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

Environmental Science and Pollution Research - The increasing emergence of antibiotic-resistant genes (ARGs) represents a global threat to human health. Land application of animal manure is known...     

Optimising yield and resource utilisation of summer maize under the conditions of increasing density and reducing nitrogen fertilization

The inefficient use of resources always poses risks of maize (Zea mays L.) yield reduction in China. We performed this research to monitor the effects of increasing plant density and reducing nitrogen (N) rate on radiation-use efficiency (RUE), N efficiency traits, grain yield (GY) and their inter-relationships. Besides, whether GY and resource-use efficiency can both be maximized was examined. Hence, a 2-year field experiment was conducted using a widely grown variety “Denghai 618” in Shandong, China. Treatments contained two different plant densities [67,500 (D₁) and 97,500 (D₂) plant ha^?1] and three N levels [0 (N_?2), 180 (N_?1), 360 (N_ck) kg ha^?1], set D₁N_ck as control. Significant increases in grain yield, biomass, RUE, above-ground N uptake (AGN) and N efficiency were observed when density increased from D₁ to D₂. Declining N application was accompanied by reductions in yield, RUE and AGN especially under high density, yet an obvious improvement in N recovery efficiency (NRE), agronomic N efficiency and N partial factor productivity. The increased GY was positive related with population biomass (r = 0.895**), RUE (r = 0.769**) and AGN (r = 0.923**), whereas it has no significant correlation with N efficiency. In this study, D₂N_ck obtained 18.8, 17.9, 24.8 and 29.7% higher grain yield, RUE, AGN and NRE respectively, compared to control, optimizing both yield and the efficiencies of radiation and N use. Furthermore, higher yield and RUE with more desirable N efficiency may be possible via optimizing density and N rate combination.     

Magnetic microsphere confined ionic liquid as a novel sorbent for the determination of chlorophenols in environmental water samples by liquid chromatography

Magnetic microsphere confined ionic liquid was synthesized by covalently bonding N-methylimidazolium on magnetic microspheres. The functionalized magnetic microspheres were characterized by Fourier transform infrared (FT-IR) spectrometry, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The prepared material was used for the preconcentration of three chlorophenols (CPs) in water combined with high-performance liquid chromatography (HPLC). Several conditions that probably affected the extraction efficiency such as standing time, eluent and its volume, sample pH and volume, were optimized. Under the optimal conditions, good recoveries (70.3-88.8%) were achieved with satisfactory relative standard deviations (RSDs) of less than 6.0%. The limits of detection for the three CPs were 0.20-0.35 μg L(-1). The results indicated that the ionic liquid-functionalized magnetic microspheres show significant promise for the analysis of CPs in environmental samples.     

矿井通风阻力测定及分析

矿井通风阻力测定是煤矿安全生产的一项重要工作。基于斜沟煤矿通风阻力测定工作,对测定前的准备工作、测定方法与原理作了简要介绍,对测量数据进行了平差处理,对测定结果进行了分析。针对系统中存在的问题提出了对策措施,为今后矿井通风系统的科学管理提供可靠依据。     

Dechlorination of disinfection by-product monochloroacetic acid in drinking water by nanoscale palladized iron bimetallic particle

Nanoscale palladized iron(Pd/Fe)bimetallic particles were prepared by reductive deposition method.The particles were characterized by X-ray diffraction(XRD),X-ray fluorescence(XRF),scanning electron microscope(SEM),transmission electron microscope(TEM),and Brunauer-Emmett-Teller-nitrogen(BET-N_2)method.Data obtained from those methods indicated that nanoscale Pd/Fe bimetallic particles containedα-Fe~0.Detected Pd to Fe ratio by weight(Pd/Fe ratio)was close to theoretical value. Spherical granules with di...     

清洁生产审核在机械制造企业中的应用

清洁生产是企业实现可持续发展战略的必由之路,企业清洁生产审核是企业实施清洁生产的重要内容和有效工具。本文在对某机械制造企业进行清洁生产审核中,针对行业特点,结合企业自身情况,组织实施了3个中／高费方案和18无／低费方案,已实施方案每年可节电79．7万度,节约柴油10．1吨,节约工时费25．0万元,燃气费1．0万元,产生效益93．2万元,取得了良好的经济效益、环境效益和社会效益。     

A review of rapid transport of pesticides from sloping farmland to surface waters:Processes and mitigation strategies

Pesticides applied to sloping farmland may lead to surface water contamination through rapid transport processes as influenced by the complex topography and high spatial variability of soil properties and land use in hilly or mountainous regions. However, the fate of pesticides applied to sloping farmland has not been sufficiently elucidated. This article reviews the current understanding of pesticide transport from sloping farmland to surface water. It examines overland flow and subsurface lateral flow in areas where surface soil is underlain by impervious subsoil or rocks and tile drains. It stresses the importance of quantifying and modeling the contributions of various pathways to rapid pesticide loss at catchment and regional scales. Such models could be used in scenario studies for evaluating the effectiveness of possible mitigation strategies such as constructing vegetated strips, depressions, wetlands and drainage ditches, and implementing good agricultural practices. Field monitoring studies should also be conducted to calibrate and validate the transport models as well as biophysical-economic models, to optimize mitigation measures in areas dominated by sloping farmland.     

产表面活性剂降解石油菌株产物性质及降解性能研究

微生物是组成生态系统的重要成员,在污染物去除中发挥着重要作用,是生物修复中的主力,然而在石油污染修复过程中,石油烃的疏水性会限制微生物对石油的降解,但一些微生物的细胞代谢物即生物表面活性剂,它是微生物在一定条件下代谢分泌产生的具有一定表面活性,集亲水基和疏水基结构于一分子的两亲性化合物,可以促进油的乳化,提高油的分散程度,增大菌株和油珠的接触机会,促进对石油烃的吸收和降解。在实验室分离得到了7株产表面活性剂石油降解菌株,经分子鉴定可知菌1和菌2都为粘质沙雷氏菌Serratia marcescens,菌3为居植物柔武氏菌Raoultella planticola,菌4,菌6和菌7都为克雷伯氏菌Klebsiella variicola,菌5为蜡状芽孢杆菌Bacillus cereus。主要研究了它们的生长与表面活性剂物质分泌状况的关系,发现随着时间增加,OD值随之增大,表面张力呈现下降趋势;并对菌株产物进行提取和薄层层析,离子型分析和红外光谱分析,初步判断其产物均为阴离子糖脂类;通过pH,初始油质量浓度,接种量和盐度4个单因素的变化研究菌1粘质沙雷氏菌,菌3居植物柔武士菌,菌5蜡状芽孢杆菌和菌6克雷伯氏菌对石油类物质降解能力,发现菌3居植物柔武氏菌和菌5蜡状芽孢杆菌降解性能较好;通过响应曲面法优化蜡状芽孢杆菌的降解条件,得出其最佳降解条件为pH为5.02,油质量浓度为3 g·L-1,接种量为1199.98μL,盐度为0.5 g·L-1时,在此条件下,菌株对石油的降解率为66.94%。     

有毒气体泄漏无线报警及控制系统的设计

应用传感器和无线电技术,提出了一种有毒气体泄漏无线报警及控制系统的设计方案。该系统采用半导体气敏传感器QM-N10来检测有毒气体,通过检测电路把有毒气体浓度的变化转换为相应的电压信号,一旦超过设定的有毒气体的安全浓度值,系统启动发射电路工作。接收处理电路接收和处理发射电路发送的无线编码信号,同时输出控制信号启动扬声器报警,提醒工作人员采取安全防护措施。