Journal of Soils and Sediments最新文献

Purpose

Mining has been carried out in San Luis Potosi, Mexico, since 1592, which has led to severe pollution issues affecting both the environment and human health. To address this, remediation projects have been initiated to restore the soil and its ecosystem services. These efforts involve removing the contaminants and restoring the soil’s health and quality. This study aims to assess the biochemical impact of soil remediation carried out in the field, on areas that have been heavily contaminated with heavy metals over a prolonged period.

Methods

The enzymatic activity, physiological profile, structure, and microbial diversity were used as bioindicators to assess the remediation of soil and two reference soils.

Results

The results indicated that Pb and As decreased, but not at levels indicated by Mexican regulations, Cd concentrations decreased to be below Mexican regulations, the enzymatic activity between the soil with and without remediation did not present significant differences, both with low activity, arylsulfatase was the one with the highest inhibition, and urease the most activated. The evolution of the physiological activity of the microorganisms was greater in the remediated soil. Normal values of evenness and diversity were observed in soils with and without remediation, likewise, the consumption of substrates initially was towards carbohydrates and amines/amides, but in the end, carboxylic acids and polymers were consumed.

Conclusion

The remediation process shows positive results; the recovery of soil health is in progress. It was demonstrated that the bioindicators used were adequate to evaluate the soil remediation process.

Abstract

Purpose

This study aims to assess the spatial distribution of carbon reserves in the surface of organic and mineral soil layers, in a carbon landfill. The studied areas are located within the broad-leaved forests of the Southern Urals.

Methods

The analysis of the forest carbon cycle was conducted in early spring on trees, shrubs, and grass vegetation. Soil gas flux measurements were performed using a Smart Chamber connected to a LI-COR 7810 gas analyser. CO₂ flux emission from the soil surface reached up to 493.2 G_f a day, under the tree canopy and did not exceed 471.8 G_f in uncovered areas (glades).

Results

Thus, in early spring, the CO2 flux emissions from the soil surface in forest stands is higher in absolute terms, than in uncovered areas. It can presumably be explained by the difference in vegetation cover, along with the size, depth, and spatial distribution of roots from trees, shrubs and herbaceous plants.

Conclusion

Forest litter and humus, mainly composed of potassium, nitrogen, and phosphorus, are critical for maintaining the carbon balance in forest areas.

Purpose

The Buenavista del Cobre mine is in a semiarid environment in NW Mexico. A part of the mine tailings dam has been flooded with wastewater from Cananea, generating an artificial wetland. The main objectives of this work were to evaluate the effect of wastewater on the pedogenesis of wetland Technosols developed on mine tailings and to compare them with the soil of non-irrigated tailings and with a natural soil profile.

Materials and methods

Three profiles were studied inside the dam as follows: a profile under waterlogging conditions, a profile under conditions of periodic sewage saturation, and a profile with no waterlogging conditions. Laboratory methods included the micromorphological analysis of the soil structure and pedo-features, fertility properties, identification of clay minerals, and analysis of bulk chemical composition.

Results and discussion

It was found that the biogenic structure and voids associated with organic materials were the main micromorphological features of the studied wetland Technosols. Primary sulfides remained unaltered in the Technosols irrigated with wastewater, whereas incipient sulfide oxidation was observed in the non-irrigated tailings. Chlorite and smectite were detected in the Technosols. Such mineral assemblage was found to be mostly generated by hydrothermal processes.

Conclusion

Irrigation of tailings with wastewater supported the biological aggregation and porosity formation within the soil matrix, supplied plant nutrients, and enhanced the ecological soil quality of the studied hydromorphic Technosols. Saturation with wastewater hampered the oxidation of primary sulfides in the hydromorphic Technosols, preventing soil acidification and the mobilization of heavy metal contaminants.

Purposes

This research focuses on the characterization of phosphate ore, its solid effluents, and nearby contaminated soils in the southwest Tunisia (Gafsa-Metlaoui Basin). It aims also at evaluating the vertical distribution and abundance of critical rare earth elements (REE) in the different materials and their ecological and environmental risks.

