Veterinary drugs in groundwater in a dairy region of central Argentina and risk assessment for human health

Veterinary drugs used in dairy production are potential contaminants of surface or groundwater sources, being able to affect human and environmental health. It is known that chronic exposure to antibiotics in low concentrations present in water can generate microbial resistance. This study aimed to evaluate the presence of veterinary drugs in 53 groundwater samples used for animal and human consumption, collected in dairy milking parlors, in an important milk-producing area of central Argentina, and to assess the risk to human health when they are used as drinking water. In 75% of the total samples analyzed, at least one veterinary drug was detected. The most frequently found drugs in water samples were the antibiotics tetracycline in 58.5% and oxytetracycline in 56.6%, and an anti-inflammatory, flunixin in 39.6%. In the water samples, the tetracycline and oxytetracycline concentrations were between 0.1 and 5.3 μg/L and flunixin concentrations were between 0.01 and 2.1 μg/L. The frequency of appearance and the concentration levels of the substances found in the water samples were evaluated according to the productivity, size, and production system (confined or pasture) of the dairy farms. Higher concentrations and proportions of water samples containing antibiotics were observed when the number of animals per dairy farm was >182 and when the productivity was high (>25 liters per animal per day). In the case of flunixin, the percentage of detection was similar in all evaluated categories. The risk assessment for children and adults, considering the intake of drinking water containing residues of these drugs, did not indicate a significant health risk. It would be advisable to evaluate other sources of drinking water, both surface and underground, in other regions of the country, to provide data to assess the impact of these substances and the other contaminants on environmental and human health.     

Influence of hydraulic retention time on behavior of antibiotics and antibiotic resistance genes in aerobic granular reactor treating biogas slurry

Longer HRT can enhance degradation rate of sulfamethoxazole in granular reactor. Longer HRT can reduce accumulated concentrations of TCs and QNs in sludge. Longer HRT may have increased relative abundances of ARGs in aerobic granules. The behavior of antibiotics and the corresponding resistance genes in aerobic granular reactors for treating biogas slurry under different hydraulic retention times (10.7 h, R1; 8 h, R2) was investigated in this study. The results indicated that the hydraulic retention time could affect the effluent concentrations and removal efficiencies of sulfonamides. The average removal rates of tetracyclines, fluoroquinolones, and sulfonamides were 63%, 46%, and 90% in R1, and 62%, 46%, and 86% in R2, respectively. Although the removal efficiencies of tetracyclines and fluoroquinolones were similar in both reactors, the respective accumulated concentrations of tetracyclines and fluoroquinolones in R1 were 7.00 and 11.15 µg/g SS, which were lower than those in R2 (8.92 and 13.37 µg/g SS, respectively). The difference in the relative abundance of target antibiotic resistance genes between both reactors was not significant, yet the average relative abundances of all target resistance genes in R1 were higher than those in R2 after 45 days of operation. The results of this study suggested that a longer hydraulic retention time could enhance the antibiotic removal ability of aerobic granular sludge, yet it may also increase the risk of surplus sludge utilization from a resistance genes point of view.     

Estimating population dynamics without population data

We develop a biologically correct cost system for production systems facing invasive pests that allows the estimation of population dynamics without a priori knowledge of their true values. We apply that model to a data set for olive producers in Crete and derive from it predictions about the underlying population dynamics. Those dynamics are compared to information on population dynamics obtained from pest sampling with extremely favorable results.     

Who should wear mask against airborne infections? Altering the contact network for controlling the spread of contagious diseases

There are several ways of controlling the propagation of a contagious disease. For instance, to reduce the spreading of an airborne infection, individuals can be encouraged to remain in their homes and/or to wear face masks outside their domiciles. However, when a limited amount of masks is available, who should use them: the susceptible subjects, the infective persons or both populations? Here we employ susceptible-infective-recovered (SIR) models described in terms of ordinary differential equations and probabilistic cellular automata in order to investigate how the deletion of links in the random complex network representing the social contacts among individuals affects the dynamics of a contagious disease. The inspiration for this study comes from recent discussions about the impact of measures usually recommended by health public organizations for preventing the propagation of the swine influenza A (H1N1) virus. Our answer to this question can be valid for other eco-epidemiological systems.     

Residual veterinary antibiotics in swine manure from concentrated animal feeding operations in Shandong Province, China

The scientific interest in the occurrence and fate of antibiotics in animal husbandry has increased during the past decades because of the emergence and development of antimicrobial resistance in pathogenic bacteria. This study developed a method for simultaneous detection of five sulfonamides, three tetracyclines and one macrolide in swine manure with stable recoveries (73.0-110.6%) and high sensitivity (limit of quantification <90 μg kg⁻¹). Thereafter, a total of 126 swine manure samples, collected from 21 concentrated animal feeding operations (CAFOs) in Shandong Province of China during summer and winter, were analyzed. The potential influences of different sampling seasons, swine types and food sources on residual antibiotic concentrations were examined in detail. The maximum concentration of residual antibiotic could reach up to 764.4 mg kg⁻¹ (chlortetracycline), and the detection frequencies were 84.9-96.8% for tetracyclines, 0.8-51.6% for sulfonamides and 4.8% for macrolide. These data reveal that antibiotics were extensively used in CAFOs in this district and the manure may act as a non-specific source of antibiotic residue in farmlands and aquatic environments.     

