California's methane super-emitters.

Methane is a powerful greenhouse gas and is targeted for emissions mitigation by the US state of California and other jurisdictions worldwide1,2. Unique opportunities for mitigation are presented by point-source emitters-surface features or infrastructure components that are typically less than 10 metres in diameter and emit plumes of highly concentrated methane3. However, data on point-source emissions are sparse and typically lack sufficient spatial and temporal resolution to guide their mitigation and to accurately assess their magnitude4. Here we survey more than 272,000 infrastructure elements in California using an airborne imaging spectrometer that can rapidly map methane plumes5-7. We conduct five campaigns over several months from 2016 to 2018, spanning the oil and gas, manure-management and waste-management sectors, resulting in the detection, geolocation and quantification of emissions from 564 strong methane point sources. Our remote sensing approach enables the rapid and repeated assessment of large areas at high spatial resolution for a poorly characterized population of methane emitters that often appear intermittently and stochastically. We estimate net methane point-source emissions in California to be 0.618 teragrams per year (95 per cent confidence interval 0.523-0.725), equivalent to 34-46 per cent of the state's methane inventory8 for 2016. Methane 'super-emitter' activity occurs in every sector surveyed, with 10 per cent of point sources contributing roughly 60 per cent of point-source emissions-consistent with a study of the US Four Corners region that had a different sectoral mix9. The largest methane emitters in California are a subset of landfills, which exhibit persistent anomalous activity. Methane point-source emissions in California are dominated by landfills (41 per cent), followed by dairies (26 per cent) and the oil and gas sector (26 per cent). Our data have enabled the identification of the 0.2 per cent of California's infrastructure that is responsible for these emissions. Sharing these data with collaborating infrastructure operators has led to the mitigation of anomalous methane-emission activity10.

Control of odor emissions from livestock farms: A review.

Odor emission seriously affects human and animal health, and the ecological environment. Nevertheless, a systematic summary regarding the control technology for odor emissions in livestock breeding is currently lacking. This paper summarizes odor control technology, highlighting its applicability, advantages, and limitations, which can be used to evaluate and identify the most appropriate methods in livestock production management. Odor control technologies are divided into four categories: dietary manipulation (low-crude protein diet and enzyme additives in feed), in-housing management (separation of urine from feces, adsorbents used as litter additive, and indoor environment/manure surface spraying agent), manure management (semi-permeable membrane-covered, reactor composting, slurry cover, and slurry acidification), and end-of-pipe measures for air treatment (wet scrubbing of the exhaust air from animal houses and biofiltration of the exhaust air from animal houses or composting). Findings of this paper provide a theoretical basis for the application of odor control technology in livestock farms.

Green manure incorporation accelerates enzyme activity, plant growth, and changes in the fungal community of soil.

Green manure can sustain agricultural production, preserve biodiversity, and mitigate soil degradation caused by long-term application of chemical fertilizers. Moreover, the application of green manure can improve soil health through increased soil biological activities. Nevertheless, little attention has been paid to the effects of leguminous and non-leguminous plants on phosphorus- and carbon-related enzyme activities and fungal community composition in soil. In this study, a pot experiment was carried out to elucidate the effects of two green manures on plant growth promoting potential, phosphorus- and carbon-related enzyme activities, and soil fungal community composition. Two green manure treatments (Brassica juncea and hairy vetch), poultry compost and control (no amendment) were applied and soil samples were collected after incorporation of green manure and after plant harvest. The results revealed that plant growth with hairy vetch was significantly higher than that with B. juncea and poultry compost, and soil enzyme activities were markedly higher with hairy vetch than with B. juncea. Both green manure amendments altered the soil fungal community composition. It is possible that the incorporation of green manure into soil and their mineralization and decomposition were controlled by the carbon: nitrogen ratio of the manures and that these manures were easily degradable by soil fungi. In particular, the incorporation of leguminous (hairy vetch) green manure with a low carbon: nitrogen ratio resulted in better plant growth through fast mineralization. Our findings suggest that green manure incorporation is an effective practice and provides substantial benefits to the soil-plant system.

Characteristics and Complete Genome Analysis of Bacillus asahii OM18, a Bacterium in Relation to Soil Fertility in Alkaline Soils Under Long-Term Organic Manure Amendment.

