Journal of Soils and Sediments最新文献

Purpose

Agitation dredging has gained popularity as an environmentally friendly and cost-effective method for port maintenance. One of the advantages of agitation dredging is the ability to transport sediments out of the port area using natural currents. The effect of the different agitation methods on sediment and water properties has rarely been investigated in a single pilot project. This research aims to study the effects of agitation methods in silt and sand-dominated areas that are frequently maintained.

Methods

The effects of water injection dredging, (WID) underwater ploughing (UWP) and Tiamat on sediment properties are investigated in the Port of Rotterdam. In-situ measurements and laboratory measurements are carried out to determine changes in the bed level, the particle size distribution of the bed, the turbidity in the water column and the dispersion distance of the sediment plume due to agitation dredging.

Results

The results of the in-situ monitoring of the agitation pilots allow a comparison of the changes in sediment and water properties before, during and after agitation dredging. The production, advantages and limitations of the tested agitation dredging methods are discussed.

Conclusion

The in-situ measurements show that WID, Tiamat and UWP can be successfully used for the agitation of sediments and their removal from the silt and sand-dominated areas. The production of the tested agitation methods is higher for silty than sandy sediments. In general, the selection of the agitation equipment can be made based on environmental regulations, sediment properties and hydrodynamic conditions.

Purpose

In order to investigate the desorption effect and mechanism of petroleum from petroleum contaminated soil (PCS) in surfactant solution (SAA-solution).

Method

In this study, the desorption effect of SAA-solution cleaning of PCS was systematically analyzed by using orthogonal experiments. In addition, the petroleum mechanism of desorption from the PCS surface was further explored by kinetic and thermodynamic studies.

Results

The results indicated that the petroleum removal efficiency (Re) gradually decreased with the increase of PCS particle size and PCS aging time. The highest petroleum Re was 82.13% under optimum conditions. Subsequently, FT-IR and petroleum component analysis showed the petroleum light components were easily removed from PCS, while the petroleum heavy components limited the desorption of petroleum. The kinetic studies revealed that the petroleum desorption was well depicted by the pseudo-first-order kinetic model, and the desorption rate increased with the decrease of PCS particle size. Meanwhile, the petroleum desorption equilibrium was well described by the Langmuir isotherm model and proceeded by a chemical mechanism. The thermodynamic studies demonstrated that the petroleum desorption from PCS was a viable, spontaneous, and endothermic process.

Conclusion

The study provided theoretical guidance to apply SAA-solution cleaning industrial PCS.

Graphical Abstract

Purpose

The aims of this research were to assess the sources of variability of particulate FRNs (⁷Be, ²¹⁰Pb_ex and ¹³⁷Cs) in river channels, the influence of sediment properties such as particle size distribution (PSD) and organic matter (OM) on FRN distributions, and to discuss the implications for sediment tracing in rivers.

Methods

Suspended and channel bed sediment samples were collected in the River Avon (Devon, UK) during five strategic surveys involving a wide variation of river flows, including flood conditions. Particulate matter was analysed for ⁷Be, ²¹⁰Pb_ex and ¹³⁷Cs by gamma spectrometry, PSD by laser diffraction, and organic constituents, total organic carbon (TOC) and total nitrogen (TN) by elemental analysis.

Results

FRNs activity concentrations vary significantly both spatially, characterised by changes in activity concentrations within and between locations, and temporally, with changes during the storm hydrograph and between seasons. Variability was attributed to changes in sediment sources and, on some occasions, to significant correlation of activity concentrations with sediment properties. The results also highlighted the influence of changes in channel characteristics and the magnitude and frequency of floods on FRN distributions.

Conclusion

In the context of sediment tracing, attention should be given to seasonal changes in riverine conditions that have the potential to affect ⁷Be and ¹³⁷Cs conservativeness. Application of FRNs in sediment fingerprinting studies should be accompanied by appropriate temporal characterisation of potential sediment sources. Finally, potential contribution of ⁷Be-depleted sediment from channel resuspension to the suspended load should also be considered.

Purpose

Understanding spatial variations in soil nutrients and its drivers is essential for sustainable nutrient management and related environmental assessment in terrestrial ecosystems. Here, we investigated the distribution characteristics and controlling factors of soil total nitrogen (N) and N fractions along an altitude gradient in an alpine meadow of the Qinghai-Tibet Plateau.

Materials and methods

Six experimental sites at altitudes 4400, 4500, 4650, 4800, 4950, and 5200 m were established on southern slope of Nyainqentanglha Mountain since 2005. Total N and N fractions were quantified and their relationships with climate, vegetation, and edaphic factors were analyzed by Pearson correlation, redundancy analysis, and structural equation modeling.

Results and discussion

With increasing altitude, the contents of total N, alkali-hydrolyzable N, inorganic N fractions (ammonium N and nitrate N), and organic N fractions (acid-hydrolyzable and acid-insoluble organic N) gradually increased, reached their maximums at altitude 4800 or 4950 m, and then decreased. Soil organic carbon explained 90.5% of the variations in TN and N fractions, and soil moisture, pH, mineralogy, texture, and N hydrolyzing enzyme activity explained 8.80% of the variations in TN and N fractions. Mean annual temperature and precipitation exhibited direct and positive impact on soil organic carbon, which had positive effect on inorganic N fractions and plant aboveground biomass in sequence.

