The Southern Ocean biological response to aeolian iron deposition

Biogeochemical rate processes in the Southern Ocean have an important impact on the global environment. Here, we summarize an extensive set of published and new data that establishes the pattern of gross primary production and net community production over large areas of the Southern Ocean. We compare these rates with model estimates of dissolved iron that is added to surface waters by aerosols. This comparison shows that net community production, which is comparable to export production, is proportional to modeled input of soluble iron in aerosols. Our results strengthen the evidence that the addition of aerosol iron fertilizes export production in the Southern Ocean. The data also show that aerosol iron input particularly enhances gross primary production over the large area of the Southern Ocean downwind of dry continental areas.     

Novel Role for Phycoerythrin in a Marine Cyanobacterium, Synechococcus Strain DC2

Cyanobacterial picoplankton contribute substantially to oceanic primary productivity. The colored protein phycoerythrin is the major component of their light-harvesting apparatus. It was found that in Synechococcus strain DC2 a variable proportion of the light energy absorbed by phycoerythrin is lost as autofluorescence and therefore is not passed to a photoreaction center. Phycoerythrin may serve two functionally distinct roles in this organism: as a nitrogen reserve and as a collector of quanta for photosynthesis.     

Phosphorus in cold-water corals as a proxy for seawater nutrient chemistry

Phosphorus is a key macronutrient being strongly enriched in the deep ocean as a result of continuous export and remineralization of biomass from primary production. We show that phosphorus incorporated within the skeletons of the cosmopolitan cold-water coral Desmophyllum dianthus is directly proportional to the ambient seawater phosphorus concentration and thus may serve as a paleo-oceanographic proxy for variations in ocean productivity as well as changes in the residence times and sources of deep-water masses. The application of this tool to fossil specimens from the Mediterranean reveals phosphorus-enriched bottom waters at the end of the Younger Dryas period.     

Mesoscale eddies drive increased silica export in the subtropical Pacific Ocean

Mesoscale eddies may play a critical role in ocean biogeochemistry by increasing nutrient supply, primary production, and efficiency of the biological pump, that is, the ratio of carbon export to primary production in otherwise nutrient-deficient waters. We examined a diatom bloom within a cold-core cyclonic eddy off Hawaii. Eddy primary production, community biomass, and size composition were markedly enhanced but had little effect on the carbon export ratio. Instead, the system functioned as a selective silica pump. Strong trophic coupling and inefficient organic export may be general characteristics of community perturbation responses in the warm waters of the Pacific Ocean.     

Comment on "The Southern Ocean biological response to aeolian iron deposition"

Cassar et al. (Reports, 24 August 2007, p. 1067) proposed that aerosol-iron input enhances Southern Ocean export production. Their conclusion critically depends upon aerosol-iron modeling simulations not validated with iron-deposition data and dust dissolution rates based on Northern Hemisphere atmospheric chemical conditions (low pH). This diminishes the relevance of their findings and demonstrates that applying such models to this region is premature.     

Biogeochemical Controls and Feedbacks on Ocean Primary Production

Changes in oceanic primary production, linked to changes in the network of global biogeochemical cycles, have profoundly influenced the geochemistry of Earth for over 3 billion years. In the contemporary ocean, photosynthetic carbon fixation by marine phytoplankton leads to formation of approximately 45 gigatons of organic carbon per annum, of which 16 gigatons are exported to the ocean interior. Changes in the magnitude of total and export production can strongly influence atmospheric CO2 levels (and hence climate) on geological time scales, as well as set upper bounds for sustainable fisheries harvest. The two fluxes are critically dependent on geophysical processes that determine mixed-layer depth, nutrient fluxes to and within the ocean, and food-web structure. Because the average turnover time of phytoplankton carbon in the ocean is on the order of a week or less, total and export production are extremely sensitive to external forcing and consequently are seldom in steady state. Elucidating the biogeochemical controls and feedbacks on primary production is essential to understanding how oceanic biota responded to and affected natural climatic variability in the geological past, and will respond to anthropogenically influenced changes in coming decades. One of the most crucial feedbacks results from changes in radiative forcing on the hydrological cycle, which influences the aeolian iron flux and, in turn, affects nitrogen fixation and primary production in the oceans.     

泰国榴莲出口潜力研究

水果是泰国重要的农产品经济结构系统的支柱产业,其中榴莲是泰国第二大出口水果。目前在泰国的几乎所有地区都有扩大生产和增加种植面积的发展趋势。虽然榴莲的出口率有所上升,但还没有满足生产市场的需求,特别是在旱季中期的榴莲集中上市季节,通常会发生由于产量过多造成滞销或使榴莲市场价格持续下降的问题。因此,本研究通过采用SWOT分析法,对目前泰国榴莲出口进行研究分析,希望有助于提高泰国榴莲的出口潜力。研究发现,泰国榴莲出口的特色或优势在于:拥有适合的土壤和适宜的气候条件进行榴莲种植,并且有足够的面积扩大榴莲种植,榴莲的单位面积产量高等等;而劣势在于:受到技术知识不足的限制,种植过程中经常受到植物病虫害的影响,并且农民通常使用传统农作方式,生产效率较低等等。     

