南沙群岛邻近海区春夏季浮游植物多样性研究

1999年春季和夏季对南沙海区网采浮游植物分布与多样性进行了调查。 1999年春季渚碧礁湖观测站及春、夏季大面站的浮游植物细胞数量平均值分别为 2 .4 9× 10 4cells/m3 、0 .73× 10 4cells/m3 和 1.0 3× 10 4cells/m3 。1999年春季在渚碧礁湖共采到浮游植物 2 6属 5 1种 ,大面站 31属 10 9种 ;夏季大面站共检出 38属 172种。海区大面站春季、夏季浮游植物Shannon Wiener多样性指数平均值分别为 4 .35和 4 .0 1;春季渚碧礁浮游植物多样性指数为 2 .92 ,低于外部开阔海域。南沙海区浮游植物的分布与水文、营养盐、浮游动物的摄食等均有一定的关系     

初秋南沙群岛海域网采浮游植物群落特征及其与环境因子的关系

根据2011年8-9月南沙群岛海域的生物和环境调查资料,对网采浮游植物的群落特征及其与环境因子的关系进行分析.结果表明: 在鉴定的3门34属113种网采浮游植物中,甲藻门和硅藻门种类各占57.5%和40.7%,其中硅藻门的角藻属种类最多,占30.1%.网采浮游植物平均丰度为2.12×10⁴ cell·m^-3,丰度高值区出现在北部礼乐滩多涡区域和南部万安气旋涡附近海域.蓝藻门束毛藻属是网采浮游植物的主要功能群,占海域平均丰度的77.0%.主要优势种为铁氏束毛藻、红海束毛藻和夜光梨甲藻.优势种(类)存在较明显的空间差异,蓝藻门在S₃、S₅、S₆和S₁₀~S₁₄站占优势;甲藻门在中部S₄、S₇~S₉站占优势,硅藻门在南部S₁和S₂站占优势.网采浮游植物多样性和均匀度指数分别为3.10和0.62.影响浮游植物群落特征的重要环境因子有盐度、水温、铵氮、亚硝酸盐、磷酸盐和硅酸盐,以及南沙中尺度气旋涡和南沙西部沿岸流.典范对应分析排序图较好地显示了浮游植物和环境因子之间的关系.     

重金属镉对水稻根毛细胞钾离子吸收过程的影响

重金属镉进入植物体后会引起一系列的毒害反应,然而迄今为止有关镉毒害的机制并不明了。本研究综合使用了膜电势测定、非损伤微测和膜片钳等电生理学实验技术,检测了镉对水稻根毛细胞钾离子吸收过程的影响。研究结果显示,外源施用50μmol·L-1 CdCl2能明显造成水稻根毛细胞膜的去极化,抑制根毛细胞质膜内向K＋通道活性,同时诱导外向K＋通道开放,导致根系内K＋外渗,进而降低了水稻根部K＋含量。通过上述影响,镉扰乱了水稻根系对钾离子的吸收过程,造成钾元素缺失,成为植物体镉毒害作用的机理之一。     

Unimodal size scaling of phytoplankton growth and the size dependence of nutrient uptake and use

Phytoplankton size structure is key for the ecology and biogeochemistry of pelagic ecosystems, but the relationship between cell size and maximum growth rate (μ_max) is not yet well understood. We used cultures of 22 species of marine phytoplankton from five phyla, ranging from 0.1 to 10⁶ μm³ in cell volume (V_cell), to determine experimentally the size dependence of growth, metabolic rate, elemental stoichiometry and nutrient uptake. We show that both μ_max and carbon‐specific photosynthesis peak at intermediate cell sizes. Maximum nitrogen uptake rate (V_maxN) scales isometrically with V_cell, whereas nitrogen minimum quota scales as V_cell^0.84. Large cells thus possess high ability to take up nitrogen, relative to their requirements, and large storage capacity, but their growth is limited by the conversion of nutrients into biomass. Small species show similar volume‐specific V_maxN compared to their larger counterparts, but have higher nitrogen requirements. We suggest that the unimodal size scaling of phytoplankton growth arises from taxon‐independent, size‐related constraints in nutrient uptake, requirement and assimilation.     

