Soil & Environmental Health最新文献

Organic fertilizer-derived emerging contaminants, such as antimicrobials and estrogens, could migrate vertically into subsoil and potentially reach shallow groundwater aquifers. This study investigated the vertical distribution of these antimicrobials and estrogens in soil profiles, as well as their potential ecological risks, in the Yellow River Delta of China, a major agricultural zone. A total of 47 emerging contaminants, including 42 antimicrobials, 2 antimicrobial degradation products, and 3 estrogens, along with reference contaminant atrazine, were detected within 7 soil layers that were down to 1 ​m below the surface at 10 farmland sites. The concentrations of individual contaminants varied greatly in these soil layers, ranging from 0.0095 to 1680 ​ng/g. Antimicrobials were ubiquitous (detection frequency up to 85%), while estrogens were only detected occasionally (detection frequency up to 27%). The concentrations of antimicrobials and estrogens in subsoil were generally lower than those in topsoil, e.g., the total concentrations of antimicrobials and estrogens in Level 1 (0–5 ​cm) and Level 7 (70–100 ​cm) at all sampling sites were up to 99.3 and 29.2 ​ng/g, respectively. Nineteen out of the 26 emerging contaminants with relevant toxicity data could pose medium to high ecological risk to potential aquatic organisms, soil microbes, and/or crop plants. The ecological risks posed by the organic fertilizer-derived emerging contaminants were comparable in different soil layers in the soil profiles. These findings demonstrate the pseudo-persistence of these emerging contaminants in soil profiles and their substantial potential ecological risks. The data also indicate the need of controlling the residues of antimicrobials and estrogens in organic fertilizers to protect the quality and health of farmland soils.

Ionic liquids (ILs) are eco-friendly substitutes for volatile organic solvents due to their unique properties, fostering widespread adoption across academic fields and industries. This review critically evaluates their application in soil remediation, comparing their performance and environmental footprint against conventional soil remediating agents. The review provides insights into the interplay of IL characteristics, optimal environmental conditions, and contaminant removal mechanisms, while also exploring strategies for modifying and regenerating ILs. Optimal conditions for contaminant removal involve acidic pH for organic compounds and metals, with high temperatures proving beneficial for metal extraction. ILs remove organic contaminants from soil via electrostatic attraction and π–π interactions. In contrast, heavy metal extraction is facilitated by forming complexes through hydrogen bonding, coordination bonding, and electrostatic interactions. The incorporation of acetone and calcium chloride reduces the viscosity while sodium azide effectively prevents microbial degradation of ILs. Using magnetic ILs, acid elution, ultrasonication, and supercritical CO₂ extraction techniques enhances IL regeneration efficiency and facilitates their reuse, thereby minimizing secondary pollution and reducing cost. Life cycle assessment of common ILs for remediation, such as 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF₄]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF₆]) showed that producing 1 ​kg of [Bmim][BF₄] emits 6.75 ​kg CO₂, whereas manufacturing 1 ​kg of [Bmim][PF₆] releases 5.70 ​kg CO₂, indicating [Bmim][PF₆] has a lower global warming potential due to its environmentally-friendly precursors. The review advocates for continuous improvements in production processes and the development of ILs synthesized from renewable sources to mitigate environmental impacts and enhance their suitability for soil remediation.

Mine lands contaminted with heavy metals pose environmental risks, and thus reclamation is paramount for improving soil, plant, animal, and ecosystem health. A metal-contaminated alluvial mine tailing, devoid of vegetation, received 224 ​Mg ​ha⁻¹ of both lime and biosolids in 1998, and long-term reclamation success was quantified in 2019 with respect to soils, plants, and linkages to animals. Reclamation success was quantified using the Soil Management Assessment Framework (SMAF), in conjunction with bioavailable (0.01 ​M CaCl₂ extractable) and plant-available (Mehlich-3 extractable) soil metal concentrations, X-ray absorption spectroscopy, plant metal concentrations, and plant quality characteristics. Results showed that all soil indicators were improved in successfully-reclaimed areas as compared to on-site degraded areas, including increases in soil aggregate stability, pH, plant-available P and K, soil organic C, potentially-mineralizable N, microbial biomass C and β-glucosidase activity and decreases in soil bulk density and electrical conductivity. Ofindicators, unitless soil health scores were assigned based on the SMAF, with data suggesting that bulk density, wet aggregate stability, potentially- mineralizable N, microbial biomass C, pH, and electrical conductivity should be monitored in the future. The long-term effects of lime and biosolids application have improved soil physical, biological, and overall soil health. Plant metal concentrations have decreased by an order of magnitude since early reclamation, with most plant metal concentrations being tolerable for domestic livestock consumption. From an animal health perspective, feeding grasses from this site during latter parts of a growing season may need supplemental feed to provide greater protein and energy content, and to reduce potentially-harmful Cd concentrations from food chain bioaccumulation. However, a health concern exists based on soil bioavailable Cd and Zn concentrations that exceed ecological soil screening levels. Still, plants have stabilized the soil and acidity remains neutralized, leading to long-term improvements in soil health, with overall improved ecosystem health.

