Herbicides implicated as the cause of severe mangrove dieback in the Mackay region, NE Australia: consequences for marine plant habitats of the GBR World Heritage Area

Herbicides, particularly diuron, were correlated with severe and widespread dieback of the dominant mangrove, Avicennia marina (Forsk.) Vierh. var. eucalyptifolia (Val.) N.C. Duke (Avicenniaceae), its reduced canopy condition, and declines in seedling health within three neighbouring estuaries in the Mackay region of NE Australia. This unusual species-specific dieback, first observed in the early 1990s, had gotten notably worse by 2002 to affect >30 km(2) of mangroves in at least five adjacent estuaries in the region. Over the past century, agricultural production has responded well to the demands of increasing population with improvements in farm efficiency assisted by significant increases in the use of agricultural chemicals. However, with regular and episodic river flow events, these chemicals have sometimes found their way into estuarine and nearshore water and sediments where their effects on marine habitats have been largely unquantified. Investigations over the last three years in the Mackay region provide compelling evidence of diuron, and possibly other agricultural herbicides, as the most likely cause of the severe and widespread mangrove dieback. The likely consequences of such dieback included declines in coastal water quality with increased turbidity, nutrients and sediment deposition, as well as further dispersal of the toxic chemicals. The implications of such findings are immense since they describe not only the serious deterioration of protected and beneficial mangrove habitat but also the potential for significant direct and indirect effects on other highly-valued estuarine and marine habitats in the region, including seagrass beds and coral reefs of the Great Barrier Reef lagoon. This article reviews all key findings and observations to date and describes the essential correlative and causative evidence.     

The effects of sand extraction on the macrobenthos of a relict sands area (northern Adriatic Sea): results 12 months post-extraction

Sands for the nourishment of beaches along the Emilia-Romagna coast (northern Adriatic Sea) were dredged from an offshore area characterised by relict sands formed during the last Adriatic post-glacial transgression. The short-term effects of the sand extraction on macrozoobenthic communities were investigated before, during and 1, 6 and 12 months after dredging at three impacted stations and seven control stations. Sand extraction activities did not significantly influence the granulometry and %TOC in the sediment but caused almost complete defaunation at dredging stations. Yet, just 12 months after the extraction, the recolonisation of communities at the impacted stations was at an advanced stage. Unlike other studies on the effects of extraction of marine sand, no significant settlement of opportunistic species was observed. The limited impact of the sand extraction operation on the physical characteristics of the sediment and hydrological-sedimentary characteristics in the relict sand area should aid its rapid recovery and the restoration of the original community in a short period of time (2-4 years after dredging).     

工程物探中地震层析成像的研究

从实际情况出发，讨论工程中应用地震层析成像方法几个环节中的一些具体问题，包括资料采集中观测系统的装置，原始资料的分析和预处理，以及资料处理时如何选择合适的参数等。文中提出的扫描法、快速搜索法等弯曲射线校正方法克服了以往方法计算量大、存在盲区等缺点。反演实测资料效果良好。     

短圆柱体有效退磁系数的实验测定

对比球体和圆柱体的测量结果表明:一个轴比(axial ratio)(长度/直径)≈0.9,磁化率≈0.8(CGS)的短圆柱体,它在轴向和径向的有效退磁系数N≈3.7。因此,磁化率大的短圆柱体在三个互相垂直方向的有效退磁系数的和小于4π。在测定强磁性磁铁矿标本的磁性时,这点颇为重要。     

地壳反射和区域P型尾波的特征

本文给出了斯堪的纳维亚的ＮＯＲＥＳＳ、ＦＩＮＥＳＡ和ＡＲＣＥＳＳ台阵及新英格兰的ＮＹＮＥＸ台阵所记录地震的区域Ｐ型尾波的Ｆ－Ｋ谱，该谱由沿事件方位传播的具有Ｐｎ波（或更快波）和Ｌｇ波之间视速度的能量所控制。     

Tookoonooka, a large buried early Cretaceous impact structure in the Eromanga Basin of southwestern Queensland, Australia

Abstract— The ～66 km wide Tookoonooka impact structure (27°07′S, 142°50′E) was first recognised, from seismic profiles, as a circular structure consisting of a concentric arrangement of anticlines and synclines, which surround a complex central dome, ～22 km wide. A gravity low and a central magnetic high characterize the structure. Now buried by up to 900 m of Cretaceous and Tertiary clastic sediments, the Tookoonooka structure was formed ～128 Ma ago, during deposition of the paralic Cadna-owie Formation. Thin sections from a centrally located exploration well reveal an impact melt breccia, composed of local Ordovician quartz-mica schist bedrock. Detailed study of planar deformation features (PDFs) in quartz grains from this breccia show 64 lamellae sets in 25 grains. Most of the PDF measurements correspond to ζ {112～2} andr/z {101～1}/ {011～1} crystallographic indices, with five other orientations also measured. This distribution of PDFs corresponds to that found in quartz from impact structures in porous sedimentary rock targets, thus confirming an impact origin for Tookoonooka.     

Placing identity: interviews with Hong Kong Chinese immigrants in Britain and Canada

"This paper explores the ?borderline community of migration'.... The placing of migrant identities is examined in the context of Hong Kong immigrants in Britain and Canada. Changes in identity and the meaning of the multiplicity of migrant identities are explored through interview material. The tensions between the multiple facets of migrants' identities reflect the sociopolitical relationships within and between places. The resolution of these tensions is partially revealed in the hybridity and fluidity of migrants' articulation of their identities, whilst maintaining a primary identification with their culture of origin."     

首都圈遥测台网卫星传输台站数据流与传递函数

介绍了首都圈32个卫星台站的概况和数据传输的实现方法，阐述了数据采集器参数设定的有关问题，同时给出了不同类型地震仪测震观测技术指标。从原理上探讨了地震仪观测灵敏度和传递函数的测定方法，并对32个卫星传输台站传递函数的测定结果进行了分析。