Compact plant type rice has higher lodging and N resistance under machine transplanting

To identify the major factors that contribute to the difference in lodging among different rice varieties under machine transplanting and their responses to nitrogen(N), field experiments were conducted at Danyang County(a representative eco-site of the Lower Yangtze River) in Jiangsu Province, China in 2017 and 2018, 22 hybrid indica varieties(HIs), 22 inbred japonica varieties(IJs) and two indica japonica hybrid varieties(IJHs) were transplanted by machine with three N rates(N0, N150 and N300, 0, 150 and 300 kg ha–1, respectively). Lodging-related physical parameters, morphological characteristics and apparent transport rates of dry matter were examined. Significant difference in yield was observed among different types of rice, and followed by IJsHIsIJHs. The average lodging index(LI) of hybrid varieties(HIs and IJHs) was higher than that of the inbred varieties(IJs) with higher plant height; moreover, lower apparent export rate of dry matter resulted lower LI in IJHs than in HIs. The HIs had a large difference in the LI, which came from the difference in bending stress(BS) induced by the difference in the apparent export rate of dry matter, varieties with lower leaf angle of upper three leaves possess strong lodging resistance capacity; however, the gap among the IJs was due to the difference in the cross section modulus(Z). The LI in the IJs or IJHs increased slightly with the increased N application, and there was no lodging incidence under the high N level, which was due to the low leaf angle and barely changed under high N; there was a significant interaction between varieties(HIs) and N rates in lodging rate and LI, varieties with lower leaf angle of upper three leaves were resistant to high N. These results suggest that compact plant type rice has higher lodging and N resistance at machine-transplanting method.     

技术性贸易壁垒对茶叶出口影响的实证分析——以福建省为例

福建省是我国茶叶生产和出口大省,茶叶产业是福建省农业主导产业之一。分析了福建省茶叶出口现状,应用贸易引力模型来实证分析国外技术性贸易壁垒对该省茶叶出口的影响。最后提出福建省茶叶出口应对国外技术性贸易壁垒的政策建议     

Eddy/wind interactions stimulate extraordinary mid-ocean plankton blooms

Episodic eddy-driven upwelling may supply a significant fraction of the nutrients required to sustain primary productivity of the subtropical ocean. New observations in the northwest Atlantic reveal that, although plankton blooms occur in both cyclones and mode-water eddies, the biological responses differ. Mode-water eddies can generate extraordinary diatom biomass and primary production at depth, relative to the time series near Bermuda. These blooms are sustained by eddy/wind interactions, which amplify the eddy-induced upwelling. In contrast, eddy/wind interactions dampen eddy-induced upwelling in cyclones. Carbon export inferred from oxygen anomalies in eddy cores is one to three times as much as annual new production for the region.     

应对国际新标准，发展福建乌龙茶出口

目前日本“肯定列表制度”和欧盟茶叶新标准等新标准的提出,阻碍了福建乌龙茶的出口贸易。本文从当前乌龙茶的生产情况和国际新标准的要求、特征出发,试图提出了相应的建议措施,即采用适当的农药、呼吁国际市场统一茶叶标准及推动乌龙茶生产加工的规模化、集约化来推动福建乌龙茶的出口贸易。     

Physical and biological controls on carbon cycling in the equatorial pacific

The equatorial Pacific is the largest oceanic source of carbon dioxide to the atmosphere and has been proposed to be a major site of organic carbon export to the deep sea. Study of the chemistry and biology of this area from 170 degrees to 95 degrees W suggests that variability of remote winds in the western Pacific and tropical instability waves are the major factors controlling chemical and biological variability. The reason is that most of the biological production is based on recycled nutrients; only a few of the nutrients transported to the surface by upwelling are taken up by photosynthesis. Biological cycling within the euphotic zone is efficient, and the export of carbon fixed by photosynthesis is small. The fluxes of carbon dioxide to the atmosphere and particulate organic carbon to the deep sea were about 0.3 gigatons per year, and the production of dissolved organic carbon was about three times as large. The data establish El Ni?o events as the main source of interannual variability.     

出口香葱标准化周年生产技术的研究

为满足真空冷冻干燥食品生产流水线的需要,生产出符合出口要求的优质小香葱产品,对国内外部分小香葱材料进行品比试验,筛选出德国小香葱为主推品种;并制定了《出口香葱标准化生产技术规程》,结果表明,按规程种植香葱增产率达21%,采收期可延长3个月。     

广东省出口商品结构分析

从出口商品结构的角度,对广东省1987—2007年的的初级产品出口、工业制成品出口和GDP的统计数据,运用协整等方法分析了其出口商品结构同经济增长的关系,得出结论:短期内,初级产品出口促进经济增长,工业制成品出口抑制经济增长;长期内,出口商品结构的优化则对经济增长有稳定的促进作用。     

