Survival of Escherichia coli O157:H7 and Salmonella typhimurium in cow manure and cow manure slurry

An exponential linear destruction was observed for Escherichia coli O157:H7 and Salmonella typhimurium in cattle manure and manure slurry stored at 4, 20 or 37 degrees C. The resulting decimal reduction times ranged from 6 days to 3 weeks in manure and from 2 days to 5 weeks in manure slurry. The main effects of time as well as temperature were pronounced with the most rapid destruction at 37 degrees C. The ammonia concentration in manure increased slightly during storage but did not exceed 0.1%. pH values in the deeper layers of manure remained constant except at 37 degrees C when the pH increased by 1 unit in 60 days. In the surface layers of manure, pH increased by 1.5-2 units, the oxidation-reduction potential of the manure declined rapidly to values below -200 mV. These changes do not seem to be reflected in changing rates of bacterial destruction. The observed order of destruction makes it possible to predict storage conditions (temperature and time) that will lead to a predetermined level of reduction of the two pathogens.     

Anaerobic co-digestion of desugared molasses with cow manure; focusing on sodium and potassium inhibition

Desugared molasses (DM), a syrup residue from beet-molasses, was investigated for biogas production in both batch and in continuously-stirred tank reactor (CSTR) experiments. DM contained 2-3 times higher concentration of ions than normal molasses, which could inhibit the biogas process. The effect of sodium and potassium concentration on biogas production from manure was also investigated. Fifty percent inhibition occurred at sodium and potassium concentration of 11 and 28 g/L, respectively. The reactor experiments were carried out to investigate the biogas production from DM under different dilutions with water and co-digestion with manure. Stable operation at maximum methane yield of 300 mL-CH₄/gVS-added was obtained at a mixture of 5% DM in cow manure. The biogas process was inhibited at DM concentrations higher than 15%. Manure was a good base substrate for co-digestion, and a stable anaerobic digestion could be achieved by co-digesting DM with manure at the concentration below 15% DM.     

Reduction of the resistome risk from cow slurry and manure microbiomes to soil and vegetable microbiomes

In cow farms, the interaction between animal and environmental microbiomes creates hotspots for antibiotic resistance dissemination. A shotgun metagenomic approach was used to survey the resistome risk in five dairy cow farms. To this purpose, 10 environmental compartments were sampled: 3 of them linked to productive cows (fresh slurry, stored slurry, slurry-amended pasture soil); 6 of them to non-productive heifers and dry cows (faeces, fresh manure, aged manure, aged manure-amended orchard soil, vegetables-lettuces and grazed soil); and, finally, unamended control soil. The resistome risk was assessed using MetaCompare, a computational pipeline which scores the resistome risk according to possible links between antibiotic resistance genes (ARGs), mobile genetic elements (MGEs) and human pathogens. The resistome risk decreased from slurry and manure microbiomes to soil and vegetable microbiomes. In total (sum of all the compartments), 18,157 ARGs were detected: 24% related to ansamycins, 21% to multidrugs, 14% to aminoglycosides, 12% to tetracyclines, 9% to β-lactams, and 9% to macrolide–lincosamide–streptogramin B. All but two of the MGE-associated ARGs were only found in the animal dejections (not in soil or vegetable samples). Several ARGs with potential as resistome risk markers (based on their presence in hubs of co-occurrence networks and high dissemination potential) were identified. As a precautionary principle, improved management of livestock dejections is necessary to minimize the risk of antibiotic resistance.     

