Pb-induced changes in roots of two cultivated rice cultivars grown in lead-contaminated soil mediated by smoke

Environmental Science and Pollution Research - Nowadays, public concerns regarding deleterious effect of lead (Pb) is on rise due to its abundance and toxic effect on plants and other living...     

Graphene and its derivatives: synthesis,modifications, and applications in wastewater treatment

Graphene was discovered in 2004 and has attracted intensive interests because of its unique mechanical, electric, thermal, optical, and structural properties, which makes graphene a potential candidate for various applications. Graphene is being used as a composite or filler material with metals, metal oxides, and polymers for potential advanced applications in solar cells, lithium-ion batteries, photocatalysis and sensing. These applications depend upon the distinctive properties of graphene, which in turn depend on the adopted synthetic approach. This article reviews the recent developments in synthesis of graphene and related composite materials. The synthesis of graphene through exfoliation, epitaxial growth and direct growth via carbon source, and modification approaches by covalent and noncovalent methodologies are discussed. Graphene-based metal and metal oxide composites for the purification of wastewater using photolytic process are also presented.     

思林水库荧光溶解性有机质的特征、来源及其转化动力学

利用三维荧光光谱(EEM)结合平行因子分析(PARAFAC),研究了思林水库冬季(1月)、春季(4月)、夏季(6月)和秋季(10月)上游入库水体、库区表层水(0 m)、库区深层水(20 m)、出库水体的荧光溶解性有机质(FDOM)不同组分的特征、来源及其转化动力学.结果表明,思林水库的溶解性有机质由3种荧光组分组成,分别是:陆源类腐殖质(C类,C1)、浮游植物源的微生物类腐殖质(M类,C2)和浮游植物源的类蛋白或类色氨酸或类酪氨酸(C3).其中陆源类腐殖质的荧光强度随着入库水、库区表层水、库区深层水和出库水逐渐减少,这表明由于光化学作用、微生物作用、大坝拦截效应等环境因素的影响,类腐殖质随着水体由入库向出库的流动而逐渐降解.相反,微生物类腐殖质(M类)的荧光强度结果表明,在入库-出库过程中,微生物类腐殖质处于产生及部分或完全降解的波动中,这表明微生物类腐殖质是浮游植物的原生产物,并且对于光化学作用、微生物作用和大坝拦截效应有很强的不稳定性.类蛋白或类色氨酸或类酪氨酸主要新产生于夏季和秋季的表层水体中,在冬季和春季表层和深层水体中也有产生;并在出库过程中逐渐减少.这表明类蛋白或类色氨酸或类酪氨酸是浮游植物的原生产物;并且它们受到光化学作用、微生物作用和大坝拦截效应的共同影响,在表层和深层水中生成和降解.因此,这些结果意味着通过平行因子分析确定的荧光溶解性有机质组分的方法,对于更好地理解溶解性有机质在水库水体的转化动力学机制至关重要.     

Fungicide tolerant Bradyrhizobium japonicum mitigate toxicity and enhance greengram production under hexaconazole stress

Bacterial strain RV9 recovered from greengram nodules tolerated 2400 μg/mL of hexaconazole and was identified by 16 S rDNA sequence analysis as Bradyrhizobium japonicum(KY940048). Strain RV9 produced IAA(61.6 μg/mL), ACC deaminase(51.7 mg/(protein·hr)), solubilized TCP(105 μg/mL), secreted 337.6 μg/mL EPS, and produced SA(52.2 μg/mL) and 2,3-DHBA(28.3 μg/mL). Exopolysaccharides produced by strain RV9 was quantified and characterized by SEM, AFM, EDX and FTIR. Beyond tolerance limit,hexaconazole caused cellular impairment and reduced the viability of strain RV9 revealed by SEM and CLSM. Hexaconazole distorted the root tips and altered nodule structure leading thereby to reduction in the performance of greengram. Also, the level of antioxidant enzymes, proline, TBARS, ROS and cell death was increased in hexaconazole treated plants.CLSM images revealed a concentration dependent increase in the characteristic green and blue fluorescence of hexaconazole treated roots. The application of B. japonicum strain RV9 alleviated the fungicide toxicity and improved the measured plant characteristics. Also,rhizobial cells were localized inside tissues as revealed by CLSM. Colonization of B.japonicum strain RV9 decreased the levels of CAT, POD, APX, GPX and TBARS by 80%, 5%,13%, 13% and 19%, respectively over plants grown at 80 μg/(hexaconazole·kg) soil. The ability to detoxify hexaconazole, colonize plant tissues, secrete PGP bioactive molecules even under fungicide pressure and its unique ability to diminish oxidative stress make B.japonicum an attractive choice for remediation of fungicide polluted soils and to concurrently enhance greengram production under stressed environment.     

