Land Application Of Animal Manure Research Articles

Identifying the spatiotemporal vulnerability of soils to antimicrobial contamination through land application of animal manure in Minnesota, United States

Antimicrobials may reach the soil environment from a variety of sources and pathways, including land application of human biosolids and animal manure. Once in soil, antimicrobials can affect the abundance and activity of soil microorganisms and exert selection pressures that enhance the emergence and spread of antimicrobial resistance (AMR). To mitigate the spread of AMR it is important to understand the spatial and temporal interactions between antimicrobials and soil. The goal of this study was to assess the vulnerability of Minnesota (U.S.) soil to contamination with specific antimicrobial compounds at temperatures experienced throughout the year. Soil contamination potential was estimated based upon specific antimicrobial drug binding and permanence, and average monthly temperature. Minnesota soil vulnerability was estimated by incorporating spatially explicit soil contamination potential, land cover type, and livestock density. Assessment of antimicrobials used in livestock production showed that soils are most vulnerable to antimicrobial contamination in southwestern Minnesota, to enrofloxacin, chlortetracycline, and oxytetracycline, and in the months of April and October. While the assessment herein was not based on actual on-farm antimicrobial use data and subsequent excretion of antimicrobial metabolites into the environment, this study provides an overview of the spatial and temporal potential for Minnesota soil to be contaminated by several antimicrobial drugs and demonstrates how specific vulnerability assessments might be conducted for geographic areas with known exposure (e.g., cropland fertilized with livestock manure and/or human biosolids). Such assessments might be used to identify best practices for mitigating antimicrobial exposure to soils and guide additional research to understand the role of environmental antimicrobial contamination in the problem of AMR.

Hydrogeophysical Characterization of Swine Effluent Amended Soils in Mantled Karst

Highlights Animal effluents can be detected in soils after minimal applications using non-intrusive characterization techniques. Swine effluent in soil produces measurable electrical signatures in the absence of chemical signatures. Electrical resistivity imaging can determine soil thickness and identify rapid transport pathways in the subsurface. Dietary additives may be good proxies to detect swine effluent in soils. Abstract. Land application of animal manures is useful for increasing many beneficial properties of soil that include fertility, productivity, and overall soil health, but can pose risks to water quality if not properly applied, especially in karstic formations. A study was carried out to assess the use of electrical resistivity and soil sampling to better characterize the transport of applied swine effluent within a mantled karst system and to assess the potential for rapid transport of swine effluent represented by Zn and other metals commonly found in effluent. This hydrogeophysical investigation was conducted at three sites, all permanent pastures, along Big Creek near Mount Judea, AR, USA, that are underlain by the Boone Limestone formation that is home to the Buffalo National River. To determine if surface electrical geophysics could be utilized to monitor the applied swine effluent within a mantled karst riparian system, this study measured the bulk electrical properties of the subsurface, characterized soil properties at the surface, and used reactive transport modeling. Electrical resistivity imaging (ERI) showed soils at sites with applied effluent were more electrically conductive than a background site. A comparison of ERI and soil sampling bulk datasets demonstrated strong trends between bulk resistivity and fluid conductance. These results enabled a more accurate definition of soil characteristics, the epikarst zone, and bedrock, along with anticipated subsurface chemical transport. Keywords: Electrical Resistivity Imaging, Epikarst detection, Soil characterization, Swine Effluent.

Transmission Routes of the Microbiome and Resistome from Manure to Soil and Lettuce.

The land application of animal manure can introduce manure microbiome and resistome to croplands where food crops are grown. The objective of this study was to characterize the microbiome and resistome on and in the leaves of lettuce grown in manured soil and identify the main transmission routes of microbes and antibiotic resistance genes (ARGs) from soil to the episphere and endosphere of lettuce. Shotgun metagenomic results show that manure application significantly altered the composition of the microbiome and resistome of surface soil. SourceTracker analyses indicate that manure and original soil were the main source of the microbiome and resistome of the surface soil and rhizosphere soil, respectively. Manure application altered the microbiome and resistome in the episphere of lettuce (ADONIS p < 0.05), and surface soil accounted for ∼81% of the microbes and ∼62% of the ARGs in episphere. Manure application had limited impacts on the microbiome and resistome in the endosphere (ADONIS p > 0.05). Our results show that manure-borne microbes and ARGs reached the episphere primarily through surface soil and some epiphytic microbes and ARGs further entered the endosphere. Our findings can inform the development of pre- and postharvest practices to minimize the transmission of manure-borne resistome from food crops to consumers.