Nitrogen and phosphorus removal rates using small algal turfs grown with dairy manure

Conservation and reuse of nitrogen (N) and phosphorus (P) from animalmanure is increasingly important as producers try to minimize transport ofthesenutrients from farms. An alternative to land spreading is to grow crops ofalgaeon the N and P present in the manure. The general goal of our research is toassess nutrient recovery from animal manure using attached algae. The specificobjective of this study was to evaluate the use of small subsections of algalturfs for determining N and P removal rates by attached algae under differentloading rates of dairy manure. Algae were grown in a laboratory–scalealgal turf scrubber (ATS) operated by recycling wastewater and adding manureeffluent daily. Replicate subsections (0.032 m²) ofalgal turf screens were removed and treated with five different loadings ofanaerobically digested dairy manure containing 5 to 80 mgL^–1 NH₄-N and 1 to 20 mgL^–1 PO₄-P over a 2-h incubationperiod. NH₄-N removal rates were biphasic with a fast initial ratefollowed by a slower rate. Biphasic rates were more pronounced for the lowestloading rates but less so for the higher ones. PO₄-P removal rateswere linear throughout the incubation period for all loading rates. N and Premoval rates increased with increasing loading rate and biomass. Inincubationsusing 1% dairy manure NH₄-N and PO₄-P removal ratesaveraged 0.72 and 0.33 g m^–2d^–1,respectively. These rates were approximately 5 to 8-fold lower than ratesmeasured on laboratory-scale ATS units using undisturbed turfs.     

三种集约化种植体系氮素平衡及其对地下水硝酸盐含量的影响

选取中国北方3种重要的集约化种植体系小麦玉米轮作、大棚蔬菜和果园,研究了3种体系年度氮素输入输出关系、土壤硝酸盐的累积、不同体系地下水硝态氮含量的动态变化.结果表明,大棚蔬菜年度化肥氮、有机肥氮、灌水带入的氮和总氮输入量分别为135.8、1881、402和36.56kg·hm^-2,分别为小麦玉米田的25、37.5、83.8和5.8倍,为果园的2.1、10.4、6.82和4.2倍.不同系统降水输入的氮在142～189kg·hm^-2之间.3个体系氮输出量分别为280、329和121kg·hm^-2.氮素年度盈余分别为349、332.7和74.6kg·hm^-2.0～90cm土层硝态氮累积量分别为22.1～2.75、1173和613kg·hm^-2,90～180cm土层硝态氮累积量分别为2.13～2.42、10.32和976kg·hm^-2.在0～180cm剖面中,小麦玉米田各层土壤硝态氮处于相对均一分布,大棚蔬菜以表层最高,30cm以下各层也远高于大田,果园土壤硝态氮累积随土壤深度而增加.3种体系均表现出硝酸盐的明显淋洗.大棚蔬菜区浅井地下水硝态氮含量99%超过了10mg·L^-1.而大棚深井和果园浅井超标率均为5%,小麦玉米深井为1%.大棚蔬菜区地下水硝态氮含量与井深呈指数函数降低关系.     

厦门城市降雨径流氮、磷污染特征

以厦门岛为研究对象,通过收集代表性样点的降雨径流水样,研究了厦门城市降雨径流中氮、磷浓度及输出特征。结果表明,来源不同的城市降雨径流中氮、磷浓度差异较大,溶解态总氮、硝态氮、氨态氮与总磷的含量分别为1.96~6.77、0.62~4.89、0.35~1.18和0.04~0.66 mg.L-1。降雨过程中氮、磷浓度总体上呈下降趋势,氮浓度波动较大,磷相对稳定。城市降雨径流氮、磷污染受降雨强度、车流量等多种因素影响。城市道路、商住区及工业区径流中氮、磷浓度较高,是城市非点源污染的主要来源,因此对这些区域应重点控制管理。     

利用Chlorella vulgaris C9-JN2010去除蓝藻-猪粪沼液废水中氮磷的研究

利用普通小球藻Chlorella vugaris C9-JN2010处理蓝藻-猪粪沼液废水,以实现废水无害化利用。实验考察了氮磷比和沼液浓度对小球藻生长及处理废水效果的影响,结果表明:在氮磷比(20:1)和沼液浓度(5%)条件下培养小球藻,藻细胞生长和废水处理效果最佳,最高细胞干重及生产强度分别为900.1 mg·L~(-1)和85.1 mg·L~(-1)·d~(-1),废水中总氮、总磷、氨氮的去除率分别为84.6%、95.9%和90.5%,对应去除强度分别为5.43 mg·L~(-1)·d~(-1)、0.30 mg·L~(-1)·d~(-1)和4.75 mg·L~(-1)·d~(-1)。利用小球藻可较彻底的去除蓝藻-猪粪沼液废水中氮、磷等营养,达到污水处理效果。     

