Distribution and vertical migration of polycyclic aromatic hydrocarbons in forest soil pits of southeastern Tibet

PAHs could be transported to Tibetan Plateau in accompany with atmospheric circulation. The forest regions were found be an important sink for PAHs, while their distributions and migrations in forest are still uncertain. In this study, soil profile samples were collected in southeastern Tibet and the concentrations, distributions, and migration of PAHs in forest region were investigated. The PAHs levels in the forest soils were at the low end of remote sites, ranged from 27.4 to 120.3 ng g^?1 on a dry weight based. Due to low ambient temperature and high organic carbon content, enrichment of PAHs was found in higher altitude on north side. According to the soil profiles, the vertical distributions of PAHs in organic layers were mainly influenced by pedogenesis, while the vertical distributions in mineral layers were dominated by downward leaching effect. Enrich factor (EF) of PAHs was estimated, and the values in organic layers were positively correlated with the octanol–air partition coefficients (K _OA), but EFs in mineral layers decreased with the K _OA values. PAHs in the surface soils on the north side of forest were relatively stable, while the migration of PAHs on the south sides and other clearing sites was more active. The leaching rates of PAHs in clearing site ranged between 1.42 and 29.3%. The results from this study are valuable on the characterization of PAHs in Tibetan Plateau.     

Catalytic reduction for water treatment

Treating water contaminants via heterogeneously catalyzed reduction reaction is a subject of growing interest due to its good activity and superior selectivity compared to conventional technology, yielding products that are non-toxic or substantially less toxic. This article reviews the application of catalytic reduction as a progressive approach to treat different types of contaminants in water, which covers hydrodehalogenation for wastewater treatment and hydrogenation of nitrate/nitrite for groundwater remediation. For hydrodehalogenation, an overview of the existing treatment technologies is provided with an assessment of the advantages of catalytic reduction over the conventional methodologies. Catalyst design for feasible catalytic reactions is considered with a critical analysis of the pertinent literature. For hydrogenation, hydrogenation of nitrate/nitrite contaminants in water is mainly focused. Several important nitrate reduction catalysts are discussed relating to their preparation method and catalytic performance. In addition, novel approach of catalytic reduction using in situ synthesized H₂ evolved from water splitting reaction is illustrated. Finally, the challenges and perspective for the extensive application of catalytic reduction technology in water treatment are discussed. This review provides key information to our community to apply catalytic reduction approach for water treatment.

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滨海滩涂不同围垦年代垦区农作物重金属累积特征及其与氮、磷的关系

为探明滨海滩涂围垦区农作物重金属累积特征及其与围垦年代、作物氮磷含量及化学计量比的关系,采集盐城地区不同围垦年代(围垦20、30、40、60年)农田4种主要作物(大麦、小麦、油菜、蚕豆)样品63个,测定了其根、茎叶和籽粒中Cd、Cu、Zn、Pb、Hg、As及全氮(N)、全磷(P)和粗蛋白(CP)含量,分析了重金属累积特征及与围垦年代、N、P、CP及N/P比的关系,并采用单因子污染指数法和内梅罗综合污染指数法对重金属污染程度和安全水平进行了评价。结果表明,1)围垦农田作物整株各指标含量分别为Cd (0.52±0.94)、Cu (12.98±16.00)、Zn (34.93±27.91)、Pb (3.50±5.88)、Hg (0.0063±0.0063)、As (1.94±3.72) mg·kg~(-1)及N(13.69±8.27)、P (5.98±2.24)、CP (79.55±49.54) g·kg~(-1);籽粒中则分别为(0.0059±0.020)、(1.83±1.48)、(11.13±4.45)、(0.09±0.30)、(0.0023±0.0036)、(0.0021±0.0048) mg·kg~(-1)及(19.21±7.68)、(6.04±1.64)、(111.78±47.81) g·kg~(-1); 2)作物重金属均表现为根茎叶籽粒,N和CP与之相反,表现为根茎叶籽粒,而P则表现为根籽粒茎叶; 3)不同围垦年代之间作物重金属、N、P、CP含量、N/P比及综合污染指数(Pz)均没有显著差异(P0.05); 4)各作物籽粒6种重金属单因子污染指数均值均小于1,除个别样品Pb超标(超标率11%)外,其他重金属均未超标; 5)作物籽粒重金属Pz均值为0.38,表明该地区作物重金属总体处于安全级,但大麦、小麦、油菜籽粒均有样品Pb含量超过警戒线,个别样品甚至达到重度污染水平; 6)作物整株各重金属之间、重金属与P之间均存在显著正相关(P0.01),而重金属与N、CP、N/P存在显著负相关(P0.01),在籽粒中则相关性均不显著(P0.05)。以上结果显示,盐城滨海滩涂围垦区作物重金属累积与围垦时间关系不大,其含量目前尚处于可接受范围内,但Pb污染值得关注,作物重金属与P之间存在一定的相互促进作用,而与N存在一定的拮抗作用,高氮低磷的机体养分状况有助于降低重金属含量。     