Veterinary antibiotics in soils: Environmental processes, ecotoxicity, and risk mitigation

<p indent=0mm>Concentrated animal feeding operations have long extensively used antibiotics to prevent and treat infectious animal diseases and promote the growth of farmed animals, which have resulted in discharges of large quantities of un-metabolized veterinary antibiotics into agricultural soils along with the land application of animal manure. These veterinary antibiotics in soils could exert a range of ecotoxicological effects and even induce the emergence and development of antimicrobial-resistant microbes and genes, which pose a potential threat to human health. This review provides a systematic overview of the transport and fate processes of antibiotics in the soil environment and the corresponding mechanism, their ecotoxicological effects on crops, soil fauna, and soil microorganisms, and the strategies that can be used to mitigate the risk of antimicrobial pollution and the related mechanism. The major environmental processes of antibiotics in soil, including adsorption/desorption, biodegradation, and abiotic degradation, all strongly depend on the soil’s physical and chemical properties (e.g., pH and organic matter content) and the chemical structures and properties of antibiotics (e.g., functional group and hydrophobicity). The ecotoxicological effects of veterinary antibiotics on crops, soil fauna, and soil microorganisms are mainly determined by their types and concentrations and the soil’s physical and chemical properties. Antibiotic degradation during manure composting and anaerobic digestion primarily occurs through biodegradation and hydrolysis. The antibiotics in manure can be effectively degraded by high-temperature pyrolysis. In addition, biochar and graphene-based composite materials can stabilize the antibiotics in soils through hydrogen bonding, surface complexation, electrostatic interaction, and ion exchange. Important questions that must be addressed and recommendations for future research are proposed herein based on the summary of the recent research progresses on soil pollution by antibiotics.

Interaction of pig manure-derived dissolved organic matter with soil affects sorption of sulfadiazine, caffeine and atenolol pharmaceuticals

Pharmaceutically active compounds (PhACs) released into the environment have an adverse impact on the soil and water ecosystem as well as human health. Sorption of PhACs by soils and its potential modification through introduced DOM in the applied animal manure or treated wastewater (TWW) determines the mobility and environmental relevance of PhACs. Sulfadiazine, caffeine and atenolol were selected as target PhACs to investigate their sorption behaviors by five selected arable soils in the absence and presence of pig manure DOM. Sulfadiazine was least sorbed, followed by caffeine and atenolol according to the Freundlich sorption isotherm fit (soil average Kf [μg(1−n) mLn g−1] 4.07, 9.06, 18.92, respectively). The addition of manure DOM (31.34 mg C L−1) decreased the sorption of sulfadiazine and especially of caffeine and atenolol (average Kf 3.04, 6.17, 5.79, respectively). Freundlich sorption isotherms of the PhACs became more nonlinear in the presence of manure DOM (Freundlich exponent n changed from 0.74–1.40 to 0.62–1.12), implying more heterogeneous sorption of PhACs in soil–DOM binary systems. Sorption competition of DOM molecules with sulfadiazine and caffeine mostly contributed to their decreased soil sorption when DOM was present. In contrast, the formation of DOM–atenolol associates in the solution phase caused the largely decreased soil sorption of atenolol in the presence of DOM. It is suggested that DOM concentration (e.g., ≥ 60 mg C L−1) and its interaction with PhACs should be taken into consideration when assessing the environmental impact of land application of animal manure or irrigation with TWW.

