Combined pollution of arsenic and Polymyxin B enhanced arsenic toxicity and enriched ARG abundance in soil and earthworm gut microbiotas

Polymyxin B (PMB) is considered as the last line of antibiotic defense available to humans. The environmental effects of the combined pollution with PMB and heavy metals and their interaction mechanisms are unclear. We explored the effects of the combined pollution with PMB and arsenic (As) on the microbial composition of the soil and in the earthworm gut, as well as the spread and transmission of antibiotic resistance genes (ARGs). The results showed that, compared with As alone, the combined addition of PMB and As could significantly increase the bioaccumulation factor and toxicity of As in earthworm tissues by 12.1% and 16.0%, respectively. PMB treatment could significantly increase the abundance of Actinobacteria in the earthworm gut (from 35.6% to 45.2%), and As stress could significantly increase the abundance of Proteobacteria (from 19.8% to 56.9%). PMB and As stress both could significantly increase the abundance of ARGs and mobile genetic elements (MGEs), which were positively correlated, indicating that ARGs might be horizontally transferred. The inactivation of antibiotics was the main resistance mechanism that microbes use to resist PMB and As stress. Network analysis showed that PMB and As might have antagonistic effects through competition with multi-drug resistant ARGs. The combined pollution by PMB and As significantly promoted the relative abundance of microbes carrying multi-drug resistant ARGs and MGEs, thereby increasing the risk of transmission of ARGs. This research advances the understanding of the interaction mechanism between antibiotics and heavy metals and provides new theoretical guidance for the environmental risk assessment and combined pollution management.     

电子废弃物中的废塑料热解特性研究

选取电脑电路板上三种典型电子元器件(并行通信口、插槽、电路板)中的废塑料,研究不同的升温速率和成分对样品热解的特性影响及其动力学分析。在氮气气氛下进行热解实验,温度从室温升到1000℃,升温速率分别设为10,20℃/min。研究结果表明,并行通信口、插槽和电路板中塑料的失重有相似的变化趋势,且随着升温速率的变化,达到最高热解速率时所对应的温度也发生变化,其中电路板中塑料的失重率最小,并行通信口中塑料的失重率最大。热解速率随着升温速率的提高而增大,在不同的升温速率下,同一样品的热解剩余物质量分数基本一致。电路板中塑料的含碳量高于并行通信口和插槽中的塑料含碳量,并通过动力学研究得出电路板中塑料的活化能最小。     

PVA降解酶催化反应的动力学方程

(上接2012年第6期第255页)结合图2发现,混合菌系产生的PVA降解酶在PVA浓度4 g/L以下时显示出一级反应特征。即,当底物浓度低时,酶的活性中心未被饱和,反应速度随底物浓度上升而成正比关系。因此,底物浓度越大,酶反应速率越快,PVA降解酶酶活越大。利用双倒数作图法求解该PVA降解酶酶催化的米氏方程。将图2中的PVA浓度([S])和PVA降解酶酶活(酶催化反应速率V)化为对应的1/[S]和1/V(见表2)。     

基于清单分析的农业面源污染源强计算方法

为了计算农业面源污染的源强,基于清单分析的思想,建立了农业面源污染清单分析表、农业面源污染源强的计算公式及其影响参数值的确定方法,最终形成了农业面源污染源强计算的清单分析方法体系。采用士述方法,对江苏省常熟市农业面源污染源强的计算进行了实例研究,表明该方法是可行的。     

Biogenic C-doped titania templated by cyanobacteria for visible-light photocatalytic degradation of Rhodamine B

Cyanobacteria, which occurred in eutrophic water harvest solar light to carry out photosynthesis with high efficiency. In this work, cyanobacteria （Microcystis sp.） were used as biotemplate to synthesize titania structure. The synthesized titania sample had similar morphology to that of the original template in spite of the fragile unicellular structures and extremely high water content of cyanobacterial cells. Incorporation of biogenic C, as well as the morphology inherited from biotemplate improved visible- light absorbance of the titania structure. The sample exhibited higher visible-light photocatalytic activity than commercial titania photocatalyst Degussa P25 for Rhodamine B （RhB） degradation. Compared with those C-doped titania photocatalysts prepared by other methods, cyanobacteria templated titania photocatalyst offer some potential for competitive advantages. The reported strategy opened up a new use for the cyanobacteria. It could also be used for titania in applications such as treatment of polluted water, dye-sensitized solar cells, or other regions.     

双道HG—AFS同时测定鲤鱼肝脏中痕量Hg和As

应用氢化物原子荧光法,测定鲤鱼肝脏中痕量Hg和As,该法具有原子吸收和原子发射光谱两种技术优势,同时它具有分析灵敏度高,干扰少,线性范围宽,可多元素同时测定等优点;在KBH4-酸还原体系中同时测定鱼肝中Hg和As,方法检出限分别为Hg：0．33ng／ml和As0．36ng／ml,线性范围分别为：0.1—2.0ng／ml和1．0—20．0ng／ml。加标回收率分别为Hg：96．0％和As：100．6％。分析结果可靠,方法令人满意,并适合大批量样品的分析.     

Implications of Upstream Flow Availability for Watershed Surface Water Supply across the Conterminous United States

Although it is well established that the availability of upstream flow (AUF) affects downstream water supply, its significance has not been rigorously categorized and quantified at fine resolutions. This study aims to fill this gap by providing a nationwide inventory of AUF and local water resource, and assessing their roles in securing water supply across the 2,099 8‐digit hydrologic unit code watersheds in the conterminous United States (CONUS). We investigated the effects of river hydraulic connectivity, climate variability, and water withdrawal, and consumption on water availability and water stress (ratio of demand to supply) in the past three decades (i.e., 1981–2010). The results show that 12% of the CONUS land relied on AUF for adequate freshwater supply, while local water alone was sufficient to meet the demand in another 74% of the area. The remaining 14% highly stressed area was mostly found in headwater areas or watersheds that were isolated from other basins, where stress levels were more sensitive to climate variability. Although the constantly changing water demand was the primary cause of escalating/diminishing stress, AUF variation could be an important driver in the arid south and southwest. This research contributes to better understanding of the significance of upstream–downstream water nexus in regional water availability, and this becomes more crucial under a changing climate and with intensified human activities.     

加氢装置高压串低压风险分析及对策

针对加氢装置高压串低压的特点,分析讨论了其存在的火灾、爆炸、人身伤害、中毒等风险,针对这些风险提出对应的安全防范措施。     

Characterization of VOC emissions from construction machinery and river ships in the Pearl River Delta of China

Speciated characterization of Volatile Organic Compounds (VOCs),including oxygenated VOCs (OVOCs),from construction machinery and river ships in China is currently lacking.In this regard,we conducted field measurement on speciated VOC (including OVOC) emissions from six construction machinery and five river ships in the Pearl River Delta (PRD) region to identify VOC emission characteristics.We noticed that OVOC emissions from construction machinery and ships accounted for more than 50%of the tot...     

中国排污许可证制度执行现状调查

本研究以广州、石家庄、兰州、哈尔滨和大同5个城市为调研对象,收集各城市20年来许可证相关的法规制度,并与各城市环境保护监管部门负责人及典型企业环保专职人员进行了访谈。研究表明,中国排污许可证制度在提高企业环保守法意识和推动总量减排上起到了明显作用,但也面临着法律体系不完善,行政资源不足、排放量核算方法不明确、处罚力度弱以及公众参与不充分等问题。在此基础上,本研究提出中国排污许可证制度的改进建议,为决策部门制定相应的政策提供科学和技术的支撑。