火山石生物滤床对微囊藻毒素的去除

微囊藻水华爆发导致大量微囊藻毒素释放至地表水环境中,严重威胁着饮用水供水安全.通过不同条件火山石自然曝气生物滤床(活性挂膜、灭活挂膜、未挂膜和无填料滤床)对不同形态、构型(MC-LR、MC-RR)的微囊藻毒素的去除实验,探讨其去除效率、途径和机理.结果表明,火山石自然曝气生物滤床对微囊藻毒素的去除是微生物降解和基质吸附共同作用的结果.胞外毒素和胞内毒素的总去除率分别为58％和91％.其中,胞外毒素主要通过微生物降解作用途径去除,占胞外毒素总去除率的(41±4.2)％,胞内毒素则主要通过基质吸附途径去除,占胞内毒素总去除率的(64±5.1)％.生物膜吸附、光降解等其他途径无明显作用.另外,不同构型的微囊藻毒素在火山石自然曝气生物滤床中均能有效去除,MC-LR和MC-RR的去除率分别为68％和54％.     

Nitrogen regulation of the climate-carbon feedback: evidence from a long-term global change experiment

Modeling studies have shown that nitrogen (N) strongly regulates ecosystem responses and feedback to climate warming. However, it remains unclear what mechanisms underlie N regulation of ecosystem-climate interactions. To examine N regulation of ecosystem feedback to climate change, we have conducted a warming and clipping experiment since November 1999 in a tallgrass prairie of the Great Plains, USA. Infrared heaters were used to elevate soil temperature by an average of 1.96 degrees C at a depth of 2.5 cm from 2000 to 2008. Yearly biomass clipping mimicked hay or biofuel feedstock harvest. We measured carbon (C) and N concentrations, estimated their content and C:N ratio in plant, root, litter, and soil pools. Warming significantly stimulated C storage in aboveground plant, root, and litter pools by 17%, 38%, and 29%, respectively, averaged over the nine years (all P < 0.05) but did not change soil C content or N content in any pool. Plant C:N ratio and nitrogen use efficiency increased in the warmed plots compared to the control plots, resulting primarily from increased dominance of C4 plants in the community. Clipping significantly decreased C and N storage in plant and litter pools (all P < 0.05) but did not have interactive effects with warming on either C or N pools over the nine years. Our results suggest that increased ecosystem nitrogen use efficiency via a shift in species composition toward C4 dominance rather than plant N uptake is a key mechanism underlying warming stimulation of plant biomass growth.     

Sustainable wood-based nanotechnologies for photocatalytic degradation of organic contaminants in aquatic environment

•Wood and its reassemblies are ideal substrates to develop novel photocatalysts. •Synthetic methods and mechanisms of wood-derived photocatalysts are summarized. •Advances in wood-derived photocatalysts for organic pollutant removal are summed up. •Metal doping, morphology control and semiconductor coupling methods are highlighted. •Structure-activity relationship and catalytic mechanism of photocatalysts are given. Wood-based nanotechnologies have received much attention in the area of photocatalytic degradation of organic contaminants in aquatic environment in recent years, because of the high abundance and renewability of wood as well as the high reaction activity and unique structural features of these materials. Herein, we present a comprehensive review of the current research activities centering on the development of wood-based nanocatalysts for photodegradation of organic pollutants. This review begins with a brief introduction of the development of photocatalysts and hierarchical structure of wood. The review then focuses on strategies of designing novel photocatalysts based on wood or its recombinants (such as 1D fiber, 2D films and 3D porous gels) using advanced nanotechnology including sol-gel method, hydrothermal method, magnetron sputtering method, dipping method and so on. Next, we highlight typical approaches that improve the photocatalytic property, including metal element doping, morphology control and semiconductor coupling. Also, the structure-activity relationship of photocatalysts is emphasized. Finally, a brief summary and prospect of wood-derived photocatalysts is provided.     

Lagged effect of exports,industrialization and urbanization on carbon footprint in Southeast Asia

The study aims to examine lagged causal effect of economic development policies on the carbon footprint of Southeast Asia. This study employs unit root test, cointegration test and panel data analysis methods to examine endogeneity concerns in observational data. The study applies panel data analysis methods to address unobserved country effect in the model. The balanced panel data includes a total of 240 observations with five cross sections of five nations in Southeast Asia and with 48 time-specific periods of 1970–2017. The results indicate that (1) exports, industrialization, urbanization and economic growth have lagged negative effect on the carbon footprint of the region in the short-run, and (2) there exists a long-run equilibrium relationship among exports, industrialization, urbanization, economic growth and carbon footprint in the region. The findings suggest that the economic growth, exports, industrialization and urbanization of the developing countries in Southeast Asia have been achieved at the cost of increasing the carbon footprint of the region. The findings imply that the environmental policy of the export-led growth countries never have been effective so far since the nations have achieved their economic growth at the high cost of harming the environment of the nations.     

