Delaunay三角网增点生长构造法研究

论述了一种由计算机自动生成Delaunay三角网的增点生长构造法。该方法属于不规则三角网的动态构网法，它借鉴了静态构网法中递归生长算法的部分思想，并利用Lawson提出的最大最小(MAX—MIN)角度法则对三角网进行即时的局部优化，从而达到了快速、有效地构建Delaunay三角网的目的。该方法对快速生成海底DEM数据，进行海底仿真具有重要的作用。     

不同氮源对微小亚历山大藻生长和毒素产生的影响

通过尿素、氯化铵、酵母浸出粉和硝酸钠等氮源对微小亚历山大藻(Alexandrium minutum)生长及毒素产生的影响研究,分析了微小亚历山大藻对不同氮源利用状况的差异.结果表明,在氮饥饿条件下,加入硝酸钠和酵母浸出粉能显著促进微小亚历山大藻的生长;高浓度的氯化铵在加入后对微小亚历山大藻有一定的毒性效应,表现为生长停滞,但毒性效应在5 d后消失,并得到与添加硝酸钠及酵母浸出粉相似的增长速率0.21 d-1;添加尿素对微小亚历山大藻的生长没有显著促进作用.在四种氮源中,尿素对微小亚历山大藻毒素产生的刺激作用也最弱,在稳定期每个细胞藻细胞毒素含量维持在6.00~8.00 fmol;添加硝酸钠、氯化铵和酵母浸出粉的藻细胞在稳定期毒素含量分别达到11.85,12.86和14.64 fmol.硝酸钠和氯化铵刺激藻毒素产生的效果比酵母浸出粉更为直接.四种含氮营养盐对微小亚历山大藻毒素组成的影响都很小.     

认清形势明确任务切实抓好今年的地质灾害防治工作——在全省地质灾害防治工作会议上的讲话

4月下旬,随着我省梅雨、台风季节即将来,临,省厅防患于未然,及时组织召开全省地质灾害防治工作会议,部署地质灾害防治工作此次“5.12”汶川大地震,在抗击自然灾害方面向人类敲响了警钟。本刊特编辑这组稿件,以强化地质灾害防治意识和预防措施．     

The concentration and distribution of different mercury species in the water columns and sediment of Aha Lake

In order to find out whether Aha Lake was polluted by the acid mining waste water or not, the concentration and distribution of different mercuryspecies in the water columns and sediment profile collected from Aha Lake were investigated. It was found that discernible seasonal variation of different mercury species in water body were obtained in the Aha Reservoir. With regards to the whole sampling periods, the concentrations of HgP in the Aha Reservoir water body were evidently correlated to the concentrations of total mercury, showing that total mercury was mostly associated with particle mercury. The concentrations of methylmercury in water body were also evidently correlated to the concentrations of dissolved mercury. The dissolved mercury evidently affects the distribution and transportation of methylmercury. However, there is no correlation between methylmercury and total mercury. The dissolved mercury, reactive mercury, dissolved methylmercury levels in the water body of high flow period were much higher than those in low flow period. The distribution, speciation and levels of mercury within the Aha Reservoir water body were governed by several factors, such as the output of river, the release of sediment . Discernible seasonal variation of total mercury and methylmercury in porewater was described during the sampling periods, with the concentrations in high flow period generally higher than those in low flow period. The methylmercury in pore water column was evidently correlated to that of the sediment. The results indicated that highly elevated MeHgD concentrations in the porewater were produced at the depths from 2 to 5 cm in the sediment profile, and decreased sharply with depth. A positive correlation has been found between MeHgD formation and sulfate reducing bacterial activity. These highly elevated concentrations of MeHgD at the intersurface between waters and sediments suggest a favorable methylation condition. Moreover,     

Response of Ruppia maritima to the reclaimed wastewater in coastal artificial landscape river

In recent years, reclaimed wastewater as a water source for urban artificial landscape rivers is being rapidly developed in some coastal cities with limited water resource available in China. However, eutrophication occurs more often in the landscape waterbody with reclaimed wastewater than in natural rivers and lakes. The study of restoration and reconstruction of macrophytes, especially the submerged aquatic vegetation, is essential to inhibit eutrophication of reclaimed wastewater. This study investigated the seasonal variation of biomass of Ruppia maritima in the artificial landscape river using reclaimed wastewater as the only water source in Tianjin, China. It was found that there were two seasonal growth peaks of Ruppia maritima each year in the coastal reclaimedwastewater. The contents of nitrogen and phosphorus of Ruppia maritima varied with the season.     

封面图片说明：邦达草原

邦达草原位于青藏高原东部西藏昌都地区，是横断山区北部他念他翁山高山深谷中一块地势宽缓、水草丰美的高寒草原。其东面为澜沧江，西侧是怒江，平均海拔约4000m；怒江支流玉曲上游由北向南蜿蜒流淌其中，两岸广阔的低湿滩地牧草生长茂盛。邦达草原也是许多重要药用植物的主要产区，诸如冬虫夏草、贝母、人参果、大黄、大叶秦艽和红景天等。每年6～8月草原绿茵如毡，开满了五颜六色的小花，成群的牛羊悠闲地觅食，碧蓝的天空白云飘动，无垠的高原宛如一幅秀美的风光画卷!全世界最高的机场——邦达机场（海拔4300多m）就坐落在草原上。     

我国高寒草甸植被生产力及其影响因子

生物量是重要的植物群落数量特征，直接反映生态系统生产者的物质生产量，是生态系统生产力的重要体现。高寒草甸广泛分布于青藏高原，是高寒生态系统的主要植被类型。回顾了高寒草甸生物量的研究成果。高寒草甸生物量呈典型的金字塔式垂直分布格局，地上生物量主要集中于0—10cm的冠层，地下生物量也集中分布于0—10cm的土层内。增温和多雨会降低生物量，叶面积和物种丰富度与地上生物量成正相关关系，氮素的增加有助于植被生物量的增长，而放牧率与生物量成显著负相关。     

根据相关条件判断季节的种种方法

1．根据气候特征 地中海气候，热带草原气候，季风气候等季节变化明显的气候类型能指示季节。例如，当罗马、洛杉矶、旧金山、雅典、塔兰托、马赛等炎热干燥时，或珀斯、开普敦、好望角、圣地亚哥多雨时，或南亚盛行西南季风时，尼罗河处于汛期，赞比西河处于枯水期时北半球为夏季，反之为冬季。     

甘肃北山造山带红石山地区正εNd(t)值花岗质岩石的成因及地质意义

在1：5万红岭幅等3幅区域地质调查中，对晚古生代中酸性侵入岩和火山岩的Sm—Nd同位素研究表明，这些不同时代、不同类型的岩石，均表现出高的正εNd（t）值和较低的TDM值，而且变化范围很小，揭示该区花岗质岩石的源岩同位素成分均一，且主要来源于地幔。正εNd（t）值花岗质岩石的存在，可能对研究大陆地壳生长具有重要意义。