Identifying synergistic solutions for the food-energy-water nexus via plastic film mulching cultivation.

Food security, water scarcity, and excessive fossil energy use pose considerable challenges to sustainable agriculture. To understand how rain-fed farming systems on the Loess Plateau, China, reconcile yield increases with ecological conservation, we conducted an integrated evaluation based on the denitrification-decomposition (DNDC) model, agricultural statistics data using the Food-Energy-Water (FEW) nexus indicator. The results showed that maize yields with ridge-furrow plastic film mulching (PFM) were 3479, 8942, and 11,124 kg ha-1 under low (50 kg N ha-1), medium (200 kg N ha-1), and high (350 kg N ha-1) nitrogen (N) fertilizer rates, respectively, and that PFM increased yield and water use efficiency (WUE) by 110-253 % and 166-205 % compared to using no mulching (control, CK), respectively. Plastic film mulching also increased net energy (126-436 %), energy use efficiency (81-578 %), energy productivity (100-670 %), and energy profitability (126-994 %), and nitrogen fertilizer, compound fertilizer, and diesel fuel consumption by agricultural machinery were the main energy inputs. The PFM system reduced water consumption during the maize growing season and the green water footprint and gray water footprint decreased by 66-74 % and 44-68 %, respectively. The FEW nexus indicator, based on a high production at low environmental cost scenario, was greater under the PFM system and had the widest spatial distribution area at the medium-N application rate. Among the environmental factors, the nexus indicator was negatively correlated with precipitation (-0.37), air temperature (-0.36), and the aridity index (-0.36), but positively correlated with elevation (0.17). Our results suggest that the PFM system promotes resource-saving while increasing yields and moves dryland agriculture in an environmentally friendly direction, thus promoting the sustainable development of agroecosystems.

Adsorption and desorption of Hg(II) by four aged microplastics and its effects on gaseous elemental mercury production in seawater.

Microplastics (MPs) weather after entering the environment gradually, and the interaction with metal ions in the aqueous environment has received extensive attention. However, there are few studies on Hg(Ⅱ), especially the effect of MPs on the release of Hg0(DEM) in water after entering the aqueous environment. In this study, four types of MPs (PP, PE, PET, PVC) were selected to study the adsorption and desorption behavior of Hg(Ⅱ) after photoaging and to explore the influence of MPs on the release of DEM in seawater under different lighting conditions. The results showed that the specific surface area, negative charges, and oxygen-containing functional group of MPs increased after aging. The adsorption capacity of aged MPs for Hg(Ⅱ) was significantly improved, which was consistent with the pseudo-first-order and pseudo-second-order model, indicating that the adsorption process was a chemical and physical adsorption. The fitting results of the in-particle diffusion model indicated that the adsorption was controlled by multiple steps. Hg(Ⅱ) was easier to desorb in the simulated gastric fluid environment. Because the aged MPs had the stronger binding force to Hg(Ⅱ), their desorption rate is lower than new MPs. Under visible light and UVA irradiation, MPs inhibited the release of Hg0. Under UVA, the mass of DEM produced in seawater with aged PE and PVC was higher than that of new PE and PVC. The aged PE and PVC could produce more ·O2-, which was conducive to the reduction of mercury. However, in UVB irradiation, the addition of MPs promoted the release of DEM, and ·O2- also played an important contribution in affecting the photochemical reaction of mercury. Therefore, the presence of aged MPs will significantly affect the water-air exchange of Hg in water. Compared with new MPs, aged MPs improved the contribution of free radicals in Hg transformation by releasing reactive oxygen species. This study extends the understanding of the effects of MPs on the geochemical cycle of Hg(Ⅱ) in seawater, better assesses the potential combined ecological risks of MPs and Hg(Ⅱ), and provides certain guidance for the pollution prevention and control of MPs.

Soybean-mediated suppression of BjaI/BjaR1 quorum sensing in Bradyrhizobium diazoefficiens impacts symbiotic nitrogen fixation.

