三江平原春小麦农田生态系统氧化亚氮通量特征

利用静态暗箱-气相色谱法对三江平原春小麦农田生态系统N2O排放通量进行连续2.5年的田间原位观测.结果表明:三江平原春小麦农田生态系统N2O排放通量具有较明显的季节变化和年际变化,并主要与年际间降水及田间水分管理差异有关;春小麦农田生态系统N2O排放日变化与气温及地下5 cm温度变化有关.生长期N2O的排放较强,休耕期N2O排放量显著下降,冰冻期N2O的排放较微弱,融冻时N2O排放缓慢增强.生长期N2O平均排放通量为0.190 mg.m-2.h-1,收割后到冰冻期间为0.077 mg.m-2.h-1,冻融期间为0.017 mg.m-2.h-1.     

赤潮水体中胶体物质对赤潮异弯藻(Heterosigma akashiwo)和中肋骨条藻(Skeletonema costatum)生长的影响

2004年2月9～10日在胶州湾发生的柔弱几内亚藻(Guinardia delicatula)赤潮期间分别在3个典型赤潮站位采集表层水样,利用过滤(0.7μm)和切向超滤(1000 Daltons)分离赤潮暴发水体中的胶体物质,分析了不同滤液及截留液的有机碳含量,并将赤潮异弯藻 (Heterosigma akashiwo)和中肋骨条藻(Skeletonema costatum)在<1000 Daltons的超滤液及具有不同含量胶体物质(1000 Daltons～0.7μm)的截留液中进行培养.结果发现在发生柔弱几内亚藻赤潮期间水体中的溶解有机碳浓度会增加,特别是胶体有机碳浓度会成倍增长;在不同胶体含量海水中培养的赤潮异弯藻的最大生长率μmax和最大生物量Bf与对照组相比会随着胶体含量的增加而显著增大,而中肋骨条藻的最大生长率μmax和最大生物量Bf与对照组相比会随着胶体含量增加而显著降低,表明柔弱几内亚藻赤潮水体中的胶体物质对赤潮异弯藻的生长起促进作用,而对中肋骨条藻的生长起抑制作用.这说明柔弱几内亚藻在增殖过程中所产生的胶体物质具有他感作用,会影响其它微藻的生长,从而可能对柔弱几内亚藻赤潮的形成起重要作用.     

硅对机体内铝的影响

硅对机体内铝的影响黎玉（江西医学院化学教研室,南昌３３０００６）关键词硅硅酸铝硅是生命必需的元素之一。近年来,对硅的研究有了很大的进展,除了证实它是骨组织、软骨组织和结缔组织正常生长所必需的元素外,还有研究发现硅能抑制铝在体内的吸收、促进铝的排泄、减...     

铝对荞麦根系的影响

以荞麦为试材,用五种剂量的铝进行土培,发现低浓度(0.435+0.6gAl3+/kg土)的铝能增加荞麦的总根长、根尖数和根系活力,减小根平均直径,降低根质膜透性,对荞麦生长有一定的促进作用;高浓度的铝(0.435+1.2gAl3+/kg土)会使荞麦的根变短、变粗、侧根减少,根系活力下降,根质膜透性升高,明显不利于荞麦的生长发育。     

铝对豌豆生长的影响

研究酸性条件下不同浓度Al^3 对豌豆根芽生长的影响。结果表明,Al对豌豆根芽的生长有显著的抑制作用,对豌豆根尖细胞分裂产生危害的初始浓度为1mg.L^-1,Al诱导豌豆根尖染色体发生多种类型畸变,初始浓度为0．5mg.L^-1,低浓度下Al对豌豆根芽生长的抑制与植物对Ca、Mg的吸收没有明显的相关性。     