The rhizosphere hosts diverse microbes crucial for plant growth. This is because plant roots secrete organic compounds, thereby enriching the rhizosphere with essential nutrients. Biochar improves soil quality, while nano-biochar shows promise in contaminant adsorption. Its production from biochar is easily achievable through top-down methodologies including hydrothermal synthesis, ball-milling, sonication, and centrifugation. The advantages of employing nano-biochar are evident in several aspects. Nano-biochar exhibits enhanced properties such as greater surface area, increased porosity, and greater reactivity compared to bulk-biochar. This enhanced surface area allows for greater adsorption capacity, enabling nano-biochar to effectively immobilize contaminants in the environment. In this review, detailed interactions and applications of nano-biochar are summarized. Nano-biochar interacts with contaminants in the rhizosphere by electrostatic interaction, cation-π interactions and redox reactions, influencing soil microbial communities and plant resilience. Nano-biochar can adsorb contaminants from the rhizosphere, such as heavy metals and organic pollutants. Thus, it helps alleviate abiotic stresses, improves nutrient availability, and supports plant growth. Furthermore, the mechanistic processes of surface oxidation, mineral dissolution, organic matter release, and mechanical fragmentation in biochar are discussed, culminating in biochar ageing and nano-biochar formation, which creates a conducive environment for microorganisms. This review examines nano-biochar-rhizosphere interactions, highlighting their effects on plant-soil dynamics and resilience. Future research should address synthesis scalability and safety concerns to unlock nano-biochar's potential in sustainable agriculture and environmental management.

Environmental evaluations of metal nanoparticles (NP) rely on seperating the effects of the metal NP from its dissolution products. However, the coordinating or counter anion used in experimental controls may potentially influence biotic indicators used in ecotoxicology and soil health monitoring, thereby compromising the ability to detect real nanoparticle effects and potentially confounding interpretation of metal-NP impacts. Using the example of copper oxide (CuO) NP, we demonstrate for the first time that depending on the anion used in the metal ion control (CuCl₂ versus CuSO₄), different and even opposite conclusions may be drawn for CuO-NP effects. This include a key biological indicator such as enzyme activity in soil samples. Moreover, this effect was specific to environmental conditions and indicator type, raising important methodological and interpretive implications to assess the CuO-NP impacts on soils. Our findings imply that assessments of soil health impacts of metal-NP should consider multiple coordinating anion controls for a given metal, especially when the counterion is known to impact the biological indicator including nutrient ions.

The continuous use of fertilizers and fungicides has triggered copper (Cu) contamination in cacao soils in Ghana, which is a critical issue for the ecological risk and health safety of cacao products. In this study, we investigated Cu pollution, bioavailability, and ecological risk in soil and determined the Cu levels in the cacao nib, shell, and pod husk. Soils were collected at two soil depths (0–15 ​cm and 15–30 ​cm) from 20 cacao farms, under conventional (CCM: chemical-based fertilizers) and organic (OCM: organic-based fertilizers) management practices together with pods. The total Cu concentration ranged from 67.6 to 96.8 ​mg ​kg⁻¹ in OCM and 28.5–33.9 ​mg ​kg⁻¹ in CCM soil, which decreased with soil depth. The enrichment factor revealed minimal Cu enrichment, which was attributed to anthropogenic activity (fungicide and fertilizer applications). The contamination factor and geoaccumulation index values were low for the CCM soils, and moderate for the OCM soils. Both management systems pose a low potential ecological risk to soil biota activity. Bioavailable Cu extracted with CaCl₂, NH₄OAc, and DTPA was dominant in CCM soil and decreased with soil depth. The Cu concentration in cacao plants decreased in the order of shell > pod husk > nib, with nib-Cu being below the threshold (50.0 ​mg ​kg⁻¹) of contamination. The results from the pairwise correlation analysis show that CaCl₂-available Cu is better for evaluating the Cu content in cacao plants. This study reveals the pollution levels associated with cacao management practices, thus providing valuable insights for developing appropriate mitigation strategies.

