三峡水库香溪河库湾夏季藻类水华的时空动态及其影响因素

2008年6—8月,三峡水库香溪河库湾相继暴发蓝藻和绿藻水华.依据香溪河库湾夏季的每周监测,对研究区2次水华分别进行聚类和判别分析,研究了2次水华的时空动态及其影响因素.结果表明:研究区2次水华过程均可划分为无水华组、过渡组和水华组;2次水华的暴发对可溶性硅(DSi)、硝态氮与亚硝态氮(NO3--N+NO2--N)和磷酸盐(PO43--P)3种营养盐的吸收程度不同;蓝藻水华暴发期间的DSi、总氮/总磷(TN/TP)、DSi/TN和DSi/TP值均低于绿藻水华;判别蓝藻水华暴发的参数为叶绿素a(Chla)、

Highly Oxygenated Triterpenoids from the Marine Red Alga Laurencia mariannensis (Rhodomelaceae)

Two new and one known squalenoid-derived triterpenoids. namely, laurenmariannol (1) and (21 alpha)-21-hydroxythyrsiferol (2). and the known thyrsiferol (3) were isolated and identified from the marine red alga Laurencia mariannensis, which was collected off the coast of Hainan and Weizhou Islands of China. The structures of these compounds were established by means of spectroscopic analyses, as well as by comparison with literature data. Compounds I and 2 displayed significant cytotoxic activity against P-388 tumor cells with IC50 values of 0.6 and 6.6 mu g/ml, respectively.