Rural revival: Navigating environmental engineering and technology.

The necessity for global engineering and technological solutions to address rural environmental challenges is paramount, particularly in improving rural waste treatment and infrastructure. This study presents a comprehensive quantitative analysis of 3901 SCI/SSCI and 3818 Chinese CSCD papers, spanning from 1989 to 2021, using tools like Derwent Data Analyzer and VOSviewer. Our key findings reveal a significant evolution in research focus, including a 716.67% increase in global publications from 1995 to 2008 and a 154.76% surge from 2015 to 2021, highlighting a growing research interest with technological hotspots in rural revitalization engineering and agricultural waste recycling. China and the USA are pivotal, contributing 784 and 714 publications respectively. Prominent institutions such as the Chinese Academy of Sciences play a crucial role, particularly in fecal waste treatment technology. These insights advocate for enhanced policy development and practical implementations to foster inclusive and sustainable rural environments globally.

Mitigating Tetracycline antibiotic contamination in chicken manure using ex situ fermentation system.

Excessive use of tetracycline antibiotics in poultry farming results in significant concentrations of these drugs and tetracycline resistance genes (TRGs) in chicken manure, impacting both environmental and human health. Our research represents the first investigation into the removal dynamics of chlortetracycline (CTC) and TRGs in different layers of an ex situ fermentation system (EFS) for chicken waste treatment. By pinpointing and analyzing dominant TRGs-harboring bacteria and their interactions with environmental variables, we've closed an existing knowledge gap. Findings revealed that CTC's degradation half-lives spanned 3.3-5.8 days across different EFS layers, and TRG removal efficiency ranged between 86.82% and 99.52%. Network analysis highlighted Proteobacteria and Actinobacteria's essential roles in TRGs elimination, whereas Chloroflexi broadened the potential TRG hosts in the lower layer. Physical and chemical conditions within the EFS influenced microbial community diversity, subsequently impacting TRGs and integrons. Importantly, our study reports that the middle EFS layer exhibited superior performance in eliminating CTC and key TRGs (tetW, tetG, and tetX) as well as intI2. Our work transcends immediate health and environmental remediation by offering insights that encourage sustainable agriculture practices.

Enhancing sorption of layered double hydroxide-based magnetic biochar for arsenic and cadmium through optimized preparation protocols.

The impact of multiple preparation protocols on properties and performance of modified biochar remains unclear. This study prepared layered double hydroxide (LDH)-based magnetic biochars (LMBCs) with different LDH loading rates (LLR), pyrolysis temperatures, and biomass sources to explore their performance-characterization relationships toward As(III) and Cd(II). Higher LLR and pyrolysis temperature enhanced LMBCs᾿ adsorption capacities by increasing specific surface area (SSA) and metal/O-containing groups. Hence, LMBC produced at 2:1 LLR (LDH: magnetic biochar) and 800 ℃ pyrolysis exhibited maximum adsorption over 2 times that of LMBC with 0.5:1 LLR and 400 ℃ pyrolysis. Bamboo-sourced LMBC demonstrated superior adsorption than sewage sludge and garlic-sourced LMBCs due to its increased SSA, enabling a higher loading of nano-LDH. Adsorption of As(III) and Cd(II) onto LMBCs was governed by metal-mineral and metal-containing group through co-precipitation and complexation. This study provides a reference for adjusting the preparation protocols to improve sorption performance of modified biochar toward multiple heavy metals.

Pig manure-derived fulvic acid more strongly drives the fate of arsenic and antibiotic resistance genes in paddy soil.

