Appraisal of the carbon to nitrogen(C/N)ratio in the bed sediment of the Betwa River,Peninsular India

Bed sediment carbon to nitrogen(C/N) ratio is one of the essential variables reflecting sources of organic matter in river basins.In order to explore the spatial variability in sources of sediment C/N ratios,and the influence of land use and land cover(LULC) changes on the Betwa River basin in Peninsular India,51 river bed sediment samples were collected in December 2016.The coefficient of variation(CV) was35%indicating highly variable biogeochemical parameters.The sediment C/N ratio varied from 2.94 to 10.09.3.21-56.40,and 6.50-76.97 in upstream,mid-stream,and downstream regions,respectively,indicating a progressive change in sources of organic matter and depositional environment.The positive correlation between total carbon(TC) and C/N ratio was increasing in the downstream direction [upstream(+0.560) mid-stream(+0.603) downstream(+0.838)],which is an indication of high deposition and slow decomposition of sedimentary terrigenous organic matter distant from the regions of urban pollution.The LULC change analysis done by remote sensing and Geographic Information System(GIS)methods revealed an adverse change for the forests and barren land and a positive change for the agricultural land and built-up areas.The sediment C/N ratio mapping showed the impact of LULC changes on the sediment quality.The spatial distribution of bed sediment C/N ratio in the Betwa River basin has important reference value for managing organic matter transport in the downstream Yamuna River and Ganga River basin.     

Plate kinematics, origin and tectonic emplacement of supra-subduction ophiolites in SE Asia

A unique feature of the Circum Pacific orogenic belts is the occurrence of ophiolitic bodies of various sizes, most of which display petrological and geochemical characteristics typical of supra-subduction zone oceanic crust. In SE Asia, a majority of the ophiolites appear to have originated at convergent margins, and specifically in backarc or island arc settings, which evolved either along the edge of the Sunda (Eurasia) and Australian cratons, or within the Philippine Sea Plate. These ophiolites were later accreted to continental margins during the Tertiary. Because of fast relative plate velocities, tectonic regimes at the active margins of these three plates also changed rapidly. Strain partitioning associated with oblique convergence caused arc-trench systems to move further away from the locus of their accretion. We distinguish “relatively autochthonous ophiolites” resulting from the shortening of marginal basins such as the present-day South China Sea or the Coral Sea, and “highly displaced ophiolites” developed in oblique convergent margins, where they were dismantled, transported and locally severely sheared during final docking. In peri-cratonic mobile belts (i.e. the Philippine Mobile Belt) we find a series of oceanic basins which have been slightly deformed and uplifted. Varying lithologies and geochemical compositions of tectonic units in these basins, as well as their age discrepancies, suggest important displacements along major wrench faults.We have used plate tectonic reconstructions to restore the former backarc basins and island arcs characterized by known petro-geochemical data to their original location and their former tectonic settings. Some of the ophiolites occurring in front of the Sunda plate represent supra-subduction zone basins formed along the Australian Craton margin during the Mesozoic. The Philippine Sea Basin, the Huatung basin south of Taiwan, and composite ophiolitic basements of the Philippines and Halmahera may represent remnants of such marginal basins. The portion of the Philippine Sea Plate carrying the Taiwan–Philippine arc and its composite ophiolitic/continental crustal basement might have actually originated in a different setting, closer to that of the Papua New Guinea Ophiolite, and then have been displaced rapidly as a result of shearing associated with fast oblique convergence.     

Coral bleaching on high-latitude marginal reefs at Sodwana Bay,South Africa

Coral bleaching, involving the expulsion of symbiotic zooxanthellae from the host cells, poses a major threat to coral reefs throughout their distributional range. The role of temperature in coral bleaching has been extensively investigated and is widely accepted. A bleaching event was observed on the marginal high-latitude reefs of South Africa located at Sodwana Bay during the summer months of 2000. This was associated with increased sea temperatures with high seasonal peaks in summer and increased radiation in exceptionally clear water. The bleaching was limited to Two-mile Reef and Nine-mile Reef at Sodwana Bay and affected <12% of the total living cover on Two-mile Reef. Montipora spp., Alveopora spongiosa and Acropora spp. were bleached, as well as some Alcyoniidae (Sinularia dura, Lobophytum depressum, L. patulum). A cyclical increase in sea temperature (with a period of 5–6 years) was recorded during 1998–2000 in addition to the regional temperature increase caused by the El Niño Southern Oscillation phenomenon. The mean sea temperature increased at a rate of 0.27 °C year⁻¹ from May 1994 to April 2000. High maximum temperatures were measured (>29 °C). The lowest mean monthly and the mean maximum monthly temperatures at which coral bleaching occurred were 27.5 and 28.8 °C, respectively, while the duration for which high temperatures occurred in 2000 was 67 days at 27.5 °C (4 days at 28.8 °C). Increased water clarity and radiation appeared to be a synergistic cause in the coral bleaching encountered at Sodwana Bay.     