大米草对赤潮藻的抑制作用及其抑藻物质的分离鉴定

以赤潮异弯藻和海洋原甲藻为研究对象,研究了海洋滩涂植物大米草对两种赤潮微藻的抑制作用及抑藻物质.结果表明：大米草对赤潮异弯藻的影响表现为高浓度抑制生长,低浓度则有一定的促进作用,大米草新鲜组织、干粉末和提取物浓度分别为4.8、0.8和0.5 mg·ml^-1以上时对赤潮异弯藻有致死作用;大米草对海洋原甲藻则表现出明显的抑制作用,且大米草新鲜组织、干粉末和提取物浓度分别为9.6、1.6和1.25 mg·ml^-1以上时对海洋原甲藻有致死作用.对大米草提取物进行抑藻活性物质的分离纯化,从中分离鉴定了2个具有抑藻活性的黄酮糖苷类化合物：异鼠李素-3-O-槐二糖-7-O-鼠李糖苷和丁香亭-3-O-半乳糖苷.     

铝对玉米生长和硝酸还原酶活性的影响

测定了生长在Ａｌ２（ＳＯ４）３１００μｍｏｌ／Ｌ氮素营养液中的两个玉米品种（ＳＣ７０４和ＶＡ３５的根系和叶片）的ＮＡＤＨ－硝酸还原酶（ＥＣ１．６．６．１）和ＮＡＤ（Ｐ）Ｈ－硝酸还原酶（ＥＣ１．６．６．２）活性。     

铝对秋茄幼苗生理特性的影响

为探讨铝对秋茄幼苗生理特性的影响,实验研究了不同浓度铝盐(0-100 mmol/L AlCl3)处理后秋茄的各种生理反应,对幼苗的生长、净光合效率、膜脂过氧化作用、游离脯氨酸含量等生理指标与胁迫程度及时间的关系作了对比研究,特别分析了高浓度(25-100 mmol/L Al3+)胁迫下,秋茄叶片和根部活性氧清除系统保护酶活性的变化趋势。研究发现,在10 mmol/L浓度以下,秋茄在生理特性上表现出对铝胁迫的最大适应性,能维持正常生命生长过程。当浓度增加至25-100 mmol/L,秋茄的生理反应较为敏感,膜脂过氧化加重,MDA含量及保护酶活性随铝浓度增加的变化趋势与其在海莲中的表现基本相似。高浓度铝胁迫的极端环境使植物体内产生过量的活性氧自由基,诱导了细胞膜系统的氧化损伤,最终导致秋茄植株衰老甚至死亡。抗氧化保护酶系统SOD、CAT、POD的协同作用,在一定时间内可以维持细胞内活性氧代谢平衡;特别是POD被激活的程度最大,且持续时间最长,可以考虑作为秋茄幼苗抗铝胁迫的生理标志。秋茄叶片和根部的游离脯氨酸含量在25和100 mmol/L Al3+胁迫下均显著增加。       

酸度和铝对马尾松生长的影响

用溶液培养法研究了铝对马尾松 ( Pinus massoniana)幼苗生长的影响。马尾松耐酸性较强 ,在 p H为 3.5— 5 .5范围内均能正常生长。马尾松对铝中度敏感 ,在 p H4 .0条件下 ,铝毒害的阈值浓度为 4 .0 ppm。铝在溶液中存在的状态依 p H值而变化 ,不同形态的铝离子对马尾松的毒性不同 :Al3 的毒性大于 Al( OH) 2 和 Al( OH) 2 。极低浓度 ( <0 .1 5 mmol/L)的 Al3 对马尾松生长有刺激作用。 Ca2 对 Al3 的毒性有拮抗作用 ,对马尾松产生抑制作用的 Al/Ca摩尔比小于 1     