Impacts on microbial communities and cultivable isolates from groundwater contaminated with high levels of nitric acid-uranium waste

Microbial communities were characterized at contaminated sites that had elevated levels of nitrate, nickel, aluminum, and uranium (up to 690 mM, 310 microM, 42 mM, and 30 microM, respectively). The bacterial community structure based upon clonal libraries of the SSU rRNA genes (screened clones = 876) was diverse at the background site, but the three acidic samples had decreased diversity and the majority of clones were closely related to Azoarcus and Pseudomonas species. Arthrobacter and Novosphingobium sequences were recovered from the background samples but not the acidic sites, and similar pseudomonad populations were present at the background and acidic sites albeit at different relative abundances. Heterologous sequence coverage analyses indicated the microbial communities at the contaminated sites were very similar (p = 0.001) but different from the background site. Bacterial isolates (n = 67) classified as beta-or gamma-Proteobacteria, high G+C Gram-positive or low G+C Gram-positive were obtained from the background and one contaminated sample, and some of the isolates had less than 95% sequence identity with previously observed microorganisms. Despite variations in nitrate and heavy metal levels and different proximities to the source ponds, the three acidic samples had similar microbial populations. However, the least contaminated site (lowest nitrate and aluminum) had increased diversity compared to the other acidic samples. The results suggested that the combined contamination has decreased the microbial diversity, and Azoarcus populations were observed at a drastically increased frequency compared to the background site that had a more even distribution of multiple taxa.     

Transformation and Transport of Nitrogen Forms in a Sandy Entisol Following a Heavy Loading of Ammonium Nitrate Solution: Field Measurements and Model Simulations

Understanding the factors influencing water and nutrient transport through soil profile is important for the efficient management of nutrient and irrigation to minimize nutrient leaching below the rootzone. Transport of NO₃-N and NH₄-N was studied in a Candler fine sand following a heavy loading of a liquid fertilizer containing ammonium nitrate. Both NO₃-N and NH₄-N transported quite rapidly (within 3?d) and accumulated above the clay layer at about depth of 2.7?m. The concentrations of NH₄-N and NO₃-N approached background levels throughout the soil profile by 184?d. More than 50% of ammonium and nitrate contained in the spilled solution leached from the entire depth of soil profile sampled during the first 95?d. The cumulative amount of rainfall during this period was 329?mm, which accounted for 65% of the total rainfall for the entire study period. The concentrations of NH₄-N and NO₃-N at various depths within the entire soil profile reasonably predicted by the Leaching Estimation and Chemistry Model (LEACHM) and compared favorably with the measured concentrations, however, there are few places with high concentrations. The cumulative amount of leachate at the bottom of the soil profile predicted by LEACHM represented 90% of total rainfall that occurred during the study period. This demonstrated a substantial potential for leaching of soluble nutrients through the sandy soil profile.     

固相反硝化技术同时去除地下水中的硝酸盐与农药进展

概述了固相反硝化技术及其特点,综述了固相反硝化技术在去除地下水中硝酸盐与农药的研究现状,分析了反应机理及当前研究中存在的问题,并在此基础上对固相反硝化的未来核心研究方向进行了展望。     

