While applying animal manure remain widespread agricultural practices for resources recycling, it risks unintentionally transferring antibiotic-resistant bacteria and antibiotic resistance genes (ARGs) from manure to soils. Despite the recognized environmental implications, limited research has systematically investigated the risk characteristics of ARGs linked to the combined application of manure as base fertilizer and routine irrigation practices. The question of which practice, fertilization or irrigation, more significantly contributes to the spread of ARGs remains unresolved. To bridge the gap, this study comprehensively investigates the characteristics and dissemination risks of ARGs in agricultural soils treated with chicken/cattle manure fertilization alongside groundwater irrigation. The characteristics, differences, and interactions among the resistome, microbiome, mobilome, and virulome across irrigation systems are systematically analyzed and compared. A novel non-negative matrix factorization-based microbial source tracking approach, NMF-SourceID, with superior accuracy in tracking low-abundance sources is used to quantify the source-sink relationship of ARGs in irrigated agroecosystems. The results revealed that combined fertilization and irrigation significantly enhanced both the abundance and diversity of ARGs in agricultural soils (p < 0.05). Importantly, these practices increased environmental risks by introducing emerging ARGs, mobile genetic elements, opportunistic human pathogens, virulence factors, and promoting their ecological co-occurrence. Comparative analysis showed no significant difference (p > 0.05) in ARG levels between chicken manure-treated strawberry soils and cattle manure-amended wheat cultivation soils. Source apportionment indicated that irrigation contributed 16-26% of ARGs while manure contributed 2.7-3.8%, suggesting the impact of base fertilizer on the dissemination of ARGs is much smaller than that of irrigation. The findings of this study provide essential theoretical groundwork for guiding agricultural fertilization and irrigation practices to mitigate environmental risks associated with antibiotic resistance dissemination in agroecosystems.

Agricultural irrigation is associated with antibiotic resistance gene (ARG) transmission and resistome succession through the integration of exogenous and indigenous soil communities. However, the long-term field-scale impacts of organic irrigation on vertical resistome migration and its ecological consequences remain underexplored. This study employed metagenomic analyses and field surveys to bridge these knowledge gaps. The results showed that ARGs and metal(loid) resistance genes (MRGs) were most abundant and diverse at 0-20 cm depth, with distinct characteristics in deeper layers depending on manure type. Cattle manure-irrigated soils exhibited a greater potential for vertical ARG diffusion than chicken manure-irrigated soils, despite lower surface-level enrichment. ARG distribution was more strongly associated with groundwater and soil background factors than with organic fertilizer inputs. Mobile genetic elements (MGEs) and heavy metal concentrations were key factors associated with resistome succession. Compared to the control, contigs associated with both ARGs and MRGs increased 5.8-fold and 3.1-fold in chicken and cattle manure-irrigated soils, respectively, suggesting a potentially important role for prophages. While control contigs were distributed in deeper layers, irrigated soils showed pronounced surface enrichment. Irrigation was linked to increased network density and complexity, with chicken manure-irrigated soils exhibiting higher levels of antibiotic-resistant bacteria (ARB). Notably, opportunistic pathogens carrying ARGs, including Ralstonia pickettii and Stenotrophomonas maltophilia, were enriched in irrigated profiles. Microbiome, MGEs, and abiotic factors were collectively associated with resistome succession, with deterministic processes contributing substantially to community assembly. This study provides new insights into the vertical distribution and inferred succession of the resistome in organically irrigated soils.

