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Three dimensional diagnostic study of the circulation in the South China Sea during winter 1998

On the basis of hydrographic data obtained from 28 November to 27 December, 1998, the three-dimensional structure of circulation in the South China Sea (SCS) is computed using a three-dimensional diagnostic model. The combination of sea surface height anomaly from altimeter data and numerical results provides a consistent circulation pattern for the SCS, and main circulation features can be summarized as follows: in the northern SCS there are a cold and cyclonic circulation C1 with two cores C1-1 and C1-2 northwest of Luzon and an anticyclonic eddy (W1) near Dongsha Islands. In the central SCS there is a stronger cyclonic circulation C2 with two cores C2-1 and C2-2 east of Vietnam and a weaker anticyclonic eddy W2 northwest of Palawan Island. A stronger coastal southward jet presents west of the eddy C2 and turns to the southeast in the region southwest of eddy C2-2, and it then turns to flow eastward in the region south of eddy C2-2. In the southern SCS there are a weak cyclonic eddy C3 northwest of Borneo and an anti-cyclonic circulation W3 in the subsurface layer. The net westward volume transport through section CD at 119.125°E from 18.975° to 21.725°N is about 10.3 × 10⁶ m³s⁻¹ in the layer above 400 m level. The most important dynamic mechanism generating the circulation in the SCS is a joint effect of the baroclinicity and relief (JEBAR), and the second dynamical mechanism is an interaction between the wind stress and relief (IBWSR). The strong upwelling occurs off northwest Luzon.     

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北冰洋航海线在世界地图上的表示及相关讨论

介绍根据《系列世界地图》提出的“北冰洋是世界地中海”的新观念,讨论了全球变暖后北冰洋凸显出的战略意义。通过对东京到伦敦的“苏伊士航海线”、“巴拿马航海线”、“好望角航海线”和“北冰洋航海线”的对比分析,展现“北冰洋航海线”表示在“北半球版世界地图”上的优越性。     

远海梭子蟹幼体饵料初步研究

分别选用轮虫、轮虫 卤虫、轮虫 卤虫 扁藻、卤虫、扁藻为饵料 ,将刚孵化的远海梭子蟹氵蚤状幼体培育至幼蟹第二期。结果发现 :轮虫 卤虫 扁藻的效果最好 ,幼蟹第二期的成活率为 15% ,轮虫 卤虫的成活率为 11% ,卤虫的成活率为 10 %。而轮虫组仅能培育至 氵蚤状幼体第三期 ,没有氵蚤状幼体第四期幼体出现 ;扁藻最差 ,仅能培育至氵蚤状幼体第一期 ,没有氵蚤状幼体第二期个体出现。同时发现 ,轮虫 卤虫组与卤虫组培育时间均比轮虫卤虫 扁藻组长 ;各期幼体的阶段成活率比较而言 ,氵蚤状幼体第一期最高 ,而氵蚤状幼体幼体第五期最低     

Gold and antimony metallogenic relations and ore-forming process of Qinglong Sb(Au) deposit in Youjiang basin,SW China:Sulfide trace elements and sulfur isotopes