Conclusions

Soil organic carbon is the most dominant factors driving the variations in TN and N fractions along the altitude gradient. Climate change can impact alpine grassland productivity by regulating soil inorganic N distribution.

Purpose

Rare Earth Elements (REEs) are becoming more present in our everyday life. With this work, we aimed to study and compare the toxic responses of the REEs lanthanum (La), cerium (Ce), neodymium (Nd), and gadolinium (Gd) to the macrophyte Myriophyllum aquaticum. The scope was to evaluate if these elements trigger a response on the photosynthetic system (PSII), which causes inhibition of the growth rate of the plant.

Methods

We measured the fluorescence yield by pulse-amplitude-modulated chlorophyll fluorometer (PAM) which enabled simultaneous high-resolution fluorescence measurements of the whorls daily for the whole duration of the test (10 days) and fresh weight change (FWC) at the end of the test.

Results

Our findings suggest that La significantly decreased FWC at the highest concentration (500 mg kg⁻¹) but did not cause any significant effects on the fluorescence yield. Ce and Nd significantly decreased the chlorophyll fluorescence between days 2 and 4, and after that the yield was not significantly different with respect to the control. Of all the REEs tested in this study, Gd showed the most negative effect as the whorls exhibited chlorosis/necrosis and the fresh weight at the end of the test decreased significantly compared to the same plant at day 0. The yield of M. aquaticum showed time-dependent effects for Gd at the highest concentration.

Conclusion

Gd was the most toxic REE, strongly affecting both the yield and FWC. The measurement of the fluorescence yield of the PSII is a useful effect observation and of high environmental importance. The difference in sensitivity between the functional and growth endpoints may give hints about the mode of action of contaminants to aquatic plants.

Purpose

Death is inextricably linked to the functioning of the biosphere, including the presence of humans on Earth. The remains of 117 billion people who have ever lived on Earth are mostly hidden in the soil. Hence, the organization, use and subsequent fate of cemeteries and their surroundings should also be considered from the perspective of pedeogenesis. The soils of such areas are subject to multifactorial human pressure, as reflected in their often complex soil profiles.

Materials and methods

The situation of a Central European city of medieval origin, Zielona Gora (Poland), characterized by the presence of 39 cemeteries within its current boundaries, is presented. The location of these cemeteries was shown in light of other factors of human pressure on soil, including relation to buildings construction and a land use. The analysis of the current form of use of burial sites and their immediate surroundings used the technique of field research and a city's documentation query. In order to reflect the specific impact of the form of use of post-burial grounds on soil properties, selected soil characteristics of exemplary historical cemeteries are presented. The main soil characteristics were evaluated using standard methods of laboratory analysis.

Results and discussion

Some cemeteries are reflected in the city's planning documents – there are all contemporary cemeteries and a few historical ones. The vast majority of historical burial sites are not reflected in the plans. This makes modern urban development directly adjacent to them and even encroaches on their territories. Soil analysis has shown that human remains are still present in soils of these areas, even hundreds of years after cemetery closure. In addition to these, the soils are characterized by elevated C and P content relative to the bedrock. The arrangement of the necrosol profile is disturbed by the significant presence of construction and municipal waste. The most soil characteristics, including grain-size composition, pH, EC, sorption properties, organic and inorganic carbon content, as well as macronutrients and heavy metals, are strong influenced by the land use form and urban pressure on cemetery areas.

Conclusions

It is common practice around the world to bury human bodies or ashes in soil, hence their remains contribute to soil profiles. Proper identification of cemetery soil profiles, with a clear indication of necric features, is difficult due to the different uses of cemetery land. The soils of former cemeteries, by reason of their relationship to buildings and urban parks, take on the characteristics typical of such urban land use forms.

Purpose

Manganese (Mn) is crucial in low concentrations but can become toxic in soils and sediments, affecting plants and animals. Understanding how plants inoculated with arbuscular mycorrhizal fungi (AMF) tolerate Mn is crucial for the application of these microorganisms in the remediation of contaminated soils. Despite recognized benefits in various plant species, assessing plant-AMF interaction effectiveness in mitigating Mn toxicity is crucial for undocumented plants.

Methods

Acacia mangium Willd. plants were inoculated with an AMF native to a Mn mining area and grown in soil with increasing Mn levels (0, 200, and 400 mg kg⁻¹) to evaluate the effects of inoculation on plant growth and plant-AMF association strategies to reduce Mn toxicity.

