Planform Island change assessment for inhabited Lakshadweep Islands

Natural Hazards - Impacts of coastal processes and anthropogenic activities threaten the archipelago of low-lying reef islands. In this study, long-term (1972–2015) and short-term...     

A baseline study of trace metals in a coral reef sedimentary environment,Lakshadweep Archipelago

Surficial and core samples collected from the sedimentary microenvironments of Lakshadweep Archipelago were analysed for their trace metal contents. The synoptical relations in spatial distributions with respect to environmental conditions such as pH, organic carbon and sediment texture were inter-correlated. Some of the metals exhibited good correlations with Fe/Mn, which reflect their similarity in distribution rather than anthropogenic enrichment. Inter-relating the variations in metal—pH relationships with metal—organic carbon, in general, those which exhibited positive correlations with pH, displayed negative interactions with organic carbon content and vice versa. Comparatively, higher values of Fe in the mangrove area of one of the islands highlight the possibility of precipitation of Fe as iron sulphides, which are common in mangrove ecosystem. Based on the contamination factors for Pb, Zn and Cd, as well as the geo-accumulation index of Cd, it can be generalised that some of the islands remain polluted with respect to these elements. An evaluation based on pollution load index shows that none of the islands surveyed for this study posed a serious threat in trace metal pollution. Bray Curtis similarity index was computed to find out the similarity among metals/islands, using non-transformed data of metal concentrations. Group linkage clustering technique was used for drawing dendrograms to show the similarity among them.     

某岩溶水源地地下水中有机氯农药的分布特征

某水源地的岩溶水是北方一大型城市的主要供水水源,为了解该区地下水中有机氯农药的分布情况,采用气相色谱法对某岩溶水源地76组地下水样进行了测试分析。研究结果表明:地下水中检出10种有机氯农药组分,检出率最高的是β-HCH,为11.84%;有机氯农药的检出质量浓度为0.96～63.77ng/L,平均值为13.50ng/L,远小于饮用水水质标准。在丰水期,地下水中检出的有机氯农药组分较多,检出质量浓度总体上是丰水期高于枯水期、补给区高于径流区和排泄区,并且质量浓度会随着地下水位的升高而变大。地下水中的有机氯农药主要来源于早期使用的农药在环境中的残留,γ-HCH则可能来自于开采井附近农药厂排放的污水。     

Groundwater management in France

Groundwater, like other extensive natural and renewable resources, easily accessible and, at the same time, vulnerable, has to be managed so as to reconcile the unique resource with its many users, and its long-term preservation with short-term utilization requirements. Under the natural, legal, and economic conditions prevailing in France, where groundwater constitutes a large part of water production and resources, where there are tens of thousands of economic developers and users of a few hundred natural groundwater management units, such management concerns these users as well as the public and collective authorities that control the users' activities for the common present and future good of all. Legislative, financial, and educational means are applied simultaneously to preserve and protect the quality and quantily of the groundwater and at times to encourage its use and stimulate its development.     

Tropical cyclone activity in global warming scenario

Research efforts focused on assessing the potential for changes in tropical cyclone activity in the greenhouse-warmed climate have progressed since the IPCC assessment in 1996. Vulnerability to tropical cyclones becoming more pronounced due to the fastest population growth in tropical coastal regions makes it practically important to explore possible changes in tropical cyclone activity due to global warming. This paper investigates the tropical cyclone activity over whole globe and also individually over six different ocean basins. The parameters like storm frequency, storm duration, maximum intensity attained and location of formation of storm have been examined over the past 30-year period from 1977 to 2006. Of all, the north Atlantic Ocean shows a significant increasing trend in storm frequency and storm days, especially for intense cyclones. Lifetime of intense tropical cyclones over south Indian Ocean has been increased. The intense cyclonic activity over north Atlantic, south-west Pacific, north and south Indian Ocean has been increased in recent 15 years as compared to previous 15 years, whereas in the east and west-north Pacific it is decreased, instead weak cyclone activity has been increased there. Examination of maximum intensity shows that cyclones are becoming more and more intense over the south Indian Ocean with the highest rate. The study of the change in the cyclogenesis events in the recent 15 years shows more increase in the north Atlantic. The Arabian Sea experiences increase in the cyclogenesis in general, whereas Bay of Bengal witnesses decrease in these events. Shrinking of cyclogenesis region occurs in the east-north Pacific and south-west Pacific, whereas expansion occurs in west-north Pacific. The change in cyclogenesis events and their spatial distribution in association with the meteorological parameters like sea surface temperature (SST), vertical wind shear has been studied for Indian Ocean. The increase in SST and decrease in wind shear correspond to increase in the cyclogenesis events and vice versa for north Indian Ocean; however, for south Indian Ocean, it is not one to one.     