Light and nutrient availability affect the size-scaling of growth in phytoplankton

Communities of marine phytoplankton consist of cells of many different sizes. The size-structure of these communities often varies predictably with environmental conditions in aquatic systems. It has been hypothesized that physiological differences in nutrient and light requirements and acquisition efficiencies contribute to commonly observed correlations between phytoplankton community size structure and resource availability. Using physiological models we assess how light and nutrient availability can alter the relative growth rates of phytoplankton species of different cell sizes. Our models predict a change in the size dependence of growth rate depending on the severity of limitation by light and nutrient availability. Under conditions of growth-saturated resource supply, phytoplankton growth rate (mol C ) scales with cell volume with a size-scaling exponent of ; light limitation reduces the size-scaling exponent to approximately , and nutrient limitation decreases the exponent to as a consequence of the size-scaling of resource acquisition. Exponents intermediate between and occur under intermediate availability of light and nutrients and depend on the size-scaling of pigment photoacclimation and the size range examined.     

Influences of rice straw biochar and organic manure on forage soybean nutrient and Cd uptake

Abstract

This pot experiment aimed to investigate the influence of rice straw biochar (BC 0, 1, and 3%, w/w) and organic manure (OM 0, 1, and 2%, w/w) addition on the growth, nutrient and cadmium (Cd) uptake of forage soybean in 10 mg Cd kg^?1 contaminated soils. Compared with non-biochar treatments, biochar decreased shoot biomass, height and nitrogen (N) contents. Organic manure markedly increased the shoot biomass, shoot phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg) concentration, and root N, P, Ca contents without biochar addition treatments, while in the case of 3% biochar, there were no significant effects on N, K, Ca, and Mg contents of shoot and root among organic manure treatments. In comparison with other treatments, the minimum Cd content of shoots and roots both occurred in the treatment of BC3%+OM2%, while shoot Cd content reached the maximum value in OM2% treatment. Thus, these results suggested that organic manure addition can elevate forage soybean yield and nutrient content, while biochar had no positive effects. High biochar (3%) addition in combination with highest dose of organic manure (2%) can decline the Cd content of soybean and contribute to the agricultural product safety.     

Effects of nutrient enrichment on the growth rates and community structure of summer phytoplankton from the Gulf of Riga, Baltic Sea

Sea water collected in mid-July was spiked with different combinationsof nutrients. Dissolved inorganic nitrogen (DIN) became exhausted,while significant amounts of P-PO₄ and Si-SiO₃ remained available.NH₄ was taken up before NO₃, but, in some cultures, NO₃ uptakeappears to have started in the presence of     

Genetic diversity of small eukaryotes from the coastal waters of Nansha Islands in China

Population structures and genetic diversity of the small eukaryotic plankton from the coastal waters of the Nansha Islands in China were investigated. Two genes libraries using 18S rDNA of the marine small eukaryotes were constituted, and 323 clones were identified within alveolates (more than 43%), acanthareas, viridiplantaes, and stramenopiles. Many novel clones were detected in the two libraries, including two groups of alveolates and two clades related to both acanthareas and polycystineas. Several sequences unrelated to any other known eukaryotes may represent early branches in the phylogenetic tree. Our results reveal that there is a high diversity and abundance of small eukaryotes in the marine regions of China.     

缓/控释肥料对辣椒生长及养分利用率的影响

采用盆栽试验方法,连续3年研究了不同缓/控释肥料在辣椒上的施用效果.结果表明：与常规分次施肥处理（T¹）相比,一次性施用聚合物包膜控释肥处理（T²）提高了辣椒的单果质量和维生素C含量,改善了根系活力,产量平均提高8.4％,但可溶性糖含量没有明显变化;施用磷酸铵镁包膜控释肥处理（T₃）的单果质量和维生素C含量与T₁无显著差异,但可溶性糖含量提高了5.67%,根系活力在生育前期旺盛,后期较弱,平均产量略有降低;而3种缓释肥处理则提高了果实的可溶性糖含量,显著改善了根系活力,但平均产量与T₁无显著差异.在养分利用方面,除T₂处理氮钾利用率提高、磷素利用率降低外,其他缓/控释肥料处理的氮、磷、钾利用率均明显提高.表明合理施用缓/控释肥料能改善辣椒的根系活力,提高养分利用率.     