Soil heavy metal pollution is a persistent environmental problem because heavy metals can accumulate in soils, enter food chains, and pose long term ecological and health risks. Accurate source identification is therefore essential for targeted pollution prevention and risk management. Traditional positive matrix factorization (PMF) models rely mainly on receptor data and provide limited source information. This may weaken the interpretability of source factor correspondence in regions with strong spatial heterogeneity. To address this limitation, this study developed an integrated PMF and Geodetector framework for identifying soil heavy metal sources in Jiangxi Province, China, and for linking sources with ecological and human health risks. Six sources were identified: mineral mining (F1, 10.65%), natural background (F2, 12.57%), industrial activities (F3, 9.65%), mining associated concomitant sources (F4, 20.66%), mixed industrial, natural, and transportation sources (F5, 35.40%), and rare earth mining combined with atmospheric deposition (F6, 11.10%). Geodetector provided quantitative spatial evidence for interpreting PMF factors and reduced the uncertainty caused by empirical source matching. The risk assessment showed that mineral mining dominated by cadmium (Cd), industrial sources dominated by arsenic (As), and atmospheric deposition dominated by mercury (Hg) were the main contributors to ecological risk. Overall, 36.42%, 6.29%, and 0.92% of samples exceeded mild, moderate, and severe ecological risk levels, respectively. Health risk assessment indicated that children had higher noncarcinogenic risk than adults, with hazard quotient values of 0.26-9.21 (mean 1.56) for children and 0.04-1.48 (mean 0.26) for adults. Industrial sources dominated the major carcinogenic and noncarcinogenic risks, with As contributing >46% of total noncarcinogenic risk and As plus chromium (Cr) contributing >99% of carcinogenic risk. The results demonstrate that integrating spatial source information into PMF improves source factor mapping and provides more actionable evidence for priority source control in heterogeneous mining regions.

Urban rivers are the main water bodies humans frequently come into contact with, so the risks posed are closely monitored. Antibiotic resistance genes (ARGs) residues in reclaimed water pose serious risks to human health. There are urgent needs to improve the understanding of distribution of and risks posed by ARGs in urban rivers. In this study, shotgun metagenomic approach was used to characterize ARGs, mobile genetic elements (MGEs), and virulence factors (VFs) in water and sediment from Xinfeng River in Beijing and to identify microbes, potential antibiotic resistant bacteria, and human pathogens (HPs). MGE, microbial community, VF, and ARG co-occurrences were used to assess the environmental risks posed by ARGs. The results indicated that quinolone was the most abundant ARG type and that tufA and fusA were the two dominant ARG subtypes. Wetland effluent increased ARG abundance in the river, and the effect was detected even 50 m downstream. ARG abundances and distribution in the river had difference in different seasons. The dominant bacteria in the river were Proteobacteria, Bacteroidetes, and Actinobacteria, and 59 HPs were detected. In total, 69 MGEs and 19 VFs were found. Co-occurrence networks indicated that potential antibiotic resistant bacteria, MGEs, VFs, and ARGs in the river significantly correlated, indicating the potential risks posed by ARGs. The results improve our understanding of ARG distribution and environmental risks in urban river water. More attention should be paid to controlling environmental risks posed by ARGs in urban river and reclaimed water.

The pollution of trace elements (TEs) in soils poses significant impacts on ecosystem safety and public health. This study proposes a novel indicator (comprehensive environmental risk index, CERI), to characterize the overall pollution-ecological-health risks associated with TEs in soils, along with an integrated framework for dissecting their links with pollution sources. Within this framework, a machine learning model is constructed to predict the CERI, enabling the predictable monitoring of the overall environmental risk of soil TEs using a few conveniently obtainable parameters. Additionally, an advanced multivariate receptor model, maximum likelihood principal component analysis-nonnegative matrix factorization (MLPCA-NMF), is employed to apportion the potential sources of soil TEs. This model is validated using synthetic data and the multilinear engine 2 (ME-2). Subsequently, the apportionment results from MLPCA-NMF and ME-2 are incorporated into ecological risk and health risk assessment models to identify source-specific ecological and health risks. The application of the indicator and framework in Jiangxi Province, China, reveals that the soils in the region are polluted by Hg, Cd, Cr, and As to varying degrees, particularly in the northeast, center, and south. Notably, strong statistical correlations exist between the CERI and pollution/health risk indices. Furthermore, the random forest model provides better predictions for the CERI using five simple parameters. Agricultural activities (39.4 %-41.2 %) and industrial activities (27 %-29.2 %) are apportioned as the primary contributors of soil TEs in the area, followed by natural sources (18.7 %-19.5 %) and mixed sources (12.4 %-12.7 %). The source-specific ecological risk indicates Hg poses a significant effect, primarily attributed to sources originating from agricultural activities and industrial activities. A source-specific health risk assessment reveals that although both non-carcinogenic hazard quotients (HQ) and carcinogenic risks (CR) from soil TEs remain within acceptable thresholds, agricultural practices and mixed anthropogenic inputs show relatively higher contributions than other sources.

