Long-term changes in the type,but not amount,of ingested plastic particles in short-tailed shearwaters in the southeastern Bering Sea

We report the current (1997-1999, 2001) incidence and amount of ingested plastic in short-tailed shearwaters (Puffinus tenuirostris) in the southeastern Bering Sea and compare our results with plastic reported in shearwaters during 1970-1978. We also examine correlations between plastic loads and shearwater body mass. We found that 84% (N = 330) of shearwaters sampled in 1997-1999 and 2001 contained plastic. The incidence and amount of ingested plastic have not significantly changed since the 1970s. In contrast, the predominant type of plastic has changed over time, from industrial plastic to user plastic. S,asonal patterns in the incidence and amount of ingested plastic also changed from peak levels during early and late summer in the 1970s to mid summer in the late 1990s and 2001. We suggest that the availability of neuston plastic to seabirds in the Bering Sea has undergone a shift in composition since the 1970s. Shearwater body mass appears little if at all impaired by plastic, at least at present levels of consumption.     

Analyses of organic and inorganic contaminants in Salton Sea fish

Chemical contamination of fish from the Salton Sea, a quasi-marine lake in Southern California, could adversely impact millions of birds using the Pacific Flyway and thousands of humans using the lake for recreation. Bairdiella icistia (bairdiella), Cynoscion xanthulus (orangemouth corvina), and Oreochromis spp. (tilapia) were sampled from two river mouths and two nearshore areas of the Salton Sea. Muscle tissues were analyzed for a complete suite of 14 trace metals and 53 pesticides. Fish muscle tissues had concentrations of selenium ranging between 1.89 and 2.73 microg/g wet weight. 4,4'-DDE accounted for 94% of the total DDT metabolites. Total DDTs ranged between 17.1 and 239.0 and total PCBs between 2.5 and 18.6 ng/g wet weight. PCB congeners 132, 138, 153, 168, and 180 comprised over 50% of the total PCBs. Given the potential implementation of a commercial fishing at the Salton Sea in the future, the presence of persistent organic pollutants and selenium warrants further research into the effects of these mixtures on fish populations, and on wildlife and humans consuming fish.     

楚科奇海的水螅水母类及其分布

本文报道 1 999年 7月至 8月我国首次北极科学考察期间“雪龙”号破冰船在楚科奇海采集的浮游水螅水母类及其分布。分析鉴定了 8种水螅水母 ,其中 4种属于花水母目 ,2种属于软水母目 ,1种属于硬水母目 ,1种属于筐水母目。短新塔水母在楚科奇海是首次记录。简要记述了这些种类的形态特征并附图。楚科奇海这 8种水螅水母都是冷水种 ,其中 6种为近岸性的 ,2种是大洋性的。根据其地理分布可分为北极种、北极 -北方种和北方寒温带种等 3个类型 ,从动物地理观点看 ,楚科奇海的水螅水母类应属于北极区系。楚科奇海水螅水母类的丰度一般较低 ,其平均丰度为 1 0 8个 /1 0 0 m3,水平分布状况主要由优势种所左右 ,八斑腕唇水母和指腺华丽水母为优势种。垂直分层采样结果表明 ,指腺华丽水母分布于 0～ 30 0 m,其中以 50～ 1 0 0 m居多     

南海诸岛外来地名的命名背景及其历史影响

19世纪中叶至20世纪30年代英美等国在我国南海海域的测绘活动,给这里的岛礁留下了一大批以英语为主的外语名称。文中论述了南海诸岛外来地名的命名背景及其对我国三次公布官方名称所产生的深刻影响,在总结历史教训的基础上,分析了当前处理南海地名问题的缺陷,提出了若干改进建议。     