Antibiotic resistance genes (ARGs) can threaten the clean production of rice owing to continuous selective pressure in heavy metal-antibiotic co-contaminated paddy soils. As an important soil carbon reservoir, the role of humic substances from different types of manure in the regulation of soil ARGs remains unclear. In this study, fulvic acid (FA) and humic acid (HA) were extracted from pig manure (PM), cow dung (CD), and chicken manure (CM). The influence of their characteristics and doses on the fate of ARGs was investigated in arsenic (As)-antibiotic co-contaminated paddy soils. The release of As and degradation of antibiotics were promoted in 1% PM-FA treatment, with increases of 4.8%-5.6% and 8.3%-8.8% compared with CM-FA and CD-FA treatments, respectively. The coexistence of FA/HA, Fe, As, and antibiotics in soil pore water affected the environmental behavior of ARGs, with FA showing a more positive effect. Species including Bacillus, Geobacter, Desulfitobacterium, and Christensenellaceae_R-7_group were considered potential hosts of ARGs, and their resistance to co-contamination increased after the addition of FA. Membrane transport is a potential strategy for host bacteria of ARGs to cope with As-antibiotic complex pressure. These results demonstrate the coupling mechanisms of As, antibiotics, and ARGs regulated by different humic substances in co-contaminated paddy soils, which could support the clean production of rice in agricultural practice.

The Eco-Agricultural Industrial Chain: The Meaning, Content and Practices.

Lucid waters and lush mountains are invaluable assets. Resource-saving and environmentally friendly industrial structures, production, and living modes are pursued continuously for sustainable ecological development. According to the Second National Pollution-Source Survey, agricultural non-point pollution is still the most important source of the current water pollution. In order to improve the water environment and control the pollution, the meaning and content of the eco-agricultural industrial chain was introduced. Based on this conception, the eco-agricultural industrial chain, integrating a whole circular system with different sessions of crop farming, animal breeding, agricultural product processing, and rural living, was innovatively put forward to control the agricultural non-point pollution and protect the water environment systematically for the first time in this paper. The sustainable development was realized at a large scale from the reduction and harmlessness at the source, resource utilization in the process, and ecological restoration in the end. Core techniques were innovated based on the integration of agricultural industries to achieve the high-quality and green development of agriculture. The system included ecological breeding technologies, ecological cultivation technologies, as well as rural sewage treatment and recycling technologies, in the principle of reduce, reuse, and resource. Based on this, the agricultural production changed from the traditional mode of "resources-products-wastes" to the circulation pattern of "resources-products-renewable resources-products". Thus, the final aim could be achieved to realize the material's multilevel use and energy conversion in the system. The eco-agricultural industrial chain technology was proven to be efficient to achieve both the good control of agricultural non-point pollution and an effective improvement in the water quality.

Bacterial dynamics and functions driven by biomass wastes to promote rural toilet blackwater absorption and recycling in an ectopic fermentation system.

Due to high concentration of organic matter and the ease of disease transmission, blackwater pose a serious threat to both the environment and human health, especially in rural areas where wastewater treatment is dispersed. The reuse of biomass waste is also a difficult issue to be addressed urgently. In this study, an ectopic fermentation system (EFS) was used to treat toilet blackwater, and the effects of different biomass waste combinations on bacterial communities and functions during aerobic fermentation of blackwater were compared. The results showed that adding bran powder prolonged the high temperature period of 11 d, improved blackwater absorption capacity by 7.5% and was beneficial to microbial metabolic activities to enhance organic degradation. By contrast, the combination of corn straw and rice husk obtained abundant bacterial OTUs and diversity. Bacillus, Thermobifida and Thermopolyspora were the main microorganisms involved in the degradation of organic matter in EFS, and their abundance varied in different filler combinations. Bacterial communities were directly affected by environmental factors such as temperature, NH4+-N and organic carbon as well as biomass materials during fermentation. This study revealed the role of corn straw, rice husk and bran powder in EFSs, provided new technical support for blackwater treatment and a new direction for the resource utilization of agricultural biomass waste.

Ternary Ca-Mg-Al layered double-hydroxides for synergistic remediation of As, Cd, and Pb from both contaminated soil and groundwater: Characteristics, effectiveness, and immobilization mechanisms.