Bacillus asahii strain OM18, a bacterium in relation to soil fertility, was isolated from alkaline soils under long-term organic manure application in the North China Plain. B. asahii species play a pivotal role in the promotion of both crop yield and soil fertility via accelerating carbon and phosphorus cycling. However, little is known about the characteristics of B. asahii and its underlying molecular mechanism involved in soil nutrient cycling as well as its potential in promoting crop growth. To this end, we report the characteristics and complete genome analysis of strain OM18, which is relevant to promoting plant growth in phosphorus-deficient alkaline soils. Our results provide a glimpse into the metabolic function of B. asahii OM18.

Effect of Different Proportions of Three Microbial Agents on Ammonia Mitigation during the Composting of Layer Manure.

Odor emissions represent one of the important issues of aerobic composting. The addition of microbial agents to compost is an important method for solving this problem, but this process is often unstable when a single microbial agent is added to the compost. Therefore, in this study, five treatments comprising different proportions of Bacillus stearothermophilus, Candida utilis, and Bacillus subtilis were tested to determine the best combination of the three microbial agents for ammonia reduction, as follows: control group (CK), 2:1:1 (A), 1:1:2 (B), 1:2:1 (C), and 1:1:1 (D). Compared with the CK group, the A, B, C, and D groups reduced ammonia emissions by 17.02, 9.68, 53.11, and 46.23%, respectively. The total ammonia emissions were significantly lower in C and D than in CK (p < 0.05). These two treatment groups had significantly increased nitrate nitrogen concentrations and decreased pH values and ammonium nitrogen concentrations (p < 0.05). Throughout the composting process, the total bacterial number was significantly higher in C and D than in CK (p < 0.05). Therefore, it is likely that B. stearothermophilus, C. utilis, and B. subtilis compounded from 1:2:1 (C) to 1:1:1 (D) reduced the ammonia emissions due to (1) a reduction in the pH and (2) the promotion of the growth of ammonia-oxidizing bacteria and the conversion of ammonium nitrogen to nitrate nitrogen. This study provides a theoretical basis and technical support for the odor problem of layer manure compost and promotes the development of composting technology.

'WE CAN'T GET WORMS FROM COW DUNG': REPORTED KNOWLEDGE OF PARASITISM AMONG PASTORALIST YOUTH ATTENDING SECONDARY SCHOOL IN THE NGORONGORO CONSERVATION AREA, TANZANIA.

Records at the Endulen Hospital in the Ngorongoro Conservation Area (NCA), Tanzania, reveal that soil-transmitted helminth infections and protozoa are consistently in the top ten diagnoses for Maasai pastoralists, indicating a significant public health concern. Nevertheless, Maasai pastoralist adaptations to life in close proximity to livestock and to unreliable access to water raise important questions about experiences of, and resiliency to, parasitic infections. Though these infections are particularly prevalent among youth in low- and middle-income countries (LMIC), a focus on resiliency highlights local capacity to recover from and prevent illness. For instance, how is human parasitism perceived and experienced among communities displaying behaviours that studies have associated with transmission of diarrhoeal diseases, such as open defecation? Among these communities, how is parasitism seen to impact the health and development of children? And, what resources are available to endure or mitigate this heavy disease burden among affected communities? This study draws on formative research carried out in May 2014 in anticipation of an innovative school-based and youth-driven water, sanitation and hygiene education intervention rolled out in two boarding schools in the NCA in subsequent months. The initiative is grounded in a One Health approach to health promotion, drawing on partnerships in medicine, public health and veterinary medicine to appreciate the unique interactions between humans, animals and the environment that shape well-being among pastoralist communities. Qualitative data generated through group discussions with secondary school youth (n=60), Maasai teachers (n=6) and a women's group (n=8) in the NCA convey existing knowledge of the prevalence, prevention and treatment of human parasitism. An underlying principle of the larger initiative is to engage youth as creative agents of change in developing and sustaining locally relevant health promotion strategies. Findings highlight practical knowledge around certain 'neglected tropical diseases', namely helminths, among pastoralist communities in the NCA, in turn feeding into the development of the science fair and related interventions.

Building a strategy for soil protection at local and regional scale--the case of agricultural wastes landspreading.

