丹江口水库叶绿素a浓度的时空特征及影响因子分析

2017年5月—2019年10月,对"南水北调"中线水源水库——丹江口水库库区水体7个监测位点、0～20 m间4个水层的垂向叶绿素a (Chl.a)浓度与水质因子进行了季度性调查,以期了解不同位点、不同水层Chl.a分布的主要驱动因子.结果表明,丹江口水库各位点营养状态指数(TSI)均为中营养化状态.水体Chl.a浓度具有逐年增加的趋势,且极高值有逐渐增加的趋势.营养盐和Chl.a浓度均存在较大的空间异质性,入库区具有较高的总磷和氨氮浓度,汉江库区具有最高的Chl.a浓度,源头污染源控制和监测仍然是丹江口水库管理的重中之重.不同位点Chl.a浓度的驱动因子存在较大差异,汉江入库和大坝区Chl.a浓度分别受到硝态氮和p H的影响,而出水口大坝位点主要受到了水深、水温和氨氮的影响.丹江入库区Chl.a浓度受到了水深、氨氮、总磷和水温的影响,但丹江库区表现出了与其他生态区较大的区别,其Chl.a浓度主要受到水深和有机质输入的影响.因此,对丹江口水库各位点的管理,应该分不同生态区采取针对性的管理措施.本研究旨在为南水北调中线工程可持续的生态调度提供基础生态数据支持,为完善水库水源地的有效管理提供理论支撑.     

菲律宾海北部四国海盆全新世沉积物源分析

对IODP333航次四国海盆北部地区C0011站位表层样品进行粒度和Sr-Nd同位素分析,并与前人发表的邻近海域同位素数据进行比较。经分离自生碳酸盐组分,四国海盆全新世沉积物呈现较好的陆源、火山源二端元组分特征。从地理位置看,四国海盆北部主要物质来源包括伊豆-小笠原海脊火山物质、日本列岛西南部的混合型沉积物以及由西向风或河流入海洋流输送而来的亚洲陆地沉积物,且日本列岛西南部对于该区域物质贡献最大。对四国海盆北部而言,与海盆中部沉积及日本海沉积相比,源自亚洲大陆的碎屑沉积物具有更多的贡献。沉积物中87Sr/86Sr与εNd、平均粒径的负相关关系反映了沉积物中陆源物质的相对贡献按时间顺序呈现增加、减小、增加、减少的多周期变化趋势。     

Magnitude scale structure from filtered broadbandP-wave records

A series of Hokkaido events, recorded by the FBV Broadband Seismograph System at the KHC Seismic Station, is used to study the structure of the earthquake magnitude scale on the basis of maximum velocity amplitudesA _vmax of teleseismicPwaves in different period bands. Amplitude-periodband (APB) diagrams are constructed for each event. According to the shape of the APB diagrams the events investigated can be divided into three types: (a) events with largestA _vmax values in the intermediate period range (periods ofA _vmax from 2.2 to 23 sec), (b) events with largestA _vmax values in the short-period range (periods ofA _vmax from 1 to 2 sec), (c) events exhibiting anomalous APB diagrams. Type (a) events seem to represent the process of wave generation that prevails for shallow earthquakes. Type (b) events approach to explosive-like generation of seismic waves. The nature of the exceptionally occurring type (c) events must be clarified in further investigations. The influence of the type of earthquake on the magnitude values estimated on the basis of standard class A and B (short-period and intermediate-band) seismograms is demonstrated. It appears that for estimating correct values of earthquake magnitudes complementary information on the process of seismic wave generation in the focus is necessary. At teleseismic distances this information can be obtained from either APB diagrams or amplitude spectra ofP waves recorded, e.g., by broadband velocity sensing instruments.     

济阳坳陷四扣洼陷泥质岩裂缝储层预测研究

通过对济阳坳陷四扣洼陷及郭局子地区泥质岩储层的裂缝类型、识别特征进行的研究，认为影响本区裂缝发育程度的因素是区域构造应力及构造部位、岩性、岩相、岩层厚度、埋深及地层压力。并在此基础上建立了地质模型、力学模型和数学模型，运用三维有限元方法对四扣洼陷构造裂缝储层的分布进行了预测。通过预测，提出了研究区裂缝发育在平面上具有不均匀性、连片性差、与断层关系密切的特点，进一步指出了罗42－罗48井区等8个区带为裂缝发育的地区。这项研究不仅对研究区泥岩油气勘探，而且对济阳坳陷及类似地区的泥岩油气勘探有重要指导和启示意义。     

易门式大型铜矿床构造成矿动力学模型

针对金属矿床隐伏矿定位预测的关键问题,在提出构造成矿动力学的分支学术方向的基础上,以易门式大型铜矿床为例,从成矿地质背景、矿田构造、构造地球化学和成矿构造应力场等方面进行构造成矿动力学研究,阐述在构造应力场控制下成矿流体运移和聚集的规律。构造地球化学研究认为,构造地球化学异常反映矿体的原生晕;构造地球化学异常受构造控制,其分带特征可指示成矿流体的流向,并提供矿床成因和隐伏矿(化)体相对埋深的信息。构造应力场的控矿特征主要表现在:构造应力场导致控矿构造的形成,并驱动成矿流体的运移;构造应力场控制了成矿能量场;应力和能量的高值集中区分布特点可反映某些构造型式。在此基础上建立构造成矿动力学模型,概括隐伏矿成矿预测准则,据此提出若干重点找矿靶区和靶位,其中部分靶区得到工程验证,表明构造成矿动力学方法对隐伏矿定位预测和评价具有重要的指导意义。     

Photosynthetic characteristics of dominant tree species and canopy in the broadleaved Korean pine forest of Changbai Mountains