孝感市开放源扬尘重金属污染特征、来源及健康风险评价

为了解开放扬尘源重金属成分谱特征,对孝感市孝南区道路扬尘、土壤扬尘、城市降尘、建筑扬尘和堆场扬尘进行调查取样,利用电感耦合等离子体发射光谱法分析扬尘中重金属的含量,并通过地累积指数法、相关分析、聚类分析和人体健康风险评价法对扬尘重金属污染程度和人体健康风险进行评价.结果 表明,扬尘中Mn、Cr、Zn、Cu、Co和Pb的...     

利用活性污泥制造活性炭的研究

论述了利用在活性污泥法处理废水过程中产生的好氧污泥和厌氧污泥制造活性炭的过程,选择出最佳的制作条件,并进一步测试了产品的性能。实验结果表明,利用剩余活性污泥制造活发现灰这一方法是可行的,并且在最佳条件下制成的活性炭的吸附性能比较令人满意。     

群体感应在Pseudomonas aeruginosa生物强化反硝化中的应用研究

采用模拟废水研究了群体感应对反硝化菌株定植（即生物强化作用）及反硝化作用的影响.反硝化功能基因napA表达结果表明,菌株Pseudomonas aeruginosa能够在反应器中成功定植.通过对不同反应器中信号分子的测定发现,群体感应有利于菌株的定植,硝酸盐的去除效率由55%±3.0%提升至81%±3.8%.在菌株定植成功的反应器中加入群体感应淬灭酶后,信号分子失活,促使反应器中硝酸盐的去除率进一步提升至95%以上.     

于桥水库网箱养鱼对水质影响分析

本文通过采样监测分析了网箱养鱼对水质的影响。分析结果表明,网箱养鱼明显增加了水库水体中藻类密度ＣＯＤ、ＴＰ、ＴＮ的含量,并引起水温上升,溶解氧减少,促进水库富营养化进程,是水质恶化的重要之一。同时,残余饵料和粪便的沉积,增加了底质中的有机质ＴＰ和ＴＮ,造成水库水体的二次污染。     

高Cu、高Zn对白星花金龟幼虫的毒性作用

Cu(铜)和Zn(锌)是环境中最常见的重金属污染元素,为探究其对白星花金龟幼虫的毒性,采用滤纸接触法、人工土壤法和菌渣培养法研究了高Cu、高Zn对白星花金龟幼虫的生长及氧化胁迫效应。结果表明,滤纸接触法和人工土壤法中试验浓度Cu、Zn对白星花金龟幼虫死亡率无明显影响。菌渣培养法中虫体的取食抑制率和体重增长抑制率均与Cu、Zn浓度呈显著性正相关关系;Cu处理诱导了虫体可溶性蛋白含量的增加,抑制了SOD(超氧化物歧化酶)、GST(谷胱甘肽转移酶)的活性和MDA(丙二醛)的产生,对CAT(过氧化物酶)活性没有显著影响;Zn浓度为3 500和5 000 mg·kg-1的处理组可溶性蛋白含量被显著诱导、MDA含量被显著抑制,浓度为2 000和6 500 mg·kg-1处理组的SOD活性被激活(P0.05),Zn胁迫未对CAT、GST活性造成明显影响。表明Cu、Zn污染对白星花金龟幼虫生长具有毒性效应,在评价高浓度的重金属污染对虫体的毒性作用时,不能仅采用SOD、CAT、GST等指标作为标志物,需要综合其他指标进行分析。     

Source diagnostics of polycyclic aromatic hydrocarbons in urban road runoff, dust, rain and canopy throughfall

Diagnostic ratios and multivariate analysis were utilized to apportion polycyclic aromatic hydrocarbon (PAH) sources for road runoff, road dust, rain and canopy throughfall based on samples collected in an urban area of Beijing, China. Three sampling sites representing vehicle lane, bicycle lane and branch road were selected. For road runoff and road dust, vehicular emission and coal combustion were identified as major sources, and the source contributions varied among the sampling sites. For rain, three principal components were apportioned representing coal/oil combustion (54%), vehicular emission (34%) and coking (12%). For canopy throughfall, vehicular emission (56%), coal combustion (30%) and oil combustion (14%) were identified as major sources. Overall, the PAH's source for road runoff mainly reflected that for road dust. Despite site-specific sources, the findings at the study area provided a general picture of PAHs sources for the road runoff system in urban area of Beijing.