Iron and phosphorus effects on the growth of Cryptomonas sp. (Cryptophyceae) and their availability in sediments from the Pearl River Estuary, China

Based on lab-culture experiments analyzing limitation and combination of iron and phosphorus on the growth of Cryptomonas sp. (Cryptophyceae), and the study of accumulation and release of Fe-bound P in sediment cores collected from the marine region of the Pearl River Estuary, China, reasons for the high frequency of phytoplankton bloom therein are discussed. Results show that the combined effect of Fe and P can obviously accelerate algal development, and the optimum culture conditions maintaining maximum growth rate are 0.05 μM Fe and 50 μM P. Cellular contents of Fe and P is consistent and the P:Fe molar ratio is 159:1. The optimum range of the P:Fe molar ratio in culture experiments for cell incubation is 500–1400. The vertical trends of total Fe and total P variations in sediments are parallel. Fe-bound P is the main species of inorganic sedimentary P. Through continuous leaching with agitation, 34–80% of exchangeable P and 4–23% of exchangeable Fe are concurrently released from the surficial sediments. This is a possible way by which nutrients are made available to phytoplankton. These factors might be responsible for a high frequency of harmful algal blooms in the Pearl River Estuary.     

Late Quaternary palaeosols in the Yangtze Delta, China, and their palaeoenvironmental implications

The stiff clays beneath Holocene strata in the Yangtze Delta are interpreted as palaeosols, based on pedogenic features including illuvial argillans, voids, cracks, iron–manganese concretions and nodules, and carbonate materials. Variations in clay content with depth, the occurrence of foraminifera, and the environmental magnetism characteristics of the palaeosols suggest that their parent materials are floodplain deposits. Anisotropy of magnetic susceptibility (AMS) parameters of the sediments correlate well both with sedimentary dynamics and depositional processes in different sedimentary environments, and AMS analysis may be a useful tool for inferring sedimentary environments. Based on their considerable thickness (> 3.0 m), vertical changes of palaeosol maturity, and occurrence of ageing argillans throughout the palaeosols, the palaeosols are inferred to be compound ones (pedocomplexes) resulting from alternating deposition and pedogenesis on the palaeointerfluve of the Yangtze River. Phytoliths in the palaeosols indicate that climates turned generally from warm and wet to cold and dry with marked fluctuations during development of the palaeosols. This suggests that the palaeosols developed mainly during the marine regression prior to the last glacial maximum. The vertical distribution of manganese materials (e.g., concretions, nodules, speckles and mottles) in the palaeosols suggests that the groundwater tables were about 2.0–3.0 m beneath the upper boundary of the palaeosols during their development. Yellow–brown streaks and speckles are abundant from the middle to lower parts of the palaeosols, and layers with high CaCO₃ content occur in the strata just beneath the palaeosols, but which lack caliche, suggesting that the groundwater table fluctuated markedly during their development. Voids and cracks filled with clays, and carbonate nodules (less than 0.1 mm in diameter) with thin iron–manganese rims are abundant in the palaeosols, indicating that wet and dry seasons were marked during the palaeosol development. It is suggested that the monsoonal influence was marked in the Yangtze Delta, with both winter and summer monsoons strongly developed during the development of the late Quaternary palaeosols.     

A study of the factors influencing the occurrence of landslides in the Wushan area

Due to the complex natural geological conditions, many slope-related geological hazards occur in the Three Gorges Reservoir area in China. This study focuses on the characteristics of landslide development and their underlying mechanisms in this area. A statistical analysis is conducted to determine the characteristics of landslide development in the Wushan area, including the landslide distribution as a function of the elevation, slope, landslide material composition, scale, lithology, boundary conditions, instability mechanism, stratigraphic age, attitude, and sliding direction. The mechanisms of slope instability and the effect on the occurrence of landslides are analyzed. This study provides important reference material for landslide research in the Three Gorges Reservoir area and similar stratigraphic areas.     

