The presence of manufactured nano-objects (MNOs) in various consumer or their (future large-scale) use as nanoagrochemical have increased with the rapid development of nanotechnology and therefore, concerns associated with its possible ecotoxicological effects are also arising. MNOs are releasing along the product life cycle, consequently accumulating in soils and other environmental matrices, and potentially leading to adverse effects on soil biota and their associated processes. Earthworms, of the group of Oligochaetes, are an ecologically significant group of organisms and play an important role in soil remediation, as well as acting as a potential vector for trophic transfer of MNOs through the food chain. This review presents a comprehensive and critical overview of toxic effects of MNOs on earthworms in soil system. We reviewed pathways of MNOs in agriculture soil environment with its expected production, release, and bioaccumulation. Furthermore, we thoroughly examined scientific literature from last ten years and critically evaluated the potential ecotoxicity of 16 different metal oxide or carbon-based MNO types. Various adverse effects on the different earthworm life stages have been reported, including reduction in growth rate, changes in biochemical and molecular markers, reproduction and survival rate. Importantly, this literature review reveals the scarcity of long-term toxicological data needed to actually characterize MNOs risks, as well as an understanding of mechanisms causing toxicity to earthworm species. This review sheds light on this knowledge gap as investigating bio-nano interplay in soil environment improves our major understanding for safer applications of MNOs in the agriculture environment.

Engine oil-derived ash particles emitted from internal combustion (IC) engines are unwanted by-products, after oil is involved in in-cylinder combustion process. Since they typically come out together with particulate emissions, no detail has been reported about their early-stage particles other than agglomerated particles loaded on aftertreatment catalysts and filters. To better understand ash formation process during the combustion process, differently formulated engine oils were dosed into a fuel system of a gasoline direct injection (GDI) engine that produces low soot mass emissions at normal operating conditions to increase the chances to find stand-alone ash particles separated from soot aggregates in the sub-20-nm size range. In addition to them, ash/soot aggregates in the larger size range were examined using scanning transmission electron microscopy (STEM)-X-ray electron dispersive spectroscopy (XEDS) to present elemental information at different sizes of particles from various oil formulations. The STEM-XEDS results showed that regardless of formulated oil type and particle size, Ca, P and C were always contained, while Zn was occasionally found on relatively large particles, suggesting that these elements get together from an early stage of particle formation. The S, Ca and P K-edge X-ray absorption near edge structure (XANES) analyses were performed for bulk soot containing raw ash. The linear combination approach & cross-checking among XANES results proposed that Ca₅(OH)(PO₄)₂, Ca₃(PO₄)₂ and Zn₃(PO₄)₂ are potentially major chemical compounds in raw ash particles, when combined with the STEM-XEDS results. Despite many reports that CaSO₄ is a major ash chemical when ash found in DPF/GFP systems was examined, it was observed to be rarely present in raw ashes using the S K-edge XANES analysis, suggesting ash transformation.

Pesticides may alter soil microbial community structure or diversity, but their impact on microbial co-occurrence patterns remains unclear. Here, the effect of the widely used neonicotinoid insecticide thiamethoxam on the bacterial community in five arable soils was deciphered using the 16S rRNA gene amplicon sequencing technique. The degradation half-life of thiamethoxam in nonsterilized soils was significantly lower than that in sterilized soils, suggesting a considerable contribution from biodegradation. Soil bacterial community diversity diminished in high concentration thiamethoxam treatment and its impact varied with treatment concentration and soil type. Bacterial co-occurrence network complexity significantly decreased after exposure to thiamethoxam. Under thiamethoxam stress, the relative changes in bacterial co-occurrence networks were closely related (the majority of p-values < 0.05) to the soil physicochemical properties, yet the diversity and dominant phyla were slightly related (the majority of p-values > 0.05). Additionally, three bacterial genera, Sphingomonas, Streptomyces, and Catenulispora, were identified to be relevant to the degradation of thiamethoxam in soils. This finding deciphers the succession of the bacterial community under thiamethoxam stress across multiple soils, and emphasizes the potential role of physicochemical properties in regulating the ecotoxicological effect of pesticides on the soil microbiome.

