西北太平洋热带云团发展与两类El Nio事件的联系

利用1982—2009年全球热带云团数据集、NCEP/NCAR再分析资料和英国Hadley中心海温资料,并引入热带云团生成率(Genesis Productivity,GP)来分析EP(Eastern Pacific)El Nio和CP(Central Pacific)El Nio事件与西北太平洋热带云团发展的相关性。研究表明,1)夏秋两季GP与Nio3指数在东南区(SE)均为显著正相关,在西南区(SW)仅秋季呈显著正相关;GP与EMI(El Nio Modoki Index)指数在夏季SE区域为显著正相关,在秋季南中国海(South China Sea,SCS)区呈负相关。2)在EP El Nio年,夏季SE区域的GP增大与低层涡度、高层散度以及低层相对湿度的相对增大一致。夏季SW区域与秋季SE区域的GP增大与有利的高低空配置相关,La Nia年则与之相反。3)在CP El Nio年,夏季SE区域的GP增大伴随着低层涡度和高层散度的增加,同时与充足的水汽及弱风切变相吻合;而秋季SCS区域的GP下降源于正涡度带、正散度带以及水汽带的东移。     

The effect of river-delta system on the formation of the source rocks in the Baiyun Sag,Pearl River Mouth Basin

Source rock formation influenced by river-delta system, especially in continental margin basins, is still poorly understood. This article aimed to reveal the effect of river-delta system on the formation of the source rock by taking the Baiyun Sag of the Pearl River Mouth Basin for example. Paleo-Pearl River began to develop since the Enping Formation, providing abundant organic matter beneficial for the formation of the source rocks in the Baiyun Sag. The main controlling factor of source rock formation in the Baiyun Sag is terrestrial organic matter supply rather than the paleoproductivity or redox conditions. Low Al/Ti and P/Ti ratios suggest low marine productivity, which may be associated with a large number of terrigenous detritus input, occupying about 43.04%–94.91%. There is a positive correlation between the oleanane/C₃₀hopane ratio and the TOC value, showing that terrigenous organic matter controls the source rock formation. The size of the delta below Pearl River estuary determines the extent of terrestrial organic matter supply. Source rocks with high organic matter abundance mainly formed in delta environment, and those in neritic environment in Enping and Zhuhai Formations also have high TOC values as a result of adequate terrestrial organic matter supply.     

连续两次台风过境对东海北部水环境及初级生产力的影响

台风是影响东海最严重的自然灾害之一。本文在现场观测基础上,结合遥感与模型数据,研究了连续两个台风过境对东海北部水环境及初级生产力的影响。研究结果表明:连续两个台风过境情况下,虽然前面台风有助于后续台风对海洋上层进行垂直混合作用,但它对后续台风过后海洋表层温度(SST)的降低以及初级生产力的增加却起到了削弱作用;除了加强垂向混合过程,台风也可以改变海洋上层的平流输运过程,受此影响,部分海区上层温度、盐度以及叶绿素在台风后重新分布;台风对海区次表层叶绿素浓度的改变程度明显高于表层,某些站位次表层叶绿素最大值(SCM)在台风刚过后被破坏,一段时间后SCM又重新出现,而且层内叶绿素浓度远高于台风前水平。     

Species composition,abundance and biomass of microphytoplankton in the KwaZulu-Natal Bight on the east coast of South Africa

Nearshore marine environments are influenced by an array of variables that can either be land-derived or of marine origin, and nearshore phytoplankton communities may differ in their taxonomic composition and biomass in response to such variables. The KwaZulu-Natal Bight (hereafter referred to as ‘the bight’) is an oligo-mesotrophic, nearshore oceanic environment, that is influenced by both terrestrial run-off and upwelling. A microphytoplankton survey of the bight conducted over several stations and depths and two seasons was conducted in order to ascertain species composition, abundance and biomass. Microphytoplankton abundance was generally low (a maximum of 180 000 cells l–1 was recorded) but differed considerably between sites and seasons. A total of 99 taxa of mainly Bacillariophyceae and some Dinophyceae, Prymnesiophyceae and Cyanophyceae were identified in the present study. In the central bight, higher abundance and biomass were measured in February (wet season), which may be a possible consequence of terrestrial nutrient inputs. In the northern and southern bight we measured higher abundance and biomass in August (dry season). Upwelling was not detected during the study, but an influence of terrestrial nutrient sources was detected at the coastal stations. Turbid conditions were specific to the site near the Thukela River mouth and possibly influenced abundance, biomass and species composition at this site. Historic data on microphytoplankton composition are scarce, but comparisons with surveys from the 1960s reveal that around 60% of the common diatoms recorded then also occurred in the present study. Small taxa [20–200 µm] dominated the microphytoplankton community. Community composition was fairly uniform throughout the bight in both seasons, dominated in general by Chaetoceros species, and on occasion co-dominated by Thalassionema nitzschioides and Dactyliosolen fragilissimus.     

