Characteristics and regional classification of the copepod community in Ariake Bay with note on comparison with 3 decades ago

Ariake Bay, Kyushu Island, has recently exhibited environmental degradation in the form of red tides and anoxic bottom water. To determine the characteristics and regional classification of the copepod community, zooplankton surveys were made throughout the bay in three cruises each in October 2004, January 2005 and March 2009 by vertical tows of a 0.1-mm-mesh plankton net. Oithona davisae was the most abundant in January and March, and Microsetella norvegica in October. Cluster analysis revealed that the copepod community from each cruise was generally separated into the inner to eastern-middle region and the western-middle to mouth region. A SIMPER analysis revealed that dissimilarity between the groups and similarity within each group were mainly due to the dominant species, but the similarities within the outer-region group in January and March were mostly contributed by Paracalanus parvus s.l. A non-metric multidimensional scaling with bubble plots of environmental variables and a BIOENV analysis showed that transparency was more different between the two groups than temperature and salinity. As compared with two similarly sized, eutrophic bays (Tokyo and Osaka Bays), Ariake Bay differs from Tokyo Bay in the dominance of M. norvegica and from Osaka Bay in the high abundance of O. davisae even in the colder season. The dominant species and the regional classification of the copepod community in the bay were similar to those in the studies in the 1970s, suggesting that the copepod community has not notably changed during the last 3 decades.     

Importance of intracellular Fe pools on growth of marine diatoms by using unialgal cultures and on the Oyashio region phytoplankton community during spring

We report on the ability for luxury Fe uptake and the potential for growth utilizing intracellular Fe pools for 4 coastal centric diatom isolates and in situ phytoplankton assemblages, mainly composed of diatoms. Iron uptake of the diatom isolates and natural phytoplankton assemblages in the Oyashio region during spring blooms were prevented by adding hydroxamate siderophore desferrioxamine B (DFB). After the addition of DFB, intracellular Fe in the diatom isolates supported 2.4–4.2 cell divisions with 1.2–2.6 Chl a doublings. The intracellular Fe was primarily used for cell generation rather than Chl a production, leading to a reduction in the Chl a cell quota in the Fe-starved cells with time. The metabolic properties of the Fe-starved cells with their cell morphologies were different among species or genera. An on-deck incubation experiment also exhibited 1.9 cell divisions and 0.81 Chl a doublings of phytoplankton after the addition of DFB, also indicating the preference of cell generation over Chl a production. A decrease in the level of cellular Chl a, a main light-harvesting pigment in Fe-starved diatoms, may become a superior survival strategy to protect the cells from high irradiance that can cause photo-oxidative damages through photosynthesis. Such relatively low-Fe with high-light conditions could often occur in surface waters of the Oyashio region from spring to summer.     

InSAR detection of residual settlement of an ocean reclamation engineering project: a case study of Hong Kong International Airport

Man-made land or islands that are reclaimed from the sea are suitable for building airports, harbors, and industry parks for material transportation because of their broad air and land spaces. However, the reclaimed foundation settlement process is of public concern, including the continuous impact of ocean processes on its stability. The majority of the buildings and facilities of Hong Kong International Airport (HKIA) are built on a reclaimed foundation. The reclaimed foundation has been in residual settlement since completion of the filling project in 1994. In this study, we use persistent scatterer interferometry (PSI) and ENVISAT (European Satellite) advanced synthetic aperture radar (ASAR) data to detect the residual settlement rates from 19 April 2006 to 9 January 2008. We use ground truth data to develop empirical correction models for correcting systematic biases in the ASAR PSI-detected settlement rates. The corrected data follow the Lorentz distribution well, implying that the residual settlement process is dominated by two modes or categories of settlement rates. The first category represents a relatively stable state and the second category represents a continuous settlement state. A ground settlement rate map of HKIA shows that an area of the Passenger Terminal Building and an area of the Southern Runway are two relatively stable areas. There are two major continuous settlement areas. One covers the airport Midfield. Another is along the coastline, implying that attention should be paid to impacts of ocean processes on the stability of airport foundations.     

黄海、渤海铅-210沉积速率的分布特征及其影响因素

对黄海、渤海17个箱式柱样进行了210Pb放射性活度测定,计算了近百年来210Pb沉积速率,并结合前人资料对黄海、渤海区210Pb沉积速率的空间分布特征及其影响因素进行探讨,结果表明,黄河口附近站位沉积速率最高(＞2 cm/a),而在渤海中部、渤海湾以及山东半岛沿岸的站位沉积速率较小(≈0.5 cm/a),部分站位沉积...     

Contamination and distribution of heavy metals in urban and suburban soils in Zhangzhou City,Fujian, China

The urban environment is of growing concern as its continued population increase in China. Due to the urbanization and industrialization, heavy metals have been continuously discharged into the soil recently, and creating the anthropogenic contamination. This study investigated heavy metals contamination in urban and suburban soils in Zhangzhou City, Fujian, China. Multivariate analysis and geographical information system technology were employed in source identification and contamination assessment of heavy metals in the city soils. The survey results indicated that the urban soils were contaminated by heavy metals, especially by Hg, Cd and Pb. The multivariate analysis demonstrated that the distribution of Cu, Zn, Cr and Ni was controlled by pedogenesis, Cd and Pb had been disturbed by industrialization in some urban locations, and Hg was mainly influenced by the hot-spring in some urban park sites. The distribution of heavy metals and soil pollution index suggested the soils of Zhangzhou City have been affected by human activities.     