Agricultural wastes (AW) are produced in huge quantities worldwide and may cause detrimental effects on environmental quality, affecting soil, water, and air quality. Given the growing soil degradation worldwide, the need for more food of good quality and therefore the intensified agriculture, it is important to develop recycling plans even for those types of treated AW (e.g., composts) that are not considered hazardous. Two strategic approaches for safe and sustainable landspreading of organic wastes are proposed, depending on wastes properties and hazard potential, i.e., an approach appropriate for traditionally used wastes (manures and composts) and another approach for wastes that are potentially hazardous or hazardous and should only be reused under specific restrictions. Both approaches foresee concrete steps, require close cooperation between farmers and local/regional authorities, and are appropriate to ensure environmental sustainability at AW recycling or disposal areas. Desktop and web application tools are also presented that are anticipated to assist authorities in implementing their monitoring strategies.

Greenhouse gas emissions from dairy manure management: a review of field-based studies.

Livestock manure management accounts for almost 10% of greenhouse gas emissions from agriculture globally, and contributes an equal proportion to the US methane emission inventory. Current emissions inventories use emissions factors determined from small-scale laboratory experiments that have not been compared to field-scale measurements. We compiled published data on field-scale measurements of greenhouse gas emissions from working and research dairies and compared these to rates predicted by the IPCC Tier 2 modeling approach. Anaerobic lagoons were the largest source of methane (368 ± 193 kg CH4 hd(-1) yr(-1)), more than three times that from enteric fermentation (~120 kg CH4 hd(-1) yr(-1)). Corrals and solid manure piles were large sources of nitrous oxide (1.5 ± 0.8 and 1.1 ± 0.7 kg N2O hd(-1) yr(-1), respectively). Nitrous oxide emissions from anaerobic lagoons (0.9 ± 0.5 kg N2O hd(-1) yr(-1)) and barns (10 ± 6 kg N2O hd(-1) yr(-1)) were unexpectedly large. Modeled methane emissions underestimated field measurement means for most manure management practices. Modeled nitrous oxide emissions underestimated field measurement means for anaerobic lagoons and manure piles, but overestimated emissions from slurry storage. Revised emissions factors nearly doubled slurry CH4 emissions for Europe and increased N2O emissions from solid piles and lagoons in the United States by an order of magnitude. Our results suggest that current greenhouse gas emission factors generally underestimate emissions from dairy manure and highlight liquid manure systems as promising target areas for greenhouse gas mitigation.

Mitigation of ammonia, nitrous oxide and methane emissions from manure management chains: a meta-analysis and integrated assessment.

Livestock manure contributes considerably to global emissions of ammonia (NH3 ) and greenhouse gases (GHG), especially methane (CH4 ) and nitrous oxide (N2 O). Various measures have been developed to mitigate these emissions, but most of these focus on one specific gas and/or emission source. Here, we present a meta-analysis and integrated assessment of the effects of mitigation measures on NH3 , CH4 and (direct and indirect) N2 O emissions from the whole manure management chain. We analysed the effects of mitigation technologies on NH3 , CH4 and N2 O emissions from individual sources statistically using results of 126 published studies. Whole-chain effects on NH3 and GHG emissions were assessed through scenario analysis. Significant NH3 reduction efficiencies were observed for (i) housing via lowering the dietary crude protein (CP) content (24-65%, compared to the reference situation), for (ii) external slurry storages via acidification (83%) and covers of straw (78%) or artificial films (98%), for (iii) solid manure storages via compaction and covering (61%, compared to composting), and for (iv) manure application through band spreading (55%, compared to surface application), incorporation (70%) and injection (80%). Acidification decreased CH4 emissions from stored slurry by 87%. Significant increases in N2 O emissions were found for straw-covered slurry storages (by two orders of magnitude) and manure injection (by 26-199%). These side-effects of straw covers and slurry injection on N2 O emission were relatively small when considering the total GHG emissions from the manure chain. Lowering the CP content of feed and acidifying slurry are strategies that consistently reduce NH3 and GHG emissions in the whole chain. Other strategies may reduce emissions of a specific gas or emissions source, by which there is a risk of unwanted trade-offs in the manure management chain. Proper farm-scale combinations of mitigation measures are important to minimize impacts of livestock production on global emissions of NH3 and GHG.

Influence of soil pH in vegetative filter strips for reducing soluble nutrient transport.