Layered double hydroxides (LDH) are the cost-effective and high-efficiency materials for remediation of potentially toxic elements (PTEs) in contaminated soil and groundwater. Herein, the effectiveness and mechanisms of a ternary Ca-Mg-Al LDH (CMAL) for the synergistic remediation of As, Cd, and Pb were investigated in contaminated soils and simulative groundwaters for the first time. The immobilization efficiencies of As, Cd, and Pb in both black soil (BS) and red soil (RS) amended by CMAL at 5 wt% were all > 75%. CMAL amendment transferred more mobile As, Cd, and Pb fractions in soils to immobile species than did Ca-Al LDH and Mg-Al LDH treatments. Furthermore, using a pump-and-treat technology, 82-98% of these 3 PTEs from contaminated groundwater were successfully immobilized in both CMAL treated BS and RS top-soils. Meanwhile, leaching of Ca, Mg, and Al from CMAL was minimal indicating the material was stable. The excellent immobilization performance of CMAL for these PTEs was attributed to the coating of soil microparticles by CMAL nanosheets that allowed complexation of Ca-O-As/Cd or Mg-O-As/Cd/Pb formation, co-precipitation of Ca/Fe-As and Cd(OH)2, and formation of Ca-bridged ternary complex (FeO-Ca-As/Cd). The adverse effect of oppositive pH/Eh-dependence between As and Cd/Pb was overshadowed by these mechanisms and thus allowed As immobilization. Immobilization of As, Cd, and Pb by CMAL amendment was more favorable for RS soil due to its lower reduction potential and more participation of metal-(hydr)oxides for complexation. Overall, the ternary-LDH is a promising synergistic remediation strategy for multi-PTEs contaminated soil and groundwater.

Manure application facilitated electrokinetic remediation of antibiotic-arsenic co-contaminated paddy soil.

The co-existence of antibiotics and heavy metals in soil with manure application poses high risk to both environment and human health, and thus effective remediation methods are in urgent need. This study investigated the synergistic effects of electrokinetic remediation (EKR) on antibiotic resistance and arsenic (As) in co-contaminated paddy soils. EKR treatments in soil amended with pig manure (EKR-PD) showed better remediation efficiency compared with that without pig manure. In detail, the content of available As and the abundance of antibiotic-resistant bacteria (ARB) decreased by 25.2 %-41.4 % and 9.5 %-21.1 % after 7-d remediation, respectively, due to a relatively higher current density for EKR-PD. The role of the electric field contributed to 33.9 % of antibiotic degradation. Antibiotic resistance genes (ARGs) with ribosomal-protection and enzymatic-deactivation types were easier to remove, with the removal ratio of 37.8 %-41.6 % in EKR-PD. Brevundimonas was the most significantly different species during remediation. Bacillus and Clostridium_ sensu_stricto_1 were potential host bacteria of ARGs in the electric field. Membrane transport might be an effective strategy for microorganisms to respond to the stress of both electric field and co-contaminated environments. This study supports the potential role of EKR in the co-contamination of heavy metals and antibiotic resistance under manure application.

Controlling AMR in the Pig Industry: Is It Enough to Restrict Heavy Metals?

Heavy metals have the potential to influence the transmission of antimicrobial resistance (AMR). However, the effect on AMR caused by heavy metals has not been clearly revealed. In this study, we used a microcosm experiment and metagenomics to examine whether common levels of Cu and Zn in pig manure influence AMR transmission in manured soil. We found that the abundance of 204 ARGs significantly increased after manure application, even though the manure did not contain antibiotic residuals. However, the combined addition of low Cu and Zn (500 and 1000 mg/kg, respectively) only caused 14 ARGs to significantly increase, and high Cu and Zn (1000 and 3000 mg/kg, respectively) caused 27 ARGs to significantly increase. The disparity of these numbers suggested that factors within the manure were the primary driving reasons for AMR transmission, rather than metal amendments. A similar trend was found for biocide and metal resistance genes (BMRGs) and mobile genetic elements (MGEs). This study offers deeper insights into AMR transmission in relation to the effects of manure application and heavy metals at commonly reported levels. Our findings recommend that more comprehensive measures in controlling AMR in the pig industry are needed apart from restricting heavy metal additions.

Performance exploration and microbial dynamics of urine diverting composting toilets in rural China.