PRELIMINARY ANALYSES OF THE ACTIVITIES OF SOUTH CHINA SEA SUMMER MONSOON IN 1998

The NCEP reanalyzed data, OLR and SST observations are used to study the onset time and the multi-time scales features of the South China Sea (SCS) summer monsoon in 1998 and its interaction with the sea surface temperature and the effect on the precipitation in Guangdong province. It is found that the 1998 SCS summer monsoon set in on May 17 (in the fourth pentad of the month). The year witnesses a weak monsoon with the OLR oscillating at cycles of about 1 month and the Southwest Monsoon of about 1/2 month. The mon-soon over the Bay of Bengal and the cross-equatorial current near 105°are two driving forces for low-frequency variations of the SCS monsoon. The weak activity in the year was resulted from positive anomalies of SST in the equatorial eastern Pacific in early spring and subsequent formation of positive anomalies of SST in the SCS through the Arabian Sea.     

Topex/Poseidon Altimetry and Dynamics of the Ocean-Atmosphere System

The T/P altimeter data 1993 – 1997 (cycles 11 – 194) has been analyzed with emphases on seasonal variations in sea surface topography (SST). The amplitude of the annual variations amounted to (5.9±0.3) mm when inverted barometer (IB) corrections were applied and (2.0±0.4) mm without any IB corrections. The amplitude of the semi-annual variations in SST was small with IB corrections applied: (0.6±0.3) mm. However, when no IB corrections were applied, it was (1.8±0.4) mm, i.e. the semiannual variations are at the same level as the annual variations with no IB corrections. The phase angle offset of the annual term has shifted by about 180° when IB correction was applied. The dynamics of the ocean-atmosphere system is discussed and it is concluded that it could, at least partly, be responsible for the above observed effects.     

南海西北部珊瑚礁记录所反映的新构造运动*

珊瑚礁是发育于热带海洋环境中由生物作用和地质作用共同形成的地质体,具有独特的新构造运动意义。南海西北部珊瑚礁记录所反映的新构造运动主要有火山活动、地壳升降运动和地震活动等。珊瑚礁区第四纪火山活跃,到现代已停止活动,部分火山构成珊瑚礁的基座,个别出露海面为火山岛;地壳升降运动差异较大,雷州半岛西南部珊瑚礁呈上升趋势,上升率为0.02~0.05mm/a;西沙群岛等岛礁地壳运动则呈下降趋势,下降率为-0.07~-0.10mm/a,岛礁中的造礁石珊瑚生长率、礁顶和灰沙岛的堆积率均相当于或大于地壳下降率与现代海平面上升率的总和;南海西北部珊瑚礁区内地震活动较强,尤其是1994年12月31日和1995年1月10日在雷州半岛西南部海域发生了6.1级和6.2 级地震,这两次地震对该区珊瑚礁的发育有较大的影响。     

东海天然气水合物地热研究及其环境意义

依据地热资料研究天然气水合物稳定带厚度在东海海域的分布情况。东海在地质构造上位于新生代环太平洋构造带西部边缘岛弧的内侧,又是欧亚板块、太平洋板块和菲律宾海板块的相互作用带。依据国际热流委员会(IHFC)提供的东海地热数据,经过统计确定出该区域的热流分布,热流平均值为121·0mW/m2,最小值为73·0mW/m2,最大值为168·0mW/m2。同时利用天然气水合物温压模型计算了稳定带厚度,数据显示稳定带厚度平均值为92·2m,最小值为1·4m,最大值为190·6m,薄于其他已经发现的海洋天然气水合物稳定带厚度(约400m)。天然气水合物大部分分布在条件适宜的陆坡和岛坡上,冲绳海槽底部水合物稳定带厚度相对较薄。统计分析表明本区热流值与水合物稳定带厚度相关性很差,相关系数仅有0·12。这是由于天然气水合物所在海域水深较浅时,海底温度的变化迫使运算所应用的非线性方程影响因子迅速积累,从而导致相关系数降低。最后结合东海陆坡的地质条件,探讨了在天然气水合物存在的情况下,陆坡失稳的可能性及其造成的环境影响。     

Mantle process beneath Philippine Sea back-arc spreading ridges: A synthesis of peridotite petrology and tectonics