Reflections on the ballast water dispersal—harmful algal bloom paradigm

The ballast water dispersal—HAB paradigm, increasingly invoked circumstantially to explain puzzling and unaccountable HAB species outbreaks when lacking the multiple tests of confirmation recommended by Bolch and de Salas (2007), is evaluated. The types and examples of natural dispersions and taxon cycles are compared to exotic species bloom behavior linked to ballast water vectoring. The regional spreading, bloom behavior and disjunct distributions of the brown tide pelagophyte Aureococcus anophagefferens and the toxic dinoflagellate Gymnodinium catenatum, attributed to ballast water vectoring, are used as representative examples to evaluate the general application of the ballast water—HAB paradigm and associated interpretative problems. Human-aided emigration has a seeding and colonization ecology that differs from bloom ecology. For self-sustaining blooms to occur, these two ecologies must be accommodated by habitat growth conditions. The three stages that a non-native species must pass through (pioneering, persistence, community entry) to achieve colonization, community maintenance, and to bloom, and the niche-related factors and role of habitat disturbance are discussed. The relevance of cryptic occurrences, cyst deposits, dormancy periods and bloom rhythms of HAB species to their blooms attributed to ballast water-assisted introductions is also sketched. The different forms of HAB species rarity, their impact on the ballast water dispersal—HAB paradigm, and the dispersion and blooms of specialist and generalist HAB species are discussed. The remarkable novel and, often, monospecific blooms of dinoflagellate HAB species are being paralleled by similar eruptive bloom behavior cutting across phylogenetic lines, and being found also in raphidophytes, haptophytes, diatoms, silicoflagellates, etc. These blooms cannot be explained only as seeding events. An ecological release of ‘old barriers’ appears to be occurring generally at coastal bloom sites, i.e. something significant is happening ecologically and embedded within the ballast water—HAB paradigm. There may be a relationship between Life Form type [Smayda, T.J., Reynolds, C.S., 2001. Community assembly in marine phytoplankton: application of recent models to harmful dinoflagellate blooms. J. Plankton Res. 23, 447–461] and mode of expatriation; HAB dinoflagellate species commonly reported to produce ballast water-assisted toxic blooms invariably are members of cyst-producing Life Forms IV, V, VI. Ballast water vectoring of Life Forms I, II, III is rarely reported, even though many produce cysts, and where their novel introductions do occur they are more likely to be ichthyotoxic and vectored in shellfish stock consignments. The relevance of, and need to distinguish between morphospecies and their geographic/ribotype clades are discussed based on the Alexandrium tamarense/catenella/fundyense complex. Morphospecies-level ballast water dispersions are probably minor compared to the dispersal of the different ribotypes (toxic/non-toxic clades) making up HAB morphospecies; the redistribution and admixture of genotypes should be the focus. Ballast water-assisted expatriations impact the global occurrence of HABs through the direct transfer of previously absent species or introduction of genetic strains from the donor habitat that are ecologically favored over resident strains. The hybridization of species may be of potentially greater impact, resulting from the (1) mating of individuals from the donor and recipient habitats, or (2) through the interbreeding of strains introduced from two different donor sites into the recipient site, and whose progeny have greater ecological fitness than indigenous strains. Exceptional ecological changes of some sort appear to be occurring globally which, in combination with the genetically altered ecophysiological behavior of HAB species linked to ballast water dispersion and admixture, underpins the global HAB phenomenon. The impact of ballast water and shellfish transplantation on HABs and phytoplankton community ecology, generally, is considerably greater than the current focus on HAB species distributions, vectoring, and blooms. The methodological, investigative and conceptual potential of the ballast water—HAB paradigm should be exploited by developing a GEOHAB type intiative to advance quantification of global HAB ecology.     

A fluorometric method for the discrimination of harmful algal bloom species developed by wavelet analysis

An in vivo 3D fluorescence discrimination technique for ten harmful algal bloom (HAB) species that belong to eight genera of four divisions was developed by wavelet analysis. Daubechies-7 (db7) was employed as the mother wavelet. The fifth scale domains were selected as the discriminant characteristic spectra (DCS). Based on the DCS, The phytoplankton species at different growth stages were classified correctly at both the division and the genus level by Bayesian discriminant analysis (BDA). Based on the reference spectra of the DCS, the discrimination method of the phytoplankton species was established by the nonnegative least squares (NNLS) method. The correct discrimination ratios (CDRs) for samples of the single species were 96.1% with 0% blank noise and 93.3% with 10% noise at the genus level, while the CDRs were both 100% with 0% or 10% blank noise at the division level. When blank noise was up to 20%, the CDRs were down to 85.2% at the genus level and 98.0% at the division level. For the mixture samples, the CDRs of the dominant species were 98.3% and 96.3%, respectively, at the division level and at the genus level. As dominant species, Prorocentrum minimum (Pm), Gymnodinium simplex (Gs), Scrippsiella trochoidea (Sc), Skeletonema costatuma (Sk), Chaetoceros (Cu and De), Phaeocystis globosa (Cg) and Chlorella pynnoidosa (Ch) can be correctly discriminated at both the division level and the genus level.     