The acyl-homoserine lactones (AHLs)-mediated LuxI/LuxR quorum sensing (QS) system orchestrates diverse bacterial behaviors in response to changes in population density. The role of the BjaI/BjaR1 QS system in Bradyrhizobium diazoefficiens USDA 110, which shares homology with LuxI/LuxR, remains elusive during symbiotic interaction with soybean. Here this genetic system in wild-type (WT) bacteria residing inside nodules exhibited significantly reduced activity compared to free-living cells, potentially attributed to soybean-mediated suppression. The deletion mutant strain ΔbjaR1 showed significantly enhanced nodulation induction and nitrogen fixation ability. Nevertheless, its ultimate symbiotic outcome (plant dry weight) in soybeans was compromised. Furthermore, comparative analysis of the transcriptome, proteome, and promoter activity revealed that the inactivation of BjaR1 systematically activated and inhibited genomic modules associated with nodulation and nitrogen metabolism. The former appeared to be linked to a significant decrease in the expression of NodD2, a key cell-density-dependent repressor of nodulation genes, while the latter conferred bacterial growth and nitrogen fixation insensitivity to environmental nitrogen. In addition, BjaR1 exerted a positive influence on the transcription of multiple genes involved in a so-called central intermediate metabolism within the nodule. In conclusion, our findings highlight the crucial role of the BjaI/BjaR1 QS circuit in positively regulating bacterial nitrogen metabolism and emphasize the significance of the soybean-mediated suppression of this genetic system for promoting efficient symbiotic nitrogen fixation by B. diazoefficiens.IMPORTANCEThe present study demonstrates, for the first time, that the BjaI/BjaR1 QS system of Bradyrhizobium diazoefficiens has a significant impact on its nodulation and nitrogen fixation capability in soybean by positively regulating NodD2 expression and bacterial nitrogen metabolism. Moreover, it provides novel insights into the importance of suppressing the activity of this QS circuit by the soybean host plant in establishing an efficient mutual relationship between the two symbiotic partners. This research expands our understanding of legumes' role in modulating symbiotic nitrogen fixation through rhizobial QS-mediated metabolic functioning, thereby deepening our comprehension of symbiotic coevolution theory. In addition, these findings may hold great promise for developing quorum quenching technology in agriculture.

Decoding the divalent cation effect on sulfidation of zero-valent iron: Phase evolution and FeSx assembly.

The decontamination ability of sulfidated zero-valent iron (S-ZVI) can be enhanced by the effective assembly of iron sulfides (FeSx) on neglected heterogeneous surfaces by liquid-phase precipitation. However, S-ZVI preparation with the usual pickling is detrimental to orderly interfacial assembly and leads to an imbalance between electron transfer optimization and electron storage. In this work, S-ZVI was prepared in solutions containing trace divalent cation, and it removed Cr(VI) up to 323.25 times higher than ZVI. This result is achieved by surface sites protonation of divalent cations regulating the phase evolution on the ZVI surface and inducing FeSx chemical assembly. Regulation of divalent cation and S(-II) content further promotes FeSx targeted assembly and reduces electron storage consumption as much as possible. The barrier for FeSx assembly is found to lie at the ZVI interface rather than in the deposition between FeSx. Chemical assembly at heterogeneous interfaces is a prerequisite for the ordered assembly of FeSx. In addition, S-ZVI prepared in simulated groundwater showed extensive preparation pH and universality for remediation scenarios. These findings provide new insights into the development of in-situ sulfidation mechanisms with particular implications for S-ZVI applied to soil and groundwater remediation by the regulation of heterogeneous interfacial assembly.

Comparison of three digestion methods for microplastic extraction from aquaculture feeds.

