民勤绿洲边缘阻沙带表层土壤粒度空间分布特征

土壤粒度是风沙活动的重要表征参数。通过野外调查与室内测试,分析了不同空间分布防风固沙林表层土壤粒度的空间分布特征,旨在评价民勤绿洲边缘阻沙带防风固沙功能。结果表明:(1)坝区梭梭-沙拐枣-沙蒿-沙米固沙林表层土壤粒度组成以细砂、中砂、极细砂为主,分别占33.47%、26.08%、18.18%;泉山区白刺+沙蒿+五星蒿固沙林表层土壤粒度组成以细砂、粉粒和极细砂为主,分别占29.62%、21.17%、18.87%;湖区白刺-芦苇-猪毛菜固沙林表层土壤粒度组成以细砂、粉粒和极细砂为主,分别占36.66%、27.98%、22.83%。(2)平均粒径:坝区(2.55Φ)>泉山区(3.5Φ)>湖区(3.94Φ),分选性:坝区(1.58Φ)较差,湖区(2.10Φ)和泉山区(2.29Φ)很差。(3)泉山区、湖区表层土壤粒度频率曲线为双峰型,坝区为单峰型,偏度均为极正偏态,峰度表现为很窄。粒度累计分布曲线反映出坝区风沙活动较泉山区、湖区频繁、强烈。阻沙带荒漠植被群落物种组成决定着其防风固沙功能的大小,进而影响其表层土壤的粒度分布特征。建议阻沙带生态防护体系修复时应注重选择固沙能力强的造林树种。

刍议辽宁省边界阻沙带防护林建设工程

随着辽宁省计划投入1亿元苗木补助资金打造科尔沁沙地阻沙带防护林建设工程的实施,工程的建设、保障、保护和发展等就倍受关注。文章简要总结了相应的措施。

论华北平原的黄河古水系

为合理开发利用地下水及水资源调蓄 ,通过物探、钻探及室内分析数据 ,对华北平原埋深 2 0～ 35 m的数条 SW—NE向砂带进行了研究。该砂带具有许多河流相沉积标志 ,从分布格局、重矿物组合、砂带规模、古生物化石和1 4 C测年看 ,该带是末次盛冰期—早全新世形成的黄河古河道带。它切割了末次冰期间冰段棕红色粘土 ,形成了切割谷。谷内堆积了末次盛冰期—早全新世砂砾石 ,后又被中全新世淤泥质粘土掩埋而成为埋藏古河道带。它的存在说明黄河最晚在末次盛冰期就已经打开了三门峡 ,在渤海大陆架也留下了古河道带。

崇明岛形成的历史过程

本文根据2 0世纪80年代新发现的滨岸沙带,对唐武德年间成洲的东沙进行准确定位,然后以此为基础,论证崇明岛的基本框架和南、北支和南、北港分流,形成于元至元十四年稍前。明末清初之际,崇明岛完成大型沙洲合并过程,东西已达1 4 0余里,基本接近目前崇明岛长度。与此同时,支分已达40 0年的南北港,则因沙洲并岸而消失,南支江面随之展宽。1 3 5 2 -1 5 86年崇明城五次迁徙,是潮灾引起崇明岛冲淤变化的结果。在建的上海长江大桥陈家镇引桥,位处崇明岛最古老的东沙,基础坚实可靠,但冲淤变化永远不会停息,整个崇明岛均应密切注意潮灾的影响。

内蒙古地区风沙防护机理分析

研究目的:分析研究固沙带和阻沙带防风沙体系组成机理,分析工程防沙(机械)和植物防沙条件、防护宽度确定、植物选择依据和布置原则、养灌条件等,提出后期养护与维修工作及人员配置要求,提出新的风沙防护措施,分析植物风沙防护发展趋势。研究结论:(1)降雨量小于160 mm,地下水不能满足植物浇灌水量时采用工程防沙(机械防沙);降雨量160～280 mm,采用工程防沙+植物防沙相结合、微灌养灌;降雨量大于280 mm不需要微灌养灌、只需浇定根水。(2)植物防护采用乔灌木条带间隔布设,乔木株行距2 m×3 m、灌木采用2 m×1 m或2 m×1.5 m。(3)工程防沙:采用相应规格的方格和适应地形的数道高立式沙障相结合防护(树枝或土工网方格采用1 m×1 m;沙丘高度2～3 m,一般能远视,可以设1～2道高立式沙障,沙丘高度大于3 m,无法远视时设置2～3道高立式沙障)。(4)防护宽度:一条公路或铁路走向与风向夹角小于30°、防护宽度应按现行规范宽度L×sinβ(β为风向与线路的夹角)。(5)风沙防护新措施:地膜集水及有机植物加菌类孵化覆盖防沙。(6)植物防护风沙应与旅游、经济发展相结合,前期可适当增加投资。