Climate change induced eutrophication of cold-water lake in an ecologically fragile nature reserve

Aquatic ecosystem sustainability around the globe is facing crucial challenges because of increasing anthropogenic and natural disturbances. In this study, the Tianchi Lake, a typical cold-water lake and a UNESCO/MAB(Man and Biosphere) nature reserve located in high latitude and elevation with the relatively low intensity of human activity was chosen as a system to examine the linkages between climate change and eutrophication. As a part of the UNESCO Bogda Man and Biosphere Reserve, Tianchi Lake has been well preserved for prevention from human intervention, but why has it been infected with eutrophication recent years? Our results show that climate change played a significant role in the eutrophication in the Tianchi Lake. Increased temperature, changed precipitation pattern and wind-induced hydrodynamic fluctuations in the summer season were suggested to make a major contribution to the accelerated eutrophication. The results also showed that the local temperature and precipitation changes were closely linked to the large-scale atmospheric circulation, which opens the door for the method to be applied in other regions without local climatic information. This study suggests that there is an urgent need to take into consideration of climate change adaptation into the conservation and management of cold-water lakes globally.     

平寨水库荧光溶解性有机质的来源、特征及其动态转化

利用三维激发发射矩阵光谱(3-D EEM)和平行因子分析,研究了三岔河流域平寨水库溶解有机质的来源、组成和转化情况。在平寨水库的入库水、表层水(0～5 m)、深层水(10～60 m)和出库水中,检测到了几种荧光溶解有机质组分,分别为陆源类腐殖质、自源类腐殖质和浮游植物源的类蛋白质(或类色氨酸或类酪氨酸)。陆源类腐殖质的荧光强度在入库水中略高于出库水,表明陆源类腐殖质在水库系统中相对稳定,大坝截流对其影响不大。自源类腐殖质的荧光强度在库区明显高于入库水和出库水,表明自源类腐殖质既由自源有机物分解产生,又在光化学、微生物和大坝物理拦截过程的影响下发生分解;其他荧光组分中也检测到相似的结果。水温、pH、溶解氧和有色溶解有机质表现出相似的季节变化,光化学和微生物以及大坝拦截是引起水库入库水、库区表层水、库区深层水和出库水中荧光溶解有机质时空动态变化的主要原因。     

Classification and ordination of understory vegetation using multivariate techniques in the <Emphasis Type="Italic">Pinus wallichiana</Emphasis> forests of Swat Valley,northern Pakistan

An understory vegetation survey of the Pinus wallichiana-dominated temperate forests of Swat District was carried out to inspect the structure, composition and ecological associations of the forest vegetation. A quadrat method of sampling was used to record the floristic and phytosociological data necessary for the analysis using 300 quadrats of 10 × 10 m each. Some vegetation parameters viz. frequency and density for trees (overstory vegetation) as well as for the understory vegetation were recorded. The results revealed that in total, 92 species belonging to 77 different genera and 45 families existed in the area. The largest families were Asteraceae, Rosaceae and Lamiaceae with 12, ten and nine species, respectively. Ward’s agglomerative cluster analysis for tree species resulted in three floristically and ecologically distinct community types along different topographic and soil variables. Importance value indices (IVI) were also calculated for understory vegetation and were subjected to ordination techniques, i.e. canonical correspondence analysis (CCA) and detrended correspondence analysis (DCA). DCA bi-plots for stands show that most of the stands were scattered around the centre of the DCA bi-plot, identified by two slightly scattered clusters. DCA for species bi-plot clearly identified three clusters of species revealing three types of understory communities in the study area. Results of the CCA were somewhat different from the DCA showing the impact of environmental variables on the understory species. CCA results reveal that three environmental variables, i.e. altitude, slope and P (mg/kg), have a strong influence on distribution of stands and species. Impact of tree species on the understory vegetation was also tested by CCA which showed that four tree species, i.e. P. wallichiana A.B. Jackson, Juglans regia Linn., Quercus dilatata Lindl. ex Royle and Cedrus deodara (Roxb. ex Lamb.) G. Don, have strong influences on associated understory vegetation. It is therefore concluded that Swat District has various microclimatic zones with suitable environmental variables to support distinct flora.     

Effect of acetate on lead toxicity to microbial biomass in a red soil

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