The value of harmful algal bloom predictions to the nearshore commercial shellfish fishery in the Gulf of Maine

In this study, we develop a framework for measuring the value of harmful algal bloom (HAB) predictions. The framework captures the effects of both private and public responses to HABs. Using data from the New England nearshore commercial shellfish fishery and impact estimates for a large-scale HAB event in 2005, we illustrate how the potential value of HAB forecasts may be estimated. The results of our study suggest that the long-term value of a HAB prediction and tracking system for the Gulf of Maine is sensitive to the frequency of HAB events, the accuracy of predictions, the choice of HAB impact measures, and the effectiveness of public and private responses.     

Dinoflagellate cysts from surface sediments of Saldanha Bay, South Africa: an indication of the potential risk of harmful algal blooms

The distribution and abundance of dinoflagellate cysts from recent coastal sediments in Saldanha Bay, was investigated, and compared to the cyst assemblages of the adjacent coastal upwelling system as reflected in the sediments off Lambert's Bay on the southern Namaqua shelf. Twenty-two cyst types were identified from three sample sites off Lambert's Bay with recorded abundances between 1726 and 1863 cysts ml⁻¹ wet sediment. At least 21 distinctive cyst types were identified from 32 sample sites within Saldanha Bay. Cyst abundance in Saldanha Bay was relatively low, averaging 116 cysts ml⁻¹ wet sediment. The region off Lambert's Bay is especially susceptible to the formation of harmful algal blooms attributed to high biomass dinoflagellate blooms. Owing to these blooms and the retentive circulation characteristics of this area, cyst formation and deposition is high. Blooms can be advected into Saldanha Bay, but their development and duration in the Bay is restricted by the system of exchange that operates between the Bay and the coastal upwelling system, in that there is a net export of surface waters from the Bay. Consequently, fewer cysts are formed and deposited within the Bay thereby reducing the likelihood of in situ bloom development initiated from the excystment of cysts.     

具齿原甲藻的生态特征及赤潮成因浅析

在东海的长江口和舟山海域,2000-2002年连续3年的5月发生罕见的大规模赤潮,赤潮生物为具齿原甲藻,为了解该种的生态特征及赤潮频发原因,本文分析近赤潮应急监测资料及野外生态调查资料,结果表明,该种适温,适盐范围分别为15-25℃和14-32,最适温度,盐度分别为18-22℃和22-31,该种运动能力较强,在海流交汇的紊乱水体中具有强适应能力,具有昼夜垂直移动特性,水温,硝酸盐含量,海流及上升流,磷限制环境下的种间竞争优势对诱发和维持赤潮具有重要作用.     

舟山海域春季浮游植物生物量及东海原甲藻赤潮频发机制初探

通过2002和2003年春季2个航次对东海舟山群岛及其邻域大面站的浮游植物及期间爆发的大规模东海原甲藻(Prorocentrum donghaiense)赤潮的综合调查,研究了调查海区浮游植物叶绿素a和营养盐的分布特性,分析了赤潮高发区域的生态环境特征,探讨了诱发和控制海域赤潮发生的环境因子.结果表明,2002和2003年春季大面站表层平均叶绿素a浓度分别为1.09±1.63和4.21±5.33 mg·m^-3,调查海区平均为0.70±0.48和2.60±2.99 mg·m^-3,叶绿素a浓度的高值区基本上位于122.5°～123°E间冲淡水形成的锋面区域,此区域营养盐可以得到充分补充,光照条件适宜,也是浮游植物生产力的高值带.2002和2003年东海原甲藻赤潮跟踪期间,表层平均叶绿素a浓度分别高达18.45±11.04和12.47±8.15 mg·m^-3.赤潮发生海域盐度在26～30,赤潮藻生长易受磷的限制.光照条件适宜、营养盐(特别是磷酸盐)能得到较快的补充及锋面辐聚带的形成是赤潮形成的重要条件.     