冰岛—法罗海脊东南深海底形及底流特征

冰岛—法罗海脊位于东北大西洋和挪威海之间,其东南侧水深600～1 200m,构成法罗—设德兰水道(FSC)和法罗浅滩水道(FBC),两者相连合为挪威海深水通道(NS-DW)。持续而强劲的底层冷水流可搬运并沉积砂和砾级碎屑。利用侧扫声纳图、地震剖面和海底摄像识别出的大小沙波、新月形大沙丘、沙流、沙带、沙影和慧星痕等各种底形分布于顺水道5个区片中。一些大沙丘和沙带等大型底形形成于全新世大西洋期,如今基本稳定,偶尔活动,其他底形均处于运动之中。深海沉积底形结合水文实测资料揭示NS-DW水道自(61°N,5°W)向南再向西流,至第3出水口(冰岛盆地),全长约850km,宽约10～30km或更宽,冷水底层厚100～200m,流速0.3～1.0m/s或更高。在更向南的区域,逐渐混合于东北大西洋。

Formation, distribution, and nature of Picea mongolica in China

Picea mongolica is an endemic and endangered species in China. Ecosystem made of Picea mongolica is a special sandy forest ecosystem in China. It is found at ecotone between forest and steppe, or agricultural district and pastoral area. Based on investigation, this paper discussed the formation and distribution of Picea mongolica and studied its nature according to ecotone theory. It is clarified that Picea mongolica belongs to Picea meyeri series. That is to say, it became a local race through long-term adaptation to the local climate, then formed allopatric semi-species, and finally turned into a taxonomical species. Picea mongolica forest is a super zonal climax community developing in ecotone between forest zone and steppe zone.

辽蒙边界阻沙林带在防沙治沙的作用浅析

辽宁省现有沙化、荒漠化土地面积为68.72万hm^2。全部分布在朝阳、建平、北票、凌源、喀左、龙城等七县、市(区)的99个乡镇,其中北票、建平、朝阳县为重中之重。

辽蒙边界阻沙林带防沙治沙的作用浅析

辽宁省现有沙化、荒漠化土地面积为68.72万hm2。全部分布在朝阳、建平、北票、凌源、喀左、龙城等7县、市(区)的99个乡镇,其中北票、建平、朝阳县为重中之重。

Vegetation landscape structure and dynamics in sandy forest-steppe ecotone

Sandy forest-steppe ecotone in Baiyinaobao Natural Reserve of Inner Mongolia Autonomous Region of China is one of the special landscape types in forest-steppe vegetation zone in China. Vegetation landscape types, landscape patches, and patch size were measured by the field investigation, forest photograph, and airscape. The structure of landscape patches in sandy forest-steppe ecotone, including composition structure, and size structure, was studied and the dynamics and transformation of landscape patches were analyzed. The data obtained in this study could provide theoretical basis for the research on vegetation landscape in forest-steppe ecotones and other vegetation types.

Comparing the model forms estimating generalised diameter-height re-lationships in Tecomella undulata plantations in hot arid region of India

Four generalised diameter-height equations were developed and compared for pure and even-aged stands of Tecomella undulata in hot arid region of Rajasthan State in India. The data used to fit the equations consisted of 1 540 diameter-height observations collected from the plots laid out in uniformly stocked stands of varying age and density. The performance of four equations was tested by non-linear least squares regression and evaluated using different statistical criteria. Finally, these equations, with the same values of coefficients ob- tained during the fitting phase, were validated by an independent data set consisting of 854 diameter-height observations. Overall, equation （4） （Hui and Gadow function） was found to perform best for both the fitting data set as well as validation data set.