Bacterial communities regulate temporal variations of the antibiotic resistome in soil following manure amendment

The increasing emergence of antibiotic-resistant genes (ARGs) represents a global threat to human health. Land application of animal manure is known to contribute considerably to the propagation and dispersal of antibiotic resistance in agro-ecosystems. Yet, the primary determinants of the fate of the soil resistome remain obscure. In this study, a pot experiment was conducted to examine temporal changes in ARGs, mobile genetic elements (MGEs), and bacterial communities in a weakly developed loamy soil (an entisol known as calcareous purple soil) upon addition of pig or chicken manure. On the day of manure application, substantial increases in the diversity and relative abundance of ARGs were observed in soil amended with raw pig manure. At the same time, no obvious changes were observed for soil amended with chicken manure. Antibiotic resistance in pig manure-amended soils rapidly decreased over time to a level that was still higher than that of unamended soil at 100 days after manure application. The results of the Mantel test and Procrustes analysis indicated that ARG profiles in soil were significantly correlated with the structure of the bacterial phylogeny. Variation partitioning analysis further revealed that the bacterial community played a major role in regulating the temporal changes in ARGs in soil following manure application. Increased numbers and relative abundances of MGEs and their significant positive correlations with ARGs were observed, which suggest that a potential contribution from lateral gene transfer to the persistence and spread of ARGs should not be overlooked. Overall, our findings provide a better understanding of the mechanisms underlying the dynamics of ARGs in entisols following manure application and have practical implications for managing manure applications in entisols of the study area and other areas.

Antibiotic resistance genes and bacterial communities in cornfield and pasture soils receiving swine and dairy manures

Land application of animal manure could change the profiles of antibiotic resistant bacteria (ARB), antibiotic resistance genes (ARGs) and bacterial communities in receiving soils. Using high-throughput real-time quantitative PCR and 16S rRNA amplicon sequencing techniques, this study investigated the ARGs and bacterial communities in field soils under various crop (corn and pasture) and manure (swine and dairy) managements, which were compared with those of two non-manured reference soils from adjacent golf course and grassland. In total 89 unique ARG subtypes were found in the soil samples and they conferred resistance via efflux pump, cellular protection and antibiotic deactivation. Compared to the ARGs in the golf course and grassland soils (28 and 34 subtypes respectively), manured soils generally had greater ARG diversity (36–55 subtypes). Cornfield soil frequently receiving raw swine manure had the greatest ARG abundance. The short-term (one week) application of composted and liquid swine manures increased the diversity and total abundance of ARGs in cornfield soils. Intriguingly the composted swine manure only marginally increased the total abundance of ARGs, but substantially increased the number of ARG subtypes in the cornfield soils. The network analysis revealed three major network modules in the co-occurrence patterns of ARG subtypes, and the hubs of these major modules (intl1-1, vanC, and pncA) may be candidates for selecting indicator genes for surveillance of ARGs in manured soils. The network analyses between ARGs and bacteria taxa revealed the potential host bacteria for the detected ARGs (e.g., aminoglycoside resistance gene aacC4 may be mainly carried by Acidobacteriaceae). Overall, this study highlighted the potentially varying impact of various manure management on antibiotic resistome and microbiome in cornfield and pasture soils.

Pressurized liquid extraction of six tetracyclines from agricultural soils

Veterinary antibiotics used in agriculture can be introduced into the environment through land application of animal manure, accumulating in soils and groundwaters and posing a significant risk to human health and animal well-being. As the analysis of tetracyclines in soil is challenging due to their strong interaction with soil minerals and organic carbon, the objective of this study was to develop a reliable and reproducible method for quantitative analysis of chlortetracycline and oxytetracycline, and their respective metabolites in soils. A method based on pressurized liquid extraction (PLE) with in-cell clean-up was developed for the extraction of chlortetracycline and oxytetracycline and four likely metabolites from a set of four soils. Optimized conditions included a cell size of 22 mL, soil loading of 5 g, pH of 8.0, methanol:water ratio of 3:1, 50 °C, and two cycles. Soil extracts were analysed by high-performance liquid chromatography (HPLC) coupled with ion trap mass spectrometry (MS). Recoveries of seven tetracyclines from soil ranged from 41% to 110%. The limits of detection for tetracyclines were 0.08–0.3 µg g−1 soil, and intra- and inter-day variation ranged from 0.12–0.34%. The proposed PLE method is suitable for quantification of tetracyclines in agricultural soils at typical concentrations expected in contaminated environments.

