海南省海水鱼养殖产业现状调研与对策研究

文章基于“结构-行为-绩效”（SCP）范式,从市场结构、市场行为和市场绩效3个方面分析海南省的海水鱼养殖产业。发现：海水鱼养殖业属于原子型市场结构,市场集中度较低,龙头企业竞争力不足;总体进入壁垒较低,市场进入难度较小;种苗产业链分工和定价随机性强,鱼卵价格出现经常性短期波动;海水养殖业资源配置效率较低,许多企业面临环保督察、经营管理、人力资源等诸多危机,产业技术进步贡献度不足。因此,提出如下建议：海南海水鱼养殖业需要在兼顾生态文明建设的前提下,政府需要制定长远的渔业发展规划;加快推进行业的分工与专业化的生产;通过兼并、强强联合加快推进规模经济,进一步提高产品附加值,提高产业综合竞争力。     

The sediment record of the past 200 years in a Swiss high-alpine lake: Hagelseewli (2339 m a.s.l.)

Sediment cores spanning the last two centuries were taken in Hagelseewli, a high-elevation lake in the Swiss Alps. Contiguous 0.5 cm samples were analysed for biological remains, including diatoms, chironomids, cladocera, chrysophyte cysts, and fossil pigments. In addition, sedimentological and geochemical variables such as loss-on-ignition, total carbon, nitrogen, sulphur, grain-size and magnetic mineralogy were determined. The results of these analyses were compared to a long instrumental air temperature record that was adapted to the elevation of Hagelseewli by applying mean monthly lapse rates.During much of the time, the lake is in the shadow of a high cliff to the south, so that the lake is ice-covered during much of the year and thus decoupled from climatic forcing. Lake biology is therefore influenced more by the duration of ice-cover than by direct temperature effects during the short open-water season. Long periods of ice-cover result in anoxic water conditions and dissolution of authigenic calcites, leading to carbonate-free sediments.The diversity of chironomid and cladoceran assemblages is extremely low, whereas that of diatom and chrysophyte cyst assemblages is much higher. Weak correlations were observed between the diatom and chrysophyte cyst assemblages on the one hand and summer or autumn air temperatures on the other, but the proportion of variance explained is low, so that air temperature alone cannot account for the degree of variation observed in the paleolimnological record.Analyses of mineral magnetic parameters, spheroidal carbonaceous particles and lead suggest that atmospheric pollution has had a significant effect on the sediments of Hagelseewli, but little effect on the water quality as reflected in the lake biota.     

黄河中上游季节内强降水的时间非均匀性特征及其对大气环流的响应

应用1960-2008年5-10月黄河中上游流域66个气象台站降水资料和美国环境预测中心及大气研究中心（NCEP/NCAR）再分析资料,综合气候分区及地表水系分布情况,将黄河中上游流域分为高原区、干旱区、季风影响区,以强降水集中度（SCD）和强降水集中期（SCP）来表征强降水的非均匀性特征,并对SCP异常年份的强降水的变化特征及环流形式进行分析。结果表明：①黄河中上游流域大部分地区强降水依赖化的特征显著,强降水分布最为均匀的地区为秦岭北麓及山西南部,降水最为集中的地区为河套地区及陕北等地。②在黄河中上游流域,3个区强降水平均发生的时间先后顺序为季风影响区最晚、干旱区次之、高原区最早,且均相差一候;黄河流域季风影响区的南部渭河、泾河、洛河等处及青藏高原东部的兰州附近为大的SCP变率区,强降水发生的时间变动较大,鄂尔多斯高原东北部为小的SCP变率区,强降水发生时间稳定;干旱区与季风影响区汛期SCP于20世纪90年代初期发生由大变小的显著性突变,且干旱区突变提前于季风影响区。③干旱区汛期SCP异常年份的高空环流显示,当西太平洋副高北抬至30°N以北120°E左右、南亚高压维持在30°N左右120°E以东时,若两高压“同进同退”(“同向而进、背向而退”),则强降水发生在汛期(7月中旬-8月下旬)后(前)期。黄河流域季风影响区强降水异常年份的高空环流显示,当西太平洋副热带高压维持在26°-30°N、120°E左右,南亚高压维持在30°N左右、120°E以西时,若两高压“同进同退”(“同向而进、背向而退”),则强降水发生在汛期后(前)期。     

Active diapirism and slope steepening,northern gulf of Mexico continental slope

Abstract

Large diapiric and nondiapiric masses of Jurassic salt and Tertiary shale underlie the northern Gulf of Mexico continental slope and adjacent outer continental shelf. These masses show evidence of being structurally active at present and in the very recent geologic past. Local steepening of the sea floor in response to the vertical growth of these structures is a serious concern to those involved in the site selection and the construction of future oil and gas production and transportation facilities in this frontier petroleum province.

