The Combined Effect of Plastic Particles Size and Concentration on Rotifers’ (Brachionus plicatilis) Performance

The presence of microplastics in aquatic ecosystems is of increasing global concern.Nano-sized plastics,in particular,can penetrate the cell membrane and cause biological death.Our study evaluated the combined impacts of several polystyrene mi-crospheres’sizes and nominal concentrations on the overall performance changes of Brachionus plicatilis.Experimental animals were exposed to three microplastic sizes(0.08,0.5 and 6μm)and five nominal concentrations(0,0.5,2,8,32μg mL?1)for 20 d.Our results showed that the toxicological effect of particle size on rotifers did not significantly depend on the nominal concentration.The interaction between the nominal concentration and size occurred only for body length and lorica width.Specifically,high nominal concentrations of microplastics that were close to nanometer size significantly impaired the overall vitality of rotifers,embodied in shortage of body type,delay in the arrival of maturity,reduction in the cumulative number of neonates,and the advance of the death process.In comparison,fair-sized size(0.5 and 6μm)displayed non-significant damage except for individual groups.Most notably,the net reproductive yield was only a third of what it was in the original environment,implying that there was not much fertility left.Besides,with the development of rotifers,the adverse effects of polystyrene microsphere drive had become more and more serious.     

区域铜元素的空间变异和自相关规律分析

研究地球化学元素在地球化学场中的空间最大变异距离、空间聚集以及空间异常分布情况。通过稳健半变差函数确定空间最大变异距离,在最大变异距离内分别对在不同的距离、原始数据和经过Box-Cox变换的数据使用局部空间自相关Moran′s Ii指数研究元素含量的空间聚集和空间异常,与基于C-A多重分形法的异常下限确定方法所圈定的异常范围进行对比。以面积为8 130km2的铜矿区所采集的1∶20万水系沉积物1 341个组合样点的Cu元素含量为例,局部Moran′s Ii能很好地划分空间聚集和空间异常,尤其是针对经过变换的数据能探测出比C-A法范围更大的聚集和异常,符合客观实际,与已知矿床(点)吻合很好。     

K-Ar Dating of Fault Gouges from the Red River Fault Zone of Vietnam

Constraining the timing of fault zone formation is fundamentally important in terms of geotectonics to understand structural evolution and brittle fault processes.This paper presents the first authigenic illite K-Ar age data from fault gouge samples collected from the Red River Shear Zone at Lao Cai province,Vietnam.The fault gouge samples were separated into three grain-size fractions(0.1 μm,0.1-0.4 μm and 0.4-1.0 μm).The results show that the K-Ar age values decrease from coarser to finer grain fractions(24.1 to 19.2 Ma),suggesting enrichment in finer fraction of morerecently grown authigenic illites.The timing of the fault movement are the lower intercept ages at 0%detrital illite(19.2 ± 0.92 Ma and 19.4 ± 0.49 Ma).In combination with previous geochronological data,this result indicates that the metamorphism of the Day Nui Con Voi(DNCV) metamorphic complex took place before ca.26.8 Ma.At about 26.8 Ma-25 Ma,the fault strongly acted to cause the rapid exhumation of the rocks along the Red River-Ailoa Shan Fault Zone(RR-ASFZ).During brittle deformation,the DNCV slowly uplifted,implying weak movement of the fault.This brittle deformation might have lasted for ca.5 Ma.     

A three-phase model for evaluating the seismic resistance of soils reinforced by a network of symmetrically inclined piles

The stability analysis of a piled embankment under seismic loading is considered, with a special emphasis on the optimization of the reinforcement layout by splitting the initial group of vertical piles into two symmetrically inclined arrays of parallel inclusions. The bidirectionally-reinforced soil thus obtained is appropriately described, at the macroscopic scale, by a three-phase model, conceived as an extension of the two-phase model previously developed for unidirectionally-reinforced soils. The model is implemented in a finite element formulation and related numerical code, which is used for simulating the behavior of the piled embankment up to failure. The results of these simulations, which favourably compare with upper bound yield design calculations, clearly indicate that the seismic resistance of the embankment can be considerably increased from symmetrically inclining the piles, even without taking the potential benefits of their flexural resistance into account.     

越南西北部Pu Sam Cap高钾碱性岩LA-ICPMS锆石U-Pb年龄与Hf同位素组成及其区域构造意义

越南西北部Pu Sam Cap高钾碱性杂岩位于哀牢山剪切带南段西侧,由粗面岩、煌斑岩、碱性正长岩与碱性花岗岩组成。其中粗面岩不整合于晚白垩世陆相沉积岩之上,碱性侵入岩侵入到三叠纪陆源沉积岩、侏罗纪流纹岩及40～35Ma含角闪石二长岩-花岗岩中。该杂岩的岩石具有低TiO2(0.8%)、P2O5(0.64%)和FeO*(7.74%),高Na2O(1.41%～4.5%)和K2O(5.22%～9.4%)的地球化学属性,属于高钾碱性玄武质到高钾碱性长英质岩浆岩类型与钾质至超钾质岩浆系列。这套岩石富集大离子亲石元素LILE、轻稀土元素LREE和一组相容元素,具有明显的Ta、Nb和Ti异常,表明Pu Sam Cap高钾碱性杂岩形成于与俯冲带有关的大陆弧和后碰撞弧构造环境。锆石LA-ICPMS U-Pb年代学研究表明碱性正长岩与碱性花岗岩分别形成于32.70±0.24Ma、35.1±0.06Ma,上述年龄代表了Pu Sam Cap高钾碱性杂岩的侵入岩结晶年龄。两个样品中锆石的εHf(t)变化范围分别为-2.8～2.5和-4.9～0.1,在t-εHf(t)相关图上分析点落在下地壳和亏损地幔演化线之间,两阶段模式年龄变化范围为950～1286Ma和1107～1421Ma。该杂岩的εNd(t)变化范围-5.63～-3.26,具有低143Nd/144Nd比值(0.512336～0.512447)和高87Sr/86Sr比值(0.706254～0.707273),Sr-Nd同位素相关图上接近于EM2地幔端元趋势线,与大理地区新生代高钾岩浆岩十分相似,表明PuSamCap高钾碱性杂岩的岩浆是幔源岩浆和壳源岩浆的混合结果,同时可与大理地区新生代高钾岩浆岩对比,它们形成于哀牢山-红河左行走滑活动之前,墨江古特提斯洋盆的消减与印度-欧亚陆陆碰撞活动提供了宏观区域性构造背景。