Antibiotic resistance genes and associated bacterial communities in agricultural soils amended with different sources of animal manures

Land application of animal manures is a major dissemination route for antibiotic resistance genes (ARGs) in agro-ecosystems, which are a potential risk to public health if they migrate into the food chain. Despite the fact that animal manure is a rich reservoir of ARGs our knowledge of the impacts of different types and amounts of animal manures on the temporal succession of a wide array of ARGs and potential ARG-hosts remains limited. Here, we constructed soil microcosms amended with two levels of swine, poultry or cattle manures to explore the time-course patterns of ARGs, mobile genetic elements (MGEs) including integrons and transposons, and bacterial communities. The high-throughput quantitative PCR detected 260 unique ARGs, and the application of all manure types, especially at the higher concentration (80 mg manure g−1 soil), significantly increased the diversity and abundances of ARGs and MGEs. The abundance of ARGs in manured soils declined over time, but was still higher than that in untreated soils after 120 days, indicating the persistence of ARGs in manured soils. The next-generation sequencing revealed a clear shift in the bacterial community compositions of manured soils during the incubation. Mantel test and network analysis revealed that the ARG profile was strongly correlated with the bacterial community compositions. Variation partitioning analysis, and structure equation models, further indicated that bacterial phylogeny played a primary role in shaping the ARG profiles in manured soils. However, the significant correlation between the abundances of MGEs and ARGs suggested that the potential effects of horizontal gene transfer on the persistence of ARGs should not be overlooked. In addition, soil properties, which were strongly affected by the added manures, could also affect the ARG patterns. These findings demonstrated the temporal patterns and dissemination risk of ARGs in manured soils, which might contribute to the development of effective strategies to minimise the spread of ARGs in agro-ecosystems.

Heavy metals accumulation in soil after 4 years of continuous land application of swine manure: A field-scale monitoring and modeling estimation

Land application of animal manure has been encouraged widely in China. This presents a risk of heavy metals (HMs) accumulation in the soil due to their high contents in the feeds and additives. A 4-year field-scale study was conducted to monitor and estimate HMs accumulation in the soil with land application of swine manure. The results show a clear tendency for As, Hg, Cr, Cu, Zn and Mn to increase gradually with the application duration, yielding an average annual increase of 0.57, 0.011, 6.20, 5.64, 22.58, and 23.45 mg kg−1, respectively, at the annual application rate of about 250 t ha−1 of swine manure. The estimation from the mass balance modeling indicates the environmental risk of Cd, Cu and Zn will exceed the threshold levels for agricultural soils in China in the next 10–50 years. Determination of a suitable application rate of animal manure would be the first consideration for mitigating the environmental risk of HMs currently.

Simultaneous Determination of Trace Levels of 12 Steroid Hormones in Soil Using Modified QuEChERS Extraction Followed by Ultra Performance Liquid Chromatography–Tandem Mass Spectrometry (UPLC–MS/MS)

Steroid hormones, mainly secreted by vertebrates, are discharged into the soil environment through surface runoff and land application of animal manure, sewage sludge, and organic fertilizers. The adequate analytical methods for steroid hormones in soil are lacking due to the requirement of rigorous sample pre-treatment. In this study, a rapid and effective modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) method was developed for trace simultaneous analysis of 12 steroid hormones (estrogen, androgens, and progestogens) in soil samples using ultra performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS). Samples were extracted by the mixture of acetonitrile and acetate buffer, and then cleaned with PSA/C18 absorbents. The QuEChERS method was validated by evaluating the linearity, repeatability, accuracy and precision. A suitable linear relationship was obtained in the mass concentration range of 1–100 ng g−1 with high correlation coefficients (> 0.9927). The method enabled the determination of the target analytes with limits of detection between 0.0014 and 0.462 ng g−1 and limits of quantification between 0.0047 and 1.54 ng g−1. Soil was spiked at 5, 50 and 100 ng g−1, and the recoveries ranged from 75.17 to 110.33% with relative standard deviations ≤ 9.45. The developed method was successfully applied to the analysis of soil samples collected in Beijing, and five hormones (E1, E3, αE2, And, and Tes) were detected with the concentrations ranging from 0.35 to 7.09 ng g−1.

