Spatial-temporal characteristics in landscape evolution of the Yellow River Delta during 1855- 2000 and a way out for the Yellow River estuary

Based on graphical and quantitative methodology of landscape ecology and Geo-information Tupu, this paper studies the landscape spatial-temporal evolution characteristics of the Yellow River Delta （YRD）, which was built up by periodic physical swings of the Yellow River （YR） rump channel during 1855-2000. According to the research on spatial-temporal evolution of YRD and YR rump channel, we conclude that the Qingshuigou channel has reached its limit and a new flow channel for YR should be built up sooner or later. It suggests that the shift of YR channel should abide by its natural rules of flowing through depressions among previous channels and could be carried out by artifical efforts. The paper discusses the problems and alternate ways out for treatment of the high content of silt in the YR flow at the estuary.     

Rapid shifts of the river plume pathway off the Huanghe （Yellow） River mouth in response to water-sediment regulation scheme in 2005

The Huanghe River (Yellow River), historically being considered as the second largest world river in terms of sediment load to the sea (approximately 10.8×108 t/a)[1], has experienced drastic declines in its water and sediment fluxes to the coastal ocean over the past 50 years[2,3]1). A series of consequences of decreasing water and sediment discharge emerged including frequent flow cutoff, lifting of riverbed elevation and lower capability of flood con- trolling. In July 2002 the Yellow Ri…     

Distribution and partition of polybrominated diphenyl ethers （PBDEs） in water of the Zhujiang River Estuary

The spatial, temporal, and vertical distributions of polybrominated diphenyl ethers （PBDEs） in water columns from the Zhujiang River Estuary were examined, and the partition behavior of PBDEs between particle and dissolved phases was investigated in the present study. The results show that the distributions of PBDEs concentrations in the water varied with the sampling seasons. The PBDEs concentrations in water samples were lower in May 2005, when the brackish water was dominant in the estuary, than in October 2005, when fresh water from river runoff dominated the estuary. The spatial distribution of PBDEs in October 2005 indicated that the river runoff was the major mode to input PBDEs to the estuary, and the concentration of PBDEs in water might be dissolved organic carbon （DOC） dependence. The spatial and vertical distributions of PBDEs in May 2005 were relatively homogeneous, and SPM was the major factor on controlling the levels of PBDEs in this sampling time. Both DOC and POC could play certain roles in determining the distribution and partition of PBDEs between particle and dissolved phases, but their effects varied with the water properties.     

Discovery of Late Carboniferous strata and their tectonic significance in the southern margin of the North China Block （Huoqiu and Gushi areas）

Late Carboniferous fossils （such as Boultonia？ sp., Tabulata, and spiriferoid specimens with smooth she/Is）, bioclastic material （such as crinoid stems and sponge fragments）, and Late Ordovician microfossils of the conodont Belodina have been discovered in the lower part of the strata typically referred to as the Neoproterozoic on the boundary of the provinces of Anhui and Henan in the southern margin of the North China Block. These findings prove that the strata contain macrofossils belonging to the Late Carboniferous, which belonged to a carbonate debris flow deposit that was formed under a carbonate slope environment. The conodont fossils might belong to a detrital deposit. Thus, it is possible to reset the stratigraphic sequences and tectonic attributes belonging to the North Huaiyang tectonic belt and limit the Shouxian fault to the boundary between the Dabie Orogen and North China Block.     

Does chemical index of alteration （CIA） reflect silicate weathering and monsoonal climate in the Changjiang River basin？

Chemical weathering of continental silicates significantly influences global climate change,earth surface processes,material cy-cling and oceanic chemical composition.How to quantitatively reconstruct chemical weathering history has become an important issue in global change research.Chemical index of alteration(CIA) has been widely used as a quantitative indicator for estimating the degree of silicate weathering.However,its method of calculation and the limitations of its application are not well understood.In this study,we calculated CIA values from suspended particulate matter collected from the mainstream and major tributaries of the Changjiang River.The values yielded considerable variations at different temporal and spatial scales.The average CIA values increased from the upper to middle-lower reaches,and were lower in the suspended samples taken during the flood than in the dry season.The spatial variation in the CIA is predominantly controlled by basinal monsoon climate.In contrast,the temporal varia-tion in the Changjiang River basin is controlled mainly by the changing provenance of suspended samples in relation to the shift of the precipitation zone.The CIA probably indicates the integrated weathering history in the river basin,and thus,cannot be used as a reliable proxy of instantaneous chemical weathering.Furthermore,the calculation method and hydrodynamic sorting also influence the CIA values.Therefore,caution should be taken when using the CIA as a proxy for studying chemical weathering from different regions.     