Selected dark sides of biomass-derived biochars as environmental amendments

With the rapid increase in the application of biochars as amendments, studies are needed to clarify the possible environmental risks derived from biochars to use safely the biomass resources. This work reported selected dark sides of maize straw-and swine manurederived biochars pyrolyzed at 300 and 500°C. During the pyrolysis processes, total heavy metals in the biochars were enriched greatly accompanying with considerable emission of the heavy metals into atmosphere and the trends became increasingly obvious with pyrolysis temperature. Meanwhile, the biochars showed distinctly decreased available heavy metals compared with raw feedstocks, which could be mainly attributed to the sorption by the inorganics in the biochars. The water-and acid-washing treatments significantly increased the releasing risks of heavy metals from biochars into the environments. Electron paramagnetic resonance analysis indicated that persistent free radicals, emerged strongly in the biochars as a function of the aromatization of biomass feedstocks, were free from the influence of water-, acid-, or organic-washing of the biochars and could remain stable even after aged in soils for 30 days. Dissolved biochars, highly produced during pyrolysis processes, showed distinct properties including lower molecular weight distribution while higher aromaticity compared with soil dissolved organic carbon.The results of this study provide important perspectives on the safe usage of biochars as agricultural/environmental amendments.     

Adoption of Stream Fencing Among Dairy Farmers in Four New Zealand Catchments

The effect of dairy farming on water quality in New Zealand streams has been identified as an important environmental issue. Stream fencing, to keep cattle out of streams, is seen as a way to improve water quality. Fencing ensures that cattle cannot defecate in the stream, prevents bank erosion, and protects the aquatic habitat. Stream fencing targets have been set by the dairy industry. In this paper the results of a study to identify the factors influencing dairy farmers' decisions to adopt stream fencing are outlined. Qualitative methods were used to gather data from 30 dairy farmers in four New Zealand catchments. Results suggest that farm contextual factors influenced farmers' decision making when considering stream fencing. Farmers were classified into four segments based on their reasons for investing in stream fencing. These reasons were fencing boundaries, fencing for stock control, fencing to protect animal health, and fencing because of pressure to conform to local government guidelines or industry codes of practice. This suggests that adoption may be slow in the absence of on-farm benefits, that promotion of stream fencing needs to be strongly linked to on-farm benefits, and that regulation could play a role in ensuring greater adoption of stream fencing.     

Effects of duckweed (Spriodela polyrrhiza) remediation on the composition of dissolved organic matter in effluent of scale pig farms

The swine effluent studied was collected from scale pig farms, located in Yujiang County of Jiangxi Province, China, and duckweed (Spriodela polyrrhiza) was selected to dispose the effluent. The purpose of this study was to elucidate the effects of duckweed growth on the dissolved organic matter composition in swine effluent. Throughout the experiment period, the concentrations of organic matter were determined regularly, and the excitation–emission matrix (3DEEM) spectroscopy was used to characterize the fluorescence component. Compared with no-duckweed treatments (controls), the specific ultra-violet absorbance at 254 nm (SUVA₂₅₄) was increased by a final average of 34.4% as the phytoremediation using duckweed, and the removal rate of DOC was increased by a final average of 28.0%. In swine effluent, four fluorescence components were identified, including two protein-like (tryptophan, tyrosine) and two humic-like (fulvic acids, humic acids) components. For all treatments, the concentrations of protein-like components decreased by a final average of 69.0%. As the growth of duckweed, the concentrations of humic-like components were increased by a final average of 123.5% than controls. Significant and positive correlations were observed between SUVA₂₅₄ and humic-like components. Compared with the controls, the humification index (HIX) increased by a final average of 9.0% for duckweed treatments. Meanwhile, the duckweed growth leaded to a lower biological index (BIX) and a higher proportion of microbial-derived fulvic acids than controls. In conclusion, the duckweed remediation not only enhanced the removal rate of organic matter in swine effluent, but also increased the percent of humic substances.     

畜禽养殖行业废水排放标准的研究

讨论了畜禽养殖行业的排放污水、粪渣及恶臭的污染状况;综合国内外对畜禽场排放污水所采用的治理技术、达到的各项指标及中国目前的经济状况、技术条件,提出畜禽养殖行业排放污水的生化指标上限值,COD_(Cr)、BOD_5、SS、KN、TP分别为200、80、150、20、2.0mg/L,pH为6.5～9.0;卫生指数的粪大肠菌群数少于10~4个/L,蛔虫卵标准值为少于2个/L,粪渣经无害化处理后,蛔虫卵死亡率>95％;恶臭标准按感官作用阀值,采用国家2级标准。     

CFD simulation of pool fires situated at differing elevation

When two or more pool fires happen to burn so close to each other that they interact, they are termed ‘multiple pool fires’ (MPF). Past accident analysis reveals that MPFs occur quite frequently in chemical process industries. Controlled experiments done so far to study MPFs have indicated that MPFs lead to increase in the fuel burning rate, flame height and heat release rate (HRR) but the nature and the extent of the impacts of different factors on these manifestations is as yet poorly understood. In this context computational fluid dynamics (CFD) appears to be a tool which can enable more detailed and realistic simulation of MPFs than other possible approaches, especially due to its ability to closely approximate the underlying physical phenomena. In tank farms there are situations where different storage tanks are placed at different elevations yet close to each other. If such tanks happen to catch fire, the resulting fires may influence each other in a manner that may be a function of the difference in the tanks’ elevation. However no CFD study has been carried out which addresses this type of situation. Hence an attempt has been made to employ CFD to study MPFs involving two pools with fuel surfaces are at different elevations. Results reveal that good correlation is possible between the experimental findings and the CFD simulations.