Low efficacy of vegetative filter strips (VFS) in reducing soluble nutrients has been reported in research articles. Solubility of phosphorus and nitrogen compounds is largely affected by pH of soil. Changing soil pH may result in a decrease in soluble nutrient transportation through VFS. This study was conducted to evaluate the effect of pH levels of VFS soil on soluble nutrient transport reduction from manure-borne runoff. Soil (loamy sand texture; bulk density 1.3 g cm-3) was treated with calcium carbonate to change pH at different pH treatment levels (5.5-6.5, 6.5-7.5, and 7.5-8.5), soil was packed into galvanized metal boxes, and tall fescue grasses were established in the boxes to simulate VFS. Boxes were placed in an open environment, tilted to a 3.0% slope, and 44.0 L manure-amended water was applied through the VFS by a pump at a rate of 1.45 L min-1. Water samples were collected at the inlet and outlet as well as from the leachate. Samples were analysed for ortho-phosphorus, ammonium nitrogen, nitrate nitrogen, and potassium. Highest transport reductions in ortho-phosphorus (42.4%) and potassium (20.5%) were observed at pH range 7.5-8.5. Ammonium nitrogen transport reduction was the highest at pH level of 6.5-7.5 and was 26.1%. Surface transport reduction in nitrate nitrogen was 100%, but leachate had the highest concentration of nitrate nitrogen. Mass transport reduction also suggested that higher pH in the VFS soil are effective in reducing some soluble nutrients transport.

Impact of environmental policies on the adoption of manure management practices in the Chesapeake Bay watershed.

Pollution in the Chesapeake Bay is a problem and has been a focus of federal and state initiatives to reduce nutrient pollution from agriculture and other sources since 1983. In 2010 EPA established a TMDL for the watershed. Producers may voluntarily respond to intense and focused policy scrutiny by adopting best management practices. A detailed analysis of water quality best management practices by animal feeding operations inside and outside the watershed yield insight into this relationship. Our findings support the hypothesis that farmers will adopt water quality measures if links are made clear and there is an expectation of future regulations.

Maleic anhydride promotes humus formation via inducing functional enzymes response in composting.

The purpose of this paper was to explore the promotion of maleic anhydride on the polymerization of precursors into humus in composting, and analyze the changes of key functional enzymes. The results showed that the content of humus in the treatment group added maleic anhydride (MAH) was higher than that in the control check (CK). The decrease rate of humus precursor concentration of MAH was also higher than that of CK. In MAH, the activities of laccase and tyrosinase were improved, thus enhanced the catalytic conversion of humus precursors. The analysis of bacterial community showed that maleic anhydride optimized the community structure of humification functional enzymes producing bacteria, with the most obvious increase of Firmicutes. In conclusion, this study provided theoretical supports for the introduction of maleic anhydride into the compost system to promote the polymerization of precursors to form humus.

Improving the humification by additives during composting: A review.

Humic substances (HSs) are key indicators of compost maturity and are important for the composting process. The application of additives is generally considered to be an efficient and easy-to-master strategy to promote the humification of composting and quickly caught the interest of researchers. This review summarizes the recent literature on humification promotion by additives in the composting process. Firstly, the organic, inorganic, biological, and compound additives are introduced emphatically, and the effects and mechanisms of various additives on composting humification are systematically discussed. Inorganic, organic, biological, and compound additives can promote 5.58-82.19%, 30.61-50.92%, 2.3-40%, and 28.09-104.51% of humification during composting, respectively. Subsequently, the advantages and disadvantages of various additives in promoting composting humification are discussed and indicated that compound additives are the most promising method in promoting composting humification. Finally, future research on humification promotion is also proposed such as long-term stability, environmental impact, and economic feasibility of additive in the large-scale application of composting. It is aiming to provide a reference for future research and the application of additives in composting.

Effects of different planting distances and fertilizer use on the remediation of farmland contaminated with Cd by intercropping Cucurbita moschata and Amaranthus hypochondriacus L.

Selecting suitable agronomic measures can strengthen the application of intercropping in the remediation of cadmium (Cd)-contaminated soil. In this study, the effects of different planting densities and fertilizer applications on the crop growth and Cd absorption of a pumpkin (Cucurbita moschata)-Amaranthus hypochondriacus L. intercropping system was determined. The goal was to provide enhanced means and a scientific basis for the promotion and application of this intercropping system. The Cd content of pumpkin in different planting systems was lower than the national food safety standard (0.05 mg kg-1). In the IN-1 (4 pumpkin plants intercropped with 200 A. hypochondriacus plants) and IN-2 (4 pumpkin plants intercropped with 400 A. hypochondriacus plants) intercropping systems, the bioconcentration amount (BCA) per plant of Cd in A. hypochondriacus increased by 32.43% and 25.25%, respectively, compared with that of the monocropping system (P < 0.05). The IN-2 system had the highest equivalent ratio of heavy metal removal (3.08), indicating that this model had a substantial advantage for removing Cd. The land equivalent ratio of IN-1 (2.89) and IN-2 (2.60) was significantly higher than that of other intercropping systems, indicating that these two models had obvious yield advantages. In our study, chicken manure was the best at promoting the growth and yield of the two plants and sludge treatment significantly enhance Cd absorption of A. hypochondriacus. In general, intercropping four pumpkin plants with 400 A. hypochondriacus plants and applying chicken manure fertilizer can strengthen the application of this intercropping system in Cd-contaminated soil.