Materials and methods

The sampled materials went through physical, chemical, and mineralogical characterization which involved XRF, XPS, XRD, and ICP-MS analyses. The REE anomalies and the environmental and ecological indices were calculated.

Results and discussions

Results show relatively high concentrations of nine rare REEs, following the sequence La > Ce > Nd > Y > Gd > Eu > Sm > Yb > Tb and trace metal elements (TME) such as Cd, Cr, Mn, Zn, Co, Fe, Sr, Cu, Ni, Pb, Ba that surpass, in some cases, international standards. The vertical distribution of the studied elements within a sediment, tailings, and soil profiles (beyond 20 cm of depth) indicates their likely in-depth migration. TME- and REE-bearing phosphate samples reflect mostly oxic conditions in the southern area with high positive Eu anomalies signifying possible mixing of sources. The environmental assessment indicate no contamination and a moderate enrichment of REEs, except for Eu, which displays significant contamination and extreme enrichment. Whereas, a deficiency of Y has been detected in most of the studied samples except for sludge sample which was also found significantly enriched with REE.

Conclusions

There are fundamental similarities between the different studied samples with high carbonate mineral concentrations. Statistical analysis confirmed the spectroscopic fingerprints demonstrating that the different materials share a similar composition. All of these similarities are most likely linked to the impact of mining activities on sediments and soils. Overall, our findings highlight the global effect of ore processing in determining the geochemical and the mineralogical characteristics of the surrounding environments of mines.

Purpose

Brazilian territory is divided into six biomes (Amazon, Atlantic Forest, Cerrado, Caatinga, Pantanal, and Pampa) that represent important global biodiversity hotspots. Research into soil science in these environments has increased in recent years, but a quantitative and qualitative mapping of research into the soils of Brazilian biomes has never been carried out. In this study, research on soil science in the Brazilian biomes were analyzed to map the evolution, scientific collaboration, current status, research trends and impact over the last 50 years (1972–2022).

Methods

The database was obtained from the Core Collection of Web of Science. The data was quantitatively analyzed through descriptive statistics and linear regression using Microsoft Excel, and qualitatively using the bibliometric software VOSviewer.

Results

A total of 11,231 papers were obtained. The results indicated a significant increase in soil science research across all biomes (polynomial growth), with greater emphasis for research in the Cerrado (R² = 0.9361), Amazon (R² = 0.9170) and Atlantic Forest (R² = 0.9104) biomes. Soil science research in the Amazon accounted for 47.0% of the research conducted in all Brazilian biomes. While in the Amazon (38.8%), Atlantic Forest (34.8%), and Pantanal (36.7%), most of the research was related to environmental sciences and ecology, in the Cerrado (47.4%), Caatinga (58.2%), and Pampa biome (48.9%), research in the field of agriculture was more significant. For all biomes, except for the Caatinga (a dry climate biome), a significant participation of international researchers and institutions was evident in the overall publications. This demonstrates a lower global interest in soil science research in the Brazilian dry ecosystem.

Conclusion

Soil science research in the Brazilian biomes is disproportionate, with greater interest in the soils of the larger forest biomes and less interest in the dry and flooded areas. The results of this study can be useful for the development of public policies, research and scientific collaboration aimed at soil conservation in Brazilian terrestrial biomes.

Purpose

Sediments are one of the ultimate destinies of polycyclic aromatic hydrocarbons (PAHs) in the environment. This study aims to investigate the distribution, source characteristics, and ecological risks of PAHs in black-odorous urban river sediments, providing support for environmental safety assessment and pollution control.

Material and methods

A total of 173 surface sediment samples were collected and analyzed for 17 types of PAHs using gas chromatography-mass spectrometry (GC-MS). The sources of PAHs were identified using isomer ratio indicator analysis and a positive matrix factorization model (PMF). Furthermore, the health risks of the PAHs were assessed using the Sediment Quality Guidelines and the organic carbon normalization method.