Meiofauna Distribution in Intertidal Sandy Beaches Along China Shoreline(18?–40?N)

In this study,the distribution pattern of meiofauna from nine sandy beaches at six latitudinal gradients along Chinese coast between 18 and 40?N was studied on their meiofauna abundance to examine the effect of latitudinal gradients.In general,meiofauna abundance was lower in four subtropical beaches in Xiamen(24?N) and Zhoushan(29?N) than that in other beaches.Meiofauna abundance differed little between tropical and temperate beaches.The taxonomic structure of meiofauna showed a dominance of nematode in colder area.The relative composition of turbellarians and polychaetes increased in warmer area.In addition to latitudinal gradient,salinity,oxygenation,sediment grain size affect also the meiofauna latitudinal distribution.As for horizontal distribution,the highest meiofauna abundance was found in low tidal zone at tropical beaches,and in middle tidal zone at temperate beaches.The horizontal distribution of meiofauna was controlled by both physical and biotic factors including feeding and anthropogenic activities.Although meiofauna abundance exhibited a horizontal difference,the composition of meiofaunal main taxa was unanimous horizontally at all beaches at the same sampling latitude.

^(210)Pb Chronology and Trace Metal Geochemistry in the Intertidal Sediment of Qinjiang River Estuary, China

Historical records of metal inputs were studied by using a sediment core collected from a sand-rich mudflat in the Qinjiang River estuary, China. 210Pb chronology was used to reconstruct the fluxes of Hg, Cu, Pb, Zn, Cd, Cr and As to the core site during the last 86 years. Based on the constant initial concentration model, the sedimentation rates are 1.18 cm year-1 in the top 30 cm sandy layer and 0.92 cm year-1 in the muddy bottom layer. To compensate for grain-size and mineralogy effects on metal concentra-tions, aluminum was used as the normalizing element. The enrichment factors (EF) indicate that the natural inputs had prevailed up to the early 1980s. After this period, the intensity of human activities has resulted in continual increasing trend of metals towards the surface. Recent sediment samples from the Qinjiang River estuary are found moderately enriched by Cd (EF>1.5) and slightly enriched by other metals (EF<1.5). Considering that the drainage area of the Qinjiang River is mostly agricultural land, the increased Cd may be due to the usage of fertilizers and pesticides in agricultural activities and the combustion of fossil fuels.

Characteristics of Suspended Particulate Matter and the Coastal Turbidity Maximum Areas of the Mekong River

This paper presents the results of application of a 3D （three-dimensional） numerical model to study on MTZ （maximum turbidity zone） in the coastal zone of Mekong River Delta. In this study, a 3D system model with combination of hydrodynamics--wave and suspended sediment transport was set up and validated with measured data in the study area. Based on calculated scenarios for the flood and the dry season, the results have shown appearance of MTZs in the coastal zone of Mekong River with suspended sediment concentration prevalent of 0.04-0.07 kg·m^3 （the dry season） and 0.05-0.1kg·m^3 （the flood season）. The position and MTZs scale change with the interaction between fresh water and tidal oscillations. The MTZ occur more in the dry seasons compared to the wet season. The MTZs are prevalent located far away from estuaries about in 12-22 km （in the dry season）, and 5-15 km in the flood season.

Response of Vegetation Cover to Climate Change and Influence of Dusty Weather in the Desertloess Transitional Zone of China

[Objective]This study aimed to analyze the relationships of the normalized difference vegetation index(NDVI)(1981-2006)in the desert-loess transitional zone of China with precipitation and temperature.[Method]The average method and the correlation function were applied in this study.[Result]The results indicated that during the growing season NDVI was positively correlated with precipitation in the current month,last month and the month before last,especially the last month.NDVI mostly negatively correlated with temperature,especially the temperature in the last month,which shows that the higher temperature,the more adverse the conditions for vegetation growth.[Conclusion]NDVI from August to October clearly is one of the significant factors influencing dust storm weather in spring of the next year.

Petrological characteristics,geochemical feature and metallogenetic relation of alkaline-rich rocks in northwest of Yunan Province,China

The alkali-rich rocks, spreading along the suture zone of Jingsha River, refer to the alkali-rich porphyry rocks, which emplace during the Himalaya epoch in northwest of Yunnan Province, and consist of syenit, syenit porphyry, monzonite porphyry and granite porphyry. Petrological chemical analysis results suggest that silica is poor and aluminum is rich, and high potassium large ion lithophile elements （LILE）, light rare earth element （LREE） and Sr are obviously detracted in these rocks. High field strength elements （HFSE） and heavy rare earth element （HREE） are depleted, especially Nb, Ta, P and Ti. 8Eu： 0.09--1.64 shows that plagioclase does not appear fractional crystallization during the formation of alkali-rich rocks, t^348, H and O isotopes and Pb isotopes suggest that ore-forming fluid is derived from the mantle, and Pb is possibly mixed by mantle, wall rock and crust. The age of Pb in alkali-rich rocks is about 250-220 Ma. The age of alkali porphyry rock （dykes） varies from 30 Ma to 50 Ma. Alkali rocks have strong metallogenetic relation. Au mineralization is associated to the alkali magrnatic activities with a relatively high temperature, low pressure and high oxygen fugacity. However, copper mineralization is mainly associated with alkali-sub-alkali magmatic activities in a process of relatively low temperature, high pressure and lower oxygen fugacity.