Microplastics (MPs) are ubiquitous pollutants found in aquaculture animals that may threaten human health through the food chain. However, there is a lack of effective methods for extracting MPs from aquaculture feeds containing complex components such as organic matter and fish bones. Therefore, in the present study, the extraction efficiency of three digestion methods using 30 % H2O2, Fenton reagent, and 30 % H2O2 + HNO3 for different particle sizes and types of MPs in aquaculture feeds was investigated and compared. The total digestion efficiency of the aquaculture feeds by 30 % H2O2 was 97.3 ± 0.1 %, while the recovery efficiency of MPs was 91.3 ± 1.1 % -103.1 ± 0.9 %. However, there was a large deviation in the extraction efficiency of MPs from aquaculture feeds by the Fenton reagent and 30 % H2O2 + HNO3. Notably, the surface morphology, particle size distribution, and oxidation degree of MPs hardly changed after 30 % H2O2 digestion. More importantly, the changes in the spectral features and carbonyl index of MPs after 30 % H2O2 digestion were smaller than those of the Fenton reagent and 30 % H2O2 + HNO3, which did not affect the identification of MPs. Overall, 30 % H2O2 was more efficient in extracting MPs from aquaculture feeds, and no significant effect on the characteristics of MPs was observed. This work provides novel insights into the effect of chemical pretreatment on the extraction of MPs in aquaculture feeds and provides an optimal protocol for the detection of MPs in aquaculture feeds.

Fungal community composition changes and reduced bacterial diversity drive improvements in the soil quality index during arable land restoration.

Arable land is facing the growing challenge of land degradation due to intensive use and this is beginning to affect global food security. However, active and passive restoration can improve soil characteristics and reshape microbial communities. Despite the increasing focus on changes in microbial communities during restoration, the mechanisms underlying how microbes drive the soil quality index (SQI) in arable land restoration remain unclear. In this study, we selected conventional farmland (CF, heavily intensified) and two restoration strategies (AR, artificial restoration; NR, natural restoration), with the same context (including soil texture, climate, etc.), and measured the microbial indicators over 2 years to investigate the mechanisms driving SQI improvement on restored arable land. The AR and NR treatments resulted in a 50% and 58% increase in SQI, respectively, compared to CF as soil nutrient levels increased, resulting in higher microbial biomasses and enzyme activities. Microbial abundance on the AR land was approximately two times greater than on the NR land due to the introduction of legumes. Bacterial diversity declined, while fungi developed in a more diverse direction under the restoration strategies. The AR and NR areas were mainly enriched with rhizobium (Microvirga, Bradyrhizobium), which contribute to healthy plant growth. The pathogenic fungi (Gibberella, Fusarium, Volutella) were more abundant in the CF area and the plant pathogen guild was about five times higher in the restored areas. Following arable land restoration, microbial life history strategies shifted from r-to K-strategists due to the higher proportion of recalcitrant SOC (DOC/SOC decreased by 18%-30%). The altered microbial community in the restored areas created new levels of functionality, with a 2.6%-4.3% decrease in bacterial energy metabolism (oxidative phosphorylation, C fixation, and N metabolism decreased by 7%, 4%, and 6%, respectively). Structural equation modelling suggested that restoration strategy affected SQI either directly by increasing total soil nutrient levels or indirectly by altering the microbial community and that fungal community composition and bacterial diversity made the largest contributions to SQI. These results provided new insights into soil quality improvement from a microbial perspective and can help guide future arable land restoration.

Performance and mechanism of SMX removal by an electrolysis-integrated ecological floating bed at low temperatures: A new perspective of plant activity, iron plaque, and microbial functions.

Improvements in plant activity and functional microbial communities are important to ensure the stability and efficiency of pollutant removal measures in cold regions. Although electrochemistry is known to accelerate pollutant degradation, cold stress acclimation of plants and the stability and activity of plant-microbial synergism remain poorly understood. The sulfamethoxazole (SMX) removal, iron plaque morphology, plant activity, microbial community, and function responses were investigated in an electrolysis-integrated ecological floating bed (EFB) at 6 ± 2 â„ƒ. Electrochemistry significantly improved SMX removal and plant activity. Dense and uniform iron plaque was found on root surfaces in L-E-Fe which improved the plant adaptability at low temperatures and provided more adsorption sites for bacteria. The microbial community structure was optimized and the key functional bacteria for SMX degradation (e.g., Actinobacteriota, Pseudomonas) were enriched. Electrochemistry improves the relative abundance of enzymes related to energy metabolism, thereby increasing energy responses to SMX and low temperatures. Notably, electrochemistry improved the expression of target genes (sadB and sadC, especially sadC) involved in SMX degradation. Electrochemistry enhances hydrogen bonding and electrostatic interactions between SMX and sadC, thereby enhancing SMX degradation and transformation. This study provides a deeper understanding of the electrochemical stability of antibiotic degradation at low temperatures.

