Eutrophication investigation and assessment of the Daning River after water storage of the Three Gorges Reservoir

The Daning River is a very important tributary in the Three Gorges Reservoir area. It is also a famous scenic spot. Anomalies appeared after water storage of the reservoir in June, 2003. In September, 2003, eutrophication monitoring in the 135-m backwater reach of the Daning River was conducted and the data were simply analyzed. The assessment result is that water body in the segment from Shuauglong to Longmen was mesotrophic or eutrophic. At the same time, the causes of its nutritional change were discussed, and counter-measures have been proposed.     

An Analytic Model of Galactic Winds and Mass Outflows

Galactic winds and mass outflows are observed both in nearby starburst galaxies and in high-redshift star-forming galaxies. We develop a simple analytic model to understand the observed superwind phenomenon with a discussion of the model uncertainties. Our model is built upon the model of McKee & Ostriker for the interstellar medium. It allows one to predict how properties of a superwind, such as wind velocity and mass outflow rate, are related to properties of its starforming host galaxy, such as size, gas density and star formation rate. The model predicts a threshold of star formation rate density for the generation of observable galactic winds. Galaxies with more concentrated star formation activities produce superwinds with higher velocities. The predicted mass outflow rates are comparable to (or slightly larger than) the corresponding star formation rates. We apply our model to both local starburst galaxies and high-redshift Lyman break galaxies, and find its predictions to be in good agreement with current observations. Our model is simple and so can be easily incorporated into numerical simulations and semi-analytical models of galaxy formation.     

深谋远虑 统筹规划 推进产业体系构建和区域布局构架

省委十届二次全会结束后，省国土资源厅迅速对贯彻落实会议精神作出部署。9月10日，省国土资源厅召开党组（扩大）会12％，传达学习贯彻省委十届二次全会精神。厅机关处（室）和直属事业单位的6位负责人，结合本职业务，就如何服务加快新型工业化进程作了发言。本刊现将发言摘录如下，供广大读者学习借鉴。[编者按]     

^137Cs法测算黄土高原土壤侵蚀速率的初步研究

核尘埃~(137)Cs降落到地表后,被土壤胶粒强烈吸附,集中分布于0—25cm的土壤表层。土壤剖面的~(137)Cs总量随土壤的流失而减少。根据黄土农耕地和非农耕地土壤的~(137)Cs流失模式,推导了它们的流失量和侵蚀速率的相关公式。根据陕西洛川黑木沟和山西离石羊道沟的13个土壤剖面的~(137)Cs含量测试结果,求得的黑木沟草坡覆盖的老谷坡和新谷坡的侵蚀速率分别为1400 t/km~2·a和5700t/km~2·a;羊道沟梁峁坡农耕地的侵蚀速率为3270—6030 t/km~2·a;裸露新谷坡的侵蚀速率大于8000 t/km~2·a。     

前陆盆地砂岩中的重复性地层模式及其构造意义

通过比较各段中每个准层序的进积规模和各次层序海相上倾终端的位置，在犹他州上白垩统布莱克霍克组的段内建立了两种独特的重复出现的堆叠地层模式。在同一段内，不论层序界面是否分隔开准层序，最虫的准层序总是比较晚的准层序进积较远。其结果是在各段中，进积距离的样式导致了从先进积到后加积的地层堆叠模式。     

全球扰动场源的研究及其大地构造意义

作为大地重力学反问题研究的实际应用，本文计算了全球扰动场源．在参数选择、赋值模式上，首先考虑到地球的成层结构与密度异常分布．研究表明，地球内部物质分布的不均一性主要体现在岩石层块体内部，并一直延深到幔核边界；地壳中的构造活动与地球内部物质分布状态相关．从大地构造学的角度，分析对比讨论了扰动场源所揭示的地球深部地质作用机理．     

A regression model to estimate regional ground water recharge

A regional regression model was developed to estimate the spatial distribution of ground water recharge in subhumid regions. The regional regression recharge (RRR) model was based on a regression of basin-wide estimates of recharge from surface water drainage basins, precipitation, growing degree days (GDD), and average basin specific yield (SY). Decadal average recharge, precipitation, and GDD were used in the RRR model. The RRR estimates were derived from analysis of stream base flow using a computer program that was based on the Rorabaugh method. As expected, there was a strong correlation between recharge and precipitation. The model was applied to statewide data in Minnesota. Where precipitation was least in the western and northwestern parts of the state (50 to 65 cm/year), recharge computed by the RRR model also was lowest (0 to 5 cm/year). A strong correlation also exists between recharge and SY. SY was least in areas where glacial lake clay occurs, primarily in the northwest part of the state; recharge estimates in these areas were in the 0- to 5-cm/year range. In sand-plain areas where SY is greatest, recharge estimates were in the 15- to 29-cm/year range on the basis of the RRR model. Recharge estimates that were based on the RRR model compared favorably with estimates made on the basis of other methods. The RRR model can be applied in other subhumid regions where region wide data sets of precipitation, streamflow, GDD, and soils data are available.