Nitrogen and phosphorus content of some temperate and tropical freshwater fishes

The nitrogen and phosphorus content of two temperate fishes, Rutilus rutilus and Perca fluviatilis , and six tropical fishes, Oreochromis niloticus , Cichla monoculus , Serrassalmus rhombeus , Plagioscion squamosissimus , Prochilodus brevis and Hoplias malabaricus , were investigated to test the hypothesis that variation in body P content and N:P ratio is related to body size. Regressions of %P and N:P ratios against fish size (length and mass) confirmed the hypothesis for P. fluviatilis and P. squamosissimus , suggesting that body size is an important factor driving body P content and N:P ratios in some fishes. Moreover, significant increases in %N and N:P ratio with body size was found for H. malabaricus , a common piscivorous fish of the Neotropics. Interspecific variation in %P and N:P ranged two-fold and significant differences ( P < 0·05) were found among the tested species. The mean ± s . d . elemental content across all fishes ( n = 170) was 10·35 ± 1·29% for N and 3·05 ± 0·82% for P, while the N:P ratio was 8·00 ± 2·14. Data on fish body nutrient content and ratio will improve parameterization of bioenergetics and mass balance models and help clarify the role of fishes in nutrient cycles in both temperate and tropical freshwaters.     

Nitrogen and phosphorus content in plant species of Mediterranean ecosystems in Greece

The values of nitrogen phosphorus ratios measured in green parts of evergreen sclerophylls, seasonal dimorphic, deciduous and herbaceous plants found in Mediterranean-type ecosystems of Greece, form a homogeneous group, which is comparable only with those of analogous ecosystems of California but not with Mediterranean systems of the southern hemisphere.Nomenclature follows: Tutin et al., 1964. Flora Europaea.Support of National Research Foundation (Greece) and NATO (SRG-12) is gratefully acknowledged.     

Community analysis of hydrogen-producing extreme thermophilic anaerobic microflora enriched from cow manure with five substrates

The present study analyzed the community structures of anaerobic microflora producing hydrogen under extreme thermophilic conditions by two culture-independent methods: denaturing gradient gel electrophoresis (DGGE) and clone library analyses. Extreme thermophilic microflora (ETM) was enriched from cow manure by repeated batch cultures at 75 degrees C, using a substrate of xylose, glucose, lactose, cellobiose, or soluble starch, and produced hydrogen at yields of 0.56, 2.65, 2.17, 2.68, and 1.73 mol/mol-monosaccharide degraded, respectively. The results from the DGGE and clone library analyses were consistent and demonstrated that the community structures of ETM enriched with the four hexose-based substrates (glucose, lactose, cellobiose, and soluble starch) consisted of a single species, closely related to a hydrogen-producing extreme thermophile, Caldoanaerobacter subterraneus, with diversity at subspecies levels. The ETM enriched with xylose was more diverse than those enriched with the other substrates, and contained the bacterium related to C. subterraneus and an unclassified bacterium, distantly related to a xylan-degrading and hydrogen-producing extreme thermophile, Caloramator fervidus.     

Effects of differentiated applications of fertilizer N on leaching losses and distribution of inorganic N in the soil

Summary Nitrogen fertilizer was applied to field plots at rates of 0, 50, 100, 150 and 200 N kg/ha yr, in order to determine the effects of differentiated N applications on drainage water and groundwater quality. Water samples, collected monthly or bimonthly from 1974 to 1983, were analysed for inorganic and total N content. In order to see the impact of residual N on leaching losses, soil samples were collected to a depth of 2 m in the N0, N100 and N200 plots, usually in September and April. Leaching of nitrate was moderate to the N100 level but increased substantially with increasing fertilization, up to 91 N kg/(ha-yr) for the highest application rate (N200), during the wet year of 1980/81. The losses were greatest during the fall, mainly due to high levels of N remaining in the soil after harvest combined with high precipitation. The N content of the groundwater did not show any significant correlation to the fertilization intensity. A buildup of inorganic N in the soil occurred only when excessive amounts of fertilizer were applied (N200), while the contents of the N0 and N100 treatments fluctuated around states of balance, approximately 45 and 70 N kg/ha respectively. Spring rape followed by winter wheat showed a great ability to reduce N contents in the tile effluent from highly fertilized plots (N150 and N200), even though the plots had received excessive amounts of fertilizer for several years. Results of this experiment in central Sweden demonstrate the importance of applying nitrogen fertilizer in balance with crop needs and of maintaining a growing crop cover as much of the time as possible in order to minimize water pollution.     

