中文摘要：

对江苏省多个县（市）分布有浮萍的工业区、生活区、农田水体进行调查与采样，观测各地浮萍种类及其生长水体的富营养化状况，探讨水体pH值，铵态氮、硝态氮、总氮、总磷含量与浮萍分布的关系。调查结果表明，浮萍适宜生长在静止的水体中，流动的河流中较为少见；此外，浮萍适宜生长在农田和生活区水体中，工业区附近样本数较少。江苏省夏季浮萍的主要品种为紫萍（Spirodelapolyrrhiza）、青萍（Lemmaminor）、芜萍（Wolffiaarrhiza）和少根紫萍（Spirodelaoligorrhiza），调查期间未发现稀脉浮萍（Lemmaperpusilla）与品藻（Lemmatrisulca）。紫萍和青萍在所调查的每个采样点均有分布，其生长水体的pH值变化范围（4．5～7．5）较大。浮萍生长水环境的氮、磷养分浓度范围很广，铵态氮、硝态氮、总氮、总磷质量浓度范围分别为0～42、0．2—2．0、0．2～45和0．02～13mg·L-1，尚未发现浮萍分布与水体氮、磷含量之间的必然联系。工业区附近水体中常见紫萍与青萍以共生形式存在，偶尔还伴有芜萍。在利用浮萍去除水中氮、磷营养物质时，应优先考虑利用各地当季优势浮萍品种及不同品种浮萍的共生复合系统，保障浮萍的最大生长量以及对水体氮、磷的最大去除率。

英文摘要：

Surveys were conducted of duckweeds-grown water bodies scattered in industrial, residential, and farming areas in a number of cities or counties to investigate species of the duckweeds and water samples collected for analysis of extent of eutrophication of the water bodies, and further clarify relationships of the distribution of duckweeds with pH and contents of ammonium, nitrate, total nitrogen and total phosphorus in the water. Results show that duckweeds tend to flourish in calm water rather than flowing water, and in water bodies in the farming and residential areas rather than in industrial are- as. In summers of Jiangsu Spirodela polyrrhiza, Lemma minor, Wolffia arrhiza and Spirodela oligorrhiza are the most com- mon duckweeds found in water bodies, and no trace of l_emma perpusilla and Lemma trisulca was found during the survey. Spirodela polyrrhiza and Lemma minor were found in all the water bodies surveyed, with water pH varying in the range of 4. 5 -7.5. The results also show that duckweeds grow well in water bodies, high or low in N and P concentrations, ran- ging from 0 to 42, 0. 2 to 2. 0, 0. 2 to 45 and 0. 02 to 13 mg.L-1 for ammonium, nitrate, total nitrogen and total phos- phorus, respectively. No evidence was found showing that any close relationship existed between duckweeds distribution and concentrations of nitrogen and phosphorus in the water. In industrial areas, there are a variety of factories, including chemical plants, clothing factories, pharmaceutical plants, mcchinary accessories factories, etc. , discharging a high vol- ume of waste containing heavy metals and organic matters. In water bodies in or near the industrial areas, symbiosis of Spi- rodela polyrrh~za and Lemma minor and occasiong Wolffia arrhiza, too, is commonly observed. Therefore, in exploiting the effect of duckweeds removing nutrient substances, like N and P from water, priority should be given to native species of duckweeds dominant in the season and the complex symbiotic system of different species of duckweeds so a