Results

The total PAH concentration ranged from 0.02 to 52 μg g⁻¹ dry weight. PMF and isomer ratio indicators revealed that the predominant sources were petroleum and fuel combustion. The ratio of perylene to pentacyclic aromatic isomers was < 10 in 75% of the samples. Most areas posed a low risk.

Conclusions

PAH concentrations exceeded those typically found in lakes and river surface sediments, ordinary industrial parks, and agricultural soils. However, no distinct spatial distribution was evident. The primary contributors were fossil, coal, and biomass fuel combustion. Moreover, the source of perylene exhibited spatial variability—natural biodiagenesis in South China and anthropogenic pyrolysis in North China. These suggest that as an index to trace the sediment footprint of large river influences, its environmental significance varied with different locations. The ecological risk assessment indicated that PAHs in most polluted urban river sediments posed low to moderate risks.

Purpose

Microbial necromass carbon (C) is a major contributor to soil organic C (SOC) sequestration. Soil aggregates are key functional units in regulating SOC dynamics. Fertilization and plastic film mulching, as common agricultural management practices, affect soil aggregation and microbial activities. However, how microbial necromass C is accumulated and contributes to organic C sequestration within soil aggregates remains poorly understood, especially under fertilization combined with plastic film mulching.

Methods

We set the mulching and no-mulching sub-treatments under three long-term (28 years) fertilization treatments (no fertilization, NF; inorganic fertilization, IF; manure application, MF) and conducted a 900-day field mesocosm experiment. We quantified the proportion of microbial necromass C in organic C within soil aggregates using amino sugar biomarkers, and investigated the effects of fertilization combined with mulching on the dynamics of microbial necromass C within soil aggregates.

Results

Microbial necromass C accounted for 28.2–42.9% of organic C of macroaggregates (> 0.25 mm) and 40.4–55.8% of organic C of microaggregates (< 0.25 mm) on day 900. The proportion of fungal necromass C in organic C of soil aggregates was nearly two times more than that of bacterial necromass C within 360–900 days. Regardless of mulching or no-mulching, the MF treatment increased the microbial necromass C content within macroaggregates and microaggregates, on average, by 148.6% and 84.5% compared with the NF treatment during the entire incubation period, respectively. Mulching facilitated microbial necromass C accrual within macroaggregates under the NF and IF treatments only on day 360, but increased it under the MF treatment on both day 360 and day 900. Mulching increased the fungal necromass C content and its contribution to organic C within macroaggregates by an average of 17.4% and 11.2% under the MF treatment during the entire incubation period, respectively.

Conclusions

Manure application combined with mulching promoted organic C sequestration within macroaggregates via the accumulation of fungal necromass C.

Purpose

Hypolimnetic hypoxia has become increasingly prevalent in stratified water bodies in recent decades due to climate change. One primary sink of dissolved oxygen (DO) is sediment oxygen uptake (({J}_{{O}_{2}})). On the water side of the sediment–water interface (SWI), ({J}_{{O}_{2}}) is controlled by a diffusive boundary layer (DBL), a millimeter-scale layer where molecular diffusion is the primary transport mechanism. In previous studies, the DBL was determined by visual inspection, which is subjective and time-consuming.

Material and methods

In this study, a computational procedure is proposed to determine the SWI and DBL objectively and automatically. The procedure was evaluated for more than 300 DO profiles in the sediment of three eutrophic water bodies spanning gradients of depth and surface area. Synthetic DO profiles were modeled based on sediment characteristics estimated by laboratory experiments. The procedure was further verified adopting the synthetic profiles.

Results and discussion

The procedure, which was evaluated for both measured and synthetic DO profiles, determined the SWI and DBL well for both steady and non-steady state DO profiles. A negative relationship between DBL thickness and aeration rates was observed, which agrees with existing literatures.

Conclusions

The procedure is recommended for future studies involving characterizing DBL to improve efficiency and consistency.