The seabed of the northern Gulf slope is hummocky and consists of many hillocks, knolls, and ridges interspersed by topographic depressions and canyon systems. Topographic highs and lows relate respectively to vertical diapiric growth and to withdrawal of large volumes of salt and shale. Topographic highs vary considerably in shape and size, but all have very limited areas of nearly flat sea floor. Intraslope topographic lows consist of three principal types: (1) remnants of submarine canyons blocked by diapiric uplift that terminated active downslope sediment transport common during stages of low sea level; (2) closed depressions formed by subsidence in response to salt and shale withdrawal and flow into surrounding diapiric uplifts; and (3) small collapse basins formed by faulting in strata arched over structural crests of diapirs.

Distribution patterns of both diapiric features and sediment accumulations on the slope are the result of the complex relationship that exists between sediment loading and diapirism. Diapiric activity is proportional to the thickness of salt or underconsolidated shale available for mobilization, and to the sedimentary load distribution on these highly plastic deposits. Variations in overburden load, in turn, are dependent on rates, volumes, and bulk densities of depo‐sitional influx; proximity to sources of supply, erosion, and distribution of sediments; and topographic control of sediment accumulation. Sediment capture in diapirically controlled interdomal basins and canyon systems localizes overburden load, thus inducing further diapiric growth, and complex structural and stratigraphic patterns are induced throughout the continental slope region.

Drill cores in the slope province indicate that most of the slope sediments are fine‐grained muds; appreciable quantities of sand‐size sediment are present principally in canyon axes. Turbidite sand layers drilled on a topographic high adjacent to the Gyre Basin reflect uplift far above their original deposition level, and calculations yield rates of uplift that average 2 to 4 m per 100 years. Seismic reflection profiles provide considerable evidence of “fresh”; slumps and ero‐sional surfaces on the flanks of many topographic highs not yet blanketed by a veneer of young sediments. This evidence thus supports our conclusion that the present continental slope region of the northern Gulf of Mexico is undergoing active diapirism and consequent slope steepening. Because most of the sediment on the flanks of diapiric structures consists of underconsolidated muds, slumping will take place regularly in response to further diapiric movement.     

Evaluation of Undrained Shear Strength and Consolidation Characteristics of Disturbed Marine Sedimentary Clay due to SCP Installation

The behaviors of the marine sedimentary ground improved by sand compaction pile (SCP) method are analyzed. To do this, the results of upheaval characteristics of the sea floor, undrained shear strength, and horizontal consolidation coefficient (consolidation) are investigated. Due to SCP installation on ground, as thickness of a soft clay layer increases, upheaval height increases and upheaval angle decreases. Undrained shear strength of disturbed ground due to SCP construction decreases in early stage after completion of construction, but it shows a trend of recovering as months elapse. As the result of piezocone penetration dissipation tests, consolidation delay phenomenon by the disturbance due to SCP installation clearly is identified and its degree is dependent on the replacement area ratio of SCP and the location of ground.     

网络视角下旅游产业集群差异及成因——基于多案例的比较研究

旅游产业集群具有网络属性,从网络角度研究产业集群已成为当前研究的趋势。但学术界大部分关于旅游产业集群的研究都是移植产业集群的理论成果,鲜有比较视野下的旅游产业集群差异及其成因分析。从旅游产业集群的网络化特征出发,以产业组织理论的SCP范式为分析框架,选择平遥古城旅游产业集群、剑门蜀道旅游产业集群、黄陂乡村旅游产业集群、杭州西湖国际旅游综合体4个典型案例为研究对象,运用分析归纳法得出不同类型旅游产业集群的网络结构、网络行为和网络绩效间的关系和差异,并解释了造成集群绩效差异的原因。     

赣北黄茅潭近代湖泊~(137)Cs蓄积特点、SCP计数和事件性沉积及其对~(210)Pb计年的矫正

对赣北黄茅潭近代湖泊沉积岩芯进行了~(137)Cs、~(210)Pb测试和SCP(球状碳粒)计数分析,阐述了~(137)Cs蓄积特征,结合SCP计数、粒度指标及降水记录厘定了一些事件性沉积层位。研究表明,1986年前后是沉积环境中~(137)Cs行为的转折点;在这之前,~(137)Cs以大气散落为主,其蓄积行为大致与降水存在正相关关系,在这之后,~(137)Cs以流域侵蚀为主,其蓄积行为与降水呈负相关关系。1953—1954年、1974—1975年、1998—1999年,流域降水丰沛,相应沉积层位~(137)Cs比活度低,这与流域强烈侵蚀稀释了进入湖泊的~(137)Cs有关。1963—1964年沉积层位~(137)Cs蓄积峰稳定而显著,与高通量的大气散落有关,也与当时降水量低,大雨、暴雨次数少,流域侵蚀强度低造成较低的沉积速率等密切相关,是可靠的定年时标。1986年存在同样的气候环境特点,其蓄积峰可能也是存在的,但需要进一步确认。基于~(210)Pb方法,利用多种计年模式计算了沉积岩芯的年代,发现与这些事件性沉积层位具有较大差异。研究认为,在长江中游这种降水高、流域侵蚀强度高的较为复杂的沉积环境中,~(210)Pb计年存在较大误差。复杂沉积环境中近代沉积的定年,有必要深度挖掘~(137)Cs环境行为,在全面阐述其蓄积特点的基础上,辅以SCP计数、粒度指标及降水等识别事件性沉积层位,矫正~(210)Pb计年,是精确建立近代沉积时标的必要方法。     