Use of two-dimensional gel electrophoresis proteome reference maps of dinoflagellates for species recognition of causative agents of harmful algal blooms

The sample preparation procedures established for Prorocentrum triestinum were adapted to cover both thecate and athecate dinoflagellates. Further, whether trichloroacetic acid (TCA) precipitation can be used to fix and preserve the harmful or nuisance species from local waters that they infest was tested. Optimized technical procedures developed were used to generate proteome reference maps for eight other local causative species of harmful algal blooms (HABs): Prorocentrum micans, Prorocentrum minimum, Prorocentrum sigmoides, Prorocentrum dentatum, Scrippsiella trochoidea, Karenia longicanalis, Karenia digitata and Karenia mikimotoi; together with one American species Karenia brevis (Florida, USA). These proteome maps were used to test their ability for species recognition in a mixed culture of dinoflagellates and whether such investigations will provide a comparative view at a global level. Comparisons of proteome profiles were made (i). between closely related species within the same family; (ii). between distantly related species belonging to different types, i.e., gymnodinioids, prorocentroids or peridinioids, or (iii). between different groups, i.e., thecate (armored) dinoflagellate cells against athecate (naked or unarmored) dinoflagellate cells. Species-specific two-dimensional electrophoresis (2-DE) protein profiles were observed in all ten species and it was possible to distinguish between even closely related species within the same family. To demonstrate the extent of reproducibility and usefulness of these 2-DE reference maps, 2-DE has been used to analyze three geographically distinct isolates of Prorocentrum dentatum, and to distinguish species composition in a mixed culture. Application of 2-D PAGE analysis to differentiate between taxonomically confused strains of a single species could be a powerful taxonomic tool.     

Novel algicidal evidence of a bacterium Bacillus sp. LP-10 killing Phaeocystis globosa,a harmful algal bloom causing species

While searching for effective bio-agents to control harmful algal blooms (HABs), the bacterial strain LP-10, which has strong algicidal activity against Phaeocystis globosa (Prymnesiophyceae), was isolated from surface seawater samples taken from the East China Sea. 16S rDNA sequence analysis and morphological characteristics revealed the strain LP-10 belonged to the genus Bacillus. The lytic effect of Bacillus sp. LP-10 against P. globosa was both concentration- and time-dependent. Algicidal activities of different growth stages of the bacterial culture varied significantly. The lytic effect of different parts of the bacterial cultures indicated that the algal cells were lysed by algicidal active compounds in the cell-free filtrate. Analysis of the properties of the active compounds showed that they had a molecular weight of less than 1000 Da and that the active compounds were stable between −80 and 121 °C. The algicidal range assay indicated that five other algal species were also suppressed by strain LP-10, including: Alexandrium catenella, A. tamarense, A. minutum, Prorocentrum micans and Asterionella japonica. Our results suggested that the algicidal bacterium Bacillus sp. LP-10 could be a potential bio-agent to control the blooms of harmful algal species.     

A retrospective appraisal of the importance of high-resolution sampling for harmful algal blooms: Lessons from long-term phytoplankton monitoring at Sherkin Island,S.W. Ireland

The ongoing Sherkin Island Marine Station phytoplankton monitoring programme began in 1978. The present stations were established in 1980. Surveying has been carried out continuously since then, employing a more comprehensive sampling strategy than the few other published long-term records. Examples are presented here of cell concentrations for several HAB species and other bloom species from the Sherkin Island record. These show far more short-term and long-term natural variation in time and space than might be expected from the other records in the literature used to investigate HAB, suggesting that ecological complexity may be critically misrepresented in such investigations. This has serious implications for scientists evaluating reports of past HAB (what cell densities were responsible?) and predicting future HAB. Evidence presented here also suggests limitations that should be recognized in using cell concentrations from plankton in models for predictions of HAB.