Fractionation characteristics of rare earth elements (REEs) linked with secondary Fe,Mn, and Al minerals in soils

Soil secondary minerals are important scavengers of rare earth elements (REEs) in soils and thus affect geochemical behavior and occurrence of REEs. The fractionation of REEs is a common geochemical phenomenon in soils but has received little attention, especially fractionation induced by secondary minerals. In this study, REEs (La to Lu and Y) associated with soil-abundant secondary minerals Fe-, Al-, and Mn-oxides in 196 soil samples were investigated to explore the fractionation and anomalies of REEs related to the minerals. The results show right-inclined chondrite-normalized REE patterns for La–Lu in soils subjected to total soil digestion and partial soil extraction. Light REEs (LREEs) enrichment features were negatively correlated with a Eu anomaly and positively correlated with a Ce anomaly. The fractionation between LREEs and heavy REEs (HREEs) was attributed to the high adsorption affinity of LREEs to secondary minerals and the preferred activation/leaching of HREEs. The substantial fractions of REEs in soils extracted by oxalate and Dithionite-Citrate-Bicarbonate buffer solutions were labile (10 %–30 %), which were similar to the mass fraction of Fe (10 %–20 %). Furthermore, Eu was found to be more mobile than the other REEs in the soils, whereas Ce was less mobile. These results add to our understanding of the distribution and geochemical behavior of REEs in soils, and also help to deduce the conditions of soil formation from REE fractionation.     

Subduction-related mafic to felsic magmatism in the Malayer–Boroujerd plutonic complex,western Iran

The Malayer–Boroujerd plutonic complex (MBPC) in western Iran, consists of a portion of a magmatic arc built by the northeast verging subduction of the Neo-Tethys plate beneath the Central Iranian Microcontinent (CIMC). Middle Jurassic-aged felsic magmatic activity in MBPC is manifested by I-type and S-type granites. The mafic rocks include gabbroic intrusions and dykes and intermediate rocks are dioritic dykes and minor intrusions, as well as mafic microgranular enclaves (MMEs). MBPC Jurassic-aged rocks exhibit arc-like geochemical signatures, as they are LILE- and LREE-enriched and HFSE- and HREE-depleted and display negative Nb–Ta anomalies. The gabbro dykes and intrusions originated from metasomatically enriched garnet-spinel lherzolite [Degree of melting (f_mel) ~ 15%] and exhibit negative Nd and positive to slightly negative ε_Hf(T) (+ 3.0 to ? 1.6). The data reveal that evolution of Middle Jurassic magmatism occurred in two stages: (1) deep mantle-crust interplay zone and (2) the shallow level upper crustal magma chamber. The geochemical and isotopic data, as well as trace element modeling, indicate the parent magma for the MBPC S-type granites are products of upper crustal greywacke (f_mel: 0.2), while I-type granites formed by partial melting of amphibolitic lower crust (f_mel: 0.25) and mixing with upper crustal greywacke melt in a shallow level magma chamber [Degree of mixing (f_mix): 0.3]. Mixing between andesitic melt leaving behind a refractory dense cumulates during partial crystallization of mantle-derived magma and lower crustal partial melt most likely produced MMEs (f_mix: 0.2). However, enriched and moderately variable ε_Nd(T) (? 3.21 to ? 4.33) and high (⁸⁷Sr/⁸⁶Sr)_i (0.7085–0.7092) in dioritic intrusions indicate that these magmas are likely experienced assimilation of upper crustal materials. The interpretations of magmatic activity in the MBPC is consistent with the role considered for mantle-derived magma as heat and mass supplier for initiation and evolution of magmatism in continental arc setting, elsewhere.     

On dynamic coupling effects between a spar and its mooring lines

The responses of a spar constrained by slack mooring lines to steep ocean waves and tensions in the mooring lines are simulated using two different numerical schemes: a quasi-static approach (SMACOS) and a coupled dynamic approach (COUPLE). The two approaches are the same in computing wave loads on the structure. Their difference is in modeling dynamic forces of mooring lines; that is the dynamic forces are included in the computation of COUPLE but neglected in SMACOS. The numerical simulation is examined against the laboratory measurements of the JIP Spar in a water depth of 318 m. The dynamic coupling effects between the JIP Spar and its mooring lines in different water depths (318, 618 and 1018 m) are investigated by the comparison of numerical simulations obtained using the quasi-static and coupled dynamic approaches. It is found that the damping of mooring lines reduces the slow-drift surge and pitch of the Spar, especially in deep water. The reduction in the amplitude of slow-drift surge can reach about 10% in a water depth of 1018 m. The tension in mooring lines may greatly increase in the wave frequency range when dynamic forces in mooring lines are considered. The mooring-line tension in the wave frequency range predicted by the coupled dynamic approach can be eight times as great as the corresponding prediction by the quasi-static approach in a water depth of 1018 m. This finding may have important implications for the estimation of the fatigue strength and life span of the mooring lines deployed in deep water oceans.     

大洋铁锰结壳的地球化学与古海洋环境示踪

主要回顾近年来铁锰结壳在深度定年、主量元素、微量元素及Sr，Nd，Pb同位素地球化学及其古海洋环境示踪方面的主要研究进展，并提出有关认识和展望。