Emerging evidence has demonstrated that exposure to fine particulate matter (PM₂.₅) is a risk factor for lipid metabolic disorders in the liver. However, the effects of PM₂.₅ exposure time duration on hepatic lipid metabolism remain unknown. In this study, C57BL/6 mice were randomly divided into ambient PM₂.₅ (PM) or filtered air (FA) exposure chamber for short-term (4 weeks) or long-term (24 weeks) exposure via a whole body exposure system. We measured hepatic triglyceride and free fatty acid levels and analyzed the alteration of lipometabolism-related molecules in the liver. We found that triglyceride levels were significantly elevated in both short-term and long-term PM₂.₅-exposed mice and free fatty acid levels were increased after long-term PM₂.₅ exposure. Besides, enzymes for lipolysis and fatty acid oxidation in the liver were inhibited after short-term PM₂.₅ exposure but adaptively enhanced after long-term PM₂.₅ exposure. Furthermore, molecules for fatty acid uptake were down-regulated in the short-term PM₂.₅-exposed mice whereas molecules for lipid export were induced after long-term PM₂.₅ exposure. Therefore, ambient PM₂.₅ exposure disturbed hepatic lipid metabolism and the effects varied in different exposure duration. These findings in mice provide new insight into the biological basis of PM₂.₅-induced human metabolic dysfunction and specific strategies may be applied based on different exposure time periods.

Condensable particulate matter (CPM) is quickly formed by several gaseous substances in flue gas after emission and belongs to primary particulate matter emitted into the atmosphere by stationary sources. Many studies have shown that current CPM emissions from coal-fired stationary sources far exceed filterable particulate matter, and the issue of CPM emissions has attracted widespread attention. The current research on CPM mainly focuses on its emission characteristics in stationary sources and its migration characteristics in pollutant-controlled equipment, lacking the characteristics of CPM directly generated by fuel combustion. In this study, a one-dimensional flame furnace is used as a stable source of flue gas in the laboratory. The concentration (including inorganic and organic components) and chemical composition (including water-soluble ions, metal elements, and organic matters) of CPM are obtained by the combustion of three kinds of coal (Inner Mongolia lignite, Jinjie bitumite, and Ningxia anthracite) that China consumes in large amounts. The characteristics of CPM including emission factors obtained from different kinds of coal under various experimental conditions are comparatively analyzed. Moreover, a scanning electron microscope–energy-dispersive spectrometer is used to observe the morphology and elemental composition of CPM collected on the filter membrane after the combustion of different kinds of coal. Results show that CPM is mainly in the form of droplets or spheres, and heavy metal elements such as Hg, As, Se, and Sb are detected. These valuable data will enrich people’s understanding of the characteristics of CPM generated by coal combustion and can provide data references for evaluating the influence of CPM on the environment.

