A case study of long-term field performance of check-dams in mitigation of soil erosion in Jiangjia stream,China

This paper examines the long-term field performance of the check-dams in mitigation of soil erosion in the Duozhao catchment of Jiangjia stream, southwest China. Since their construction between 1979 and 1982, the check-dams have been functioning effectively. The examination is made via comparisons between the environmental conditions of the Duozhao catchment with its adjacent Menqian catchment in the stream, because no check dams were constructed in the Menqian catchment. The examination is based on recent field investigations and aerial photograph analyses, and covers four aspects: (a) bed gradients of catchment channels; (b) stability of bank slopes; (c) rates of land erosion; and (d) vegetations on bank slopes. The field data demonstrate that the check-dams have had the following good functions for mitigation of soil erosion: (1) restricting the channel depth and lateral erosions, (2) protecting the channel erosion base, (3) reducing the bed gradients of debris-flow channels, (4) fixing the channel bed, (5) stabilizing the bank slopes, as well as (6) facilitating the growth of vegetations. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Temporal and spatial characteristics of surface water quality by an improved universal pollution index in red soil hilly region of South China: a case study in Liuyanghe River watershed

Selecting the Liuyanghe River watershed as an example, using monitoring data of water quality of nearly 10 years and the improved synthesis pollution index method to evaluate the water quality, the research studied the temporal and spatial characteristics of surface water quality of a typical basin in the red soil hilly region, and analyzed reasons for the surface water quality change. The results indicated the improved synthesis pollution index had a better serviceability than other methods, such as, Pollution Index method, Fuzzy Evaluation method, Grey-System method etc. As for the temporal characteristic, because of no-point source pollution, the water quality of Liuyanghe River watershed had become a more and more serious problem over a ten-year period. The spatial characteristic indicated that the pollution degree increased from upstream to downriver. Water quality upstream was better, and the content of the heavy metals was higher in the middle of the river, and the pollution of ammonia nitrogen intensified downriver. The result suggested the improved universal pollution index could be used in the assessment of the water environment.     

Geology and Lead-Isotope Study of the Baiyinnuoer Zn-Pb-Ag Deposit, South Segment of the Da Hinggan Mountains, Northeastern China

The Baiyinnuoer deposit (32.74 Mt ore with grades of 5.44% Zn, 2.02% Pb and 31.36 g t^?1 Ag), the largest Zn‐Pb‐Ag deposit in northern China, is hosted by crystalline limestone and slate of the Early Permian Huanggangliang Formation. Detailed cross‐section mapping indicates stratigraphic and fold structural controls on the mineralization. The Zn‐Pb‐Ag mineralization is hosted predominantly by skarn, which occurs as bedding‐parallel lens that pinch out at the margins of the main economic zone. Three skarn stages are identified at the deposit: (i) garnet‐clinopyroxene; (ii) sulfides; and (iii) carbonate‐epidote. Lead isotopic compositions were determined for galena and sphalerite of the ores, whole rock samples of the Yanshanian granite and granodiorite, Permian marble and tuff, and Jurassic volcanic and subvolcanic rocks in and around the Baiyinnuoer area in order to discuss the sources of ore‐forming materials and the relationship between the ore formation and these whole rocks. Galena and sphalerite of the Baiyinnuoer ore have uniform isotopic ratios (²⁰⁶Pb/²⁰⁴Pb, 18.267–18.369; ²⁰⁷Pb/²⁰⁴Pb, 15.506–15.624; ²⁰⁸Pb/²⁰⁴Pb, 38.078–38.394) consistent with the granite and granodiorite (²⁰⁶Pb/²⁰⁴Pb, 18.252–18.346; ²⁰⁷Pb/²⁰⁴Pb, 15.504–15.560; ²⁰⁸Pb/²⁰⁴Pb, 38.141–38.320), whereas the ratios for Jurassic volcanic and subvolcanic rocks are variable and radiogenic (²⁰⁶Pb/²⁰⁴Pb, 18.468–18.614; ²⁰⁷Pb/²⁰⁴Pb, 15.521–15.557; ²⁰⁸Pb/²⁰⁴Pb, 38.304–38.375). These results indicate that the mineralization was not related to the Jurassic volcanism, but to the Yanshanian magmatism. The Permian strata may have a slight contribution to the mineralization. All features show that the Baiyinnuoer deposit is related to the Yanshanian granitic magmatism, and can be classified as a zinc‐lead‐silver skarn deposit.     

