Changes in the grassland-forest boundary at Ta-Ta-Chia long term ecological research (LTER) site detected by stable isotope ratios of soil organic matter

The carbon isotope analysis [delta13C values] of organic samples can be a useful research in ecological studies because delta13C values are indicative of the plant source. This study investigated the changes in plant communities along the grassland-forest boundary in the alpine forest at Ta-Ta-Chia long term ecological research (LTER) site in central Taiwan using carbon isotope data. The aim of this study was focused on the forest fire affected the change of vegetation community. Four pedons from grassland dominated by Miscanthus transmorrisonensis (pedons 1 and 2), transition zone by Tsuga and Yushania nittakeyamensis (pedon 3), and forest zone by Tsuga and nittakeyamensis (pedon 4) were examined. Soil organic matter (SOM) delta13C values in the upper soil horizon were similar to delta13C values of the overlaying vegetation types. This indicates that the boundary between these plant communities remained the same in the past decades. The delta13C values of the grassland SOM ranged from -19.4 per thousand to -24.1 per thousand, showing decrease with soil depth. This suggests that C4 plants (transmorrisonensis) have replaced C3 plants of Tsuga and nittakeyamensis. The delta13C values of the Tsuga forest area (pedon 4) range from -27.0 per thousand to -23.5 per thousand and showed only slight change with soil depth, implying that C3 plants have remained the major species in the forest.     

环境激素污染研究进展及污染防治

环境激素具有类雌激素活性 ,能对生物和人体的内分泌机能造成影响 ;环境激素污染可导致各种生物的生殖功能下降和生殖器免疫力降低 ,并引起各种生理异常。本文对国内外环境重金属激素和有机激素的研究进行了综述 ,并总结了防治环境激素污染的主要技术手段 ;指出环境激素致毒生物化学机理研究、环境激素在环境介质中的迁移 转化 积累的行为研究、环境激素容量分析以及环境激素物质的进一步筛选是国际环境科学领域的重要研究方向和前沿领域。     

Sensitivity analyses of woody species exposed to air pollution based on ecophysiological measurements

GOAL, SCOPE AND BACKGROUND: Air pollution has been of a major problem in the Pearl River Delta of south China, particularly during the last two decades. Emissions of air pollutants from industries have already led to damages in natural communities and environments in a wide range of the Delta area. Leaf parameters such as chlorophyll fluorescence, leaf area (LA), dry weight (DW) and leaf mass per area (LMA) had once been used as specific indexes of environmental stress. This study aims to determine in situ if the daily variation of chlorophyll fluorescence and other ecophysiological parameters in five seedlings of three woody species, Ilex rotunda, Ficus microcarpa and Machilus chinensis, could be used alone or in combination with other measurements for sensitivity indexes to make diagnoses under air pollution stress and, hence, to choose the correct tree species for urban afforestation in the Delta area. METHODS: Five seedlings of each species were transplanted in pot containers after their acclimation under shadowing conditions. Chlorophyll fluorescence measurements were made in situ by a portable fluorometer (OS-30, Opti-sciences, U.S.A). Ten random samples of leaves were picked from each species for LA measurements by area-meter (CI-203, CID, Inc., U.S.A). DW was determined after the leaf samples were dried to a constant weight at 65 degrees C. LMA was calculated as the ratio of DW/LA. Leaf N content was analyzed according to the Kjeldhal method, and the extraction of pigments was carried out according Lin et al. RESULTS AND DISCUSSION: The daily mean Fv/Fm (Fv is the variable fluorescence and Fm is the maximum fluorescence) analysis showed that Ilex rotunda and Ficus microcarpa were more highly resistant to pollution stress, followed by Machilus chinensis, implying that the efficiency of photosystem II in I. rotunda was less affected by air pollutants than the other two species. Little difference in daily change of Fv/Fm in I. rotunda between the polluted and the clean site was also observed. However, a relatively large variation of Fv/Fm appeared in the other two species, particularly in M. chinensis, suggesting that they were more sensitive to air pollutants than I. rotunda. The mean LA was reduced for all species growing at the polluted site. The mean LMA for all species exceeded the sclerophylly threshold given by Cowling and Campbell and increased for those under pollution stress, which could be explained as one of the acclimation strategies for plants to air pollution stress. Little difference in leaf chlorophyll content was observed in F. microcarpa and M. chinensis, while remarkable differences were found in I. rotunda growing at the polluted and the clean site. Content of leaf carotenoids was largely reduced in I. rotunda growing at the polluted site, but increased in F. microcarpa and M. chinensis, compared with plants growing at the clean site. Plants growing at the clean site had a lower leaf N content than those growing at the polluted site. In addition, species with a higher resistance to pollution stress showed less difference in leaf N content than those sensitive species. CONCLUSION: Based on Fv/Fm measurements of the three woody species, I. rotunda showed the highest resistance to air pollutants from ceramic industries, followed by F. microcarpa. M. chinensis was the most sensitive species to air pollution, had lowest capacities to cope with the air pollution stress, which was consistent with visual injury symptoms observed in the crown profiles of plants at the polluted site. Fv/Fm, LAM, LA, leaf pigments and N content could be used alone or in combination to diagnose the extent of the physiological injury. The ratio of Fv/Fm, however, was the best and most effective parameter. RECOMMENDATION AND OUTLOOK: Tree species which have higher air-pollutant resistance, as diagnosed by such ecophysiological parameters, should be considered first and planted widely for urban afforestation or forest regeneration in areas where the forest was seriously degraded or forest health was markedly effected by the same kind of air pollutants.     