Reclaimed water irrigation can alleviate water resource pressure, while soil tillage is a common agricultural practice to increase crop yield. However, both of these practices may lead to the propagation of antibiotic resistance genes (ARGs). To date, there has been little research that has systematically investigated this issue. To fill this gap, this study has conducted microcosmic experiments to reveal the effect and mechanisms of using reclaimed water for irrigation and tillage treatment on the propagation of ARGs in soil, by utilizing high-throughput sequencing-based metagenomic assembly analysis approaches. The results showed irrigation significantly enhanced the abundance and diversity of ARGs in the soil. Compared to the initial soil, the total coverage of ARGs in the irrigated soil increased by 14.0 % (without tillage) to 22.7 % (with tillage). In particular, tillage treatment facilitated the enhancement of antibiotic resistome in the environment. The analysis with null model suggested soil tillage enabled ecological drift (52.4 %-66.7 %) to dominate the ARGs. Quantitative source apportionment using a machine learning-based microbial source tracking tool showed the irrigation exhibited considerable effect on the ARGs in the soil, with an average contribution of about 13.3 %-17.0 %. Network analysis revealed a close association of ARGs with mobile genetic elements (MGEs) and virulence factors, indicating potential dissemination risk of ARGs in the soil. Microbial communities, MGEs, and environmental factors collectively shaped the ARGs in the environment. Relatively, soil tillage enhanced the complex and stability of network structure and led to the colonization of ARGs in modular manner, resulting in higher contribution of ecological drift to soil resistome. Findings of this study will contribute to the management of resistome risks in reclaimed water utilization and agricultural activities for protecting soil ecosystem safety and public health.

Reclaimed water is widely used in agriculture irrigation to alleviate water scarcity, whereas the dissemination of antibiotic resistance genes (ARGs) in the soil it introduces has attracted widespread attention. Currently, few studies have systematically elucidated the coalescence of the resistome originating from reclaimed water with the soil's native community. Also, the effects and mechanisms of irrigation on the dissemination of ARGs in soils have yet to be demonstrated. To address this gap, microcosm experiments have been conducted in this study to decipher the resistome coalescence, risks and source-sink relationship of ARGs in soils irrigated with reclaimed water. The results show 237 ARGs, 55 mobile genetic elements (MGEs) and 28 virulence factors were identified in the irrigated soils. Irrigation increased the abundance and diversity of ARGs in the soil by introducing antibiotic-resistant bacteria, altering the microbial community and facilitating horizontal transfer of ARGs via MGEs, and ultimately exacerbated resistome risks in the environment. Relatively, a larger volume of irrigation water led to a more complex propagation network of the resistome. Source apportionment analysis suggested reclaimed water contributed less than 15 % of ARGs in the irrigated soils, whereas its contribution proportion increased with a larger volume of irrigation water.