西藏仁布地区上三叠统重矿物组合与物源分析

采用重矿物组合和指数方法对西藏南部仁布地区上三叠统朗杰学群和涅如组的物源进行了分析。结果显示：该区上三叠统常见的重矿物主要为锆石、磷灰石、金红石、锐钛矿和电气石;重矿物组合ZTR和ATi指数均高,MZi指数较低但多见,GZi指数低且多为零;郎杰学群的ZTR和ATi指数成反比关系,涅如组的ZTR增加时ATi基本不受影响。仁布地区上三叠统的物源主要来自火山岩,次为中酸性岩浆岩,少量来自变质岩和超基性侵入岩;涅如组的物源可能来自南边;朗杰学群的物源则可能来自北边,向郎杰学群提供物源的可能是拉萨地块。涅如组和郎杰学群在重矿物组合及其指数上的异同的成因有待进一步工作     

浙赣交界地区上奥陶统红家坞组(O3h)

红家坞组为 1/ 5万《球川镇幅》和《常山县幅》新建岩石地层单位。本组分布于浙皖盆地东南缘 ,系指江山、常山、玉山地区 (简称为“三山”地区 )出露的一套杂色砂岩—泥岩组合 ,层位与文昌组灰绿色砂岩、粉砂岩相当 ,在岩性、岩相上又与之有明显区别的海相红层 ,厚度 380— 4 83m ,典型剖面位于浙江省江山市大桥镇仕阳尾行政村红家坞村。该组的建立 ,丰富了浙赣“三山”地区岩石地层资料。     

Formation of Fe-oxyhydroxides from the East Pacific Rise near latitude 13°N: Evidence from mineralogical and geochemical data

The mineralogical and geochemical characteristics of Fe-oxyhydroxide samples from one dredge station (long. 103°54.48′W, lat. 12°42.30′N, water depth 2655 m) on the East Pacific Rise near lat 13°N were analyzed by XRD, ICP-AES, and ICP-MS. Most Fe-oxyhydroxides are amorphous, with a few sphalerite microlites. In comparison with Fe-oxyhydroxides from other fields, the variable ranges in the chemical composition of Fe-oxyhydroxide samples are very narrow; their Fe, Si, and Mn contents were 39.90%, 8.92%, and 1.59%, respectively; they have high Cu (0.88%–1.85%) and Co (65×10⁻⁶−704×10⁻⁶) contents, and contain Co+Cu+Zn+Ni> 1.01%. The trace-element (As, Co, Ni, Cu, Zn, Ba, Sr) and major-element (Fe, Ca, Al, Mg) contents of these samples are in the range of hydrothermal sulfide from the East Pacific Rise near 13°N, reflecting that this type of Fe-oxyhydroxide constitutes a secondary oxidation product of hydrothermal sulfide. The Fe-oxyhydroxide samples from one dredge station on the East Pacific Rise near 13°N are lower in ΣREE (5.44×10⁻⁶–17.01×10⁻⁶), with a distinct negative Ce anomaly (0.12–0.28). The Fe-oxyhydroxide samples have similar chondrite-normalized rare-earth-element (REE) patterns to that of seawater, and they are very different from the REE composition characteristics of hydrothermal plume particles and hydrothermal fluids, showing that the REEs of Fe-oxyhydroxide are a major constituent of seawater and that the Fe-oxyhydroxides can become a sink of REE from seawater. The quick settling of hydrothermal plume particles resulted in the lower REE content and higher Mn content of these Fe-oxyhydroxides, which are captured in part of the V and P from seawater by adsorption. The Fe-oxyhydroxides from one dredge station on the East Pacific Rise near 13°N were formed by secondary oxidation in a low temperature, oxygenated environment. In comparison with the elemental (Zn, Cd, Pb, Fe, Co, Cu) average content of hydrothermal sulfide samples from the East Pacific Rise near 13°N, the Zn, Cd, and Pb contents of the Fe-oxyhydroxides are lower, and their Fe, Co, and Cu contents are higher. Supported in part by the Pilot Project of Knowledge Innovation Project, Chinese Academy of Sciences (Grant No. KZCX3-SW-223), and the Special Foundation for the Tenth Five Plan of COMRA (Grant No. DY105-01-03-1)     