Long-term manure application increased the levels of antibiotics and antibiotic resistance genes in a greenhouse soil

Land application of animal manure, as an important agronomic practice, represents a potential route to disseminate antibiotic resistance genes (ARGs) into the soil environment. Previous studies have demonstrated that manure-derived ARGs and pathogenic organisms rapidly decline over time following manure application, however, the impacts of long-term and repeated application of animal manure on the diversity and abundance of soil ARGs remain less understood. Here, we investigated the diversity and abundance of ARGs in greenhouse soils with long-term dairy cattle and chicken manure (DM and CM) application, and the half-life of antibiotic resistant bacteria (ARB) isolated from manured soils in Taiyuan, China. Both DM and CM significantly improved the levels of residual antibiotics, the abundances of ARGs, intI1 and soil organic carbon and total nitrogen that there was strong link between them. The half-life of ARB was different, and the correlations of ARGs, intI1 and tnpA genetic elements extracted from ARB with culture times were different. The significantly positive link was between the population of resistance bacteria and the half-life. Our finding suggested that both the levels of antibiotics and the stability of ARGs will determine the diversity and abundance of ARGs in manured soils.

Temporal succession of soil antibiotic resistance genes following application of swine, cattle and poultry manures spiked with or without antibiotics

Land application of animal manure is a common agricultural practice potentially leading to dispersal and propagation of antibiotic resistance genes (ARGs) in environmental settings. However, the fate of resistome in agro-ecosystems over time following application of different manure sources has never been compared systematically. Here, soil microcosm incubation was conducted to compare effects of poultry, cattle and swine manures spiked with or without the antibiotic tylosin on the temporal changes of soil ARGs. The high-throughput quantitative PCR detected a total of 185 unique ARGs, with Macrolide-Lincosamide-Streptogramin B resistance as the most frequently encountered ARG type. The diversity and abundance of ARGs significantly increased following application of manure and manure spiked with tylosin, with more pronounced effects observed in the swine and poultry manure treatments than in the cattle manure treatment. The level of antibiotic resistance gradually decreased over time in all manured soils but was still significantly higher in the soils treated with swine and poultry manures than in the untreated soils after 130 days’ incubation. Tylosin-amended soils consistently showed higher abundances of ARGs than soils treated with manure only, suggesting a strong selection pressure of antibiotic-spiked manure on soil ARGs. The relative abundance of ARGs had significantly positive correlations with integrase and transposase genes, indicative of horizontal transfer potential of ARGs in manure and tylosin treated soils. Our findings provide evidence that application of swine and poultry manures might enrich more soil ARGs than cattle manure, which necessitates the appropriate treatment of raw animal manures prior to land application to minimise the spread of environmental ARGs.

Effect of swine liquid manure application in paddy field on water quality, soil fertility and crop yields

Land application of animal manure has been accepted as an effective method and disposal option, which has economic, environmental and social benefits, while also sometimes exists questions about its impact on soil and water quality and crop yields. This paper presents a field-scale study in Chongming Island, Shanghai, China, where land application of digested swine liquid manure with chemical fertilizer supplement in paddy field (SMC field) was conducted to study the short-term effect on soil quality in different depth, pollutant losses by surface runoff, pollutant concentrations in groundwater and crop yields, compared to conventional paddy field with land application of pure chemical fertilizer (CKC field). The results indicated that: (1) in groundwater, the concentrations of chemical oxygen demand (COD), nitrate nitrogen (Nitrate-N), total phosphorus (TP) and dissolved phosphorus (DP) were significantly increased by 24.69, 17.04, 11.76 and 21.05%, respectively, in the SMC field; (2) in surface runoff, the loss loading of COD, TP and DP was significantly increased by 32.18, 15.46 and 28.13%, respectively, while the ammonia nitrogen (Ammonia-N) was significantly decreased by 31.81%, in the SMC field; (3) in the different depth of soil, the contents of total nitrogen presented a greater decrease in the SMC field, while the contents of TP presented a greater decrease in the CKC field, compared to the properties of original soil; (4) for the crop yields, there was no significant difference between the SMC and CKC field. These practices had proved the feasibility for land application of swine liquid manure in the paddy field, and this approach could be extended after being rate modified to concern the nutrient utilization and pollution risk to water environment.

