Heavy metals and phosphorus in tidal flat sediments of the Yangtze estuary

Concentrations of heavy metals (Cu, Pb, Zn, Cr and Cd), and phosphorous (P) were determined in surface tidal flat sediments of the Yangtze estuary and Shanghai coast. Results demonstrate that there were significant differences among the accumulation of the heavy metals in sediments, following the order: Zn > Cu > Cr > Pb > Cd. The spatial distribution and chemical forms of heavy metals in tidal flat sediments were closely related to the distribution of pollution resources (outlet of sewage) and the local sedimentary and hydrodynamic conditions. The dominated form of non-residual heavy metals is bound to Fe/Mn oxides, and the next form is bound to carbonates. Moreover, contents of total P in sediments range from 18.0 μmol.g-1 to 31.4 μmol.g-1 along the coastline, speciation of P in sediments was different, most of P in tidal flat sediments is associated with calcium phases (as Ca-P) similar to marine sediments.     

重液变温分离单矿物在铷锶年代学中的应用

报道了应用重液变温分离法分离白云母、黑云母、透长石和石英等单矿物,进行铷锶等时线年龄测定的研究结果。这些结果表明,同一单矿物具有微小比重差的组分,其Rb、Sr同位素比值具有明显的线性展布,在铷锶年代学研究中具有良好的应用前景和潜力。     

The ecosystem of a mesotrophic lake-II. Interactions among nutrient load,river flow,and epilimnion depth

The management variables which primarily affect phytoplankton biomass (as chl-a) in Lake Mjøsa, Norway, are total phosphorus loading (TP) and the timing and volume of water through flow (by active storage reservoirs). The response of the lake to changes in these factors is studied using a simulation model of the lake ecosystem. Chl-a responses from both observed data and the simulated results are extracted by multiple regression. Results show that decreasing TP load decreases chl-a, but less at low TP levels (< 10 mg TP · m^–3). There is also a certain time period for peak river flow which gives the least yield of chl-a per unit TP. This time period occurs in early summer (i.e., around June 10) if the total phosphorus load is low, and later if the load is high. Both observations and simulation results show that a high water flow increases chl-a at low epilimnion depths (< 15 m), but that the same high water flow decreases chl-a when epilmnion is deep.     

矿物包裹体液相组分变化原因初析

本文介绍在不同条件下所测定的矿物包裹体成分变化及引起变化的原因。     

Measurement of total dissolved phosphorus in small volumes of iron rich interstitial water

It is shown that sorption of orthophosphate to iron compounds, formed during persulfate digestion, can cause a significant underestimation of total dissolved phosphorus in interstitial waters rich in iron and poor in phosphorus. Labelling the samples with carrier free³²PO₄ before digestion allows to correct for these losses.     

非饱和土微观结构与粒间吸力的研究进展

吸力是非饱和土研究的重点也是其难点。重点在于自然界中诸多物理现象可以用吸力去解释，难点在于非饱和土吸力的量化测试技术现在还不成熟。非饱和土作为地球表层广泛存在的三相组合材料，其力学性质远远比饱和土复杂，归根结底在于土中水气界面形成的弯液面收缩膜，导致了土体孔隙产生吸力。非饱和土体的强度变形特征就是其内部吸力不断变化的宏观表现形式，其宏观物理力学性质与吸力之间存在一个桥梁——微观结构。对非饱和土微观结构和吸力理论、试验研究的整体把握是完善土力学的一个重要方法。开展对非饱和土液桥动态结构演化及吸力力链分布特性的研究，是全面了解非饱和土力学性能的重要基础之一，也是深入把握和量化非饱和土吸力的重要手段。     

农业区非点源污染潜在危险性评价——以于桥水库流域磷流失为例

在农业非点源污染研究中,确定农业非点源污染的关键源区或危险区域是开展有针对性研究和控制农业非点源污染的首要问题之一.本文在地理信息系统的支持下,综合考虑了影响于桥水库流域农业非点源磷流失的源因子和迁移因子,通过建立评价指标体系,计算磷污染危险性指数,对农业非点源磷流失危险性进行定量化评价,识别具有极高危险性或较高危险性的区域为磷流失的关键源区,将其作为控制和管理的优先区域和重点区域.结果表明:流域中磷流失危险性极高和较高的区域即关键源区不到全流域面积的6.0%,危险性中等的地区占到整个流域面积的20.52%;具有高和中等危险性的地区主要分布在流域河流两岸,且具有极高或较高的土壤有效磷含量或化肥磷施用量或高的土壤侵蚀强度,大部分为流域中部丘陵平原区的农田,少部分为地形较陡的山区农田.     

射流式液动锤回转冲击孕镶金刚石钻头钻进的实践与分析

金刚石本身力学性质、金刚石钻头结构特点及射流式液动锤冲击力特点决定了射流式液动锤带金刚石钻头进行冲击回转钻进是可行的。经射流式液动锤在科学钻探主孔先导孔中的应用实践，证明了由于液动锤冲击动载作用钻头底唇面与岩面微量问隙有规律地变化，改善钻头金刚石颗粒受力状况、碎岩状态，提高钻头金刚石颗粒切入深度，改善胎体磨损状况、钻头冷却，成倍地提高了榴辉岩、片麻岩等坚硬地层中钻进回次进尺、机械钻速及钻头平均寿命。