The ongoing "toilet revolution" in China provides new opportunities to improve the rural living environment and sanitation, and the introduction of new sanitation facilities such as urine diverting composting toilets (UDCTs) is conducive to the effective treatment and resource utilization of feces. This study revealed the degradation performance and microbial community dynamics of UDCTs and clarified the influence mechanism of fecal volume in aerobic composting treatment. The results showed that UDCTs could effectively decompose human feces, with an organic matter degradation rate of 25%⁓30%. The temperature, water content, NH4+-N and nutrient accumulation were higher in the high fecal volume treatment than in the low fecal volume treatment. Bacterial community composition and structure in UDCTs varied with composting stage and fecal volume. The diversity and richness of bacterial community in compost were changed with different fecal volumes, but the dominant groups were similar. Redundancy analysis (RDA) showed that nitrogen and organic carbon were the main drivers of bacterial community changes during composting. Highly nutritious and non-phytotoxic compost products were suitable for agronomic uses. Based on these results, UDCTs can be an effective way to solve the problem of fecal pollution in rural areas, and fecal dosage is a potential influencing factor in the operation and maintenance of composting systems.

Effect of three aging processes on physicochemical and As(V) adsorption properties of Ce/Mn-modified biochar.

Modified biochar used for soil remediation is affected by exposure to the environment and aging process results in changes in its physicochemical properties and As(V) adsorption and immobilization in soil. Herein, the Ce/Mn-modified wheat straw-biochar (MBC) was manufactured and then aged through three artificial aging processes by exposure to soil with additional natural, freeze-thaw, and dry-wet cycles involved. It revealed that the specific surface areas of freeze-thaw-aged MBC reached 214.98 m2/g and was increased more than those of other two aging treatments. In addition, the pH values and C contents of MBC all decreased after aging while the H and O contents increased. Correspondingly, the contents of O-containing functional groups like C-O, -OH, and CO all increased by >16% with aging. The freeze-thaw cycling and alternating dry-wet aging treatments improved adsorption capacities of As(V) onto MBC and were increased by 16.2 and 10.6% at pH 5, respectively and these samples exhibited the best recyclability and adsorption selectivity for As(V). However, natural aging exerted a lower effect for As(V) adsorption by MBC due to its few changes on physicochemical properties. Causally, the freeze-thaw and dry-wet aging activated the Ce/Mn-oxides to generate Mn2+/3+ species and a new mono-Ce that exerted a strong bonding complexation with As(V) to form Ce/Mn-O-As ligands and increased CeAsO4 precipitation. Our results offer a new insight into the alterations expected for modified biochars with aging treatment in terms of As(V) adsorption for its long-term utilization in As contaminated soil.

Profiles of antibiotic- and heavy metal-related resistance genes in animal manure revealed using a metagenomic analysis.

Farmed animals produce excrement containing excessive amounts of toxic heavy metals as a result of consuming compound feed as well as receiving medical treatments, and the presence of these heavy metals may aggravate the risk of spreading drug-resistance genes through co-selection during manure treatment and application processes. However, research on the association between heavy metals and antimicrobial resistance is still lacking. In this study, metagenomic sequencing was used to explore the effects of the co-selection of environmentally toxic heavy metals on the resistome in manure. A relevance network analysis showed that metal-resistance genes (MRGs), especially for copper (Cu) and zinc (Zn), were positively correlated with multiple types of antibiotic-resistance genes (ARGs) and formed a complex network. Most bacteria that co-occurred with both MRGs and ARGs simultaneously are members of Proteobacteria and accounted for 54.7% of the total microbial species in the relevance network. The remaining bacteria belonged to Firmicutes, Bacteroidetes and Actinobacteria. Among the four phyla, Cu- and Zn-resistance genes had more complex correlations with ARGs than other MRG types, reflecting the occurrence of ARG co-selection under the selective pressure of high Cu and Zn levels. In addition, approximately 64.8%, 59.1% and 68.4% of MRGs that correlated with the presence of plasmids, viruses and prophages, respectively, are Cu- or Zn-resistant, and they co-occurred with various ARGs, indicating that mobile genetic elements participate in mediating ARG co-selection in response to Cu and Zn pressure. The results indicated that the use of heavy-metal additives in feed induces the increases of drug resistance genes in manure through co-selection, aggravating the risk of antimicrobial resistance diffusion from animal farm to manure land applications.

