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71.
Anyun Zhang Zunfang Tu Junrui Shui Jinxin Liu Hongmei Tuo Haoyu Zhang Cong Lin Jingyi Feng Yuxuan Feng Wen Su 《环境科学学报(英文版)》2023,35(2):462-471
Plasmids play a critical role in the dissemination of antimicrobial resistance genes (ARGs), however, a systematical understanding of ARGs originated from plasmids in swine production is currently lacking. Herein, quantitative polymerase chain reaction was applied to determine the prevalence of ten ARGs and the class1 integron gene intI1 of plasmid source in swine manure from 44 farms in Sichuan, Hubei and Hebei provinces, China. All assayed ARGs were observed in plasmid DNA samples, and the average absolute abundance of aac(6’)-Ib-cr, blaNDM, blaCTX-M, optrA, ermB, floR, mcr-1, qnrS, tetM, sul1 and intI1 were 7.09, 2.90, 4.67, 6.62, 7.55, 7.14, 4.08, 4.85, 7.16, 7.11 and 8.07 of 10 log copies/gram, respectively. IntI1 showed a high correlation (r > 0.8, P < 0.01) with the abundance of aac(6’)-Ib-cr and sul1 in swine manure. Moreover, the farm scale (i.e., herd population) and geographical location were not found to be critical factors influencing the absolute abundance of ARGs of plasmid DNA in swine farms. However, the concentrations of florfenicol, Cu, Zn, Fe, total phosphorus (TP) and total potassium (TK) demonstrated a significant correlation with the abundance of several ARGs. Particularly, Cu and Zn had high correlations with optrA and blaCTX-M, respectively. Our results demonstrated that antibiotics, heavy metals and environmental nutrients are likely jointly contributing to the long-term persistence of ARGs in swine production. This study provides insights into the abundance and influencing factors of ARGs from swine manure, which is of significance for assessing and reducing the public health risks in livestock production. 相似文献
72.
Sorption of tylosin and sulfamethazine on solid humic acid 总被引:3,自引:0,他引:3
Tylosin(TYL) and sulfamethazine(SMT) are ionizable and polar antimicrobial compounds,which have seeped into the environment in substantial amounts via fertilizing land with manure or sewage. Sorption of TYL and SMT onto humic acid(HA) may affect their environmental fate. In this study, the sorption of TYL and SMT on HA at different conditions(pH, ionic strength) was investigated. All sorption isotherms fitted well to the Henry and Freundlich models and they were highly nonlinear with values of n between 0.5 and 0.8, which suggested that the HA had high heterogeneity. The sorption of TYL and SMT on HA decreased with increasing p H(2.0–7.5), implying that the primary sorption mechanism could be due to cation exchange interactions between TYL~+/SMT~+ species and the functional groups of HA.Increasing ionic strength resulted in a considerable reduction in the K_d values of TYL and SMT,hinting that interactions between H bonds and π–π EDA might be an important factor in the sorption of TYL and SMT on HA. Results of Fourier transform infrared(FT-IR) and ~13C-nuclear magnetic resonance(NMR) analysis further demonstrated that carboxyl groups and O-alkyl structures in the HA could interact with TYL and SMT via ionic interactions and H bonds,respectively. Overall, this work gives new insights into the mechanisms of sorption of TYL and SMT on HA and hence aids us in assessing the environmental risk of TYL and SMT under diverse conditions. 相似文献
73.
Caio Cesar de Araujo Barbosa John Dearing Sylvia Szabo Sarwar Hossain Nguyen Thanh Binh Dang Kieu Nhan Zoe Matthews 《Sustainability Science》2016,11(4):555-574
Policy-making in social-ecological systems increasingly looks to iterative, evolutionary approaches that can address the inherent complexity of interactions between human wellbeing, provision of goods, and the maintenance of ecosystem services. Here, we show how the analysis of available time-series in tropical delta regions over past decades can provide important insight into the social-ecological system dynamics in deltaic regions. The paper provides an exploratory analysis of the recent changes that have occurred in the major elements of three tropical deltaic social-ecological systems, such as demography, economy, health, climate, food, and water. Time-series data from official statistics, monitoring programmes, and Earth observation data are analysed to explore possible trends, slow and fast variables, and observed drivers of change in the Amazon, Ganges–Brahmaputra–Meghna and Mekong deltas. In the Ganges–Brahmaputra–Meghna delta zone, increasing gross domestic product and per capita income levels since the 1980s mirror rising levels of food and inland fish production. In contrast, non-food ecosystem services, such as water availability, water quality, and land stability appear to be deteriorating. In the Amazon delta, natural and anthropogenic perturbations are continuously degrading key ecosystem services, such as carbon storage in biomass and soils, the regulation of water balance, and the modulation of regional climate patterns. In the Mekong delta, rapid economic development, changing land-use practices, and salinity intrusion are progressively putting more pressure on the delivery of important provisioning services, such as rice and inland aquaculture production, which are key sources of staple food, farm incomes, and export revenue. Observed changes in many key indicators of ecosystem services point to a changing dynamic state and increased probability of systemic threshold transformations in the near future. 相似文献
74.