Soil health is important, with soil chemical composition data, including potentially toxic elements (PTEs) being one of its conceptual components. This study aims to reveal the spatial distribution patterns of soil PTEs contents, identify their potential sources, and unveil their geochemical associations in Aragatsotn region, Armenia. For that purpose, the contents of Cr, V, Ti, As, Zn, Cu, Co, Fe, Mn, Ba, and Pb were determined using an X-ray fluorescence spectrometer. The mean contents of Cr and As exceeded their upper continental crust by 1.5 and 3.1 times and their maximum acceptable values by 1.5 and 1.5 times. The analysis demonstrated the presence of sites where all these elements displayed comparatively higher values. The combined application of compositional data analysis and geospatial mapping revealed multivariate outliers, which were located in structural-metallogenic zones with active ore exploitation . The application of unsupervised machine learning algorithm unveiled three groups within the main dataset and the clr-biplot identified the source-specific elements. Particularly, Group I included Cu and displayed the highest mean value among the identified groups. The soil samples included in Group I were in areas where Calcisols were developed and comparatively high Cu contents were attributed to agricultural activities and vehicle emissions. Group II is represented by the geochemical association of Fe, Co, Cr, Mn, Zn, and As. The formation of this group is conditioned by volcanic rocks of the local geological origin. However, no spatial pattern was identified in Group II distribution aligned with soil types. Group III included Ti, V, Pb, and Ba, which may have a mixed origin as it is spatially distributed in areas where regional highways pass through and where Group II elements also exhibit their higher values.

Efficient and sustainable sludge management is a significant environmental and health challenge. Sludge-treatment reed beds (STRBs) are widely recognized as a cost-effective, highly efficient, and environmentally friendly solution for sludge treatment and dewatering. This study investigated the bacterial community composition and diversity in pilot-scale STRBs operating at different sludge loading rates (75, 100, and 125 ​kg ​m² year⁻¹). 16S rRNA V4 DNA sequencing was used to assess the diversity of the bacterial communities within the sludge samples. The relative abundance of prokaryotic taxa was affected by all treatments. As the sludge loads increased, the Shannon entropy and evenness diversity also increased for the STRBs and unplanted beds. Interestingly, the presence of reeds resulted in significantly lower Shannon and evenness indices than unplanted beds, regardless of the sludge. Additionally, the correlation network analysis revealed distinct microbial clusters with distinct responses to reeds and sludge loads. Principal component analysis evidenced an association between cluster 5 and organic matter decomposition, primarily at higher sludge doses, while clusters 4 and 6 were related to sludge decomposition at lower doses. Additionally, cluster 4 was associated with nutrient removal. The formation of distinct microbial niches was linked to sludge stabilization and nutrient removal and was influenced by both sludge loading rates and the presence of reeds. Future research can leverage these findings to innovate pollutant removal and ecosystem services for sludge treatment, thus advancing sustainable sludge management and environmental preservation.

Extensive use of per- and polyfluoroalkyl substances (PFAS) in various industrial and consumer products in the past has led to their widespread distribution in the environment. PFAS contamination has become a major environmental and public health threat worldwide, especially in communities impacted by industrial, commercial, and military activities. In 2021, twelve soil samples were collected from three distinct site types in Brevard County, Florida, based on community concerns: background sites, primary-source sites, and secondary-source sites. These sites comprised samples collected from both residential and industrial/commercial areas. Ultra-high performance liquid chromatography-tandem mass spectrometry was used to identify and quantify PFAS in the samples. The results show that PFAS were present in all soil samples, with the lowest and the highest concentrations being in background and primary sites, respectively. Total PFAS concentrations in both primary and secondary sites were generally one-order of magnitude greater than those reported in background sites. Perfluorooctanesulfonic acid concentrations were the most predominant among the 34 species of PFAS detected in the samples, with concentrations ranging from 0.04 to 2.63 ​ng/g. Analysis of variance of PFAS data reveals significant difference among study sites, with greater diversity and concentrations near primary sources followed by secondary sites and background sites. The results also demonstrate that long-chained PFAS are significantly more abundant in these soils than short-chained PFAS. Overall, our results should help prioritize future sampling locations for a rapid and systematic identification of PFAS in soils.