Investigation of biochar amendments on odor reduction and their characteristics during food waste co-composting.

The odor emission such as ammonia (NH3) and hydrogen sulfide (H2S) during the composting process is a severe problem that adversely affects the environment and human health. Therefore, this study aimed to (1) evaluate the variation of physicochemical characteristics during the co-composting of food waste, and sawdust mixed biochar; (2) assess the efficiency of biochar-composting combined amendment materials for reducing odor emissions and their maturity. The raw materials including food waste (FW), straw dust (SD), and biochar (BC) were prepared and homogeneously mixed with the weight ranging from 120.0 kg to 135.8 kg with five treatments, BC0 (Control), BC1 (5 % biochar), BC2 (5 % distilled water washed biochar), BC3 (10 % biochar), BC4 (20 % biochar). Adding biochar could change physicochemical properties such as temperature, moisture, and pH during composting. The results indicated applying biochar-composting covering to minimalized NH3 and H2S aided by higher porous structure and surface functional groups. Among trials, biochar 20 % obtained the lowest NH3 (2 ppm) and H2S (3 ppm) emission on day 16 and stopping their emission on day 17. The NH3/NH4+ adsorption on large specific surface areas and highly porous micro-structure of biochar lead to reduced nitrogen losses, while nitrification (NH4+ ➔ NO2- ➔ NO3-) may also contribute to nitrogen retention. The H2S concentration decreased with increasing the biochar proportion, suggesting that biochar could reduce the H2S emission. Correlation analysis illustrated that temperature, moisture, and oxygen are the most critical factors affecting H2S and NH3 emissions (p <0.05). The physicochemical properties and seed germination index indicated that the compost was mature without phytotoxicity. These novelty findings illustrated that the biochar amendment is an effective solution to reduce odor emission and enhances the maturity of compost mixture, which is promising to approach in real-scale conditions and could apply in agricultural fields.

Contour ripping is more beneficial than composted manure for restoring degraded rangelands in Central Texas.

Rangelands in the United States that have been the site of military training exercises have suffered extensive ecological damage, largely because of soil compaction, creation of ruts, and damage to or destruction of vegetation--all of which lead to higher runoff and accelerated erosion. In this paper we report on a study carried out within the Fort Hood Military Reservation in Central Texas, where we evaluated the extent to which application of composted dairy manure and contour ripping affect soil infiltrability, amount of runoff, and nutrient concentrations in runoff. We conducted experiments at two locations, using rainfall simulation at one and monitoring discharge from small (0.3-ha) watersheds at the other. At the rainfall simulation site, we used six levels of compost application: 4, 8, 12, 16, 20, and 24 Mg/ha. We found that compost application had little effect on runoff, soil infiltration, sediment production, or nutrient concentrations in the runoff--except at the micro-watershed scale (12 and 24 Mg/ha); in this case, nutrient concentrations in runoff were initially high (for the rainfall simulations done immediately after compost application). In contrast, contour ripping--carried out 22 months after compost application on two of the micro-watersheds--was highly effective: runoff on the treated micro-watershed was reduced by half compared with the untreated micro-watershed. Our results suggest that (1) one-time applications of composted dairy manure do little to enhance infiltration of degraded rangelands over the short term (at the same time, these experiments demonstrated that compost application poses very little risk to water quality); and (2) for degraded rangelands with limited infiltration capacity, contour ripping is an effective strategy for increasing infiltration rates.

Mechanism of digestate-derived biochar on odorous gas emissions and humification in composting of digestate from food waste.