Inclusion of the Eastern Asia endemic genus Sorolepidium in Polystichum （Dryopteridaceae）： Evidence from the chloroplast rbcL gene and morphological characteristics

The taxonomic status of the Eastern Asia endemic Sorolepidium is controversial. Some authors accept it as member of the large diverse genus Polystichum, whereas others suggest that it is an independent genus separated from the later by the exindusiate sorus and the absence of aristate teeth at the pinnae margins. Here we infer phylogenetic relationship of Sorolepidium using DNA sequences of the chloro-plast rbcL gene. Phylogenies were inferred using maximum-parsimony, maximum-likelihood, and Bayesian inference methods. Molecular data establish that Sorolepidium is deeply nested within the large genus Polystichum and has a close relationship with P. duthiei and P. lachenense in the model-based analyses. The Kimura 2-parameter distances of the rbcL sequences between S. glaciale and P. duthiei and P. lachenense were 0.1 and 0.2%, respectively. Furthermore, S. glaciale differed from P. duthiei by a single nucleotide in their rbcL sequences. Close relationships between S. glaciale and P. duthiei and P. lachenense are also supported by the shared spore ornamentation with echinate fenes-trate folds.     

Thawing and freezing processes of active layer in Wudaoliang region of Tibetan Plateau

The interaction between permafrost and atmosphere is accomplished through transfer of heat and moisture in the overlay active layer. Thus, the research on the thermal and hydrodynamics of active layer during the thawing and freezing processes was considered a key to revealing the heat and moisture exchanges between permafrost and atmosphere. The monitoring and research on active layer were conducted because permafrost occupies about two thirds of the total area of the Tibetan Plateau. Based on the analysis of the ground temperature data and soil moisture data of monitoring near the Wudaoliang region of the Tibetan Plateau, the thawing and freezing processes of active layer were divided into four stages, i.e. summer thawing stage (ST), autumn freezing stage (AF), winter cooling stage (WC) and spring warming stage (SW). Coupled heat and water flow is much more complicated in ST and AF, and more amount of water is migrating in these two stages. Heat is transferred mainly via conductive heat flow in the other two stages, and less water migrated. Four water migration and coupled heat flow processes were addressed for the thawing and freezing stages, which are water infiltration driven by gravity, moisture advection and distillation driven by temperature and osmotic gradients, water migration driven by capillarity and unfrozen water migration driven by temperature gradient. The water content near the permafrost table tends to increase after one thawing and freezing cycle, which is the main reason for the development of thick ground ice layer near permafrost table.     

黄河流域布病时空分布特征及影响因素研究

布病在我国起源于20世纪50年代,是一种以牛羊为主要传染源的人畜共患类传染病.由于黄河流域历来是农牧业重要的支撑带,因而研究农牧业较为发达的黄河流域布病的时空分布规律具有代表性.以黄河流域覆盖到的9个省为研究区,借助SPSS的统计分析和ArcGIS的制图输出功能,研究布病发病的时空分布规律,同时从社会经济、环境及气象3个方面选取11种指标探讨其与布病发病人数的相关性.结果表明:在空间上,布病发病人数呈现从北到南逐渐减少的趋势;在时间上,20世纪50-70年代为布病初始爆发期,80-90年代中期呈低水平平稳波动且布病得到有效控制,1994年后再次出现爆发性增长,到2015年发病总人数达到历年最高;从影响因素看,第一、第二和第三产业产值以及废水排放、常住人口和城镇化率6类要素与布病发病的相关性最为密切,在多数省份都通过了P<0.01的显著性检验;废水排放量与黄河流域布病发病人数的相关性超过了0.9(P<0.01),预示着未来应加强对水污染的治理.此外,气温在宁夏、甘肃、山西、陕西及内蒙古5地与布病发病人数表现出显著正相关(P<0.01),体现出气候变暖对布病发病的影响.     

饱和砂层渗流冻结水热耦合模型与试验验证

为研究渗流作用下饱和砂层冻结规律,根据冻结过程中土体水分迁移及热量变化、热力学和渗流力学的基本理论,并考虑冻结过程中绝对孔隙率的降低对渗流的影响,基于Harlan水热耦合模型,建立了饱和砂层含相变全参数渗流冻结耦合数学模型,并应用COMSOL有限元软件与MATLAB编程,实现了耦合数学模型的数值求解。设计了相似模型试验验证了该模型及方法的合理性。研究结果表明:数值模拟结果与试验结果较为吻合,数学模型与求解方法合理、有效,为今后渗流地层冻结的拓展研究提供可靠数学与试验基础。     