The prolonged effect of film mulch and P application on lucerne forage yield in a semiarid environment.

Introduction: Limited water and soil phosphorus (P) availability often hampers lucerne productivity in semiarid regions. Plastic film mulch and P application typically enhance young lucerne (2-3 years) productivity by increasing soil water use and P availability. However, the prolonged impact of film mulch and P application on lucerne productivity as the stand ages remains unclear. Methods: This study conducted a 9-year field experiment on the semiarid Loess Plateau to investigate how film mulch and P application affect lucerne forage yield, soil water content, and soil fertility. The field experiment used a split-plot design with randomized blocks, in which the whole plots were with (M1) and without plastic film mulch (M0), and the split plots were four P rates (0 (P0), 9.7 (P1), 19.2 (P2), and 28.8 (P3) kg P ha-1). Results and discussion: The M1 treatment produced significantly higher lucerne forage yields than the M0 treatment during the first five years, but the yield-increasing effect of film mulch gradually diminished over time, with no effect in Years 6-8, and lower yields than the M0 treatment in Year 9. Phosphorus fertilization significantly increased forage yield after Year 3 in the M0 treatment, but only in Years 3-5 in the M1 treatment. In Years 2-5, film mulch significantly increased soil organic carbon, total nitrogen (N), inorganic N, and microbial biomass carbon in P0, P1, and P2 but not in P3. However, in Years 7-9, film mulch significantly decreased soil available potassium (K), organic carbon mineralization, lucerne density, and shoot K concentration, but did not reduce soil N and P availability at any level P of application. Moreover, plastic film mulch significantly increased the soil water content at 0-300 cm deep from Year 7 onwards. In conclusion, film mulch ceased to enhance lucerne production beyond year 6, which could not be attributed to soil water content, N or P availability but was partially associated with reduced soil K availability. Consequently, future research should focus on soil K availability, and K addition should be considered after five years in lucerne pastures mulched with plastic film in semiarid areas.

[Photodegradation of Plastic Blends in Seawater and Its Risk to the Marine Environment].

The production and use of plastic blends have been gradually increasing owing to their versatility and low cost. However, the photodegradation of plastic blends in seawater and the potential risk to the marine environment are still not well understood. In this study, plastic blends including polypropylene/thermoplastic starch blends(PP/TPS) and polylactic acid/poly(butylene adipate-co-terephthalate)/thermoplastic starch blends(PLA/PBAT/TPS) were investigated. The corresponding neat polymers, namely polypropylene(PP) and polylactic acid(PLA), were set as control groups. We investigated the formation of MPs and the changes in the physicochemical properties of plastic blends after photodegradation in seawater. The size distribution of MPs indicated that PP/TPS and PLA/PBAT/TPS were more likely to produce small-sized particles after photodegradation than PP and PLA owing to their poorer mechanical properties and lower resistance to UV irradiation. Noticeable surface morphology alterations, including cracks and wrinkles, were observed for plastic blends following photodegradation, whereas PP and PLA were relatively resistant. After photodegradation, the ATR-FTIR spectrum of PP/TPS and PLA/PBAT/TPS showed a significant decrease in the characteristic bands of thermoplastic starch(TPS), indicating the degradation of their starch fractions. The C 1s spectra demonstrated that aged plastic blends contained fewer -OH groups than the pristine MPs did, further confirming the photodegradation of TPS. These results indicate that PP/TPS and PLA/PBAT/TPS had a higher degree of photodegradation than PP and PLA and thereby generated more small-sized MPs. In summary, plastic blends may pose a higher risk to the marine environment than neat polymers, and caution should be taken in the production and use of plastic blends.

Seasonal resource selection of free-ranging Zhongwei goats in the semi-arid grassland.