Emissions of odorous gases and prolonged composting duration are the key concerns in the composting of digestate from food waste (DFW). In this study, different amounts of biochar derived from DFW (BC-DFW) were introduced in the composting process of DFW to decrease the emissions of ammonia (NH3) and volatile sulfur compounds (VSCs) and composting duration. The addition of BC-DFW increased the temperature and germination index during DFW composting. The group with 25% BC-DFW exhibited a 30% smaller composting duration. Significant amounts of NH3 and VSCs emissions were observed in the initial phase of DFW composting. Dimethyl disulfide (DMDS) was a prominent contributor to the odor associated with VSCs. The addition of BC-DFW facilitated the adsorption of NH3 and VSCs, and the corresponding contents decreased by 5-21% and 15-20%, respectively. Moreover,the BC-DFW accelerated the transformation of ammonium-nitrogen (NH4+-N) to nitrate-nitrogen (NO3--N), thereby alleviating the NH3 volatilization. The addition of 25% BC-DFW minimized the NH3 emission and enhanced the generation of humic-acid-like matter, thereby promoting humification. Therefore, the addition of 25% BC-DFW was optimal for promoting the degradation of organic matter and humification and odor emission reduction (e.g., NH3, DMDS).

Insight into how fertilization strategies increase quality of grape (Kyoho) and shift microbial community.

Organic and bioorganic fertilizers were increasingly used for agricultural soil. However, little is known on what kind of organic fertilizer application strategies can promote grape production well and how appropriate fertilization strategies improve soil properties and shift microbial community. This study investigated the improvement in soil physicochemical properties as well as their relations with microbial community structure and grape quality under different fertilization strategies. Our results found that (bio)organic fertilizer (CF1, CF2, and BF) especially combined application of organic and bioorganic fertilization (CBF) had smaller effects on electrical conductivity (EC) and pH, while it improved soil nutrients including N, P, K, and organic matter (OM) well, thereby promoting the grape quality comparing to the group without any fertilizer (CK) and with chemical fertilizer (NPK). Especially, the concentrations of Cr, Hg, Zn, and Cu were reduced by 13.63%, 12.50%, 12.52%, and 11.75% in CBF, respectively. Additionally, CF1, CF2, and BF, especially CBF, optimized the communities' composition and increased the abundance of some plant probiotics such as Solirubrobacter and Lysobacter. Nevertheless, excessive application of organic fertilizer derived from livestock manure could cause the accumulation of heavy metals such as Zn and Cu in soil and leaves, which could further influence the grape quality. Additionally, the structure of microbial communities was also changed possibly because some bacterial genera showed distinct adaptability to the stress of heavy metals or the utilization capacity of N, P, K, and OM. Our results demonstrated that combined application of organic and bioorganic fertilization showed a great influence on soil physicochemical properties, whose positive changes could further optimize microbial communities and facilitate the promotion of grape quality.

Ecological Responses of Maize Rhizosphere to Antibiotics Entering the Agricultural System in an Area with High Arsenicals Geological Background.

Metal(loid)s can promote the spread and enrichment of antibiotic resistance in the environmental ecosystem through a co-selection effect. Little is known about the ecological effects of entering antibiotics into the environment with long-term metal(loid)s' resistance profiles. Here, cow manure containing oxytetracycline (OTC) or sulfadiazine (SA) at four concentrations (0 (as control), 1, 10, and 100 mg/kg) was loaded to a maize cropping system in an area with high a arsenicals geological background. Results showed that exogenous antibiotics entering significantly changed the nutrient conditions, such as the concentration of nitrate nitrogen, ammonium nitrogen, and available phosphorus in the maize rhizosphere soil, while total arsenic and metals did not display any differences in antibiotic treatments compared with control. Antibiotics exposure significantly influenced nitrate and nitrite reductase activities to reflect the inhibition of denitrification rates but did not affect the soil urease and acid phosphatase activities. OTC treatment also did not change soil dehydrogenase activities, while SA treatment posed promotion effects, showing a tendency to increase with exposure concentration. Both the tested antibiotics (OTC and SA) decreased the concentration of arsenite and arsenate in rhizosphere soil, but the inhibition effects of the former were higher than that of the latter. Moreover, antibiotic treatment impacted arsenite and arsenate levels in maize root tissue, with positive effects on arsenite and negative effects on arsenate. As a result, both OTC and SA treatments significantly increased bioconcentration factors and showed a tendency to first increase and then decrease with increasing concentration. In addition, the treatments decreased translocation capacity of arsenic from roots to shoots and showed a tendency to increase translocation factors with increasing concentration. Microbial communities with arsenic-resistance profiles may also be resistant to antibiotics entering.