Particulate matter (PM) is an air pollutant which poses a considerable risk to human health. The agricultural sector is responsible of the 15% of the total anthropogenic emissions of PM₁₀ (PM fraction with aerodynamic diameter below 10 μm) and soil preparation activities have been recognized as one of the main drivers of this contribution. The emission factors (EF) proposed by European environmental agency (EEA) for tilling operations are based on very few studies, none of which has been made in Italy. Moreover, few studies have considered the influence of operative parameters on PM₁₀ emissions during tilling. The aim of this work was to assess PM₁₀ emission and dispersion during rotary harrowing and to understand how operative parameters, such as forward speed and implement choice may affect PM release. A further objective was to assess the near field dispersion of PM₁₀ to address exposure risks. Emission factors (EFs) were determined during two different trials (T1 and T2). During T1, the effect of tractor speeds (0.6, 1.1 and 1.7 m s⁻¹) on PM₁₀ emissions was investigated, while in T2 a comparative essay was made to study the influence of levelling bar height on emissions. The average ground level downwind concentrations of PM₁₀ during harrowing operation was estimated through dispersion modelling. The observed PM₁₀ EFs for rotary harrowing were 8.9 ± 2.0 mg m⁻² and 9.5 ± 2.5 mg m⁻² on T1 and T2, respectively. The heavy metal content of soil-generated PM₁₀ was also assessed. In the generated PM, the elemental concentrations were higher than ones in soil. As, Cd and Ni concentration levels, determined in PM₁₀ near to the tractor path, were also high, being several times higher than the annual average regulatory threshold levels in ambient air, as defined by the European regulation.

Environmental pollution by pharmaceuticals such as diclofenac (DCF) is globally acknowledged to be a threat to the ecosystems. Nauphoeta cinerea is an important insect with valuable ecological role. The present investigation aimed to elucidate the impact of DCF on insects by assessing the behavior and antioxidant defense response in nymphs of N. cinerea exposed to DCF-contaminated food at 0, 0.5, 1.0 and 2.0 μg kg⁻¹ feed for 42 successive days. Subsequent to exposure period, neurobehavioral analysis using video-tracking software in a novel apparatus was performed before estimation of biochemical endpoints in the head, midgut and hemolymph of the insects. Results indicated that DCF-exposed insects exhibited marked reduction in the maximum speed, total distance traveled, mobile episodes, total mobile time, body rotation, absolute turn angle and path efficiency, whereas the total freezing time was increased compared with the control. The diminution in the exploratory activities of DCF-exposed insects was substantiated by heat maps and track plots. Additionally, DCF elicited marked diminution in antioxidant enzyme and acetylcholinesterase (AChE) activities along with increase in nitric oxide (NO), reactive oxygen and nitrogen species (RONS), and lipid peroxidation (LPO) levels in the head, midgut and hemolymph of the insects. Taken together, DCF elicited neurotoxicity and oxido-inflammatory stress in exposed insects. N. cinerea may be a suitable model insect for environmental risk assessment of pharmaceuticals in non-target insect species.

The conversion of natural forests to tea plantations largely affects soil nitrous oxide (N₂O) emissions and soil microbial communities. However, the impacts of this conversion on the contribution of fungi to N₂O emission and on fungal community structure remain unclear. In this study, we determined the soil N₂O emission rate, N₂O production by fungi, associated fungal community diversity, and related ecological factors in chronological changes of tea crop systems (3, 36 and 105 years old tea orchards named T3, T36 and T105, respectively), and in an adjacent soil from a natural forest. The results indicate that the tea plantations significantly enhanced soil N₂O production compared with the forest soil. Tea plantations significantly decreased soil pH and C/N ratio, but increased soil inorganic nitrogen (N). Furthermore, they increased the fungal contribution to the production of soil N₂O, but decreased the bacterial counterpart. We also observed that fungal community and functional composition differed distinctly between tea plantations and forest. Additionally, most of the fungal groups in high N₂O emission soils (T36 and T105) were identified as the genus Fusarium, which were positively correlated with soil N₂O emissions. The variation in N₂O emission response could be well explained by NO₃⁻-N, soil organic carbon (SOC), C/N, and Fusarium, which contributed to up to 97% of the observed variance. Altogether, these findings provide significant direct evidence that the increase of soil N₂O emissions and fungal communities be attributed to the conversion of natural forest to tea plantations.

