藻渣添加对玉米秸秆厌氧发酵特征的影响

厌氧发酵是农业废弃物资源化的有效途径之一.将农业废弃物同其他富含氮元素的有机废物混合发酵能够有效地提高产气效率.以玉米秸秆为例,尝试利用藻渣作为添加剂,提高农业废弃物厌氧发酵的性能.实验主要研究了混合发酵比例对沼气产量、甲烷产量、沼渣沼液特征的影响.当玉米秸秆、藻渣和接种污泥的挥发性固体质量分数为10∶ 2∶2时,沼气产率最高可达421.0 mL/g,甲烷产率为218.7 mL/g.沼渣组分分析表明,纤维素和半纤维素降解效率分别为83.7％和68.4％,和对照相比纤维素的降解效率显著提高.结果表明,藻渣的添加能够有效地促进玉米秸秆厌氧发酵产甲烷过程.     

我国辐射环境监测法规体系研究

通过对我国辐射环境监测相关法规的调研,在深入分析当前辐射环境监测法规框架结构和突出问题的基础上,构建我国辐射环境监测法规体系,重点关注辐射环境质量监测、核与辐射监督性监测及应急监测等方面的工作需求,提出完善部门规章、健全核安全导则及规范性文件的建议。     

不同好氧预处理方式对餐厨垃圾产甲烷的影响

为了研究不同好氧预处理方式对餐厨垃圾厌氧消化产甲烷的影响,通过建立3个模拟厌氧生物反应器,研究了传统厌氧生物反应器C1、上层好氧预处理-厌氧生物反应器C2和底部好氧预处理-厌氧生物反应器C3 3种不同操作条件下的产甲烷过程.结果表明,挥发性有机酸的累积使C1始终处于产甲烷滞后阶段;而C2、C3的好氧预处理通过加快易水解酸化组分和过量挥发性有机酸的好氧降解,有效缓解了酸性抑制,产甲烷滞后时间明显缩短至10 d内.第32天C2停止上层曝气后,在27 d内甲烷浓度达到了50％以上,同时,产甲烷速率迅速上升,并在第81天可达到峰值773 mL/(kg·d).C3在第11天停止底部曝气后,虽然经过22 d的时间甲烷浓度即上升至50％,但之后产甲烷速率经历回落阶段后再次逐渐上升,在实验结束时仅达到517 mL/(kg·d).上层曝气的好氧预处理方式所需曝气时间相对较长,但其产甲烷启动快,与底部曝气相比,其后期的甲烷化过程更稳定并可达到较高的产甲烷速率.     

Determination of the residue dynamics and dietary risk of thiamethoxam and its metabolite clothianidin in citrus and soil by LC-MS/MS

A modified quick, easy, cheap, effective, rugged and safe (QuEChERS) method was developed for the determination of thiamethoxam and its metabolite clothianidin in citrus (including the whole citrus, peel and pulp) and soil samples by liquid chromatography-tandem mass spectrometry. The sample was extracted with acetonitrile and purified with octadecylsilane. The detection limits of both compounds were 0.0001–0.0002?mg kg^–1, while the limit of quantification of thiamethoxam was 0.002?mg kg^–1 and the limit of quantitation of metabolites was 0.001?mg kg^–1. The recovery was 70.37%–109.76%, with inter-day relative standard deviations (RSD) (n?=?15) values ≤9.46% for the two compounds in the four matrices. The degradation curve of thiamethoxam in whole citrus and soil was plotted using the first-order kinetic model. The half-life of the whole citrus was 1.9–6.2?days, and the half-life of the soil was 3.9–4.2?days. The terminal residue of thiamethoxam (the sum of thiamethoxam and clothianidin, expressed as thiamethoxam) was found to be concentrated on the peel. The final residual amount of thiamethoxam in the edible portion (pulp) was less than 0.061?mg kg^–1. The risk quotient values were all below 1, indicating that thiamethoxam as a citrus insecticide does not pose a health risk to humans at the recommended dosage.     