金枪鱼渔业国际市场结构成因分析及对我国的启示

金枪鱼渔业作为远洋渔业和海洋经济的重要组成部分,其发展受到各远洋渔业大国的高度重视和大力扶持。文章基于SCP分析范式,从市场结构、市场行为及市场绩效3个范畴研究金枪鱼渔业产业组织的结构特征,分析影响金枪鱼渔业市场结构的因素,探究市场结构、市场行为和市场绩效三者的关系。研究发现:金枪鱼国际生产和贸易垄断集中程度降低,市场竞争的有效性不断加强;金枪鱼的市场结构受到市场集中度、产品差别化,进入和退出壁垒的影响;金枪鱼渔业市场结构、市场行为和市场绩效之间存在相互影响关系。文章最后为我国发展金枪鱼渔业,提升国际竞争力提出了发挥渔业管理组织牵头作用,共同维护金枪鱼市场有效竞争;积极促进企业发展,提高生产研发能力,立足国际市场;创造良好国际环境,切实为金枪鱼渔业发展保驾护航等建议。     

Sediment Stratigraphy and Heavy Metal Fluxes to Reservoirs in the Southern Pennine Uplands, UK

Reservoir sediments are rarely used as environmental archives because of the potential for sediment disturbance by fluctuating water levels. However, rapid rates of sedimentation, proximity to urban centres and often the existence of management records, may make them potentially important resources for reconstructing recent, anthropogenically-derived environmental change. This project assesses the potential of reservoir sedimentary records for reconstructing past atmospheric and drainage basin fluxes of heavy metals (manganese, iron, nickel, copper, zinc and lead) in the southern Pennines, UK. Five reservoirs were selected on the basis of management history and drainage basin characteristics. Multi-parameter analysis showed sediments to be replicable across the ȁ8accumulating zone’ with reasonably consistent rates of sedimentation. Water level fluctuations were not found to detrimentally affect sediment records in the deepwater area of the reservoirs. In fact, spheroidal carbonaceous particle (SCP) profiles show trends in inputs that closely reflect major changes in industrialisation, indicating the reservoir sediments to be excellent records of particulate inputs. Only lead (Pb) and zinc (Zn) were significantly enriched in the reservoir sediment in comparison to background levels. Manganese (Mn), iron (Fe) and to a limited degree, copper (Cu), appeared to be affected by post-deposition mobility. Preliminary calculations of Pb fluxes indicate that over 80% of the current Pb input to the reservoirs is from Pb deposited onto drainage basin soils in the past, rather than from direct atmospheric deposition or natural background inputs. In Howden reservoir, for example, the total Pb flux to deepwater sediment cores in 2000 was 119 mg m⁻² a⁻¹. Of this, an estimated 99 mg m⁻² a⁻¹ was from anthropogenically-derived Pb, initially deposited onto drainage basin soils and subsequently entering the reservoir via erosion and leaching processes. There is, therefore, no indication that the flux of Pb to the aquatic system is declining in response to reductions in Pb deposition. The ecotoxicological effects of the high and continuing Pb flux to these reservoirs, despite recent decreases in atmospheric deposition, is an area requiring further investigation.     

Galactic vs. extragalactic origin of the peculiar transient SCP 06F6

We study four scenarios for the SCP 06F6 transient event that was announced recently. Some of these were previously briefly discussed as plausible models for SCP 06F6, in particular with the claimed detection of a z=0.143 cosmological redshift of a Swan spectrum of a carbon rich envelope. We adopt this value of z for extragalactic scenarios. We cannot rule out any of these models, but can rank them from most to least preferred. Our favorite model is a tidal disruption of a CO white dwarf (WD) by an intermediate-mass black hole (IMBH). To account for the properties of the SCP 06F6 event, we have to assume the presence of a strong disk wind that was not included in previous numerical simulations. If the IMBH is the central BH of a galaxy, this explains the non-detection of a bright galaxy in the direction of SCP 06F6. Our second favorite scenario is a type Ia-like SN that exploded inside the dense wind of a carbon star. The carbon star is the donor star of the exploded WD. Our third favorite model is a Galactic source of an asteroid that collided with a WD. Such a scenario was discussed in the past as the source of dusty disks around WDs, but no predictions exist regarding the appearance of such an event. Our least favorite model is of a core collapse SN. The only way we can account for the properties of SCP 06F6 with a core collapse SN is if we assume the occurrence of a rare type of binary interaction.