Evidences for heavy metal contamination in surface sediments of seagrass ecosystem of Lakshadweep archipelago, India

Surface sediments of nine islands of Lakshadweep were evaluated for their heavy metal concentration (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn). Sediments of thirteen seagrass and seven non seagrass sites were collected randomly and analysed for heavy metal concentration using Inductively Coupled Plasma Optical Emission Spectrometer. Heavy metals like Cu, Ni and Zn were found in higher concentrations in the seagrass sediments, whereas other heavy metals such as Cd, Co, Cr, Fe, Mn and Pb were higher in non seagrass sediments. Different pollution indices were calculated to evaluate contamination level of all heavy metals in the sediments. Cadmium recorded higher contamination factor (1.733–21.067), enrichment factor (276.10–12,270) and Geo-accumulation Index (0.208–3.811) both in seagrass and nonseagrass sediments. Multivariate statistical analysis such as principal component analysis and cluster analysis coupled together with correlation co-efficient was used to identify the possible sources of heavy metal pollution in the region. Average concentrations of Cd in Lakshadweep islands were slightly higher than effective range, low but still below effective range medium. All other metals were still below these ranges indicating fairly uncontaminated sediment in the region.     

鄂尔多斯白垩系地下水盆地中深层地下水可更新速率

为了缓解鄂尔多斯能源基地的供水压力和为当地水资源评价、地下水合理开发利用提供依据,研究该区主要供水水源地的白垩系盆地地下水可更新能力。地下水中溶解无机碳的动力行为可以近似认为与地下水相同,因此,地下水系统中¹⁴C的输入、输出浓度可以提供地下水系统可更新能力的重要信息。利用鄂尔多斯白垩系地下水盆地中、深层地下水¹⁴C数据,以地下水更新速率为指标,通过同位素数学物理模型定量评价了盆地中、深层地下水的可更新能力。结果表明：研究区地下水可更新能力随埋藏深度的增大而减弱,中层地下水更新速率多为0.1%/a~1%/a,可更新能力较强;深层地下水更新速率绝大多数都小于0.1%/a,可更新能力较弱;盆地北区地下水可更新能力整体高于盆地南区。     

Groundwater contamination in Japan

Problems on groundwater contamination in Japan are briefly summarized in this paper. Although normal physical conditions in Japan restrict the possibilities of groundwater contamination, human activities are threatening groundwater resources. A survey by the Environment Agency of Japan showed nationwide spreading of organic substances, such as trichloroethylene as well as nitrogen compounds. Synthetic detergents have also been detected even in rural areas and in deep confined aquifers, although their concentrations are not as high. Public awareness of agrichemical or pesticides abuse, especially from golf courses, is apparent. Other problems such as nitrate-nitrogen, leachate from landfills, and the leaking of underground storage tanks are also discussed.     

金华地区地下水同位素特征及更新能力研究

金华地区位于金衢盆地东段,对其地下水同位素特征及更新能力研究对于整个盆地地下水资源研究具有重要意义,通过分析研究区内稳定同位素氘(D)和氧(~(18)O)以及放射性同位素氚(~3H)和碳(~(14)C)的空间分布特征,建立了金华地区降水线方程为:δD=8.29δ~(18)O+15.9,讨论了地表水、潜水、红层地下水的环境同位素的组成特征,对潜水及红层地下水的更新能力进行了评价。结果表明,金华地区降水线方程斜率及截距均大于全球大气降水;潜水、红层地下水及地表水三者联系密切;潜水、红层地下水在接受降水的补给后经历了不同程度的蒸发作用;红层地下水D和~(18)O同位素明显向下游富集;潜水~3H值介于6.6～19.0TU,~(14)C年龄显示为现代水,因此其可更新能力较强,红层地下水放射性~(14)C年龄为3020～5360BP,可更新能力较弱,红层地下水3H值介于4.4～12.3TU,表明红层地下水中有现代水的混入,δ~(18)O随着地下水的年龄的增加而偏负。     

Geology in the Falkland Islands

In the next few years we are likely to hear and learn much about the offshore geology of the Falkland Islands as exploratory drilling for hydrocarbons begins. The offshore geology may become better known than the onshore, of which there has been little detailed investigation in the 200+ years since settlements were established. Here we outline the history of geological investigations and present information gathered during recent fieldwork.     