Abstract In order to obtain a general view of the mantle process beneath a back‐arc basin spreading ridge, the diversity of peridotite petrology and tectonic occurrences in two back‐arc basin spreading ridges from the Philippine Sea were examined: the Parece Vela Rift and the Mariana Trough. The Parece Vela Basin spreading ridge (Parece Vela Rift) was a physically fast/intermediate‐spreading ridge, although many tectono‐magmatic features resemble those of slow‐ to ultraslow‐spreading ridges. Two unusual features of the Parece Vela Rift further demonstrate the uniqueness of the ridge: full‐axial development of oceanic core complexes and exposure of mantle peridotite at segment midpoints. The Parece Vela Rift yields a lithological assemblage of residual but still fertile lherzolite/harzburgite, plagioclase‐bearing harzburgite and dunite; similar assemblages are reported from the equatorial Mid‐Atlantic Ridge at the Romanche Fracture Zone and the ultraslow‐spreading ridges from the Indian and Arctic Oceans. The tectono‐magmatic characteristics of the Parece Vela Rift suggest that diffuse porous melt flow and pervasive melt–mantle interaction were the important mantle processes there. Globally, this ‘porous melt flow‐type’ mantle process is likely to occur beneath a segment midpoint of the ridge having a thick lithosphere, typically an ultraslow‐spreading ridge. In contrast, the Mariana Trough is a typical slow‐spreading ridge, exposing mantle peridotite at segment ends. The Mariana Trough yields a lithological assemblage of residual harzburgite and veined harzburgite, a common assemblage among the global abyssal peridotite suite. The tectono‐magmatic characteristics of the Mariana Trough suggest that channeled melt/fluid flow and limited melt–mantle interaction are the important mantle processes there, because of the colder wall‐rock peridotite in the segment end. This ‘channeled melt flow‐type’ mantle process is likely to occur in the shallow lithospheric mantle at the segment ends of any spreading ridges.     

Organic facies and geochemical aspects in Neogene neritic sediments of the Takafu syncline area of central Japan: Paleoenvironmental and sedimentological reconstructions

Abstract Organic petrological observations of kerogen macerals and organic geochemical analyses of carbon isotopes of kerogen macerals and biomarkers were conducted on Neogene neritic sediments of the Takafu syncline area of central Japan. The Senmi, Sakainomiya and Lower Shigarami Formations in that area were deposited at the neritic provinces on the southern edge of the paleo‐Japan Sea during the Late Miocene to Early Pliocene. Sedimentary organic matter in these formations was almost terrigenous in origin. Changes in kerogen maceral compositions reflect sedimentological and tectonic histories evaluated in previous studies from sedimentary facies and paleontology. It was found that carbon isotope ratios (δ¹³C) of kerogen macerals increased from ?28‰ to ?25‰ from the Sakainomiya to the lower part of the Lower Shigarami Formations. The cause of that increase was presumably the expansion of C₄ plants into southwest Japan. The timing was concordant with that of the expansion of C₄ plant grasslands in East Asia. The oxicity (oxic to anoxic) conditions of sea bottoms evaluated from pristane/phytane ratios varied. Particularly, in the lower part of the Senmi Formation, layers in which no steroid biomarkers could be detected were found, and had presumably formed under oxic conditions when strong biodegradation had occurred. Concentrations of regular (C₂₇–C₂₉) steranes and dinosteranes were higher in the Sakainomiya and Lower Shigarami Formations. This indicates that dinoflagellates‐dominant primary productions were higher at those stages. In addition, concentrations of diatomaceous biomarkers such as C₂₆ norsterane increased from the Lower Shigarami Formation, thus adding diatoms to the major producers. Furthermore, similar associations between the increases of δ¹³C values of kerogen macerals and concentrations of diatomaceous biomarkers were observed in the Takafu syncline area. Thus, the expansion of C₄ plants was possibly associated with the high production of diatom in the shallow‐marine areas of the paleo‐Japan Sea during the Neogene Period.