Journal of Soils and Sediments最新文献

Purpose: Riverbed sediment geochemistry provides useful information regarding metal contamination. To integrate sediment quality in river monitoring, within the WFD, the report of sediment quality to water quality managers must be expeditious. This study revisits the metal enrichment concept, applied to sediments from two mountain catchments, as a useful technique in river monitoring.

Methods: Riverbed sediment samples, collected at the end of the Dry and Wet Periods (DP, WP) were analysed for Cd, Cu, Pb, Zn, and Fe in fractions < 2 mm and < 63 µm. The metal enrichment factors (EFs) were referenced to distinct background values: average shale (AS), world rivers suspended sediments (WRSS) and Geochemical Atlas of Portugal (GAP).

Results: Cd, Cu, Pb and Zn contents are higher in the fraction < 63 µm, and at DP. The ranges of variation in fraction < 63 µm are (mg kg^-1): a) River Vilariça, Cd (5-18 DP; 0.3 WP); Cu (103-341 DP; 22-218 WP); Pb -(24-55 DP; 11-42 WP); Zn (107-241 DP; 54-103 WP); b) River Vizela, -Cd (13-44 DP; 8-41 WP); Cu (267-444 DP; 18-168 WP); Pb -(44-132 DP; 20-42 WP); Zn (141-801 DP; 36-181 WP). Variations in metal contents are influenced by lithological, geomorphological, and microclimatic features, and anthropogenic pressures. EFs are higher when referenced to AS. In the River Vizela, the EFs reveal an enrichment of Cu, Pb and Zn relative to WRSS; Cd registers an enrichment relative to GAP.

Conclusion: Local/regional background, and EFs, are relevant when assessing environmental risks in freshwater systems: low EFs, when associated to natural enrichments, originate values of concern in terms of quality guidelines; high EFs may not imply risk to the fluvial environment. Using the fraction < 63 µm in river monitoring is considered adequate. In dynamic mountain streams, recent sediments and associated contaminants are retained, providing information on possible pollution sources. Identifying metals contamination (or natural enrichment) can help decision-makers to provide solutions for pollution sources.

Supplementary information: The online version contains supplementary material available at 10.1007/s11368-025-03963-6.

Purpose: Insight into the distribution and sedimentation patterns of organic and inorganic carbon (OC and IC) in urban lake sediments is essential for understanding their role in the carbon (C) cycling of inland waters and supporting effective ecosystem management.

Methods: This study investigated the spatial variability of sediment OC and IC accumulation in a mesotrophic human-made urban lake (Lake Berendonck; 45 ha) by combining high-resolution hydroacoustic sub-bottom profiling surveys and sediment coring.

Results: The results revealed strong spatial variations in sediment C accumulation rates. Deep central and southeastern areas of the lake exhibited relatively high C deposition, even though deep areas with low C content were also found. Lake Berendonck had a mean ± standard deviation sediment accumulation rate of 0.7 ± 0.5 cm year^- 1, with areal OC and IC accumulation rates ranging between 24 and 557 and 3-37 g m^- 2 year^- 1, respectively. Lake Berendonck's mean sediment OC accumulation rate (155 g m^- 2 year^- 1) was approximately four times higher than the mean OC accumulation rate of global lakes (37 g m^- 2 year^- 1), while Lake Berendonck's mean IC accumulation rate (12 g m^- 2 year^- 1) falls in the mid-range for global lakes and seas.

Conclusions: Our findings indicate that C accumulation is highly variable in space and that spatially integrated data are needed to estimate C stocks and unravel within-lake C processes reliably. Furthermore, this study highlights that the OC accumulation in Lake Berendonck ranks among the highest rates observed in global lakes with similar surface areas (0.4-0.5 km²). This underscores the global importance of small urban water bodies in C cycling, particularly as key C storage systems.

Supplementary information: The online version contains supplementary material available at 10.1007/s11368-025-04029-3.