Nitrogen retention efficiency and nitrogen losses of a managed and phytodiverse temperate grassland

Maintaining nitrogen retention efficiency (NRE) is crucial in minimizing N losses when intensifying management of temperate grasslands. Our aim was to evaluate how grassland management practices and sward compositions affect NRE (1 − N losses/soil available N), defined as the efficiency with which soil available N is retained in an ecosystem. A three-factorial grassland management experiment was established with two fertilization treatments (without and combined N, phosphorus and potassium fertilization), two mowing frequencies (cut once and thrice per year) and three sward compositions (control, monocot- and dicot-enhanced swards). We measured N losses as leaching and nitrous oxide emissions, and soil available N as gross N mineralization rates. Fertilization increased N losses due to increased nitrification and decreased microbial N immobilization, and consequently decreased NRE. Intensive mowing partly dampened high N losses following fertilization. Sward compositions influenced NRE but not N losses: control swards that developed for decades under extensive management had the highest NRE, whereas monocot-enhanced sward had the lowest NRE. NRE was highly correlated with microbial NH₄⁺ immobilization and microbial biomass and only marginally correlated with plant N uptake, underlining the importance of microbial N retention in the soil-plant system. Microbial N retention is reflected in NRE but not in indices commonly used to reflect plant response. NRE was able to capture the effects of sward composition and fertilization whereas N losses were only sensitive to fertilization; thus, NRE is a better index when evaluating environmental sustainability of sward compositions and management practices of grasslands.     

Development of a pilot scale anaerobic digester for biogas production from cow manure and whey mix

This paper presents results from anaerobic digestion of cow manure and whey mix. A pilot scale anaerobic digester, 128 l in volume, has been developed, to operate under batch and fed-batch conditions. The versatile and unique characteristics of the instrument allowed testing the methane production directly in the farm. The digester performance was evaluated with two calibration tests, the main for a period of 56 days. The study test was divided into three phases, one for each type of feeding operation (batch, fed-batch, batch). The initial phase of digestion resulted in 57 l-CH₄/kg-VS, the second phase had a yield of 86.6 l-CH₄/kg-VS and the third one had a production of 67 l-CH₄/kg-VS. The total methane yield was equal to 211.4 l-CH₄/kg-VS. Using the obtained pilot plant results to a real scale diary production cycle, it was possible to evaluate an electricity production equal to 8.86 kwh per 1 t/d. The conducted tests did show that there is a good potential to the use of a cow manure and whey biomass mix for biogas production.     

Runoff transport of faecal coliforms and phosphorus released from manure in grass buffer conditions

AIMS: To test the hypothesis that faecal coliform (FC) and phosphorus (P) are transported similarly in surface runoff through the vegetative filter strip after being released from land-applied manure. METHODS AND RESULTS: The Hagerstown soil was packed into boxes that were 10 cm deep, 30 cm wide and 100, 200 or 300 cm long. Grass was grown in boxes prior experiments. Same-length boxes were placed under rainfall simulator and tilted to have with either 2% or 4% slopes. Dairy manure was broadcast on the upper 30-cm section. Rainfall was simulated and runoff samples were collected and analysed for Cl, FC and total phosphorus (TP). Mass recovery, the concentration decrease rate k, and the ratio FC : TP showed that there was a consistent relationship between FC and TP in runoff. Conclusion: The FC and TP transport through simulated vegetated buffer strips were highly correlated. SIGNIFICANCE AND IMPACT OF THE STUDY: As a knowledge base on the effect of the environmental parameters on P transport in vegetated buffer strips is substantially larger than for manure-borne bacteria, the observed similarity may enhance ability to assess the efficiency of the vegetated buffer strips in retention of FC currently used as indicator organisms for manure-borne pathogens.     

