The modem equivalents of the 14 species suggest that a subtropical evergreen broad - leaved forest was growing in the area surrounding mangdan during miocene , under warm and humid subtropical climate . 2 . numerous specimens of fruit and seed of ruppia were , for the first time , found from the zhangcun formation in the age of late pliocene ( 2 . 3 - 3 . 5 millions years old ) in yushe basin , shanxi , north china 山西省榆社盆地张村地区晚上新世( 2 . 3ma - 3 . 5ma )水生植物川蔓藻属( ruppia )果实和种子的大量发现及其与川蔓藻属2个化石种和5个现代种的比较表明，这些果实和种子属于一个新种?榆社川蔓藻只ruppiayushensissp . nov . 。
The experimental results showed that in the condition of this experiment four algaecides all had strong removing rate on algae , and their removing rate increased with dose increasing , and decreased with algae density increasing . according to the removing rate on algae and cost value or so , the sequence of four algaecides from good to bad were potassium permanganate , copper sulfate , hydrogen peroxide and sodium hypochlorite . in the condition of this experiment , the suitable dose of potassium permanganate was 0 . 8mg / l , the algal removing rate was beyond 90 % and the cost of this algaecide was only 0 . 0068 / m3 . the efficiency of algae removal by four algaecides for huanghe river water was studied . the results showed that the majority of huanghe river water was bacillaroiphyta , and the dominant genera was melosira , which reached 78 % ~ 94 % 结果表明，在实验条件下，四种杀藻剂均具有一定的杀藻效果，藻类去除率均随药剂投量的增加而提高；原水藻类数量影响杀藻剂杀藻效果，四种杀藻剂的藻类去除率均随原水藻类数量的增加而降低；通过杀藻效果、经济性以及安全性等方面的综合比较，对于以有毒蓝藻为优势藻属的引滦水，四种杀藻剂的优劣程度从优到劣排序为：高锰酸钾硫酸铜过氧化氢次氯酸钠；在实验条件下，高锰酸钾适宜投加量为0 . 8mg l ，藻类去除率高于90 ，所需的药剂费用仅为0 . 0068元m ~ 3 。