河北大庙铁矿床黑云母40Ar/39Ar年龄及其地质意义

文章以野外观察为基础确定了致矿侵入体,以岩相学特征确立了测年样品的代表性。在此基础上,选取大庙铁矿大乌素沟矿区浸染状铁矿石中的黑云母进行了40Ar/39Ar年龄测定,坪年龄为(395.8±3.7) Ma,反等时线年龄为(395.6±4.0) Ma(2σ; MSWD=0.9; n=8)。因此,大庙铁矿及其致矿苏长岩的形成年龄约为396 Ma,相当于中泥盆世,而不是前人所认为的元古宙。新的测年结果与区域上近年来陆续识别出来的泥盆纪侵入岩类形成年龄一致,不仅表明华北克拉通的改造过程至少从泥盆纪就已经开始,而且暗示华北克拉通北缘仍有寻找其他“大庙式铁矿”的潜力。同时,文章提出,用成岩年龄作为成矿年龄时,需要有可靠的地质学和岩相学证据。 关键词：大庙式铁矿;斜长岩;苏长岩;40Ar/39Ar定年;成矿年代;华北克拉通     

山东黄河防洪工程建设占地问题探讨

0引言黄河流经山东省菏泽、济宁、泰安、聊城、德州、济南、淄博、滨州、东营9市,25个县(市、区),河道长628?。由于黄河含沙量高,大量泥沙淤积在河道内,造成目前河床高于两岸背河地面4~6m,设计洪水位高出背河地面8~10m,济南河段的2000年设计防洪水位高出济南市工人新村地面达11.6m,形成举世瞩目的地上悬河,防洪形势十分严峻。1998年“三江”大水之后,党中央、国务院对水利工作做出了一系列重大决策,加大了对大江大河的治理投资力度,加快了黄河下游的治理步伐。经过连续6年的建设,黄河山东段防洪工程整体强度得到明显提高,为战胜可能发生的大…     

斜方蓝辉铜矿在我国的发现及其微结构

作者在我国福建省上杭紫金山铜矿中发现了一种具有页片构造的Ｃｕ－Ｓ矿物。其基质相的化学式可表示为Ｃｕ１．７５６Ｓ,与１９６９年在日本发现的斜方蓝辉铜矿的化学式一致,这是该矿物在我国的首次发现;该矿物页片相的化学式可表示为Ｃｕ１．６８４Ｓ,是笔者未曾描述过的一种新的Ｃｕ－Ｓ矿物相,该矿物基质相和页片相混合的Ｘ射线衍射图谱上的绝大多数峰与合成斜方蓝辉铜矿的衍射峰可对应。由此,笔者认为上述成分略有差异的连     

鲁西石炭纪事件沉积岩石学特征

对鲁西地区石炭二叠纪煤系火山碎屑岩特征进行了分析,结果表明,火山碎屑物质以晶屑最为常见,常见的火山碎屑岩有凝灰岩、沉凝灰岩、凝灰质灰岩、凝灰质砂岩、凝灰质粉砂岩。还对在太原组煤层中发现的宇宙尘形貌及化学组成进行了研究,经与国内外相关资料对比,认为研究区宇宙尘为Si质玻璃球。提出了研究区石炭纪曾发生过火山地质事件、天体地质事件。      

煤田三维地震勘探中横向覆盖次数的确定及宽方位数据采集的设想

提出了线束型三维观测系统横向覆盖次数的一种简易确定方法,详细论述了非纵误差的实质及纵测线方向的选择方法,根据目前煤田三维数据采集现状,提出了宽方位角的设想,以便克服以往三维观测系统中方位角分布不均的弊端。      

山东昌乐凹陷油页岩地球化学特征及成因探讨

山东昌乐凹陷油页岩出产于古近系五图群李家崖组,与济阳拗陷和潍北凹陷孔二段相当。利用有机地球化学方法对昌乐凹陷油页岩品质进行分析,结果显示该区油页岩有机质丰度较高、干酪根类型主要为Ⅰ型和Ⅱ₁型,处于未熟低熟阶段,具有较好的勘探开发前景。通过区域构造演化和气候变化分析,昌乐凹陷油页岩形成于郯庐断裂带左旋右旋转换期,构造活动强度较弱加之温暖湿润的气候环境促成了油页岩的发育。油页岩与煤共生于水进体系域和高水位体系域之中,油页岩成矿模式为断陷湖沼型。