Effects of aluminium on growth and nutrient uptake of small Picea abies and Pinus sylvestris plants

Summary The effects of aluminium concentrations between 0.2 and 30 mM at pH 3.8 ±0.2 on small plants of Norway spruce [(Picea abies (L.) Karst], Scots pine (Pinus sylvestris L.), and Scots pine infected with the ectomycorrhizal fungus Suillus bovinus (L. ex Fr.) O. Kuntze were investigated. The plants were grown at maximum relative growth rate (R_G % day^–1) with free access but very low external concentrations of nutrients. Steady-state conditions with respect to relative growth rate (R_G) and internal nutrient concentrations were achieved before addition of aluminium, which was added as AlCl₃ and/or Al(NO₃)₃. There were reductions in rg at aluminium concentrations of 0.3 mM in spruce, 6 mM in pine and 10 mM in ectomycorrhizal pine, i. e. at aluminium concentrations considerably higher than those normally occurring in the top layer of the mineral soil where most fine roots are found. Nutrient uptake rate per unit root growth rate was calculated for different nutrient elements. The uptake rate of calcium and magnesium was reduced at aluminium concentrations of 0.2 mM (spruce), 1 mM (pine) and 3 mM (ectomycorrhizal pine), without influencing R_g. The results question the validity of the hypothesis of aluminium toxicity to forest tree species at low external concentrations.     

Metal uptake by different species of phytoplankton in culture

Cadmium and copper uptake by cultures of Prasinocladus marinus, Amphidinium carterae, Chaetoceros curvisetum and Chaetoceros protuberans was considered as a function of exposure time (from 0.5 to 72 h) and of metal concentrations added to the culture medium (from 5 to 20 µg l^–1). For cadmium uptake, A. carterae exhibited a particular behaviour: the accumulation was not dependent on exposure time or on metal concentration. An adsorption process appeared to govern both Cadmium uptake by phytoplankton species (except A. carterae) and that of copper. In addition to adsorption, another active process might be involved in the Cadmium uptake of P. marinus, C. curvisetum and C. protuberans.     

硒对镉胁迫下水稻幼苗生长及生理特性的影响

采用溶液培养 ,研究不同浓度的硒和镉处理对稻苗的株高、叶片干重、叶绿素、还原糖、叶片丙二醛含量以及保护酶 SOD、POD、CAT活性的影响。结果表明 ,镉胁迫下稻苗矮化 ,镉毒害使叶片失绿 ,干重降低 ,还原糖含量下降 ,叶片 MDA含量增加 ,POD活性增强 ,而 SOD、CAT活性降低 ;硒可减轻镉对水稻的毒害 ,表现为 :减轻镉胁迫对株高增加的抑制 ,提高叶绿素含量 ,增加叶片干物质积累 ,提高叶片还原糖含量 (Cd0 .5 mg/ L加 Se 0 .1 0～ 0 .5 0 mg/ L例外 ) ,降低 MDA含量与 POD活性 ,提高 SOD、CAT活性     

Potential phytoplankton indicator species for monitoring Baltic coastal waters in the summer period

There are very few time series documenting clear trends of change in the biomass of total phytoplankton or single taxa that coincide with trends of increasing nutrient concentrations. Weekly or biweekly monitoring since 1997 on a cross section of the central Gulf of Finland (NE Baltic Sea) with similar climatic and hydrographic conditions, but different nutrient levels, provided a uniform dataset. In order to evaluate seasonal (June–September) patterns of phytoplankton succession, more than 1,200 samples were statistically analyzed by selecting 12 dominant taxa using wet weight biomass values. In addition, the continuously measured hydrographic parameters on board the ships of opportunity, and simultaneous nutrient analyses gave high frequency information on the water masses. The objective of this study was to identify the taxa that may prove indicative in the assessment of eutrophication in the appropriate monitoring time periods. None of the most common bloom-forming species (Aphanizomenon sp., Nodularia spumigena, and Heterocapsa triquetra) showed reliable correlations with enhanced nutrient concentrations. The species we suggest as reliable eutrophication indicators—oscillatorialean cyanobacteria and the diatoms Cyclotella choctawhatcheeana and Cylindrotheca closterium—showed the best relationships with total phosphorus concentrations. Their maxima appear toward the end of July or in August–September when phytoplankton community structure is more stable, and less frequent observations may give adequate results. Another diatom, Skeletonema costatum, exhibited stronger correlations with dissolved inorganic and total nitrogen in June, during the period of the summer phytoplankton minimum. Guest editors: J. H. Andersen & D. J. Conley Eutrophication in Coastal Ecosystems: Selected papers from the Second International Symposium on Research and Management of Eutrophication in Coastal Ecosystems, 20–23 June 2006, Nyborg, Denmark     

Size-fractionated productivity and nutrient dynamics of phytoplankton in subtropical coastal environments