The heavy metals and antibiotic resistance genes (ARGs) in landfills showed a significant correlation; however, the relationship between metal(loid) resistance genes (MRGs) and ARGs in contaminated environments, as well as whether they co-migrate with human pathogenic bacteria (HPB), remains unclear. This study is the first to report the characteristics and co-migration of ARGs and MRGs in the soil and groundwater of aged urban landfill sites. Our findings indicated that quinolone, efflux, and macrolide-lincosamide-streptogramin represented the most abundant ARGs identified. Notably, ARG abundance was higher in groundwater compared to soil, with subtype diversity reflecting a similar trend; however, microbial diversity in soil was greater. Metagenome-assembled genomes data indicated a higher risk of antibiotic-resistant HPB in groundwater. It is imperative to focus on HPB that co-carry ARGs and MRGs alongside mobile genetic elements (MGEs), such as Ralstonia pickettii and Pseudomonas stutzeri. Genes conferring resistance to copper and mercury, as well as MGEs such as qacEdelta and intI1, played a critical role in promoting horizontal gene transfer of antibiotic resistance. MRG may promote ARG migration by affecting the permeability of the cell membrane. Procrustes analysis revealed a strong similarity (87 %) between heavy metals and MRG structures. Variance partitioning analyses demonstrated that both heavy metals and biological factors jointly governed landfill ARGs (96.2 %), exerting a more substantial influence in groundwater than in soil. This study serves as a reference for managing landfill, while emphasizing the importance of addressing the co-migration of MRGs and ARGs in pathogens when controlling the spread of risks.

Electronic mediators are an effective means of enhancing the efficiency of microbial electrochemical electron transfer; however, there are still gaps in understanding the strengthening mechanisms and the efficiency of removing antibiotic resistance genes (ARGs) and antibiotic-resistant bacteria (ARB). This study systematically elucidates the effects of various electron mediators on bioelectrochemical processes, electron transfer efficiency, and the underlying mechanisms that inhibit ARG propagation within sediment microbial fuel cell systems (SMFCs). The results indicate that the addition of electron mediators significantly increased the output voltage (33.3 %-61.1 %) and maximum power density (14 %-106 %) of SMFCs, while also reducing ARB abundance and transmission risk. The enhancement effect follows the order of biochar, nanoscale zero-valent iron, graphene, and carbon nanotubes, with biochar emerging as the most economical and efficient choice for generating electricity and removing human pathogenic bacteria carrying ARGs. Procrustes analysis revealed that electron mediators facilitated the removal of ARGs by altering the structure of the microbiome, particularly the electricity-generating microorganisms (EGMs). Voltage and mobile genetic elements were the primary drivers of ARGs in the SMFCs. The network analysis results show that multiple carbohydrate-active enzymes, cluster of orthologous groups, and EGMs were negatively correlated with ARGs, indicating that the electron mediator-enhanced SMFCs mainly inhibit the spread of ARGs by promoting cell division, carbohydrate metabolism, and electricity generation. This study provides novel insights into how electron mediators affect ARG removal in microbial electrochemistry, which can inform economically viable strategies for sustainable environmental remediation.

Heavy metals (HMs) in soils pose significant risks on ecosystem and human health. To design targeted regulatory measures for mitigating and controlling the risk, it is necessary to accurately identify the pollution sources and environmental risks of soil HMs, as well as to reveal the linkages between them. To date, yet systematic investigation aimed at deciphering the links between source apportionment of soil HMs and their associated environmental risks is still lacking. To fill the gap, an integrated framework has been developed in this study and applied for dissecting the source-sink relationship and source-oriented ecological and health risks of soil HMs in Shanxi, a province with rich coal resource, in which long-term coal mining activities in history has resulted in soil HMs pollution and unavoidably posed environmental risks. Two advanced receptor models, multivariate curve resolution alternating least squares based on maximum likelihood principal component analysis (MCR-ALS/MLPCA) and multilinear engine 2 (ME2), have been employed for apportioning the potential sources, and their apportionment results are jointly incorporated into a modified ecological risk index and a probabilistic health risk assessment model for identifying the source-oriented ecological and health risks posed by soil metals. The results show that the soils in study area have been polluted by HMs (i.e., Cd, Cr, Hg and As) to varying degrees. Industrial activities (35%-35.8%), agricultural activities (11.1%-20.5%), atmospheric deposition (10.5%-13%) and mix source (31.5%-42.6%) are apportioned as the main contributors of soil HMs in the area. The source-oriented ecological risk assessment suggests Hg has presented significant ecological risk and largely contributed by the sources from atmospheric deposition and industrial activities. The source-oriented health risk assessment shows the non-carcinogenic hazard level and carcinogenic risk posed by soil HMs in the study area are acceptable. Relatively, industrial activities and mix source have contributed more on the health risks.