Impact of different manure-derived dissolved organic matters on the fate of arsenic-antibiotic in co-contaminated paddy soils.

Manure application increases the transfer risk of antibiotic resistance to farmland. Especially, its impact remains unclear when it occurs in arsenic (As)-contaminated paddy soils, which is considered as a global environmental problem. In this work, we investigated the fate of antibiotic resistance genes (ARGs) in As-antibiotic co-contaminated paddy soils under the application of manure from different sources (pig manure, cow dung, and chicken manure). Differences in the aliphatic carbon and electron-donating capacities of these dissolved organic matters (DOM) regulated the transformation of iron and As by both biotic and abiotic processes. The regulation by pig manure was stronger than that by cow dung and chicken manure. DOM regulation increased the abundance of As-related functional genes (arsC, arrA, aioA, and arsM) in the soil and accelerated the transformation of As speciation, the highest proportion of As(III) being 45%-61%. Meanwhile, the continuous selection pressure provided by the highly toxic As(III) increased the risk of ARGs and mobile genetic elements (MGEs) via horizontal gene transfer. As-resistant bacteria, including Bacillus, Geobacter, and Desulfitobacterium, were finally considered as potential host bacteria for ARGs and MGEs. In summary, this study clarified the synergistic mechanism of As-antibiotic on the fate of ARGs in co-contaminated paddy soils, and provided practical guidance for the proper application of organic fertilizers.

Dynamics of a Bacterial Community in the Anode and Cathode of Microbial Fuel Cells under Sulfadiazine Pressure.

Microbial fuel cells (MFCs) could achieve the removal of antibiotics and generate power in the meantime, a process in which the bacterial community structure played a key role. Previous work has mainly focused on microbes in the anode, while their role in the cathode was seldomly mentioned. Thus, this study explored the bacterial community of both electrodes in MFCs under sulfadiazine (SDZ) pressure. The results showed that the addition of SDZ had a limited effect on the electrochemical performance, and the maximum output voltage was kept at 0.55 V. As the most abundant phylum, Proteobacteria played an important role in both the anode and cathode. Among them, Geobacter (40.30%) worked for power generation, while Xanthobacter (11.11%), Bradyrhizobium (9.04%), and Achromobacter (7.30%) functioned in SDZ removal. Actinobacteria mainly clustered in the cathode, in which Microbacterium (9.85%) was responsible for SDZ removal. Bacteroidetes, associated with the degradation of SDZ, showed no significant difference between the anode and cathode. Cathodic and part of anodic bacteria could remove SDZ efficiently in MFCs through synergistic interactions and produce metabolites for exoelectrogenic bacteria. The potential hosts of antibiotic resistance genes (ARGs) presented mainly at the anode, while cathodic bacteria might be responsible for ARGs reduction. This work elucidated the role of microorganisms and their synergistic interaction in MFCs and provided a reference to generate power and remove antibiotics using MFCs.

Influences of human waste-based ectopic fermentation bed fillers on the soil properties and growth of Chinese pakchoi.

The reuse of human wastes as biofertilizer resources offers a new option for meeting the growing demand for food and addressing poor soil productivity. Feces and black water are ubiquitous human wastes that usually require proper treatment, such as composting and anaerobic digestion, to remove potentially harmful substances before they can be applied as fertilizers. As an effective treatment technology for livestock farming wastes, the ectopic fermentation bed system (EFS) provides a new means of treating human waste and producing organic fertilizer from decomposed filler. Therefore, the objective of this study was to evaluate and compare the nutrient content and fertilizer potential of decomposed fillers obtained after EFS treatment of human feces and black water under different application conditions. The results showed that the application of fillers increased the yield of pakchoi by 3.60⁓29.32% and nutrient uptake by 8.09⁓83.45% compared to the CK, which could effectively promote the growth of pakchoi. This approach also improved the quality of pakchoi and enhanced soil fertility, and differences were observed in the effects of different kinds and application amounts of fillers. Soil EC was the soil property that had the greatest effect on the growth characteristics of pakchoi in this study. These findings help to better clarify the agronomic value of human wastes, but the effects of long-term filler application need to be further explored.