Bacterial community in deep subseafloor sediments from the western Pacific “warm pool”

The bacterial community in deep subseafloor sediments at a depth of 230 cm from the western Pacific “warm pool” is studied by construction of 16S rDNA clone library and PCR-RFLP (Restriction Fragment Length Polymorphism) analysis. The results indicate that the bacterial community in these sediments is mainly composed of five groups: α-Proteobacteria, β-Proteobacteria, CFB group (Cytophaga / Flexibacteria / Bacteroides), Acidobacteria and gram positive bacteria, with a few genera detected in each group. The most abundant bacteria group is α-Proteobacteria, and the next is β-Proteobacteria. The dominant species in α-and β-Proteobacteria are Sphingomonas paucimobilis and Pseudomonas alcaligenes respectively. The CFB group is simply composed of members belonging to Flavobacterium. The gram positive bacteria are rich, and mainly consists of the genus Geobacillus. The analysis of bacterial community indicates that organic matter is still abundant in the subseafloor sediments at the depth of 230 cm in the western Pacific “warm pool”. These bacteria in this deep biosphere may play an important role in the nitrogen cycle of deep sea sediments at “warm pool”. Supported by the National Key Basic Research Support Foundation of China (Grant No. G2000078500) and China Ocean Mineral Resources R&D Association Project (Grant No. DY105-4-2-4)     

Coupling relationships between brachiopods and Girvanella during the Late Devonian F-F transition in Guilin, South China

The abundance curves derived from area proportions of brachiopods and Girvanella in the thin sections from the Yangdi section, South China, exhibits complex relationships during the Late Devonian Frasnian-Famennian transition. The living activity of brachiopods such as grazing and borrowing did great damage to the growth of Girvanella. However, there was more to just a mere a survival competing relationship between them, Girvanella actually improved marine environments by oxygenating the dysoxic ambient sea-water through photosynthesis in the lower Kellwasser Horizon. Profited from this improvement brachiopods’ abundance increased subsequently and suppressed Girvanella again. Nonetheless, without Girvanella’s photosynthesis, brachiopods were wiped out by the farther anoxic environments in the upper Kellwasser Horizon. The complex relationships between Girvanella and brachiopods may be a key to unlocking the relationships between geomicrobes and metazoans in the geological overturn periods. Supported by NSFC Innovation Research Group Program (Grant No. 40621002), MOE Innovative Research Team Program (Grant No. IRT0546), the National Natural Science Foundation of China (Grant Nos. 40472020, 40730209, 40802005 and 40872001) and SINOPEC Project (Grant No. G0800-06-ZS-319)     

闽东南沿海老红砂的分布与沉积地貌特征

本文通过野外调查,阐明了老红砂的分布与地貌形态特征,并根据其沉积的构造特征等提出了老红砂的风成或风－坡积成因及其发育多期性的观点。最后还对进一步研究提出若干建议。     

岩溶矿井煤层底板突水系统的非线性特征初步分析

本文论述了矿井煤层底板突水是一种由缺陷诱导的局域失稳,特别强调存在两种时间尺度的缺陷变化过程。一种是缺陷发育过程,缺陷由小缓慢地扩张变大,是慢变化;另一种是缺陷失稳过程,缺陷的薄弱破坏引起缺陷的瀑涨,是快变化,这后一过程就是矿井煤层底板突水。据此构造了塞子模型并讨论了模型的基本行为,定量地给出失稳判据,用实例检验模型得到准确率为92. 6%。