秸秆与牛粪混合发酵对秸秆降解及土壤肥力的影响

利用GET技术可以有效地降解秸秆生产清洁能源生物甲烷,达到无害化处理与利用秸秆的目的。本研究应用GET技术研究了发酵基质(秸秆∶牛粪)配比和温度对秸秆降解及土壤肥力的影响,以求为GET技术的推广与应用提供支撑。结果表明,各处理因素中发酵基质配比和温度及其相互作用对秸秆纤维素和半纤维素的降解有显著影响,两因数的交互作用对纤维素和半纤维素的降解也有显著作用,但对木质素的影响不显著。其中发酵基质配比以1∶1最为适宜,其纤维素和半纤维素的降解率分别为55. 39%和27. 75%;秸秆纤维素的降解率随着温度的升高而增加,但半纤维素降解率在30℃时达到最高,分别比10℃、20℃和40℃时高33. 80%、18. 37%和6. 26%。发酵基质配比和温度对厌氧发酵后土壤的肥力也有显著作用,土壤有机质、全氮和全磷含量均以1∶1配比处理和30℃处理条件下为最高。GET技术的应用还能显著改善土壤结构,厌氧发酵后土壤微团聚体粒径组成由小团聚体转化为大团聚体为主,土壤微团聚体分形维数显著下降。     

Soil survival of Escherichia coli O157:H7 acquired by a child from garden soil recently fertilized with cattle manure

AIMS: This investigation was conducted to determine the survival of a naturally occurring Escherichia coli O157:H7 in garden soil linked to a sporadic case of E. coli O157 infection in Minnesota. METHODS AND RESULTS: The presence and viability of E. coli O157:H7 was monitored in manure-contaminated garden soil for several weeks. Bacterial isolates were characterized using PCR and pulsed-field gel electrophoresis (PFGE). Isolates obtained from the patient and the garden plots during this investigation had indistinguishable PFGE patterns and had the same virulence factors (stx1, stx2, eaeA, ehxA). The E. coli O157:H7 levels obtained from the garden plots declined gradually for a period of 2 months, and on day 69 only one garden plot of four had detectable levels of pathogen. All plots were negative on day 92. The rate of decline in the soil samples stored at 4 degrees C was faster compared with soil samples that remained in ambient conditions, and in refrigerated storage E. coli O157:H7 could not be detected after 10 days. CONCLUSIONS: E. coli O157:H7 strains can survive on manure-amended soil for more than 2 months, and this survival could be reduced by low temperature. SIGNIFICANCE AND IMPACT OF THE STUDY: This is one of the few reports that have investigated the survival of a proven virulent strain in naturally contaminated soil samples. This case stresses the importance of avoiding the use of raw cattle manure to amend soil for cultivation of foods, including soils in residential garden plots.     

Removal of nitrate and phosphorus from hydroponic wastewater using a hybrid denitrification filter (HDF)

A laboratory-scale hybrid-denitrification filter (HDF) was designed by combining a plant material digester and a denitrification filter into a single unit for the removal of nitrate and phosphorus from glasshouse hydroponic wastewater. The carbon to nitrate (C:N) ratio for efficient operation of the HDF was calculated to be 1.93:1 and the COD/BOD₅ ratio was 1.2:1. When the HDF was continuously operated with the plant material replaced every 2 days and 100% internal recirculation of the effluent, a high level of nitrate removal (320–5 mg N/L, >95% removal) combined with a low effluent sBOD₅ concentration (<5 mg/L) was consistently achieved. Moreover, phosphate concentrations in the effluent were maintained below 7.5 mg P/L (>81% reduction). This study demonstrates the potential to combine a digester and a denitrification filter in a single unit to efficiently remove nitrate and phosphate from hydroponic wastewater in a single unit.