The discharge of wastewater into rivers can lead to resistome coalescence, thereby enhancing the spread risk of antibiotic resistance genes (ARGs) through mixing of exogenous wastewater resistome communities with indigenous riverine communities. At present, the understanding on the role of resistome community coalescence in the dissemination of ARGs is still very limited, and little is known about the process and its ecological implications. To bridge the gap, this study has conducted field-based surveys and microcosm experiments to deeply dissect the coalescence of resistome community in wastewater within river environment, utilizing genome-centric metagenomic analysis approach. The field investigation suggests resistome coalescence enhances the abundance and diversity of ARGs in the receiving river. Furthermore, the microcosm experiments reveal the effect of mixing ratio on resistome coalescence in the water-sediment system and decipher the temporal attenuation dynamics of the coalesced resistome in the environment. The results show the higher proportion of wastewater has a greater impact on ARGs in the water, whereas the effect of mixing ratio is lesser in the sediments. Temporally, the source-specific ARGs originating from wastewater exhibit decreasing trends over the experimental duration, and relatively, the attenuation in the water is more pronounced than that in the sediments. Interestingly, natural light not only facilitates the attenuation of ARGs in the water but may also induce their deposition at the water-sediment interface. Variance partitioning analyses suggest the microbiome, mobilome, and abiotic factors collectively shape the coalescence of the resistome communities in the environment. The study provides empirical evidence on resistome coalescence in river systems, which is instrumental in gaining a better understanding of the spread mechanism of ARGs in the environment.

This study is the first to explore the performance and mechanism of biochar-impacted sediment microbial fuel cell for removing antibiotic resistance genes (ARGs), and examines the effects of different biochar contents. The addition of 5% biochar produced the highest output voltage and power density, which increased by 100% and 219%, respectively, while simultaneously reducing the abundance and risk of ARGs. Comparatively, the addition of moderate amount of biochar (1-5%) promoted the removal of ARGs, while the opposite was true for excessive (10%) biochar. Biochar affected ARGs through prophages, insertion sequence, and transposons. Biological factors and voltage jointly influenced ARGs variation, with the former accounting for 56%. Further analysis of functional genes indicated that biochar controlled ARGs by regulating the synthesis of genetic material and amino acids to influence metabolism. Overall, findings of this study shed light on the potential removal of ARGs in microbial electrochemical systems.

Elucidating the formation mechanism of plastisphere antibiotic resistance genes (ARGs) on different polymers is necessary to understand the ecological risks of plastisphere ARGs. Here, we explored the turnover and assembly mechanism of plastisphere ARGs on 8 different microplastic polymers (4 biodegradable (bMPs) and 4 non-biodegradable microplastics (nMPs)) by metagenomic sequencing. Our study revealed the presence of 479 ARGs with abundance ranging from 41.37 to 58.17 copies/16S rRNA gene in all plastispheres. These ARGs were predominantly multidrug resistance genes. The richness of plastisphere ARGs on different polymers had a significant correlation with the contribution of species turnover to plastisphere ARGs β diversity. Furthermore, polymer type was the most critical factor affecting the composition of plastisphere ARGs. More opportunistic pathogens carrying diverse ARGs on BMPs (PBAT, PBS, and PHA) with higher horizontal gene transfer potential may further magnify the ecological risks and human health threats. For example, the opportunistic pathogens Riemerella anatipestifer, Vibrio campbellii, and Vibrio cholerae are closely related to human production and life, which were the important potential hosts of many plastisphere ARGs and mobile genetic elements on BMPs. Thus, we emphasize the urgency of developing the formation mechanism of plastisphere ARGs and the necessity of controlling BMPs and ARG pollution, especially BMPs, with ever-increasing usage in daily life.

