) concentrations, is a driver of lasting disturbances that cause changes in forest ecosystem functioning. This study aimed to investigate how Japanese cypress (Chamaecyparis obtusa) and Japanese cedar (Cryptomeria japonica D. Don) plantations in the subtropical forests of China respond to disturbances in tree growth under climate change.

Materials and methods

In this study, 23 canopy gaps were selected from two species in the Lushan National Nature Reserve of Jiangxi Province, China. Increment cores were obtained from trees retained near the edges of gaps and within the forest. Tree-ring chronologies were established, and the basal area increment (BAI) was calculated. The growth averaging method was used to detect growth release and analyze two key parameters of tree radial growth: magnitude and time lag. Moving correlation analyses were used to assess the long-term relationship between tree growth and climate, and regression analyses were used to quantify the relationship between the BAI and atmospheric CO₂ concentrations.

Results and discussion

Species characteristics, tree distance from the gap center, gap size, and elevation all influenced tree growth release which was greater for Japanese cedar than Japanese cypress, and decreased with increasing distance from the gap center. Diameter at breast height (DBH) and pre-release growth influenced the time lag in growth release. The time-lag effect was more significant with smaller DBH and pre-release growth and did not differ between the two species. The correlations among growth, temperature, and precipitation were altered by the microclimatic environment created by the gaps. The BAI of Japanese cypress and Japanese cedar responded quadratically with increasing CO₂ concentration (C_a), and the BAI increased with rising C_a, peaking at 360–380 ppm, followed by a decreasing trend. Due to the effect of the disturbance, there was a BAI increase of approximately 400 ppm (2015) for trees at the gap edge.

Conclusions

Growth characteristics were influenced by tree- and gap-level variables. Disturbance altered the link between tree growth and climate responses, increasing tree growth sensitivity to climatic influences, shifting the quadratic relationship between BAI and CO₂ concentration, and providing growth potential to trees that crossed the CO₂ tipping point.

Aortic dissection is rare and often presents with atypical symptoms. We describe a case of a patient with acute aortic dissection involving the coronary arteries, complicated by pericardial tamponade, and discuss findings using point-of-care ultrasound, diagnostics, and treatment of this condition.

Abstract

Purpose

Identify soil properties involved in the adsorption of the bacteriophages (phages) ΦITL-1 and ΦRSP, analyzing different soils and substrates used for greenhouse tomato crops.

Methods

Soil samples were collected from greenhouses in Mexico Central, and soil properties were obtained using the NOM-021-RECNAT-2000. For phage adsorption, soil or substrate was mixed with a phage solution, using three different Water Retention Capacity (WRC) levels, incubated under shaking to room temperature, and finally, the plaque-forming units were counted for each phage by titration.

Results

The phage elution counts showed that the amount of aqueous solution in the mixture is inversely related to the number of viral particles adsorbed on the soil. Furthermore, the soils with a sandy texture had lower adsorption of phages in comparison with the rest of the soils analyzed, which have clay, clay loam, and sandy loam textures. A correlation analysis showed that soil pH and texture are the properties that most influenced phage adsorption. Finally, a principal component analysis showed that Cation Exchange Capacity (CEC) has a direct relationship with phage adsorption.

Conclusion

In the present study, we demonstrated that soil texture, pH, CEC, and WRC are determinant variables that affect the adsorption of R. solanacearum phages ΦITL-1 and ΦRSP. Furthermore, we propose that the responsible mechanism may be due to the richness of cations in the soil, which could imply an electrostatic interaction with some exposed phage proteins. These results highlight the influence of soil properties on biocontrol strategies based on phages, which try to reduce the impact of soil-borne bacterial phytopathogens.