This study investigated the relationship between lead (Pb) speciation determined using Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy in <10 μm particulate matter (PM₁₀) from mining/smelting impacted Australian soils (PP, BHK5, BHK6, BHK10 and BHK11) and inhalation exposure using two simulated lung fluids [Hatch’s solution, pH 7.4 and artificial lysosomal fluid (ALF), pH 4.5]. Additionally, elemental composition of Pb rich regions in PP PM₁₀ and the post-bioaccessibility assay residuals were assessed using a combination of Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDX) to provide insights into how extraction using simulated lung fluids may influence Pb speciation in vitro. Correlation between Pb speciation (weighted %) and bioaccessibility (%) was assessed using Pearson r (α = 0.1 and 0.05). Lead concentration in PM₁₀ samples ranged from 782 mg/kg (BHK6) to 7796 mg/kg (PP). Results of EXAFS analysis revealed that PP PM₁₀ was dominated by Pb adsorbed onto clay/oxide, while the four BHK PM₁₀ samples showed variability in the weighted % of Pb adsorbed onto clay/oxide and organic matter bound Pb, Pb phosphate, anglesite and galena. When bioaccessibility was assessed using different in vitro inhalation assays, results varied between samples and between assays, Pb bioaccessibility in Hatch’s solution ranged from 24.4 to 48.4%, while in ALF, values were significantly higher (72.9–96.3%; p < 0.05). When using Hatch’s solution, bioaccessibility outcomes positively correlated to anglesite (r:0.6246, p:0.0361) and negatively correlated to Pb phosphate (r: -0.9610, p:0.0041), organic bound Pb (r: -0.7079, p: 0.0578), Pb phosphate + galena + plumbojarosite (r: -0.9350, p: 0.0099). No correlation was observed between Pb bioaccessibility (%) using Hatch’s solution and weighted % of Pb adsorbed onto clay/oxide and between bioaccessibility (%) using ALF and any Pb species. SEM and EDX analysis revealed that a layer of O–Pb–Ca–P–Si–Al–Fe formed during the in vitro extraction using Hatch’s solution.

Spread of antibiotic resistance genes (ARGs) poses a worldwide threat to public health and food safety. However, ARG spread by plasmid mobilization, a broad host range transfer system, in agricultural soil has received little attention. Here, we investigated the spread of chloramphenicol resistance gene (CRG) and tetracycline resistance gene (TRG) in agricultural soil by mobilization of pSUP106 under different conditions, including different concentrations of nutrients, temperatures, soil depths, rhizosphere soils, and soil types. The number of resistant bacteria isolated in non-sterilized soil from the experiments was approximately 10⁴ to 10⁷ per gram of soil, belonging to 5–10 species from four genera, including nonpathogen, opportunistic pathogen, pathogen bacteria, and gram-positive and gram-negative bacteria, depending on the experiment conditions. In sterilized soil, higher levels of nutrients and higher temperatures promoted plasmid mobilization and ARG expression. Topsoil and deep soil might not support the spread of antibiotic resistance, while ARG dissemination by plasmid mobilization was better supported by maize rhizosphere and loam soils. All these factors might change bacterial growth and the activity of bacteria and lead to the above influence. Introduction of only the donor and helper, or the donor alone also resulted in the transfer of ARGs and large numbers of antibiotic resistant bacteria (ARB), indicating that some indigenous bacteria contain the elements necessary for plasmid mobilization. Our results showed that plasmid mobilization facilitated dissemination of ARGs and ARB in soil, which led to the disturbance of indigenous bacterial communities. It is important to clear ARG dissemination routes and inhibit the spread of ARGs.