Heterologous overexpression of Populus euphratica BAK1;1 gene enhanced resistance to Pst DC3000 in tobacco北大核心CSCD

BRI1-ASSOCIATED RECEPTORKINASE1(BAK1), a leucine-rich repeat (LRR) receptor protein kinase, plays a significant role in brassinosteroid (BR) signaling. Furthermore, it combines with other LRR-RLKs protein to initiate immune response in plants. The objective of this study was to (1) investigate the function of the Populus euphratica BAK1;1 gene in the resistance of transgenic tobacco to Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) and (2) discuss the regulation pathway of PeBAK1;1 involved in the resistance to plant pathogen. We cloned the cDNA sequence of the P. euphratica PeBAK1;1 gene, constructed the pBI121-35S::PeBAK1;1 over-expression vector, and then transformed it into wild-type tobacco by Agrobacterium-mediated transformation to obtain PeBA K 1;1-overexpressing transgenic tobacco plants. The bioinformatic analysis showed that the PeBAK1;1 protein contained all the structural features of the plant SERK family. The phylogenetic tree showed that PeBAK1;1 has the highest sequence homology with PtBAK1. The gene expression profile results indicated that the expression of PeBAK1;1 in the root was higher than that in the leaf and stem. The wild-type tobacco plants showed an obvious susceptibility to Pst DC3000, whereas the transgenic plants exhibited enhanced resistance to Pst DC3000. Compared with that of the wild-type (WT), the real-time PCR and quantitative real-time PCR analysis revealed that the expression of pathogenesis-related genes (including PR1, PR3, PR4, and PR5), BAK1-interacting receptor kinase 1 gene, and BONZAI1 gene was upregulated in 35S::PeBAK1;1 transgenic tobacco plants. In conclusion, the PeBAK1;1 gene plays a positive regulatory role in 35S::PeBAK1;1 transgenic tobacco against Pst DC3000, which can enhance the resistance of plants to pathogen. © 2018 Science Press. All rights reserved.     

High CO<Subscript>2</Subscript> adsorption by amino-modified bio-spherical cellulose nanofibres aerogels

Climate change has become increasingly serious due to the greenhouse effect. It is therefore necessary to control the content of greenhouse gases such as carbon dioxide in the atmosphere, using, for instance, CO₂-adsorbing materials. Here, we synthesized ultra-lightweight and spherical cellulose nanofibres aerogels by a suspension titration method using an efficient amination process. These functional materials with high porosity, higher than 96.54%, and three-dimensional network structure, were prepared by freeze-drying spherical cellulose nanofibres hydrogel. Their maximum CO₂ adsorption capacity reaches 1.78 mmol/g, and they show excellent regeneration, of more than 10 cycles. This synthesis of bioaerogels represents a new method for the preparation of bio-CO₂ adsorbents.     

漂浮负载型光催化剂制备及降解草甘膦研究

以漂珠(FP)为载体,采用溶胶-凝胶-浸渍法制备了漂浮负载型CdS/TiO2/FP复合膜光催化剂,通过SEM、XRD对其结构进行了表征.以甘草膦农药的光催化降解为模型反应,使用不同光源研究了CdS/TiO2/FP的光催化性能,探讨了影响催化剂活性的因素及采用太阳光做光源处理草甘膦的可行性.结果表明,经4层镀膜500℃热处理的20%(w/w)CdS/TiO2/FP光催化剂具有良好的光催化性能,最佳降解条件为:催化剂加入量3 g/L,初始pH 7～9,Fe2 浓度为2.0×10-3 mol/L.通气量200 mL/min.在最佳条件下,对135 mg/L草甘膦溶液降解率可以分别达到96.3%(125 W高压汞灯,60 min)和82.4%(太阳光,180 min).     