[Effects of Earthworms/Biochar on Bacterial Diversity and Community in As-contaminated Red Soil].

Cerium-manganese modified biochar (MBC) combined with earthworms (Eisenia foetida) can immobilize arsenic (As) in red soils. In this study, high-throughput sequencing technology was used to explore the combined effects of MBC and E. foetida on bacterial diversity and community structure in As-contaminated red soils. The results showed that the single earthworm treatment had the highest diversity index, whereas the diversity index decreased in the single biochar or MBC treatment, indicating that earthworms can boost the growth of bacteria in the soil, and the addition of biochar/MBC all decreased the bacterial diversity of soils. When biochar/MBC was combined with earthworms, the diversity index increased to some degree. In terms of bacterial community structure, the relative abundance of Proteobacteria and Bacteroidetes increased significantly in each treatment, especially for MBC-earthworm treated soil, in which the relative abundance was increased by 17.08% and 329.47% for Proteobacteria and Bacteroidetes, respectively, compared to that in the control (CK). Otherwise, those abundances were decreased by 19.18% and 48.76%, respectively, for Acidobacteria and Chloroflexi. Correlation analysis results showed that the soil water-soluble As (WSAs) was negatively correlated with the relative abundances of Proteobacteria and Bacteroides (P<0.05) but was positively correlated with Acidobacteria and Chloroflexi (P<0.05), which indicated that with the decrease in WSAs in soils, the bacteria of Proteobacteria and Bacteroides reproduced rapidly, whereas the Acidobacteria and Chloroflexi were inhibited. Moreover, different treatments induced selective changes in the bacterial community, in which earthworms significantly promoted the proliferation of γ-Proteobacteria, Flavobacteriales, Aeromonadales, and Variovorax and earthworms improved the immobilization effect of As by promoting the growth of these bacteria.

Pre-magnetic bamboo biochar cross-linked CaMgAl layered double-hydroxide composite: High-efficiency removal of As(III) and Cd(II) from aqueous solutions and insight into the mechanism of simultaneous purification.

Trivalent arsenic (As(III)) and divalent cadmium (Cd(II)) contamination in water environment is an urgent issue because of their most toxic physicochemical properties. Herein, the simultaneous purification of As(III) and Cd(II) from aqueous solution was achieved by use of a pre-magnetic Fe modified bamboo biochar that cross-linked CaMgAl layered double-hydroxide composite (Fe-BC@LDH). In a binary system, adsorption equilibrium of As(III) and Cd(II) onto specific sorbent Fe-BC@LDH was reached within 100 and 10 min of contact time under anaerobic conditions, respectively, and the maximum adsorption capacities of As(III) and Cd(II) by Fe-BC@LDH were respectively calculated to be ⁓265.3 and ⁓320.7 mg/g at pH 4.5 and 5- and 14-times than that of unmodified biochar. Moreover, adsorption in a competitive or single system, the sorbent displayed a greater preference for Cd(II). Importantly, the removal of As(III) and Cd(II) onto the composite was more favorable in a binary system due to formation of ternary FeOCdAs bonding configuration as well as the redox transformation of As(III) to As(V), inner-sphere complexation of MOAs/Cd (MFe, Ca, Mg, Al), electrostatic attraction, and co-precipitation of scorodite and hydroxy­iron­cadmium. Furthermore, the nanocomposite was still highly efficient after 5 adsorption cycles. This study demonstrated that the synthesized cost-effective Fe-BC@LDH is a promising candidate for the simultaneous separation of As(III) and Cd(II) from wastewater.

Cu and Zn exert a greater influence on antibiotic resistance and its transfer than doxycycline in agricultural soils.