75.
以柚子皮为原料,采用次氯酸钠废液活化法制备了柚子皮活性炭,通过正交实验优化了制备条件,并运用SEM、FTIR和XRD技术对活性炭产品进行了表征。实验结果表明:制备柚子皮活性炭的最佳工艺条件为炭化温度350℃、次氯酸钠废液含量25%(φ)、次氯酸钠废液活化时间25 min、高温活化温度650℃、高温活化时间60 min;最佳条件下,柚子皮活性炭的产率为31.88%、碘吸附值为854 mg/g、亚甲基蓝吸附值为216.9 mg/g。表征结果显示:活化后的柚子皮炭具有更大的孔体积、更有序的孔径排布和更发达的孔隙结构;柚子皮活性炭表面存在大量的含氧基团;柚子皮活性炭的石墨化度为61.32%,具有较高的稳定性。 相似文献
76.
在两点进水的条件下采用A2/O工艺处理化工园区废水厌氧水解出水,分析配水比对A2/O工艺处理效果的影响,以及在最优配水条件下,各类A2/O工艺处理废水的实际效果。结果表明,在厌氧段-缺氧段的配水比为30%~70%时,A2/O工艺的处理效果最好。在两点进水条件下的各类A2/O工艺中,倒置A2/O和改良A2/O比常规A2/O工艺具有更好的废水处理效果。 相似文献
77.
曝气对生物促生剂修复城市黑臭河道水体的影响 总被引:3,自引:0,他引:3
在实验室条件下研究了曝气对生物促生剂修复城市黑臭河道水体效果的影响,并通过控制曝气时间及强度考察处理效果以确定曝气方式和曝气量。结果表明:在生物促生剂修复城市河道黑臭水体过程中使用曝气协同作用可大大增强生物促生剂的修复作用,加快修复速度。使用间歇曝气协同生物促生剂作用时效果与连续曝气相近,且可以降低运行成本。实验60d后,上覆水COD、NH3-N和TP去除率分别达46.8%、98.7%和73.3%,上覆水pH由7.61提高至7.92;底泥削减达5.49cm,底泥有机质削减率达10.5%。 相似文献
78.
毛乌素沙漠东部边缘中β尺度暴雨和冰雹综合分析 总被引:2,自引:1,他引:1
利用多普勒雷达资料、Micaps系统提供的常规观测资料和物理量场,对2006年9月20日发生在毛乌素沙漠东部边缘的一次强对流天气过程进行了分析。结果表明:冰雹和暴雨是由两块呈块状的中β尺度强对流单体造成的;地面能量比中α尺度"Ω"系统的生成,为能量的积聚和集中释放提供了有利条件;地面能量比中β尺度能量比低值舌的生成,为强对流天气的发生提供了抬升触发机制;冰雹和暴雨发生前,涡度场和散度场的耦合、影响雹暴区次级环流的形成,为雹暴的发生维持提供了动力机制;850 hPa等压面上湿正压场和湿斜压场的配合、以及湿位涡的三维空间结构,对雹暴的发生及落区有指示意义;在多普勒雷达径向速度场上,雹暴运动的前方对流层低层有中气旋生成,雹暴运动的后方对流层低层有中反气旋生成,而对流层中高层有辐散生成,且超级单体特征明显。 相似文献
79.
Pt and Pd in sediments from the Pearl River Estuary,South China: background levels,distribution, and source 总被引:1,自引:0,他引:1
Zhong LF Yan W Li J Tu XL Liu BM Xia Z 《Environmental science and pollution research international》2012,19(4):1305-1314
Purpose
This study assessed the concentrations of platinum (Pt) and palladium (Pd) in surface sediments and sedimentary cores collected from the Pearl River Estuary with a view of evaluating the distribution, background levels, possible sources, and contamination level of anthropogenic Pt and Pd. 相似文献80.