地图扫描数字化中的地图自动定向方法

提出并实现了二值图像上十字交点的沿线匹配算法，发展了一种根据相关位置自动识别图廓点，进而计算图像坐标系和大地坐标系之间变换参数的方法，实现了地图定向的自动化。实验表明，文中所述的地图定向方法在提高自动化程度的同时，也提高了地图定向的精度。     

Long-term benthic population changes (1920–1930s-present) in the Barents and Kara Seas

Bottom sediment was analysed, via grab, trawl and underwater photography in 1991–1992 in the Barents, White, Kara, Norwegian and Greenland Seas, and the large scale features of macrobenthos distribution are described. The maps of alpha-diversity, biomass and trophic zone distribution on the investigated shelf are presented. Statistical assessment of the bottom community structure changes during the last 60–70 years for the Barents Sea area is presented. It is shown that on regional and transregional levels the researched communities are of natural undisturbed character and that the revealed changes may be both the result of natural processes or sampling errors. Local disturbances of benthos composition and structure, supposedly caused by man, are found to be rare not far from the Novaya Zemlya and Murman coasts.     

华南及其相邻边缘海域一些重要断裂的地球物理证据

通过对华南及其相邻的边缘海域的布格重力异常和磁力数据的处理和分析，利用水平方向导数、小波变换及典型剖面反演的共同结果，在研究区中分辨出方向各异的主要断裂共39条，根据重磁异常特征并结合层析成像结果分析了研究区内断裂的分布与延伸，特别对红河断裂带等重要断裂进行了重点讨论，并探讨了它们的延伸及与周边各地质单元之间的关系。     

Wave-ice interaction in the North-West Barents Sea

The results of field work on drift ice during wave propagation are analyzed and presented. The field work was performed in the Barents Sea, and the main focus of the paper is on wave processes in the MIZ. A model of wave damping in broken ice is formulated and applied to interpret the field work results. It is confirmed that waves of higher frequencies are subjected to stronger damping when they propagate below the ice. This reduces the frequency of most energetic wave with increasing distance from the ice edge. Difference of wave spectra measured in two relatively close locations within the MIZ is discussed. The complicated geometry and dynamics of the MIZ in the North-West Barents Sea allow waves from the Atlantic Ocean and south regions of the Barents Sea to penetrate into different locations of the MIZ.     

Catalogue of Polychaete species(Annelida) described from China Seas during 2008–2017

China Seas are one of the most diverse regions in the Pacific. Though much eff ort has been made to explore its biodiversity, the polychaetes diversity is still poorly known. A large number of species records are based on ecological investigation rather than taxonomical studies. We update the Polychaete species taxonomicaly described from China coastal waters during 2008–2017 and list them as a catalogue. The catalogue contains 47 species of 32 genera and 17 families, the type depository, type locality and geographic distribution. Some taxonomic problems are present in remarks.     

A model for the conservation of geological remains as documents

 Geological remains are conserved mainly either together with living beings for the sake of the integrity of nature or for their economical or aesthetic value. However, they also have scientific value for the geologist to reconstruct the earth's past. For this reason we propose a model which is an application of marginal utility theory in economics and takes into account the informational utility of geological remains. Informational utility of geological remains ranges over their geological significance which is induced by the importance of the geological processes that produce them, and over their spatial extensiveness. Our model takes into account also the cost and budget of conservation and proposes to solve the differential equations of informational utility and cost simultaneously in order to obtain the optimum quantity of the remains to be conserved. Received: 9 January 1998 · Accepted: 4 February 1998     

近岸带波高与周期分布的核密度估计

使用双变量核密度估计方法描述近岸带波高和周期联合概率密度分布与波高、周期边缘密度分布。结果表明,核密度估计方法比通常使用的参数模式能更好地显示出具有多峰的波要素统计结构,核密度估计的波周期带宽系数能反映波浪谱的某些信息,尤其以波周期带宽和谱宽参量具有良好的线性关系。