Based on the light-photosynthesis response measurement at leaf level, combined with over-and under-canopy eddy covariance measurements, research on photosynthetic characteristics of single trees and forest canopy was conducted. The relationship between light intensity and photosynthetic rates for leaves and canopy can be well fitted by a non-rectangular hyperbola model. Mongolian oak presented a high light compensation point, L _cp (28 μmol·m^?2·s^?1), a light saturation point L _sp (>1800 μmol·m^?2·s^?1), and a maximal net photosynthetic rate P _max (9.96 μmol·m^?2·s^?1), which suggest that it is a typical heliophilous plant. Mono maple presented the highest apparent quantum efficiency α (0.066) but the lowest, L _cp (16 μmol·m^?2·s^?1), L _sp (≈800 μmol·m^?2·s^?1), and P _max (4.51 μmol·m^?2·s^?1), which suggest that it is heliophilous plant. Korean pine showed the lowest α value but a higher P _max, which suggest that it is a semi-heliophilous plant. At the canopy level, the values of both α and P _max approached the upper limit of reported values in temperate forests, while L _cp was within the lower limit. Canopy photosynthetic characteristics were well consistent with those of leaves. Both showed a high ability to photosynthesize. However, environmental stresses, especially high vapor pressure deficits, could significantly reduce the photosynthetic ability of leaves and canopy.     

Depositional architecture and sequence stratigraphy of the Karoo basin floor to shelf edge succession, Laingsburg depocentre, South Africa

The Laingsburg depocentre of the SW Karoo Basin, South Africa preserves a well-exposed 1200 m thick succession of upper Permian strata that record the early filling of a basin during an icehouse climate. Uniformly fine-grained sandstones were derived from far-field granitic sources, possibly in Patagonia, although the coeval staging and delivery systems are not preserved. Early condensed shallow marine deposits are overlain by distal basin plain siltstone-prone turbidites and volcanic ashes. An order of magnitude increase in siliciclastic input to the basin plain is represented by up to 270 m of siltstone with thin sandstone turbidites (Vischkuil Formation). The upper Vischkuil Formation comprises three depositional sequences, each bounded by a regionally developed zone of soft sediment deformation and associated 20-45 m thick debrite that represent the initiation of a major sand delivery system. The overlying 300 m thick sandy basin-floor fan system (Unit A) is divisible into three composite sequences arranged in a progradational-aggradational-retrogradational stacking pattern, followed by up to 40 m of basin-wide hemipelagic claystone. This claystone contains Interfan A/B, a distributive lobe system that lies 10 m beneath Unit B, a sandstone-dominated succession that averages 150 m thickness and is interpreted to represent a toe of slope channelized lobe system. Unit B and the A/B interfan together comprise 4 depositional sequences in a composite sequence with an overall basinward-stepping stacking pattern, overlain by 30 m of hemipelagic claystone. The overlying 400 m thick submarine slope succession (Fort Brown Formation) is characterized by 10-120 m thick sand-prone to heterolithic packages separated by 30-70 m thick claystone units. On the largest scale the slope stratigraphy is defined by two major cycles interpreted as composite sequence sets. The lower cycle comprises lithostratigraphic Units B/C, C and D while the upper cycle includes lithostratigraphic Units D/E, E and F. In each case a sandy basal composite sequence is represented by an intraslope lobe (Units B/C and D/E respectively). The second composite sequence in each cycle (Units C and E respectively) is characterized by slope channel-levee systems with distributive lobes 20-30 km down dip. The uppermost composite sequence in each cycle (Units D and F respectively) are characterised by deeply entrenched slope valley systems. Most composite sequences comprise three sequences separated by thin (<5 m thick) claystones. Architectural style is similar at individual sequence scale for comparable positions within each composite sequence set and each composite sequence. The main control on stratigraphic development is interpreted as late icehouse glacio-eustasy but along-strike changes associated with changing shelf edge delivery systems and variable bathymetry due to differential substrate compaction complicate the resultant stratigraphy.     

Assessment and zonation of storm surge hazards in the coastal areas of China

Natural Hazards - Coastal inundation due to storm tides is computed using ADvanced CIRCulation (ADCIRC) model along the east coast of India. Inland inundation due to storm tides is calculated every...     

南极半岛邻近海域夏季POC分布特征及其影响因素

海水中的颗粒有机碳(POC)与生物的生命过程、初级生产力关系密切,是海洋食物链中重要的物质基础和能量来源,因此POC的分布特征可以有效反映其生物地球化学环境。利用中国第33次南极考察期间(2016年12月至2017年1月)在南极半岛邻近海域采集的海水颗粒物样品,研究POC的空间分布特征及其影响因素。结果表明,斯科舍海0—200 m的POC浓度范围为7.44—193.52μg·L~(-1),平均浓度为(48.84±35.09)μg·L~(-1);南斯科舍海岭0—200 m的POC浓度范围为9.13—62.17μg·L~(-1),平均浓度为(29.76±14.12)μg·L~(-1);鲍威尔海盆0—200 m的POC浓度范围为5.87—270.72μg·L~(-1),平均浓度为(48.57±38.92)μg·L~(-1)。表层POC高值出现在斯科舍海区和鲍威尔海盆区,而低值出现在海岭区,与叶绿素a(Chla)的变化趋势一致,与营养盐的变化趋势相反。垂向分布上,各个区域POC平均浓度随深度的增加而减少,鲍威尔海盆和斯科舍海POC最高值都出现在25 m层。分析结果表明光合浮游植物是研究海域POC的主要来源, POC的主要影响因素为温度、水团混合以及海冰环境。斯科舍海与鲍威尔海盆整体非生命POC占比高,可能是由于高磷虾生物量、海冰碎屑以及陆源输入的干扰;南斯科舍海岭整体非生命POC占比低。