Vertical nitrate fluxes in the oligotrophic ocean

The vertical flux of nitrate across the thermocline in the upper ocean imposes a rigorous constraint on the rate of export of organic carbon from the surface layer of the sea. This export is the primary means by which the oceans can serve as a sink for atmospheric carbon dioxide. For the oligotrophic open ocean regions, which make up more than 75% of the world's ocean, the rate of export is currently uncertain by an order of magnitude. For most of the year, the vertical flux of nitrate is that due to vertical turbulent transport of deep water rich in nitrate into the relatively impoverished surface layer. Direct measurements of rates of turbulent kinetic energy dissipation, coupled with highly resolved vertical profiles of nitrate and density in the oligotrophic eastern Atlantic showed that the rate of transport, averaged over 2 weeks, was 0.14 (0.002 to 0.89, 95% confidence interval) millimole of nitrate per square meter per day and was statistically no different from the integrated rate of nitrate uptake as measured by incorporation of (15)N-labeled nitrate. The stoichiometrically equivalent loss of carbon from the upper ocean, which is the relevant quantity for the carbon dioxide and climate question, is then fixed at 0.90 (0.01 to 5.70) millimole of carbon per square meter per day. These rates are much lower than recent estimates based on in situ changes in oxygen over annual scales; they are consistent with a biologically unproductive oligotrophic ocean.     

世界荔枝生产贸易格局与竞争力分析

基于世界荔枝生产、贸易格局及其变化特征,测算了世界荔枝生产与贸易大国的出口竞争力状况,结果表明,我国荔枝出口总体上具有国际竞争力,但和其他荔枝主要出口国相比,差距还较大,并据此提出相关的对策建议.     

不同熟期甘蓝制种组合的播种期试验

不同熟期甘蓝制种组合的播种期试验结果表明：早、中、晚熟甘蓝品种的抽薹率均与低温来临时植株的营养体大小呈正比关系,营养体越犬抽薹率越高;其中早熟甘蓝对茎粗及叶片数量要求最低,中熟甘蓝次之;晚熟甘蓝对植株营养体大小要求最高,各个熟期甘蓝的开花期和播种期基本呈正比关系,即播种期越早,开花期也会随之提早;早熟甘蓝品种制种在江苏句容的适宜播种期为9月5日左右;中熟甘蓝品种制种的适宜播种期为8月25日左右;晚熟甘蓝品种的适宜播种期为8月15～25日。     

我国蔬菜出口的影响因素分析——基于面板数据的引力模型

【目的】分析我国蔬菜出口的主要影响因素,为制定我国蔬菜出口战略提供理论依据。【方法】对我国蔬菜近年来出口贸易的现状和特点进行分析,并采用2003~2013年的面板数据构建贸易引力模型,研究我国和出口目的地的国内生产总值(GDP)、地理距离、我国和出口目的地蔬菜产量及APEC成员身份等因素对我国蔬菜出口的影响。【结果】我国蔬菜产量、出口目的地的APEC成员身份、我国和出口目的地的GDP等4个因素与我国蔬菜的出口额呈正相关,其中,蔬菜产量对出口影响程度最大;我国与出口目的地之间的地理距离、出口目的地的蔬菜产量两个因素与我国蔬菜的出口额呈负相关。【建议】为促进我国蔬菜出口贸易的发展,应提高蔬菜生产的规模经济效应,同时改善蔬菜运输与储藏条件,并不断开拓国际市场,促进我国蔬菜产业协调发展。     

汇率变化对我国农业产业的影响——基于农业部门局部均衡模型

为研究汇率浮动与中国农产品市场波动之间的关系,采用全球农产品市场局部均衡模型,设定5种货币贬值和升值的情景方案,通过静态模拟方法,评估不同货币的汇率变化对中国农业产业的影响。结果显示,人民币贬值时,进口商品变的更加昂贵,进口减少,国内产品的需求增加,刺激国内产出增加。从具体产品来看,人民币贬值对稻谷、小麦、玉米、牛肉、猪肉和奶粉产量的影响较大。当人民币升值,中国农业受到的影响与贬值情况相反。主要农业贸易伙伴国货币汇率变动则首先影响该国产品的进出口量,进而影响产品的世界价格,再通过进出口将价格传导到中国,最终引起中国相关产品的生产、消费和贸易量的变动。中国受到较大影响的是从这些国家进口份额较大的产品,其中欧元、澳元、新西兰元和巴西雷亚尔汇率变动将主要引起中国牛肉、猪肉、奶粉、小麦和大豆进口量和产量的变化。     

Temporal trends in deep ocean Redfield ratios

The Redfield ratio [carbon:nitrogen:phosphorus (C:N:P)] of particle flux to the deep ocean is a key factor in marine biogeochemical cycling. Changes in oceanic carbon sequestration have been linked to variations in the Redfield ratio on geological time scales, but this ratio generally is assumed to be constant with time in the modern ocean. However, deep-water Redfield ratios in the northern hemisphere show evidence for temporal trends over the past five decades. The North Atlantic Ocean exhibits a rising N:P ratio, which may be related to increased deposition of atmospheric nitrous oxides from anthropogenic N emissions. In the North Pacific Ocean, increasing C:N and C:P ratios are accompanied by rising remineralization rates, which suggests intensified export production. Stronger export of carbon in this region may be due to enhanced bioavailability of aeolian iron. These findings imply that the biological part of the marine carbon cycle currently is not in steady state.