黄河三角洲湿地植物根区优先流区和基质流区土壤特性分布差异

以黄河三角洲国家级自然保护区典型湿地植物盐地碱蓬根区土壤为研究对象,结合野外染色示踪实验和室内土壤性质测量实验,分析优先流区和基质流区土壤特性的分布差异,加深对湿地生态系统优先流对土壤影响的理解,对恢复湿地植被具有指导意义．结果表明:1）土壤有机碳、有机质、全氮和有效磷质量分数随着土壤深度的增加逐渐减小,土壤水质量分数随着土壤深度的增加先减小后增加,土壤全磷质量分数随土壤深度变化幅度较小．2）优先流区土壤有机碳、有机质、全氮和有效磷质量分数显著高于基质流区,两区土壤全磷质量分数不存在显著性差异．土壤深度为0~20 cm,优先流区土壤水质量分数高于基质流区;土壤深度>20~60 cm,基质流区土壤水质量分数高于优先流区,但差异均不显著．3）优先流区土壤有机碳、有机质、全氮和有效磷呈显著正相关,基质流区土壤有机碳、有机质和有效磷呈显著正相关．      

黄河源区气候特征及其变化分析

利用黄河源区近40年的温度、降水资料,分析了黄河源区气温与降水的时空分布特征和变化趋势。结果表明：黄河源区东北部的兴海、同德和东南部的久治县热量条件相对较好,由东向西随着纬度、尤其是随海拔的升高年平均气温逐渐下降;黄河源区年平均气温的差异很大,最暖的兴海县比最寒冷的称多县年平均气温高出6．2℃;降水年内分配集中在5～9月份,降水量占年总量的85．4％;近40年来年降水量无明显的变化趋势,但冬、春季的降水量呈明显的增多,而夏、秋季降水量呈明显的减少;气温呈明显的升高趋势,20世纪90年代比60年代年平均气温偏高0．5℃,≥0℃积温比60年代增加60～70℃,80年代以来增温主要出现在冬季和秋季。     

矿业密集区地表热环境时空演变特征及驱动力分析

矿产资源是人类赖以生存的重要物质基础,矿业开采在促进地方经济、文化等快速发展的同时,会对区域地表热环境造成一定影响。在遥感和地理信息系统(geographic information system, GIS)技术的支持下,准确和快速地获取地表温度(land surface temperature, LST)及矿业用地信息,结合迁安市矿业开发过程特点,借助“黄蓝—差值影像法”、叠加分析法和剖面分析法等方法,系统分析了2000—2018年间,迁安市矿业密集区马兰庄镇的地表热环境时空演变特征及驱动力。结果表明：贯穿典型矿业用地的4条温度剖面线的波谷(低温区)均位于绿地和水域,波峰(高温区)均位于矿区采场裸岩、未进行生态修复的排土场矿渣和尾矿库内尾砂。2000—2018年马兰庄镇的高温区面积占比从2000年的25.11%,上升到2008年的39.93%,再下降到2018年的28.71%;矿业用地占比从2000年的25.78%,上升到2008年的38.78%,再下降到2018年的27.94%;矿业用地和高温区变化趋势基本一致,并且矿业用地与高温区空间位置基本重合。研究结果将深化矿业密集区地表热环...     

黄河源区湿地及邻近草甸土壤糖类含量比较

通过分析黄河源区湿地及其邻近草甸土壤糖类含量差异用于评价源区湿地的健康状态。试验采用苯酚—硫酸法测定了黄河源区不同湿地和邻近草甸0~20 cm土壤的单糖含量和0~30 cm土壤的多糖含量。结果表明:湿地土壤0~20 cm的单糖含量为20.01~133.52 mg/kg;邻近草甸土壤0~20 cm的单糖含量为35.53~120.81 mg/kg。湿地土壤0~30 cm的多糖含量为78.01~805.21 mg/kg;邻近草甸土壤0~30 cm的多糖含量为109.93~553.89 mg/kg。不同类型湿地及其邻近湿地土壤单糖含量均随土壤深度的增加而减少,而湿地和草甸同一层的差异随湿地类型而异。河流湿地和沼泽湿地土壤多糖含量高于邻近草甸的,但湖泊湿地中邻近草甸多糖含量均高于湿地土壤含量。     

黄河水沙过程调控与下游河道中水河槽塑造

笔者以维持黄河健康为目标,以改善黄河不协调的水沙关系为切入点,采用现场调研、实测资料分析、理论分析和水沙数学模型计算等技术手段,对黄河水沙过程变异与洪水过程的作用、黄河下游断面形态与洪水过程的响应关系、下游水沙过程调控对塑造与维持下游中水河槽的作用、塑造与维持中水河槽的影响因素等进行了系统研究,提出了塑造与维持黄河下游4000m^3／s左右中水河槽的方案,为黄河下游河道的治理提供了科学依据．     

TBM掘进机在引黄工程中的应用

由于采用了先进的TBM掘进机进行施工，万家寨引黄一期工程实现了长距离、大埋深引水隧洞的快速施工。文章介绍了TBM的技术特点、使用情况以及施工中存在问题和处理措施。