Determinants of microregional agricultural labour productivity – Evidence from Czechia

In this paper we aimed to explain differences in agricultural labour productivity at microregional level. We tested the effects of three major independent variables – farmland fragmentation, urbanization economies and farm size structure with particular emphasis on the relationship between land-use fragmentation and microregional differences in agricultural labour productivity. Our principal question therefore was if higher agricultural labour productivity at microregional level is associated with internal scale economies resulting from large average farm size (in terms of employment), proximity to large cities as a proxy for urbanization economies and lower levels of land-use fragmentation. We also asked if productivity gains from large average size of plots is higher than potential losses resulting from land tenure (tenants are generally less productive than farmland owners). Drawing on a case study of Czechia – a country with extremely fragmented farmland ownership, but the largest average size of plots in the EU and a strong role of farmland rental market – we confirmed our initial expectation that land-use fragmentation affects negatively microregional agricultural labour productivity. Larger average size of plots is positively related to microregional agricultural labour productivity despite potentially negative effects of land tenure. At the same time, no significant effects of urbanization economies and farm size structure were documented.     

基于DEA-Malmquist模型的唐山市工业经济与能源全要素生产率分析

以唐山市34个工业行业的面板数据为基础,选择DEA和Malmquist指数模型,对1992~2012年全要素经济生产率、2000~2012年全要素能源生产率及其分解结果进行了分析,并对全要素经济生产率、全要素能源生产率分别进行了影响因素分析。结果发现：研究期内,全要素经济生产率、全要素能源生产率均有所提高,其中技术进步发挥了最主要作用。总体上,经济、能源的TFP指数均在2010年表现最优。分行业看,唐山市的传统优势产业的经济、能源TFP指数增长较快,这对唐山未来产业转型和重组产生了较大阻力,但是也显示出能源集约化程度有所提高。从根本上看,产业结构的不合理不仅束缚了经济、能源效率的提高,且连带影响了对外开放水平的进步及能源结构的优化。通过对唐山市工业行业经济、能源的静态与动态效率分析,并进行影响因素分析,可判定唐山工业发展的质量及各行业的发展差异,为区域进一步转型发展提供理论依据。     

Temporal and Morphological Variations of Growth in a Natural Stand of Posidonia oceanica (L.) Delile*

Abstract. Growth of Posidonia oceanica (L.) DELILE was studied in a natural stand in 4 m depth at Ischia (Gulf of Naples). Renewal and growth of leaves was continuous throughout the year but showed strong seasonal modulation. The major factor for individual leaf growth as well as for the seasonal aspects of the entire foliage is seasonal modulation of leaf appearance rather than of leaf growth. Leaf area index varied between 2 nm² m^-2 in autumn and 6 m² m^-2 in late summer. Annual production is estimated to be 613 g dw m^-2 for leaf blades, 54 g dw m^-2 for leaf sheaths, and 27 g dw m^-2 for rhizomes. Rhizome production is highly different between the primary and the secondary growth axis (274 versus 30 mg dw -shoot^-1 y^-1 respectively) in plagiotrope growth. Both foliage and rhizome growth are positively correlated with leaf width.     

Sedimentary records of multidecadal-scale variability of diatom productivity in the Bungo Channel, Japan, associated with the Pacific Decadal Oscillation

In order to examine the responses of primary productivity in the southern coastal sea of Japan to the Pacific Decadal Oscillation (PDO) in the 20th century, sedimentary records of diatom productivity (diatom valve fluxes) were reconstructed using core samples from the Bungo Channel (BC) in southwest Japan. The record of the Thalassionema spp. flux—the best index of fall primary productivity in the BC—indicated a multidecadal-scale duration with a low flux (1943–1982) and those with a high flux (1913–1943 and 1982–2001); apparent shifts were recognized in 1943 and 1982. The shift in 1982 was also recognized in the flux records of other early summer to fall predominant genera in the BC and, previously, in the biogenic silica records from a broad region of the southeast BC. This indicates that in our records, this shift reflects a general trend in the primary production in the southeast BC. A comparison among the Thalassionema spp. flux records, meteorological data from an observatory adjacent to the core site, and the PDO index showed that the flux records were more similar to the PDO index than the other meteorological records, which suggests that the multidecadal-scale variability of the BC primary productivity may be associated with some marine-derived forcing. The bottom intrusions of nutrient-rich water that upwelled from the shelf slope into the BC, the axis movement or the transport of the Kuroshio Current off the BC, and a basin-scale wind stress in the North Pacific might play an important role in this forcing and mediate between the BC primary productivity and the PDO.     