Goats rarely move and forage randomly. They tend to move in ways generally influenced by biotic and abiotic factors, respectively. However, few studies have explored the foraging behaviour of goats in the absence of predation and human disturbance. Based on step selection function modelling framework, Normalised Difference Vegetation Index, vegetation surveys, and Global Positioning System tracking of 124 free-ranging domestic adult male Zhongwei goats over one year (2016-2017) were used to assess how biotic and abiotic environmental factors affected their spatiotemporal distribution, and developed a conceptual model to represent the goats' trade-off between forage quantity and preference at different seasons, in the semi-arid grassland of Loess Plateau of 1 178 hectare. The results showed that spatial distributions of goats responded to spatiotemporal variation of biotic factors rather than abiotic factors of elevation, slope and solar radiation, which indicated that biotic factors were of priority to abiotic factors in the foraging process for the goats. According to the season changing, the goats positively used areas with higher forage quantity in the spring and winter, areas of higher forage quantity and preferred species in summer, and areas of abundance of preferred species in autumn. We developed a model to describe the phenomenon that the goats selected areas with higher preferred species only when the forage quantity was plentiful, otherwise they selected areas with higher forage quantity. Better understanding of the patterns and drivers of spatiotemporal distribution of the goats can improve our ability to predict foraging behaviour of livestock in heterogeneous environment and lead to better management practices and policies for the sustainability of these semi-arid landscapes and associated ecosystem services.

First insights into 6PPD-quinone formation from 6PPD photodegradation in water environment.

p-Phenylenediamines (PPDs), an important type of rubber antioxidants, have received little study on their environmental fate, particularly for their vital photodegradation process in water environment. Accordingly, N-(1,3-dimethylbutyl)-N'-phenyl-1,4-phenylenediamine (6PPD), as a representative of PPDs, was investigated experimentally and theoretically for its photodegradation in water. Rapid photodegradation occurred when 6PPD was exposed to illumination especially UV region irradiation. Under acidic conditions, the photodegradation of 6PPD accelerated mainly due to the increased absorption of long wavelength irradiation by ionized 6PPD. Nine photodegradation products (e.g., 6PPD-quinone (6PPDQ)) of 6PPD were identified by an ultra-performance liquid chromatography QTOF mass spectrometry. Molar yields of photoproducts such as 6PPDQ, aniline, 4-aminodiphenylamine, and 4-hydroxydiphenylamine were 0.03 ± 0.00, 0.10 ± 0.01, 0.03 ± 0.02, and 0.08 ± 0.01, respectively. Mechanisms involved in 6PPD photodegradation include photoexcitation, direct photolysis, self-sensitized photodegradation, and 1O2 oxidation, as demonstrated by electron paramagnetic resonance (EPR) analysis, scavenging experiments, and the time-dependent density functional theory (TD-DFT). Notably, the toxicity of the reaction solution formed during the photodegradation of 6PPD was increased by the formation of highly toxic products (e.g., 6PPDQ). This study provides the first explanation for photodegradation mechanisms of 6PPD and confirms the pathway of 6PPDQ produced by the photoreaction in water environment.

Plant biomass mediates the decomposition of polythene film-sourced pollutants in soil through plastisphere bacteria island effect.

The polyethylene (PE) film mulching as a water conservation technology has been widely used in dryland agriculture, yet the long-term mulching has led to increasing accumulation of secondary pollutants in soils. The decomposition of PE film-sourced pollutants is directly associated with the enrichment of specific bacterial communities. We therefore hypothesized that plant biomass may act as an organic media to mediate the pollutant decomposition via reshaping bacterial communities. To validate this hypothesis, plant biomass (dried maize straw and living clover) was embedded at the underlying surface of PE film, to track the changes in the composition and function of bacterial communities in maize field across two years. The results indicated that both dry crop straw and alive clover massively promoted the α-diversity and abundance of dominant bacteria at plastisphere, relative to bulk soil. Bacterial communities tended to be clustered at plastisphere, forming the bacteria islands to enrich pollutant-degrading bacteria, such as Sphingobacterium, Arthrobacter and Paracoccus. As such, plastisphere bacteria islands substantially enhanced the degradation potential of chloroalkene and benzoate (p < 0.05). Simultaneously, bacterial network became stabilized and congregated at plastisphere, and markedly improved the abundance of plastisphere module hubs and connectors bacteria via stochastic process. Particularly, bacterial community composition and plastic film-sourced pollutants metabolism were evidently affected by soil pH, carbon and nitrogen sources that were mainly derived from the embedded biomass. To sum up, plant biomass embedding as a nature-based strategy (NbS) can positively mediate the decomposition of plastic-sourced pollutants through plastisphere bacteria island effects.