Simulation of the Strip-Flash Ethanol Continuous Fermentation Process

The conventional ethanol fermentaion is a typical inhibitory process, leading to low productivity and yield. A new ethanol fermentation process coupled with gas stripping and vacuum fash, named as strip-flash fermentation, is proposed. The process is provided with the advantages of both stripping fermentation and flash fermentation, and improves the ethanol productivity by increasing the in-situ ethanol removal. And a model of flash-strip fermentation process was established, the results from the model were consistent with the experiment values. The theoretically analyses indicate that increasing gas flux and liquid phase recycling ratio can help to enhance productivity and yield of strip-flash fermentation process, and comparison to striping fermentation or flash fermentation, flash-strip fermentation has shown a better productivity. The results has also shown the possibilities of further application and optimization of this process.

Study of the engineering geologic feature of weathering zone of bedrock in 810 producing area of Luling Mine

For a safe extracting of the mine resource of the razor thin capping rock, a study of waterproof, sand prevention, roof fall prevention must be made. As a result, it’s necessary to master the engineering feature of weathering zone of bedrock. According to the lithology appraisal and X diffract analyses, the mineral feature of weathering zone of bedrock in 810 producing area has been studied in this article. By testing the physical mechanics index of weathering zone, we have found out some features of physical mechanic quality. Utilizing the determined result of viscosity index and slaking test, we reach a conclusion of the water stability of weathering zone, that is the weathering zone rock belongs to the type that is easily slaked when encountered water and the water stability is weak.

The Effects of Protruding Rock Boulders in Regulating Sediment Intrusion within the Hyporheic Zone of Mountain Streams

Excessive sedimentation in mountain stream ecosystems is a critical environmental problem due to the clogging of streambeds by sediment particles within the hyporheic zone,with detrimental effects on fish spawning habitat.In this research,the effects of an array of boulders in regulating the intrusion of incoming sand within a gravel substrate were evaluated by performing detailed experiments in a laboratory flume.A unique experimental setup and two different sampling techniques were utilized for measuring the infiltrated sand within the gravel bed under two bed shear stress conditions(moderate vs.high).For comparison purposes,experiments were performed without and with the presence of partially submerged to the flow(protruding) boulders,which is typical for the average flow conditions found in mountain streams.Results indicated that sand infiltrated primarily in the upper part of the gravel bed creating a surface seal which hindered the penetration of sand particles deeper into the bed.An exponential decrease of the amount of the infiltrated sand within the hyporheic zone was observed in all experiments regardless of the presence of boulders.However,the presence of boulders promoted sediment intrusion of sand particles especially for the moderate applied bed shear stress condition,since the total amount of the infiltrated sand was found to be on average 44% greater whenboulders were present.The findings from this study can provide additional insight regarding the role of boulders on promoting downwelling of flow and sediment within the gravel substrate with potential effects on fish habitat.

浑善达克沙地公路机械沙障防风固沙效益分析

以穿越浑善达克沙地省际通道两侧公路防护带为试验区,以黄柳(Salix gordejevii Y.L.Chang et Skv.)和小红柳(Salix microstachya Turcz.)为主要材料设置的高立式柳条沙障阻沙带和半隐蔽式方格沙障固沙带构成的公路沙障带的防风固沙效益为研究对象,通过对公路两侧不同沙害发生地段的沙障带内风速、输沙量测定,分析风速变化、防风效益和地表粗糙度以及风沙流结构。结果表明:在平缓流沙地、风蚀窝状沙坑、挖方段沙质陡坡等主要公路沙害地段,风速在沙障带带内及其上空,都表现出较强的线形规律,其中沙障带在平缓流沙地风速变化线形规律最强,风速在50m宽的阻沙带中心及固沙带内显著降低,粗糙度渐增,防风效能提高。高立式柳条沙障阻沙带阻聚外源流沙主要发生于阻沙带前锋26m宽范围内,防护带其余近公路54m宽流沙地得到有效控制,表面保持稳定。