‘Thermohaline front’ off the east coast of India and its generating mechanism

Physical oceanography measurements reveal a strong salinity (0.18 psu km⁻¹) and temperature (0.07 °C km⁻¹) front off the east coast of India in December 1997. T–S diagrams suggest lateral mixing between the fresh water at the coast and the ambient warmer, saltier water. This front seems to be the result of southward advection of fresh and cool water, formed in the northern Bay of Bengal during the monsoon, by the East Indian Coastal Current, as suggested by the large-scale salinity structure in the SODA re-analysis and the anti-cyclonic gyre in the northwestern Bay of Bengal during winter. The data further reveals an offshore front in January, which appears to be the result of a meso-scale re-circulation around an eddy, bringing cold and freshwater from the northern Bay of Bengal further away from the shore. Our cruise data hence illustrates that very strong salinity fronts can appear in the Bay of Bengal after the monsoon, as a result of intense coastal circulation and stirring by eddies.

     

Role of Nitrogen Oxides,Black Carbon,and Meteorological Parameters on the Variation of Surface Ozone Levels at a Tropical Urban Site – Hyderabad,India

In this study, temporal variations of surface ozone (O₃) were investigated at tropical urban site of Hyderabad during the year 2009. O₃, oxides of nitrogen (NO_x = NO + NO₂), black carbon (BC), and meteorological parameters were continuously monitored at the established air monitoring station. Results revealed the production of surface O₃ from NO₂ through photochemical oxidation. Averaged datasets illustrated the variations in ground‐level concentrations of these air pollutants along different time scales. Maximum mean concentrations of O₃ (56.75 ppbv) and NO_x (8.9 ppbv) were observed in summer. Diurnal‐seasonal changes in surface O₃ and NO_x concentrations were explicated with complex atmospheric chemistry, boundary layer dynamics, and local meteorology. In addition, nocturnal chemistry of NO_x played a decisive role in the formation of O₃ during day time. Mean BC mass concentration in winter (10.92 µg m^?3) was high during morning hours. Heterogeneous chemistry of BC on O₃ destruction and NO_x formation was elucidated. Apart from these local observations, long‐range transport of trace gases and BC aerosols were evidenced from air mass back trajectories. Further, statistical modeling was performed to predict O₃ using multi‐linear regression method, which resulted in 91% of the overall variance.     

多波束测深系统内部参数的设定与校准

以EM710RD多波束测深系统为例,通过高精度测量获得的系统参数,对该系统内部参数的设定与校准过程进行详细分析,从而为多波束测量外业工作提供参考依据。     

冀北火山岩型铀矿地球化学评价指标研究

冀北地区是火山岩型铀矿的有利产出区域,本文以该区的水系沉积物区域化探数据与典型铀矿矿区岩石和土壤地球化学数据为研究基础,建立适用于火山岩型铀矿的地球化学勘查评价指标。含矿围岩富铀、钍、硅、钾。铀富集于粗粒级(-4～+20目)水系沉积物和细粒级(-100目)土壤。因此,粗粒级水系沉积物是区域测量的有效采样介质,细粒级土壤是矿区测量的有效采样介质。火山岩型铀矿直接的特征指示元素为U和Mo,其它伴生元素还有Th、La、Hg、Sb、Zr、B、F等。该指标的建立对冀北地区及北方火山岩型铀矿勘查评价具有实际意义。     

山东半岛东北部新发现近EW向活断层

山东半岛东北部地区晚第四纪的构造活动以整体性抬升为主,内部的断裂活动相对较弱,晚更新世以来的断裂活动仅分布在局部地区,新发现的东殿后断裂是其中的1条。断裂总体走向近EW,全长约20km,地貌上表现为由3条河流上游组成的谷地。断裂错断的最新地层的热释光年龄为84～75kaBP,上覆坡积角砾层的热释光年龄为64kaBP,断裂发育的松软断层泥的热释光年龄为82kaBP。断裂的剖面特征和断盖地层的年龄表明,东殿后断裂的最新活动时代是晚更新世早中期,垂直活动速率不<016mm/a,晚更新世晚期以来停止活动;断裂的最大潜在地震为6级     

Modelling of Riparian-Imitated Constructed Wetland for Fish Habitat

This paper presents a hydrodynamic-based investigation of constructed wetland suitability for fish habitat. A constructed wetland adjacent to river is manoeuvred to imitate riparian fish habitat by means of computer modelling. Flow-velocity conditions, water depths and effects of macrophytes to resistance of flow in constructed wetland are modelled and steered towards creating a favourable ground for natural substrate spawning of native fish species. The model suggests combination of two zones, which are a macrophyte zone for typical functions of a wetland and an open water zone with gravel bed to support fish reproductive cycles.     