In the northwestern margin of the Youjiang basin(NWYB)in SW China,many Carlin-like gold deposits are highly antimony(Sb)-rich,and many vein-type Sb deposits contain much Au.These deposits have similar ages,host rocks,ore-forming temperatures,ore-related alterations and ore mineral assemblages,but the Au and Sb metallogenic relations and their ore-forming process remain enigmatic.Here we investigate the large Qinglong Sb deposit in the NWYB,which has extensive sub-economic Au mineralization,and present a new metallogenic model based on in-situ trace elements(EPMA and LA-ICP-MS)and sulfur isotopes(NanoSIMS and fs-LA-MC-ICPMS)of the ore sulfides.At Qinglong,economic Sb ores contain coarse-grained stibnite,jasperoid quartz and fluorite,whilst the sub-economic Au–Sb ores comprise dominantly veined quartz,arsenian pyrite and fine-grained stibnite.Three generations of ore-related pyrite(Py1,Py2 and Py3)and two generations of stibnite(Stb1 and Stb2)are identified based on their texture,chemistry,and sulfur isotopes.The pre-ore Py1 is characterized by the lower ore element(Au,As,Sb,Cu and Ag)contents(mostly below the LA-ICP-MS detection limit)and Co/Ni ratios(average 0.31)than the ore-stage pyrites(Py2 and Py3),implying a sedimentary/diagenetic origin.The Py2 and Py3 have elevated ore element abundance(maximum As=6500 ppm,Au=22 ppm,Sb=6300 ppm,Cu=951 ppm,Ag=77 ppm)and Co/Ni ratios(average 1.84),and have positive As vs.Au–Sb–Cu–Ag correlations.Early-ore Stb1 has lower As(0.12–0.30 wt.%)than late-ore Stb2(0.91–1.20 wt.%).These features show that the progressive As enrichment in ore sulfides is accompanied by increasing Au,Sb,Cu and Ag with the hydrothermal evolution,thereby making As a good proxy for Au.As-rich,As-poor and As-free zones are identified via NanoSIMS mapping of the Au-bearing pyrite.The As-rich zones in the Qinglong Au-bearing pyrites(Py2 and Py3)and ore stibnites(Stb1 and Stb2)have narrowδ³⁴SH₂S ranges(-8.9‰to +4.1‰,average-3.1‰)and-2.9‰to +6.9‰,average + 1.3‰),respectively,indicating that the Au-rich and Sb-rich fluids may have had the same sulfur source.Published in-situ sulfur isotopic data of pyrite As-rich zones from other Carlin-like Au deposits(Shuiyindong,Taipingdong,Nayang,Getang and Lianhuashan)in the NWYB have similar ore-fluidδSH₂S values(-4.5‰to +6.7‰,average-0.6‰)to those of Qinglong.Therefore,we infer that the sulfur of both Au and Sb mineralization was derived from the same magmatic-related source(0±5‰)in the NWYB.Moreover,the core of pyrites(Py1)has variable S isotope fractionation(-18.9‰to +18.1‰,mostly +3‰to +12‰),suggesting that the higher-³⁴S H₂S was produced by bacterial sulfate reduction(BSR).The hydrothermal pyrite(Py2 and Py3)δ³⁴S values gradually decrease with increasing As concentrations,and ultimately,within the restricted range(-5‰to +5‰)in As-rich zones.This variation implies that the As-rich pyrite was formed through ongoing interactions of the magmatic-hydrothermal fluid with pre-existing sedimentary pyrites,causing the progressive decreasing δ³⁴S values with As content increase,Hence,the fluid/mineral interaction may have generated the observed variation in δ³⁴S and As contents.Overall,comparing the Au and Sb deposits in the NWYB,we favor a magmatic-related source for the Au–Sb–As-rich fluids,but the Au-and Sb-ore fluids were likely evolved at separate stages in the ore-forming system.     

广西近50年暴雨日数变化的小波分析

利用1951—2005年广西降水资料,使用Morlet小波分析方法分析了暴雨和大暴雨日数的年际变化,结果表明均具有明显的周期变化规律特征,都存在着2、4、8、14年周期振荡信号,其中2年周期振荡信号最强,其次为4,8,14年,各周期信号分布的时间区域略有差异。广西暴雨日数变化总趋势为逐渐增多,在1990年代进入高峰期。影响广西暴雨发生的主要天气系统为热带气旋、西南低涡、低空急流、高空槽,其中热带气旋、西南低涡是广西特大暴雨发生的主要原因。     

大型水库分层期和混合期溶存温室气体空间变化及排放通量

水库作为温室气体的重要来源,对区域气候变化有不可忽略的影响。然而,目前对水库溶存温室气体的空间异质性及垂向特征的认知仍然欠缺。为了揭示水库分层期和混合期溶存温室气体空间特征及排放通量,也为厘清水库温室气体产生和排放的关键过程提供重要支撑。研究选择东北地区大型水库——汤河水库为对象,于2021年7—9月和10月(分别代表水库分层期和混合期)对水库不同位置(坝前、库中和库尾)开展溶存温室气体垂向分层监测。研究结果显示,水库CH₄排放通量变化范围为0.018～0.174 mmol/(m²·d),是大气CH₄的源,空间分布为库尾>库中>坝前;CO₂通量为-4.91～58.77 mmol/(m²·d),除分层期东支库尾,其余点位均表现为大气CO₂的源,空间分布为坝前>库中>库尾。时间上,分层期CH₄排放通量(0.071±0.044 mmol/(m²·d))高于混合期((0.027±0.008) mm...     

城市场次降雨径流污染负荷快速估算方法

城市降雨径流污染是城市水质恶化的重要原因之一,定量计算城市降雨径流污染负荷,是实施城市水环境污染总量控制管理的基础和关键,可为城市水环境治理和污染控制提供科学依据.本文以污染物累积冲刷理论为基础,提出了“特征面积”的概念和计算公式,建立了场次降雨径流污染负荷数学模型,并结合案例,对数学模型在有效性、预测精度、适用性和局限性等方面进行评价.结果表明,特征面积较好地反映了污染物在各类土地上的污染负荷特性,场次降雨径流污染负荷与特征面积和降雨量的乘积呈正比.利用3场及以上降雨径流污染负荷结果,可较好地率定模型,从而可快速且较准确地估算单场次降雨径流污染负荷.该方法简单实用,获取数据工作量小,适用地区广.对于小降雨事件,建议采用降雨量相近的观测结果对模型进行率定,以提高模型的预测精度.