Carbon and nitrogen primary productivity in three North Carolina estuaries

Uptake of inorganic carbon and ammonium by the plankton community of three North Carolina estuaries was measured using ¹⁴C and ¹⁵N isotope methods. At 0% light, C appeared to be lost via respiration, and at increasing light levels uptake of inorganic carbon increased linearly, saturated (mean I_k = 358±30 μEin m⁻² s⁻¹), and frequently showed inhibition at the highest light intensities. At 0% light NH₄⁺ uptake was significantly greater than zero and was frequently equivalent to uptake in the light (light independent); at increasing light levels NH₄⁺ uptake saturated (mean I_k = 172±44 μEin m⁻² s⁻¹) and frequently indicated strong inhibition. Light-saturated uptake rates of inorganic carbon and NH₄⁺ were a function of chlorophyll a (r² = 0·7−0·9); average assimilation numbers were 625 nmol CO₂ (μg chl. a)⁻¹ h⁻¹ and 12·9 nmol NH₄⁺ (μg chl. a)⁻¹ h⁻¹ and were positively correlated with temperature (r² = 0·3−0·7). The ratio of dark to light-saturated NH₄⁺ uptake tended to be near 1·0 for large algal populations at low NH₄⁺ concentrations, indicating near light independence of uptake; whereas the ratio was lower for the opposite conditions. These data are interpreted as indicative of nitrogen stress, and it is suggested that uptake of NH₄⁺ deep in the euphotic zone and at night are mechanisms for balancing the C:N of cellular pools. A 24-h study using summed short-term incubations confirmed this; the cumulative C:N of CO₂ and NH₄⁺ uptake during the daylight period was 10–20, whereas over the 24-h period the ratio was 6 due to dark NH₄⁺ uptake. Annual carbon and nitrogen primary productivity were respectively estimated as 24 and 4·0 mol m⁻² year⁻¹ for the South River estuary, 42 and 7·3 mol m⁻² year⁻¹ for the Neuse River estuary, and 9·6 and 1·6 mol m⁻² year⁻¹ for the Newport River estuary.     

Station Papa Time Series: Insights into Ecosystem Dynamics

The Northeast Pacific has one of the longest time series of any open ocean station, primarily as a result of the weathership station at Station P from the 1950s to 1981. This review summarizes our understanding of the plankton ecosystem for this station and examines interannual variability for the primary producers. The weathership era characterized a period of high temporal sampling resolution with a limited number of parameters being measured. In contrast, the post-weathership period focussed on seasonal sampling (usually three times per year), but a wider range of parameters were measured and sediment traps were deployed to estimate carbon and opal flux rates. The mixed layer depth is shallow compared to the Atlantic Ocean, ranging from 40 to 120 m in late summer and winter respectively. Nitrate, silicate and phosphate are saturating year round with only a few exceptions in the 1970s. Winter and summer Si:N ratios are the same (1.5:1). Ammonium and urea are 0.5 uM in winter and near detection limits (∼0.1 uM) in late summer. Iron is limiting (∼0.05 nM) in late spring and summer for the growth of large diatoms, but iron is co-limiting with irradiance in winter. Chlorophyll and primary productivity are low and show little seasonal variation (about 2 times). Summer chl is about 20 mg m⁻² while primary productivity ranges from 400–850 mg C m⁻²d⁻¹. The f-ratio of 0.25 does not vary with seasons and indicates that primary productivity is fueled by regenerated nitrogen (e.g. NH₄ and urea). Small cells (<5 um) are normally abundant and they utilize regenerated nitrogen produced by the micrograzers; they do not appear to be Fe-limited, but rather controlled by the micrograzers. Shipboard carboy experiments indicate that large diatoms become dominant when iron is added. Therefore top down control is exerted by the micrograzers on the small cells, while there is bottom up control of the large phytoplankton due to low Fe concentrations. This revised version was published online in August 2006 with corrections to the Cover Date.