榉树扦插育苗初探

榉树是一个珍稀名贵的树种,同时,又是一个濒危树种,本文叙述了榉树的生物学特性、繁殖方式,介绍了榉树扦插育苗的方法。     

高等水生植物中镉的富集分配规律及危害

本文报道了四种水生植物——狐尾藻、水葫芦、紫背萍、荇菜对水体镉污染的反应和它们的净化作用。其结果是:植物的不同种类、不同器官、不同生态习性的不同镉富集量;水体镉浓度与植物的富集量之间有显著相关;富集系数因植物种和器官不同而异;随镉浓度的上升,叶细胞膜受损,叶绿素含量和叶绿素a/b比率下降;植物内部的破坏先于外部;植物的抗性顺序为水葫芦>狐尾藻>荇菜>紫背萍。作者认为水葫芦对水体镉污染具有较理想的净化作用,紫背萍则是较好的监测植物。     

汽车排气净化催化剂三效性能的研究

本文对Ky系列催化剂处理汽车排气中CO,HC和NO_x的三效性能进行了研究,用CVS法测定排放污染物的重量和转化效率;通过行车60 000km,证明高温老化引起催化剂表面结构的改变,是导致催化剂活性下降的主要原因,新改进的催化剂有较好的热稳定性和三效性能。     

直流电场强化活性污泥法处理木质素废水的效能、污泥特性及群落结构研究

以溶解态木质素模拟废水为研究对象,考察了不同直流电场条件下活性污泥反应器(R1,无电流,悬浮污泥)、电极生物膜反应器(R2,电流I=10~60 mA,无悬浮污泥)与电极生物膜-活性污泥反应器(R3,I=10~60 mA,悬浮污泥)中木质素废水的处理效能、污泥生理特性(活菌比、木质素过氧化物酶(LiP)、三磷酸腺苷(ATP)等)、细胞膜磷脂脂肪酸组成及微生物群落结构的差异.结果表明:相同的外加电流下,R3的木质素去除率均高于R2(p0.05),其中,30 mA时达到最大值30.19%±0.47%,分别为R1、R2木质素去除率的2.01倍和1.46倍.反应器R2在20~40 mA时的总氮去除效果最好,达到71.96%±5.79%.分析R1、R3悬浮污泥发现,外加电流升高不改变悬浮污泥的活菌比(p0.05),木质素去除率受LiP酶活影响不大;与低电流(10~30 mA)相比,高电流(40~60 mA)下悬浮污泥中C15∶0 ANTEISO的含量降低,长链磷脂脂肪酸(C19、C20)的相对含量增加;R3悬浮污泥中Flavobacterium、Pseudomonas和Janthinobacterium等可降解木质素的菌属在10 mA外加电流的刺激下相对丰度均最高.在电极微生物方面,与R3相比,R2阴极微生物中具有反硝化能力的Methyloversatilis成为优势菌属,阳极微生物中存在更多具有电子传递能力的菌属(Pseudomonas、Ralstonia).冗余分析(RDA)表明,悬浮污泥中Mycobacterium(降解木质素的好氧细菌)丰度与电流(I)显著正相关(p0.05),与不饱和脂肪酸(UFA)显著负相关(p0.05).     

Large variability in ambient ozone sensitivity across 19 ethylenediurea-treated Chinese cultivars of soybean is driven by total ascorbate

The sensitivity of Chinese soybean cultivars to ambient ozone(O3) in the field is unknown,although soybean is a major staple food in China. Using ethylenediurea(EDU) as an O3 protectant, we tested the gas exchange, pigments, antioxidants and biomass of 19 cultivars exposed to 28 ppm·hr AOT40(accumulated O3 over an hourly concentration threshold of40 ppb) over the growing season at a field site in China. By comparing the average biomass with and without EDU, we estimated the cultivar-specific sensitivity to O3 and ranked the cultivars from very tolerant( 10% change) to highly sensitive( 45% change), which helps in choosing the best-suited cultivars for local cultivation. Higher lipid peroxidation and activity of the ascorbate peroxidase enzyme were major responses to O3 damage, which eventually translated into lower biomass production. The constitutional level of total ascorbate in the leaves was the most important parameter explaining O3 sensitivity among these cultivars. Surprisingly, the role of stomatal conductance was insignificant. These results will guide future breeding efforts towards more O3-tolerant cultivars in China, while strategies for implementing control measures of regional O3 pollution are being implemented. Overall, these results suggest that present ambient O3 pollution is a serious concern for soybean in China, which highlights the urgent need for policy-making actions to protect this critical staple food.     

生物炭输入土壤对其石油烃微生物降解力的影响

以木屑和麦秆为原料,在300℃和500℃下热解制备生物炭,分析了生物炭输入对大港油田污染土壤中总石油烃及其组分(正链烷烃n C8~C40和16种PAHs)微生物降解效果的影响.结果表明,生物炭输入强化了土壤中总石油烃及其组分的生物降解.生物炭原料的选取对烷烃降解影响显著,对PAHs影响较小;高温制备生物炭对污染物降解的强化效果较好,这归因于生物炭表面性质和降解微生物种类的不同.土壤中加入生物炭后,低环PAHs的降解效率显著高于高环PAHs.添加典型的土壤易分解有机质(葡萄糖)产生正激发作用,导致生物炭矿化,促进了烷烃降解,抑制了PAHs的去除.可见,生物炭输入可有效促进石油烃的微生物降解,对修复石油污染土壤起正效应.