The Role of Organic Carbon in Natural and Synthetic Oestrogens Sorption onto Soils

Among the compounds implicated as Environmental Endocrine Disruptors (EEDs), the most potent to alter the normal functions of the endocrine systems of organisms and humans are the natural and synthetic oestrogen. They are hydrophobic and ubiquitous and remain in the final effluents for the vast majority of sewage treatment plant. Land application of animal manures and sewage sludge as fertilizers has been reported to increase the amount of hormones in soil. However, the information on the factor that influences the occurrence of these compounds in this environmental compartment is limited. This study investigates the sorption affinity of these oestrogens on soils by determining its soil-water partition coefficient (Kd), sorption coefficient normalised to organic carbon (Koc) and octanol-water partition coefficient (Kow). In this study, different percentage of organic carbon was used. The results obtained shows that the Kow is a good predictor of sorption among contaminants as the affinity of oestrogens in soils is strongly dependent to their Kow values. This study also shows that the solid-water partition coefficient (Kd) of all oestrogens have good correlation to the organic carbon content. The calculated sorption coefficient normalised to organic carbon (Koc) indicate a strong association of all oestrogens with organic carbon. Therefore it is concluded that the organic carbon is pertinent to the sorption of oestrogens in soils.

Reduction of estrone to 17 β-estradiol in the presence of swine manure colloids

Land application of animal manure and municipal biosolids to improve soil fertility carries the risk of adding to aquatic ecosystems contaminants that can disrupt the endocrine systems of aquatic organisms. This study explored the fate of two estrogens, 17 β-estradiol (E2) and estrone (E1), in the presence of organic colloids derived from swine manure. Most reports concerning environmental estrogens indicate a degradation/transformation pathway that leads to decreased estrogenicity, that is, E2 is transformed to E1 and potentially to other daughter products. However, in this study we found that within 24h the reverse reaction was possible (E1 transforming to E2) in a swine manure colloidal suspension closed to the atmosphere. The reaction occurred after approximately the same 24-h period in separate colloidal suspensions of swine manure that had been initially incubated with E2 or with E1. In the experiment with E2, there was an apparent complete reversal of the solution estrogen form, from E2 to E1 and then back to E2. Our observations support the concern that environmentally relevant estrogens have the potential to increase in estrogenicity and/or to persist under reducing conditions.

Phosphorus release from dairy manure, the manure-derived biochar, and their amended soil: effects of phosphorus nature and soil property.

Land application of animal manure often risks excessive phosphorus (P) release into the surrounding water. The aim of this study was to convert the dairy manure into biochar, followed by their application into soil, and then to investigate P release from the manure and its derived biochar as well as from the manure- and biochar-amended soil. The results showed that P release was reduced when the manure was converted into biochar due to formation of less-soluble whitlockite [(Ca, Mg)(PO)]. The cumulative P released from biochar over 240 h was 0.26 g kg, a 76% reduction of that from the manure (1.07 g kg). The kinetic release of P from the manure was determined by the fast desorption process and was better fitted to Elovich equation, whereas P release from biochar was initially controlled by the diffusion process and then by slow but steady dissolution of (Ca,Mg)(PO), following the parabolic diffusion and linear models, respectively. When the manure or biochar was incorporated into the soil, P release in the CaCl and simulated acid rain water extraction from biochar-amended soil was consistently lower than that from the manure-amended soil during 210-d incubation. The lower P release in the biochar-amended soil was determined by stable P form (Ca, Mg)(PO) in the biochar itself, but less from the soil property effect. Results indicated that initial high P release from manure can be mitigated by converting the manure into biochar.