Significance of nearshore wave parameters in identifying vulnerable zones during storm and normal conditions along Visakhapatnam coast,India

The nearshore parameters, viz., wave runup, wave setup, and wave energy have been estimated during storm and normal conditions of SW monsoon (June–September) and NE monsoon (November–February) by empirical parameterization along Visakhapatnam coast. These results were compared with the field observations during three storms of SW monsoon season in the year 2007. The higher nearshore wave energies were observed at R.K. Beach, Jodugullapalem beach, and Sagarnagar beach during both the seasons. During storm events, the higher wave energies associated with higher wave runups cause severe erosion along the wave convergence zones. The storm wave runups (SWRUs) were higher at R.K. Beach, Palm beach, Jodugullapalem beach, and Sagarnagar Beach. The yearly low wave energy was observed at Lawson’s Bay with lowest wave runup, considered as safest zone. R.K. Beach, Palm beach, and Jodugullapalem beach are identified as vulnerable zones of wave attack. It is noteworthy that in addition to wave energies, wave runups and wave setups also play a vital role in endangering the coast.     

澜沧老厂铅锌矿巷道围岩工程地质特征分析及质量评价

地质力学分类方法是目前工程地质围岩分类中综合多因素分类方法中较常见的一种。它主要是通过完整的岩石强度、岩石质量指标（RQD）、节理间距、节理状态和地下水条件这五个参数来对岩体进行量化打分,最终通过总得分来对围岩进行分类。本文就是通过该分类方法对澜沧老厂铅锌矿的巷道围岩进行质量评价。     

一次触发闪电地电位抬升引发的氧化锌电涌保护器损坏事件分析

基于触发闪电开展了电流注入地网后地电位抬升反击氧化锌电涌保护器的试验研究.结合真实雷电环境下测量的电涌保护器两端残压和流经电流的数据,对一次触发闪电引发的氧化锌电涌保护器损坏事件进行了分析.分析发现,电流注入地网后,回击过程瞬间的大能量和长连续电流过程累积的能量相互叠加共同作用损坏了氧化锌电涌保护器.回击发生时,较大的...     

江西兴国县潜在偏硅酸矿泉水水化学特征及水质健康功能评价

江西兴国县地下水中富含偏硅酸,水资源丰富,但对矿泉水资源禀赋等研究相对薄弱,开展该县偏硅酸矿泉水水化学特征和健康功能研究,可为当地发展矿泉水产业、实施乡村振兴战略提供基础支撑。本文应用数理统计、水化学分析、离子比值等多种分析方法研究了兴国县潜在偏硅酸矿泉水的分布、水化学特征以及成因与物质来源,并基于感官指数和健康指数对其健康功能进行了评价。结果表明：潜在偏硅酸矿泉水主要分布在岩浆岩裂隙含水岩组、碎屑岩孔隙裂隙含水岩组和变质岩裂隙含水岩组中,这三类含水岩组的调查水样中,发现潜在偏硅酸矿泉水的比例分别为48.5%、45.7%、29.6%,且主要分布在海拔400m以下区域。潜在偏硅酸矿泉水的偏硅酸含量多集中在32~40mg/L之间,主要来自硅酸盐矿物的水解;在变质岩、岩浆岩裂隙含水岩组区,偏硅酸的富集以溶滤作用为主;在碎屑岩孔隙裂隙含水岩组区,偏硅酸的富集受溶滤作用和阳离子交替吸附作用共同影响。该县岩浆岩裂隙含水组区潜在偏硅酸矿泉水口感最佳,深层碎屑岩孔隙含水组区潜在偏硅酸矿泉水健康指数相对较高。本文认为,兴国县矿泉水勘查开发靶区宜以岩浆岩裂隙含水岩组区和深层碎屑岩孔隙裂隙含水岩组区为主。研究成果可为揭示兴国县偏硅酸矿泉水资源价值和功能提供参考。