向海湿地元素地球化学特征与高分辨沉积记录

以内流河下游漫流区-向海沼泽湿地为研究对象,对其典型剖面沉积物的柱状样以厘米级间距采样,在多元统计分析的基础上,结合¹³⁷Cs、²¹⁰Pb测年数据对其进行高分辨率元素地球化学特征解析,以获取现代沉积记录及其与流域环境变化的关系。结果表明,主成分分析提取的第一主成分有较高的代表性;聚类分析将元素按造岩、迁移累积型、强烈迁移型元素归为三类;大多数金属元素之间存在着显著相关性,并且均与TOC、<63?μm粒径的颗粒呈正相关。典型剖面金属元素的高分辨沉积记录解析表明:向海的沼泽发育可以追溯至1885年之前;1885年左右区域环境发生过突变;近250年以来,暖湿气候与风沙、干旱交替出现;研究区沼泽湿地沉积物表层沉积序列内已明显富集了重金属元素,近年霍林河流域上游人类活动对下游湿地的扰动增强。     

青藏高原西部地面反射率的日变化以及与若干气象因子的关系

根据1997年10月至1998年11月青藏高原西部改则和狮泉河两个自动气象站连续观测的大气、辐射和土壤资料,在分析高原西部地面反射率冬、夏季日变化特征的基础上,重点研究了地面反射率与土壤和大气若干重要因子(如土壤湿度、土壤温度、空气相对湿度、空气温度)的关系。研究结果有助于改进气候模式和卫星遥感中高原地面反射率的参数化方案。     

On the modeling of wave propagation on non-uniform currents and depth

By transforming two different time-dependent hyperbolic mild slope equations with dissipation term for wave propagation on non-uniform currents into wave-action conservation equation and eikonal equation, respectively, shown are the different effects of dissipation term on the eikonal equation in the two different mild slope equations. The performances of intrinsic frequency and wave number are also discussed. Thus the suitable mathematical model is chosen in which the wave number vector and intrinsic frequency are expressed both more rigorously and completely. By using the perturbation method, an extended evolution equation, which is of time-dependent parabolic type, is developed from the time-dependent hyperbolic mild slope equation which exists in the suitable mathematical model, and solved by using the alternating direction implicit (ADI) method. Presented is the numerical model for wave propagation and transformation on non-uniform currents in water of slowly varying topography. From the comparisons of the numerical solutions with the theoretical solutions of two examples of wave propagation, respectively, the results show that the numerical solutions are in good agreement with the exact ones. Calculating the interactions between incident wave and current on a sloping beach [Arthur, R.S., 1950. Refraction of shallow water waves. The combined effects of currents and underwater topography. EOS Transactions, August 31, 549–552], the differences of wave number vector between refraction and combined refraction–diffraction of waves are discussed quantitatively, while the effects of different methods of calculating wave number vector on numerical results are shown.     

印度尼西亚群岛成矿带划分及区域成矿特征

通过近年来对印度尼西亚的地层、构造、岩浆及矿产研究,在大地构造单元划分基础上,本文将印度尼西亚划分为3个一级成矿域(特提斯成矿域、环太平洋成矿域、印度-澳大利亚成矿域)、4个二级成矿省(苏门答腊岛成矿省、加里曼丹成矿省、苏拉威西成矿省、新几内亚成矿省)和9个三级成矿带,并对各成矿带的地质及成矿特征进行了简单阐述。     

Point source identification using a simple permutation test: a case study of elevated PCDD/F levels in ambient air and soil and their relation to the distance to a local municipal solid waste incinerator

A point source for environmental pollution may be identified by the spatial association of samples collected in the vicinity of the emission source. In this study, we used a simple permutation test to explore the spatial correlations between the ambient air and soil polychlorinated dibenzo-p-dioxin/dibenzofuran (PCDD/F) congener profile concentrations and their distances to a municipal solid waste incinerator (MSWI) in northern Taiwan. Kendall’s τ was applied for the correlation between the PCDD/F concentrations of a total of 9 airborne and 12 soil sampling sites and their distances to the incinerator. The results showed that the correlation was highly negatively associated for soil PCDD/Fs (τ = −0.515, p-value = 0.011) and was marginal for airborne PCDD/Fs (τ = −0.667, p-value = 0.055), conditional on the seasonal wind attributions. For the 17 individual congener profiles, most of the air and soil samples had a negative association, with 7 and 10 reaching statistical significance (p-value < 0.05) or borderline significance (0.05 < p-value < 0.10), respectively. The permutation test provides a simple and robust statistical method for the identification of a potential pollution source from a limited sample size. Our analytical results show that dioxin emissions from the investigated MSWI had a definite environmental impact on the surrounding area.     

三江平原沼泽土中多环芳烃分布及火烧的影响

为了研究三江平原沼泽土中多环芳烃(PAHs)的分布,采用气相色谱—质谱法(GC-MS)对沼泽土中16种优控多环芳烃污染物进行分析。结果表明,该区沼泽土中共检测出萘、苊烯、苊、芴、菲、蒽、荧蒽和芘8种PAHs,其总含量为365.4～975.4ng/g,平均值为(850.7±126.2)ng/g。与中国东北其他地区沼泽土相比,其低于长白山和大兴安岭摩天岭雨养泥炭沼泽土中的PAHs含量。检测出的PAHs以低环为主,在不同成分中萘、芴、菲的含量较高;不同采样点中,有火烧迹象沼泽土中的PAHs含量高于无火烧迹象的沼泽土。为验证火烧的影响,进行了土壤热处理后PAHs变化的试验,结果显示,经热处理后的沼泽土中PAHs的总量及各成分的含量均高于未经热处理的沼泽土。火烧是影响三江平原沼泽土中PAHs含量的重要因素之一。     

拉萨盆地曲水-夺底剖面大地电磁测深研究

通过对拉萨盆地曲水-夺底大地电磁测深剖面的研究,揭示了拉萨盆地深部地质构造特征.上地壳广泛分布花岗岩体,莫霍面深度大约70 km.壳内发育一个高导层,其顶界面埋深呈现南深北浅特点,厚度大约20～30 km,桑达附近存在一条深大断裂.     

Satellite RFI mitigation on FAST

As the most sensitive single-dish radio telescope,the Five-hundred Aperture Spherical radio Telescope(FAST)is very susceptive to radio frequency interference(RFI)from active radio services.Moreover,due to the rapid development of space applications and research,satellite interference has become one of the main RFI sources for FAST,particularly at the L band.Therefore,we have developed several measures to mitigate satellite RFI.On the one hand,an antenna with 4.5-meter diameter has been constructed and installed at the FAST site to detect the satellite interference in the frequency band between 1 to 5 GHz.Meanwhile,we have developed a satellite RFI database based on the FAST sky coverage,the observing frequency bands,and known satellite systems.By combining the satellite RFI monitoring antenna and the database,we have established a satellite RFI mitigation system.With this system,we can not only track satellites to collect their characteristics and update the database but also help the observer to program the observing plan by predicting satellite interference.During the practical observation of FAST at the L band,the feasibility of this system to mitigate satellite RFI has been proved.In particular,the system effectively avoids strong satellite interference from entering the main beam of the telescope and causing receiver saturation.