Guhong injection (GHI) has been applied in the therapy of cardio-cerebrovascular disease in clinic, but there is no report about the pharmacokinetic/pharmacodynamic (PK/PD) research on GHI treating myocardial ischemia/reperfusion (MI/R) injury in rats. In this study, eight compounds of GHI in plasma, including N-acetyl-L-glutamine (NAG), chlorogenic acid (CGA), hydroxysafflor yellow A (HSYA), p-coumaric acid ( pCA), rutin, hyperoside, kaempferol-3-O-rutinoside, and kaempferol-3-O-glucoside, were quantified by LC-MS/MS. We discovered that the values of t1/2β, k12, V2, and CL2 were larger than those of t1/2α, k21, V1, and CL1 for all compounds. The levels of four biomarkers, creatine kinase-MB (CK-MB), cardiac troponin I (cTn I), ischemia-modified albumin (IMA), and alpha-hydroxybutyrate dehydrogenase (α-HBDH) in plasma were determined by ELISA. The elevated level of these biomarkers induced by MI/R was declined to different degrees via administrating GHI and verapamil hydrochloride (positive control). The weighted regression coefficients of NAG, HSYA, CGA, and pCA in PLSR equations generated from The Unscrambler X software (version 11) were mostly minus, suggesting these four ingredients were positively correlated to the diminution of the level of four biomarkers. Emax and ED50, two parameters in PK/PD equations that were obtained by adopting Drug and Statistics software (version 3.2.6), were almost enlarged with the rise of GHI dosage. Obviously, all analytes were dominantly distributed and eliminated in the peripheral compartment with features of rapid distribution and slow elimination. With the enhancement of GHI dosage, the ingredients only filled in the central compartment if the peripheral compartment was replete. Meanwhile, high-dose of GHI generated the optimum intrinsic activity, but the affinity of compounds with receptors was the worst, which may be caused by the saturation of receptors. Among the eight analytes, NAG, HSYA, CGA, and pCA exhibited superior cardioprotection, which probably served as the pharmacodynamic substance basis of GHI in treating MI/R injury.

Constructed wetlands (CWs) have been proven to effectively remove antibiotic resistance genes (ARGs) at different experimental scales; however, there is still a lack of researches on the removal and monitoring of ARGs during the actual operation of full-scale CWs. To fill this gap, this study selected the Annan constructed wetland in Beijing as a case study and utilized quantitative sequencing, metagenomic analysis, and other technical methods to determine characteristics of ARGs in CWs during different operating periods. Furthermore, we analysed the overall removal characteristics of ARGs in the CW during different operating periods and differences of ARG distribution in three media. The dominant ARGs in the CW were quinolone, β-lactam and tetracycline, with subtypes of tufA and fusA. ARG distributions are significantly influenced by anthropic activities and seasonal changes. Three periods of the CW had good removal effects on special ARGs, but there were differences in the removal characteristics of different types and subtypes of ARGs. The CW had removal effects on four types of ARGs (such as multidrugs), 16 types of fusidic acid, and nine types of ARGs (such as bleomycin) during the dormancy, start-up, and operation periods, respectively. Among ARG subtypes, the CW had removal effects on 37, 53, and 51 subtypes during the dormancy, start-up, and operation periods, respectively. The subtypes that were removed mainly included those containing tetracycline, efflux pump, and β-lactam, mcr-1, and mcr-5 (colistin ARGs). For individual parts of CWs, the removal effects on the total abundance of ARGs were as follows: forebay > surface flow wetland > subsurface flow wetland. These findings provide insights for optimizing the purification efficiency of CWs for ARGs.