Kinetics and Modeling of Degradation of Ionophore Antibiotics by UV and UV/H2O2

Ionophore antibiotics (IPAs), one of the major groups of pharmaceuticals used in livestock industry, have been found to contaminate agricultural runoff and surface waters via land application of animal manures as fertilizers. However, limited research has investigated the means to remove IPAs from water sources. This study investigates the degradation of IPAs by using ultraviolet (UV) photolysis and UV combined with hydrogen peroxide (UV/H2O2) advanced oxidation process (AOP) under low-pressure (LP) UV lamps in various water matrices. Three widely used (monensin, salinomycin, and narasin) and one model (nigericin) IPAs exhibit low light absorption in the UV range and degrade slowly at the light intensity of 3.36 × 10(-6) Einstein·L(-1)·s(-1) under UV photolysis conditions. However, IPAs react with hydroxyl radicals produced by UV/H2O2 at fast reaction rates, with second-order reaction rate constants at (3.49-4.00) × 10(9) M(-1)·s(-1). Water matrix constituents enhanced the removal of IPAs by UV photolysis but inhibited UV/H2O2 process. A steady-state kinetic model successfully predicts the impact of water constituents on IPA degradation by UV/H2O2 and determines the optimal H2O2 dose by considering both energy consumption and IPA removal. LC/MS analysis of reaction products reveals the initial transformation pathways of IPAs via hydrogen atom abstraction and peroxidation during UV/H2O2. This study is among the first to provide a comprehensive understanding of the degradation of IPAs via UV/H2O2 AOP.

Accelerated Biodegradation of Veterinary Antibiotics in Agricultural Soil following Long-Term Exposure, and Isolation of a Sulfamethazine-degrading Microbacterium sp.

The World Health Organization has identified antibiotic resistance as one of the top three threats to global health. There is concern that the use of antibiotics as growth promoting agents in livestock production contributes to the increasingly problematic development of antibiotic resistance. Many antibiotics are excreted at high rates, and the land application of animal manures represents a significant source of environmental exposure to these agents. To evaluate the long-term effects of antibiotic exposure on soil microbial populations, a series of field plots were established in 1999 that have since received annual applications of a mixture of sulfamethazine (SMZ), tylosin (TYL), and chlortetracycline (CTC). During the first 6 yr (1999-2004) soils were treated at concentrations of 0, 0.01 0.1, and 1.0 mg kg soil, in subsequent years at concentrations of 0, 0.1, 1.0, and 10 mg kg soil. The lower end of this concentration range is within that which would result from an annual application of manure from medicated swine. Following ten annual applications, the fate of the drugs in the soil was evaluated. Residues of SMZ and TYL, but not CTC were removed much more rapidly in soil with a history of exposure to 10 mg/kg drugs than in untreated control soil. Residues of C-SMZ were rapidly and thoroughly mineralized to CO in the historically treated soils, but not in the untreated soil. A SMZ-degrading sp. was isolated from the treated soil. Overall, these results indicate that soil bacteria adapt to long-term exposure to some veterinary antibiotics resulting in sharply reduced persistence. Accelerated biodegradation of antibiotics in matrices exposed to agricultural, wastewater, or pharmaceutical manufacturing effluents would attenuate environmental exposure to antibiotics, and merits investigation in the context of assessing potential risks of antibiotic resistance development in environmental matrices.

Town-based spatial heterogeneity of nutrient balance and potential pollution risk of land application of animal manure and fertilizer in Shanghai, China

Land application of animal manure has been proven to be an efficient and convenient approach for animal manure treatment and resource recycling that has been encouraged in Shanghai suburbs in recent years. Based on livestock and poultry inventories, the available cropland base, and the application amounts of chemical fertilizer in each town of Shanghai, the nutrient supplies from animal manure, nutrient demands of croplands, and the nutrient inputs from chemical fertilizer were calculated. The nutrient balance and potential pollution risk of land application of animal manure and chemical fertilizer were evaluated by a calculated nutrient balance index (NBI) and nutrient pollution index (NPI). The results show that the annual total nitrogen (TN) demand of croplands was about 46,833 tons while the annual total phosphorus (TP) demand was around 11,373 tons. The annual TN supply from animal manure was 23,341 tons while the annual TP supply was 9,581 tons. The annual TN input from chemical fertilizer was 112,550 tons while the TP input was 14,782 tons. For land application of animal manure, more than 10% of all the towns had a NBI > 1 for TN, while more than 20% had a NBI > 1 for TP. For land application of chemical fertilizer, more than 80% of all the towns had a NBI > 1 for TN, while more than 60% had a NBI > 1 for TP. For the pollution risk of land application of animal manure and chemical fertilizer, there were more than 90% of all the towns with NPI > 1 for TN, while more than 80% with NPI > 1 for TP. For the entire city, the local croplands could agronomically use all the animal manure if it were properly distributed and applied reducing the need for large quantities of chemical fertilizer application.