Occurrence of microplastics in three types of household cleaning products and their estimated emissions into the aquatic environment.

Microplastics (MPs) in household cleaning products are a significant source of primary MPs. However, their presence in these products remain largely unknown. In this study, three types of common household cleaning products (laundry detergents, toilet bowl cleaners, and dishwashing detergents) were examined to assess the presence of MPs. The potential global emissions of MPs into aquatic environments resulting from the use of these products were estimated using statistics on global wastewater treatment plants (WWTPs) and household cleaning product markets. The average abundance of MPs in household cleaning products was 564.97 ± 327.83 n·kg-1, with toilet bowl cleaners having a significantly higher abundance than the other two products. The most commonly detected polymers in these products were polyamide (PA), silicone, polyurethane (PU), acrylate copolymer (ACR), polyethylene (PE), and polyethylene terephthalate (PET), while the size of the MPs ranged from 21.34 to 442.97 µm, with 81.52 % being <50 µm and 87.32 % being fragment-shaped. The estimated annual MP emissions from these three types of household cleaning products were 3.88 × 1013 ± 1.35 × 1013, with toilet bowl cleaners accounting for 56.44 % of the total emissions. MPs directly released without treatment in WWTPs (2.46 × 1013 n year-1) accounted for 63.40 % of the total emissions, highlighting the importance of increasing the treated rate of wastewater to reduce MP emissions. Sensitivity tests indicated that increasing the MP removal rates of secondary and tertiary WWTPs could also effectively reduce MP emissions. Moreover, gross and per capita MP emissions in 149 countries showed significant differences, which could be attributed to population, market size, demand for household cleaning products, and the level of MP removal among different countries. The findings of this study provide important insights into controlling MP contamination in household cleaning products.

Fabrication and optimization of paper chips from calcinated Fe-MOFs for rapid and in situ visual detection of tetracyclines in water environments.

Antibiotics such as tetracyclines (TCs) have become a major threat to ecosystem safety and human health, as their abuse has caused the occurrence and proliferation of antibiotic-resistant bacteria and genes. Currently, there is still a lack of convenient in situ methods for the detection and monitoring of TC pollution in actual water systems. This research reports a paper chip based on the complexation of iron-based metal organic frameworks (Fe-MOFs) and TCs for rapid and in situ visual detection of representative oxytetracycline (OTC) pollution in water environments. The optimized complexation sample NH2-MIL-101(Fe)- 350 obtained by calcination at 350 °C exhibited the highest catalytic activity and was then used for paper chip fabrication by printing and surface modification. Notably, the paper chip demonstrated a detection limit as low as 17.11 nmol L-1 and good practicability in reclaimed water, aquaculture wastewater, and surface water systems, with OTC recovery rates of 90.6-111.4%. More importantly, the presence of dissolved oxygen (9.13-12.7 mg L-1), chemical oxygen demand (0.52-12.1 mg L-1), humic acid (< 10 mg L-1), Ca2+, Cl-, and HPO42- (< 0.5 mol L-1) had negligible interference on the detection of TCs by the paper chip. Therefore, this work has developed a promising method for rapid and in situ visual monitoring of TC pollution in actual water environments.

The impact of crop residue return on the food-carbon-water-energy nexus in a rice-wheat rotation system under climate warming.