Stars with relativistic speeds in the Hills scenario

The dynamical capture of a binary system consisting of a supermassive black hole (SMBH) and an ordinary star in the gravitational field of a central (more massive) SMBH is considered in the three-body problem in the framework of a modified Hills scenario. The results of numerical simulations predict the existence of objects whose spatial speeds are comparable to the speed of light. The conditions for and constraints imposed on the ejection speeds realized in a classical scenario and the modified Hills scenario are analyzed. The star is modeled using an N-body approach, making it possible to treat it as a structured object, enabling estimation of the probability that the object survives when it is ejected with relativistic speed as a function of the mass of the star, the masses of both SMBHs, and the pericenter distance. It is possible that the modern kinematic classification for stars with anomalously high spatial velocities will be augmented with a new class—stars with relativistic speeds.     

CFCs法在鄂尔多斯白垩系地下水盆地浅层地下水年龄研究中的应用

鄂尔多斯白垩系地下水盆地是中国重要的能源基地,利用CFCS方法对鄂尔多斯白垩系地下水盆地年轻地下水年龄进行测定,取得了比较准确的结果。结果表明,盆地地下水系统可以分为局部地下水系统、中间地下水系统和区域地下水系统。地下水盆地内局部地下水系统地下水循环更替快,年龄为20 a左右,地下水年龄随深度增加而增加;中间地下水系统和区域地下水系统地下水循环更替相对较慢,年龄大于70 a,可以寻求14C等其他同位素方法确定准确年龄。     

Groundwater in a coral island

 Freshwater aquifers in small coral islands usually occur as thin lenses which are significantly influenced by stresses such as groundwater pumping, sea tides, etc. Kavaratti, a coral island, is one of the 36 such islands in the Arabian Sea off the western coast of India. Detailed hydrogeological investigations were carried out to determine the quantity of freshwater that could be pumped in addition to the present usage. Salinity of groundwater must remain within permissible limits and a 2-D solute mass transport model with a vertical section of the island was constructed by the computer code SUTRA. The model was calibrated by obtaining a match of computed and observed values of the water table, tidal efficiency, and salinity of groundwater at the water table. The model analysis showed that the salinity of groundwater continues to increase unless groundwater pumping is kept below a certain rate. Groundwater potential can be augmented by reducing the subsurface outflow to the sea and by raising the water table by a subsurface dam. Received: 8 September 1997 · Accepted: 27 April 1998     

Groundwater quality Management in China

Groundwater quality is of vital importance in groundwater safety especially for the purpose of water supply, its management becomes more and more necessary as groundwater contamination has threaten its safe use in China. The article analyzed the contamination sources of groundwater and impact of contamination on human health and water supply, the knowledge gaps were pointed and recommendations were made for groundwater quality management in China.     

沿岸地下水排放通量

海岸带地区,陆源物质由近岸向沿岸海洋输送的途径有很多,而在一些海岸或海湾,其中较普遍的一个过程就是海底地下水排放。它是发生在沿岸地区与毗邻海洋之间的又一个重要的陆海相互作用过程。目前,通过水文、直接测量和地球化学示踪法研究地下水排放的例子有很多,但对其进行定量估算仍面临着许多困难。本文主要介绍镭同位素地球化学示踪法的基本原理及应用,以海南东北部沿岸水域中镭同位素数据为例,计算得到相应的地下水排放通量为5.4×10-4dm3/(d.cm2)。     

Groundwater management in northern Iraq

Groundwater is vital and the sole resource in most of the studied region of northern Iraq. It has a significant role in agriculture, water supply and health, and the elimination of poverty in rural areas. Although Iraq is currently dramatically disturbed by complex political and socio-economic problems, in its northern part, i.e. the Kurdish-inhabited region, fast urbanization and economic expansion are visible everywhere. Monitoring and water management schemes are necessary to prevent aquifer over-exploitation in the region. Artificial recharge with temporary runoff water, construction of subsurface dams and several other aquifer management and regulation measures have been designed, and some implemented, in order to improve the water situation. Recommendations, presented to the local professionals and decision-makers in water management, include creation of Water Master Plans and Water User Associations, synchronization of drilling programmes, rehabilitation of the existing well fields, opening of new well fields, and the incorporation of new spring intakes in some areas with large groundwater reserves, as well as construction of numerous small-scale schemes for initial in situ water treatment where saline groundwater is present.     

Stone runs in the Falkland Islands

Large parts of the Falkland Islands are covered by conspicuous stone stripes. Their appearance is believed to be the result of partial vegetation cover developing on solifluction-transported rock.