长江中游浅水湖泊水生植物氮磷含量与水柱营养的关系

STUDY OF MACROPHYTES NITROGEN AND PHOSPHORUS CONTENTS OF THE SHALLOW LAKES IN THE MIDDLE REACHES OF CHANGJIANG RIVER

水生植物组织内氮和磷(N和P)含量受到水体营养状况和植物生长状况影响。对长江中游江汉湖群不同营养水平湖泊中大型水生植物的N和P含量3个季度的研究表明,在不同生活型水生植物中,沉水植物主要分布在中营养到中富营养湖泊中,在富营养湖泊均无分布,浮叶和挺水植物在不同营养类型湖泊的沿岸带均有分布。N和P含量以沉水植物最高,浮叶植物次之,挺水植物最低。水生植物的N和P含量都达到或超过生长所需最低N和P阈值,代表性浮叶植物和沉水植物的N和P含量随着湖泊营养水平提高呈现规律性变化。湖泊5种常见的水生植物N和P含量与水柱中不同种类N和P浓度具有季节性相关:菱(TrapabispinosaRoxb.)春夏季P含量都与TP(总磷)和TDP(总溶解磷)明显相关,春季N含量与NH4—N(氨氮)明显相关;春季黄丝草(PotamogetonmaackianusA.Benn.)的P含量与TP明显相关,夏季与TDP明显相关,春季和夏季黄丝草和穗花狐尾藻(MyriophyllumspicatumL.)的N含量与TN(总氮)和TDN(总溶解氮)显著正相关,秋季成负相关;夏季芦苇(PhragmitescommunisTrin.)P含量与TP和TDP显著相关;春季芦苇和香蒲(TyphaorientalisPresl.)N含量与NH4N和NO2N(亚硝态氮)显著相关。

Content of tissue nitrogen and phosphorus of aquatic plant is affected by trophic statue of the waters and the plant growth condition.Nitrogen and phosphorus contents(N and P) of aquatic plants of eighteen investigated lakes in the middle reaches of Changjiang River were comparative studied. The results showed that, among all life forms of aquatic plants, the submersed mainly distributed in mesotrophic to meso-eutrophic lakes, while the floating-leaved and emergent in lake's littoral zone of different trophic levels. N and P contents were highest in the submersed and lowest in the emergent, intermediate in floating leaved plants. All aquatic plants reached or exceeded their least requirements of N and P content for maximum growth N and P contents of the major submersed and floating-leaved plants changed relative to increased trophic levels of the lakes. N and P content of 5 aquatic plants showed significant correlations with different N and P species in different growth season. Among the plants of different life form, P content of Trapa natans was related significantly to total phosphorus (TP) and total dissolved phosphorus (TDP) in water in the spring and the summer, its N content related to the ammonia (NH_4-N) in the spring. P content of Potamogeton maackianus was related to TP in the spring and to TDP in the summer. N contents of P. maackianus and Myriophyllum spicatum were positive related to total nitrogen (TN) and total dissolved nitrogen (TDN) in the water both in the spring and the summer, and were negative related in autumn. P contents in shoot and root of Phragmites communis were significantly related to TP and TDP of the water in the summer; N contents in the shoot of P. communis and in Typha latiorlia in spring were related to ammonia (NH_4-N) and nitrite (NO_2-N). Sumersed and floating leaved plants are more correlatived with the nutrition level of lakes than emergent plants are, so it is better to choose the formers as the indicative species of the pollution degree of water quality.