The source diversity and health risk of trace elements (TEs) in soil make it necessary to reveal the relationship between pollution, source, and risk. However, neglect of spatial heterogeneity restricts the reliability of existing identification methods. In this study, spatial heterogeneity is proposed as a necessary and feasible factor for accurately dissecting the pollution-source-risk link of soil TEs. A comprehensive framework is developed by integrating positive matrix factorization, Geodetector, and risk evaluation tools, and successfully applied in a mining-intensive city in northern China. Overall, the TEs are derived from natural background (28.5%), atmospheric deposition (25.6%), coal mining (21.8%), and metal industry (24.1%). The formation mechanism of heterogeneity for high-variance TEs (Se, Hg, Cd) is first systematically deciphered by revealing the heterogeneous source-sink relationship. Specifically, Se is dominated (76.5%) by heterogeneous coal mining (q=0.187), Hg is determined (92.6%) by the heterogeneity of metal mining (q=0.183) and smelting (q=0.363), and Cd is caused (50.9%) by heterogeneous atmospheric deposition (q>0.254) co-influenced by the terrains and soil properties. Highly heterogeneous sources are also noteworthy for their potential to pose extreme risks (THI=1.122) in local areas. This study highlights the necessity of integrating spatial heterogeneity in pollution and risk assessment of soil TEs.

Antibiotic resistance has received widespread attention in recent years. Soil irrigation and fertilization are routine agricultural practices, but also lead to the spread of antibiotic resistance genes (ARGs) in soil-crop system such as via resistome coalescence. Despite community coalescence being ubiquitous and important in natural ecosystems, little research has been done to investigate resistome coalescence during soil irrigation activities. In this study, the characteristics of antibiotic resistome and community coalescence in the soils irrigated with different irrigation materials (wastewater, wastewater-river water, and wastewater-manure) have been revealed by utilizing microcosm experiments and high-throughput sequencing-based metagenomic assembly approaches. Results showed irrigation and coalescence changed soil quality and resistome. Totally, 789 unique ARGs were identified in the irrigation system, including some emerging ARGs. The abundance and diversity of ARGs increased in the coalesced soils, mainly due to the newly imported ARGs from irrigation materials. Relatively, the soils irrigated with wastewater and manure showed higher level of ARGs. Irrigation with the mixtures containing river water caused greater loss of indigenous taxa, while the community structure of mixing treatment with manure changed more dramatically. Interestingly, the succession of community in coalesced soils was influenced by transient competition for resources and ecological niche width, and the highest abundance and diversity of microorganisms and ARGs were found in the initial phase of coalescence, followed by a gradual succession towards the original community. With increasement of wastewater in the irrigation materials, the soil community showed a stepwise change rather than linear change. Notably, natural deposit of irrigation materials reduced their impacts on the ARGs in the coalesced soils. Findings provide new insights into the resistome coalescence during agricultural practices for reducing the spread risks of ARGs.