It is now well established that the size distribution of phytoplankton plays an important role in primary production processes and nutrient dynamics of coastal environment. In situ observations showed that nanophytoplankton (3–20 μm) contributed 72.08% and58.18% of phytoplankton biomass and 58.32% and 41.14% of primary productivity to Xiamen Western Waters and the northern Taiwan Strait, respectively; picophytoplankton (0.2–3 μm) dominated the biomass (64.70%) and productivity (66.09%) in the southern Taiwan Strait. Furthermore, nanophytoplankton accounted for 75% of phosphate uptake with the highest rate constant (8.3×10^-5 s^-1) and uptake rate in unit water volume (5.4×10^-5 mmol dm^-3s^-1); picophytoplankton had the highest uptake rate in unit biomass (5.4×10^-5 mmol mg^-1s^-1) and photosynthetic index (3.8 mgC mgChl a^-1h^-1). All the results highlighted the remarkable characteristics of small size ranged (0.2–20 μm) phytoplankton in subtropical coastal environments: main contributor to phytoplankton biomass and production, high efficiency on organic carbon production and nutrient recycling. The far reaching environmental and ecological implications were discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

耕作播种方式对稻茬小麦生长和养分吸收利用的影响

2016—2018年,在四川省广汉市分析了深旋耕播种(DRT)、浅旋耕播种(SRT)和免耕带旋播种(NT)3种耕播方式对稻茬小麦生长和养分吸收利用的影响。结果表明:与DRT相比,SRT和NT处理提高了小麦分蘖、成穗能力。2016—2017年,处理间产量无显著差异;2017—2018年,NT处理产量显著高于DRT,增幅10.9%。处理间干物质积累的差异主要在苗期。NT处理下植株对氮的吸收量高于DRT,平均增幅9.9%,而氮收获指数DRT高于NT;各处理植株磷吸收量差异不显著;NT处理对钾的吸收量显著高于DRT。与传统的深旋耕播种方式相比,免耕带旋播种技术是提高稻茬小麦产量和养分吸收的有效途径。     

有机物料对污染土壤上水稻生长和重金属吸收的影响

采用盆栽试验,研究了施用有机碳源、菜籽饼和猪粪对污染土壤上水稻生长和重金属吸收特性的影响.结果表明： 施用菜籽饼和猪粪均能缓解重金属对水稻的毒害作用,促进水稻生长,显著增加地上部生物量和籽粒产量,降低糙米中重金属浓度;而有机碳源抑制水稻生长.与施用化肥相比,施用菜籽饼和猪粪处理的水稻籽粒产量分别增加128.3%和67.9%;施用菜籽饼处理的糙米Cd、Cu和Zn浓度分别降低47.6%、35.2%和21.5%,施用猪粪处理分别降低9.5%、21.2%和9.3%.土壤中DTPA提取态重金属浓度与水稻地上部生物量和重金属积累总量呈显著负相关.     

夏季胶州湾微型浮游动物摄食初步研究

2002年6月至7月间对胶州湾内、外和港口3个典型站位进行了微型浮游动物对浮游植物的摄食研究．按陆基半现场方式进行了4次稀释法实验,对湾外相同的站位进行了两次实验,对湾内和港口各进行了一次实验,获取了研究站位浮游植物和微型浮游动物种类、丰度、体积转换浮游植物碳含量、碳／叶绿素比率、浮游植物净生长率、微型浮游动物摄食率、对潜在初级生产力的摄食压力、对浮游植物现存量的摄食压力以及碳摄食通量等参数．湾外和湾内站位的浮游植物组成相似,优势种为新月柱鞘藻(Cylindrotheca closterium)和中肋骨条藻(Skeletonema costatum),港口浮游植物优势种类为中肋骨条藻、浮动湾角藻(Eucampia zodiacus)和旋链角毛藻(Chaetoceros curvisetus)．湾外微型浮游动物的优势种为百乐拟铃虫(Tintinnopsis beroidea),而在湾内为百乐拟铃虫和急游虫(Strombidium sp．),港口主要为急游虫,也有少数的百乐拟铃虫．微型浮游动物对浮游植物的摄食率和对潜在初级生产力的摄食压力,在湾内最高,其次在湾外,港口最低．微型浮游动物对浮游植物的摄食率,在湾外,分别为0．96和1．20d^-1,在湾内为1．33d^-1,在港口为0．36d^-1．微型浮游动物对潜在初级生产力的摄食压力,在湾外,分别为74％和84％,在湾内为93％,在港口为53％．微型浮游动物的碳摄食通量在港口最高达到281mgC·m^-3·d^-1,在湾内为102mgC·m^-3·d^-1,在湾外最低范围在31～49mgC·m^-3·d^-1．浮游植物的细胞大小和两种微型浮游动物的摄食习性的不同是造成研究站位微型浮游动物摄食率和摄食压力不同的主要原因．同世界其它内湾相比,胶州湾微型浮游动物的摄食压力处于中等水平。