基于统计方法的辽东湾沉积物中多环芳烃来源特征分析

为研究辽东湾表层沉积物中多环芳烃(PAHs)的来源特征,2014年5月采集了20个辽东湾海域表层沉积物样品,并利用气相色谱质谱联用仪对优先控制的16种PAHs进行测定,采用聚类分析、主成分分析-多元线性回归分析、异构体比值3种统计方法对辽东湾表层沉积物中PAHs来源特征进行了研究。结果表明,辽东湾表层沉积物中PAHs含量范围88.5~199.3 ng·g-1,平均值为(126.3±35.3)ng·g-1,其中,萘、菲和荧蒽是PAHs优势组分。通过统计分析结果表明,辽东湾北部表层沉积物中PAHs含量低于西南部,沉积物中PAHs的来源包括石油燃烧来源、煤炭、木材等生物质燃烧来源和石油来源,其中燃烧来源是主要来源,煤炭、木材等生物质燃烧来源占49.9%,石油燃烧来源和石油来源占50.1%。     

Removal of arsenic(III,V) by a granular Mn-oxide-doped Al oxide adsorbent: surface characterization and performance

In order to remove arsenic (As) from contaminated water, granular Mn-oxide-doped Al oxide (GMAO) was fabricated using the compression method with the addition of organic binder. The analysis results of XRD, SEM, and BET indicated that GMAO was microporous with a large specific surface area of 54.26 m^2/g, and it was formed through the aggregation of massive Al/Mn oxide nanoparticles with an amorphous pattern. EDX, mapping, FTIR, and XPS results showed the uniform distribution of Al/Mn elements and numerous hydroxyl groups on the adsorbent surface. Compression tests indicated a satisfactory mechanical strength of GMAO. Batch adsorption results showed that As(V) adsorption achieved equilibrium faster than As(III), whereas the maximum adsorption capacity of As(III) estimated from the Langmuir isotherm at 25 °C (48.52 mg/g) was greater than that of As(V) (37.94 mg/g). The As removal efficiency could be maintained in a wide pH range of 3~8. The presence of phosphate posed a significant adverse effect on As adsorption due to the competition mechanisms. In contrast, Ca²⁺ and Mg²⁺ could favor As adsorption via cation-bridge involvement. A regeneration method was developed by using sodium hydroxide solution for As elution from saturated adsorbents, which permitted GMAO to keep over 75% of its As adsorption capacity even after five adsorption–regeneration cycles. Column experiments showed that the breakthrough volumes for the treatment of As(III)-spiked and As(V)-spiked water (As concentration = 100 μg/L) were 2224 and 1952, respectively. Overall, GMAO is a potential adsorbent for effectively removing As from As-contaminated groundwater in filter application.

     

Individual and combined inhibition of phenol and thiocyanate on microbial activity of partial nitritation

This study evaluated the individual and interactive effect of phenol and thiocyanate (SCN⁻) on partial nitritation (PN) activity using batch test and response surface methodology. The IC₅₀ of phenol and SCN⁻ on PN sludge were 5.6 and 351 mg L⁻¹, respectively. The PN sludge was insensitive to phenol and SCN⁻ at levels lower than 1.77 and 43.3 mg L⁻¹, respectively. A regression model equation was developed and validated to predict the relative specific respiration rate (RSRR) of PN sludge exposed to different phenol and SCN⁻ concentrations. In the range of independent variables, the most severe inhibition was observed with a valley value (17%) for RSRR, when the phenol and SCN⁻ concentrations were 4.08 and 198 mg L⁻¹, respectively. An isobole plot was used to judge the combined toxicity of phenol and SCN⁻, and the joint inhibitory effect was variable depending on the composition and concentration of the toxic components. Furthermore, the toxic compounds showed independent effects, which is the most common type of combined toxicity.

     

应用底栖动物为指示生物的松花江干流水生态预警研究

指示生物监测及水生态预警是利用水环境中指示物种的数量、群落结构指标和个体生理指标等描述水生态系统的健康状态,其相比于常规理化监测和预警更直接地反映水体的生态质量。本研究在松花江干流2012—2015年大型底栖无脊椎动物监测结果的基础上,结合各监测点生态质量管理目标,通过分析物种的种类、出现的频次、物种污染敏感性(耐污值),尝试提出了松花江干流监控断面以底栖动物为指示生物的水生态预警模式,研究思路和结果对流域水环境风险管理指标的拓展有积极作用。     

Measurement of public awareness of climate change in China: based on a national survey with 4,025 samples

Just before the new round of UN climate change conference in Bonn, a survey report, named as the Climate Change in the Chinese Mind 2017, was released in Beijing. The investigation was conducted in the form of a computer-assisted telephone survey with a sample size of 4,025 samples, covering 332 prefecture-level administrative units and four municipalities in China. Urban-rural proportion and sex proportion were specially taken into account, so as to demonstrate the Chinese public awareness objectively. The investigation measures the public awareness from six aspects, which includes climate change beliefs, impacts, response, policies, actions, and the assessment of the effectiveness of climate communication. This article presents the key findings of the survey and provides further insights behind the data.