Strobilurin fungicides have been frequently detected in aquatic environments and can induce mitochondrial toxicity to non-target aquatic organisms. However, the derived toxicity and subsequent mechanisms related to their adverse effects are not fully elucidated. In the present study, we compared the mitochondrial and developmental toxicity of azoxystrobin, pyraclostrobin, and trifloxystrobin using zebrafish embryo/larvae. The results showed that all three strobilurins inhibited mitochondrial and non-mitochondrial respiration (the potency is pyraclostrobin ≈ trifloxystrobin > azoxystrobin). Behavioral changes indicated that sublethal doses of pyraclostrobin and azoxystrobin caused hyperactivity of zebrafish larvae in dark cycles, whereas trifloxystrobin resulted in hypoactivity of zebrafish larvae. In addition, pyraclostrobin exposure impaired the inflation of swim bladder, and caused down-regulation of annexin A5 (anxa5) mRNA levels, and up-regulated transcript levels of pre-B-cell leukemia homeobox 1a (pbx1a); conversely, azoxystrobin and trifloxystrobin did not cause detectable effects with swim bladder inflation. Molecular docking results indicated that azoxystrobin had higher interacting potency with iodotyrosine deiodinase (IYD), prolactin receptor (PRLR), antagonistic conformation of thyroid hormone receptor β (TRβ) and glucocorticoid receptor (GR) compared to pyraclostrobin and trifloxystrobin; pyraclostrobin and azoxystrobin were more likely to interact with the antagonistic conformation of TRβ and GR, respectively. These results may partially explain the different effects observed in behavior and swim bladder inflation, and also point to potential endocrine disruption induced by these strobilurins. Taken together, our study revealed that all three strobilurins alter mitochondrial bioenergetics and cause developmental toxicity. However, the toxic phenotypes and underlying mechanisms of each chemical may differ, and this requires further investigation. Pyraclostrobin showed higher mitochondrial toxicity at lethal doses and higher developmental toxicity at sublethal doses compared to the two other strobilurins tested. These results provide novel information for toxicological study as well as risk assessment of strobilurin fungicides.

Herbicide application is a practice commonly used in agricultural systems because it is an efficient method of weed control. An inherent characteristic of some herbicides used in mountain agriculture, such as oxyfluorfen, is high adsorption to soil organic matter (SOM). Thus, intensive management that changes the quantity and quality of SOM, such as soil tillage and the massive application of organic fertilizers such as poultry litter, may favor soil contamination by this herbicide and alter its dynamics in the environment. Therefore, this study aimed to characterize the structures of humic substances (HSs) in the soil of forest areas and areas with intensive production of vegetables, relating them to the accumulation of the herbicide oxyfluorfen in tropical mountain agroecosystems. Organic carbon content was quantified in HSs, humic acid (HAs) were structurally characterized by CP/MAS ¹³C-NMR spectroscopy, and the oxyfluorfen molecule was detected and quantified using the QuEChERS residue detection method with subsequent analysis by LC-MS/MS. Oxyfluorfen was not detected in the forest areas, but it was detected in the vegetable growing areas at points with the lowest slope and high contents of organic matter and clay, with values of up to 0.13 mg kg⁻¹. The intensification in the SOM mineralization process, promoted by the intensive management adopted in the vegetable growing areas, resulted in a 16.46% reduction in COT, a 58.84% reduction in the carbon content in the form of SH and a reduction in the structures that give recalcitrance to the HA molecule (CAₗₖyₗ-H,R, CCOO–H,R, CAᵣₒₘₐₜᵢc-H,R, and CAᵣₒₘₐₜᵢc-O) when compared to those values in the forest area, presenting HAs with more aliphatic and labile properties. Thus, due to the structural characteristics of the HAs in the vegetable production areas, the herbicide oxyfluorfen showed a close relationship with the more aliphatic oxygenated structures, namely, CAₗₖyₗ-O,N, CAₗₖyₗ-O and CAₗₖyₗ-di-O.