Purpose: Large soil organic carbon (SOC) reserves and a high soil capacity for SOC storage within an ecosystem contribute to mitigating the release of carbon into the atmosphere. Developing new spatially-explicit SOC estimation methods at local and micro-watershed scales is essential for gaining landscape understanding of SOC variability.

Methods: This study provides new insights into the spatial variability of SOC in the Andean páramo soils. A range of variables from different sources (i.e., geophysical, meteorological, topographic, and spectral) were analyzed to identify driving variables to explain the SOC dynamic in the Andean páramo highlands of the Real range in the central region of Ecuador. This information was used to calibrate a SOC prediction model using Classification and Regression Trees (CART) and soil data samples from the 0-30 cm soil horizon.

Results: Eight key variables linking with the SOC storage were used to calibrate the model for SOC estimation with an accuracy of 67% with an RMSE value of 2.17%. Results reveal that sand content emerged as the most significant variable, while taxonomic suborder and protected area variables provided crucial supplementary information. This study improves the ability to detect changes in SOC, particularly in smaller areas where traditional predictors, often more suitable for regional or national assessments, may exhibit insufficient explanatory power.

Conclusion: The Andean páramo highlands of the Real range show high capacity for storing SOC, with values ranging from 3.5% to 19%. This variability highlights the ecosystem's importance as a globally relevant carbon reservoir.

Purpose

This study aims to evaluate the impact of peanut straw mulching on the N change and the functional genes in Camellia oleifera intercropping systems.

Methods

A field experiment with different types of straw mulch treatments (conventional tillage, whole, and crushed) and timing was (50 d and 150 d) established between 2018–2022; the soil N fractions, N transformation rates, the abundance and dominant species compositions of ammonia-oxidizing archaea (AOA), nirK, and nirS-harboring genes were investigated.

Results

The whole peanut straw mulching of 150 d significantly improved (P < 0.05) the content of soil microbial biomass N (MBN), ammonia N (NH₄⁺), and nitrate N (NO₃^-). The soil nitrification and ammonification rates increased by 96.8% and 132% in the 150 d of peanut crushed and whole straw mulching, respectively. Notably, the peanut straw mulching of 50 d mainly affects the diversity and relative abundance of AOA while the soil nirK and nirS-harboring genes were affected by 150 d crushed and whole peanut straw mulching, respectively. Redundancy analysis showed that crushed and whole peanut straw mulching affects nitrate reductase as the primary factor in regulating the soil N cycle via functional genes and soil variables.

Conclusions

Long-term whole peanut straw or whole and crushed mixed straw mulching could hence be recommended to dryland farming communities to increase the soil N cycle and crop productivity in the C.oleifera-peanut intercropping system.

Purpose

Chemical immobilization using hydroxyapatite (HAP) is a cost effective and environmentally sound strategy for remediating lead-contaminated soils, such as shooting range soils. Understanding the combined impact of soil chemical and physical properties on enhancing the formation of pyromorphite, a lead-insoluble phase, is crucial for mitigating environmental risks associate with contaminated soil. This study aimed to elucidate the relationship between percolation velocity and lead leaching as well as pyromorphite transformation to optimize pyromorphite formation in water-unsaturated soils.

Methods

Two up-flow suction percolation tests were performed: one varying percolation velocity with soil porosity achieved by incorporating clay minerals, and the other varying percolation velocity while keeping soil porosity constant.

Results

Application of HAP substantially suppressed lead leaching in both percolation tests. Enhanced pyromorphite formation was observed with higher percolation velocities relative to soil porosity. Pyromorphite formation was more pronounced at lower percolation velocities compared to higher velocities at equivalent soil porosity level. The percentages of lead formed as pyromorphite in HAP-treated soil were higher than those of lead leached in non-HAP-treated soil among the lower percolation velocities.

Conclusions

This study provides experimental evidence indicating pyromorphite formation is favored in soils with lower percolation velocities and higher soil porosities. Therefore, considering both soil chemical and physical properties is essential for understanding immobilization mechanisms in contaminated soils.