The microbial characteristics and bacterial communities of sediment sludge upon different concentrations of exposure to uranium were investigated by high solution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and high-throughput sequencing. After exposure to initial uranium concentrations of 10–50 μM for 24 h in synthetic wastewater, the removal efficiencies of uranium reached 80.7%–96.5%. The spherical and short rod bacteria were dominant in the sludge exposed to uranium. HRTEM-EDS and XPS analyses indicated that reduction and adsorption were the main mechanisms for uranium removal. Short-term exposure to low concentrations of uranium resulted in a decrease in bacterial richness but an increase in diversity. A dramatic change in the composition and abundances of the bacterial community were present in the sediment sludge exposed to uranium. The highest removal efficiency was identified in the sediment sludge exposed to 30 μM uranium, and the dominant bacteria included Acinetobacter (44.9%), Klebsiella (20.0%), Proteiniclasticum (6.7%), Enterobacteriaceae (6.6%), Desulfovibrio (4.4%), Porphyromonadaceae (4.1%), Comamonas (2.4%) and Sedimentibacter (2.3%). By comparison to the inoculum sediment sludge, exposure to uranium caused a substantial difference in the majority of bacterial abundance.

Long-term trends (2004–2017) in the chemical composition and sources of PM₂.₅ (particulate matter smaller than 2.5 μm in diameter) in a metropolitan area were investigated using daily integrated PM₂.₅ chemical speciation data and continuous air pollution measurements. Eleven source factors were identified: coal combustion characterized by secondary sulphate, secondary nitrate, summertime organic carbon (OC), regional elemental carbon (EC), biomass burning, oil combustion, primary tailpipe emissions, non-tailpipe emissions related to road dust, non-tailpipe emissions related to brake wear, metal production, and road salt. Overall, coal combustion, secondary nitrate, regional EC, and oil combustion underwent marked decreases in concentrations with large reduction rates ranging from −8% yr⁻¹ to −18% yr⁻¹, contributing to an overall 34% decrease in annual PM₂.₅ over the past 14 years. Decreases in local tailpipe emissions (−3% yr⁻¹) were consistent with the reduction of traffic-related air pollutants. In contrast, non-tailpipe emissions remained constant until 2010–2011 and then increased with a range of rates of 21% yr⁻¹ to 27% yr⁻¹ from 2011 to 2016. The contribution of summertime OC increased to approximately 27% in the summer of 2013–2016, rising to become the largest PM₂.₅ source driven by the reduction of regional sources. The chemical composition of PM₂.₅ in the urban area drastically changed from inorganic-rich to organic- and metal-rich particles during 2013–2016. The depletion of ascorbic acid was measured using filter samples collected over one year to identify PM₂.₅ components and sources contributing to the oxidative potential (OP) of PM₂.₅. The OP was clearly associated with trace elements (e.g., Ba, Cu, Fe). Non-tailpipe emissions related to road dust and brake wear presented high redox activity per mass of PM₂.₅. This work suggests that summertime OC and non-tailpipe emissions in recent years have become increasingly important. As such, policies targeting traffic-related PM₂.₅ should focus on these sources for maximum impact.

Ground-level ozone (O₃) pollution and its impact on crop growth and yield have become one of the serious environmental problems in recent years, especially in economically active and densely populated areas. In this study, rice yield and the associated economic losses due to O₃ were estimated by using observational O₃ concentration ([O₃]) data during growing seasons in Southern China. O₃-induced yield losses were calculated by using O₃ exposure metrics of AOT40 and M7. The spatial distribution of these two metrics is relatively consistent, the highest areas located in the Yangtze River Basin. Under the current O₃ level, during double-early rice, double-late rice and single rice growing seasons, the relative yield losses estimated with AOT40 (M7) were 6.8% (1.2%), 10.2% (1.9%) and 10.4% (2.0%), respectively. O₃-induced rice production loss for double-early rice, double-late rice and single rice totaled 2.4 million metric tons (0.4 million metric tons), 4.3 million metric tons (0.7 million metric tons) and 11.0 million metric tons (1.9 million metric tons) and associated economic losses were 108.1 million USD (18.3 million USD), 190.2 million USD (32.4 million USD) and 486.4 million USD (82.9 million USD) based on AOT40 (M7) metric. This study indicates that regional risks to rice from O₃ exposure and provide quantitative evidence of O₃-induced impacts on rice yields and economic losses across Southern China. Therefore, the establishment of scientific O₃ risk assessment method is of great significance to prevent yield production and economic losses caused by O₃ exposure. Policymakers should strengthen supervision of emissions of O₃ precursors to mitigate the rise of O₃ concentration, thereby reducing O₃ damage to agricultural production.