Enhancement of heavy metal accumulation by tissue specific co-expression of iaaM and ACC deaminase genes in plants

The aerobic riboflavin (Rf)-sensitized photodegradation of the endocrine disruptor 4,4'-isopropylidenebisphenol (bisphenol A, BPA), and of the related compounds 4,4'-isopropylidenebis(2,6-dibromophenol) and 4,4'-isopropylidenebis(2,6-dimethylphenol) has been studied in water and water-methanol mixtures through visible-light continuous photolysis, polarographic detection of oxygen uptake, stationary and time-resolved fluorescence spectroscopy, time-resolved near-IR phosphorescence detection and laser flash photolysis techniques. Bisphenols (BPs) quench excited singlet and triplet states of Rf, with rate constants close to the diffusion limit. BPs and dissolved molecular oxygen, employed in similar concentrations, competitively quench triplet excited Rf. As a consequence, superoxide radical anion and singlet molecular oxygen (O(2)((1)Delta(g))) are produced by electron- and energy-transfer processes, respectively, as demonstrated by auxiliary experiments employing selective quenchers of both oxidative species and the exclusive O(2)((1)Delta(g)) generator Rose Bengal. As a global result, the photodegradation of Rf is retarded, whereas BPs are degraded, mainly by an O(2)((1)Delta(g))-mediated mechanism, which constitutes a relatively efficient process in the case of BPA. Oxidation, dimerization and fragmentation products have been identified in the photooxidation of BPA. Results indicate that BPs in natural waters can undergo spontaneous photodegradation under environmental conditions in the presence of adequate photosensitizers.     

AB工艺污水厂冬季运行效果分析

对乌鲁木齐市某AB工艺污水厂冬季实际运行效果进行监测分析。结果表明：冬季水温降低不影响AB工艺对BOD₅的去除效果,BOD5的去除率平均达到88.8%,但COD和SS的去除效果下降;在A段氨氮去除率为35%,经过B段后,氨氮含量反又上升,去除率下降为7.8%左右;降低了A段除磷效果,去除率仅29%,B段则表现出稳定的除磷效果,出水总磷稳定在1.0 mg/L以下,AB工艺总磷去除率达到80%。     

Aging activity of DDE in dissimilar rice soils in a greenhouse experiment

A green-house study was conducted in late 2005 to investigate the aging behavior of p,p'-DDE in two types of soil, Hydragric Anthrosols (An) and Hydragric Acrisols (Ac), according to the World Reference Base (WRB) [FAO/ISRIC/ISSS. 1998. World reference base for soil resources. World soil resources reports, Rome. p. 87]. Paddy rice and dry rice were grown in submerged paddy soils and non-submerged upland soils, respectively. The concentration of extractable p,p'-DDE in fresh DDE-spiked soils was 746.2ngg(-1). During the first few weeks of the experiment, the extractability of p,p'-DDE became increasingly low as the aging period prolonged. However, certain amount of p,p'-DDE that had been captured by soil minerals and organic matter (OM) could be released and became extractable in the later period. The extractability of p,p'-DDE in submerged soils was significantly lower than that in non-submerged soil, because flooding could increase the binding of pollutants to soil particles. The plantation of both dry rice and paddy rice slowed down the aging process of p,p'-DDE. After one month's growth of rice, p,p'-DDE bound to soil particles was released and became extractable. The OM and silt content of An are higher than that of Ac, resulting in more bound residues and relative lower extractability of p,p'-DDE in An. In addition, the extractability of p,p'-DDE could be reduced by the addition of rice straw to soils.     

Non-microcystin producing Microcystis wesenbergii (Komárek) Komárek (Cyanobacteria) representing a main waterbloom-forming species in Chinese waters

It is well known that several morphospecies of Microcystis, such as Microcystis aeruginosa (Kützing) Lemmermann and Microcystis viridis (A. Brown) Lemmermann can produce hepatotoxic microcystins. However, previous studies gave contradictory conclusions about microcystin production of Microcystis wesenbergii (Komárek) Komárek. In the present study, ten Microcystis morphospecies were identified in waterblooms of seven Chinese waterbodies, and Microcystis wesenbergii was shown as the dominant species in these waters. More than 250 single colonies of M. wesenbergii were chosen, under morphological identification, to examine whether M. wesenbergii produce hepatotoxic microcystin by using multiplex PCR for molecular detection of a region (mcyA) of microcystin synthesis genes, and chemical analyses of microcystin content by ELISA and HPLC for 21 isolated strains of M. wesenbergii from these waters were also performed. Both molecular and chemical methods demonstrated that M. wesenbergii from Chinese waters did not produce microcystin.