季节性水域卵石地基桥梁基础圆形组合围堰应用技术研究

本文以重庆轨道交通18号线李家沱长江复线桥为工程背景,李家沱长江复线桥南岸辅墩P4、P5基础常年位于长江水域中,水深0~17.5 m随季节变化,河床覆盖层为9.2~11.2 m厚卵石土,下伏基岩为砂质泥岩及砂岩互层;根据水文地质情况,通过围堰方案比选,李家沱长江复线桥南岸辅墩P4、P5基础施工采用圆形组合围堰,在水下卵石土基础部分采用混凝土咬合桩围堰,解决了卵石土状况下双壁钢围堰的下放和稳定难题;在咬合桩围堰顶部设置冠梁,通过冠梁预埋钢构件把混凝土咬合桩围堰(下节)和双壁钢围堰(上节)牢固连接,利用上下节围堰来解决不同季节水位变化下桥梁基础施工问题。根据围堰设计进行结构分析,圆形组合围堰具有较好的过流程能力及抵抗水压能力,并经现场施工实施效果良好,围堰经过长江百年一遇洪水后结构稳固、无变形,为季节性水域卵石地基桥梁基础施工提供参考与借鉴。

Seasonal Gametogenesis of Host Sea Anemone(Entacmaea quadricolor) Inhabiting Hong Kong Waters

Studying gonadal development of annual cycle can reveal the process of gametogenesis and reproductive period, and evaluate fertility and source utilization of a species. Host sea anemones are conspicuous members of tropical and subtropical reef ecosystems, but little is known about its biology including reproductive seasonality. Here we reported a one-year study on the gametogenesis and reproduction of host sea anemone(Entacmaea quadricolor) inhabiting Hong Kong waters. E. quadricolor tissues were sampled in 12 occasions from 5 m and 15 m depths of water, respectively. Histological sectioning of the tissues showed that E. quadricolor was dioecious, and populational ratio of female to male was 1:1.6. The gonadal development was asynchronous within an annual cycle, which included proliferating, growing, maturing, spawning, and resting stages. The spawning occurred between August and October when surface seawater temperature reached the annual maximum(28℃), suggesting that temperature is an important factor modulating the gonadal development and mature of E. quadricolor.

Seasonal Variation of Cochlodinium polykrikoides in the North of Oman Sea （Iranian Waters）

This study was carried out to investigate the Cochlodinium polykrikoides fluctuations in the north of Oman Sea during pre- and post-monsoon season in 2008. The study area was divided into 10 transects （TI-T10） from the Strait of Hormuz （T1） to Gwadar （TI0） which cover the whole of the Iranian waters in the Oman Sea. The results showed that at first, Cochlodinium polykrikoides appeared in the northeast part （T10） in the pre-monsoon season, then it spread to other parts of the study area. Cochlodinium polykrikoides was observed in greater abundance in the Strait of Hormuz in the post-monsoon season. The results demonstrated that T10 （transect 10） had the highest abundance in the pre-monsoon season. The Kruskal-Wallis test showed a significant difference among transects （P 〈 0.05）. The present study showed that the abundance of Cochlodinium polykrikoides increased from coastal to offshore waters in the pre-monsoon season; however, in the post-monsoon season, there was a higher abundance in coastal waters compared to the offshore zone. It could be seen that the abundance of Cochlodinium polykrikoides started in offshore waters, then increased in coastal waters. During the pre-monsoon season, water discoloration was not observed, however, the water changed to brown from T 1 to T4 （northwest） and blooms of Cochlodinium polykrikoides was recorded in the post-monsoon season.

Assessing the Seasonal Predictability of Summer Precipitation over the Huaihe River Basin with Multiple APCC Models

Seasonal rainfall predictability over the Huaihe River basin is evaluated in this paper on the basis of 23-year(1981-2003) retrospective forecasts by 10 climate models from the Asia-Pacific Economic Cooperation(APEC) Climate Center(APCC) multi-model ensemble(MME) prediction system.It is found that the summer rainfall variance in this basin is largely internal,which leads to lower rainfall predictability for most individual climate models.By dividing the 10 models into three categories according to their sea surface temperature(SST) boundary conditions including observed,predicted,and persistent SSTs,the MME deterministic predictive skill of summer rainfall over Huaihe River basin is investigated.It is shown that the MME is effective for increasing the current seasonal forecast skill.Further analysis shows that the MME averaged over predicted SST models has the highest rainfall prediction skill,which is closely related to model's capability in reproducing the observed dominant modes of the summer rainfall anomalies in Huaihe River basin.This result can be further ascribed to the fact that the predicted SST MME is the most effective model ensemble for capturing the relationship between the summer rainfall anomalies over Huaihe River basin and the SST anomalies(SSTAs) in equatorial oceans.

Morphotaxonomy and seasonal distribution of planktonic and benthic Prorocentrales in Karachi waters,Pakistan Northern Arabian Sea

Morphotaxonomy and seasonal abundance of dinoflagellates of the genera Prorocentrum and Mesoporos （Prorocentrales） were studied from nutrient-rich waters, Karachi Harbor and the mouth of the Manora Channel, Pakistan during May 2002-July 2003. Using both light and scanning electron microscopy, 13 species of Prorocentrales were identified according to cell shape, size, ornamentation of thecal plates, and architecture of apical platelets, apical pore area, marginal pores, and intercalary bands. P. sigmoides, P. arcuatum, P. scutellum, P. donghaiense, P. balticum, P. minimum, P. emarginatum, P. lima, P. faustiae, and Mesoporos perforatus constitute new records for sindh coast of Pakistan. The most abundant species were P. minimum/P, balticum （4.5x103 cells/L）, P. micans （1.1~103 cells/L）, P. gracile/P, sigmoides （2.5 x 102 cells/L） and P. donghaiense （6.6 x 103 cells/L） at temperatures of 29-31 ~C and salinities of 35-40. Maximum abundance was observed in winter and lower abundance in summer. There was no significant change in the distribution of species between stations except for the benthic species which occurred close to Karachi Harbor waters. Significant positive correlations were observed between Prorocentrum spp. and temperature （R2=0.27） and negative correlations with salinity （R2=-0.32） except for P. minimum and P. emarginatum which has negative correlation with temperature （R2=-0.24） and positive with salinity （R2=0.08, 0.19）. The finding of potential okadaic-acid producing species of benthic Prorocentrum call for monitoring for possible human health problems in this region.