Fulvic acid (FA) significantly influences the bioavailability and fate of heavy metals in environments, while its acid-base characters and metal binding processes are still unclear. Here, spectroscopic techniques combined with multiple models (e.g., NICA-Donnan model) and two-dimensional correlation spectroscopy (2D COS) were applied to explore the proton and copper binding properties of FA sub-fractions (FA3-FA13). The charge densities, average contents of carboxylic and phenolic groups, average dissociation constants pKa1 and pKa2 of sub-fractions ranged 0–16 meq∙g∙C−1, 5.03–9.58 meq∙g∙C−1, 2.52–4.67 meq∙g∙C−1, 4.15–4.33 and 8.52–9.72, respectively. FA sub-fractions had a relatively narrow distribution of carboxyl group and a broad distribution of phenolic group. FA sub-fractions also exhibited roughly two phenolic hydroxyl groups per every 1–3 phenyl rings. Differential absorbance spectra (DAS) derived Gaussian bands were associated to the inter-chromophore interactions, the changes of molecular conformations and functional groups with copper addition. Differential spectra slopes (DSlope275-295&325-375) were more significant with higher copper concentration and copper amounts bonded to carboxylic groups. UV–Vis and fluorescence spectra with 2D heterospectral COS revealed the copper binding heterogeneities and sequential orders of chromophores and fluorophores, quantitatively confirming by the order of conditional stability constants (log KCu: 4.64–5.56). Salicylic-/polyhydroxyphenolic, hydroxyl and amino groups were strongly associated to the basic units for fluorophores. Sequential changes followed the order of humic-like→fulvic-like materials for FA3/FA5, humic-like→fulvic-like→tryptophan-like materials for FA7, and humic-like→tryptophan-like→fulvic-like→tyrosine-like materials for FA9/FA13. Spectroscopic techniques combined with various models (especially for 2D COS) are beneficial to elucidate the binding heterogeneity and sensitivity for metal-organic matters at the functional group level.

Rivers can receive the input of treated or untreated sewage effluents from wastewater treatment plants, urban and industrial discharges and agricultural run-off, becoming an important pathway for the transport and mobilization of pollutants to the oceans. In the present study, the occurrence of 20 PFAAs was determined in the water of Tagus River basin (Spain). PFAAs were detected in 76 out of 92 water samples collected during 5 years (2013–2018), being perfluorooctanesulfonic acid (PFOS) the predominant compound (<0.01–34 ng/L). The annual average PFOS concentrations (2.9–11 ng/L) detected in Tagus River were above the annual average environmental quality standards (AA-EQS) established in the Directive, 2013/39/EU (0.65 ng/L for inland surface waters) but below the maximum allowable concentration (MAC-EQS; 36000 ng/L). The levels of PFAAs detected in urban and industrial areas were statistically higher (p < 0.01) than those at background or remote areas. The mass flow rates amounted to <0.01–46 kg/y for PFOS and <0.01–22 kg/y for perfluorooctanoic acid (PFOA). A quantitative ecotoxicological risk assessment was conducted to evaluate the environmental potential risk related to PFAAs in the aquatic ecosystem. Risk characterization ratios (RCRwater, RCRsed and RCRoral, fish) were below 1 in all cases.