Livestock manure is a main source of heavy metals, antibiotics and antibiotic resistance genes (ARGs) in agricultural soils. The co-existence of heavy metals and ARGs needs to be systematically studied, since manure application is greatly encouraged. In this study, we examined soils for alterations in antibiotic resistance where doxycycline, Cu, and Zn were added equivalent to those found in typical pig manure applications. The results indicated that high levels of Cu inhibited soil respiration and urease for the first 10 days. Metagenomic analysis demonstrated that Cu and Zn additions caused profound alterations in bacterial community, metal resistance genes (MRGs) and mobile genetic elements. Among the differential ARGs, efflux pump genes took a significantly high ratio compared with control for the first 5 days, emphasizing their important roles in the profile of antibiotic resistance. Moreover, the number of differential MRGs was < 30 for doxycycline treatment, but 66-87 for Cu and Zn treatments. The number of differential integrative and conjugative elements was 3 for doxycycline treatment, and 6-13 for Cu and Zn treatments. Overall, high Cu and Zn levels caused a greater influence than did doxycycline on bacterial communities and transfer of antibiotic resistance in soil.

[Effect of Manure from Different Sources on the Leaching of Antibiotics in Soil].

Antibiotic residues in farmland soils resulting from the application of livestock manure poses risks to the soil and water ecology associated with the spread of antibiotic resistance, thereby threatening environmental safety and human health. Here, a leaching experiment was carried out using soil(CK-T), pig manure(PM-T), cow manure(CM-T), and chicken manure(CHM-T) with the addition of tetracyclines(tetracycline, oxytetracycline, and chlortetracycline) and a control group(without antibiotics). The effects of different sources of manure on soil physical and chemical indicators and bacterial abundance under simulated leaching conditions were studied, while the migration of tetracyclines in the different treatments were also determined. The results showed that compared with the CHM-T and CM-T treatments, the tetracyclines in the PM-T treatment were more easily accumulated in the soil(residual amounts=0.90-6.91 mg·kg-1 compared to the other treatments=0.33-4.42 mg·kg-1). Compared with the surface soil(0-4 cm), higher concentrations of tetracyclines were detected at soil depths of 16-24 cm. Consistent with the residues of antibiotics, the concentrations of TN and NH4+-N in the soil with the PM-T treatment were increased by 0.044 g·kg-1 and 14.11 mg·kg-1, respectively, which were significantly higher than other treatments. The abundance of bacteria in the soil was reduced due to the bactericidal effect of antibiotics, by 39.66% in the PM-T treatment, which was significantly higher than in the other treatments(12.38%-35.26%). Compared with other treatments, the antibiotics in the CHM-T treatment were more easily leached from the soil, with 9.91 mg of antibiotics in the leachate, which was significantly higher than the other treatments(P<0.05). TN, NH4+-N, tetracycline, oxytetracycline, and chlortetracycline were the first principal component factors, accounting for 54.55% of the variation, and corresponding concentrations increased with soil depth. Based on these results, tetracyclines in pig manure tended to accumulate in soil and transfer vertically along with variations in the soil microbial community. For chicken manure, relatively high concentrations of tetracyclines were detected in the soil leachate, increasing the risk of water pollution.

Differential effects of sulfamethoxazole concentrations on the enzymatic dynamics of aerobic composting.

Enzymatic activities play an important role in the biological composting processing of agricultural wastes. This paper explores the effect of sulfamethoxazole (SMX) (Control, 25 mg/kg, 50 mg/kg, and 100 mg/kg) on the enzymatic activities of cellulase, protease, urease, and arylsulfatase. Compost samples were taken at three different intervals for analysis (day 0, day 25, and day 45). The findings revealed that at the start of the composting process, a strongly negative effect on enzymatic behavior was observed, and this response was significantly dependent on SMX concentrations (p < 0.05). The inhibition was consistent across all treatments. According to the results, the negative impact of SMX on community structure can result in selection pressure. Furthermore, all of the treatments had drastically improved enzymatic activity by the end of the composting process (day 45). This effect was presumably caused by the deterioration of SMX and a substantial stress reduction.