Rice-wheat rotation (RWR) is one of the major cropping systems in China and plays a crucial role in the country's food security. With the promotion of "burn ban" and "straw return" policies, the "straw return + rice-wheat crop rotation system" has been developed in China's RWR area. However, the effect of promotion of straw return on production and ecological benefits of RWR areas is unclear. In this study, the main planting zones of RWR were examined, and ecological footprints and scenario simulation were applied to explore the effect of straw return on the food-carbon-water-energy nexus under conditions of a warming world. The results indicate that with rising temperatures and the promotion of straw return policies, the study area was in a "carbon sink" state during 2000-2019. The study area's total yield climbed by 48 % and the carbon (CF), water (WF) and energy (EF) footprints decreased by 163 %, 20 % and 11 %, respectively. Compared to 2000-2009, the temperature increase for 2010-2019 was negatively correlated with the increase in CF and WF and positively correlated with the increase of yield and EF. A 16 % reduction in chemical fertilizers, increasing the straw return rate to 80 % and utilizing tillage techniques such as furrow-buried straw return would contribute to sustainable agriculture in the RWR area under a projection of 1.5 °C increase in air temperature. The promotion of straw return has contributed to improved production and the maintenance and reduction of CF, WF, and EF in the RWR, but further optimization measures are required to reduce the footprint of agriculture in a warmer world.

Research review on the pollution of antibiotic resistance genes in livestock and poultry farming environments.

Increasingly serious pollution of antibiotic resistance genes (ARGs) caused by the abuse of antibiotics in livestock and poultry industry has raised worldwide concerns. ARGs could spread among various farming environmental media through adsorption, desorption, migration, and also could transfer into human gut microbiome by hori-zontal gene transfer (HGT), posing potential threats to public health. However, the comprehensive review on the pollution patterns, environmental behaviors, and control techniques of ARGs in livestock and poultry environments in view of One Health is still inadequate, resulting in the difficulties in effectively assessing ARGs transmission risk and developing the efficient control strategies. Here, we analyzed the pollution characteristics of typical ARGs in various countries, regions, livestock species, and environmental media, reviewed the critical environmental fate and influencing factors, control strategies, and the shortcomings of current researches about ARGs in the livestock and poultry farming industry combined with One Health philosophy. In particular, we addressed the importance and urgency of identifying the distribution characteristics and environmental process mechanisms of ARGs, and developing green and efficient ARG control means in livestock farming environments. We further proposed gaps and prospects for the future research. It would provide theoretical basis for the research on health risk assessment and technology exploitation of alleviating ARG pollution in livestock farming environment.

Hormetic Effect of Pyroligneous Acids on Conjugative Transfer of Plasmid-mediated Multi-antibiotic Resistance Genes within Bacterial Genus.

Spread of antibiotic resistance genes (ARGs) by conjugation poses great challenges to public health. Application of pyroligneous acids (PA) as soil amendments has been evidenced as a practical strategy to remediate pollution of ARGs in soils. However, little is known about PA effects on horizontal gene transfer (HGT) of ARGs by conjugation. This study investigated the effects of a woody waste-derived PA prepared at 450°C and its three distillation components (F1, F2, and F3) at different temperatures (98, 130, and 220°C) on conjugative transfer of plasmid RP4 within Escherichia coli. PA at relatively high amount (40-100 µL) in a 30-mL mating system inhibited conjugation by 74-85%, following an order of PA > F3 ≈ F2 ≈ F1, proving the hypothesis that PA amendments may mitigate soil ARG pollution by inhibiting HGT. The bacteriostasis caused by antibacterial components of PA, including acids, phenols, and alcohols, as well as its acidity (pH 2.81) contributed to the inhibited conjugation. However, a relatively low amount (10-20 µL) of PA in the same mating system enhanced ARG transfer by 26-47%, following an order of PA > F3 ≈ F2 > F1. The opposite effect at low amount is mainly attributed to the increased intracellular reactive oxygen species production, enhanced cell membrane permeability, increased extracellular polymeric substance contents, and reduced cell surface charge. Our findings highlight the hormesis (low-amount promotion and high-amount inhibition) of PA amendments on ARG conjugation and provide evidence for selecting an appropriate amount of PA amendment to control the dissemination of soil ARGs. Moreover, the promoted conjugation also triggers questions regarding the potential risks of soil amendments (e.g., PA) in the spread of ARGs via HGT.