Rare earth elements have been increasingly used in modern societies and soils are likely to be the final destination of several REE-containing (by)products. This study reports REE contents for topsoils (0–20 cm) of 175 locations in reference (n = 68) and cultivated (n = 107) areas in Brazil. Benchmark soil samples were selected accomplishing a variety of environmental conditions, aiming to: i) establishing natural background and anthropogenic concentrations for REE in soils; ii) assessing potential contamination of soils - via application of phosphate fertilizers - with REE; and, iii) predicting soil-REE contents using biomes, soil type, parent material, land use, sand content, and biomes-land use interaction as forecaster variables through generalized least squares multiple regression. Our hypotheses were that the variability of soil-REE contents is influenced by parent material, pedogenic processes, land use, and biomes, as well as that cultivated soils may have been potentially contaminated with REE via input of phosphate fertilizers. The semi-total concentrations of REE were assessed by inductively coupled plasma mass spectrometry (ICP-MS) succeeding a microwave-assisted aqua regia digestion. Analytical procedures followed a rigorous QA/QC protocol. Soil physicochemical composition and total oxides were also determined. Natural background and anthropogenic concentrations for REE were established statistically from the dataset by the median plus two median absolute deviations method. Contamination aspects were assessed by REE-normalized patterns, REE fractionation indices, and Ce and Eu anomalies ratios, as well as enrichment factors. The results indicate that differences in the amounts of REE in cultivated soils can be attributed to land use and agricultural sources (e.g., phosphate-fertilizer inputs), while those in reference soils can be attributed to parent materials, biomes, and pedogenic processes. The biomes, land use, and sand content helped to predict concentrations of light REE in Brazilian soils, with parent material being also of special relevance to predict heavy REE contents in particular.

Neonicotinoid insecticides (NIIs) are extensively used worldwide and frequently detected in the environment. The human and ecological risks associated with the occurrence of NIIs in agricultural zones are of high importance. The present study highlights the regional occurrence and human exposure risks of NIIs in agricultural soil within the Pearl River Delta (PRD), South China. Six neonicotinoids, i.e., imidacloprid, clothianidin, acetamiprid, imidaclothiz, dinotefuran, and flonicamid, were measured in 351 soil samples from Zengcheng, a typical agricultural zone. The soil samples were categorized into three groups based on cultivated plants: vegetables, rice, and fruits. At least one of these neonicotinoid insecticides was detected in 95% of the soil samples. The levels of ∑₆NII (range (median)) were 0.26–390 (23), 0.26–280 (6.1), and 0.26–120 (5.0) ng g⁻¹ dry weight in soil samples from vegetable farms, rice paddies, and fruit farms, respectively. Neonicotinoids were detected more frequently and at statistically higher concentrations in vegetable farms than in both rice paddies and fruit farms. This is likely ascribed to higher application frequencies of NIIs in vegetable farms due to higher planting frequencies. The hazard index values for human exposure to NIIs in the agricultural soils were all below 1, suggesting negligible non-cancer risks. The current residual levels of NIIs in the soils could however pose sub-lethal or acute effects to non-target terrestrial organisms such as earthworms. The present study suggests that more information is needed regarding NIIs contamination in soils from agricultural regions of South China to ensure that human and ecological risk from exposure to these compounds can be fully addressed.

First flush or the first pore volume of effluent eluted from biofilters at the start of rainfall contributes to most pollution downstream because it typically contains a high concentration of bacterial pathogens. Thus, it is critical to evaluate designs that could minimize the release of bacteria during a period of high risk. In this study, we test the hypothesis of whether an addition of iron-based media to biofilter could limit the leaching of Escherichia coli (E. coli), a pathogen indicator, during the first flush. We applied E. coli-contaminated stormwater intermittently in columns packed with a mixture of sand and compost (70:30 by volume, respectively) and iron filings at three concentrations: 0% (control), 3%, and 10% by weight. Columns packed with a mixture of sand and iron (3% or 10%) without compost were used to examine the maximum capacity of iron to remove E. coli. In columns with iron, particularly 10% by weight, the leaching of E. coli during the first flush was 32% lower than the leaching from compost columns, indicating that the addition of iron amendments could decrease first-flush leaching of E. coli. We attribute this result to the ability of iron to increase adsorption and decrease growth during antecedent drying periods. Although the addition of iron filings increased E. coli removal, the presence of compost decreased the adsorption capacity: exposure of 1 g of iron filings to 1 mg of DOC reduces E. coli removal by 8%. The result was attributed to the alteration of the surface charge of iron and blocking of adsorption sites shared by E. coli and DOC. Collectively, these results indicate that the addition of sufficient amounts of iron media could decrease pathogen leaching in the first flush effluent and increase the overall biofilter performance and protect downstream water quality.