Results

Inoculation with AMF resulted in beneficial effects, minimizing Mn toxicity and enhancing plant growth, despite reduced mycorrhizal colonization and AMF spore levels in the soil. Non-inoculated plants exposed to 400 mg kg⁻¹ of Mn exhibited significant reductions in shoot dry mass (64.9%), number of leaves (25%), and root length (24%) compared to AMF-inoculated plants. Mn concentration was higher in the roots of AMF-inoculated plants at all Mn levels, indicating a restriction in Mn transport to the shoot, thus minimizing damage and promoting plant growth. Energy-dispersive spectroscopy identified Mn, potassium, phosphorus, iron and calcium in AMF spores, suggesting their protective role against Mn phytotoxicity and adaptability of this species of microorganism under stress conditions.

Conclusion

The native AMF inoculation reduces toxicity and improves the growth of A. mangium Willd. under high levels of Mn in the soil.

Purpose

Since the occurrence of humans, soil has been affected by them. Thus, rural areas have been modified. Currently, urban areas are increasing extensively. They are locations with a high population density that are impacted by settlements and industrial technologies. This paper shows how soils are further discriminated by urbanization.

Material and methods

A collection of observations and conclusions about the characteristics of natural and urban soils and the discrimination by interpretation of the particularities of discovered soils are presented. This view is enlarged by the specific features of the mode of human action and their effects on soil formation.

Results and discussion

The effects of humans on soils in rural areas are numerous. They concern effects from soil use, evolving soil fertility and raw material supply by mining. Changes in soil formation occur due to natural factors in the landscapes. Discussions about the nature of soils in urban areas stress the situation of a low soil age, that they become relicts, are highly disturbed, contain artifacts, and are mostly byproducts of human decisions. Based on the specific urban climate, there are zonal soils. Perceptions about what qualifies these soils to be separately designated as urban soils are presented. The new view of the differentiation of artifacts by their origin from heat-treated products allows a more precise definition of soils in urban areas. Soil formation can occur quickly.

Conclusion

Urban soil research is a wide field for discovering new modes of soil formation and the relationship between humans and soils.

Purpose

Accurately assessing soil moisture content (SMC) is essential for applications in agriculture and ecological sustainability. However, the dynamic monitoring and assessment of SMC presents considerable challenges due to the intricate traditional methods and the ever-evolving environmental variables. Relevant research has indicated that visible and near-infrared (vis–NIR) spectra are a practical and cost-effective alternative for accurate and convenient estimation of SMC. Advances in technology and computer hardware have enabled spectral characteristics and computer vision algorithms to show enormous potential for rapid and non-destructive characterization of soil properties. The objective of this study was to evaluate the predicted ability of SMC using vis–NIR spectral data.

Materials and methods

A total of 60 topsoil samples (0–5 cm) from the maize test field at the Shanxi Central Irrigation Test station were used as the study object. A set of four spectral parameters was derived and filtered from spectral data, and C-W and W-W models were developed using Genetic Algorithm algorithm-optimized backpropagation (GA-BP) neural networks to predict SMC based on outdoor measurements.

Results and discussion

The results showed that: (1) SMC can be successfully predicted using the spectral data through the C-W and W-W models; (2) the C-W model outperformed the W-W model, particularly in the context of deep soil, with R² ranging from 0.919 to 0.991 and corresponding RMSE values from 0.619% to 0.982%.

Conclusions

This study introduces two effective methodologies for accurate estimation of SMC at different depths using multispectral remote sensing, which showed a high degree of prediction accuracy. It further proves that GA-BP algorithm is still effective for predicting SMC in outdoor. The research result might be helpful for the further study of SMC measurement.

Purpose

The main factors governing iron-bound organic carbon (Fe-bound OC) formation under different environmental conditions have been less well identified. In this study, we investigated the distribution of Fe-bound OC and the influencing factors in soils of a typical subtropical mountain ecosystem.

Materials and methods

Soil samples at different altitudes (402–1653 m) and depths (0–20 cm, 20–40 cm, and 40–60 cm) in the Nanling Mountains of southern China were collected. The influence of soil property indicators and microbial diversity characteristics on the formation of Fe-bound OC was explored.

Results

The Fe-bound OC content in the soils ranged from 1.40 ± 1.32 g/kg to 15.09 ± 3.57 g/kg, accounting for an average of 23.49 ± 13.03% of the total organic carbon (TOC), and generally increased with altitude and exhibited significantly higher values at the soil depth of 0–20 cm, while its proportion to TOC (f_Fe-OC) gradually increased as soil depth increased. The more significant indicators in explaining the variation of Fe-bound OC include TOC, particulate organic carbon (POC), free iron oxides (Fe_d), amorphous iron oxides (Fe_o), complexed iron oxides (Fe_p), Fe_o/Fe_d, pH, Ca, sand and silt. Fe_o/Fe_d was strongly linearly correlated with Fe-bound OC, thus can be a good predictor of Fe-bound OC content. RDA analysis showed that Fe-bound OC/f_Fe-OC had a relatively closer correlation with bacterial phyla including Proteobacteria, Actinobacteriota, Chloroflexi and Firmicutes.

Conclusions

The attitude gradient and soil depth significantly influence the content of Fe-bound OC. The distribution of Fe-bound OC exhibited a certain correlation with both biotic and abiotic factors.