Heinrich layer in Antarctic marine sediments and its significance to global changes

Results of grain size analysis and rock magnetic measurements of core NP95-1 from Prydz Bay, Antarctica revealed two series of ice-rafted detritus layers, which correspond to cold climatic events, Younger Dryas and Heinrich event 1, occurring at about 11.7-10.3 and 14.3-13.6 kaB.P. respectively. Studies also show that the sequence of paleoclimatic changes in Antarctica can be correlated with that in other parts of the world, and that the millennia1 climate of the earth could change synchronously and globally. In addition, magnetic fabric analysis also shows a close relationship between paleoclimatic change and ocean circulation re-assemblage.     

红树杆物落叶碎屑对水中重金属吸附的初步研究

研究四种红树植物落叶碎屑对水环境中重金属Ｃｕ、Ｐｂ、Ｎｉ和Ｃｄ离子的吸附作用．结果表明：１）在单离子处理条件下,白骨壤叶对Ｐｂ、Ｃｄ的吸附能力较强;而秋茄叶对Ｃｕ、Ｎｉ的吸附能力较强．２）在相同离子浓度下,拒盐植物（秋茄、红海榄）与泌盐植物（白骨壤、桐花树）落叶碎屑对不同重金属吸附能力具有一定差异：拒盐植物为Ｃｄ＞Ｐｂ＞Ｃｕ＞Ｎｉ;而泌盐植物为Ｐｂ＞Ｃｄ＞Ｃｕ＞Ｎｉ．３）随着水中重金属浓度增加（２～５ｍｇ／Ｌ）落叶碎屑对重金属吸附量随之增大,表明红树落叶碎屑对重金属的吸附具有较大的潜在容量．４）多种重金属离子共存下,四种植物落叶对不同离子的吸附量均表现为Ｐｂ＞Ｃｄ＞Ｃｕ＞Ｎｉ     

Seasonal reproduction in deep-sea Crustacea (Isopoda: Asellota)

A collection of Crustacea Isopoda (suborder Asellota) from a 10-year sampling programme in the Rockall Trough, NE Atlantic (54°40′N, 12°15′W) was analysed for evidence of breeding seasonality. No evidence of seasonal activity was found — adults and newly released juveniles were present throughout the year — but there was a strong seasonal pattern for breeding intensity. A significantly higher proportion of females was brooding during the winter months (25%) compared to the summer (5%), and the percentage of females brooding varied significantly with depth. The breeding pattern was synchronized to the seasonal deposition of organic detritus known to occur during the summer in the NE Atlantic. There were more newly released juveniles in samples during the summer than during the winter, with most females appearing to release their young at the time the deposition began. This deposition appears to be a major seasonal factor dominating the life-cycles of most benthic species in the Rockall Trough. Juvenile settlement for a range of taxa (echinoderms, molluscs and crustaceans) occurs while the detritus is present and most species maximize vitellogenesis at this time.     

朽木,煤核与成煤作用

吕合矿第三纪煤中含大量煤核、朽木和矿化木。煤核多分布在顶板下附近,在煤核内矿化部位各异,朽木和矿化木则分居在距顶板较远的煤内和煤层上部。根据它们分布规律和各自特点,朽木是这里形成大量煤核和矿化木的先决条件。各种真菌对不同造煤植物或对同一植物的不同部位进行选择性破坏形成不同的朽木,朽化处再不能参与凝胶化成煤而在一定条件下被矿化成形态各异的煤核或矿化木。矿化成煤核是煤层内大部分朽木的最终归宿,少量被解体为矿物和类惰屑体参与成煤作用。     

赤潮藻类生态营养模型非线性动力学研究

基于营养盐、赤潮藻类、碎屑的生物量之间的食物链关系,考虑到由于海洋内微生物分解动植物遗体对营养盐的补充以及物理因素导致的流失,建立了营养盐-赤潮藻类-碎屑的生物量相互作用的耦合生态动力学模型。运用现代非线性动力学理论,对模型解的动力学稳定性进行了分析。结果表明,随着参数的变化,系统稳定性也随之变化,甚至出现HOPF分岔现象。     

Intense inhabitation and relaxed host-leaf preference of aquatic chironomid leaf-miners in headwater streams in Asian lucidophyllous forests

Submerged leaf litter in headwater streams covered by Asian lucidophyllous (glossy broad-leaved evergreen) forests was found to be frequently processed by leaf-mining larvae of a chironomid, Stenochironomus okialbus. The larva gnaws plant tissue of the mine wall while swimming and undulating its body in the water-filled mine. To detect the level of the inhabitation and host-preference of the aquatic leaf-miner, extensive samplings of mined leaves were made in various headwater streams covered by lucidophyllous forests in the Japanese Island Arc. The chironomid showed significant preference for leaf texture (evergreen to deciduous leaves) and for specific taxonomic groups of the host plants (Fagaceae and Lauraceae), whereas diverse taxa of leaves were utilised. The relaxed host-leaf preference unique among herbivorous insects is suggested to be caused by the larval water-circulating behaviour in their porous mines and by leaching and microbial decomposition of plants’ secondary metabolites in submerged leaves.