Heavy metals in soils pose serious ecological and health risks. To make efficient strategies for mitigating the underlying hazards, it is critical to reveal the pollution sources and their links with the risks. Researchers have investigated source identification and risk evaluation of heavy metals in soils, yet few have systematically deciphered the source-sink relationship of soil metals and the links between source apportionment and risk assessment. In the study, an integrated technological framework has been proposed to address the gaps, and applied to characterize the pollution risks, sources and their links of soil metals in a typical coal resource city in China. The assessment using geochemical tool and ecological risk index shows the soils in study area are polluted by Cd, Hg, Cr, As and Pb in varied degrees, and particularly, Cd and Hg present significant ecological risk. Two advanced receptor models (multivariate curve resolution-weighted alternating least-squares and multilinear engine 2) are comparatively applied for apportioning the potential sources of soil metals, and the results suggest the two models have identified similar sources (r(2) > 0.90), including agricultural activities, atmospheric depositions and industrial discharges with contributions of 35.5 %-38.3 %, 30.3 %-35.1 %, and 26.6 %-34.1 %, respectively. Then, apportionment results of the two models are jointly employed for evaluating the sourcespecific health risks of metals in the environment using a probabilistic risk assessment model. The risk levels within the area are overall acceptable or tolerable, and relatively, the industrial discharges present higher contribution on the non-carcinogenic and carcinogenic risks of soil metals to public. Findings will help the managers to design targeted policies for reducing the risks of soil metals, and the framework proposed provides a useful guideline to better understand the source-risk relationship of soil metals in other environments worldwide.

Excessive levels of heavy metals in soil can significantly impact human health and ecological safety. Evaluating heavy metal pollution and identifying its sources are crucial for environmental management. This study investigates the status of heavy metal pollution in a southeastern region of China and aims to identify its sources using data from the first national soil pollution survey, which includes 282 sampling points. Indicators such as the geoaccumulation index (Igeo), the potential ecological risk index (RI), the hazard index (HI), and the total lifetime cancer risk (TLCR) were utilized to assess contamination levels. Geographic information systems (GIS), positive matrix factorization (PMF) receptor modeling, cluster analysis (ClusA) and human health risk assessments were integrated to analyze the sources of heavy metals. The results indicate that agricultural pollution sources have a minor impact on overall heavy metal contamination, with low ecological risk levels in the eastern and western regions. In contrast, the central region exhibited moderate risk, with areas of extremely high risk distributed across the central-west and central-south regions. PMF analysis identified pollution sources including natural origins, coal combustion, industrial emissions, and traffic, with contributions of 17.62%, 18.50%, 28.35%, and 35.56%, respectively. Overall, the carcinogenic risk in the study area is not high. Targeted recommendations were made in response to the pollution situation in the study area. This research enhances our understanding of heavy metal pollution in the soil of the study area and provides a reference for pollution source delineation in other regions.

Irrigation and fertilization are the routinely agricultural practices but also cause resistome coalescence, by which the entire microbiomes from irrigation materials invade soil microbial community, to transfer antibiotic resistance genes (ARGs) in the coalesced soils. Although studies have reported the effect of irrigation or fertilization on the prevalence and spread of ARGs in soils, risk characteristics of resistome coalescence in irrigation system remain to be demonstrated and few has shown whether natural storage of irrigation materials will reduce resistance risks. To fill the gaps, two microscopic experiments were conducted for deeply exploring resistance risks in the soils irrigated with wastewater and manure fertilizer from a perspective of community coalescence by metagenomic analysis, and to reveal the effect of natural storage of irrigation materials on the reduction of resistance risks in the coalesced soils. Results showed irrigation and coalescence significantly increased the abundance and diversity of ARGs in the soils, and introduced some emerging resistance genes into the coalesced community, including mcr-type, tetX, qacB, and an array of genes conferring resistance to carbapenem. Procrustes analysis demonstrated microbial community was significantly correlated with the ARGs in coalesced soils, and variance partitioning analysis quantified its dominant role on shaping resistome profile in the environment. Besides ARGs, abundant and diverse mobile genetic elements (MGEs) were also identified in the coalesced soils and co-existed on the ARG-carrying contigs, implying potential transfer risk of ARGs in the irrigation system. Further, the analysis of metagenome-assembled genomes (MAGs) confirmed the risk by recovering 358 ARGs-carrying MAGs and identifying the resistant bacteria that co-carried multiple ARGs and MGEs. As expected, the natural storage of irrigation water and manure fertilizer reduced about 27%-54% of ARGs, MGEs and virulence factors in the coalesced soils, thus caused the soils to move towards lower resistance risks to a certain extent.