Insight into pharmaceutical and personal care products removal using constructed wetlands: A comprehensive review.

Pharmaceutical and personal care products (PPCPs) were regarded as emerging environmental pollutants due to their ubiquitous appearance and high environmental risks. The wastewater treatment plants (WWTPs) became the hub of PPCPs receiving major sources of PPCPs used by humans. Increasing concern has been focused on promoting cost-effective ways to eliminate PPCPs within WWTPs for blocking their route into the environment through effluent discharging. Among all advanced technologies, constructed wetlands (CWs) with a combination of plants, substrates, and microbes attracted attention due to their cost-effectiveness and easier maintenance during long-term operation. This study offers baseline data for risk control and future treatment by discussing the extent and dispersion of PPCPs in surface waters over the past ten years and identifying the mechanisms of PPCPs removal in CWs based on the up-to-present research, with a special focus on the contribution of sediments, vegetation, and the interactions of microorganisms. The significant role of wetland plants in the removal of PPCPs was detailed discussed in identifying the contribution of direct uptake, adsorption, phytovolatilization, and biodegradation. Meanwhile, the correlation between the physical-chemical characteristics of PPCPs, the configuration operation of wetlands, as well as the environmental conditions with PPCP removal were also further estimated. Finally, the critical issues and knowledge gaps before the real application were addressed followed by promoted future works, which are expected to provide a comprehensive foundation for study on PPCPs elimination utilizing CWs and drive to achieve large-scale applications to treat PPCPs-contaminated surface waters.

Improving the Quality of Reclaimed Water via Applying Spirulina platensis to Eliminate Residual Nitrate.

The application of reclaimed water has been recognized as the key approach for alleviating water scarcity, while its low quality, such as high nitrogen content, still makes people worry about the corresponding ecological risk. Herein, we investigated the feasibility of removing residual nitrate from reclaimed water by applying Spirulina platensis. It is found that 15 mg/L total nitrogen could be decreased to 1.8 mg/L in 5 days, equaling 88.1 % removal efficiency under the optimized conditions. The deficient phosphorus at 0.5-1.0 mg/L was rapidly eliminated but was already sufficient to support nitrate removal by S. platensis. The produced ammonia is generally below 0.2 mg/L, which is much lower than the standard limit of 5 mg/L. In such a nutrient deficiency condition, S. platensis could maintain biomass growth well via photosynthesis. The variation of pigments, including chlorophyll a and carotenoids, suggested a certain degree of influences of illumination intensity and phosphorus starvation on microalgae. The background cations Cu2+ and Zn2+ exhibited significant inhibition on biomass growth and nitrate removal; thus, more attention needs to be paid to the further application of microalgae in reclaimed water. Our results demonstrated that cultivation of S. platensis should be a very promising solution to improve the quality of reclaimed water by efficiently removing nitrate and producing biomass.

The different toxicological effects and removal efficiencies of norfloxacin and sulfadiazine in culturing Arthrospira (Spirulina) platensis.

Norfloxacin (NFX) and sulfadiazine (SDZ) are two widely used antibiotics belonging to fluoroquinolone and sulfonamide groups, respectively, and have become the commonly detected micropollutants in aquatic environments. However, only few works have been conducted to investigate the highly probable inhibition of these antibiotic pollutants to Arthrospira platensis, which is an important species of cyanobacteria that is one of primary producers in aquatic ecosystems and should be remarkably sensitive to environmental pollutants due to its prokaryotic characteristics. Hence, the toxicological effects and removal efficiencies of NFX and SDZ in culturing A. platensis were studied by analyzing the biomass growth, photosynthetic pigments, primary biocomponents, and antibiotics concentration. The corresponding variations of these characteristics showed the higher sensitivity of A. platensis to NFX than to SDZ, indicating the specifically targeted effect of NFX on A. platensis, which could be confirmed in silico by the higher binding affinity of NFX with the critical enzyme. The obtained results illustrated the roles of NFX and SDZ on the growth of A. platensis, thus providing the great support in employing A. platensis to reduce hazards from contaminated water and recover biomass resources.